Enhanced removal of cationic dye by calcium alginate/organobentonite beads: Modeling, kinetics, equilibriums, thermodynamic and reusability studies.

In this study, acid-activated organobentonite (OAB), calcium alginate (A) and calcium alginate/acid-activated organobentonite composite beads (A-OAB) were prepared and applied for the removal of methylene blue from solutions in batch system. The zero point charge of pH (pHpzc), Scanning electron microscopy (SEM) and Fourier transformed infrared spectroscopy (FTIR) analysis were carried out. The effects of pH solution (2-11), temperature (15, 25, 35 and 45°C), initial concentration (20-500mg/L), and contact time were investigated. The adsorption processes fitted well with the pseudo-second-order kinetic model and both models Langmuir and Chapman isotherms. Results showed that the maximum adsorption capacities of (OAB), (A) and (A-OAB) for the adsorption of MB were 263.80, 483.6 and 799.43mg/g at 25°C, respectively. Thermodynamic studies showed spontaneous and endothermic nature of the overall adsorption process. Desorption tests showed that the removal efficiency of MB decreased from 95 to 89.7% after six regeneration cycles for (A-OAB). From this, (A-OAB) can be utilized as an economical adsorbent for the removal of basic dyes from the contaminated waste water.