A statistical study of the effect of preparation conditions on the structure and performance of thin film composite reverse osmosis membranes

Abstract

This work describes a statistical study of the membrane formation reaction between 1,3-phenylene diamine (MPDA) and 1,3,5-benzenetricarbonyl trichloride (TMC) on polysulfone support. The membrane performance has been characterized in terms of water flux, salt passage, and intrinsic salt permeability, and the membranes were also characterized with respect to several structural and morphological factors. The ranges within which the concentration of each monomer was varied were chosen as being relevant to industrial practice, and this is borne out by the fact that the performance of the membranes formed is within the range of practical interest. This analysis reveals that the concentrations of MPDA and TMC significantly influenced the intrinsic salt permeability, water flux, and the characteristic properties of the active polyamide layer. Polynomial models have been derived for the performance parameters using response surface methodology, and allow an identification of monomer concentrations for optimal performance of the membrane.

Keywords:

• Thin film composite
• Response surface methodology
• Polyamide
• Statistical data analysis
• Reverse osmosis
• Membranes’ structure–property

Acknowledgments

The studies were performed as part of a project sponsored by Dow Chemical Company (Project No. 08DOW001). One of the authors (JG) was supported during the course of this study by a Postdoctoral Fellowship of the MHRD. The authors thank the central facilities of IIT Bombay and SAIF, for the AFM and electron microscopy results reported here, and the Fluid Mechanics Lab, Department of Chemical Engineering, IIT Bombay, for the use of profilometer.