Studies on electrochemical characterization and performance prediction of cellulose acetate and Zeocarb-225 composite membranes in aqueous NaCl solutions

We have mixed cellulose acetate and Zeocarb-225 in different ratios, leading to the preparations of Membrane-1 and Membrane-2. Membrane potential, water content, and conductance measurements have been carried out to estimate and analyze the data in terms of equilibria and important electrochemical parameters. The Donnan equilibrium has been incorporated to estimate the activity coefficient of counterions, ypM, and solute, y±M in the membrane phase along with the parameter, so called ϕ   expressing non-ideality. Dependence of the extent of hydrophilicity of both membranes on mean electrolyte concentrations has been examined. Selectivity in membranes is discussed in terms of dissociation equilibria, Kds and Kdf. It has been found that membrane surface charge density σs increases with increasing of external NaCl concentration. Dependence of water transport number and cationic transport number on electrolyte concentration shows a similar trend of variation. At higher mean concentration of electrolyte, water transport number in Membrane-2 has a negative value. Membrane-2 has a higher value of water transport number than Membrane-1. The entropy production due to solute and water transport has been quantified for both the membranes in the light of nonequilibrium thermodynamics. The various type of interactions such as solute–membrane, solute–water, and water–membrane are analyzed in terms of friction coefficients (fijfij) of Spiegler's frictional pore model. In our case, an fwm

Graphical abstractCo-mixing is an effective method for membrane modification. Cellulose acetate and Zeocarb-225 were mixed in different ratios giving rise Membrane-1 and Membrane-2 with distinct performances. The former had constant [dtM+/dCmean] value and later had distinguishable change as shown in the representative figure. In Membrane-2, the rejection was increased. (○) Membrane-1; (▵) Membrane-2.Figure optionsDownload full-size imageDownload high-quality image (27 K)Download as PowerPoint slide