Degradation of atrazine by modified stepwise-Fenton’s processes

• Published in: Chemosphere (Oxford) Vol. 67; no. 4; pp. 755 - 761
• Main Authors: Chu, W., Chan, K.H., Kwan, C.Y., Choi, K.Y.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.03.2007; Elsevier
• Subjects: Agronomy. Soil science and plant productions; Applied sciences; Atrazine; Atrazine - chemistry; Biological and medical sciences; Biological and physicochemical phenomena; chemical degradation; chemical reactions; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Environmental Restoration and Remediation - methods; Exact sciences and technology; Fenton; Fenton's reaction; Ferrous Compounds - chemistry; free radicals; Fundamental and applied biological sciences. Psychology; H 2O 2; Herbicides - chemistry; hydrogen peroxide; Hydrogen Peroxide - chemistry; hydroxyl radicals; iron; Kinetic model; Kinetics; Models, Chemical; Natural water pollution; oxidation; Oxidation-Reduction; Pollution; Pollution, environment geology; reaction kinetics; Soil and water pollution; Soil Pollutants - chemistry; Soil science; Stepwise dosage; Water treatment and pollution; H 2O 2; Kinetic model; Fenton; Stepwise dosage; Atrazine; Hydrogen peroxide; Pesticides; Endocrine disruptor; Concentration; Chemical degradation; H2O2; Chemical reaction kinetics; Herbicide; Operating conditions; Decontamination; Sequential method; Chemical treatment; Triazine derivatives; Process modification; Fenton reaction; Water pollution; Organic compounds
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2006.10.039

The removal of atrazine (ATZ) by stepwise Fenton’s processes (stepwise-FP) was studied and the system models were developed through the examination of reaction kinetics. The study compared the performance of the removal of ATZ by conventional FP with stepwise-FP, where the total dose of H 2O 2 was split and inputted into the system at different times and/or quantities. The performance of stepwise-FP was found to be better than that of conventional FP. This was probably due to the minimization of the peak concentration of H 2O 2 in the solution, which reduced the probability that valuable H 2O 2 and hydroxyl radicals would be consumed in forming weaker radicals. The reaction kinetics of the decay of ATZ in stepwise-FP was found to be a two-stage process; and in each stage, fast decay followed by stagnant decay was observed. Two characterized constants (the initial decay rate and the oxidative capacity) were introduced and were found to be useful in quantifying the stepwise-FP. The models for predicting stepwise-FP with respect to different dosing times and/or asymmetrical doses were developed, and were found to be very useful for evaluating the system performance and/or for process design.