Assessment of Untreated Coffee Wastes for the Removal of Chromium (VI) from Aqueous Medium

Abstract

Industrial discharges loaded with heavy metals present several problems for aquatic ecosystems and human health. In this context, the present study aims to evaluate the potential of raw spent coffee grounds to remove chromium from an aqueous medium. A structural and textural study of coffee grounds was carried out by FTIR, XRD, and TGA analysis. The optimum conditions for the removal of Cr(VI), for a solution with an initial concentration of 100 mg/l, were adsorbent dose 2.5 g/l, pH 4.0, and contact time 90 min. The adsorption equilibrium results show that the Langmuir isotherm best describes the process with an adsorption capacity of 42.9 mg/g and that the adsorption kinetics follows the pseudosecond-order model. The calculated thermodynamic parameters showed that the adsorption is exothermic and spontaneous. The activation energy value (Ea) indicated that the retention is physisorptive in nature. The regeneration of the adsorbent was carried out by three eluents, among which HCl was the best. Finally, a brief cost estimation showed the great potential of coffee grounds as a low-cost adsorbent.

Biomass-Derived Adsorbents for Dye and Heavy Metal Removal from Wastewater

“…The capacity of several agricultural waste materials, such as almond shells (AS), walnut shells (WS), peanut shells (PS), and coconut shells (CS) to eliminate Cr 6+ from water at room temperature and acidic pH utilising batch mode was studied [45]. While the adsorption of Cr 6+ was adequately characterised by Langmuir model, the walnut shell provided higher adsorption yield and maximal monolayer capacity, which was found to be 37.5 mg g -1 .…”

Adsorptive performances and valorization of green synthesized biochar–based activated carbon from banana peel and corn cob composites for the abatement of Cr(VI) from synthetic solutions: Parameters, isotherms, and remediation studies

“…In this work, the interaction mechanism between biochar adsorbent and metal solutions were assessed by utilizing Freundlich and Langmuir's adsorption isotherm models [ 51 ]. According to the Langmuir isotherm, the biochar adsorbent's surface contains uniform sites for monolayer adsorption [ 52 , 53 ].…”