This work was supported by the National Natural Science Foundation of China (21606180), and the Natural Science Basic Research Program of Shaanxi (Program No. 2019JM-589).

1. Preparation of the BrSubPc
NOTE: The BrSubPc sample was prepared according to a previously published work36. The reaction is carried out in a double-row tube vacuum line system, and the reaction process is strictly controlled under water-free and oxygen-free conditions.
<ol>
	<li>Pre-treatment of raw materials
	<ol>
		<li>Weigh 2 g of o-dicyanobenzene, dry it in a vacuum oven for 24 h, take it out and then grind it carefully in an agate mortar.</li>
		<li>Put it again in a vacuum oven for 1 week; then, take it out and put it in a desiccator.</li>
		<li>Measure 50 mL of o-dichlorobenzene, add 1 g of anhydrous magnesium sulfate, and stir the mixture at room temperature (RT) for 24 h at medium speed.</li>
	</ol>
	</li>
	<li>Then, filter the solution under reduced pressure (-0.1-0.09 MPa), collect the filtrate, and set it aside.</li>
	<li>Add pretreated o-dicyanobenzene (10 mmol, 1.28 g) into a 100 mL Schlenk bottle, evacuate the system with a double-row tube vacuum line device, and fill the system with nitrogen. Then, inject 50 mL of pretreated o-dichlorobenzene under magnetic stirring at 1,000 rpm for 1 h to disperse o-dicyanobenzene uniformly.</li>
	<li>Put the Schlenk bottle into an ice water bath, then add 1.3 mL of Boron tribromide (BBr3) under magnetic stirring at 1,000 rpm for 120 min, and observe the color of the reaction system change to dark brown.</li>
	<li>Then, quickly switch to an oil bath, raise the temperature to 120 &#176;C reflux for 10 h, and observe the color of the reaction system change from dark brown to bright purple.</li>
	<li>Stop heating and cool to RT. Filter the solution under reduced pressure (-0.1-0.09 MPa) and collect the filter cake, with the purple solid on the cake being the crude product.</li>
	<li>Put the obtained BrSubPc crude product into a vacuum oven for 20 h. Remove and finely grind the product. Then, extract with 200 mL of methanol solution in a Soxhlet extractor until the solution becomes colorless.</li>
</ol>
2. Preparation of the Rhombic dodecahedral Ag3PO4
NOTE: Rhombic dodecahedral Ag3PO4 was prepared according to the previously reported literature35.
<ol>
	<li>Preparation of the reaction solution
	<ol>
		<li>For NH4NO3 solution (0.05 M) named Solution 1, dissolve 6 g of ammonium nitrate (NH4NO3, 99%) in 200 mL of deionized water, and treat with ultrasonic waves at 40 Khz frequency, 300 W power for 5 min in one cycle to dissolve it completely. Then, put it into a 500 mL volumetric flask to fix the volume.</li>
		<li>For NaOH solution (0.2 M) named Solution 2, dissolve 4 g of sodium hydroxide (NaOH, 99%) in 200 mL deionized water in a glass beaker, and sonicate for 5 min at 40 Khz frequency, 300 W power in one cycle to dissolve it fully. Then, put it into a 500 mL volumetric flask to fix the volume.</li>
		<li>For AgNO3 solution (0.05 M) named Solution 3, dissolve 4.25 g of silver nitrate (AgNO3, 99.8%) in 200 mL deionized water in a glass beaker, and sonicate for 5 min at 40 Khz frequency, 300 W power in one cycle to dissolve it fully. Then, put it into a 500 mL volumetric flask to fix the volume.</li>
		<li>For the K2HPO4 solution (0.1 M) named Solution 4, dissolve 11.41 g of potassium hydrogen phosphate (K2HPO4, 99.5%) in 400 mL deionized water in a glass beaker, and sonicate for 5 min to dissolve it fully. Then, put it into a 500 mL volumetric flask to fix the volume.</li>
	</ol>
	</li>
	<li>Add 2526 mL of deionized water to a beaker, and then add 180 mL of NH4NO3 solution (0.4 M), 54 mL of NaOH solution (0.2 M), and 120 mL of AgNO3 solution (0.05 M) sequentially to the beaker.</li>
	<li>Stir the solution vigorously for 10 min to prepare the [Ag(NH3)2]+ complex. Finally, add 120 mL of K2HPO4 solution (0.1 M) to the complex and stir for 5 min. After the color of the solution changes from colorless to light yellow, the precipitate obtained is Ag3PO4 rhombic dodecahedral.</li>
	<li>Separate the resulting precipitate by centrifugation at 7155.5 x g for 10 min at RT and subsequently centrifuge it three times with 50 mL of deionized water in the same conditions. Store the rhombic decahedral Ag3PO4 at RT in a dry environment away from light.</li>
</ol>
3. Preparation of BrSubPc/Ag 3PO4
NOTE: Four different composite ratios of BrSubPc to Ag3PO4 were prepared according to the mass ratios of 1:25, 1:50, 1:75, and 1:100.
<ol>
	<li>Dissolve 5.77 mg of BrSubPc in 50 mL of ethanol in a glass beaker. Dissolve the BrSubPc completely by sonication at 40 Khz frequency, 300 W power in one cycle for 30 min at RT.</li>
	<li>Then, add 144.25 mg of Ag3PO4 to the above solution and sonicate at 40 kHz frequency, 300 W power in one cycle for 30 min at RT.</li>
	<li>Stir the above solution in an 80 &#176;C water bath to allow complete evaporation of the ethanol.</li>
	<li>Dry the resulting brownish-yellow powder overnight in an oven at 60 &#176;C. The prepared sample is named as BrSubPc/Ag3PO4 (1:25).</li>
	<li>For the other composite ratio samples (1:50, 1:75, and 1:100), follow the same preparation procedure (steps 3.1-3.4) as BrSubPc/Ag3PO4 (1:25) but change the amount of BrSubPc to 2.94 mg, 1.97 mg, and 1.49 mg, and the corresponding amount of Ag3PO4 to 147.0 mg, 147.75 mg, and 149.0 mg, respectively.</li>
</ol>
4. Characterization of the samples
<ol>
	<li>Perform X-ray diffraction analysis of powdered materials using a monochromatic Cu-K&#945; light source, &#955; = 0.15418 nm, operating at 30 kV and 15 mA.</li>
	<li>Use Fourier transform infrared spectroscopy (FT-IR) to characterize the structural features of the as-prepared materials; the measurement wavelength range is 500-4000 cm-1.</li>
	<li>Measure the absorption properties of the as-prepared materials by solid ultraviolet-visible (UV-vis) absorption spectroscopy in the range of 200-800 nm.</li>
	<li>Determine the particle size, microstructure, and morphology of the prepared samples by scanning electron microscopy at 5.00 KV accelerating voltage, InLens detector, magnification 500-13000, working distance 7.4-7.7 mm.</li>
	<li>Take 5 mL of the reaction solution after 5 cycles, and fix the volume to 10 mL using concentrated HNO3. Digest the reaction solution with an inductively coupled plasma-optical emission spectrometer (ICP-OES) at a pump rate of 100 r/min, a nebulizer flow of 28.0 psi, auxiliary gas of 0.5 mL/min and a sample flush time of 20 s.</li>
</ol>
5. Photocatalytic activity test
NOTE: The light source is a 300 W xenon lamp, and a 400 nm filter is used to remove ultraviolet light from the light source. The xenon lamp was mounted 15&#8239;cm above the solution, and the light intensity was determined to be 350&#8239;mW/cm2.
<ol>
	<li>For the test solution, 10 mg of tetracycline (TC) was dissolved in 500 mL of distilled water to obtain a 20 ppm solution.</li>
	<li>Then, transfer 50 mL of the test TC solution to a glass photocatalytic reactor. Stir the solution thoroughly with a magnetic stirrer at 1000 rpm and maintain the temperature at 25 &#176;C. Then, turn the air pump switch on and add the air to the solution at a rate of 100 mL/min to maintain air saturation.</li>
	<li>Add 50 mg of the prepared photocatalyst to the test solution to reach a concentration of 1 g/L.</li>
	<li>Take the first sample (3 mL) immediately using a glass syringe. After stirring for 30 min in the dark, take the second sample and turn on the light source.</li>
	<li>After irradiation for 5 min, 10 min, 15 min, 20 min, and 30 min, take liquid samples (3 mL). Filter all the extracted samples through a 0.22 &#181;m nylon membrane to remove solid particles before analysis. Store the filtered samples away from light in 5 mL centrifuge tubes until analysis.</li>
	<li>Measure the concentration of TC with a UV-Vis spectrophotometer at 356 nm. Evaluate the photocatalytic effect by the degradation rate; the specific calculation formula of the degradation rate is as follows (Eq. (1)). 
	<img alt="Equation 1" src="/files/ftp_upload/64478/64478eq01.jpg" style="margin: auto;" />&#160; &#160;(1) 
	Where, A0 is the absorbance of the sample before illumination, A is the absorbance of the sample at illumination time of t min.</li>
	<li>Use the same experimental procedures for different catalyst dosages, with starting catalyst amounts as 30 mg, 40 mg, 50 mg, 60 mg, and 70 mg.</li>
	<li>For experiments with different pHs, adjust the pH of the tetracycline solution (50 mL, 20 mg/L) between 2.0 and 9.0 with 0.01 mol/L HCl and NaOH solution. Use BrSubPc/Ag3PO4 as the catalyst with a catalyst dosage of 50 mg. For other photocatalytic experimental procedures, follow the previously described steps 5.2-5.6.</li>
	<li>Investigate the effect of reaction temperature on the photodegradation of tetracycline by using BrSubPc/Ag3PO4 as the catalyst with a catalyst dosage of 50 mg and solution pH = 6; the temperature range is 10-50 &#176;C. Other photocatalytic experimental procedures are the same as the previously described steps 5.2-5.6.</li>
	<li>Investigate the effects of different anions on the photocatalytic performance of the catalysts by adding 5 mmol/L Na2SO4, 5 mmol/L Na2CO3, 5 mmol/L NaCl, and 5 mmol/L NaNO3 to 50 mL of tetracycline solution, respectively. Use BrSubPc/Ag3PO4 as the catalyst with a catalyst dosage of 50 mg and solution pH = 7. Other photocatalytic experimental procedures are the same as the previously described steps 5.2-5.6.</li>
	<li>After each cycle of photocatalytic degradation reaction, centrifuge the reacted solution at 7155.5 x g for 10 min at RT, and then centrifuge it three times with 10 mL of deionized water in the same conditions (3 x 10 mL). Dry the solid at 120 &#176;C for 1 h. Perform five consecutive photodegradation experiments using photocatalysts that were recovered after each step with no change in the overall concentration of the catalyst to evaluate the stability of the BrSubPc/Ag3PO4 photocatalyst.</li>
</ol>

