Activated carbon prepared from coffee pulp: potential adsorbent of organic contaminants in aqueous solution

Abstract

The processing of coffee beans generates large amounts of solid and liquid residues. The solid residues (pulp, husk and parchment) represent a serious environmental problem and do not have an adequate destination. In this work, activated carbons (AC) for adsorption of organic compounds were prepared from coffee pulp by controlled temperature at different pulp/Na2HPO4 ratios (4:1, 2:1, 5:4 and 1:1). The N2 adsorption/desorption isotherms showed AC with high quantities of meso and micropores and specific surface areas of 140, 150, 450 and 440 m2 g1 for AC 4:1, AC 2:1, AC 5:4 and AC 1:1, respectively. The prepared material AC 5:4 showed a higher removal capacity of the organic contaminants methylene blue (MB), direct red (DR) and phenol than a Merck AC. The maximum capacities for this AC are approximately 150, 120 and 120 mg g1 for MB, DR and phenol, respectively. Thus, a good adsorbent was obtained from coffee pulp, an abundant Brazilian residue.