Simultaneous removal of 3d transition metals from multi-component solutions by activated carbons from co-mingled wastes

Abstract

The main purpose of the present work was to study the simultaneous removal of 3d transition metals from multi-component solutions by novel porous material obtained from carbon-containing liquid and solid waste. The activated carbon was prepared from co-mingled natural organic waste: 25% sunflower husks, 50% petroleum waste and 25% low-grade bituminous coal. The porous carbon material was obtained via stages of pre-oxidation with binary eutectic Na/K carbonates (in order to avoid melting and coke formation), followed by “step by step” carbonization at 100–400 °C in an inert atmosphere and activation with steam at 850 °C. The adsorption of the 3d transition metals: copper (II), cobalt (III), nickel (II), iron (III), and chromium (III), on novel activated carbons has been investigated using multi-component model solutions. Experiments have been carried out on the thermodynamics of the simultaneous adsorption of the 3d transition metals in a static mode. The total metal removal combines the process of metal hydroxide precipitation in the solution with the metal cation adsorption on negatively charged carbon surface in a single operation unit. The carbon/metals interaction at the surface of spent adsorbents is discussed.