The authors have nothing to disclose.

In this paper, we present a complete methodology for evaluating the catalytic performance of photocatalytic materials, including the preparation of catalysts, the investigation of factors affecting photocatalysis, and the performance of catalyst recycling. This evaluation method is universal and applicable to all photocatalytic material performance evaluations.
In terms of material preparation methods, many schemes have been reported for the preparation of rhombic dodecahedral Ag3PO4 using different precursors21,22. The method we have used is relatively homogeneous in terms of the shape of the Ag3PO4 synthesized, the synthesis process is simple, large quantities can be synthesized, and there are fewer factors affecting the experimental process. It should be noted that ammonium nitrate, a raw material for the synthesis of Ag3PO4, is an oxidizing agent and is subject to explosive decomposition by violent impact or heat, so it should be stored and used to avoid violent impact. In the synthesis of the composites, BrSubPc was firstly dissolved in sufficient amount of ethanol solution to destroy the weak forces between BrSubPc molecules (hydrogen bonding, &#960;&#8722;&#960; interaction), then Ag3PO4 was added in an appropriate amount, and the ethanol was evaporated by heating, during which the BrSubPc molecules reassemble themselves on the Ag3PO4 surface through intermolecular hydrogen bonding and &#960;&#8722;&#960; interaction.
The effect of different catalyst amounts, solution pH, anions in solution, and reaction temperature on the photocatalytic performance of the prepared materials was investigated. The airflow rate, the intensity of the light source, and the distance of the light source from the reactor should be controlled when doing photocatalytic reactions with different influencing factors. When filtering samples using 0.22 &#181;m nylon membrane, it should be noted that not all degradation contaminants are suitable for use with 0.22 &#181;m nylon membrane as some contaminants are inherently blocked by 0.22 &#181;m nylon membrane, in which case centrifugation should be used to separate the catalyst from the reaction solution. Therefore, a 0.22 &#181;m nylon membrane should be used to filter a simple solution of contaminants without a catalyst to exclude the possibility that the contaminants themselves may be blocked by the 0.22 &#181;m nylon membrane.
A catalyst can only be considered to be a promising photocatalyst if it shows good catalytic performance under this evaluation system and not if only a single influencing factor is studied without taking into account environmental factors. In addition, to promote the healthy development of the field of photocatalytic environmental purification, we believe that the same evaluation criteria should be set for the same pollutant, for example, a uniform TC concentration of 20 mg/L, a catalyst dosage of 1 g/L, a light intensity of 350 mW/cm2, an airflow rate of 100 mL/min and a temperature of 30 &#176;C should be used for TC degradation, so that the best catalyst for degrading the same pollutant can be selected by comparing different literature reports.
The photocatalytic performance of the photocatalyst is more comprehensive than that reported in some papers39,40,41, especially in the laboratory photocatalytic experiments to ensure a stable oxygen content in the water and to take into account the thermal effect. The limitation of this scheme is that it does not consider the effect of reactor optical thickness and catalyst optical properties on photocatalytic performance, both of which are important when performing scale-up labs42,43,44. This scheme provides a reference for evaluating the removal of antibiotic-like molecules from water by photocatalysts in the laboratory and compensates for the lack of uniform criteria for evaluating the photocatalytic water purification ability of photocatalysts in the field. This research protocol can be extended to other photocatalytic fields, such as photocatalytic hydrogen production and photocatalytic carbon dioxide reduction45,46. It is recommended that each field should have a set of strict research protocol criteria for evaluating the catalytic performance of catalysts, which will help to select the best photocatalysts for early experimental industrial applications.

