Porous Polysulfone Diaphragm As Separator In Electrochemical Processes
Electrochemical processes are widely used for production of various chemicals. When the process is carried out in chemically hostile conditions, a special separator is required to separate catholyte and anolyte solutions. The Porous Polysulfone Diaphragms reinforced with non-woven support fabric for use as separator in electrochemical processes involving highly acidic solutions. These diaphragms have very high porosity (60-70%) with submicron pore sizes resulting in low electrical resistance in electrolyte solutions and are stable up to 30% H2SO4 solution. The production cost of these diaphragms is lower by an order of magnitude compared to presently used Nafion membranes with comparable properties.
The polysulfone diaphragm can be used as a separator in electrolytic cell for production of various chemicals such as ammonium per sulphate (NH4)2S2O8 by electrochemical process in acidic medium.
The process of manufacturing porous polysulfone diaphragm consists of preparation of a casting solution using optimum quantities of polysulfone polymer, selected additives and appropriate solvent followed by coating of this solution over a non-woven polyester support fabric and then gelling it in water to produce a polysylfone-nonwoven fabric support integrated film (diaphragm). The film is annealed in boiling water to remove traces of additives and solvent before use.
All the chemicals (polymer, additives and solvent) are manufactured in country and are available in local market. Non-woven polyester support is an imported item, but available with local suppliers.
As the entire process is manual in nature (for diaphragm size 105 cm x 38 cm or smaller) no extensive infrastructure is needed except an air-conditioned room (~ 15 m2area) with relative humidity < 40% is required during operation. The material cost for 1 m2 diaphragm is estimated to be about Rs.1250/-.
One chemist and two technicians are adequate to prepare the diaphragms of above stated sizes.