Optimization of metal component, characterization, and stability of Cu/Mg/Al–chitosan catalyst in catalytic ozonation of a landfill leachate

摘要

The aim of this work was to optimize the metal components of the Cu/Mg/Al-chitosan catalyst for the treatment of a landfill leachate during a catalytic ozonation process. A central composite design with response surface methodology was applied to assess the relationships between the value of Mg, Cu, and Al in the Cu/Mg/Al-chitosan catalyst and chemical oxygen demand (COD) removal from the landfill leachate and identify the optimum conditions. Quadratic model for three variables proved to be significant with very low probabilities (<0.0001). The optimum metal content for synthesis of the Cu/Mg/Al-chitosan was determined as Mg = 4 mmol/L, Cu = 0.89 mmol/L, and Al = 2 mmol/L. A confirmation run gave 81.35% of COD removal compared with 79.89% of predicted value. Results showed that the magnesium metal in the catalyst was more effective in COD removal than other metals. After a 50-min reaction time, the COD removal percentage of 49, 61, and 78 was attained for the landfill leachate with initial pH of 5.5, 7.3, and 9.1, respectively. The recyclability test indicated that the optimized catalyst could be efficiently utilized three times with COD removal efficiency of 81.35%, 66%, and 50%. The X-ray powder diffraction and electron dispersive spectroscopy tests confirmed the successful modification of chitosan with Mg/Cu/Al. The findings of this study demonstrate the applicability of Cu/Mg/Al-chitosan for eliminating COD from the leachate of sanitary landfill.