Tetracyclines (TCs) are common antibiotics that provide effective protection against bacterial infections and are widely used in animal husbandry, aquaculture, and disease prevention1,2. They are widely distributed in water due to their overuse and improper application in the past decades, as well as the discharge of industrial wastewater3. This has caused severe environmental pollution and serious risks to human health; for example, the excessive presence of TCs in the aqueous environment can negatively affect microbial community distribution and bacterial resistance, leading to ecological imbalances, mainly due to the highly hydrophilic and bioaccumulative nature of antibiotics, as well as a certain level of bioactivity and stability4,5,6. Due to the hyper-stability of TC in the environment, it is difficult to break down naturally; therefore, many methods have been developed, including biological, physicochemical, and chemical treatments7,8,9. Biological treatments are highly efficient and low-cost10,11. However, because they are toxic to microorganisms, they do not effectively degrade and mineralize antibiotic molecules in water12. Although physicochemical methods can remove antibiotics from wastewater directly and quickly, this method only converts the antibiotic molecules from the liquid phase to the solid phase, does not completely degrade them, and is too costly13.
In contrast to conventional methods, semiconductor photocatalysis has been widely used for the degradation of pollutants in the past decades due to its efficient catalytic degradation properties14. For example, the noble metal-free magnetic FexMny catalyst of Li et al. achieved efficient photocatalytic oxidation of a variety of antibiotic molecules in water without the use of any oxidant15. Yan et al. reported the in situ synthesis of lily-like NiCo2O4 nanosheets on waste biomass-derived carbon to achieve efficient photocatalytic removal of phenolic pollutants from water16. The technology relies on a semiconductor catalyst excited by light to generate photogenerated electrons (e-) and holes (h+)17. The photogenerated e- and h+ will be converted into superoxide anion radicals (O2-) or hydroxyl radicals (OH-) by reacting with absorbed O2 and H2O, and these oxidatively active species oxidize and decompose organic pollutant molecules in water into CO2 and H2O and other smaller organic molecules18,19,20. However, there is no unified field standard for photocatalyst performance evaluation. The evaluation of a material&#39;s photocatalytic performance should be investigated in terms of the catalyst preparation process, environmental conditions for optimal catalytic performance, catalyst recycling performance, etc. Ag3PO4, with its prominent photocatalytic ability, has triggered substantial concern in environmental remediation. This new photocatalyst achieves quantum efficiencies of up to 90 % at wavelengths greater than 420 nm, which is significantly higher than previously reported values21. However, the severe photo corrosion and unsatisfactory electron-hole separation rate of Ag3PO4 limit its wide application22. Therefore, various attempts have been made to overcome these drawbacks, such as shape optimization23, ion doping24, and heterostructure building25,26,27. In this paper, Ag3PO4 was modified using morphology control as well as heterojunction engineering. First, rhombic dodecahedral Ag3PO4 crystals with high surface energy were prepared by solvent phase synthesis at room temperature under ambient pressure. Then, organic supramolecular BrSubphthalocyanine (BrSubPc), which can act as both electron acceptor and electron donor, was self-assembled on the silver phosphate surface by the solvothermal method28,29,30,31,32,33,34,35. The photocatalytic performance of the prepared materials was evaluated by investigating the effect of different environmental factors on the photocatalytic performance of the prepared samples to degrade trace amounts of tetracycline in water. This paper provides a reference for the systematic evaluation of the photocatalytic performance of the materials, which is of significance for the future development of photocatalytic materials for practical applications in environmental remediation.

<table><tbody><tr><td>300 W xenon lamp</td><td>CeauLight</td><td>CEL-HXF300</td><td></td></tr><tr><td>AgNO&lt;sub&gt;3&lt;/sub&gt;</td><td>Aladdin Reagent (Shanghai) Co., Ltd.</td><td>7783-99-5</td><td></td></tr><tr><td>Air Pump</td><td>Samson Group Co.</td><td>ACO-001</td><td></td></tr><tr><td>BBr&lt;sub&gt;3&lt;/sub&gt;</td><td>Bailingwei Technology Co., Ltd.</td><td>10294-33-4</td><td></td></tr><tr><td>Constant temperature circulating water bath</td><td>Beijing Changliu Scientific Instruments Co.</td><td>HX-105</td><td></td></tr><tr><td>Dichloromethane</td><td>Tianjin Kemiou Chemical Reagent Co., Ltd.</td><td>75-09-2</td><td></td></tr><tr><td>Ethanol</td><td>Tianjin Fuyu Fine Chemical Co., Ltd.</td><td>64-17-5</td><td></td></tr><tr><td>Fourier-transform infrared</td><td>Bruker</td><td>Vector002</td><td></td></tr><tr><td>Hexane</td><td>Tianjin Kemiou Chemical Reagent Co., Ltd.</td><td>110-54-3</td><td></td></tr><tr><td>HNO&lt;sub&gt;3&lt;/sub&gt;</td><td>Aladdin Reagent (Shanghai) Co., Ltd.</td><td>7697-37-2</td><td></td></tr><tr><td>ICP-OES</td><td>Aglient</td><td>5110</td><td></td></tr><tr><td>K&lt;sub&gt;2&lt;/sub&gt;HPO&lt;sub&gt;4&lt;/sub&gt;</td><td>Aladdin Reagent (Shanghai) Co., Ltd.</td><td>16788-57-1</td><td></td></tr><tr><td>Magnesium Sulfate</td><td>Tianjin Kemiou Chemical Reagent Co., Ltd.</td><td>10034-99-8</td><td></td></tr><tr><td>Methanol</td><td>Tianjin Kemiou Chemical Reagent Co., Ltd.</td><td>67-56-1</td><td></td></tr><tr><td>NaOH</td><td>Aladdin Reagent (Shanghai) Co., Ltd.</td><td>1310-73-2</td><td></td></tr><tr><td>NH&lt;sub&gt;4&lt;/sub&gt;NO&lt;sub&gt;3&lt;/sub&gt;</td><td>Sinopharm Group Chemical Reagent Co., Ltd.</td><td>6484-52-2</td><td></td></tr><tr><td>o-dichlorobenzene</td><td>Tianjin Fuyu Fine Chemical Co., Ltd.</td><td>95-50-1</td><td></td></tr><tr><td>o-dicyanobenzene</td><td>Sinopharm Group Chemical Reagent Co., Ltd.</td><td>91-15-6</td><td></td></tr><tr><td>Scanning electron microscopy</td><td>JEOL</td><td>JSM-6390</td><td></td></tr><tr><td>Trichloromethane</td><td>Tianjin Kemiou Chemical Reagent Co., Ltd.</td><td>67-66-3</td><td></td></tr><tr><td>Ultraviolet-visible Spectrophotometer</td><td>Shimadzu</td><td>UV-3600</td><td></td></tr><tr><td>X-ray diffractometer</td><td>Rigaku</td><td>D/max-IIIA</td><td></td></tr></tbody></table>

