Orange peel as low-cost adsorbent in the elimination of Cd(II) ion: kinetics, isotherm, thermodynamic and optimization evaluations

Temilade Fola Akinhanmi,Abideen Idowu Adeogun,Peter Aina,Edwin Andrew Ofudje,Ilo Mayowa Joseph

doi:10.1186/s40643-020-00320-y

Temilade Fola Akinhanmi, Abideen Idowu Adeogun + Show 3 more

Open Access

https://doi.org/10.1186/s40643-020-00320-y

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Abstract

The presence of heavy metals in polluted water is known not only to cause severe harm to marine organisms, but also to terrestrial plants and animals including human beings. This research applied low-cost and environmentally benign adsorbent primed from waste orange peel (OP) for the removal of Cd(II) ions from aqueous solution via batch adsorption process. The surface properties of the orange peel powder were studied using scanning electron microscopy (SEM), X-ray spectroscopy (XRD) and Fourier transform infrared spectroscopy (FT-IR). Operational conditions like temperature, contact time, sorbent dosage, solution pH and initial adsorbate concentration were investigated. The utmost uptake of Cd(II) ion was obtained at a contact time of 120 min, initial metal concentration of 240 mg/L, adsorbent dosage of 0.04 g/L, temperature of 45 °C and solution pH of 5.5. Equilibrium results showed that the orange peel adsorbent has an adsorption capacity of 128.23 mg/g as obtained from the Langmuir isotherm. The adsorption kinetics data followed a pseudo-first-order kinetic model with correlation coefficient (R2) > 0.9 and low standard % error values. The adsorption process was found to be endothermic in nature with enthalpy of 0.0046 kJ mol−1 and entropy of-636.865 Jmol−1K−1. Results from the optimization study indicated that higher adsorbent dosage and lower Cd(II) ion concentration increased the percentage of Cd(II) ion removal. Thus, orange peel could be used in the removal of Cd(II) ion from aqueous solutions.

Highlights

IntroductionIndustrialization and urbanization, massive volume of sewage sludge is being produced in the urban areas of major countries of the world (Riaz et al 2018)
With the rapid development, industrialization and urbanization, massive volume of sewage sludge is being produced in the urban areas of major countries of the world (Riaz et al 2018)
It is principally poisonous to kidney causing bone demineralization while excessive exposures to cadmium could damage the proper function of the lung and increase the chance of lung cancer (Bernard, 2008)

Summary

Introduction

Industrialization and urbanization, massive volume of sewage sludge is being produced in the urban areas of major countries of the world (Riaz et al 2018). The search for various adsorbents with excellent adsorption properties has been the focus of some researchers in the last decades Several adsorbents such as bone meal-derived apatite (Ofudje et al 2020), fish scale (Adeogun et al 2018), olive cake (Doyurum and Celik 2006), black gram husk (Saeed et al 2005), kraft lignin (Mohan et al 2006), tea-industry waste (Cay et al 2004), bagasse-derived activated carbon (Mohan and Singh, 2002) and activated carbon from Filtrasorb (Kapoor et al 1999) have been reported for their ability to eradicate cadmium ions in polluted waste water. With the rapid increase in population and an upsurge in demand for oranges, waste generation from orange peel is on the increase and this is worrisome

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