Enhanced adsorption of Pb(II) by phosphorus-modified chicken manure and Chinese medicine residue co-pyrolysis biochar.

Abstract

The pollution of lead (Pb (II)) to water resources is becoming more and more serious. It is always a difficult problem to find efficient and low-cost adsorbents. Chicken manure (CM) and Chinese medicine residue (CMR) were modified with potassium dihydrogen phosphate (KH2 PO4 ) and pyrolyzed to obtain a modified material (PBC) for the treatment of Pb(II) in an aqueous solution. A variety of characterization analysis results could prove that KH2 PO4 was successfully introduced to PBC. By adjusting the initial pH, the zeta potential of PBC varies from -3.2 to -43.1mV, it could be seen that PBC had excellent applicability in the broad range pH value (1.0-6.0). Experimental and model results showed that R2 of the pseudo-first order kinetic model and the pseudo-second order kinetic model are greater than 0.99, indicating that that physical and chemical adsorption played a significant role in Pb(II) removal by PBC. An adsorption isotherm analysis showed that the adsorption capacity n in this study is greater than 1, confirming that PBC has a good adsorption effect on Pb (II). R2 of the Langmuir model of PBC is 0.981, and its maximum adsorption capacity of Pb(II) could reach 599.4mg/g. Environmentally friendly PBC could be used as an effective adsorbent to remove Pb(II) from aqueous systems. RESEARCH HIGHLIGHTS: Chicken manure and Chinese medicine residue were converted into biochar to improve utilization. The modified biochar exhibited extraordinary Pb(II) adsorption capacity. Adsorption mechanisms: Surface complexation, ions exchange, coprecipitation, and so on. Remained great Pb(II) removal efficiency at different pH and Pb(II) concentration.