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

This paper provides a complete process for evaluating the catalytic performance of semiconductor catalysts in the laboratory to develop semiconductor catalysts with potential for practical applications. The advantage of this technique is that the photocatalytic performance of semiconductor catalysts can be evaluated in the laboratory in a more comprehensive manner. Demonstrating the procedure will be Bing Wang, a PhD student from the laboratory of Zhuo Li.And XuXia Zhang, LeCheng Li, MengTing Ji, Zheng Zheng, ChuanHui Shi, master students from the laboratory of Zhuo Li.To begin, prepare the reaction solution by dissolving six grams of ammonium nitrate in 200 milliliters of deionized water and treat with ultrasonic waves at 40 kilohertz frequency, 300 watt power for five minutes in one cycle to dissolve it completely then put it into a 500 milliliter volumetric flask to fix the volume.

Add 2, 526 milliliters of deionized water to a beaker and then add 180 milliliters of ammonium nitrate solution, 54 milliliters of sodium hydroxide solution, and 120 milliliter of silver nitrate solutions sequentially to the beaker. Stir the solution vigorously for 10 minutes to prepare the diammine silver one complex. Finally, add 120 milliliters of potassium hydrogen phosphate solution to the complex and stir for five minutes.

After the color of the solution changes from colorless to light yellow the precipitate obtained is silver phosphate rhombic dodecahedral. Separate the resulting precipitate by centrifugation at 7, 155 point 5G for 10 minutes at room temperature. Subsequently, centrifuge at three times with 50 milliliters of deionized water in the same conditions.

Store the rhombic dodecahedral silver phosphate at room temperature in a dry environment away from light. Dissolved 5.77 milligrams of bromine subphthalocyanine in 50 milliliters of ethanol in a glass beaker and dissolve completely by sonication at 40 kilohertz frequency 300 watt power in one cycle for 30 minutes at room temperature. Then add 144.25 milligrams of silver phosphate to the above solution and sonicate at 40 kilohertz frequency, 300 watt power in one cycle for 30 minutes at room temperature.

Stir the above solution in an 80 degrees Celsius water bath to allow complete evaporation of the ethanol. Dry the resulting brownish yellow powder overnight in an oven at 60 degrees Celsius and name the prepared sample as bromine subphthalocyanine silver phosphate For the test solution, 10 milligrams of tetracycline were dissolved in 500 milliliters of distilled water to obtain a 20 PPM solution. Then transfer 50 milliliters of the test tetracycline solution to a glass photocatalytic reactor.

Stir the solution thoroughly with a magnetic stir at 1000 rpm, and maintain the temperature at 25 degrees Celsius. Then turn the air pump switch on and add the air to the solution at a rate of 100 milliliters per minute to obtain air saturation. Add 50 milligrams of the prepared photo catalyst to the test solution to reach a concentration of one gram per liter.

Take the first sample immediately using a glass syringe. After stirring for 30 minutes in the dark, take the second sample and turn on the light source After a radiation for different time intervals, filter all the extracted samples through a 0.22 micrometer nylon membrane to remove solid particles before analysis. Store the filtered samples away from light in five milliliters centrifuge tubes until analysis.

Measure the concentration of tetracycline with a UV visible spectrophotometer at 356 nanometers and evaluate the photocatalytic effect by the degradation rate as described in the manuscript. The SEM analysis shows that the average diameter of the rhombic dodecahedral structure was found to be between two to three micrometers, while bromine subphthalocyanine microcrystals show a large irregular flake structure. The photocatalytic activity of silver phosphate showed only 72.86%while bromine subphthalocyanine silver phosphate demonstrated 94.54%degradation of tetracycline after 30 minutes of visible light to radiation.

The degradation rate constant by composites was 1.69 times higher than that of the silver phosphate. After five cycles, the composite showed a high tetracycline removal rate of 77.5%However, it decreased from 72.86%to 20.84%by silver phosphate. The XRD analysis of the composite showed that the peaks of the cycled samples did not change compared with the original samples, indicating good stability of the composite.

Photocatalytic degradation shows that the absorption and removal of tetracycline increased as the photocatalyst concentration in the reaction solution increased. The effect of pH on the photocatalytic degradation of the composite material to remove tetracycline was slightly reduced in acidic solutions while more attenuated in neutral and alkaline solutions. The addition of anions had an inhibitory effect on the photocatalytic degradation of tetracycline, but the degradation rate was not overly affected.

The effect of temperature on photocatalytic degradation for 30 minutes shows that the degradation rate of tetracycline gradually increased with the increase in temperature. Remember to turn on the circulating water switch to control the temperature at 25 degrees Celsius when performing the photocatalytic experiment.