Polyamide synthesis for reverse osmosis membrane and substrate optimization

Abstract

Because of growing population, global warming and increasing industrialisation, our need for clean water is growing. Water treatment systems can be used to treat industrial wastewater, sewage, etc., as well as sea water, and turn it into drinking water. There are many systems for purifying water. Nanofiltration, microfiltration, reverse osmosis, forward osmosis, and electrodialysis are the most common. 60% of the world's water purification systems are RO. In addition, the use of polymer membrane is common. In general, the RO membranes work under the press, which is able to change the pressure from 60 bar up to 100 bar. Reducing energy consumption is the most issue in RO research due to the high pressure. The cost of RO systems can be reduced by reducing the amount of pressure applied. When the amount of pressure applied is reduced, cost effectiveness is achieved. Reverse osmosis is the process by which water is desalinated using membranes that separate the dissolved components in the feed water but allow the water to pass through. In the reverse osmosis membrane process, as water passes through a membrane by the solution-diffusion mechanism, solutes are retained by electrostatic forces in their size and dissolved ions on the membrane surface. Polymeric RO is composed of three layers. The firs layer, a thin film, which is made up of polyamide separates the components like salt ions. The second layer, a porous polysulfone support layer, directs the flow of water. The final layer, a nonwoven PET layer, increases mechanical strength. Polysulfone carrier layers can be produced by electroblowing, electrospinning or solution blowing. The support layer produced by nanofiber production methods generally has a more porous structure. The nanofiber support layer leads to useful way by which the water flux conveniently pass through, contrast to other support layer types. This results in a high water flow and a reduction in the required applied pressure. This situation reduced energy concuption. The supporting layers made by the phase inversion method have a low percentage of the surface voidand the void size on the surface is relatively small compared to the others support layer types made by nanofiber production methods. The advantage of the phase inversion method is that is more suitable for industrial production. The reasons for the selection of nanofiber production by electro-blow spinning method are that the fiber optimization process is relatively easier and it is also efficient in mass production.