Recent Advances in Adsorption Kinetic Models: Their Application to Dye Types

This study investigates the possibility of applying an adsorption process using two abundant natural minerals M1 and M2. Without pretreatment or activation, the adsorbents were used to treat real textile wastewater samples (collected from Fez city, Morocco). As a cost-effective alternative, these materials were characterized by different analyses, including X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and X-ray fluorescence (XRF). Chemical oxygen demand (COD) and biological oxygen demand (BOD) were used to characterize the textile wastewater. Additionally, the influence of operating conditions (contact time, adsorbent dosages, and pH) was evaluated. Results show that the adsorption process takes place quickly, reaching the equilibrium at 90 and 160 min for M1 (88% COD) and M2 (79% COD). Both materials show a higher affinity to Cr (39%) and lower affinity to Cu (28%). A pseudo-second-order kinetic model provides the best fit to the experimental adsorption data. Germination tests indicate a low toxicity after the adsorption process. Performance of both materials was compared with that of other literature studies.

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Adsorption Studies on the Removal of Textile Effluent over Two Natural Eco-Friendly Adsorbents

The environment and human health protection as well as the search for promising and cost-effective materials to eliminate hazardous dyes are a main contemporary worldwide challenge. In this regard, improving the morphology and the specific surface area of the oil shale ash leading to highly efficient innovative adsorbent for the removal of Crystal Violet (CV) and Methyl orange (MeO) dyes. In this research work, we prepared and characterized the treated oil shale ash (TOSA) adsorbent through XRD, XRF, FTIR, pHpzc, SEM-EDX, TEM, and BET. The chosen material’s selectivity and sensitivity depend on the pH and the foreign ions' strength due to the competition between different charges present in the colored solution. The adsorption capacities of CV and MeO, under conditions of dye concentration 100 mg L−1 with adsorbent dose 0.5 g L−1, are 168.88 mg g−1 and 72.26 mg g−1 respectively. Furthermore, a monolayer pattern could be assigned to the Langmuir adsorption model and the equilibrium kinetics of adsorption is best approved by the pseudo-second-order model for the two dyes. According to response surface methodology, the experimental values for CV and MeO were consistent with the predicted values that lead to the maximum dye removal rate of 99.98% and 67.13% respectively. The regeneration results confirm the performance of our adsorbent after several adsorption-desorption cycles. The capital cost of the treated materials used for adsorption was estimated to be around $ 2.15 for 1 g which means that is a non-expensive process for the future valorization of natural resources.

Highly-efficient treated oil shale ash adsorbent for toxic dyes removal: Kinetics, isotherms, regeneration, cost analysis and optimization by experimental design

The Fast-Efficient Adsorption Process of the Toxic Dye onto Shells Powders of Walnut and Peanut: Experiments, Equilibrium, Thermodynamic, and Regeneration Studies

This research aims to assess the employability of fava bean peels (FBP) as low-cost adsorbents in the removal of Brilliant Green (BG) and Eriochrome Black T (EBT) from aqueous solutions and therefore in colored wastewater treatment. Scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), and pHPZC were used to characterize these materials. The constants of Langmuir, Freundlich, and Dubinin-Radushkevich have all been determined. The adsorption capacity of BG and EBT was 28.14 and 7.91 mg g–1, respectively, at 5 g L–1 FBP dose, 40 mg L–1 initial dye concentration, temperature 20°C, and contact time BG (80 min) and EBT (40 min). The calculated thermodynamic parameters indicated that adsorption of BG was endothermic and exothermic for EBT. The isotherm studies show that the adsorption experimental data of both dyes are fitted well by the Freundlich isotherm model. The adsorption of the two dyes studied on fava bean peels is perfectly described by a pseudo-second-order kinetic model. Cyclic experiments have indicated that the current bio-adsorbent can be effectively reused to remove BG and EBT from aqueous solutions. Removal efficiencies remained above 84% and 10% for BG and EBT respectively even after four adsorption–desorption cycles. As a consequence of these relevant results, our inexpensive and environmentally friendly material could provide enormous application prospects in large-scale wastewater treatment in the industrial level.

