Adsorptive removal of anionic azo dyes from effluent water using Zr(IV) encapsulated carboxymethyl cellulose-montmorillonite composite

Abstract

The metal incorporated bio-polymers and clay particle composites have been widely used for water/wastewater purification. Since these materials preserve the entire existing features of each component and at the same time, the metal imprinting will enhance the efficiency of adsorption of such composites. Herein, Zr(IV) encapsulated carboxymethyl cellulose-montmorillonite (Zr-CMC-MMT) composite matrix was fabricated and utilized for the removal of aqueous solution of Reactive red 2 (RR) and Acid orange 7 (AO) dyes. The Zr-CMC-MMT composite was characterized using FTIR, XRD, TGA, EDAX, SEM analytical techniques. The surface area, pore volume and the pore size distribution of the Zr-CMC-MMT composite were calculated using the BET isotherm technique. The optimal conditions for adsorption of dyes were found to be; molar ratio of Zr-CS-CMC, 1:1, pH: 3, and temparature: 303 K for 50 mL of 50 mg/L dye solutions. The entire process of dye removal was completed within 40 min. for 100 mg of the Zr-CMC-MMT adsorbent. The isotherms of the adsorption process were in good agreement with the Freundlich model fitting which indicates the heterogeneous surface interaction. Thermodynamic studies suggested that the adsorption process was spontaneous and endothermic in nature. The highly porous nature, electrostatic attraction of the composite, ability to form hydrogen bond between free –OH groups present in the composites, and surface complexation of the composite with the dye molecules enhance the adsorption process.

Keywords

• Acid orange
• Carboxymethyl cellulose
• Montmorillonite
• Reactive red
• Zirconium