Removal of lead in a fixed-bed column packed with activated carbon and crab shell

Crab shell particles (Protunus trituberculatus) and activated carbon (Norit 0,8 SUPRA) were used as packing materials in a fixed-bed column. When 1 g crab shell was added in a column packed with 10 g activated carbon, breakthrough occurred at 1500 bed volumes as compared to 380 bed volumes for 10 g activated carbon only. The addition of crab shell particles into an activated carbon column resulted in an increased uptake of lead. The dramatic improvement might be attributed to an increase in CO32- and OH- available for binding lead. From the results of SEM, XRD, and FT-IR analyses, the major mechanism of lead removal was based on dissolution of CaCO3 in the crab shell followed by precipitation of Pb-3(CO3)(2)(OH)(2(s)) on the surface of activated carbon. The lead uptake increased twofold when the influent lead concentration was increased from 10 to 50 mg/L.