Effect of microbes on Ni(II) diffusion onto sepiolite

The effect of Paecilomyces cateniannulatus (P. cateniannulatus) on Ni(II) diffusion onto sepiolite was investigated by batch adsorption and their interaction mechanisms were determined by surface complexation modeling. At low pH, the diffusion of Ni(II) on sepiocite and sepiocite + P. cateniannulatus systems is primarily cation exchange and inner-sphere surface complexation, respectively. P. cateniannulatus facilitated the Ni(II) diffusion on sepiocite at pH < 5.0, whereas the inhibited diffusion was observed at pH > 5.0. According to surface complexation modeling, the diffusion of Ni(II) on sepiolite can be satisfactorily fitted by diffuse layer model with single amphoteric sorption sites (SOH) and ion exchange sites (XH), whereas the three type sites (strong sites (SsOH), weak sites (SwOH) and ion exchange sites (XH)) are assumed for sepiocite + P. cateniannulatus systems. The findings presented in this study are of great importance towards the investigation on Ni(II) diffusion at the water-mineral interface in the presence of bacteria.