Potential application of Allium Cepa seeds as a novel biosorbent for efficient biosorption of heavy metals ions from aqueous solution

Abstract

Abatement of pollutants i.e. heavy metals by using green biomaterials is an emerging area of interest due to its cost-effective and renewability. In the present study, the potential of Alium Cepa seed biomass (ACSB) as a novel biosorbent for the adsorption of Cr(VI), Cd(II), Zn(II), Cu(II) and Pb(II) was investigated. The FTIR spectrum of ACSB confirmed a presence of surface OH bond, an essential functional group for metal uptake. Biosorption factors such as pH (2-10), time (15–190 min), dosage (1–5 g/L) and initial metal concentration (50–200 mg/L) were optimized at the ambient conditions. The equilibrium adsorption time was obtained at 90 min for Cd(II), Cu(II) and Pb(II), as well as 120 min for Cr(VI) and Zn(II), respectively, for the mentioned metal ions removal. The maximum removal efficiency was obtained at 4 g/L of ASCB for 50 mg/L adsorbate and a neutral pH. Under this condition, the maximum uptake was 0.67, 1.50, 1.68, 1.03 and 1.75 mg/L for Cr(VI), Cd(II), Zn(II), Cu(II) and Pb(II), respectively. Monolayer biosorption was determined for the studied heavy metals. The removal of the metal ions by ACSB followed a pseudo 2nd order sorption kinetics. The results suggested that ACSB is more suitable to remove (99%) Pb(II), Cu(II), Cd(II) as compared to Zn(II) and Cr(VI).