Kinetics and Thermodynamic Study of Batch Adsorption Removal of Heavy Metals in a Synthesized Effluent using Raw and Alginate-Functionalised Shea Husks

Abstract

In this study adsorption of synthesized solution lead [Pb+2], copper [Cu2+], cadmium [Cd2+] and nickel [Ni2+] onto Raw Shea butter [RSBH] and modified Shea butter husk [MSBH] was investigated. Fourier transform infrared spectroscopy [FT-IR], scanning electron microscopy coupled with energy dispersive analyzer [SEM-EDAX], and Brunauer-Emmett-teller [BET] surface area analyzer were used for characterization of the adsorbents. FT-IR revealed that the COOH-NH2- and OH- are the major functional groups responsible for the sorption. The SEM-EDAX morphology indicated the presences of pores, cavities and the appearance of the metal iron after sorption. Batch adsorption study on effect of contact time and kinetics study on the sorption variations of the metal ions were analysed. Pseudo-second order equation gave qe¬ (calc.) of amount adsorbed of 23.75 mg/g as against qe[exp.] of 23.96 mg/g on sorption of RSBH on Pb(II). Pb (II) recorded the highest percentage removal [90%] for all sorbents indicate. The highest amount adsorbed for most of the metal ions was achieved within a contact time of 5 minutes. Thermodynamic parameters were evaluated and negative value of free Gibbs energy (ΔG0) -80.37 and -1.146 KJ/mol-1 was obtained for RSBH-Cu and RSBH-Ni respectively, and (-23.56,-32.43 and -0.034) for all modified samples with exception of Ni (II). This depicts the reactions as feasible and spontaneous.