Azithromycin decomposition from simple and complex waters by H2O2 activation over a recyclable catalyst of clay modified with nanofiltration process brine

In the current research, the brine of desalination units on the Persian Gulf coast was used to improve the catalytic properties of clay. The catalyst was used to degrade azithromycin through H2O2 activation. The catalyst construction was optimized by considering the furnace retention time (60, 120, 180, 240 min), calcination temperature (200, 300, 400, 500 °C), and the ratio of brine-to- distilled water (100:0, 50:50, 25:75, 0:100%v/v). The catalyst was crystalline and mesoporous and had an area of 11.52 m2/g. The maximum azithromycin decontamination (96.50%) was achieved at pH 5.0, catalyst dose of 5 g/L, hydrogen peroxide quantity of 2%v/v, and contact time of 60 min. Azithromycin decomposition kinetics using the system followed the first-order model (R² >0.96). Based on the study of scavengers, hydroxyl radicals played a vital role in the process. The catalyst had good stability and in the seventh cycle of reuse, it had an efficiency of 54%. Phosphate anion and aluminum cation had more interference effects on the azithromycin removal. The removal of azithromycin in the presence of humic acid and fulvic acid decreased and reached 80.25 and 83.59%, respectively. The azithromycin removal from environments like distilled water, municipal tap water, sewage, and urine was tested, and the efficiency was the lowest in sewage. The catalyst of this work could be effectively applied for H2O2 activation and, eventually, antibiotic degradation from many mediums.