Lanthanum (III) incorporated chitosan-montmorillonite composite as flexible material for adsorptive removal of azo dyes from water

Abstract

La (III) incorporated chitosan-montmorillonite (CS-La3+-MMT) composite was prepared and characterized using FTIR, XRD, TGA, EDX and SEM analysis. The surface area, pore volume and the pore size distribution of the CS-La3+-MMT were calculated using the BET technique. The dye adsorption efficiency of the composite was evaluated using an aqueous solution of (50 mg/L) reactive red (RR) and acid orange (AO) dyes. The extent of adsorption in initial pH value of the solution, contact time, and initial concentration of dye were also investigated. The optimal conditions for removal of dyes were found to be: Molar ratio of (CS-La3+-MMT), 1:1; pH: 4; temperature: 30 C for 40 min in 50.00 mL of 50 mg L 1 of dye solutions and 100 mg of adsorbent. The results indicated that the adsorption capacity of the CS-La3+-MMT composite was higher than the average values of those of CS, MMT, La3+ and CS/MMT. The isotherms of the adsorption process were also examined. The adsorption process were in good agreement with the Langmuir adsorption isotherm model fitting. The highest sorption efficiency of RR and AO dyes on the CS-La3+-MMT was attributed to the highly porous nature of the composite in addition to their ability to form hydrogen bond between free AOH groups present in the composites with the dye molecules.