Preparation of Activated Carbon from Walnut Shell by Steam Activation

Abstract

The purpose of the present work is to study the feasibil ity of the production of active carbon from wlanut shell, which is an agricultural by-product of relatively large quantity and low price. The walnut shell was carbonized first, then activated by steam. The effects of activation conditions on the characteristics of the active carbons obtained were experimentally investigated. The results are as follows.1) From all the raw materials employed, carbonized material having a relatively uniform macro-pores could be produced, and these are rich in macro-pores of 1.0-2.5 x 10^-6 m in radius.2) Active carbon obtained from the steam activation process showed the maximum YSg-value (Samax) at activation temperature 1173 K (Fig.6), and by correlating steam quantity and activated time, Samax of the active carbon determined (Fig.7).3) From measurements of BET surface areas, these active carbons were found to be rich in micropores of 2 x 10^-9 m in radius.4) Active carbon samples are found to possess high micro- and macro-pore volume and negligible mesoporosity, i. e. assumption of a bidisperse structure is correct (Fig.11).5) From meas urements of amount adsorbed of hexane-benzene solutions, these active carbons were shown to be more effective in the adsorption quantity than the synthetic zeolite 5 A (Table 3).
From these results, it seems that the walnut shell can be reutilized as the raw material of active carbon.