| Nanomaterials typically refer to materials with a nano-size of less than 100 nm,Nanomaterials have large specific surface area and high surface energy,which increases the chance and ability to interact with other molecules.Therefore,nanomaterials have strong potential application value.For example,metal nanomaterials can have antibacterial,anti-cancer,catalytic,magnetic and optical activities.Quantum dots was a kind of semiconductor nanomaterials with quantum confinement,particle size smaller than or close to the radius of Bohr excitons and mainly composed of Ⅱ-Ⅳ or Ⅲ-Ⅳ-group elements.Nanoscience research and its applications developed in recent decades have had a great impact on many information technology,energy,environmental science,medicine,and food safety.The technology of synthesizing various inorganic metal nanomaterials has been widely used in biology,chemical sensors,bioimaging,biocatalysis,photochemistry,drug delivery and new energy.In the preparation process of nanomaterials,conventional physical and chemical methods usually require high temperature conditions and high pressure conditions,and need to add chemical reducing agents and synthetic stabilizers,which will cause material production costs,pollutant emissions.Increasing difficulty in subsequent processing.Biological methods are green and environmentally friendly,and do not require these strict environmental conditions and additional chemical substances.Bio-nanoparticle synthesis can also adjust and optimize the shape and size of synthetic metal nanoparticles by controlling conditions such as temperature,p H,precursor concentration,and synthesis reaction time in the environment.Therefore,the method of bioreducing and synthesizing nanomaterials with microorganisms has become a relatively novel way to prepare metal nanoparticles.(1)We isolated and screened two halophilic bacteria in Zhejiang Zhoushan Salt, and identified them as Staphylococcus saprophyticus JJ-1,Halomonas sp.zqy,and their synthesized nanomaterials based on the results of gene sequence.For the treatment of organic pollutants,we know that most industrial organic wastewater such as dyes was mostly high-salt wastewater,and microorganisms that do not have salt-tolerance(tolerance)were difficult to play their degrading effect in a higher salt concentration environment,and use halophilic or halophilic bacteria to degrade.High-salinity wastewater containing organic pollutants was particularly important.(2)Using a salt-tolerant gram-positive bacterium S.saparophytics JJ-1 screened out in the laboratory,under anaerobic conditions,pyruvate and palladium ions can be used as electron donors and electron acceptors,respectively,to realize Bio-Pd NPs.The physical and chemical characterization methods were used to further explore the morphological and structural characteristics of Pd NPs.At the same time,the effect of the amount of Pd(Ⅱ)added on the reduction of palladium and the effect of in-situ reduction of o-chloronitrobenzene was investigated.Studies had found that nano-palladium was mainly dispersed on the cell surface.Control experiments prove that bacteria and Bio-Pd nanoparticles had a synergistic catalytic effect and could promote the degradation of o-chloronitrobenzene.In addition,we also studied the possible reduction products of o-chloronitrobenzene,and inferred the possible reduction pathways and the maximum concentration of ochloronitrobenzene.(3)Halomonas sp.zqy biosynthesizes ZnS QDs in a high-salt environment.This was the first time that halophilic bacteria had been used to synthesize ZnS QDs.In addition,the photocatalytic performance of the synthesized ZnS QD was examined using the dye MG as a model pollutant.The research results show that the synthesized quantum dots could degrade malachite green under ultraviolet light catalysis.Finally,the photocatalysis mechanism of bio-nanomaterials was investigated,and the degradation products of its catalytic degradation were analyzed.This work demonstrates a green,safe,and environmentally friendly method for the synthesis of ZnS QD,and used this method to provide a new method for the degradation of organic pollutants.In addition,we also found that Halomonas sp.zqy can synthesize CdS QDs,which have good fluorescence properties. |
