Responsive Ultrafiltration Membranes Composed of Cellulose Acetate With N-lsopropylacrylamide (NIPAAm) and Superparamagnetic Iron Oxide (SPIO) Nanoparticles

摘要

Membrane fouling occurs when there is reversible or irreversible attachment of macrosolutes present in the water to the membrane surface. Membrane replacements due to fouling can add significantly to the operating costs of the membrane system. Reversible fouling can be minimized by crossflow operation, backflushing during filtration and/or by chemical pretreatment, but it may take time and energy and as well as have to meet safety guidelines with respect to chemicals used. On the other hand, irreversible fouling cannot be corrected by backflushing or crossflow filtration, and it results into permanent flux decline. Among irreversible foulants, natural organic matter (NOM) is considered to be a major contributor. NOM is composed of wide range of hydrophilic and hydrophobic components; hence, any static hydrophobic or hydrophilic membrane can get fouled. Therefore, a dynamic membrane able to alternate between being hydrophobic and hydrophilic is hypothesized to decrease fouling. Stimuli-sensitive polymers have been gaining attention in recent years due to their unique property that the polymer changes its conformation from a coiled and hydrophobic state to an uncoiled (or globular) and hydrophilic state in the presence of a stimulus. The stimulus can be pH, temperature, ionic strength or electric or magnetic fields. By alternating between the phases membrane surface can be made dynamic.