Application Of Ceramic Precursor Polymer In Environmental Analysis And Catalysis

Liquid ceramic precursor materials have attracted wide attention due to their advantages such as high melting point,high hardness,high wear resistance,and oxidation resistance.In this study,a ceramic precursor polymer solution of poly vinylsilazane was been used as coating material on SiO2 particles to surface synthesize gold nanoparticles,and then the substrate was applied to catalytic degradation reactions of the toxic organic pollutants rhodamine 6G and p-nitrophenol in water.In addition,another type of ceramic precursor-allylhydridopolycarbosilane was been selected as coating material to modify polycarbonate membrane surface property for enhancing behavior of electroosmosis pump.The specific research content divide into the following three parts1.Preparation catalyst supports.The catalysts are prepared by surface reducing of Si-H bonds in the polyvinylsilazane molecules followed by polymer consolidation to form solid gold nanoparticles.The polymer coating was proceeded by two steps of curation to keep active Si-H functional group:light curing and heat curing.The active Si-H groups on the catalyst supports measured by the traditional sodium thiosulfate titration and elctrogenerated bromine methods.The bromine molecules react with Si-H functional groups,and the remained Si-H content are calculated by consuming volume of the thiosulfate.Roughly,the calculated value is 2.5 × 10-4 mol Si-H sites exist in each gram of PVSZ before loading gold nanoparticles,and some Si-H could be remained for loading gold nanoparticles.Then,the prepared catalyst had characterized by TEM,IR,XPS and other characterization methods,to illustrate the case of gold nanocatalyst supported by polyethylene-silazane in ceramic precursor2.The gold nanoparticles supported by polyvinylsilazane has applied to degradate rhodamine 6G and p-nitrophenol molecules in water.In the process of removing rhodamine 6G,hydrogen peroxide solutions used for oxidant to explore the influence of different factors on its catalytic effect.The results showed that the higher the content of oxidant,the faster the catalytic efficiency.The gold nanoparticles reduced by PVSZ under the condition of chlorauric acid of pH 4.5 were smaller in size and uniform in shape,with better dispersion and stronger catalytic capacity for rhodamine 6G.The catalytic degradation efficiency of rhodamine 6G was the best under the condition of 360-nm ultraviolet light and temperature setting at 30?,and the catalytic efficiency reached 96%after 60 min of reaction.Moreover,the catalytic efficiency reachs 89.1%after being recycled for five times.In the process of p-nitrophenol degradation,sodium borohydride was used as reducing agent to explore the influence of different factors on its catalytic effect.The results shows that the chlorauric acid under acidic conditions exhibite better catalytic effect and could completely remove p-nitrophenol within 30 min.The conversion rates less changed after being recycled for five times,which is only decreased by 8.9%,indicating that the catalyst had good catalytic activity and cyclic stability and was easy to be recycled.3.The allylhydridopolycarbosilane modified polycarbonate membrane had used as a porous media membrane to enhance electroosmotic pump performance,and it applied to titration experiments to determine the hardness of water.Scanning electron microscopy and energy spectrum analysis have proved that polycarbosilane can coat the film well and silicate vitrification,making the film stable and resistant to organic solvents as well as long durablity.The flow rate of the electroosmotic pump with modified membrane reached 89.13 ?L/min at the voltage of 20 V and pH of 10,while the flow rate of the unmodified membrane is only 37.89 ?L/min.After three days of operation,the relative standard deviation(RSD)value of the flow rate of electroosmotic pump with the modified PC membrane is 0.6%,and it is reusable.Then it was applied to the determination of water hardness.Compared with the traditional experiments,the developed electroosmotic pump has small reagents consumption and shows low relative average deviation(0.11%)with well reliablity.