Preparation Of Semi-coke-based Activated Carbon And Application In Cyanide-containing Wastewater

Activated carbon was prepared with the semi-coke as raw material and KOH as activator. It was applied in the integrated treatment of cyanide-containing wastewater, which opened up a new way for the comprehensive utilization of the cyanide waste water.The preparation experiment of Semi-coke-based activated carbon focuses on the influences of alkali mixed way, granularity, alkali carbon ratio, activation temperature and constant temperature time on the yield, the iodine adsorption value of activated carbon. Semi-coke-based activated carbon was characterized by SEM, XRD, FT – IR. The results showed that with the decrease of raw material particle size, the yield decreasing, iodine adsorption continuously improve. Alkali carbon ratios ranging from 0.25:1 to 1.5:1, the greater the alkali carbon ratio, the lower the yield, the greater the iodine adsorption. With the increase of activation temperature and the prolong of activation time, the yield decreasing, iodine adsorption was first increases and then decreases.When the grain size was 0.6mm to 0.3mm(28~48eyes), alkali carbon ratio was 1.5:1, the activation temperature was 800℃, constant temperature time was 2h, the actived carbon yield, the iodine adsorption value was 66.7%, 803.277mg·g-1 separately. This was the best process conditions and result. The surface of activated carbon containing a large amount of carboxyl, hydroxyl, carbonyl and other functional groups.Application experiments of the semi-coke based activated carbon in cyanide-containing wastewater focused on the effects of the dosing quantity, adsorption time, adsorption temperature and pH. Results showed that the semi-coke-based activated carbon used in the treatment of cyanide-containing wastewater is feasible.The removal rate of each ion was increase, with the increase of dosage of activated carbon, with the decrease of adsorption temperature, with the increase of adsorption time, with thedecrease of pH. When dosing quantity of activated carbon was 5g/100 ml, adsorption time was 2h, adsorption temperature was room temperature, the removal rate of Cu ions, Zn ions, CN-, total cyanide can reach 100%, 93.51%, 71.52%, 90.96% separately. Kinetics study of Zn ions showed that the adsorption behavior conformed to the second-order kinetic model and adsorption capacity was 353.357mg·g-1. Rate constant k was 5.6×10-3 which suggested that the adsorption rate was very soon. Thermodynamics research showed that the zinc ion adsorption behavior conformed to Freundlich isothermal model. The index n>1 which showed that there was a strong affinity between zinc ion and activated carbon strong affinity. The adsorption thermodynamic parameters ΔG0<0, ΔH0<0, ΔS0<0 indicated that the adsorption process from a disordered state to an ordered state was spontaneous and exothermic.