Preparation And Catalytic Performance Of Noble Metal Nanoparticles Based On Amphiphilic Molecular Stabilization

Organic pollutants contained in industrial wastewater seriously endanger human life and health.Although noble metal nanoparticles can catalyze the degradation of organic pollutants,they are susceptible to serious aggregation in aqueous solutions,which reduces their catalytic performance.Looking for a suitable carrier to prepare a precious metal nanoparticle catalyst with small size and good stability is a problem that needs to be solved urgently.In this paper,from the perspective of improving the utilization rate of the catalytic active sites of noble metal nanoparticles,the nanomicelles were used to control the size and stability of the noble metal nanoparticles.The preparation,catalytic and antibacterial properties of precious metal nanoparticles were studied,and the method of precious metal nanoparticles stabilized by micelle was established.The specific research content is as follows:First of all,PEI-C₁₄ amphiphilic molecules were synthesized using Myristic acid bonded polyethyleneimine,which self-assembled in water to form micelles with an average hydrodynamics size of 23.1 nm.PEI-C₁₄ micelles were used as the carrier to load gold nanoparticles?AuNPs?and palladium nanoparticles?PdNPs?,the sizes of AuNPs and PdNPs in the prepared PEI-C₁₄-AuNPs_n and PEI-C₁₄-PdNPs_n were both 1-4 nm and uniformly dispersed.The precious metal nanoparticles located in the micelle shell more easily contacted with the reactive substrate during the catalysis process to greatly improve the catalytic efficiency.The catalytic rate constant of PEI-C₁₄-PdNPs₅₀₀ for 4-NP was K_nor=5309.7 s^-1M^-1,indicating a high catalytic efficiency.In addition,PEI-C₁₄-AuNPs_n and PEI-C₁₄-PdNPs_n effectively degraded organic dyes methylene blue?MB?and rhodamine B?RhB?in the presence of H₂O₂.The catalytic rate constants K_nor of PEI-C₁₄-PdNPs₃₀₀ for MB and RhB are 299 min^-1M^-1 and 379 min^-1M^-1,respectively,showing higher catalytic efficiency.Secondly,to resolve the problem of small size of PEI-C₁₄ micelles,the more hydrophobic oleic acid was reacted with PEI to synthesize the PEI-C₁₈ amphiphilic molecule which was used to prepare the PEI-C₁₈ micelles with a hydrodynamic size of 196nm.PEI-C₁₈-AuNPs_n and PEI-C₁₈-PdNPs_n prepared by PEI-C₁₈ micelle had the characteristics of small size,high dispersion and good stability.Catalytic performance results showed that:PEI-C₁₈-PdNPs₁₅₀ had the highest catalytic efficiency for 4-NP,K_noror was 18.53 s^-1mM^-1;PEI-C₁₈-AuNPs_n and PEI-C₁₈-PdNPs_n also showed good catalytic degradation effect on morin which was completely degraded within 15 min in the presence of H₂O₂.PEI-C₁₈-PdNPs₁₅₀ had the smallest size and the best catalytic performance,K_noror was 143.57 s^-1M^-1.At last,the antibacterial properties of prepared polymer micelles and noble metal nanoparticle catalysts against E.coli and S.aureus were studied.The experimental results showed that the bacterial inhibition rate of the samples increased with the increasing sample concentration.The bacterial inhibition rates of two samples were 100%,when the[N]concentrations in the PEI-C₁₄-PdNPs₃₀₀ and PEI-C₁₈-AuNPs₅₀ samples were 0.15 and 0.025mol·L^-1,respectively.