Biosorption of Cadmium, Lead and Chromium from Aqueous Solution Using Mountain Ebony Pod

Abstract

Cadmium (Cd), lead (Pb), and chromium (Cr) are among the known hazardous metals that have detrimental effects on ecosystem as well as human beings. Biosorption of Cd(II), Pb(II) and Cr(VI) from aqueous solutions by Mountain Ebony pod (ME) powder using batch technique was researched in the present study. The ME material was characterised using Fourier transform infrared (FTIR) spectroscopy and Scanning electron microscopy (SEM). The biosorption study was investigated as a function of pH, biosorbent dosage, contact time, initial metal ion concentration, and temperature. The kinetic study showed that the biosorption of the Cd (II), Pb (II) and Cr (VI) ions followed pseudo second order kinetic model while the equilibrium data followed the Langmuir model. The maximum biosorption capacities of ME for Cd (II), Pb (II) and Cr (VI) were 68.07, 61.25 and 40.47 mg g–1, respectively. Thermodynamic parameters (ΔGo and ΔSo ) revealed that the biosorption processes for the three metal ions were feasible and spontaneous, and the randomness at the biosorbent-metal solution interface increased. The values of standard enthalpy change (ΔHo ) indicated that biosorption process for Cd (II) was endothermic whereas the processes Pb (II) and Cr (VI) removal by ME powder were exothermic. The results of the study showed that ME biosorbent could be used as an alternative, low-cost, green and eco-friendly material for removal of Cd (II), Pb (II) and Cr (VI) ions from aqueous solutions and wastewater.