a complete method for evaluating the performance of photocatalysts for the degradation of antibiotics in environmental remediation

Various antibiotics such as tetracycline, aureomycin, amoxicillin, and levofloxacin are found in large quantities in groundwater and soil systems, potentially leading to the development of resistant and multi-drug resistant bacteria, posing a threat to humans, animals, and environmental systems. Photocatalytic technology has attracted keen interest due to its rapid and stable treatment and direct use of solar energy. However, most studies evaluating the performance of semiconductor catalysts for the photocatalytic degradation of organic pollutants in water are currently incomplete. In this paper, a complete experimental protocol is designed to comprehensively evaluate the photocatalytic performance of semiconductor catalysts. Herein, rhombic dodecahedral silver phosphate was prepared by a simple solvent phase synthesis method at room temperature and atmospheric pressure. BrSubphthalocyanine/Ag3PO4 heterojunction materials were prepared by the solvothermal method. The catalytic performance of as-prepared materials for the degradation of tetracycline was evaluated by studying different influencing factors such as catalyst dosage, temperature, pH, and anions at atmospheric pressure using a 300 W xenon lamp as a simulated solar light source and a light intensity of 350 mW/cm2. Compared with the first cycle, the constructed BrSubphthalocyanine/Ag3PO4 maintained 82.0% of the original photocatalytic activity after five photocatalytic cycles, while the pristine Ag3PO4 maintained only 28.6%. The stability of silver phosphate samples was further tested by a five-cycle experiment. This paper provides a complete process for evaluating the catalytic performance of semiconductor catalysts in the laboratory for the development of semiconductor catalysts with potential for practical applications.

