羟基磷灰石对大肠杆菌吸附铬(Ⅵ)的影响

Effect of Hydroxyapatite on Adsorption of Chromium(Ⅵ) by Escherichia coli

以实际水体作为实验用水,探究羟基磷灰石(HA)存在下大肠杆菌(E.coli)对六价铬[Cr(Ⅵ)]的捕获吸附特性。结果表明,E.coli对Cr(Ⅵ)的吸附符合假一级动力学,适宜pH值为6,该条件下E.coli对Cr(Ⅵ)的饱和吸附量为30.71 mg/g。纳米尺寸的HA释放和生物效应受浓度影响,当HA暴露浓度为5 mg/L时,正电性HA附着于细菌表面,促进E.coli与Cr(Ⅵ)接触,E.coli对Cr(Ⅵ)的饱和吸附量达到最高值55.98 mg/g。当HA暴露浓度为10~50 mg/L时,过量的HA附着在细菌表面,改变了细胞膜的通透性,因而吸附量略有降低,但依然高于E.coli单独对Cr(Ⅵ)的吸附量。当HA暴露浓度高于100 mg/L时,团聚在一起的HA对Cr(Ⅵ)也产生吸附作用,提高了体系对Cr(Ⅵ)的去除率。总体来说,HA和E.coli共同作用有助于提高对Cr(Ⅵ)的吸附效率。

The capture and adsorption characteristics of hexavalent chromium by Escherichia coli(E.coli) in the presence of hydroxyapatite(HA) were investigated in an actual water body.The adsorption of Cr( Ⅵ) by E.coli complied with pseudo-first-order kinetics,and the optimum pH was 6.Under this condition,the saturated adsorption capacity of E.coli for Cr( Ⅵ) was 30.71 mg/g.The nanoscale HA releases and biological effects were affected by concentration.When HA exposure concentration was 5 mg/L,positively charged HA attached to the bacterial surface and promoted the contact between E.coli and Cr(Ⅵ),and the saturated adsorption capacity of E.coli for Cr(Ⅵ) reached the maximum of 55.98 mg/g.When the exposure concentration of HA was 10-50 mg/L,excessive HA attached to the surface of bacteria and changed the permeability of cell membrane,so the adsorption capacity decreased slightly,but it was still higher than the adsorption capacity of Cr(Ⅵ) by E.coli alone.When the exposure concentration of HA was higher than 100 mg/L,the agglomerated HA also had adsorption ability on Cr(Ⅵ),which enhanced the removal efficiency of Cr(Ⅵ) in the system.In general,the synergistic effect of HA and E.coli can improve the adsorption efficiency of Cr(Ⅵ).