Preparation Of Ceramsite Based On Clay And Its Adsorption Study For Heavy Metal Ions

For their special structure, good adsorption and ion exchange properties, low prices and abundant reserves, clay adsorbents show broad application prospects in many areas as wastewater treatment. But directly using clay powder or modified clay water treatment could easily lead to secondary pollution and not conducive to recycle. Along the research ideas to modify natural clay material or design assembled superior performance as the adsorption material. In view of all above problems, in this study, clay was used as aggregate, adding inorganic as pore-forming agent, sintering ceramic at lower temperature to receive excellent performance, low-cost adsorption and recycle- able materials. Ceramic properties were studied, as well as modified ceramic and its application on the adsorption of heavy metal ions.Clay as aggregate, pulverized coal (5%) and graphite (15%) composite as pore-forming agent, 1.5% vermiculite as modifier, porous ceramic clay sintered successfully, apparent porosity is 67.87%, the volume density reaches 0.93g/cm3. Performance is impacted by the pore-forming agent types, complex pore- forming agent ratio and vermiculite agent. With an increase of the amount of graphite, porosity significantly first increases then begins to reduce, bulk density showes the opposite trend. Vermiculite adding can compensate for part of the ceramic volume contraction, improve shapes and structure of pore, improve porosity, lower bulk density and improve the rate of powder resistance. With low density, high porosity and rough surface, porous ceramic based clay have better adsorption properties body of heavy metal ions like Cu2+, Pb2+ and Cd2+ in sewage. Adsorption process includes the outside surface adsorption and equilibrium adsorption, which begins with high adsorption rate and reachs equilibrium within certain period of time. -OH and C-O in ceramic participate in the adsorption process and a new phase forms, the very structure of ceramic hasn't been destroyed. Cu2+ adsorption kinetics is more consistent with Freundlich equation, adsorption reactions are multi-layer adsorption. The Pb2+ and Cd2+ adsorption processes more in line with Quasi-two adsorption rate equation and Intragranular transport model, which means the adsorption process includes chemical adsorption and controls by several steps.