The rhombic dodecahedron Ag3PO4 was successfully synthesized using this solvent phase synthesis method. This is confirmed by the SEM images shown in Figure 1A,B. According to the SEM analysis, the average diameter of the rhombic dodecahedral structure was found to be between 2-3 &#181;m. The pristine BrSubPc microcrystals show a large irregular flake structure (Figure 1C). In the composite sample, the titanium dioxide still kept the original nanosphere structure, but no phthalocyanine sheet structure was found, which means that the phthalocyanine molecules were uniformly self-assembled on the titanium dioxide surface (Figure 1D). As shown in Figure 2A, all the samples show a characteristic peak located at 20.9&#176;, 29.7&#176;, 33.3&#176;, 36.6&#176;, 42.5&#176;, 47.8&#176;, 52.7&#176;, 55.0&#176;, 57.3&#176;, 61.6&#176;, 65.8&#176;, 69.9&#176;, 71.9&#176;, and 73.8&#176; which were attributed to the (110), (200), (210), (211), (220), (310), (222), (320), (321), (400), (330), (420), (421) and (332) facets of the body-centered cubic structure of Ag3PO4 (JCPDS No. 06-0505)21. On the other hand, BrSubPc/Ag3PO4 samples did not show additional characteristic peaks of BrSubPc, mainly because of the amount of BrSubPc loaded on the surface of Ag3PO4 was low and the intensity of the main diffraction peak of Ag3PO4 decreased as the amount of BrSubPc increased. The FT-IR spectra of the as-prepared samples are analyzed as shown in Figure 2B. For BrSubPc, the more abundant characteristic peaks in the FT-IR spectrum are peaks at 743 cm-1, 868 cm-1, 943 cm-1, and 1452 cm-1; this feature is the stretching and bending vibration of the C-C and C-N bonds of the benzene ring backbone. The weak peak at 624 cm-1 is the characteristic peak of the stretching of the B-Br bond. The symmetric and asymmetric stretching vibrations of P-O-P caused the same FT-IR peaks at 546 cm-1 and 931 cm-1 for pristine Ag3PO4 and BrSubPc/Ag3PO4, respectively. The pristine Ag3PO4 can absorb light at wavelengths less than 530 nm, and BrSubPc has two characteristic peaks at 310 nm and 570 nm, respectively (Figure 2C). Compared with pure Ag3PO4, the BrSubPc/Ag3PO4 composite sample shows significantly increased absorption in the visible region, confirming that the Ag3PO4 particles are successfully covered by BrSubPc microcrystals. This can prove that the BrSubPc/Ag3PO4 composite is a very promising visible-light-induced photocatalyst.
The photocatalytic activity of the as-prepared materials was assessed following the degradation of the antibiotic TC in pure water under simulated visible light irradiation (&#955; &#62; 400 nm). As shown in Figure 3A, the photocatalytic performance of pristine Ag3PO4 showed only 72.86% degradation of TC after 0.5 h of visible light irradiation. It can be observed that all the composite photocatalysts showed enhanced degradation of TC when BrSubPc supramolecular nanocrystals were loaded on the surface of Ag3PO4. In particular, BrSubPc/Ag3PO4 (1:50) achieved 94.54% degradation of TC after 0.5 h of visible light illumination, respectively. A pseudo-first-order reaction model (l&#8722;ln (C/C0) = kt)28, where k is the apparent rate constant, was used to fit the kinetics of photodegradation of TC by different samples. As shown in Figure 3B, the apparent rate constant of TC degradation by BrSubPc/Ag3PO4 (1:50) composites was 1.69 times higher than that of the pristine Ag3PO4. The above results indicate that the photocatalytic performance of Ag3PO4 is significantly improved when Ag3PO4 is combined with BrSubPc supramolecular nanocrystals.
The photostability and reusability of photocatalysts are important factors affecting their practical applications, and recycling degradation experiments were conducted on the as-prepared pristine Ag3PO4 and BrSubPc/Ag3PO4 (1:50) composites. Figure 3C shows that after five cycles of the prepared catalysts, the composite still showed a high TC removal rate of 77.5%. However, the TC removal by pristine Ag3PO4 decreased from 72.86% to 20.84%. In addition, XRD analysis of the cycled composite BrSubPc/Ag3PO4 (1:50) samples showed that the XRD peaks of the cycled samples did not change compared with the XRD of the original samples (Figure 4), which proved the good stability of the composite samples in the photocatalytic reaction. The ICP-OES test results of the reaction solution after five cycles showed that the concentration of elemental silver in the solution after the reaction of pristine Ag3PO4 was 1.3 mg/L, while the concentration of elemental silver in the solution after the reaction of the composite sample of BrSubPc/Ag3PO4 (1:50) was 0.1 mg/L (Table 1). This indicates that the composite sample photocatalytic reaction has better stability compared to that of pristine Ag3PO4.
In the photocatalytic process, the amount of photocatalyst dosage also has an important influence on the photocatalytic effect, too little dosage may lead to lower light utilization efficiency and poor photocatalytic effect, and too much photocatalyst dosage may lead to higher cost and uneconomical. Too little amount of photocatalyst may lead to lower light utilization efficiency and poor photocatalytic effect, while too much amount of photocatalyst may lead to higher cost and uneconomical treatment of wastewater. Therefore, it is important to determine the optimal photocatalyst dosage. As can be seen from Figure 5A, after 30 min of dark reaction, the adsorption and removal of tetracycline increased as the concentration of the photocatalyst in the reaction solution increased (the dosage increased) because the concentration of tetracycline as the adsorbent in the solution remained the same, while the concentration of the photocatalyst as the adsorbent increased, which means that the active point on the surface of the adsorbent in the solution also increased, and the probability of collision adsorption with the adsorbent increased. This means that the probability of collisional adsorption with the adsorbate increases, resulting in a decrease in the concentration of adsorbate in the solution. The degradation rate of TC by photocatalysts at 0.6 g/L, 0.8 g/L, 1 g/L, 1.2 g/L, and 1.4 g/L was 71.6%, 75.0%, 94.5%, 95.7%, and 95.7% after 30 min of light reaction, respectively. When the concentration of the catalyst exceeded 1.0 g/L, the degradation rate of TC could reach more than 90% in 30 min of photoreaction. From the above analysis, it can be seen that when the concentration of photocatalyst is 1.4 g/L, the best removal effect of tetracycline is achieved, and the photocatalytic effect was not greatly improved compared with the catalyst concentration of 1.0 g/L, while the catalyst dosage was 40% higher. The analysis of the degradation kinetic data in Figure 5B also shows that 1.4 g/L and 1.2 g/L are not significantly different compared to 1.0 g/L. From the economic point of view, the optimal dosage of composite material is 1.0 g/L.
As can be seen in Figure 5C, the effect of pH on the photocatalytic degradation of the composite material for the removal of TC is relatively large. The TC aqueous solution pH was detected to be 6, showing the best degradation efficiency. The photocatalytic performance of the composites was slightly reduced in acidic solutions, while the TC degradation efficiency was more attenuated in neutral and alkaline solutions. The maximum kinetic data for degradation TC can also be seen in Figure 5D at solution pH = 6. In alkaline solutions with high pH, tetracycline will be present in the solution in the form of TC-, which will have electrostatic repulsion with the catalyst, resulting in poor degradation of tetracycline. In acidic solutions with low pH, tetracycline is mainly present in the solution as TC+, and H+ will compete with TC+ in the solution to be absorbed by the photocatalyst, inhibiting the TC+ contact with the photocatalyst, thus reducing the photocatalytic activity in the system.
In reality, antibiotic wastewater often also contains some anions (Cl-, SO42-, NO3-, CO32-, etc.), and these common anions may also affect the photocatalytic process. As can be seen in Figure 5E, the addition of SO42- inhibited the adsorption of TC molecules on the catalyst surface during the dark reaction phase. This may be since SO42-, as a negatively charged anion, competes with the tetracycline molecules for the active site on the photocatalyst surface, resulting in a reduction in the number of tetracycline molecules that can undergo catalytic oxidation or the formation of a highly polar environment close to the photocatalyst surface, preventing the expansion of tetracycline to the active site of the photocatalyst37. When the light reaction was carried out for 30 min, the TC degradation rate in the system without the anion was 94.5%, while in the system with the Cl-, SO42-, NO3-, and CO32- anion, the TC degradation rate was 79.2%, 77.3%, 85%, and 80.3%, respectively. TC degradation kinetic data also reflects the inhibition of TC degradation by the addition of all anions (Figure 5F). The addition of all anions had an inhibitory effect on the photocatalytic degradation of TC, but the TC degradation rate was not overly affected.
The results of the effect of temperature on the photocatalytic degradation of TC are shown in Figure 5G. The degradation rates were 35.3%, 70.6%, 94.5%, 96.5%, and 98.0% for 30 min of photoreaction at 10&#176;C, 20&#176;C, 30&#176;C, 40&#176;C, and 50 &#176;C, respectively. The degradation rate of tetracycline gradually increased with the increase in temperature. The degradation kinetic data for TC from Figure 5H also shows that temperature has a large effect on the degradation efficiency. Tetracycline molecules migrate more quickly as a result of the rising temperature of the solution, making them easier to adsorb when in contact with the catalyst surface. Additionally, at higher temperatures, photogenerated electron-hole pairs more actively, allowing electrons to bind to adsorbed oxygen more quickly and holes to produce hydroxyl radicals with -OH in water more quickly, which speeds up the destruction of tetracycline38.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/64478/64478fig01.jpg" /> 
Figure 1: SEM images. (A,B) Ag3PO4. The left side shows a low-resolution image, and the right side provides a magnified image. (C) BrSubPc and (D) BrSubPc/Ag3PO4. All samples were measured in the powder state. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/64478/64478fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 2" class="xfigimg" src="/files/ftp_upload/64478/64478fig02.jpg" /> 
Figure 2: XRD, FT-IR, and UV-Vis spectra of the samples. (A) XRD patterns. For XRD analysis, the scanning range was 10&#176;-80&#176;, and the scanning speed was 8&#176;/min. The numbers placed vertically at the bottom indicate the corresponding crystal plane. (B)&#160;FT-IR spectrum. All samples were tested in the dried powder state. (C) UV-vis spectra of the samples. Solid powders were used for the measurement at a range of 200-800 nm. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/64478/64478fig02large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 3" class="xfigimg" src="/files/ftp_upload/64478/64478fig03.jpg" /> 
Figure 3: TC photocatalytic degradation. (A) TC photocatalytic degradation, the vertical coordinate C0 indicates the initial absorbance of TC (0.664) measured using a UV-vis spectrophotometer, and C indicates the absorbance of TC at each sampling point. (B) The apparent rate constants k for TC photodegradation of Ag3PO4 and BrSubPc/Ag3PO4, calculated from the pseudo-first-order reaction model (l-ln(C/C0) = kt). (C) Cycle experiment of BrSubPc/Ag3PO4 (1:50) for TC photocatalytic degradation reaction, the latter reactions are all based on the samples collected after the previous step. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/64478/64478fig03large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 4" class="xfigimg" src="/files/ftp_upload/64478/64478fig04.jpg" /> 
Figure 4: XRD patterns of BrSubPc/Ag3PO4. XRD patterns of BrSubPc/Ag3PO4 (1:50) before and after the photocatalytic reaction at a scanning range of 10&#176;-80&#176; and a scanning speed of 8&#176;/min. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/64478/64478fig04large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<img alt="Figure 5" class="xfigimg" src="/files/ftp_upload/64478/64478fig05.jpg" /> 
Figure 5: Exploring TC photocatalytic degradation under the influence of different factors. (A) different catalyst dosages, (C) different pH, (E) different anions and (G) different temperatures. The apparent rate constants k for TC photodegradation using (B) different catalyst dosages, (D) different pH, (F) different anions, and (H) different temperatures. <a href="https://www-jove-com.remotexs.ntu.edu.sg/files/ftp_upload/64478/64478fig05large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Sample</td>
			<td>Test elements</td>
			<td>Sample elemental content (mg/L)</td>
		</tr>
		<tr>
			<td>Ag3PO4</td>
			<td>Ag</td>
			<td>1.3</td>
		</tr>
		<tr>
			<td>BrSubPc:Ag3PO4 (1:50)</td>
			<td>Ag</td>
			<td>0.1</td>
		</tr>
	</tbody>
</table>
Table 1: ICP-OES data. Ag elemental concentration data in the reaction solution after five cycles of testing using ICP-OES.

