Construction Of Composite Silicon/gold Nanoparticles Composite System And Detection And Transformation Of Phenol Pollutants

The long-term existence of phenolic pollutants in the environment will have a serious impact on the soil and water environment.The accurate detection and effective degradation of phenolic pollutants are important research contents in the neighborhood of environmental analysis.Mesoporous silicon has a wide range of applications in molecular transfer,separation,sensing and catalysis because of its unique mesoporous structure,adjustable surface and good biosafety and compatibility.In this paper,a fluorescence signal enhanced detection system based on mesoporous silicon was constructed to realize the highly sensitive and selective detection of hydroquinone pollutants,and a rapid catalytic reduction detection system of nitrophenol pollutants was constructed based on the in-situ growth of gold nanoparticles on the surface of mesoporous silicon microspheres.It mainly includes the following contents:（1）In this chapter,a Rhodamine B loaded mesoporous silicon microsphere coated with gold nanoparticles is proposed to detect hydroquinone by stimulation response principle.In this method,the signal reagent Rhodamine B was loaded on mesoporous silicon after amino functionalization,and combined with gold nanoparticles with catalytic effect to construct a stimulus response analysis system.The construction process and products were characterized and analyzed by scanning electron microscope,infrared absorption spectroscopy and UV-Vis absorption spectroscopy,to explore the response performance of the system to hydroquinone,and study the selectivity and sensitivity.It is found that the fluorescence intensity will increase with the increasing concentration of hydroquinone.There is a good linear relationship in the range of 0.03-10μmol L^-1,and the detection limit is 0.01μmol L^-1（3σ）.In addition,the standard addition recovery experiment was carried out on the lake water sample.The recovery is between 92.1-109.6%,and the relative standard deviation（RSD）is less than2.6%.The experimental results show that this method is a reliable and effective method for the determination of hydroquinone.This method has high sensitivity and selectivity and has great potential application value in the detection of environmental water samples.（2）In this chapter,mesoporous silica microspheres with different sizes of gold nanoparticles grown in situ on the surface are proposed as catalysts for the catalytic reduction of 4-nitrophenol in the presence of Na BH₄reductant.It was found that the catalytic rates of4-nitrophenol with the same concentration were different for the mesoporous silica microspheres coated with different sizes of gold nanoparticles.The principle of catalytic reaction was studied by UV-Vis absorption spectroscopy,and the optimal conditions such as the type,dosage and reductant concentration of nanocatalyst were investigated.The recycling experiment of nanocatalyst was carried out.When the concentration of reducing agent is2×10^-2mol L^-1,the concentration of hydrosilylation mesoporous silicon is 0.6 mmol g^-1and the amount of nanocomposite catalyst is 7 mg,the optimal condition for catalytic reduction is obtained,and the catalytic rate constant k_appof 4-nitrophenol is 0.0925 min^-1.The k_appof the nano catalyst decreased to 0.05 min^-1after four cycles.In addition,the catalytic reduction of2-nitrophenol and 3-nitrophenol by nanocomposite catalyst was also studied.It was found that the catalyst can also effectively catalyze the reduction of these two isomers.Finally,the prepared nanocatalyst is used for the reduction of 4-nitrophenol in laboratory wastewater.Compared with 4-nitrophenol in pure water,its catalytic rate is reduced,but it can still realize the effective conversion of 4-nitrophenol to 4-aminophenol.