Preparation Of Biomimetic Gold Nanoparticles Catalysts And Their Application In The Catalytic Hydrogenation Of 4-Nitrophenol

As a toxic,structurally stable organic pollutant,4-nitrophenol has been detected from ocean,lake,river,groundwater and soil,posing a serious threat to human health,ecosystem and food safety.The conventional technique for 4-nitrophenol degradation,such as adsorption and extraction,is difficult to deal with highly polluted waters and the pollutants cannot be reused.Compared with traditional methods,the catalytic hydrogenation of 4-nitrophenol is a more simple and efficient way to deal with pollution.It can not only deal with different levels of 4-nitrophenol pollution effectively,but also generate a valuable product of 4-aminophenol.Many extensive researches have been focused on the mechanism of catalytic hydrogenation of 4-nitrophenol and catalyst development.Until now,noble metal catalysts have exhibited excellent performance in the catalytic hydrogenation of 4-nitrophenol.However,the noble metal catalysts show a strong tendency to aggregate into larger clusters during usage and recycle,resulting in the change in the size and the deactivation in the shape or the loss in the catalytic activity.Meanwhile,as for most nanomaterials,the synthetic paths are fraught with problems including the use of toxic or expensive reagents,generation of hazardous by-products and high energy consumption,which affect the development potential of nanomaterials in biological,medical and other fields.Therefore,it is important to develop catalysts with the high biocompatibility and sustainability.In this dissertation,by using the catalytic hydrogenation of 4-nitrophenol as the reaction model,two kinds of biomemitic gold nanoparticles were prepared as the catalysts.The influence of different amount of gold precursors on the morphology and catalytic performance were systematically investigated.The main work and results of this dissertation are as follows:?1?In-situ synthesis of biocompatible gold nanoparticle catalyst and their catalytic applications.In this work,a Fe₃O₄@PDA@Au catalyst with stable structure was successfully prepared through a green and simple way.The water-soluble Fe₃O₄nanoclusters exhibit controllable sizes and fast magnetic response.Polydopamine,as the reducing agent and stabilizer of the reaction,can effectively prevent gold nanoparticles from agglomeration or leaching,and there is no other reducing agent or crosslinking agent in the process of catalyst synthesis.The Fe₃O₄@PDA nanoclusters were adjusted by gold precursors with different concentrations.The results showed that the catalysts prepared by the gold precursor with a concentration of 130?M exhibited the best catalytic activity,with the catalytic rate constant of 39.2 s^-1·g^-1 and the conversion over 99%in ten minutes.Meanwhile,the recyclability of the catalyst is excellent and the conversion can remain more than 95%after a ten-times repeat.?2?Gold nanoparticle catalyst prepared using plants and domestic garbage and their catalytic application.In this work,we tried to extract effective components from plants by water extraction and the reductive detection was investigated,the extract of Lagerstroemia indica leaves exhibited excellent reduction ability at room temperature.Natural eggshell membrane was selected as the biological template of the catalyst and it can be used as a good dispersing platform for in-situ synthesis of Au nanoparticles.The preparation of ESM@LSE@Au catalyst is spontaneously prepared at room temperature,without any reducing reagents,stabilizers,surfactants.The catalyst prepared from a 0.6 mM gold precursor exhibited the best catalytic performance with a rate constant of 39.2 s^-1·g^-1 and a conversion of 99.84%over 6 minutes.In addition,the heterogeneous catalyst can be recycled after mild centrifugation and the conversion can remain over 92.40%after 10cycles.Based on the reaction model and mechanism,this dissertation is committed to the preparation of gold nanoparticle catalysts for the efficient degradation of 4-nitrophenol.On the premise of ensuring the catalytic activity and stability,the raw materials of catalysts strive to be green and sustainable,the synthesis route strives to be simple and low energy consumption.Both two biomimetic catalysts have shown excellent catalytic performance in the catalytic hydrogenation of 4-nitrophenol.