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A Complete Method for Evaluating the Performance of Photocatalysts for the Degradation of Antibiotics in Environmental Remediation

Presented here is a protocol to explore a universal set of experimental procedures for comprehensive laboratory evaluation of photocatalysts in the field of environmental purification, using the example of photocatalytic removal of antibiotic organic pollutant molecules from water by phthalocyanine sensitized silver phosphate composites.

Various antibiotics such as tetracycline, aureomycin, amoxicillin, and levofloxacin are found in large quantities in groundwater and soil systems, ...

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Nanyang Technological University

Research

JoVE Journal

Environment

2.1K Views.  Northwest University. Dit artikel biedt een compleet proces voor het evalueren van de katalytische prestaties van halfgeleiderkatalysatoren in het laboratorium om halfgeleiderkatalysatoren te ontwikkelen met potentieel voor praktische toepassingen. Het voordeel van deze techniek is dat de fotokatalytische prestaties van halfgeleiderkatalysatoren in het laboratorium uitgebreider kunnen worden geëvalueerd. Bing Wang, een promovendus van het laboratorium van Zhuo Li.En XuXia Zhang, LeCheng Li, MengTing Ji, Zheng Zhe...

Video: A Complete Method for Evaluating the Performance of Photocatalysts for the Degradation of Antibiotics in Environmental Remediation

Analyzing the Photo-oxidation of 2-propanol at Indoor Air Level Concentrations Using Field Asymmetric Ion Mobility Spectrometry

We demonstrate a versatile protocol to be used for determining the effectiveness of photocatalysts in degrading indoor air concentration (ppb) volatile organic carbons (VOCs), illustrating this with a titanium dioxide based catalyst, and the VOC 2-propanol. The protocol takes advantage of field asymmetric ion mobility spectroscopy (FAIMS), an analysis tool that is capable of continuously identifying and monitoring the concentration of VOCs such as 2-propanol and acetone at the ppb level. The continuous nature of FAIMS allows detailed kinetic analysis, and long-term reactions, offering a significant advantage over gas chromatography, a batch process traditionally used in air purification characterization. The use of FAIMS in photocatalytic air purification has only recently been used for the first time, and with the protocol illustrated here, the flexibility in allowing alternative VOCs and photocatalysts to be tested using comparable protocols offers a unique system to elucidate photocatalytic air purification reactions at low concentrations.

A protocol for determining the effectiveness of photocatalysts in degrading indoor air concentration (ppb) model volatile organic carbons such as 2-propanol is described.

We demonstrate a versatile protocol to be used for determining the effectiveness of photocatalysts in degrading indoor air concentration (ppb) volatile ...

Chemistry

Identification of Pharmaceuticals in The Aquatic Environment Using HPLC-ESI-Q-TOF-MS and Elimination of Erythromycin Through Photo-Induced Degradation

Monitoring pharmaceuticals throughout the water cycle is becoming increasingly important for the aquatic environment and eventually for human health. Targeted and non-targeted analysis are today's means of choice. Although targeted analysis usually conducted with the help of a triple quadrupole mass spectrometer may be more sensitive, only compounds previously selected can be identified. The most powerful non-targeted analysis is performed through time of flight mass spectrometers (TOF-MS) extended by a quadrupole mass analyzer (Q), as used in this study. Preceded by solid phase extraction and high-performance liquid chromatography (HPLC), the non-targeted approach allows to detect all ionizable substances with high sensitivity and selectivity. Taking full advantage of the Q-TOF-MS instrument, tandem mass spectrometry (MS/MS) experiments accelerate and facilitate the identification while a targeted MS method enhances the sensitivity but relies on reference standards for identification purposes. The identification of four pharmaceuticals from Rhine river water is demonstrated. The Rhine river originates in Tomasee, Graub&#252;nden, Switzerland and flows into the North Sea, near Southern Bight, The Netherlands. Its length amounts to 1232.7 km. Since it is of prime interest to effectively eliminate pharmaceuticals from the water cycle, the effect UV-C irradiation is demonstrated on a laboratory scale. This method allows fast degradation of pharmaceuticals, which is exemplarily shown for the macrolide antibiotic erythromycin. Using the above HPLC-Q-TOF-MS method, concentration-time diagrams are obtained for the parent drug and their photodegradation products. After establishing the equations for first-order sequential reactions, computational fitting allows the determination of kinetic parameters, which might help to predict irradiation times and conditions when potentially considered as fourth stage within wastewater treatment.

We present a protocol for non-targeted analysis using time of flight mass spectrometry as a perfect tool to identify pharmaceuticals in waters. We demonstrate the application of UV irradiation for their elimination. Analysis involving irradiation, compound isolation, identification and kinetic modelling of the degradation profiles is illustrated.

