Adsorption of Cadmium, Copper and Chromium by an Agricultural Soil Impacted by Mining Activities Alseno K. Mosai & Elisee N. Bakatula & Hlanganani Tutu Received: 10 April 2017 /Accepted: 12 July 2017 # Springer International Publishing AG 2017 Abstract Batch adsorption studies for cadmium (Cd), copper (Cu) and chromium (Cr) onto an agricultural soil impacted by mining activities were conducted in single- and multi-component systems. The effect of initial con- centration, pH and competing ions (Fe 3+ , Ca 2+ , Co 2+ , Mg 2+ ,K + , Ni 2+ and Zn 2+ ) on adsorption was studied. The soil exhibited high adsorption capacities for the elements at all initial concentrations with the adsorption process better described by the Freundlich isotherm. Adsorption was found to proceed via an ion exchange mechanism. The pseudo second-order kinetic model described the adsorption of the elements (R 2 > 0.999), indicating a chemisorption process. The adsorption of Cd increased with pH in both systems while that for Cu decreased. The adsorption of Cr decreased with pH in the single-component system, but increased in the multi- component system. The adsorption of Cd was affected more by competing ions while Cu and Cr were not significantly affected (p > 0.05). Elemental speciation under varying conditions was studied using the PHREEQC geochemical modelling code. The observed high capacity of the soil for the elements pointed to the soil’ s potential as a repository, a feature that would change depending on the speciation of the elements and soil conditions. Keywords Agricultural soil . Adsorption capacity . Cadmium . Copper . Chromium 1 Introduction Environmental pollution due to waste from mining in- dustries and agrochemicals has been increasing for years (Mattikalli and Richards 1996; Pehlivan et al. 2009). This waste contains pollutants such as cadmium, copper, chromium, arsenic, mercury, lead and zinc among others (Gaur and Adholeya 2004). The soil, air and water have been negatively affected directly or indirectly in most instances as a result of waste disposal (Setyorini et al. 2002). Vegetation, livestock and human beings are also negatively affected as they depend on these natural resources. The soil is the main disposal site for elemen- tal waste whereas air and water are mainly affected indirectly (Tanji and Valoppi 1989; Kirpichtchikova et al. 2006). Soils in or near mining areas are prone to contamination by elemental waste due to direct and indirect contact. Elements in soils can reach the ground- water where they can accumulate at high concentrations, increasing risks to public health since some are carcino- genic (e.g. cadmium, chromium and arsenic) and can lead to abnormalities in morphology, high mortality and mutagenic effects in humans when ingested (Pier and Bang 1980; McLaughlin et al. 2000; Scheren et al. Water Air Soil Pollut (2017) 228:287 DOI 10.1007/s11270-017-3487-1 A. K. Mosai : H. Tutu (*) Molecular Sciences Institute, School of Chemistry, University of the Witwatersrand, Private Bag X3, WITS, Johannesburg 2050, South Africa e-mail: hlanganani.tutu@wits.ac.za E. N. Bakatula Civil, Geological and Mining Engineering Department, Université de Montréal—École Polytechnique de Montréal, Montréal, QC, Canada