A clean process for activator recovery during activated carbon production from waste biomass

Chemical activation is a widespread method for activated carbon (AC) preparation, but the removal and recycle of activator from the carbon product are generally a nuisance process. In this study, an environmental benign process, called modified vacuum pyrolysis (MVP) process, was developed for AC production and simultaneous recovery of the activator. The process included two steps: (1) carbonization and activation stage in a vacuum condition; (2) zinc recovery stage in a special temperature and pressure range. In the MVP process, over 99.99 % of the zinc used for activation was recovered in the form of zinc chloride and metallic zinc. The resultant ACs with basic and hydrophobic surface properties displayed higher adsorption capacity for phenol than that of carbons obtained by traditional pyrolysis method. The main merit of the MVP process was that there was no wastewater generation during the whole procedure. Consequently, the experimental data obtained in the present study provided scientific basis for zinc chloride recovery by vacuum pyrolysis during ACs production process. (C) 2011 Elsevier Ltd. All rights reserved.