Thin-Film Composite Reverse-Osmosis Membranes: Origin, Development, and Recent Advances

Approaches to prepare tfc polyamide membranes by coating diamine during, and/or post formation of asymmetric membranes and their performances

“…Cadotte's significant work was with thin film composite membranes (Cadotte, 1977;Cadotte et al, 1981, Petersen, 1993 based on preparation of asymmetric polysulfone membranes and the coating of crosslinked polyamide via interfacial polymerization on them (Morgan, 1965). The crosslinked polyamide formation was carried out using 1,3-phenylene diamine and trimesoyl chloride.…”

Evaluation of Military Field-Water Quality. Volume 7. Performance Evaluation of the 600-GPH Reverse Osmosis Water Purification Unit (ROWPU): reverse Osmosis (RO) Components

“…In an early study, Riley Lt al. 4 2 reported a value of n of -0.01 for a UOP PA-300 membrane exposed to seawater at a temperature of 25 0 C arid a pressure of 990 psig for 500 h. A similar test performed with clean water for 200 h at 556C and a pressure of 390 psig yielded an n of -0.012,…”

“…ir which i -the number of moles of fors produced with the complete dissociation of one mole of the salt, 0 is an osmotic coefficient that corrects for the nonideal behavior of the electrolyte, m -the molality of the salt, and RT -the product of the ideal gas constant and the absolute temperature, Values of * at 25°C and molalities ranging from 0.001 to 6 are given in Appendix A (Table A-1) for the slts NaCi, KCI, MgCl 2 , CaCl 2 , Na 2 SO 4 , MgSO 4 , and a mix of sodium and magnesium sulfates. 15 -2 0 Values of 0 for temperatures other than 25°C may be obtained from the references given in the table.…”

“…4 1 The concensus is that membrane compression has little or no effect on salt rejection, although not much has been published on this topic. 4 1 If the salt rejection is constant with time, Eq. 16 shows that the ratio B/U must also be constant with timt, or…”

“…Low water flux and compaction under sustained high pressure were the main problems. 4 In 1966, Cadotte used polysulfone in the substructure. Polysulfone increased the resistance to compaction so that fluxes could be increased to 10 to 15 galJ(d # ft 2 CA) with cellulose-acetate (CA) membrane was used in the prototype RO unit, Two of these elements were placed in series in a single pressure vessel, Six such pressure vessels were then arranged in a 3-2-1 step-down series designed to give a 60% product-water recovery with fresh water.…”