Degradation of organic pollutant in restaurant wastewater using the homogenous catalysis with Mn(II) and EDTA

Abstract

It can be seen that the objects of wastewater that need to be treated are quite diverse in types and complex in terms of reaction mechanisms. The methods mainly focus on the treatment of toxic organic compounds, especially phenols or plant protection agents in industrial wastewater, paper industry, food production, textile industry, printing industry... The activation of H₂O₂ and O₂ by complexes of transitional metal ions and suitable ligands creates oxidizing agents and ecologically healthy products. The intermediate substances arising in the activation process such as free radicals OH^., O₂^., HO₂^., ... can oxidize many compounds, especially the ability to attack the aroma of organic pollutants. In this paper, the results of research on treating organic pollution in restaurant wastewater with H₂O₂ are presented as a catalyst of complexes between Mn²⁺ ions and EDTA. The conditions including pH, EDTA/Mn²⁺, the concentration of H₂O₂, Mn²⁺ were investigated to obtain the optimum conditions for improving COD treatment efficiency. This work proposes a method based on formation of the Mn(II)-EDTA complex,  b=1; with the optimal conditions of other factors as following [H₂O₂]₀ = 0,75.10^-3 mol/L; [Mn(EDTA)]²- = 33,33 mol/L, pH=10.5; t = 15 minutes. The initial COD of 1025 mg/L decreased to 135 mg/L after the proposed procedure.  The results provide solutions of homogeneous complex catalysts for domestic/restaurant and industrial wastewater treatment at room temperature and atmosphere.