Extracellular polymeric substances (EPS) extracted from iron bacteria can promote the iron aggregation and then form iron minerals by stabilization and deposition actions of ferric ions.In this paper,based on the key regulation or influence on ferric bio-mineralization by iron bacteria or their EPS,the authors introduced the biomineralization formation of iron oxyhydroxides in soluble EPS-containing solutions from Acidithiobacillus ferrooxidans cultures without/with Fe(Ⅱ) or Fe(Ⅲ) at various molar rates of Cl-/SO42-.It mainly described the change of solution pH values and the phases and structures of the formed iron minerals characterized by XRD,FTIR and FESEM.The decrease of solution pH values and the characterization results suggested that the micro-sphere schwertmannite covered by "pincushion" or nano-spheroid schwertmannite and micro-prism jarosite particles could form in all reaction solutions.The resulting iron precipitates uld be regulated by bacterial EPS,which,however,hardly had impact on ferrous oxidation,and addition of iron salts could promote the transformation of initial schwertmannite into jarosite phase.It was also demonstrated that phase transformation and particle agglomeration could be prevented with the increase of Cl-/SO42-molar ratios (i.e.increase of Cl-content).This might be related to the higher SO42-content occurring in the reaction solutions,which facilitated phase transformation of iron minerals and presence of the tightly assembled spheroid particle morphology.%铁细菌胞外多聚物作用下聚集的铁可通过氧化或者沉淀作用使铁稳定或沉积,从而形成铁矿物.本文基于铁细菌胞外多聚物(extracellular polymeric substances,EPS)对铁矿物形成的调控作用,介绍了Cl-/SO42-的Fe(Ⅲ)或Fe(Ⅱ)盐作用下,含可溶性EPS的氧化亚铁硫杆菌(Acidithiobacillus ferrooxidans)溶液中铁矿物的形成,观察了溶液pH值变化及形成铁矿物的矿相与结构,并采用XRD、FTIR和FESEM对其进行表征.结果发现反应溶液中OH-离子可与Fe3+形成微米级“针垫”聚集球状或纳米级小球形施威特曼石和微米级“菱形”块状黄钾铁矾铁矿物沉淀.反应溶液中的可溶性EPS可调控和促进铁矿物的形成,但对Fe2+的氧化未产生影响;外源Fe盐可促进施威特曼石向黄钾铁矾转化.随着Cl-/SO42-摩尔比例的增加(即Cl-含量的不断增加),两矿相间的转化明显受到抑制,且铁矿物颗粒之间的集聚作用明显减弱;反之,SO42-含量升高时,有利于铁矿物间的转化和聚集球状颗粒形貌结构的形成.
展开▼
