Preparation of PASP/PVA degradable semi-interpenetrating hydrogels and their application in oil-water separation and heavy metal ion adsorption

Hydrogels have attracted significant attention due to their high hydrophilicity and low viscosity. However, the poor mechanical properties of most hydrogels have limited their applications. By incorporating a semi-interpenetrating polymer network (semi-IPN) into polyaspartic acid (PASP)/polyvinyl alcohol (PVA) hydrogels, both physical and chemical cross-linking have enhanced the mechanical properties of the hydrogels. The stainless steel mesh coated with the hydrogel exhibits super hydrophilicity and underwater super oleophobicity (the underwater oil contact angle is approximately 157°), and can stably separate oil-water mixtures in various oil phases and complex environments (acidic, alkaline, and saline). The removal efficiency remains above 98% even after 20 cycles of separation. Furthermore, the PASP/PVA semi-IPN hydrogel can effectively adsorb copper ions, and the hydrogel is biodegradable in the environment after use. These results demonstrate that the PASP/PVA semi-IPN hydrogel has promising prospects in wastewater treatment.