Biosorption of lead ions from aqueous solution by Clostridium tyrobutyricum immobilized in macroporous Ca-alginate-lignin beads

Aims: The adsorption of lead ions from aqueous solution by macroporous Ca-alginate-lignin (MCAL) beads immobilized with Clostridium tyrobutyricum and free strains was evaluated. Methods and Results: The effects of different factors including pH, adsorption time, adsorbent dosage and initial concentration of lead ions were explored. Different characterization methods were used to evaluate the adsorption process of lead ions. Meanwhile, the adsorption kinetics models and adsorption isotherm models were applied. The fitting results showed that the adsorption behaviour of C. tyrobutyricum immobilized in MCAL beads and free strains was better described by the pseudo-second-order kinetic model and the adsorption process followed the Langmuir isotherm model. The maximum biosorption of lead ions by C. tyrobutyricum immobilized in MCAL beads and free strains was 144.9 and 106.4 mg/g respectively. Conclusions: The C. tyrobutyricum immobilized in MCAL beads proved to be practicable and had better adsorption effects on lead ions compared with the free strains. Significance and Impact of the Study: The paper demonstrated a new insight and strategy for the effective treatment of lead ions from aqueous solutions by the novel function of C. tyrobutyricum.