The Research Of The Preparation Of Activated Carbon From Walnut Shell By CO₂ Fluidization And Its Adsorption Characteristics For Cu²⁺ Ion

Heavy metal waste water pollution has caused great harm on human society. There are many ways to deal with heavy metals wastewater, amongst which activated carbon adsorption is effective due to its stability and recyclability. In order to prepare suitable activated carbon which has strong adsorption and low cost, walnut shell was used as carbonized material to prepare activated carbon in a fluidized state, using activated carbon to removal of copper ion from aqueous solution.Activated carbon from walnut shell by CO2 fluidization, was prepared and characterized by a specific surface area analyzer on its surface pore structure. The effects of the particle size and activation time for pore structure were studied. The smaller particle size of walnut shell could get the larger surface area and pore volume that was prepared under the same conditions, but the char yield is reduced from 18% to 6%. Activated carbon surface area and pore volume increased with increasing activation time and then decreased with further increasing. The largest surface area and pore volume were 781m2/g and 0.300cm3/g respectively. MP and the BJH method were used to analyze the micropore structure and mesopore structure of activated carbon; the micropore size was focused on the size of 0.6nm, and there are a small number of mesopore which size was focused on the 2.4nm. Activated carbon was prepared from walnut shell has a amount of uniform miscropore structure.Activated carbon prepared from walnut shell was used to removal copper ion from aqueous solution. The effects of adsorption time and the initial concentration on the adsorption of copper ion were studied. Adsorption rate increased quickly after 10min when adsorption has began and reached adsorption dynamic equilibrium adsorption after two hours. When adsorption temperature is 30℃, the initial concentration of the solution is 30mg/L, pH 5.5, and activated carbon dosage is 0.3g/25mL, the removal rate can reach 99% and the adsorption capacity of Cu2+ is 1.82mg/g, and thus the removal of copper ion from wastewater can fit the discharge standards.