Licorice residue and Pistachio-nut shell mixture: A promising precursor for activated carbon

As a continuation of previous research concerning preparation of activated carbon from agricultural by-products, applying a mixture of two kinds of lignocellulosic by-products with complementary properties as the parent material is investigated. Two kinds of activated carbons are prepared by chemical activation of the parent mixture – including residues of licorice and pistachio-nut shells – with H3PO4 and ZnCl2 solutions, separately. The produced activated carbons have the surface areas comparable to the commercial ones. The lower ash content, higher bulk density and surface area of mix-based activated carbons in comparison with licorice-based ones, and also the highest mercury adsorption capacity of the mix-based ones confirm that it would be possible to modify the properties of an activated carbon using several complementary raw materials. The comparison of mercury adsorption capacities among mixed-based and the commercial activated carbons reveals that mix-based ones are effective and economical adsorbents for industrial wastewater treatment.