Removal of some heavy metals from waste water with natural materials as adsorbent

One of the most important environmental problems is the pollution caused by heavy metals in wastewaters. In this study, the removal of Zn+2, Cd+2, and Pb+2 ions from synthetically prepared solution was investigated with using coconut shell, olive stone, walnut shell, and their carbonized products as adsorbent. For this purpose, the effect of adsorbent type, contact time, adsorbent dose, and initial metal ion concentration were selected as independent variables while the heavy metal removal percentages, namely Zn+2, Cd+2, and Pb+2 removals, were selected as dependent variables in the heavy metal adsorption experiments. The microstructure properties of the tested adsorbents were examined using a Scanning Electron Microscope (SEM). It was found that carbonized products had more porous structure than their untreated forms. In adsorption experiments, temperature was kept constant 25 ±2 °C and pH was kept between 5.0 and 6.0. Adsorption experiments were carried out applying the batch system. Concentrations of heavy metals in synthetically prepared solution were determined by using Atomic Absorption Spectrometer analyzing technic. As a result of the experimental studies, the maximum contact time was determined as 180 min, the maximum adsorbent dose was determined as 2% adsorbent amount (g)/solution volume (mL), and the maximum metal removal was provided at lower initial ion concentration (50 ppm). It was observed that the removal percentage of heavy metal performances of carbonized products was found to be better than their untreated forms. Among the tested adsorbents, it was determined that the best adsorbent was the olive stone carbonized product for the adsorption of Zn+2, Cd+2, and Pb+2 ions because it had the more porous structure. Keywords: heavy metal, wastewater, adsorption, adsorbent, coconut shell, olive stone, walnut shell