Effect Of Sludge Biochar Loaded With Nano Zero-valent Iron On Antimony Mobility In Water And Soil Ji,Jianghao

As rapid industrial and social growth,antimony mines are the overexploited,leading to the accumulation of antimony in the aquatic and terrestrial environment near mines,which harm human health.To eradicate antimony from water near mine and ensure soil near mine to be reutilized safely,this research utilized an innovative carbonaceous nanomaterial that is sludge biochar loaded with zero-valent iron to remediate antimony mine through two systems,which are aqueous phase and indoor soil incubation.Investigation of the adsorption mechanism uses X-ray photoelectron spectroscopy to analyze variation of antimony before and after adsorption.Remediation effect on antimony in soil near mine is discussed through detecting soil properties and content of antimony fraction.The main conclusions are as folloews:（1）Characterization of carbonaceous material using EDS,FTIR and XRD showed that content of iron increased from 4.18%to 17.76%,and crystal phase of iron（031）was found.Therefore,it was concluded that iron had been supported successfully on the surface of BC.Additionally,it is observed using SEM and BET that specific surface area of nZVI-BC increased from12.1 m²·g^-1to 38.93 m²·g^-1,and the porous structure has been improved so that more Fe⁰ on the surface of BC becomes adsorption site.In theory,therefore,nZVI-BC has superior ability to remove contaminants.（2）The maxmium adsorption capacity of BC and nZVI-BC are 15.53 mg·g^-1 and 45.06 mg·g^-1,respectively.And the adsorption process occurred through the synergistic effects of monolayer and multilayer adsorption.The adsorption process of BC is exothermic,whereas the adsorption process of nZVI-BC is endothermic.The adsorption equilibrium reached within 60 min,which indicated nZVI-BC has a faster adsorption rate for antimony.Additionally,nZVI-BC still has a greater removal rate for antimony under influence of other coexistent ions.The removal rate for antimony remained approximately 80%after three cycles and reuse four times.（3）Trivalent antimony is oxided into pentavalent antimony by·O.And pentavalent antimony combined with·OH/·O to form oxygen anion（Sb O₃^-/Sb（OH）₆^-）,which further is adsorbed on the surface of nZVI-BC through electrostatic attraction with Fe（Ⅲ）-O.（4）After adding nZVI-BC into soil,the cation exchange capacity（CEC）in soil decreased and the soil catalase（S-CAT）activity improved.The decreased CEC is because that BC provided active site that fixes other cation in soil on the surface of nZVI-BC in convenience to combine with antimony in the form of anion,eventually,which formed stable compounds.Additionally,enhanced S-CAT can weaken toxicity effecr of nZVI-BC on plants.In conclusion,it is deduced that the behavior that BC supported nZVI can weaken toxicity effect of nZVI on plants.（5）The stability of antimony in the soil was enhanced after adding nZVI–BC.And percentage of exchangeable antimony is decreased,while the percentage of fraction of bound to iron and manganese oxides is increased,which stated that nZVI-BC facilitated stabilization of antimony.After cultivating potted plants 56 d with nZVI-BC,the percentage of exchangeable antimony decreased from 15%to 2%.Additionally,BC promote plant growth.Moreover,BCF of Lolium perenne L.and Galinsoga parviflora Cav.decreaed from 0.46 and 0.26 to 0.21 and 0.17,respectively,which stated that BC decreased bioavailability of antimony in soil,reduded BCF of plant for antimony and mitigated the risk of antimony harm to human.