Synthesis Of Biomass Carbon Supported Nanoscale Zerovalent Iron Composites And The Application In Nickel Wastewater Treatment

Along with social economic development,the heavy metal pollution problems had become increasingly prominent.Research showed that nickel can lead to contact allergic dermatitis.For urban residents who suffered long term exposure of nickel contaminated water sources can cause respiratory cancer.Therefore,it is urgent to study the removal of heavy metal nickel in water.Nanoscale zerovalent iron(nZVI)has high reactivity,which leads to an strong reducibility of heavy metal nickel ion.However,due to the high reducibility led itself easily be oxidized and agglomeration and the decrease of reactivity.Biomass carbon(BC)has large surface area and high adsorbability and a favorable adsorption of nickel.Integrating large specific surface area and strong reactivity,nZVI/BC can remove nickel pollutants effectively.Currently n ZVI/BC is one of the most potential materials.This artical use biomass carbon supported nZVI composite to remove Ni2+ from water.The synthesized nZVI/BC composites were characterized by XRD,FT-IR,Raman and Nitrogen adsorption/desorption.The effects of the content of iron,solution temperature,pH value and initial concentration of nickel ion on the removal of nickel were investigated.The kinetics,adsorption isotherm and mechanism of Ni2+ removal were also discussed in this work.The main results were presented:(1)x Fe/g-C composites were prepared by hydrothermal carbonization and carbothermal reduction method useing glucose as basic raw material.Results found that optimized temperature for synthesis of xFe/g-C was higher than 800 ? under N2 atmosphere.Iron species existed in Fe,which promoted the redox reaction between iron and nickel.The results demonstrated that:mechanism analysis indicated that the Ni2+ uptake by the zero valent iron was mainly via a redox by ?-Fe particles.The higher of the dosages of iron and reaction pH could make the removal efficiency first increased and then increased.The rate of Ni2+ removal reduced with the higher of temperature.With the increasing of the initial concentration of Ni2+ the adsorption capacity decreased.Under the conditions of the reaction temperature 30 ? and the pH= 5,the extent of Ni2+(20 mg/L)by 18.4Fe/g-C material(iron content 18.4wt%)reached 86.8%.The kinetic data of adsorption reactions were described by pseudo-second-order equations.The adsorption model was best described by the Langmuir isotherm model.(2)xFe/C composites were prepared by direct carbonization and carbothermal reduction method useing flour as basic element and iron nitrate as the precursor.The results showed that the xFe/C material had mesoporous structure and amorphous and graphitic structure.Iron species mainly existed in the form of Fe,but because the activity is very strong,the part of iron is oxidized to ferric oxide.The rate of Ni2+ removal inreased with the higher of temperature.With the increasing of the initial concentration of Ni2+ the rate of Ni2+ removal decreased.Under the conditions of the reaction temperature30 ? and the pH = 5,the extent of Ni2+(100 mg/L)by 65.5Fe/C material reached 94.92%.The removal of nickel including two kinds of mechanism that was adsorption and reduction.The synergy between nZVI and foam carbon promoted the uptake of nickel.The removal results of Ni2+ by65.5Fe/C conform to pseudo-second-order reaction.Adsorption isotherm was matched with Langmuir model,and the adsorption is monolayer adsorption.