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Magnetic alginate/rice husk (m-ALG/RH) bio-composite beads prepared with ionotropic gelation method and used for methylene blue (MB) removal. Structural analysis of magnetic alginate/rice husk composite beads was performed using FTIR, SEM-EDS and TGA techniques. The accomplishment of magnetic alginate/rice husk composite beads as an adsorbent for the removal methylene blue was investigated from aqueous solution. Maximum experimental adsorption capacity of the bio-composite beads was calculated as 274.9 mg/g. The various process parameters such as pH, temperature and initial MB concentration optimized. It was determined that pH no significant effect on dye removal efficiency of beads while temperature and ionic strength caused a decrease on removal efficiency. The various isotherm models were applied for determine the adsorption mechanism and Freundlich isotherm model is more compatible with the experimental data. The kinetic studies showed that the adsorption of methylene blue can be well described by the fractal Brouers-Sotolongo kinetic model. The thermodynamic calculations indicated that methylene blue adsorption was a spontaneous and exothermic nature. The results showed that the magnetic alginate/rice husk bio-composite as low-cost and eco-friendly adsorbent can be effectively used for cationic dye removal steps in the environmental engineering applications.

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This study presents a detailed comparison of the two most popular fractal theories used in the field of kinetics sorption of pollutants in porous materials: the Brouers-Sotolongo model family of kinetics based on the BurrXII statistical distribution and the fractional kinetics based on the Riemann-Liouville fractional derivative theory. Using the experimental kinetics data of several studies published recently, it can be concluded that, although these two models both yield very similar results, the Brouers-Sotolongo model is easier to use due to its simpler formal expression and because it enjoys all the properties of a well-known family of distribution functions. We use the opportunity of this study to comment on the information, in particular, the sorption strength, the half-life time, and the time dependent rate, which can be drawn from a complete analysis of measured kinetics using a fractal model. This is of importance to characterize and classify sorbent-sorbate couples for practical applications. Finally, a generalization form of the Brouers-Sotolongo equation is presented by introducing a time dependent fractal exponent. This improvement, which has a physical meaning, is necessary in some cases to obtain a good fit of the experimental data.

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The main purpose of this work is to study the effect of a new process of accelerating which consist to couple the electrochemical process with the adsorption to remove an anionic dye, the indigo carmine. That is why, we investigated the effects of the new process of accelerating the adsorption process by using alternating current (AC) on the retention of an anionic dye, the indigo carmine. The adsorption capacity of dye (mg/g) was raised with the raise of current voltage in solution, temperature, and initial indigo carmine concentration and decreased with the increase of initial solution pH, current density, and mass of carbon. The results demonstrate that the removal efficiency of 97.0 % with the current voltage of 15 V is achieved at a current density of 0.014 A/cm2, of pH 2 using zinc as electrodes and contact time of 210 min for adsorption in the presence of AC. Concerning the adsorption without AC, the results obtained showed that for an initial concentration equal to 20 mg/L, more than 95 % amount of adsorbed dye was retained after 405 min of contact in batch system. The comparison between adsorption in the presence and absence of an alternating current shows the importance of the alternating current in the acceleration of the adsorption method and improve the performances of FILTRASORB 200. For both cases, the adsorption mechanism follows the fractal kinetics BSf(n,α) model and the Brouers-Sotolongo isotherm model provides a good fit of the experimental data for both adsorption with and without alternating current.

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In this study, the kinetic data of the adsorption of two antibiotics onto three nanoadsorbents was modeled using the Brouers-Sotolongo fractal model. The model parameters were calculated at different initial antibiotic concentrations using various approximations of the kinetic equation for two quantities of practical relevance: the sorption power and the half-time characteristic of the sorption. The merits of the nanomaterial were then compared in terms of their application in the elimination of dangerous antibiotic wastes. We also developed a formula to calculate the effective rate of the best adsorbent. This study presents the modeling method in detail and has a pedagogical value for similar researches.

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