Monitoring pharmaceuticals throughout the water cycle is becoming increasingly important for the aquatic environment and eventually for human health. ...

The Effect of Interfacial Chemical Bonding in TiO2-SiO2 Composites on Their Photocatalytic NOx Abatement Performance

The chemical bonding of particulate photocatalysts to supporting material surfaces is of great importance in engineering more efficient and practical photocatalytic structures. However, the influence of such chemical bonding on the optical and surface properties of the photocatalyst and thus its photocatalytic activity/reaction selectivity behavior has not been systematically studied. In this investigation, TiO2 has been supported on the surface of SiO2 by means of two different methods: (i) by the in situ formation of TiO2 in the presence of sand quartz via a sol-gel method employing tetrabutyl orthotitanium (TBOT); and (ii) by binding the commercial TiO2 powder to quartz on a surface silica gel layer formed from the reaction of quartz with tetraethylorthosilicate (TEOS). For comparison, TiO2 nanoparticles were also deposited on the surfaces of a more reactive SiO2 prepared by a hydrolysis-controlled sol-gel technique as well as through a sol-gel route from TiO2 and SiO2 precursors. The combination of TiO2 and SiO2, through interfacial Ti-O-Si bonds, was confirmed by FTIR spectroscopy and the photocatalytic activities of the obtained composites were tested for photocatalytic degradation of NO according to the ISO standard method (ISO 22197&#8722;1). The electron microscope images of the obtained materials showed that variable photocatalyst coverage of the support surface can successfully be achieved but the photocatalytic activity towards NO removal was found to be affected by the preparation method and the nitrate selectivity is adversely affected by Ti-O-Si bonding.

The Effect of Interfacial Chemical Bonding in TiO2-SiO2 Composites on Their Photocatalytic NOx Abatement Performance

The focus of the present work is to establish means to generate and quantify levels of Ti-O-Si linkages and to correlate these with the photocatalytic properties of the supported TiO2.

The chemical bonding of particulate photocatalysts to supporting material surfaces is of great importance in engineering more efficient and practical ...

A Facile Synthetic Method to Obtain Bismuth Oxyiodide Microspheres Highly Functional for the Photocatalytic Processes of Water Depuration

Bismuth oxyhalide (BiOI) is a promising material for sunlight-driven-environmental photocatalysis. Given that the physical structure of this kind of materials is highly related to its photocatalytic performance, it is necessary to standardize the synthetic methods in order to obtain the most functional architectures and, thus, the highest photocatalytic efficiency. Here, we report a reliable route to obtain BiOI microspheres via the solvothermal process, using Bi(NO3)3 and potassium iodide (KI) as precursors, and ethylene glycol as a template. The synthesis is standardized in a 150 mL autoclave, at 126 &#176;C for 18 h. This results in 2-3 &#181;m-sized mesoporous microspheres, with a relevant specific surface area (61.3 m2/g). Shortening the reaction times in the synthesis results in amorphous structures, while higher temperatures lead to a slight increase in the porosity of the microspheres, with no effect in the photocatalytic performance. The materials are photo-active under UV-A/visible light irradiation for the degradation of the antibiotic ciprofloxacin in water. This method has demonstrated to be effective in interlaboratory tests, obtaining similar BiOI microspheres in Mexican and Chilean research groups.

This article describes a synthetic method to obtain bismuth oxyiodide microspheres, which are highly functional to perform the photocatalytic removal of organic pollutants, such as ciprofloxacin, in water under UV-A/visible light irradiation.

Bismuth oxyhalide (BiOI) is a promising material for sunlight-driven-environmental photocatalysis. Given that the physical structure of this kind of ...

CO2 Photoreduction to CH4 Performance Under Concentrating Solar Light

We demonstrate a method for the enhancement of CO2 photoreduction. As the driving force of a photocatalytic reaction is from solar light, the basic idea is to use concentration technology to raise the incident solar light intensity. Concentrating a large-area light onto a small area cannot only increase light intensity, but also reduce the catalyst amount, as well as the reactor volume, and increase the surface temperature. The concentration of light can be realized by different devices. In this manuscript, it is realized by a Fresnel lens. The light penetrates the lens and is concentrated on a disc-shaped catalyst. The results show that both the reaction rate and the total yield are efficiently increased. The method can be applied to most CO2 photoreduction catalysts, as well as to similar reactions with a low reaction rate at natural light.

CO2 Photoreduction to CH4 Performance Under Concentrating Solar Light

We present a protocol for improving the performance of CO2 photoreduction to CH4 by heightening the incident light intensity via concentrating solar energy technology.

We demonstrate a method for the enhancement of CO2 photoreduction. As the driving force of a photocatalytic reaction is from solar light, the basic idea ...

Engineering

Developing Photosensitizer-Cobaloxime Hybrids for Solar-Driven H2 Production in Aqueous Aerobic Conditions

Developing photocatalytic H2 production devices is the one of the key steps for constructing a global H2-based renewable energy infrastructure. A number of photoactive assemblies have emerged where a photosensitizer and cobaloxime-based H2 production catalysts work in tandem to convert light energy into the H-H chemical bonds. However, the long-term instability of these assemblies and the need for hazardous proton sources have limited their usage. Here, in this work, we have integrated a stilbene-based organic dye into the periphery of a cobaloxime core via a distinct axial pyridine linkage. This strategy allowed us to develop a photosensitizer-catalyst hybrid structure with the same molecular framework. In this article, we have explained the detailed procedure of the synthesis of this hybrid molecule in addition to its comprehensive chemical characterization. The structural and optical studies have exhibited an intense electronic interaction between the cobaloxime core and the organic photosensitizer. The cobaloxime was active for H2 production even in the presence of water as the proton source. Here, we have developed a simple airtight system connected with an online H2 detector for the investigation of the photocatalytic activity by this hybrid complex. This photosensitizer-catalyst dyad present in the experimental setup continuously produced H2 once it was exposed in the natural sunlight. This photocatalytic H2 production by the hybrid complex was observed in aqueous/organic mixture media in the presence of a sacrificial electron donor under complete aerobic conditions. Thus, this photocatalysis measurement system along with the photosensitizer-catalyst dyad provide valuable insight for the development of next generation photocatalytic H2 production devices.

Developing Photosensitizer-Cobaloxime Hybrids for Solar-Driven H2 Production in Aqueous Aerobic Conditions

We have directly incorporated a stilbene-based organic dye into a cobaloxime core to generate a photosensitizer-catalyst dyad for photocatalytic H2 production. We have also developed a simple experimental setup for evaluating the light-driven H2 production by photocatalytic assemblies.

Developing photocatalytic H2 production devices is the one of the key steps for constructing a global H2-based renewable energy infrastructure. A number ...

