A key property of a membrane is its ability to allow selected components to pass through the membrane, called permselectivity. Differences in the transport rate of various components through the membrane determine the permselectivity. The processes in which membranes are used, can be classified according to the driving force used in the process. The commercially and technically most relevant processes are pressure-driven processes, such as reverse osmosis, ultra- and microfiltration or gas separation; concentration-gradient driven processes, such as dialysis; partial-pressure-driven processes, such as pervaporation; and electrical-potential-driven processes, such as electrolysis and electrodialysis .
I n many areas of the chemical, petrochemical, oil and gas industries today, membrane separations have become standard processes used either as alternatives to or in combination with conventional process steps . Membrane separations can lead to reduced energy consumption, operating costs and investment requirements. However, the overall success of the membrane technology is still lagging behind these expectations. Technical barriers for membranes that prevent them to enter other industries are fouling, instability, low flux, low separation factors, and poor durability.
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