Removal Of Typical Heavy Metal By Amino Biochar Modified By Nano Zero Valent Iron

Heavy metal pollution in environment was more and more serious with the rapidly social and economic development.Heavy metals posed a serious threat to human health because of the high toxicity,non-biodegradation and bioaccumulation,so its pollution control has been widely focused by many governments and scholars around the world.The adsorptive removal of heavy metals through cheap or environmentally friendly materials was a treatment with a good prospect.Biochar prepared by agricultural wastes was used to improve environment and soil pollution because of the present situation that a large number of agricultural wastes were urgent to utilize in the way of recycling,which was one of the research hotspots in the field of environmental remediation and agriculture.So agricultural wastes(palm)were used as raw materials for preparing an amino biochar modified by nano zero valent iron(NBCF).The removal performance of typical heavy metal ions by NBCF was investigated,and cadmium was selected as representative of heavy metals to do further research.Several main conclusions were as follows:1.An amino biochar modified by nano zero valent iron(NBCF)was prepared by electrophilic aromatic substitution and liquid reduction reactions.The removal performance of Cd(?),Cu(?),Ni(?)and Cr(VI)by NBCF was better than some of other same type adsorbent,and the adsorption capacity was 12.4,7.87,8.89 and 20.1 mg/g,respectively.2.From the characterization results,biochar was an irregular structure,amino moiety was successfully linked on the surface of biochar and the presence of considerable number of Fe0 made NBCF possess reduction activity.Nano zero valent iron particles were loose state and uniformly distributed on the surface of NBCF.The specific surface area of NBCF was 244 m2/g,and average pore diameter was 5.06 nm.Additionally,average particle size was 845 nm when NBCF was stably suspended in an aqueous solution.3.The results of adsorption kinetic experiments revealed that adsorption could be achieved equilibrium within 457 min and the data could be fitted with pseudo-second-order model.Intraparticle diffusion model showed that the adsorption rate was controlled by at least two steps.The adsorption/desorption isotherms of Cd(?)on NBCF was obviously nonlinear,meaning that it was chemisorption in addition to physical adsorption.It also could be observed the significant desorption hysteresis.The adsorption could be affected by environmental factors.Adsorption capacity was enhanced with solutions pH increase,and weakened with solution ionic strength increase,which might be related to the compressed electric double layer of loaded particles.4.The removal mechanism of heavy metal ions by NBCF might invole electrostatic interaction,complexation,precipitation and reduction.The modified biochar prepared in this study not only could be used for the treatment of heavy metal in wastewater but also for the improvement and passivation of heavy metal contaminated soil.At the same time,the utilization of agricultural waste could be achieved in the way of recycling when carrying out environmental remediation,which was a good prospect.