Due to non-biodegradability and food chain biomagnification, Pb(II) shows severe toxicity even at trace levels. However, high capacity and selective removal of Pb(II) remains a challenge. Here, calcium oxalate was modified by maltose (Ma-COM) and used to adsorb Pb(II) from wastewaters. The morphology, crystal structure, thermal stability and other physicochemical properties of Ma-COM were investigated by SEM, XRD, TGA, FTIR, TEM, Zeta potential and N 2 isotherm measurements. The effects of temperature, Pb(II) concentration, contact time, pH value and coexisting ions on Ma-COM adsorption properties were systematically studied and optimized. It was found that Ma-COM showed Pb(II) adsorption capacity up to 1941.6 mg/g. The lead removal rate of lead wastewater with concentration less than 250 mg/L could reach 92% after 60 min treatment. The adsorption mechanism was proposed to be the synergistic effect of surface ion exchange, complexation and electrostatic interaction. Furthermore, The coexistence of divalent cations had negligible effect on Pb(II) adsorption. The material showed high selective Pb(II) adsorption. Importantly, Ma-COM exhibited excellent adsorption performance on Pb(II) in various actual water samples, such as dye wastewater, domestic sewage, sewage effluents and river water, and the treated water samples can be safely discharged. Therefore, as an environmental green, economical, easily available and efficient adsorbent, Ma-COM adsorbent showed great potential for the treatment of lead containing wastewater
