High Stability Thin Film Composite Reverse Osmosis Membranes
DOE Phase I Contract DE-FG02-05ER84228
Chemical and mechanical stability of state of the art reverse osmosis membranes for water purification are two properties that need significant improvements to provide more economic and robust filtration performance in membrane processing. Stability of current reverse osmosis membranes to strong oxidizers such as chlorine is very poor resulting in high water pre-treatment costs and costly biofouling issues. Commercial membranes are also mechanically delicate resulting in high attrition rates under intermittent use. Membrane filtration costs remain approximately 100-1000 times higher than conventional municipal water and waste-water treatment plants primarily due to low membrane stability.
A new family of polymers that has successfully demonstrated 10-20 times greater chlorine tolerance and superior mechanical stability as thin film composite nanofiltration membranes will be developed during the Phase I and Phase II programs for more demanding reverse osmosis applications. The membrane pore structure will be strategically designed to provide the high salt rejection selectivity required for seawater desalination. Increasing the water permeability, or recovery, is also a key goal of these efforts.
During Phase I a number of selected polymer constituents will be evaluated for their effect on membrane filtration performance such as salt rejection, water permeability and stability. Thin film composite membranes will be fabricated by conventional methods and their performance evaluated using a cross flow filtration apparatus. The best candidate polymer formulations will be fully developed and demonstrated in Phase II resulting in a production-ready technology for licensing.
Successful development of the proposed reverse osmosis membrane technology will provide more reliable and cost-efficient water purification and waste-water treatment. Membrane filtration is convenient and mobile and the ability of reverse osmosis filtration to produce potable water from seawater for a modest price is unequaled. More robust membrane technologies will also benefit a number of industries including chemical, petrochemical, semiconductor, food and dairy, pharmaceutical, and environmental remediation.