The potential use of natural vs commercial biosorbent material to remediate stream waters by removing heavy metal contaminants

Abstract

The presence of high level of heavy metals in aquatic environment is a cause of ecological and environmental concern and thus their removal from water courses is environmentally essential. Four natural inexpensive biosorbents: macro algae (Fucus vesiculosus), crab shells (Cancer pagurus), wood chippings and iron-rich soil were tested for copper (Cu2+) and zinc (Zn2+) removal from aqueous solutions. Batch equilibrations were performed at 1:100 w/v with different initial metal concentrations. Three macro algae pre-treatments (unmodified (UM algae), chemically treated (Ca-T algae) and thermally treated (T-T algae)) were additionally investigated for performance. The sorption capacities were compared with the commercial material biochar and activated carbon. The maximum level of the sorbents for Cu2+ uptake at 15.7 mM/l was attained by the natural material of UM algae (72.37 ± 0.37 mg/g) > Ca-T algae (66.77 ± 0.19 mg/g) > T-T algae (63.06 ± 0.82 mg/g), followed by the commercial material activated carbon (36.71 ± 2.20 mg/g). The maximum level of the sorbents for Zn2+ uptake at 15.3 mM/l was also achieved by the natural material of UM algae (52.40 ± 0.80 mg/g) > Ca-T algae (48.83 ± 2.01 mg/g) > T-T algae (39.57 ± 0.80 mg/g) followed by the commercial material activated carbon (20.78 ± 1.63 mg/g) and biochar (18.07 ± 1.09 mg/g). The results demonstrated that Cu2+ and Zn2+ were effectively removed by these biosorbents at all concentrations. However, at high metals concentrations, the natural material macro algae had greater Cu2+ and Zn2+ sorption capacity than the conventional sorbent activated carbon, and the affinity of these natural biosorbents were greater for Cu2+ than Zn2+. Hence, inexpensive natural and readily available materials showed potential as biosorbents to remediate polluted stream water of toxic metal contaminants.