| Recently,metal complex dyes based on its excellent properties have been widely used in all walks of life.Among various metal,iron on account of its relatively non-toxic has been used to synthesize dyes.At the same time,a lot of metal complex dyes wastewater was discharging into water during the process of their production,changing water environmental factors,such as the water transparency,DO,COD,causing serious pollution problems.Besides,most of metal complex dyes are toxic and potentially carinogenic and teratogenic,usually resistant to be degraded,resulting into a serious threat to water ecosystem.Among various decolorization technology,biological decolorization has drawn a lot of attention based on its advantages of cost-efficient and environmenta-friendly.However,because of the complex composition and high molecular weight of metal complex dyes,where are little bacteria which can decolore dyes efficiently.Besides,recently metal nano-particles have been widely applied to various field,such as cytalyst and photochromics production based on their small specific surface area,more activation center et al.Especially,iron nano-particles research are the most widesperead because of its abundant source and special properties.And to sum up,some scholars have proposed a new research direction:to realize efficient decolorization of metal-complex dyes and synthesis of metal nanoparticles through microbes.Up to now,it has achieved some success.However,it does have two difficulties:at one hand,fewer bacteria can decolored metal complex dyes efficiently;and another hand,the reported biossynthesis of metal nanoparticles all need additional reagents,it caused a high cost and secondary pollution.Thus,in this study,we are devoted to develop a new bacterium which can decolore metal complex dyes and synthesize metal nanomacterials without any additional reagents.We choose Pseudoalteromonas.CF10-13 to decolorize metal complex dyes(Naphthol Green B),to investigate its decolorization mechanism and metal recycling process.The main research content and results are as following:At first,based on the investigation of effects of different factors such as electron donors/accpetors,pH,DO,initial NGB concentration et al.on NGB decolorization and kinetic analysis of decolorization efficiency,the NGB decolorizing performance and kinetic discipline were analysized.Besides,through the NGB decolorization by different cells departments and FTIR analysis and UV-Vis spoectra of decolorizing products,the decolorization mechanism of NGB was revealed.The results showed that Pseudoalteromonas.CF10-13 could efficiently decolorize NGB with acetate as optimal electron donor and pH of 7.0?7.5.P.sp CF10-13 could decolor NGB completely within 500 mg/L of NGB after 72 h,the maxmium DE was 90.32%;moreover 96.30%of NGB at 1000 mg/L could be decolorized after 120h,suggesting a high decolorization capacity of NGB.Besides,the pseudo first-order kinetics showed the best fitting effect with the decolorization results.And FTIR analysis showed the functional groups involved in the bioadsorption of NGB.Combined with UV-Vis analysis of decolorizing products,the mechasnims of NGB decolorization were as the following:bioadsorption of NGB by extracellular polymeric substance;extracellular decolorization by electron transfer reaction;intracellular degradaion of intermedia products.Meanwhile,the black precipitation were synthetized along with biodegradation.TEM and SEM spectra showed the morphology and distribution of the precipitation.And XRD analysis revealed the possible composition of precipitation containing iron.It validated the possibility of the NGB decolorization and resource utilization by P.sp CF10-13.Based on the above results,the NGB decolorization mechasnims by P.sp CF10-13 were established.And P.sp CF10-13 could realize the recycling of metal which have a great siginificance on the combination of efficient decolorization with green recycling of dyes synchronously without any additional reagents. |
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