Application of phosphorus containing ZnO microparticles in water treatment through photocatalytic degradation of contaminants under visible light radiation

The water treatment is one of the most critical issues worldwide because of thepopulation growth and environmental problems [۱]. There are advanced technologies used forthe water treatment. One of these technologies is the photocatalytic degradation of organicpollutants using photocatalysts such as ZnO that nowadays are widely used because of theirvisible light absorbance ability and low costs [۲,۳]. Photocatalysts are semiconductor solidoxides which can create electron-hole pairs upon light absorption. These electron-hole pairs reactwith existing materials at the surface and oxidize them to low-risk materials [۴]. Thephotocatalytic activity of the photocatalyst containing ۱.۸ wt.% of phosphorus, i.e. P-ZnO۱.۸%sample, was evaluated for the degradation of Rhodamine B (RhB) under visible light irradiation.The parameters such as pH, catalyst dosage, contaminant concentration and effect of persulfateas an oxidant were studied. It was found that the P-ZnO۱.۸% photocatalyst could destroy ۹۹% ofRhB (۵ ppm) in ۱۸۰ min at pH=۷; furthermore, it degraded ۱۰۰% of ۵ and ۱۰ ppm of the RhBpollutant in ۱۲۰ and ۱۸۰ min, respectively, only by adding ۰.۰۱ g of persulfate into the reactionsolution. According to the reusability test, it was proved that after five cycles, the catalystactivity was not highly changed and it was potentially capable of pollutant degradation.