Membrane Structure

The chemical design and physical construction of membranes are very important considerations in balancing the functions of membranes. The structural design of a high-performance membrane depends on the development of advanced membrane materials, membrane surface modification and the membrane preparation method. In a membrane permeation process, the chemical composition and the physical structure of the membrane can both be important factors. This chapter focuses on the different types of membranes: symmetric, asymmetric, and composite membranes. Membranes having large pores are called ‘porous membranes’ typically used in ultrafiltration (UF) and microfiltration applications, whereas membranes having extremely small pores, such as molecular gaps between polymer chains based on thermal vibrations of polymer, are called ‘non-porous’ membranes’. The chapter also presents a summary of the preparation conditions on the structure of the polymer membrane. The structures of liquid membranes are classified into three categories: bulk, emulsion and supported types.