Abstract:
The Fenton process is widely recognized for its efficiency in advanced oxidation of wastewater; however, its large-scale application is hindered by the need for an acidic
pH to prevent metal precipitation. In this study, a novel Fenton-like process was developed using CuII complexes with aminopolycarboxylic acids such as NTA, EDDS, and IDA as chelating agents to stabilize copper. This system was employed as a catalyst for the activation of hydrogen peroxide (H2O2) and peroxymonosulfate (PMS, HSO5 −) to degrade sulfamethoxazole (SMX) in a neutral aqueous medium. The first part of the research involved synthesizing and characterizing CuII-based organic complexes (CuII-NTA, CuII-EDDS, CuII-IDA) in aqueous solutions using UV-Visible spectrophotometry. The results confirmed that these complexes remained stable in the dark and at room temperature. The findings revealed that neither the CuII-L/H2O2 nor CuII-L/PMS systems effectively degraded SMX. This inefficiency was attributed to the slow redox cycle of CuII-L/CuI-L, which limited the generation of reactive radicals. To enhance this process, the addition of hydroxylamine (HA) facilitated the reduction of CuII to CuI, thereby promoting continuous radical production through the decomposition of H2O2 or PMS. In-depth kinetic studies were conducted under varying experimental conditions, examining the effects of initial concentrations, pH, CuII:L molar ratio, and reaction temperature. Additionally, the influence of metal ions and different inorganic anions was investigated. The mechanistic aspects of the system were also explored, focusing on the role of oxygen and reactive radicals in the modified Fenton-like processes. The results suggest that the modified Fenton-like process, catalyzed by CuII-L complexes, is a promising and effective approach for the removal of antibiotics, such as sulfamethoxazole, from contaminated water.
