Equilibrium, Kinetic and Thermodynamic Studies of Dyes in Aqueous Solution onto Iron Nanocomposite Stabilized by Irvingia gabonensis Leaf Extract

G.U Obuzor,P Adowei,S.E Ebong

doi:10.4314/jasem.v25i12.12

Abstract

Elimination of dyes in contaminated water or wastewater has become a universal challenge because of their colouration, toxicity, mutagenicity and carcinogenicity when discharged into the recipient environment without treatment and several technologies have been developed to deal with this problem. This paper reports the potential of exploring the use and comparison of conventional iron zero-valent (nZVI) nanoparticle and Irvingia gabonensis stabilized iron nanocomposite (Ig-nZVI) for the elimination of methyl red (MR) and methyl orange (MO) dyes in aqueous solution under effect of different experimental conditions of adsorbent dosage, initial dye concentrations, pH, contact time and temperature. Data obtained show an increase in percent dye elimination as the amount of adsorbent increased. The optimal removal of MR and MO occurred in ˂ 60 min of the start of each experimentation, obtained at a maximum pH of 5.1 at 98.5% and 80.6% for adsorbent dosage of 0.3g/50 mL and 20 mg/L initial dye concentration at temperature of 27oC. The experimental data fitted the Lamgmuir isotherm with maximum adsorption capacity (qmax) of 166.7mg/g (Ig-nZVI) and 83.35 mg/g (nZVI) for MR while 128.21 mg/g (Ig-nZVI) and 40.02.5 mg/g (nZVI) were obtained for MO. Kinetics studies showed that the removal of MR and MO fitted the pseudo second-order model. The adsorption of MR and MO were endothermic and spontaneous with enthalpy values of 3.39kJ/mol (Ig-nZVI) and 776.26kJ/mol (nZVI) and standard Gibbs free energy values of -5.95kJ/mol (Ig-nZVI) and -12.00kJ/mol (nZVI). Thermodynamic studies (ΔG < 0, ΔH < 0, ΔS > 0) implied a spontaneous and exothermic process in nature. The adsorption of MO was endothermic and spontaneous with enthalpy values of 31.70kJ/mol (Ig-nZVI) and 20.91kJ/mol (nZVI) and standard Gibbs free energy values of -5.92kJ/mol and -7.07kJ/mol for Ig-nZVI and nZVI respectively. Adsorbent produced from leaf extracts of African mango tree (Irvingia gabonensis) and stabilized by iron oxide could be an attractive option for elimination of dye from industrial effluents.

Highlights

Dye industry effluents constitute one of the most challenging wastewaters to be treated for their high chemical oxygen demand (COD), biological oxygen demands (BOD) and reduction in dissolved oxygen (DO) of the water bodies and for the colour they impart on these water bodies (Zawani et al, 2009)
Due to the paucity of data on the leaf, this study explored the potential of employing the use and compare convention iron zerovalent nanoparticle and Irvingia gabonensis stabilized iron (Ig-nZVI) nanocomposites for elimination of methyl red (MR) and methyl orange (MO) in aqueous solution
Dye Used: The dyes used for this work are methyl red (MR) and methyl orange (MO) presented in figure 1a and b respectively

Summary

Introduction

Dyes are principally used in the production of consumer products such as paints, textiles, printing inks, paper, and plastics (Kant, 2012). Rapid industrialization and urban development, have resulted in the generation of large quantities of aqueous effluents, many of which contain high levels of harmful pollutants such as organic dyes (Vijayaraghavan and Yun, 2008, Xu et al, 2013). Chemical agents for the textile industries effluents (Preethi et al, 2006, Meshko et al, 2001; Chen et al, 2001, Purkait et al, 2007; Chen et al, 2011) Adsorbents such as nanocomposites (Adeyemo et al, 2017) and zerovalent metals (Ponder et al, 2000; Lin et al, 2005; Xiong et al, 2007; Wu et al, 2009; Xu et al, 2010; Wang et al, 2010; Liu et al, 2010; Liu and Zhang, 2010) have become important for the removal of heavy metal ions, dyes and other pollutants from aqueous solution. Due to the paucity of data on the leaf, this study explored the potential of employing the use and compare convention iron zerovalent (nZVI) nanoparticle and Irvingia gabonensis stabilized iron (Ig-nZVI) nanocomposites for elimination of methyl red (MR) and methyl orange (MO) in aqueous solution

Methods

Results

Conclusion