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Item Mass transfer processes in the adsorption of Lead (Pb2+) by apricot stone activated carbon (ASAC) : isotherms modeling and thermodynamic study(Springer, 2021) Abbas, MoussaIn the present study, batch experiments were carried out to elucidate the potential of apricot stone activated carbon ASAC to remove Pb2+ ions from aqueous solution. ASAC was characterized by Bruanauer, Emmett and Teller surface area S = 80.08 (m2/g), Fourier transform infrared spectroscopy and scanning electron microscopy. The effects of various process parameters such as initial pH (2–14), adsorbent dose (5–45 g/L) initial metal ion concentration (20–0 mg/L), contact time (0–90 min), agitation speed (100–700 rpm) and temperature (298–323 k) were investigated in their respective range and their optimum conditions were ascertained. The adsorption kinetics were analyzed by the pseudo-first-order, pseudo-second-order, Elovich and intraparticle diffusion kinetic models. It was found that the adsorption of the metal ions followed pseudo-second-order kinetic model. The Adsorption isotherms were modeled with Langmuir, Freundlich, Temkin, Hasley and Harkins models and their isotherm constants were calculated. The Freundlich model fits the data with a monolayer adsorption capacity of 166.813 mg/g at pH 8. The thermodynamic parameters such as the Gibbs free energy, enthalpy and entropy were calculated to predict the nature of adsorption process. The calculated thermodynamic parameters showed that the adsorption of Pb2+ ions on ASAC is endothermic (ΔH0 = 121.38 kJ/mol) and not spontaneous (ΔG0 > 0) in natureItem Removal of toxic methyl green (Mg) in aqueous solutions by apricot stone activated carbon – equilibrium and isotherms modeling(Taylor & Francis, 2018) Abbas, Moussa; Aksil, Tounsia; Trari, MohamedApricot stone activated carbon (ASAC), was powdered, activated and to be used as effective adsor-bent to remove the dyes from aqueous solutions through batch experiments under operational factors namely, pH, contact time, adsorbent dose, initial dyes concentration and temperature. The physico-chemical, morphological and structural properties of the adsorbents were characterized by scan-ning electron microscope (SEM) and X-ray diffraction (XRD) instruments. Different kinetic modelsindicated that the adsorption is well described by the pseudo-second order model. The isotherms of methyl green (MG) adsorption on ASAC were obtained and correlated with various models. The smaller RMSE values for the Langmuir and Dubinin-Radushkevic models indicated the best fitting; the mono layer adsorption capacity of MG was found to be 148.478 mg g–1 at 21°C and 88.11 mg g–1 at 46°C at pH 10. The thermodynamic functions showed spontaneous and endothermic MG adsorption. In conclusion, the adsorbent prepared from apricot stone (ASAC) was found to very effective and suitable adsorbent for reactive dyes removal from aquatic environment, due to its simple and cheap preparation, easy availability and good adsorption capacity.
