Removal of a Binary Dye Mixture of Congo Red and Malachite Green From Aqueous Solutions Using a Bentonite Adsorbent

Abstract

An important application of clay is as a solid adsorbent for industrial dyes. The aim of the present work was to carry out an experimental—theoretical study of the adsorption of dye mixtures, namely malachite green (MG) and Congo red (CR), by bentonite. Adsorption studies were conducted after evaluation of the impact of several parameters, including pH, adsorbate dose, and contact time, on the removal of MG and CR. The pH of the dye solution is strongly affected by the chemistry of both the dye molecules and of the adsorbent in an aqueous solution. Where both dye molecules exist in solution, the optimum pH was found to be 8.2 in order to achieve the maximum adsorption of both MG and CR. Preliminary studies showed that 60 min of contact time is sufficient to reach adsorption equilibrium. The adsorption studies were carried out using 1.0 g samples of bentonite. The amount of dye adsorbed was found by application of classical least squares to the synthetic dye mixtures. Data from equilibrium adsorption on bentonite were analyzed by Freundlich, Langmuir, Redlich-Peterson, and Temkin isotherm equations using regression analysis for non-linear forms of those equations. For binary-mixture analysis, isotherm parameters were determined from single-component adsorption studies and the theoretical amount of dye adsorbed was calculated using an extended Langmuir isotherm. Non-linear error analysis showed that the Temkin and Redlich-Peterson isotherms gave the best fits to the equilibrium data for adsorptive removal of MG and CR by bentonite.

Cationic Dye (Methylene Blue) Removal from Aqueous Solution by Montmorillonite

“…The use of cheep adsorbents for the removal of color from its aqueous solution will provide as a potential alternate to the conventional treatment techniques. Recent investigations by several researchers proved onto use of low-cost, reusable, locally available, biodegradable adsorbent made from natural sources like peat, 6 29,30 are being considered as alternative low-cost adsorbents. A large variety of non-conventional adsorbent materials have been also proposed and studied for their ability to remove dyes.…”

Brilliant green dye adsorption onto composite snail shell–rice husk: Adsorption isotherm, kinetic, mechanistic, and thermodynamics analysis

“…As shown in the table in Exhibit , the K RP , a RP , and β RP values were 63.7292 (L/g), 7.0104 (L/mg), and 0.5905, respectively. The value of β RP indicates that the Redlich–Peterson isotherm model tends away from the Langmuir isotherm model and also makes the system heterogeneous (Özdemir & Keskin, ). A previous study reported a similar result (Tosun, ).…”

Removal of Toluidine Blue and Safranin O from Single and Binary Solutions Using Zeolite

“…The sorption of CR and malachite green (MG), a cationic dye, by bentonite, whose CEC was 1.35 meq/g, was tested from single and binary solutions with sorption capacities of about 200 and 170 mmol/g for CR and MG [17]. In the mixed dye, the molar ratio of CR/MG was 0.52, with the capacities about 90 and 100 mmol/g for CR and MG sorption [17].…”