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Kinetic study was applied for sodium bentonite (Na-B) and hexadecylpyridinium bentonite (HDP-B) under different amounts, namely 50% (50HDP-B), 100% (100HDP-B), and 200% (200HDP-B) with respect to cation exchange capacity (CEC). Pseudo first-order and pseudo second-order kinetic models were performedto optimize the sorption ofCongo red (CR) dye from aqueous solution. The experimental data fit the pseudo second order kinetic model well. The sorption capacity ([q.sub.e]) of CR dye by the organo-bentonites at equilibrium was 36.0 mg [g.sup.-1] (72.1%) for 50HDP-B, 48.05 mg [g.sup.-1] (96.1%) for 100HDP-B, and 49.2 mg [g.sup.-1] (98.4%) for 200HDP-B. These results were considerably higher than that found by Na-B. Response surface methodology with threevariable, three-level Box-Behnken design was applied for 100HDP-B to describe the removal of CR dye. The effects of three variables, namely temperature, adsorbent dosage, and initial dye concentration, were studied. Predicted values of adsorption efficiency were found to be in good agreement with the obtained experimental values ([R.sup.2] = 0.97). A second-order polynomial model successfully described the effects of independent variables on the CR dye removal. At the optimized condition, the toxic azo dye could be quantitatively removed from aqueous solution. The results of the present study suggest that the organobentonite can be used as an efficient sorbent for dye removal from aqueous solution. Key words: organo-bentonite, Congo red dye, kinetics study, Box-Behnken design. Resume : Nous avons mene une etude cinetique sur la bentonite sodique (Na-B) et des bentonites modifiees par l'hexadecylpyridinium (HDP-B) de differentes compositions, soit 50 % (50HDP-B), 100 % (100HDP-B) et 200 % (200HDP-B), afin d'examiner leur capacite d'echange cationique (CEC). Nous avons utilise les modeles cinetiques de pseudo-premier ordre et de pseudo-second ordre pour optimiser la sorption du colorant azoique rouge Congo (RC) en solution aqueuse. Les donnees experimentales concordaient tres bien avec le modele cinetique de pseudo-second ordre. La capacite de sorption ([q.sub.e]) du RC par les organobentonites a l'equilibre etait de 36,0 mg [g.sup.-1] (72,1 %) pour la 50HDP-B, de 48,05 mg [g.sup.-1] (96,1 %) pour la 100HDP-B et de 49,2 mg [g.sup.-1] (98,4 %) pour la 200HDP-B. Ces resultats etaient considerablement plus eleves que ceux observes pour la Na-B. Nous avons applique la methode des surfaces de reponse couplee a un plan de Box-Behnken a trois facteurs et a trois niveaux pour decrire l'elimination du colorant RC par la 100HDP-B. Pour ce faire, nous avons etudie les effets de trois variables, soit la temperature, la quantite d'adsorbant et la concentration initiale de colorant. Nous avons constate une bonne concordance entre les valeurs calculees de l'efficacite d'adsorption et les valeurs experimentales ([R.sup.2] = 0,97). Un modele polynomial de second ordre permet de decrire adequatement les effets des variables independantes sur l'elimination du colorant RC. En conditions optimisees, ce colorant azoique toxique peut etre elimine quantitativement d'une solution aqueuse. Les resultats de la presente etude permettent de penser que cette organobentonite peut etre utilisee comme sorbant pour l'elimination efficace de colorants en solutions aqueuses. [Traduit par la Redaction] Mots-cles : organobentonite, colorant rouge Congo, etude cinetique, methode de Box-Behnken., Introduction The use of synthetic dyes in the food, pharmaceutical, cosmetics, textiles, paper, dyeing, and plastics industry has been growing since the beginning of the century, favoring the emergence of [...]

The present study focuses on investigating the adsorption characteristics of anionic Congo Red (CR) and Indigo Carmine (IC) dyes using hexadecyltrimethyl ammonium bromide‐modified Bentonite (HDTMA‐Bentonite) with varying loading amounts. The removal effectiveness of anionic dyes was examined as a function of the HDTMA+ loaded amount, contact time, initial concentration, and adsorbent dosage. The XRD data revealed that the interlayer spacing of Bentonite increased from 1.42 to 1.98 nm. The FTIR approach was used to analyze the surface modification of hybrid Bentonite; however, the hydrophobic nature of hybrid Bentonite was confirmed by ATG measurements. A kinetic investigation of sorption was done. The results demonstrated that the pseudo‐second‐order model fitted the adsorption kinetic data better than the pseudo‐first‐order rate equation, and that the amount of HDTMA+ loaded affects the adsorption capacity. According to the Weber‐Morris intra‐particle diffusion equation, the CR and IC dyes diffused faster as the amount of added cationic surfactant rose from 0 % to 100 % of the CEC value. Temkin and Langmuir equation is found to best represent the equilibrium data for two dye‐HDTMA‐B systems. Hybrid Bentonite was regenerated by NaOH, and reused without a significant decrease in its sorption efficiency, supporting the prosperity of its utilization as an effective adsorbent against toxic dyes from wastewater. [ABSTRACT FROM AUTHOR]