Kinetics of Fenton Like Cotton Reactive Dyeing Wastewater Discoloration Process

Textile dyeing processes are responsible for the colour of the textile wastewater, major environmental problems for the textile sector. In order to meet legislative requirements, coloured wastewaters have to be treated. Oxidative treatments proved to be among the most efficient and one of the most effective oxidation agents is the hydrogen peroxide. In this paper the kinetics of the colour removal of wastewater produced in the reactive dyeing of cellulose fibers when using a Fenton like system (hydrogen peroxide - CuO/Al2O3 catalyst) was investigated. Different dyes and dyeing concentrations are tested, and chemical oxygen demand decrease is monitorised as well. The results are compared with those obtained when using a classical Fenton process for removing the colour of the wastewater. Plotting ln(C-0/C-t) versus time for each of the studied reactive dyes linear dependencies have been obtained, leading to the conclusion that the process follows a pseudo-first order kinetic model at each pH. The rate constant at different pH values and the half-life were calculated as well. Regression analyses conducted to a model of the process that match well with experimental data.