Removal and Recovery of Lead from Aqueous Solution by Low Cost Media

Problem statement: To remove Pb(II) from wastewater using local UAE sand and then to recover the removed Pb(II). Approach: Removal efficiency of Pb(II) from wastewater was investigated using white, yellow and red United Arab Emirates sand with pore sizes < 300 μm. Two methods were employed: batch equilibrium and column filtration. In the batch equilibrium study, the effect of sand type and dosage on Pb(II) removal efficiency was investigated. In the column filtration study, removal efficiencies were measured using yellow sand at 0.100 dm³ intervals while continuously injecting 300 ppm Pb(II) solution into the column. Pb(II) concentrations were determined using inductively coupled plasma- atomic emission spectrometer (ICP-AES). Measurements were carried out until saturation of the column by Pb(II) was attained. Recovery efficiency of Pb(II) was initially investigated using distilled water, 0.100 mol dm⁻³ HNO₃ and pH 8.0 aqueous solutions. Recovery via chelation with Ethylenediaminetetraacetic Acid (EDTA) was then attempted. Results: Batch experiments showed that yellow sand was more efficient than either white or red sand in removing Pb(II), with a maximum removal capacity of 0.030 kg Pb(II) per kg yellow sand. Accordingly, yellow sand was selected for column filtration experiments. In column filtration, the removal capacity rose to a maximum of 0.086 kg Pb(II) per kg sand. When sand containing removed Pb(II) in batch experiments was equilibrated overnight with EDTA solutions in stoichiometric excess, 86.6% recovery was observed. By comparison, recovery using EDTA in column filtration was 94.7%. Recovery by injection of either water or 0.100 mol dm⁻³ HNO₃ solution was either negligible or much lower than that obtained with EDTA. Conclusion: Column filtration using UAE yellow sand is an efficient and inexpensive method to remove Pb(II) from wastewaters. Pb(II) can be efficiently recovered from yellow sand columns by chelation with EDTA.