Regulation Of Arsenic Pollutants By Environmental Microorganisms And Synthesis Of Gold Nanoparticles

Microorganisms play an important role in biogeochemical cycling,and participate in the cycling of carbon,nitrogen,phosphorus,arsenic,zinc,gold,iron and other elements in the environment.In recent years,arsenic pollution is a problem,moreover,some industrial sludge contain high concentrations of arsenic and other heavy metals.At present,the domestic for industrial sludge treatment method mainly has enrichment process,encapsulation-dehydration,etc.,these conventional methods are not very good in dealing with sludge of high arsenic,these are the potential hazard to environment.Therefore,it has become an important research direction about how to regulate and control the arsenic in industrial sludge.At present,the application of metal nano-materials is more and more widely with its unique characteristics,it is widely used in the fields of catalyst,medicine,adsorbent and so on.Because of its low cost and low pollution,the biosynthesis of nano materials has attracted more and more attention.The main research contents of this work were:(1)isolation of a Rhodococcus sp.LSJ-6 from As-polluted soil sample;(2)examining the effect of Rhodococcus sp.LSJ-6 on arsenic and other elements in industrial sludge under static and dynamic condi-tions;(3)study of the AuNPs synthesis of Rhodococcus sp.LSJ-6 under different temperature and pH environment.The results of the study are as three follows:(?)The screening of aerobic arsenic resistant bacteria were isolated from the soil sample of Hunan Province,it was found a arsenic reducing bacteria,named Rhodococcus sp.LSJ-6.Rod-shaped,gram positive bacteria,pale yellow colonies.The optimum growth condition is 30 OC,pH 7,the NaCl concentration is 10-15 mg/L.Arsenic resistance test showed that the resistance range of As(V)was 5-20 mM,when the concentration of As(V)was less than 5 mM,the strain can normal grow and the growth was inhibited when the concentration was greater than 20 mM.The results for the Hunan province arsenic reduction strain diversity provides the basis and provide evidence for the mechanism of arsenic resistant strains.(?)The arsenic transformation and release in industrial sludge by Rhodococcus sp.LSJ-6 in the static and dynamic environment was studied.It was found that LSJ-6 could release arsenic,iron,zinc and chromium in industrial sludge in static environment.Moreover,it can rapidly reduce the dissolved As(V)to As(III).In addition,As(V)can not be reduced to As(III)in dynamic environment.XANES analysis showed Fe(II)existed in the sludge and solution.The study shows the regulation effect of arsenic reducing bacteria on arsenic sludge in the elements with aerobic condition,ArrC containing arsenic reducing bacteria has an important role in the regulation of industrial sludge containing heavy metals in the system,it provides a reference for the treatment of industrial sludge.(?)Rhodococcus LSJ-6 synthesized gold nanoparticles under the effect of temperature and p H was studied,it found temperature and pH had important effect on the size and morphology of gold nanoparticles.Temperature and pH were mainly influence of particle size and morphology of gold nanoparticles,and small size of gold nanoparticles can be synthesized with high pH.In addition,the adsorption of methylene blue on the synthesized gold nanoparticles was studied and it was found that the highest adsorption rate reached to 96%.It is possible that the surface enhanced Raman scattering(SERS)method can be used for the detection of methylene blue in pollutants.