Enhanced Copper (II) Removal from Acidic Water By Granular Activated Carbon Impregnated with Carboxybenzotriazole

Under acidic conditions (<pH 4.0) common granular activated carbons (GACs) exhibit declining affinity and capacity for many heavy metal cations in treating industrial wastewaters. The adsorption capacities of four types of granular activated carbon (GACs) were significantly increased by oxidation with boiling nitric acid. Column and breakthrough experiments results demonstrated that carboxybenzotriazole (CBT) enhanced the ability of activated carbon to sequester copper to remarkable level: up to 10% by mass. Hard and soft acid/base behavior (HSAB), metal stability and complexation constants, benzotriazoles dissociation constants and point of zero charge for the carbon, as well as triazole precipitation on the GAC surface were attributed to the differences in metal affinity and associated immobilization potential.