Cellulose dialysis membrane containing raw clinoptilolite enhances the removal of Rhodamine 6G from aqueous solutions

In this work, we studied the adsorption of Rhodamine 6G (R6G) using a simple removal system consisting of a raw natural zeolite, clinoptilolite (CLI) packed within a cellulose membrane. The structural, composition and thermal properties of CLI were characterized by X-ray diffraction (XRD), energy dispersive X-ray analysis (EDX) and thermal analysis (TG/DTG, HF-DSC). The results revealed that the natural zeolite consisted of a crystalline phase of calcium clinoptilolite (CLI) from the monoclinic system with Si/Al ratio of similar to 4.33, with high thermal stability. Besides, textural characterization obtained with the Brunauer-Emmett-Teller (BET) technique showed a relatively large specific surface area of 17.4 m(2)/g and the Barrett-Joyner-Halenda (BJH) described the pore size distribution of CLI. The adsorption studies were carried out by immersing the CLI-membrane system into R6G solutions with various concentrations (C-0 = 32, 47, 94, 168 mg/L), at 25 degrees C. The cellulose membrane facilitated the mobility of R6G molecules by enhancing their removal from the solution and allowed the easy recovery of the contaminated zeolite after the experiment. The adsorption equilibrium was suitably represented by nonlinear Liu model with an adsorption capacity of 8.7 mg R6G/g CLI. The nonlinear kinetics were described by Mixed-order and Elovich models at low and high R6G concentrations, respectively. In addition, diffusional nonlinear models confirm the participation of various diffusional mechanisms during the adsorption of R6G. Our approach showed its potential for the adsorption of R6G and can be further applied in the treatment of wastewater contaminated with dyes, pesticides, ions, and dangerous molecules generated either by the industry or at the laboratory level.