Study On Nano TiO₂in Determination Of Heavy Metal Ions And Application Of Its Solid Waste In Photocatalytic Degradation Of Organic Pollutants

Water pollution is increasing seriously with the development of industry, particularly forpollutions caused by heavy metals and organics. It is an urgent problem to control the pollutionseffectively. As functional material with excellent properties, titanium dioxide has been widely paidattention.Inthispaper,titaniumdioxidewasmodifiedassolidphaseextractantfortheseparationandenrichment of heavy metal ions. Then, the material was reused as photocatalyst to achieve thepurpose of solid waste reuse. In addition, magnetic catalyst with core-shell structure was preparedaiming at the problem that titanium dioxide is difficult to separate from the catalytic system. Themainresearchworksareasfollowing:(1) Titanium dioxide nanoparticles were prepared using an available and low prices rawmaterialtetrabutyl titanate (TBOT). Then titanium dioxide particles were modified by dithizone (DZ)and humic acid sodium(NaHc) to prepareTiO2-DZ and TiO2-NaHc, respectively. The structures ofthe materials were characterized by XRD and FTIR. The materials were applied to separate andenrich trace heavy metal ions in water samples. Effects of adsorbent amount, pH of water sample,adsorption time, eluant component, elution time and other factors on recovery of heavy metal ionswere investigated. Under the optimal conditions, the water samples were analyzed and the resultsshowedthattheadsorbentexhibitedgoodstabilityandhighadsorptionperformance.(2)After being used asadsorbent forheavymetalions, TiO2-NaHcwererecycled and calcined.The materialsobtianed wereusedasphotocatalyststo degradatedifferent kindsoforganicpollutantssuch as dye, organophosphorus pesticide, carbamates pesticide and bactericide. The resultsdemonstratedthatthephotodegradationperformaneofthesephotocatalystsissatifactory.(3) Using FeCl3·6H2Oasrawmaterial, super paramagnetic Fe3O4corewas prepared by meansof hydrothermal reaction. Then SiO2and TiO2were coated using a sol-gel process andTiO2@SiO2@Fe3O4nanocompositeswithmagneticcore-shellstructuresweresuccessfullyobtained.X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were used for thecharacterization of the synthesized products. The results showed that SiO2@Fe3O4was well coatedby the nona TiO2to form a core-shell structure. The magnetic particals were found to have good photocatalytic performance for Rhodamine B (RhB) and imazalil aqueous solutions. The magneticcore coated by SiO2and TiO2layer could be easily separated from the solution after thephotocatalyticprocess.