Preparation And Application Of Coal-based Microfiltration Carbon Membranes

Coal-based carbon membrane, as a novel porous inorganic membrane, is usually prepared by the carbonization of coal as precursor. It attracts more and more attention in the field of liquid separation due to low cost, thermal and chemical stability and high mechanical strength etc. Moreover, coal-based carbon membrane has electric conductivity. The electro-catalytic membrane reactor by the combination of electric conductivity of carbon membranes and electro-catalytic technology is built to treat dyeing wastewater and demonstrated a good development prospect, which is a promising electro-catalytic membrane material.In this paper, the coal-based flat microfiltration carbon membrane used for electro-catalytic membrane was prepared by the procedure of semi-dry pressing, drying and carbonization using blended coal, wetting agent, binder and pore-forming agent as raw materials. Effects of the ratio of coking coal and lean coal, wetting agent, binder and pore-forming agent, briquetting pressure and drying condition on the pore structure performance of the coal-based carbon membrane were investigated. Morphology and pore structure characteristics of carbon membrane were characterized by FT-IR, SEM, XRD and bubble-pressure methods. The results show that, the pore structure, mechanical strength and electrical conductivity of the coal-based carbon membrane can be optimized, and the optimum operation conditions are40%-60%coking coal of the total coal weight,15%wetting agent,10%binder,15%pore forming agent,20MPa briquetting pressure,10min holding time and7h drying time.To further improve the electrical conductivity and mechanical properties of coal-based carbon membrane, conductive materials (graphite, carbon black) and carbon fiber were added in the preparation of carbon membrane. The result shows that the conductive material can improve the conductivity of carbon membrane, but also reduces the mechanical strength of carbon membrane. Between them, graphite is more effective to enhance the conductivity of carbon membrane than carbon black, and5%-10%graphite is recommended.10%-15%short carbon fiber is favorable to reduce the brittleness of carbon membrane effectively, and improve the compressive strength of carbon membrane.TiO2as the electrocatalyst was coated onto the membrane to prepare a TiO2/carbon membrane to treat Acid Orange Ⅱ solution in the electro-catalytic membrane reactor in this paper. The result shows that TiO2electro-catalytic membrane reactor can significantly reduce membrane fouling, and the membrane flux decreases by only4%after12h. The recommended operating parameters are65ppm Acid Orange II solution,22g/L Na2SO4,500μL/min pump speed.