A series of activated carbons with high surface
area were prepared from walnut shell using chemical
activation with ZnCl2. In this research the carbonization
stage was carried out at 500°C. The performance of the
synthesized carbons evaluated in adsorption of benzene
and toluene from waste gas. The influence of impregnation
ratio on the characteristics of synthesized activated carbons
as well as their adsorption capacity was investigated. The
ratio of activation agent to walnut shell was selected in the
range of 0.5–2.0 wt/wt. The synthesized activated carbons
were characterized using XRD, SEM, BET and FTIR
techniques. The highest activated carbon production yield
was obtained at impregnation ratio of 1.5 wt/wt. The XRD
analysis illustrated that peaks intensity decreased with
increasing impregnation ratio showing that amorphous
property of samples was increased. The SEM analysis
revealed successful pore development in synthesized
activated carbons obtained at high impregnation ratios.
The surface area of the activated carbons increased with
increasing impregnation ratio and its maximum value
reached 2643 m2·g–1 at impregnation ratio of 2/1. FTIR
analysis indicated that the relative amount of different
acidic surface groups on synthesized carbons was a
function of impregnation ratio. Experimental results for
benzene and toluene adsorption showed a high potential of
employing synthesized impregnated activated carbon for
treatment of waste gas. Generally, the amount of VOC
adsorbed on the surface was affected by physicochemical
properties of synthesized activated carbons.