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

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 -43.1 mV, 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 599.4 mg/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.