Assessment of Brilliant Green and Eriochrome Black T dyes adsorption onto fava bean peels: kinetics, isotherms and regeneration study

This study makes it possible to prove that an inexpensive material, namely the residue of grenadine bark extraction (GB), can be used to remove a dye from the textile industry, in particular methylene blue (MB). For this reason, different techniques of characterization of the GB adsorbent have been used such as: scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and the zero charge point. On the other hand, batch studies have been used to evaluate the effect of initial concentration, contact time, adsorbent dose, pH and temperature on the variation in uptake capacity. In this case, the results show that a very fast adsorption kinetics reaching 98% within the first 10 minutes. Additionally, kinetic studies of dye on MB carried out the pseudo-second order at different dye concentration values. Besides, the Langmuir model describes satisfactory adsorption on the GB. Further, thermodynamic studies have indicated that dye adsorption process by grenadine bark (GB) was spontaneous, physisorption and endothermic in naturel

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Studies of the adsorption kinetics process for removal of methylene blue dye by residue of grenadine bark extraction

The aim of this study is to find an effective and inexpensive natural material used as an adsorbent for the textile dyes removal. Indeed, we have been interested in testing the effectiveness of sugarcane bagasse (SB) as a biosorbent to remove brilliant green (BG) and eriochrome black T (EBT). In our experiments, different parameters such as initial dye concentration, contact time, adsorbent dose and solution temperature have been analyzed in a batch system. Similarly, the studies of thermodynamic, kinetic and adsorption isotherm have been evaluated. The sugarcane bagasse (SB) without any modification has been characterized by Fourier transform infrared spectroscopy (FTIR) and scanning electron microscopy (SEM). The maximum adsorption capacity of BG and EBT on the SB adsorbent has been 37.58 and 12.30 mg.g -1 respectively, for a concentration of 40mg.g -1 at a temperature of 20°C and 1g.L -1 of adsorbent. The results of the adsorption kinetics have proved that the pseudo-second order model correctly describes the adsorption phenomenon of the two dyes studied. The Langmuir and Freundlich isotherms have been applied to experimental equilibrium data. The various thermodynamic parameters such as Gibbs free energy (ΔG°), enthalpy (ΔH°) and standard entropy (ΔS°) have indicated that the adsorption is spontaneous and endothermic in brilliant green and exothermic in eriochrome black T.

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Kinetic and thermodynamicstudy of the adsorption of twodyes:brilliant green and eriochrome black T using a natural adsorbent "sugarcane bagasse".

Promising catalyst of cooper impregnated on natural material (CT) synthesized via wet impregnation method, in order to enhance the catalytic wet peroxide oxidation during the degradation of organic matter in a batch reactor under mild conditions. Three different percentages of copper metal (2.5, 5 and 7.5 %) incorporated into CT material which are referred as follows 2.5% Cu-CT, 5% Cu-CT and 7.5% Cu-CT were investigated in the oxidation catalytic of methyl green (MG) dye. The chemical composition, the morphology and the structure of raw CT and all prepared samples, were investigated by X-ray fluorescence, Fourier transform infrared spectroscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM) to get a better understand concerning the catalytic activity behavior of Cu-CT catalyst. Different variable examined the catalytic activity of the samples obtained such as initial concentrations of dye, copper (Cu) loading, temperature and H 2 O 2 effect was investigated to enhance the MG conversion. CWPO experiments showed that 2.5% Cu-CT catalysts have the maximum catalytic activity during the degradation of MG dye. The presence of copper on CT support ameliorates the hydroxyl radicals in the reaction medium after the contact with H 2 O 2 thus enhanced the catalytic conversion of the CT pristine. The optimum conditions showing an important catalytic conversion of MG dye (95 %) at 2.5% of copper loading, 139.10 -3 mol.L -1 H 2 O 2, temperature of 40 °C and at pH 6.0 during  30 min as a reaction time.

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A. El Badraoui

Papers

Studies of the adsorption kinetics process for removal of methylene blue dye by residue of grenadine bark extraction

Kinetic and thermodynamicstudy of the adsorption of twodyes:brilliant green and eriochrome black T using a natural adsorbent "sugarcane bagasse".

Copper-impregnated on natural material as promising catalysts for the wet hydrogen peroxide catalytic oxidation of Methyl Green