Study On Adsorption Properties And Mechanism Of Pb By Modified Areca Biochar

Pb（Ⅱ）has significant biotoxicity and seriously affects human health,becoming a hot topic in environmental concerns.In this study,solid waste betel nut（AN）was used as raw material,and nanoscale zinc ferrite and potassium permanganate were used for modification to obtain zinc ferrite modified betel nut（ZMBN）and activated betel nut biochar modified with potassium permanganate（ABMP）,respectively.ZMBN and ABMP were applied separately to remove Pb（Ⅱ）from simulated wastewater,and their removal mechanisms were investigated.The main research results are as follows:（1）Under the same temperature conditions,the adsorption capacity of ZMBN for Pb（Ⅱ）increases with the increase of the initial concentration of Pb（Ⅱ）.At 35℃,45℃,and 25℃,the maximum adsorption capacities are 59.66,52.68,and 23.60 mg/g,respectively.The pseudo-second-order kinetic and Freundlich isotherm models can better describe the adsorption process of ZMBN for Pb（Ⅱ）in water,indicating that the adsorption of Pb（Ⅱ）by ZMBN is mainly through multilayer chemical adsorption.Ca²⁺has a promoting effect on the removal of Pb（Ⅱ）from water by ZMBN.After four consecutive cycles of adsorption-desorption,the adsorption capacity of Pb（Ⅱ）by ZMBN can still be above 97.0%,demonstrating the good recycling ability and stability of ZMBN.The characterization analysis shows that the specific surface area and pore volume of modified ZMBN are increased,and Zn Fe₂O₄is successfully loaded on ZMBN,indicating that the modification method has a good effect on AN.After the adsorption of Pb（Ⅱ）by ZMBN,Pb CO₃,Pb-O-Zn,Pb-O-Fe,C-O-Pb,C-Pb,and C-Pb are generated,indicating that ZMBN can undergo electrostatic interaction,ion exchange,precipitation,and surface complexation reactions with Pb（Ⅱ）.There is a coordination relationship between the adsorbed Pb（Ⅱ）and ZMBN.Therefore,ZMBN is an effective and low-cost adsorbent for treating Pb（Ⅱ）-contaminated wastewater.（2）The equilibrium time for the adsorption reaction is only 60 min.Under the same temperature,the adsorption capacity of ABMP for Pb（Ⅱ）increases with the increase of initial concentration.At 25°C,35°C,and 45°C,the maximum adsorption capacities are 50.8,56.0,and 61.0 mg/g,respectively.The adsorption process of Pb（Ⅱ）by ABMP in water solution is better described by the pseudo-second-order kinetics and Freundlich isotherm model,indicating that the adsorption of Pb（Ⅱ）by ABMP is mainly through multilayer chemical adsorption.Mg²⁺has a promoting effect on the removal of Pb（Ⅱ）from water by ABMP.After four consecutive adsorption-desorption cycles,the adsorption capacity of Pb（Ⅱ）by ABMP remains above 93.7%,indicating that ABMP has good recycling and stability.The characterization analysis shows that the modified ABMP has an increased specific surface area and pore volume,and manganese oxide is successfully loaded onto the surface of ABMP.The modification method has a good effect on AN.Pb O-is generated after Pb（Ⅱ）is adsorbed by ABMP,indicating that ABMP can undergo electrostatic interactions and surface complexation reactions with Pb（Ⅱ）.There is a coordination relationship between the adsorbed Pb（Ⅱ）and ABMP.Therefore,ABMP is an efficient and low-cost adsorbent for the treatment of Pb（Ⅱ）wastewater.