Abstract
The aim of this study is the valorization of the Moroccan clays (QC-MC and QC-MT) from the Middle Atlas region as adsorbents for the treatment of water contaminated by cadmium Cd (II) ions. The physicochemical properties of natural clays are characterized by ICP-MS, XRD, FTIR, and SEM techniques. The adsorption process is investigated as a function of adsorbent mass, solution pH, contact time, temperature, and initial Cd (II) ion concentration. The kinetic investigation shows that the adsorption equilibrium of Cd (II) ions by both natural clays is reached after 30 min for QC-MT and 45 min for QC-MC and fits well to a pseudo-second-order kinetic model. The isotherm study is best fitted by a Freundlich model, with the maximum adsorption capacity determined by the linear form of the Freundlich isotherm being 4.23 mg/g for QC-MC and 5.85 mg/g for QC-MT at 25°C. The cadmium adsorption process was thermodynamically spontaneous and exothermic. The regeneration process showed that these natural clays had excellent recycling capacity. Characterization of the Moroccan natural clays before and after the adsorption process through FTIR, SEM, XRD, and EDX techniques confirmed the Cd (II) ion adsorption on the surfaces of both natural clay adsorbents. Overall, the high adsorption capacity of both natural clays for Cd (II) ions removal compared to other adsorbents motioned in the literature indicated that these two natural adsorbents are excellent candidates for heavy metal removal from aqueous environments.
Highlights
Cadmium is selected as a highly toxic inorganic pollutant to the environment or other living organisms. e environmental problem of cadmium is a consequence created by a human through their activities such as alloy in the automotive industry; as a pigment; as a stabilizer for plastics, in battery manufacturing, and nuclear reactors [1,2,3]
Numerous studies have developed several treatment processes to reduce the amount of cadmium in aquatic environments [7,8,9,10,11]. e adsorption process is a better advantage rather the other methods due to their simplicity, low cost, and efficiency in removal of contaminants of a different nature in particular heavy metals [12, 13]
We studied the performance of cadmium adsorption selected as an inorganic pollutant. e removal of cadmium using QC-MC and QC-MT was carried out by varying several parameters such as adsorbent mass, pH of the solution, initial concentration of cadmium, contact time, and temperature. e kinetic, isotherm, and thermodynamic studies were investigated. e regeneration study was examined by using different acids
Summary
Cadmium is selected as a highly toxic inorganic pollutant to the environment or other living organisms. e environmental problem of cadmium is a consequence created by a human through their activities such as alloy in the automotive industry; as a pigment; as a stabilizer for plastics, in battery manufacturing, and nuclear reactors [1,2,3]. Cadmium is selected as a highly toxic inorganic pollutant to the environment or other living organisms. Considering the toxicity and adverse effects of cadmium on human health, the World Health Organization (WHO) fixed the maximum concentration of cadmium in drinking water at 0.03 mg/L [6]. Numerous studies have developed several treatment processes to reduce the amount of cadmium in aquatic environments [7,8,9,10,11]. Journal of Chemistry adsorbents which are abundant, economically profitable, and efficient for the treatment of ecosystems is a great challenge. In this context, the application of natural clay minerals is of great scientific interest. The application of natural clay minerals is of great scientific interest. e adsorption of different pollutant by clays minerals has three types: the first is physical and nonionic adsorption, the second is ion exchange with electrostatic interaction and exchange reaction, and the third is zeolite action [14,15,16,17]
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