Mohamed Osman Awaleh , Youssouf Djibril Soubaneh , Leila Farah Adawe , Alexandre Coulombe , Mohamed Abdillahi Robleh , Moussa Mahdi Ahmed , Nima Moussa Egueh , Omar Assowe Dabar , Mahamoud Ali Chirdon , Ibrahim Houssein Kadieh
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引用次数: 0
Abstract
The aim of this study was to evaluate the potential use of the two biggest clay deposits from the Djibouti region as raw material for wastewater treatment and for the production of ceramics. The present study is the first to investigate the kinetics, sorption isotherms, hysteresis of Cu and Cd on two clays from the East African Rift System (EARS). Djiboutian clays (DCs) were characterized by a rapid uptake of these heavy metals with an equilibrium time of 400 min and uptake ranging from 48.8% to 97.4% at high initial metal concentrations (15 mg L−1) in the medium. A high adsorption coefficient (kdS) values, from 8.31 to 20.80 L g−1, were observed for Cu, indicating a strong affinity of this metal for both clays. The kdS values for Cd (0.29–3.64 L g−1) were significantly lower, suggesting different interaction mechanisms. These results are consistent with the Freundlich constant (kf) values obtained for Cu (8.88–1.05 mg g−1(L·mg−1)1/n) and Cd (0.80–1.05 mg g−1(L·mg−1)1/n) sorption isotherms onto DCs clays. Furthermore, desorption process exhibited high hysteresis index (HI) values (2.18–2.33) for Cu, suggesting strong sequestration on both DCs. These sorption behaviors can be associated with the properties of both Djiboutian clays whose characterization revealed large specific surface areas (62.7–64.8 m3/g), high open porosity (44.4–51.2%), and the presence of organic matter and negatively charged clay minerals such as illite, which interact well with divalent metals. Characterization of both clays and the chemical data of DCs plotted on a ternary diagram (SiO2− Al2O3−other oxides) suggested that these clays can be applied as raw materials for structural ceramic products. The study underscores the potential of DCs for trapping Cu and Cd pollutants from wastewater and for producing Class BIIb ceramics.
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Physics and Chemistry of the Earth is an international interdisciplinary journal for the rapid publication of collections of refereed communications in separate thematic issues, either stemming from scientific meetings, or, especially compiled for the occasion. There is no restriction on the length of articles published in the journal. Physics and Chemistry of the Earth incorporates the separate Parts A, B and C which existed until the end of 2001.
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