Starch/PVA hydrogels for oil/water separation

PVA polymers have been well-known as water-absorbing materials but their brittle nature hinders their applicability. In this study, we enhanced the strength of hydrogel and its water-absorbing capabilities by glutaraldehyde-assisted crosslinking of starch with PVA and blending BMIM-BF4 to enhance the plasticity and generate porosity within the hydrogel multiplying the swelling capacity up to 300% and understand the kinetics and mechanism of water absorption based on the structure of the hydrogel. The ability of starch/PVA hydrogel to selectively adsorb water from oil-water emulsions was determined by establishing the underwater oleophobic nature (oil contact angle similar to 153.6 degrees), subjecting the hydrogel to oil-water emulsion to determine the water absorbed. The hydrogels' biodegradable nature was tested by an efficient in-house biotic system and mechanisms for biodegradation have been discussed. The biodegradability (similar to 90%) was determined for 50% starch in PVA sample in 28 days. These properties observed in the hydrogels will find applications in irrigating arid and semi-arid areas and also in developing super-absorbent hydrogels for hygiene-related product development etc. which can be biodegraded in an economic way.