Biomineralization Of Au³⁺in Three Kinds Of Solution By Deltia Acidovorans

The maldistribution of gold in nature and over-exploitation lead to the formation of lean ore,goaf and supergene ore.These ores contain low-concentration gold,and it will cause the loss of gold if they are mishandled.At the same time,the demand for gold does not decrease all over the world.Therefore,the recovery of low-concentration Au3+ in mining wastewater and industrial sewage possess great potential.Microbial method is low-cost and efficient in recovery of noble metal with less or without environmental contamination in comparison to conventional physical or chemistry methods,so it is worth exploring further.This paper selected a strain with excellent effects in gold recovery to study the removal and biomineralization of Au3+.We use this strain to study the removal and biomineralization effects of gold in the presence of Cu2+,Zn2+,Pb2+,Pt3+,Cr6+;Eventually,we investigate the change and destination of gold in electroplating wastewater and electronic waste after treating with the strain.Specific research contents and results are as follows:First of all,a gold resistance strain was isolated from a landscape lake and was identified as Delftia FZUL-63 by 16S rDNA sequencing.Batch experiments were conducted to study the process of removal and biomineralization of Au3+.At the temperature of 30?,the removal of Au3+ by Delftia FZUL-63 is evident with 97%removal rate under the condition of pH 5.5,initial Au3+ concentration 200mg/L.The removal rate can reach 80%when initial concentration of Au3+ is as low as 10mg/L,so the Delftia FZUL-63 is suitable for recovery of low-concentration Au3+.And the gold nanoparticles,formed on the cell surface and the vicinity of the cell,were analyzed by XRD,SEM,TEM.Secondly,we explore the interaction between Delftia FZUL-63 and Cu2+,Zn2+,Pb2+,Pt3+,Cr6+,Ag+.We find that Delftia FZUL-63 can remove a certain amount of Pb2+ with 50%removal rate under the condition of 200mg/L Pb2+.The reaction product of Pb2+ and Delftia FZUL-63 was confirmed as Pbs(PO4)3OH by XRD.The removal speed of Au3+ by Delftia FZUL-63 slowed down in the presence of Cu2+,Zn2+,Pb2+,Pt3+,Cr6+ respectively,while the removal amount of Au3+ decreased scarcely eventually.Finally,after treated with Delftia FZUL-63,the removal rate of Au3+ in electroplating wastewater and electronic waste digestion solution can reach 95%and 76.7%under the condition of 147.9mg/L Au3+ and 154.1 mg/L Au3+ respectively.Cu2+,Zn2+,Pb2+,Cr6+ decreased rarely,but the removal amount of Pb2+ decreased a lot compared with the absence of Au3+.This result is likely to be attributed to the prior biomineralization of Au3+ by Delftia FZUL-63,which weaken the removal and biomineralization effect of Pb2+ by Delftia FZUL-63 after removal of abundant Au3+.SEM,TEM,XRD,XPS results indicated the formation of gold nanoparticles.It means that Delftia FZUL-63 can remove Au3+ in electroplating wastewater and electronic waste digestion solution selectively,and Au3+ were converted into gold nanoparticles.Based on above results,Delftia FZUL-63 possess certain practical significance in the recovery and biomineralization of Au3+.It is expected to be applied in pilot plant testing or in industrial practice.