Effective Removal Of As(Ⅴ) And Pb(Ⅱ) From Wastewater By P-S-Fe Modified Biochar Derived From Banana Peel

Arsenic(As)and Lead(Pb)pollution has drawn the attention of scholarly circles as a global environmental issue that requires immediate attention.Although environmental laws are growing more stronger,arsenic and lead pollution control has progressively gained public attention.However,the current form of arsenic and lead pollution remains severe.Among various methods for removing As and Pb,adsorption has been regarded as the most promising due to several appealing characteristics such as easy process,high efficiency,and low cost.However,the high production costs of current common adsorbents such as activated carbon,alumina,and silica have hindered the widespread use of adsorption,and there is an urgent need for the development of cost-effective adsorbents as well as the selection of an efficient carbonization and modification approach for biochar production.Hydrothermal synthesis or carbonization is characterized by a thermochemical process that involves submerging biomass in water and sealed in a confined heated system,which can provide an effective and potential alternative for biochar production.Hydrothermal synthesis using banana peel as raw material enhanced by phosphate,sulfur,and iron(P-S-Fe)produce not only functional biochar for effective As and Pb removal,but also reduces high energy consumption,which has great potential for energy saving.The combine use of P-S-Fe in modifying the biochar surface increases the number of existing functional groups,introduce new functional groups,and form strong complexes with metal ions.In this paper,we proposed the idea of hydrothermal synthesis for the production of dehydrated banana peel biochar modified by(P-S-Fe)with excellent attraction for effectively removing As(Ⅴ)and Pb(Ⅱ)ions from wastewater.We prepare and modify low-cost dehydrated banana peel biochar by Phosphate-sulfur-Iron(P-S-Fe)under 180℃ and 1200℃,and evaluate the adsorption characteristics of As(Ⅴ)and Pb(Ⅱ)on P-S-Fe(biochar)and pristine banana peel biochar(PBPB),and evaluate the different influencing parameters:pH,time,dosage,and also evaluate the kinetic and isotherm models,and lastly analyzed the adsorption mechanisms of As(Ⅴ)and Pb(Ⅱ)on P-S-Fe-biochar using FTIR,XRD,XPS.The specific conclusion are as follows:1.We have prepared the materials by the hydrothermal synthesis method:PBPB,phosphate-iron(P-Fe)modified,sulfur-iron(S-Fe)modified and Phosphate-sulfur-Iron(P-S-Fe)modified banana peel biochar.After the experimental control treatment analysis,it was found that 0.25g P-S-Fe modified banana peel biochar had the highest adsorption efficiencies for As(Ⅴ)and Pb(Ⅱ),and they were 98.7%and 90.3%,respectively.In addition,the order of the adsorption rate for As(Ⅴ)is P-S-Fe-biochar>S-Fe-biochar>PBPB>P-Fe-biochar,and that for Pb(Ⅱ)is P-S-Fe-biochar>P-Febiochar>PBPB>S-Fe-biochar,respectively.At pH=7,the maximum removal rate of As(Ⅴ)and Pb(Ⅱ)was 99.4%and 93.9%for P-S-Fe-biochar,and the high adsorption rate of 98.7%and 90.3%for As(Ⅴ)and Pb(Ⅱ)in time effect analysis was achieved in 24 h for P-S-Fe-biochar.For dosage analysis,1g dose of P-S-Fe-biochar achieved a higher removal efficiency of 96%and 93.7%for As(Ⅴ)and Pb(Ⅱ).2.Freundlich and Langmuir’s isotherms fitted the adsorption data,with Langmuir achieving the maximum capacities of 39.5,33.2,26.4 and 23.5 mg g-1 for P-S-Fe-biochar loaded As(Ⅴ),P-S-Fe-biochar loaded Pb(Ⅱ),PBPB loaded Pb(Ⅱ)and PBPB loaded As(Ⅴ),respectively.Pseudo-secondorder fitted the adsorption data achieving a high R2 value after experimental calculation.After adsorption for SEM,the P-S-Fe-biochar surface becomes smooth and shiny with closed pore walls,and the EDS image revealed an even dispersion of P,S,Fe,Ca,and O components on the P-S-Fe-biochar surface,suggesting a successful modification,with As(V)and Pb(Ⅱ)ions showing after adsorption.Minerals such as(Arsenic trisulfide)AS2S3,(Lead sulfide)PbSO4,and(Disodium hydrogen arsenate)Na2HASO4 were seen on both XRD and XPS,suggesting that both metal ions were successfully adsorbed.P-S-Fe-biochar total pore volume(Vtot)was approximately 2.67 times that of PBPB,achieving the BET surface of(18.2 and 15.7 m2g-1)for PBPB and P-S-Fe-biochar,respectively.P-S-Fe-biochar was selected for mechanism analysis,and characterization from XRD,FTIR,and XPS proposed four distinct adsorption processes for As(Ⅴ)and Pb(Ⅱ):ion exchange,precipitation with minerals electrostatic attraction,and surface complexation.Our research will provide a feasible method to use low-cost P-S-Fe modified banana peel biochar to treat wastewater contaminated by As(Ⅴ)and Pb(Ⅱ).25 Figures,14 Tables,and 317 References...