Adsorption of Cr(VI) ions onto goethite, activated carbon and their composite: kinetic and thermodynamic studies
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ORIGINAL ARTICLE
Adsorption of Cr(VI) ions onto goethite, activated carbon and their composite: kinetic and thermodynamic studies G. B. Adebayo1 · H. I. Adegoke2 · Sidiq Fauzeeyat1 Received: 25 September 2019 / Accepted: 24 August 2020 / Published online: 7 September 2020 © The Author(s) 2020
Abstract Hexavalent chromium was adsorbed from aqueous solution with three prepared and characterized adsorbents, namely goethite (G), activated carbon (AC) and their composite (GAC). The goethite particle was synthesized using the precipitation methods, and activated carbon was prepared from the stem bark of Daniellia oliveri tree and composite in a ratio of 1:5 goethite–activated carbon. The adsorption capacities of G, AC and GAC for Cr(VI) are 6.627, 5.455 and 6.354 mg/g with 0.02 g adsorbent within contact time of 60, 180 and 30 min for G, AC and GAC, respectively, for Cr(VI) adsorption at optimum pH of 3. The isotherm studied was best explained by Langmuir adsorption isotherm and fitted with the pseudo-second-order kinetic model. Desorption studies showed that 1.0 M HNO3 was a better desorbing agent than 0.1 M HNO3, 0.1 M HCl and 1.0 M HCl. Chromium was most desorbed (94.60% in Cr//G using 1 M H NO3). The result obtained revealed that goethite and activated carbon produced are favourable adsorbents and the composite of the two adsorbents gives a more favourable, economical and affordable adsorbent for the clean-up of heavy metal contamination. Keywords Adsorption · Thermodynamic · Kinetics · Goethite · Activated carbon · Composite
Introduction The level of contamination of water bodies by textile, steel, paints and electroplating industries is on the alarming rate in developing countries all over the world due to rapid industrialization. High concentration of metal ions has been connected to birth defects, cancer of the digestive tract and lungs, skin lesions, retardation leading to disabilities, liver and kidney damage, and a lot of serious health effect (Jain et al. 2009). It is of utmost importance to make efforts to reduce the wastewater generation in order to provide clean water that meets our teeming population needs (Franca et al. 2015). In the search for ways of tackling these environmental issues, numerous techniques available in this concern have been reported (Zouboulis et al. 2009; Punzi et al. 2015; Asghar et al. 2015). These methods include deposition, * H. I. Adegoke [email protected] 1
Department of Industrial Chemistry, University of Ilorin, P.M.B. 1515, Ilorin, Nigeria
Department of Chemistry, University of Ilorin, P.M.B. 1515, Ilorin, Nigeria
2
chemical precipitation, biological treatment, advanced oxidation process, evaporation, ion exchange, reverse osmosis, electrodeposition, solvent extraction, use of adsorbents and phytoextraction. A number of listed factors affect efficiency of the processes, and adsorption has demonstrated to be an effective technique. Most of these methods have some imperfections such as high cost of operation, high required investment and disposal
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