Feasible treatment of epoxy methyl ester wastewater using activated carbon as an adsorbent

A feasible method for treatment of wastewater generated during epoxy methyl ester production was provided in this study, which consisted of four parts, i.e., neutralization, heat pump distillation, evaporation crystallization, and adsorption. For this treatment process, adsorption was a key step. The major pollutants of epoxy methyl ester wastewater after neutralization and distillation were determined as methanol, ethyl alcohol and epoxy propane. Activated carbon was used as an adsorbent for the wastewater treatment and the adsorption behavior was mainly studied. The adsorption experiments of methanol as the model compound to actual wastewater using virgin activated carbons (VAC) and HNO3modified activated carbons (MAC) were carried out. FTIR and Boehm titration results indicated the increased oxidation groups were obtained through modification. Several isotherm and kinetic models were adopted to fit the experimental data by non-linear regression method. Results showed that Langmuir isotherm and pseudo-second order kinetic models can well describe the adsorption behavior. Various thermodynamic parameters such as standard free energy (ΔG0), enthalpy (ΔH0), and entropy (ΔS0) showed that the adsorption of methanol onto carbon was favored at lower temperature. In addition, breakthrough curves were determined using the column adsorption, which were fitted well by the Thomas model. Furthermore, the COD of initial actual wastewater (about 35000 mg/L) was significantly reduced to 293 mg/L after treatment. Finally, regeneration experiments demonstrated the potential of this method.