Lead and cadmium removal from natural freshwater using mixed activated carbons from cashew and shea nut shells
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ORIGINAL PAPER
Lead and cadmium removal from natural freshwater using mixed activated carbons from cashew and shea nut shells Koffi Pierre Dit Adama N’goran 1,2 & Donourou Diabaté 1 & Koffi Marcellin Yao 2 & N’Guessan Louis Berenger Kouassi 3 & Urbain Paul Gnonsoro 4 & Kacou Charles Kinimo 1 & Albert Trokourey 1 Received: 3 May 2018 / Accepted: 22 August 2018 # Saudi Society for Geosciences 2018
Abstract Biomass wastes are potential low-cost and promising materials for removal of carcinogenic metals in contaminated waters. However, no information is available for cashew and shea nut shells that are abundantly grown in West Africa. We investigated lead and cadmium removal from aqueous solutions using activated carbons prepared from cashew and shea nut shells collected in Côte d’Ivoire, West Africa. The effects of contact time, initial concentration of cadmium(II) and lead(II), pH, and adsorbent mass were examined. The cashew and shea nut shells and their mixture were found to be good sorbents for cadmium and lead at an optimum mass dose of 12 g/L and pH 5.0 in synthetic solution. The adsorption rates varied between 94 and 99% for lead and between 86 and 94% for cadmium. The Langmuir model described isotherm of lead(II) ions adsorbed by shea nut shells, while lead adsorbed by cashew nut shells fitted the Freundlich model. The cadmium adsorption isotherms were described by Freundlich model. The Langmuir model best fitted lead and cadmium adsorptions by the mixture of the two activated carbons. Moreover, lead and cadmium adsorptions followed second-order kinetics. The cashew and shea nut shell activated carbons, and their mixture successfully removed cadmium and lead from natural freshwater. Keywords Heavy metal . Adsorption isotherms . River water decontamination . Côte d’Ivoire
Introduction Chemical pollutants are released into the environment as a result of many sources such as industrial, mining, and agricultural activities (Chakraborty et al. 2015; Kouassi et al. 2015; Toro et al. 2016). Among these chemicals, heavy metals are of great concern due to their toxicity, persistence, and nonbiodegradability (Taiwo and Awomeso 2017; Fonseca et al.
2017). Hence, monitoring heavy metals pollution in the environment is very important. Lead and cadmium are known to be toxic metals with no nutrient values. They are abundant almost everywhere in the nature. They incorporate into the food chain even at low concentrations in water systems, resulting in a wide variety of adverse effects in wildlife and humans (Zhang et al. 2017). Water birds exposure to sub-lethal dose of cadmium and lead
* Koffi Marcellin Yao [email protected] Koffi Pierre Dit Adama N’goran [email protected] Donourou Diabaté [email protected]
Albert Trokourey [email protected] 1
Laboratoire de Chimie Physique, Université Félix Houphouet Boigny, 22 BP 582, Abidjan 22, Côte d’Ivoire
2
Département Environnement, Centre de Recherches Océanologiques (CRO), 29 rue des Pêcheurs, BP V 18, Abidjan, Côte d’Ivoire
3
Université Peleforo Gon C
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