Use of Lignite as a Low-Cost Material for Cadmium and Copper Removal from Aqueous Solutions: Assessment of Adsorption Characteristics and Exploration of Involved Mechanisms

Abstract

Lignite, as an available and low-cost material, was tested for cadmium (Cd) and copper (Cu) removal from aqueous solutions under various static experimental conditions. Experimental results showed that the removal efficiency of both metals was improved by increasing their initial concentrations, adsorbent dosage and aqueous pH values. The adsorption kinetic was very rapid for Cd since about 78% of the totally adsorbed amounts were removed after a contact time of only 1 min. For Cd and Cu, the kinetic and isothermal data were well fitted with pseudo-second order and Freundlich models, respectively, which suggests that Cd/Cu removal by lignite occurs heterogeneously on multilayers surfaces. The maximum Langmuir’s adsorption capacities of Cd and Cu were assessed to 38.0 and 21.4 mg g−1 and are relatively important compared to some other lignites and raw natural materials. Results of proximate, scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDS), Fourier transform infrared spectroscopy (FTIR) and X-Ray diffraction (XRD) showed that the removal of these metals occurs most likely through a combination of cation exchange and complexation with specific functional groups. The relatively high adsorption capacity of the used lignite promotes its future use as a low cost material for Cd and Cu removal from effluents, and possibly for other heavy metals or groups of pollutants.

Competitive bio-sorption of basic dyes onto petiole palm tree wastes in single and binary systems

“…The PSO model exhibited the highest average calculated R 2 (0.979) and the lowest APE (5.33%) (Table 3). This result suggests that the dyes removal by PTW might mainly a chemical process including complexation with the adsorbent functional groups and cation exchange [63,64]. Similar results were reported in various research studies, namely the adsorption of methylene blue and crystal violet by palm kernel fiber [65] and the adsorption of Dye Basic Blue 41 and Basic Yellow 28 by activated carbon [66].…”

Industrial dye removal from tannery wastewater by using biochar produced from tannery fleshing waste: a road to circular economy

“…First order Second order From Table 3, it could be clearly noted that the correlation coefficients calculated for both pseudo-firstorder and pseudo-second-order models were relatively high, indicating a good fit to the experimental data [44]. However, the calculated amounts of removed SFR dye at equilibrium (q e,I ) for all the tested biochars by the pseudo-first-order model were very low compared to the experimental ones and the related APE was important, presuming that SFR dye removal kinetics is not a pseudo-first-order process.…”

Dynamic experiment on the treatment of acidic chromium-containing wastewater by lignite loaded nano FeS

“…Therefore, it is often used as an efficient and low-cost adsorption material in environmental treatment. Jellali et al 18 studied the removal capacity of lignite for Cd 2+ and Cu 2+ in water. The results show that the saturated adsorption capacity of lignite for Cd 2+ and Cu 2+ can reach 38.0 mg g −1 and 21.4 mg g −1 .…”