Fabrication Of Functional Nanocomposites For The Remediation Of Heavy Metals Pollution

With the progress of science and technology,the degree of social industrialization and urbanization has been increasing.Heavy metal pollution in industrial production is becoming more and more serious,which seriously threatens the sustainable development of ecological environment and causes problems to human health.How to effectively restore heavy metal pollution in the environment has become a hot and difficult research topic.Domestic and foreign researchers have conducted a lot of studies,put forward many methods and obtained many research results.Nano-adsorbent materials have made great progress in the treatment of heavy metal pollution due to their structure,large specific surface area,high porosity,easy functionalization,convenient application and large number of adsorption sites.The main work of this paper is to synthesize a variety of nano-composite materials to efficiently remove heavy metal ions in water and soil,and to study the removal mechanism,to provide scientific basis for heavy metal remediation,which is of great significance to the sustainable development of ecological environment and human health.The main contens are as follows:(1)In this study,a magnetic nanocomposite(denoted as FZ)was fabricated using Fe3O4 and zeolitic imidazolate framework-8(ZIF-8),based on a coprecipitation method.FZ could efficiently remove Cu2+(Cu(Ⅱ))and AsO2(As(Ⅲ))ions simultaneously from water,soil,and swine urine samples through hydrogen bonding and electrostatic interactions.The Cu(Ⅱ)and As(Ⅲ)removal efficiencies of the optimal FZ sample increased gradually with time and reached 99.1%and 98.4%(C0 of Cu(Ⅱ)and As(Ⅲ)was 10 mg/L,each),respectively,in 180 min.Additionally,the FZ with a high saturation magnetization(49.8 emu/g)was easily recovered from aqueous solutions and soil samples.Remarkably,the efficiencies of FZ in the removal of Cu(Ⅱ)and As(Ⅲ)were not affected by the presence of other coexisting ions.The adsorption isotherms,kinetics,and thermodynamics of FZ in the adsorption of Cu(Ⅱ)and As(Ⅲ)were also analyzed.Furthermore,zebrafish experiments indicated that FZ possessed a high biosafety.Thus,this study introduces a promising method for treating water,soil,and swine urine samples contaminated with Cu(Ⅱ)and As(Ⅲ),and verifies that FZ is suitable for practical application.(2)Herein,a novel magnetic iron-based carbon microsphere was prepared through co-hydrothermal treatment of tobacco waste liquid(TWL)and waste iron residue(WIR)to form WIR@TWL.After that,WIR@TWL was coated by sodium polyacrylate(SP)to fabricate WIR@TWL@SP whose removal efficiency for bivalent cadmium(Cd(Ⅱ))was studied in water and soil.WIR@TWL@SP possessed a high Cd(Ⅱ)removal efficiency,which could reach 98.5%within 2 h(C0 of Cd(Ⅱ)was 10 mg/L).Additionally,the removal mechanisms for Cd(Ⅱ)include cation-exchange,electrostatic attraction,hydrogen-bond interaction,and cation-πinteraction.Notably,pot experiments proved that WIR@TWL@SP can effectively reduce the absorption of Cd by plants in water and soil.Thus,this study offers a effective way for the remediation of Cd(Ⅱ)-contaminated water and soil,and may have a practical application value.(3)Tobacco waste liquid(TWL)is generally taken as a kind of highconcentration waste water with difficult treating process.In this work,OACT particle was fabricated by CaO,attapulgite(ATP),and TWL,and then OACT was coated by amino silicon oil(ASO)to form OACT@ASO particle.Therein,OACT@ASO had high controlled-release ability for fulvic acid(FA),because of nanonetworks structure for ATP and high content FA in TWL.The release ratio(RR)of FA from OACT@ASO reached 94%at 75 h in deionized water and 23%at 32 d in silica sand,respectively.Furthermore,the release mechanism of FA from OACT@ASO was consist with the First-order law.Additionally,OACT@ASO also possessed high immobilization capacity for Cu(Ⅱ),Cd(Ⅱ),and Pb(Ⅱ)in soil.Notably,pot experiment indicated that OACT@ASO could facilitate the growth of pakchoi seedlings and decrease the absorption of Cu(Ⅱ),Cd(Ⅱ),and Pb(Ⅱ)by pakchoi seedlings.Thus,this study provides a new kind of organic fertilizer particle which could not only release FA,but also immobilize Cu(Ⅱ),Cd(Ⅱ),and Pb(Ⅱ)in soil.(4)Soil acidification has negative effects on the sustainability of agricultural systems.In this present work,an acid soil amendment termed ASR was prepared with a nanocomposite consist of attapulgite(ATP),shell powder(SP),and red mud(RM),wherein ATP served as a nanocarrier.ASR could self-assembly to form a nanonetwork film around crop roots and hinder the input of H+and bivalent cadmium(Cd(Ⅱ))and the output of base cations(Ca2+ and Mg2+ and so on).Thus,ASR could effectively improve the pH of acid soil and meanwhile control the migration and spatial distribution of Cd(II),which reduced the bioavailable Cd(II)amount in the soil around crop roots.Note that pot experiment also indicated that ASR showed a positive effect on the growth of edible amaranths and significantly inhibited the uptake of Cd.