The adsorption removal of tannic acid by regenerated activated carbon from the spent catalyst of vinyl acetate synthesis

Abstract

Activated carbon can remove humic acid organic pollutants to reduce trihalomethanes carcinogens generated in the chlorination disinfection process. In this study, regenerated activated carbon (RAC) was recycled from the spent catalyst of vinyl acetate synthesis via a thermal regeneration method. The influences of regeneration temperature and time on the regeneration rate and iodine adsorption value of the RAC samples were determined, the nitrogen adsorption isotherms and pore structure characteristics of RAC samples were characterised, and the effects of RAC additive amount, pH, adsorption temperature, and time on tannic acid removal rate were investigated. Results indicated that regeneration time and temperature presented pronounced influences on the regeneration rate and iodine adsorption performance of RAC samples. For the RAC sample optimally prepared at 900 °C for 2 h, the iodine adsorption value, BET surface area, and the regeneration rate were 817 mg/g, 1346 m2/g, and 65.9%, respectively. Under the optimal conditions including RAC additive amount of 3.5 g, temperature of 25 °C, adsorption time of 200 min and pH of 4.0, and tannic acid concentration of 50 mg/L, the tannic acid removal rate reached 89.96%. The adsorption kinetic characteristics for tannic acid onto RAC matched to Pseudo-second-order model, meanwhile the analysis of Boyd dynamic equation and Intraparticle diffusion model denoted the absorption process was mainly controlled by film diffusion. This work provides a technology aiming at the joint treatment of hazardous waste resources, which involve the regeneration activated carbon from spent catalysts and the absorption removal of tannic acid organic pollutants.

Keywords

• Spent catalyst
• Regenerated activated carbon
• Tannic acid
• Adsorption kinetics