Removal of Heavy Metals from Aqueous Solution by Waste Biomass

Abstract

1. The highest equilibrium uptake (q) was observed at 1 g biomass concentration for Zn2+ (3.7 mg g-1), Cr6+ (3.9 mg g-1), Ni2+ (4.2 mg g-1) and Pb2+ (6.4 mg g-1) at 25 mg L-1. 2. The metal uptake (q) was increased with an increase of the initial Zn2+ and Pb2+ concentration up to 50 mg L-1 by waste biomass (MB2) in both single and binary metal biosorption system. The metal uptake (q) was higher for Zn2+ than those for Pb2+ at lower concentrations (5 to 10 mg L-1) that subsequently lowered at higher concentrations (15 to 50 mg L-1) for both single and binary metal biosorption system. 3. The adsorption capacity (Kf) of the waste biomass (MB2) for Zn2+ (1.5) was higher than Pb2+ (0.8769) in single metal sorption system whereas it was 3.28 and 2.4 respectively in binary metal sorption system. 4. The adsorption capacity (Kf) of the waste biomass (MB2) for the Zn2+, Pb2+, Cr6+ and Ni2+ was always lower in single (1.50, 0.88, 0.60 and 2.45) metal sorption system than that for the multimetal (0.71, 0.66, 0.55 and 1.55) sorption system. 5. Waste biomass (MB2) biomass possessed maximum sorption capacity (Kf) for Cr6+ and Zn2+ at pH ranging from 4 to 5 in single and 3 to 4 in multimetal sorption system, while insignificant metal uptake (q) of Pb2+ and Ni2+ was noticed in both single and multimetal sorption system. 6. The preference of metal sorption was Cr6+>Pb2+>Zn2+>Ni2+ in single metal sorption system whereas in multimetal sorption system it was Zn2+>Cr6+>Ni2+>Pb2+. 7. At pH between 3 and 4 there was maximum metal uptake (q) of Cr6+ (2.70 mg g-1) followed by Zn2+ (1.8 mg g-1), Ni2+ (1.77 mg g-1) and Pb2+ (0.47 mg g-1) from 25 mg L-1 of metal containing solution by waste biomass (MB2) possessed in multimetal sorption system whereas at pH 4 the biomass MB2 showed maximum metal uptake of Cr6+ (2.43 mg g-1) followed by Zn2+ (2.21 mg g-1), Pb2+ (2.14 mg 71 g-1) and Ni2+ (1.6 mg g-1) from 25 mg L-1 of metal containing solution in single sorption system. 8. The pattern of adsorption capacities (Kf) was found as Ni2+ (2.45) > Zn2+ (1.50) > Pb2+ (0.88) > Cr6+ (0.60) in single metal sorption system whereas it was 1.55, 0.71, 0.66 and 0.55 respectively in multimetal sorption system. 9. This study showed that waste biomass (MB2) generated in great quantities can be used for metal uptake in waste water treatment of different metal finishing industries.