Degradation kinetics of Jean-wash-wastewater by using Electro-Fenton system with an effective biochar cathode thermally modified by CO2

Abstract

The degradation kinetics of dye and Total Organic Carbon (TOC) in jeans-wash-wastewater (JWW) were investigated in an Electro-Fenton (EF) system using an effective biochar cathode thermally modified by CO2. The kinetic data of dye and TOC degradation reaction were obtained at ambient temperature and fitted to kinetic models with different orders (alpha,beta) depending on the initial concentration ratio of generated hydroxyl radicals (OH center dot) to concentration of pollutant (M and M =2-10). To estimate the most appropriate kinetic model, nine kinetic models named from Case 1-9 were proposed with different reaction orders (alpha, beta = 0,1,2). These models were examined in two stages for both dye and TOC (Stage I-II) as their degradation reaction rates were different at the beginning of the reaction and during the rest of the reaction. The study found that different kinetic models were compatible with the experimental model for each stage of TOC and dye. While the minimum M values for the dye degradation were 8 in Stage I and 4 in Stage II, the minimum M values for the TOC degradation were 5 in Stage I and 3 in Stage II for Case 4 and Case 8 theoretical models, respectively. The kinetic study showed that quantity of OH center dot in the EF systems is very effective to determine the kinetic models and a specific value of minimum OH center dot concentration is required to degrade each type of wastewater.