Metal Oxide Heterojunction for Photocatalytic Activities

There is a significant global demand for improvements in synthesis techniques and their optimal characteristics, especially for industrial-scale applications. Sol-gel-based solution combustion synthesis (SG-SCS) is a simple method to produce ordered porous materials. In this regard, Pearson&#39;s hard and soft acids and bases theory assists in selecting host-dopant reactivity to form a proper heterojunction.
The formation of a heterojunction also changes the essential properties of the materials, improving photocatalysis via charge transfer or synergistic activities. A calcination temperature of 500 &#176;C is ideal for this process based on the results of the stability assessment via a differential thermogravimetry ratio analysis (DTG).
The nanoscale dimensions of the nanoparticles (NPs) and nanocomposites (NCs) generated were validated using X-ray diffraction and high-resolution transmission electron microscopy (HRTEM). Furthermore, the scanning electron microscopy micrographs and BET analyses confirmed the porosity nature of the materials. HRTEM, X-ray photoelectron spectroscopy, and energy-dispersive X-ray investigations established the materials composition. The study found that NCs degraded the acid orange 8 (AO8) color more efficiently than bare ZnO.

The development of a heterojunction boosts the photocatalytic activities of solution combustion synthesis, which is a time-/energy-efficient process. Advanced analytical characterization techniques were used in this protocol to evaluate the materials&#39; characteristics, and nanocomposites demonstrated improved acid orange-8 dye degradation.

There is a significant global demand for improvements in synthesis techniques and their optimal characteristics, especially for industrial-scale ...

LED-Based In Vitro Screening for Assessing Photoactivable Molecules in Bacterial Photodynamic Inactivation

The rise of multi-drug-resistant infections and the lack of new antibiotic classes have renewed interest in alternative therapies like photodynamic inactivation of bacteria (aPDI). This process involves the administration of a photosensitizer (PS) activated by a suitable visible light source, producing exacerbated levels of reactive oxygen species (ROS) that damage crucial cellular biomolecules, ultimately causing bacterial cell death. It is crucial to create standardized, easy-to-use, and reproducible initial tests to assess and compare the effectiveness of light-induced phototoxicity of potential photosensitizers. This study introduces a simple and efficient in vitro technique for assessing photodynamic activity against planktonic bacterial cells. By employing a 96-well microplate format along with a large LED panel, the system facilitates the systematic evaluation of various compounds. Such a configuration allows for high-throughput screening of potential photosensitizers in a controlled and consistent environment, simplifying the process of identifying promising candidates for further development. This flexible platform serves as an important step in advancing the development of innovative photodynamic therapies for managing antibiotic-resistant infections.

This protocol describes a straightforward and economical method for evaluating the effectiveness of potential photosensitizers in antibacterial photodynamic inactivation (aPDI), using a 96-well plate format combined with an LED panel light source. This approach enables the simultaneous testing of multiple experimental conditions, including different concentrations, compounds, and bacterial strains.

The rise of multi-drug-resistant infections and the lack of new antibiotic classes have renewed interest in alternative therapies like photodynamic ...

Biochemistry

Inactivation of Pathogens via Visible-Light Photolysis of Riboflavin-5&#8242;-Phosphate

Riboflavin-5&#39;-phosphate (or flavin mononucleotide; FMN) is sensitive to visible light. Various compounds, including reactive oxygen species (ROS), can be generated from FMN photolysis upon irradiation with visible light. The ROS generated from FMN photolysis are harmful to microorganisms, including pathogenic bacteria such as Staphylococcus aureus (S. aureus). This article presents a protocol for deactivating S. aureus, as an example, via photochemical reactions involving FMN under visible light irradiation. The superoxide radical anion (<img alt="Equation 1" src="/files/ftp_upload/63531/63531eq01v3.png" style="margin: auto;" />) generated during the FMN photolysis is evaluated via nitro blue tetrazolium (NBT) reduction. The microbial viability of S. aureus that is attributed to reactive <img alt="Equation 1" src="/files/ftp_upload/63531/63531eq01v3.png" style="margin: auto;" /> species was used to determine the effectiveness of the process. The bacterial inactivation rate is proportional to FMN concentration. Violet light is more efficient in inactivating S. aureus than blue light irradiation, while the red or green light does not drive FMN photolysis. The present article demonstrates FMN photolysis as a simple and safe method for sanitary processes.

Inactivation of Pathogens via Visible-Light Photolysis of Riboflavin-5&#8242;-Phosphate

Here, we present a protocol to inactivate pathogenic bacteria with reactive oxygen species produced during photolysis of flavin mononucleotide (FMN) under blue and violet light irradiation of low intensity. FMN photolysis is demonstrated to be a simple and safe method for sanitary processes.

Riboflavin-5&#39;-phosphate (or flavin mononucleotide; FMN) is sensitive to visible light. Various compounds, including reactive oxygen species (ROS), can ...

Bioengineering

Evaluation of the Efficacy of Organic Peroxyacids for Eradicating Dairy Biofilms Using an Approach Combining Static and Dynamic Methods

The presence of biofilms in the dairy industry is of major concern, as they may lead to the production of unsafe and altered dairy products due to their high resistance to most clean-in-place (CIP) procedures frequently used in processing plants. Therefore, it is imperative to develop new biofilm control strategies for the dairy industry. This protocol is aimed at evaluating the efficacy of organic peroxyacids (peracetic, perpropionic, and perlactic acids and a commercial peracetic acid-based disinfectant) for eradicating dairy biofilms using a combination of static and dynamic methods. All the disinfectants were tested on the strongest biofilm-producing bacteria in either a single or a mixed biofilm using the minimum biofilm eradication concentration (MBEC) assay, a static high-throughput screening method. A contact time of 5 min with the disinfectants at the recommended concentrations successfully eradicated both the single and mixed biofilms. Studies are currently ongoing to confirm these observations using the Center for Disease Control (CDC) biofilm reactor, a dynamic method to mimic in situ conditions. This type of bioreactor enables the use of a stainless-steel surface, which constitutes most industrial equipment and surfaces. The preliminary results from the reactor appear to confirm the efficacy of organic peroxyacids against biofilms. The combined approach described in this study may be used to develop and test new biological or chemical formulations for controlling biofilms and eradicating microorganisms.

This protocol describes an approach combining static and dynamic methods to evaluate the efficacy of organic peroxyacids for eradicating biofilms in the dairy industry. This approach may also be used to test the effectiveness of new biological or chemical formulations for controlling biofilms.

The presence of biofilms in the dairy industry is of major concern, as they may lead to the production of unsafe and altered dairy products due to their ...

A Complete Method for Evaluating the Performance of Photocatalysts for the Degradation of Antibiotics in Environmental Remediation

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