An assessment on Spirulina platensis as a biosorbent for arsenic removal

A column consisting of algal biosorbents like agar-agar, alginic acid, calcium alginate and Spirulina platensis biomass entrapped in polyurethane foam matrix was designed and tested for the removal of As(V) from the aqueous medium. The performance of the column was studied in terms of removal efficiency, metal sequestered in the column during a specified time and biosorption capacity. The observations recorded during the study showed that the removal efficiency of As(V) after 60 min of treatment varied from 0.7 to 45.0% for 25–100 μg/L initial concentrations. The best removal efficiency of As(V) was exhibited by agar-agar and S. platensis biomass combination (45%), whereas agar-agar alone showed only 18.0% removal efficiency at 25 μg/L initial concentration. The biosorption capacity of As(V) varied from 108 to 694 μg/g for 25–100 μg/L initial concentration and the highest value (694 μg/g) was recorded for agar-agar and S. platensis biomass combination. This value was 20% higher than agar-agar alone (556 μg/g) after 60 min of treatment time. The results of the present study suggest that physical entrapment of an appropriate combination of algal adsorbents in polyurethane matrix offers a cost-effective solution for the treatment of water contaminated with arsenic.