NANOLAYER POLYMERIC COATINGS TO ENHANCE THE PERFORMANCE AND SERVICE LIFE OF INORGANIC MEMBRANES FOR HIGH TEMPERATURE-HIGH PRESSURE BIOMASS PRETREATMENT AND OTHER APPLICATIONS

Membrane technology has become increasingly attractive in several applications including water filtration, food industry, oil and gas, and biomedical applications. Most recently the quest for renewable, bioenergy has called for use of membranes in biomass pretreatment and other stages of producing biofuel. The success and advancement of the membrane technology for these various applications has, however, been impeded by the fouling of membranes, which causes the pores in the microporous structure to block, resulting in reduced efficiency, and in some cases, total failure of the membranes system. This challenge leads to a tremendous increase in the cost of using membranes as a separation tool, thus making it uneconomical and therefore inaccessible for many applications that could have taken advantage of this technology.

Whereas most of the researchers have concentrated their work on post fouling techniques, i.e. techniques to clean the membrane after fouling, in this research, an approach was taken to apply a protective ultrathin coating on the membrane’s surface. A high temperature stable, and chemically and mechanically robust polymer, polyetherimide (Ultem) was applied on nanoporous membranes using a solution-based coating method. The main objective was to demonstrate the potential success of nanoporous inorganic membranes to perform organic separations with high throughput at high temperatures up to 250 ⁰C and operating pressures up to 550 psi. The high temperature stable polymer coating will be able to protect the membrane pores to prevent pore fouling during the separation process.

The results have shown that the polyetherimide - Ultem 1010 grade produced by Sabic Innovation Company, when processed into the desired polymer solution for dip coating allows the formation of very thin layer polymer on the surface of the membrane. The Nanolayer polymer coating is chemically resistant to caustic attacks and other acidic environments. The relationships between polymer concentration and the coating thickness and properties were analyzed and the coating process and parameters have been optimized to give the best coating conditions. Although there is a slight reduction in the pore size of the coated membrane, the results have demonstrated that the membrane lifetime, performance, and overall separation characteristics is significantly improved