Nitrogen and sulfur co-doped biochar(NSBC)was synthesized from high temperature pyrolysis of carbon precursor,which was prepared by hydrothermal method using aloe bark as raw material and(NH4)2SO4 as nitrogen and sulfur sources,and then characterized by SEM,BET,XPS and Zeta potential.The adsorption performance of NSBC prepared by pyrolysis at different temperatures for Ni2+and Co2+in aqueous solution were evaluated,with the thermodynamic and kinetic processes explored.The influence of temperature and pH on their adsorption properties were analyzed,and the adsorption mechanism was speculated.The results showed that NSBC exhibited a lamellar and stacked porous surface structure.NSBC800 synthesized at 800 ℃ displayed a hierarchical porous structure,with a non-microporous proportion of 46％,a micropore volume of 0.07 cm3/g,and a specific surface area of 149 m2/g,while the surface contained 29.94％(molar fraction)oxygen,4.79％nitrogen,and 6.21％sulfur.The maximum equilibrium adsorption capacities of NSBC800 for Ni2+and Co2+were 245.70 and 223.71 mg/g,respectively.The chemical functional groups consisting of oxygen,nitrogen,and sulfur elements on the surface of NSBC800 underwent significant changes after adsorbing Ni2+and Co2+,which were able to react with metal ions to form salts or complexes,depositing on the biochar surface.The adsorption process of NSBC for Ni2+and Co2+was best described by the Langmuir model and pseudo-second-order kinetic model,indicating that the adsorption process was chemisorption-controlled.Multiple mechanisms including chelation,co-precipitation,ion exchange,and electrostatic attraction were identified in synergy in the removal of Ni2+and Co2+from the waste solution.
关键词
氮硫共掺杂/芦荟皮/生物质/废弃电池/Ni2+/Co2+/水处理技术
Key words
N,S-co doping/aloe vera rind/biomass/waste battery/Ni2+/Co2+/water treatment technology
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