Synthesis Of Nanocomposites And Their Perpormances On The Removal Of Heavy Metal Ions And Organic Pollutant

The environmental pollution is becoming more seriously, especially for the waterpollution. Heavy metal ions and organic pollutant have become the most seriouscontributors to water pollution. In this paper, nanostructured BiOBr microspheres weresynthesized with the method of hydrothermal and be used to adsorb the heavy metalions and purify the drinking water with low concentration of heavy metal ions.Double heterostructure SnO2@SnS2/TiO2and two-dimensional heterostructureTiO2@g-C3N4composites were prepared with the theory of heterostructure design andconstruction. Their degradation activities to MO under both ultraviolet and visible lightirradiation were investigated. ZnO nanoparticles were fixed to the surface of carbonfibers with the help of hydrolysis of zinc chloride under alkaline conditions. Thecarbon fibers were then mixed with the plant fibers to manufacture a photocatalyticpaper that was applied to the degradation of MO under UV light irradiation. In thepaper, the synthesized samples were characterized by SEM, TEM, XRD, FTIR, EDSMapping, DRS, AFM and PL spectrum. It is found that the as-synthesizednanostructured BiOBr microspheres with higher feeding ratio of Br to Bi are composedof nano-platelets with larger size and possess larger diameter and specific surface area.The nanostructured BiOBr microspheres show good and efficient adsorption capacityfor heavy metal ions such as Cr(VI), Cd(II) and Pb(II), which is due to the largespecific surface area of the BiOBr and the chemical bonding between heavy metal ionsand BiOBr. Based on the quick and efficient heavy metal ion removal ability, acontinuous filtering-type water purification device was designed and constructed. Itshows excellent adsorption properties for low concentration heavy metal ions. Theremoval capacities to Pb (II), Cd (II) and Cr (VI) are4.9kg/g,5.7kg/g and21.5kg/g,respectively.The double heterostuctured SnO2@SnS2/TiO2composite, which was synthesizedwith the liquid precipitation method, exhibits good degradation effect on MO underultraviolet or visible light irradiation. The degradation rate of MO is as high as95%after2h of visible light irradiation, and98%after30min of UV-light irradiation,which are higher than that of TiO2nanobelts. The improvement is attributed to theformation of heterostructure and the energy band matching.The two-dimensional heterostructured TiO2@g-C3N4composite, which wasprepared by gradually removal of liquid medium via evaporation and self-assembly, shows a core-shell structure, in which the g-C3N4sheet was tightly attached to thesurface of TiO2nanobelts. By means of the analysis of energy band matching and PLspectrum, the photo-induced carriers were effectively separated and extremelyimproved the photocatalytic activities to the MO degradation.ZnO nanoparticles-based photocatalytic paper, which are composed of ZnOloaded carbon fibers and cellulose fibers, has a rather good photocatalytic performanceon degrading organic pollutant MO when the mass ratio of carbon fiber to cellulosefiber is1:1and the loaded amount of ZnO nanoparticles in paper is0.058mmol/g. Thepaper loaded with ZnO nanoparticles prepared by hydrolysis of zinc chloride showsbetter performance on degrading MO than that loaded with commercial ZnOnanoparticles. The photocatalytic paper still shows a good degradation effect on MOeven after being repeatedly used for three times.