Heavy metal adsorption from aqueous solution using Eichhornia crassipes dead biomass

The adsorption of Zn(II), Cd(II) and Cr(VI) from single, bi- and tri-metal systems was studied with respect to varying metal and biomass concentration, pH and agitation time on Eichhornia crassipes dead biomass. The maximum adsorption of Cd(II) and Zn(II) was observed at pH 5 and 6 respectively, whereas that of Cr at pH 2.0. An enhanced metal adsorption on 0.5 g of biomass with an agitation time of 120 min for Zn(II) and Cd(VI) and 180 min for Cr was recorded. Maximum adsorption of Cd(II) (12.4 mg g− 1), obtained from initial concentration (40 mg l− 1), followed by Zn(II) (9.3 mg g− 1) and Cr (5.6 mg g− 1) at optimal conditions. Cd adsorption capacity increased in the bi-metal system whereas that of Zn and Cr reduced in both bi- and tri-metal systems. After elution, higher metal recovery was recorded from a single metal system than a trimetal system. E. crassipes dead biomass retained the metal adsorption capacity up to two cycles, indicating its prospects for the wastewater treatment and metal recovery.