The Equilibrium, Kinetics, and Thermodynamics Studies of the Sorption of Methylene Blue from Aqueous Solution Using Pulverized Raw Macadamia Nut Shells

Joshua N Edokpayi; Samson O Alayande; Ahmed Adetoro; John O Odiyo

doi:10.1155/2020/8840666

The Equilibrium, Kinetics, and Thermodynamics Studies of the Sorption of Methylene Blue from Aqueous Solution Using Pulverized Raw Macadamia Nut Shells

J Anal Methods Chem. 2020 May 30:2020:8840666. doi: 10.1155/2020/8840666. eCollection 2020.

Authors

Joshua N Edokpayi¹, Samson O Alayande², Ahmed Adetoro³, John O Odiyo¹

Affiliations

¹ Hydrology and Water Resource Department, University of Venda, Thohoyandou, South Africa.
² Department of Physical Sciences, First Technical University, Ibadan, Nigeria.
³ Department of Chemical Sciences, Yaba College of Technology, Lagos, Nigeria.

Abstract

In this study, the potential for pulverized raw macadamia nut shell (MNS) for the sequestration of methylene blue from aqueous media was assessed. The sorbent was characterized using scanning electron microscopy for surface morphology, functional group analysis was performed with a Fourier-transform infrared spectrometer (FT-IR), and Brunauer-Emmett-Teller (BET) isotherm was used for surface area elucidation. The effects of contact time, sorbent dosage, particle size, pH, and change in a solution matrix were studied. Equilibrium data were fitted using Temkin, Langmuir, and Freundlich adsorption isotherm models. The sorption kinetics was studied using the Lagergren pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion models. The feasibility of the study was established from the thermodynamic studies. A surface area of 2.763 m²/g was obtained. The equilibrium and kinetics of sorption was best described by the Langmuir and the pseudo-second-order models, respectively. The sorption process was spontaneous (-ΔG ⁰=28.72 - 31.77 kJ/mol) and endothermic in nature (ΔH ⁰=17.45 kJ/mol). The positive value of ΔS⁰ (0.15 kJ/molK) implies increased randomness of the sorbate molecules at the surface of the sorbent. This study presents sustainable management of wastewater using MNS as a potential low-cost sorbent for dye decontamination from aqueous solution.