Improvement adsorption capacity of methylene blue onto modified Tamazert kaolin

Abstract

In this study, three adsorbents were prepared with the raw kaolin issued from the Tamazert region in Algeria (Tamazert kaolin (KT)), for the removal of basic dye methylene blue (MB) from aqueous solutions. The first absorbent, KT-1, was obtained by thermal treatment; the second, KT-2, was obtained by thermal followed by acid treatment; and the third, KT-3, was obtained by thermal followed by acid and alkaline treatments. These adsorbents were characterized by powder X ray diffraction, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller surface area, and scanning electron microscopy. Adsorption equilibrium isotherms of MB were correlated with common isotherm equations such as Langmuir and Freundlich models. The modified kaolins (KT-1, KT-2, and KT-3) showed different capacities of the equilibrium adsorption in comparison with raw kaolin (KT). The maximal adsorption capacity (111 mg g À1 ) was observed with modified kaolin (KT-3). The effect of operating parameters such as the initial dye concentration, contact time, adsorbent dose, pH, and temperature were studied onto KT-3. The removal of MB by adsorbent increased with an increase in adsorbent dose and initial concentration. Kinetics models, the pseudo-first-order, and pseudo-second-order rate equations were applied. The obtained results show that the adsorption of MB by KT-3 was well described by the pseudo-second-order kinetic model. The thermodynamic study revealed that the adsorption process was spontaneous, endothermic, and the positive value of ÁS indicated the affinity of MB molecules to the adsorbent surface. This study showed that this new adsorbent could be a good candidate for some activated carbons.

Adsorption of methylene blue onto natural Saudi Red Clay: isotherms, kinetics and thermodynamic studies

“…As shown in figure 5, there is a very sharp increase in the adsorption efficiency below 0.2 g but reaches almost a plateau from 0.2 g onwards and the increase in removal efficiency is very small. These results are in good agreement with the observation reported by [34] for kaolin, [35] for red mud, [22] for zeolite and [36] for natural clay.…”

“…Pseudo-first-order model did not fit well with the experimental data ( figure 11(a)) while pseudo-second-order kinetic model fitted very well with R 2 values very close to unity (R 2 >0.999) as shown in figure 11(b). Kinetic model results reveal that the adsorption of MB dye onto SRC could be better explained by pseudo-second-order kinetic model which is in good agreement with the work of [27] for kaolin, [34] for Algerian kaolin and [35] for activated red mud. The results are summarized in table 3.…”

Effective removal of nitrate ions from aqueous solution using new clays: Tamazert kaolin treated under microwave irradiation

“…The results showed that the adsorption system followed the pseudo-second-order model, with correlation coefficient value of 0.99 (for the tow adsorbent) which is better than the pseudo-first-order-model (0.67 for KH + and 0.42 for K-lime) and the calculated qe, value from this model is also in good agreement with the experimental value q e,exp . These results indicate that the adsorption of nitrate on KH + and on K-lime could be better explained based on the pseudo-second-order kinetics model [22,38].…”

“…After the acid treatment ( Fig. 2), the interlayer cations are replaced by protons and the octahedral cations are dissolved [22][23][24].…”

“…The Fig. 14 represent Intraparticle diffusion model for the adsorption of nitrate on the tow modified kaolin. The first sharper portion is the instantaneous adsorption or external surface adsorption; the second portion is the gradual adsorption stage where the intraparticle diffusion is the rate limiting; and the third portion is the final equilibrium [22].…”