Preparation of carbon materials from chromium-tanned leather shavings for the removal of dyes from aqueous solution

Abstract

"Chromium-Tanned Leather Shavings are hazardous residues generated during leather processing. Since they contain considerable amounts of chromium, they represent a threat to life and the environment if managed improperly. The present study examines the transformation of such residues into carbon adsorbents and their use in the removal of azo dyes (methylene blue, Congo red and acid black 210) from water. The effects of temperature, holding time and the presence of an activating agent were studied, and basic characterization of the produced materials was performed. Carbon materials contain a low amount of chromium and an improved surface area that was only developed when high temperatures and an activating agent were employed. Depending on the synthesis conditions, the adsorbents’ surface charge was positive or negative, which impacts the dye uptake from aqueous solution. Both the chemical speciation of the dye and the material´s pore volume played a critical role during the adsorption process. It is possible to obtain carbon materials from Chromium-Tanned Leather Shavings, containing no hazardous chromium(VI) particles, that are capable of removing polluting dyes from water."