The use of natural zeolite to remove heavy metals Cu (II), Pb (II) and Cd (II), from industrial wastewater

In this study, the adsorption behavior of Cu2+, Pb2+ and Cd2+ from synthetic metal solutions using natural zeolites was studied in order to investigate the efficiency of adsorbents of heavy metals from industrial wastewater. The kinetic study indicated the suitability of the zeolite for the removal of Cu2+, Pb2+ and Cd2+ ions from synthetic wastewater; batch experiments were used to identify the effect of parameters that affect the rate of adsorption such as the adsorbent mass, the initial solution concentration, the initial solution pH, the adsorbent particle size, and the agitation speed and evaluated their impact on the removal efficiency of heavy metals from industrial wastewater using the natural zeolite. Zeolite samples with masses between 1 g and 10 g were contacted with constant volume (100 ml) of multicomponent synthetic solutions containing Cu2+, Pb2+ and Cd2+ ions. They were agitated at agitation speeds in the range of 100-300 rpm for agitation times from 1 hr to 8 hrs in a magnetic stirrer at room temperature, the pH values were monitored and adjusted regularly. Every hour, 15 ml of the samples was analyzed using the Atomic Absorption Spectroscopy. The results show that the removal efficiency of Cu-2(+) increase from 60% for 1 gr to 99% for 10 gr of the mass of absorbent, increase from 62% for 1% to 94% for 7 of the initial solution pH, increase from 90% for 100 rpm to 94% for 300 rpm of the agitation speed, the amount adsorbed increase from 0.5 mg/g for 100 mg/l to 2.1% for 400 mg/l of the initial solution concentration. Similar results are obtained for the two other heavy metals (Pb2+, Cd2+) and showed that the capacity of the adsorbents for the removal of heavy metals is directly proportional to the mass of absorbent, initial solution pH, agitation speed, and initial solution concentration. The highest adsorption rate of Cu2+, Pb2+ and Cd2+ ions took place in the first hours followed by a slower adsorption rate later on.