A study on the reduction of heavy metal ions (Cd2+ and Cr3+) in waste water from chemistry laboratory by Pericopsis elata adsorbent

Abstract

This research was aimed the at preparation and application of Pericopsis elata adsorbent in reducing the concentration of heavy metal ions present in waste water obtained from chemistry laboratory. Atomic Absorption Spectroscopy (AAS) was used to determine the concentration of heavy metal ions (Cd2+ and Cr3+) in laboratory waste water. The concentration of Cd and Cr were 155 and 122 mg/L. At a dosage of 0.25, 0.5 and 0.75 g the concentration ranged from 21.55 25.65 mg/L for Cr and 12.90 14.32 mg/L for Cd. At pH value of 2, 7 and 11, the concentration were 11.30, 20.33 and 39.50 mg/L for Cr and 15.30, 28.20 and 24.80 mg/L for Cd respectively. The concentration of Cr and Cd on adsorption increases with an increase in contact time of the adsorbate. At contact time of 20, 40 and 60, the adsorption concentration were 16.60, 19.30 and 29.40 (mg/L) for Cr and 10.50, 20.40, 48.10 (mg/L) for Cd. The results indicate that as the pH, contact time and temperature increases, the percentage removal of Cr and Cd also increases. As adsorbent dosage increased the percentage removal of Cr and Cd also increased. The result of the morphology showed a porous, rough and irregular surface with crystalline structure which indicated more macro pores for adsorption. It can be deduced that the Pericopsis elata adsorbent provides an external surface of porous and more reactive sites, which enhanced its adsorption capacity.