Functionalized granular activated carbon and surface complexation with chromates and bi-chromates in wastewater

► Physico-chemical adsorption using functionalized activated carbon (FACs) is applied. ► FACs have hydrophilic, acidic external surface with functional surface sites. ► FACs make surface complexes easily with CrO42 − and HCrO4−. ► Surface complex formation is maximized in the order FAC-HNO3 > FAC-HF > FAC-HCl. ► Pseudo kinetic, intra-particle pore and film diffusion models are applied.