Experimental Study of Water and Salt Fluxes through Reverse Osmosis Membranes

Abstract

Water flux and salt rejection rate, which are the two most important parameters in evaluating the performance of a reverse osmosis membrane process, are desirable to be directly related to the membrane properties and operating conditions. However, the membrane transport theories in their general forms are unable to describe the membrane performance satisfactorily. In this study, water and salt fluxes through reverse osmosis membranes were carefully examined with a cross-flow filtration cell under various operating conditions. Experimental results showed that a notable permeate flux was detected when the driving pressure was smaller than the feed osmotic pressure. Water flux increased with the driving pressure nonlinearly before approaching a linear relation with the pressure. In addition, salt transport was highly dependent on both operating pressure and feed salt concentration. A power relationship between salt flux and concentration was correlated well with the experimental data. The equations for water and salt fluxes obtained from this work would provide a facile and accurate means for predicting the membrane performance in design and optimization of reverse osmosis processes.

Zeolite-filled microporous mixed matrix (ZeoTIPS) membranes: Prediction of gas separation performance

“…Typical applications include gas separations (such as O 2 /N 2 and CH 4 /CO 2 ), the removal of organics and salts from water by reverse osmosis, and the separation of ethanol and water by pervaporation. Numerous polymer membranes have been used to varying degrees of success for these separations [1][2][3][4]; however, more refined size separations remain the goal of considerable ongoing research [5][6][7].…”

Predicting Permeate Fluxes and Rejection Rates in Reverse Osmosis and Tight‐Nanofiltration Processes

“…The need for good estimations of the membrane-solute transport parameters becomes even more evident when comparing simulations to the experiments of Zhou and Song [10], as presented in Fig. 4 a.…”

“…Although the typical trends of permeate flux versus pressure previously discussed are described by the model and good agreement is found for pure water and very low feed concentration (0.1 kg m -3 ), differences higher than ±10 % are found for higher feed concentrations (1 and 10 kg m -3 ) and pressures. In fact, the authors in [10] neglected concentration polarization in the determination of the solute permeability. These inaccuracies will be especially important when analyzing the rejection rates in Sect.…”

Pre-desalination with electro-membranes for SWRO

“…The permeability of a typical SWRO membrane is 3.9×10 -12 m/s.Pa [15]. We assume therefore the following irreversible losses associated with water transport through the membranes:…”