Efficient photocatalytic degradation of metronidazole in wastewater under simulated sunlight using surfactant- and CuS-activated zeolite nanoparticles.

Hexadecyltrimethylammonium-bromide-activated zeolite nanoparticles coated with copper sulfide (ZEO/HDTMA-Br/CuS) was evaluated as a photocatalyst under sunlight for the degradation of metronidazole (MET). The surface and structural characteristics of ZEO/HDTMA-Br/CuS and other materials used in this study were analyzed using field emission-scanning electron microscopy, Fourier transform infrared and ultraviolet-visible diffuse reflectance spectroscopies, X-ray diffraction, Brunauer-Emmett-Teller surface area and Barrett-Joyner-Halenda pore size and volume analyses, and pH of zero charge test. ZEO/HDTMA-Br/CuS exhibited excellent surface and structural catalytic properties. For a comprehensive study of the degradation process, several parameters, such as the pH (3-11), MET concentration (10-30 mg/L), ZEO/HDTMA-Br/CuS dose (0.005-0.1 g/L), reaction time (5-200 min), and H2O2 concentration (50-200 mg/L), were optimized. ZEO/HDTMA-Br/CuS achieved 100% degradation efficiency when 10 mg/L MET was used under the optimum conditions: pH = 7, ZEO/HDTMA-Br/CuS dose = 0.01 g/L, and reaction time = 180 min. The degradation efficiency increased when the concentration of H2O2 was increased from 50 to 150 mg/L and decreased with further increase to 200 mg/L, indicating that the efficiency of MET degradation highly depends on the concentration of H2O2 in an aqueous solution. The degradation kinetics analysis revealed that the degradation is of the pseudo first-order. Thus, ZEO/HDTMA-Br/CuS proved to be an exceptional catalyst for the photodegradation of MET in aqueous media.

Statistical modeling optimization for antibiotics decomposition by ultrasound/electro-Fenton integrated process: Non-carcinogenic risk assessment of drinking water.

The present work proposes an ultrasound (US) assisted electro-Fenton (EF) process for eliminating penicillin G (PNG) and ciprofloxacin (CIP) from aqueous solutions and the process was further optimized by response surface methodology (RSM)- Box-Behnken design (BBD). The impact of pH, hydrogen peroxide (H2O2) concentration, applied voltage, initial pollutant concentration, and operating time were studied. The capability application of the electro-Fenton (EF) and US processes was compared separately and in combination under the optimum conditions of pH of 4, a voltage of 15 V, the initial antibiotic concentration of 20.7 mg/L, H2O2 concentration of 0.8 mg/L, and the operating time of 75 min. The removal efficiency of PNG and CIP using the sono-electro-Fenton (SEF) process, as the results revealed, was approximately 96% and 98%, respectively. The experiments on two scavengers demonstrated that ⦁OH contributes significantly to the CIP and PNG degradation by SEF, whereas ⦁O-2 corresponds to only a negligible amount. The total organic carbon (TOC) and chemical oxygen demand (COD) analyses were used to assess the mineralization of CIP and PNG. The efficiency of COD and TOC removal was reached at 73.25% and 62.5% for CIP under optimized operating circumstances, and at 61.52% and 72% for PNG, respectively. These findings indicate that a sufficient rate of mineralization was obtained by SEF treatment for the mentioned pollutants. The reaction kinetics of CIP and PNG degradation by the SEF process were found to follow a pseudo-first-order kinetic model. In addition, the human health risk assessment of natural water containing CIP and PNG that was purified by US, EF, and SEF processes was done for the first time. According to the findings, the non-carcinogenic risk (HQ) caused by drinking purified water by all three systems was calculated in the acceptable range. Thus, SEF is a proper system to remove various antibiotics in potable water and reduces their human health risks.

Efficient purification of aqueous solutions contaminated with sulfadiazine by coupling electro-Fenton/ultrasound process: optimization, DFT calculation, and innovative study of human health risk assessment.

In the current work, the hybrid process potential of ultrasound (US) and electro-Fenton (EF), named sono-electro-Fenton (SEF), was fully investigated for sulfadiazine (SDZ) degradation. The decontamination in the integration approach was revealed to be greater than in individual procedures, i.e., EF process (roughly 66%) and US process (roughly 15%). The key operating process factors (i.e., applied voltage, H2O2 content, pH, initial concentration of SDZ, and reaction time) affecting SDZ removal were evaluated and optimized using Box-Behnken Design (BBD). In addition, an adaptive neuro-fuzzy inference system (ANFIS) as an efficient predictive model was applied to forecast the decontamination efficiency of SDZ through the SEF process based on the same findings produced from BBD. The results revealed that the predictability of SDZ elimination by the ANFIS and BBD approaches exhibited an excellent agreement (a greater R2 of 0.99%) among the both models. Density functional theory was also employed to forecast the plausible decomposition elucidation by the bond-breaking mechanism of organic substances. Plus, the main side products of SDZ degradation during the SEF process were tracked. Eventually, the non-carcinogenic risk assessment of different samples of natural water containing SDZ that was treated by adopting US, EF, and SEF processes was examined for the first time. The findings indicated that the non-carcinogenic risk (HQ) values of all the purified water sources were computed in the permissible range.