Membrane separation processes has become one of the emerging technology which undergo a rapid growth during the past few decades. It has drawn the world attention especially in the separation technology field, one of the chemical engineers' specialty with its distinguish performance compared to the conventional separation technology.

The excellent mass-transfer properties conferred by the hollow fiber configuration soon led to numerous commercial applications in various field such as the medical field (blood fractionation), water reclamation (purification and desalination), gas separation, azeotropic mixture separation (using pervaporation). Others application of this type of membrane are in various stage of development, e.g. and the biochemical industry (bioseparation and bioreactor) and hydrocarbon separation (by pervaporation). Due to the high technology of this advanced materials, Malaysia is urged to focus more in the research of this materials as it has showed its distinguish performance in various field and applications compared to the conventional technique.

Historical Development of Membranes

Table 1 below indicates some of the historical development of the membrane technology before the "Golden Age" of membrane technology:

Table 1: Historical Development of Membranes

Year	Development
1748	Abbe Nollet – water diffuses from dilute to concentrated solution
1846	The first synthetic (or semisynthetic) polymer studied by Schoenbein & produced commercially in 1869.
1855	Fick employed cellulose nitrate membrane in his classic study Ueber Diffusion.
1866	Fick, Traube, artificial membranes (nitrocellulose)
1907	Bechhold, pore size control, "ultrafiltration"
1927	Sartorius Company, membranes available commercially
1945	German scientists, methods for bacterial culturing
1957	USPH, officially accepts membrane procedure
1958	Sourirajan, first success in desalinating water

The "Golden Age" of membrane technology (1960-1980) began in 1960 with the invention by Loeb and Sourirajan of the first asymmetric integrally skinned cellulose acetate RO membrane^,. This development simulated both commercial and academic interest, first in desalination by reverse osmosis, and then in other membrane application and processes. During this period, significant progress was made in virtually every phase of membrane technology: applications, research tools, membrane formation processes, chemical and physical structures, configurations and packaging.

Basic Morphology

Figure 1: Membrane Morphology

Two basic morphology of hollow fiber membrane are isotropic and anisotropic (Figure 1). Membrane separation is achieved by using of this morphologies. The anisotropic configuration is of special value. In the early 1960s, the development of anisotropic membranes exhibiting a dense, ultrathin skin on a porous structure provided a momentum to the progress of membrane separation technology. The semipermeability of the porous morphology is based essentially on the spatial cross-section of the permeating species, ie, small molecules exhibit a higher permeability rate through the fiber wall. While the anisotropic morphology of the dense membrane which exhibit the dense skin, is obtained through the solution-diffusion mechanism. The permeation species chemically interacts with thepolymer matrix and selectively dissolves in it, resulting in diffusive mass transport along the chemical potential gradient, as what demonstrated in the pervaporation process.