Thermodynamics and Adsorption Efficiencies of Low Cost Natural Adsorbents for the Remediation of Toxic Metals from Modeled Single Component Wastewater

Abstract

The thermodynamics and sorption efficiencies for the remediation of Cr, Ni and Cd from their single component aqueous solutions (wastewater) using Maize Cob (MC) and Sawdust (SD) in a batch system are reported. Efficiencies were judged based on parameters such as sorbent weight, initial adsorbate loading concentration, pH and surface area. Shimadzu AA650 Double Beam Atomic Absorption/Flame spectrophotometer was employed to study concentration differences before and after the adsorption process. Parameters such as ΔH, ΔS and ΔG were determined. On MC, ΔH varied as 1,466.59, 1,271.21 and 1,347.70kJmol^-1 for Cr, Ni and Cd respectively. While on SD it varied as -566.85, 256.32 and 888.77kJmol^-1 respectively for the same order of metal ions. The three ions were found to be chemisorbed onto MC, while on SD Cr and Ni were physisorbed and Cd remains chemisorbed as suggested by Freundlich isotherm.

Keywords: Adsorbate, Adsorbent, Maize cob, % removal, Sawdust, Wastewater