Preparation Of Semiconductor Nanomaterials And Studies On Their Toxicology Effects Arid Photoelectrochemical Catalytic Degradation Of Pollutants

Nowadays, there has been a rapid growth of research in the research of nanomaterialswhich can be used in a multitude of industrial and biomedical processes. Nanomaterials,which possess novel optical, electronic and chemical properties, have potential applications inbiotechnology and life sciences. In addition, semiconductor nanomaterials have attracted aconsiderable concern for the application in photoelectrochemical catalytic degradation oforganic pollutants. As a green chemistry technology, photocatalysis can decompose organicpollutants completely into harmless chemicals such as H₂O and CO₂. Therefore, numerousattempts have been made to study the reaction mechanism and develop novel and moreefficient semiconductor catalytic materials for pollution treatment. On the other hand, with thewidespread use of nanomaterials, more and more nanomaterials come into people’s lives atpresent. Numbers of studies have shown that some nanomaterials may have potentiallyharmful influence on human health, and can do harm to human health through various ways，such as breathing, skin contact, esophagus, and injection. Proteins are important materialfoundations of life activities and major component of living organisms. Various toxic andharmful substances come into human bodies can interact with these biologicalmacromolecules to show their harmfulness. Therefore, it is urgent to understand the detailedreaction pattern at functional macromolecular level and study the influence of nanoparticleson structure and function of biological macromolecules. It will provide us novel and morereliable evaluation methods of nanoparticles toxicity.In this paper, we have studied the interaction between the functional semiconductornanomaterials and the biological macromolecules and their applications in the field ofphotoelectrochemical catalytic degradation of pollutants, which could be divided into threeaspects as follows:（1） The interaction between flower-like CdSe nanostructure particles （CdSe NP） andbovine serum albumin （BSA） was investigated from a spectroscopic angle under simulativephysiological conditions. Under pH7.4, CdSe NP could effectively quench the intrinsicfluorescence of BSA via static quenching. The binding constant （KA） was6.38,3.27, and1.90×10⁴L/mol at298,304and310K, respectively and the number of binding sites was1.20.According to the Van’t Hoff equation, the thermodynamic parameters （ΔH=-77.48kJ mol-1,ΔS=-168.17J mol-1K-1） indicated that hydrogen bonds and van der Waals forces played amajor role in stabilizing the BSA-CdSe complex. Besides, UV-vis and circular dichroism （CD）results showed that the addition of CdSe NP changed the secondary structure of BSA and led to a decrease in α-helix. These results suggested that BSA underwent substantialconformational changes induced by flower-like CdSe nanostructure particles.（2） The interaction between cuprous oxide （Cu₂O） nanocubes and bovine serum albumin（BSA） was investigated from a spectroscopic angle under simulative physiological conditions.Under pH7.4, Cu₂O could effectively quench the intrinsic fluorescence of BSA via staticquenching. The apparent binding constant （KA） was3.23,1.91, and1.20×10⁴L/mol at298,304, and310K, respectively, and the number of binding sites was1.05. According to theVan’t Hoff equation, the thermodynamic parameters （ΔH=-63.39kJ mol-1, ΔS=-126.45J mol-1K-1） indicated that hydrogen bonds and van der Waals forces played a major role instabilizing the BSA-Cu₂O complex. Besides, the average binding distance （r0=2.76nm） andthe critical energy transfer distance （R₀=2.35nm） between Cu₂O and BSA were alsoevaluated according to F rster’s non-radioactive energy transfer theory. Furthermore,UV-visible and circular dichroism results showed that the addition of Cu₂O changed thesecondary structure of BSA and led to a decrease in α-helix. All results showed that BSAunderwent substantial conformational changes induced by Cu₂O, which can be very helpful inthe study of nanomaterials in the application of biomaterials.（3） The electrocatalytic method for the degradation of bisphenol A （BPA） in water wasbased on a novel Ti-based PbO₂-ionic liquids （ILs） electrode. The electrode showed a highstability and reusability due to the better electroconductivity and reusability of ILs. Besides,the influence factors on BPA degradation were investigated in detail, and under the optimalconditions the degradation efficiency of BPA could reach100%within150min. What’s more,over75%chemical oxygen demand （COD） removal was achieved on PbO₂-ILs （10%）/Tielectrode. The mechanism of the degradation reaction was proposed based on the results ofhigh performance liquid chromatography coupled with mass spectrometry （LC/MS）. It wasdeduced that hydroxyl radicals （OH） generated in the electrocatalytic process played a keyrole in oxidizing BPA to form CO₂and H₂O, which could be determined by fluorescencemethods. All these results illustrated that PbO₂-ILs/Ti electrode was effective for pollutantsdegradation and had a great potential application.（4） Series of nanomaterials containing bismuth were prepared by thermal synthesis, andtheir morphologies were controlled by changing surfactants and calcining temperature.Methods of XRD, SEM, TEM, BET, Raman spectra and UV-visible diffuse reflectancespectra （DRS） were used to characterize the nanomaterials. Results showed that thesenanomaterials were composed by many nanoplates. What’s more, the photocatalytic activities of these materials under visible light irradiation were investigated by the degradation ofrhodamine B, malachite green, and methylene blue. Experimental results demonstrated thatthe Bi₂WO₆/BiVO₄（SDBS,600C） composite photocatalysts with the concentration1.0mg/mL possessed perfect photocatalytic activity, and the degradation efficiency could reach100%under30min irradiation. Furthermore, the photocatalysts still kept high photocatalyticactivity after using6cycles. This study provides a potential effective Bi₂WO₆/BiVO₄composite photocatalysts in purifying polluted water.