Sulfamethazine (SMT) is an antibiotic with good antimicrobial effect and is widely used to treat human and livestock diseases. Though the degradation of SMT by the conventional Fenton and electro-Fenton (EF) processes is efficient, it is limited by a narrow pH and iron sludge generation. Herein, we constructed a cost-effective EF system with the synergistic effect of zero-valent iron (Fe0) and sulfite (Fe0-EF/Sulfite), and key parameters such as applied current, catalyst dosing, sulfite dosage, and initial pH were optimized. Under the optimal conditions (Fe0dosing of 50 mg/L, sulfite dosage of 1.5 mM, current of 40 mA, and pH of 3), the removal efficiency of 10 mg/L SMT reached 100% within 30 min, and the degradation rate constant reached 0.194 min−1. Electron paramagnetic resonance (EPR) analysis and quenching experiments confirmed the generation of various reactive oxygen species (ROS), such as•OH, SO4−, O2−, and1O2, which significantly improved the pollutant removal efficiency. Sulfite accelerated iron cycling and inhibited the formation of iron sludge, thus broadening the pH range of the reaction from three to eight and overcoming the limitations of the conventional EF process. The Fe0-EF/Sulfite system performs cost-effectively at a wide pH range, providing an efficient and low-carbon solution for environmental pollution remediation with broad application prospects.
Hongbo Fang,Liqian Dai,Shuyan Wang,Weiye Shi,Defang Ma
The permanganate/bisulfite (PM/BS) process is highly efficient in the oxidation of refractory contaminants due to the generation of a large number of reactive manganese species and radicals. However, a lot of concerns need to be addressed for the application of the PM/BS process in real sulfamerazine (SMZ) contaminated water treatment. The factors affecting the degradation efficiency of SMZ by PM/BS and the influences of PM/BS pre-oxidation on the formation and toxicity of trihalomethanes (THMs) during the subsequent chlorination of simulated SMZ-contaminated waters were investigated in this study. The PM/BS process exhibited fast oxidation of SMZ at acidic/neutral pH and low SMZ concentration (5 μm) with more than 80% of SMZ removal within 15 s. The permanganate was efficiently activated by bisulfite and exhibited high efficiency in SMZ degradation when permanganate/bisulfite dosage was 50 μm:250 μm. The co-existing protein bovine serum albumin caused less than 10% inhibition of SMZ degradation in the PM/BS process at pH 6 and 7. However, humic acids and alginate inhibited the removal of SMZ by 18%–57%. PM/BS pre-oxidation of SMZ-contaminated waters achieved a 28%–64% reduction of THM formation in the subsequent chlorination, greatly decreasing the toxicity risk in chlorination.
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