Development of a fast self-healing hydrogel scaffold with superior mechanical strength and exploring their efficient heavy metal intake capacity

Abstract

Hydrogel is a cross-linked 3D polymer networks that can absorb large amount of water while maintaining its structure due to polymer networks, have gained significant attention because of their attractive applications. Self-healing hydrogels have the capability to heal the cracks autonomously or under the effect of stimuli by reforming all the broken bonds in the material to regain its original shape and properties. However, it seems a challenge to fabricate self-healing hydrogel with superior mechanical properties because they are inversely related. Here a dual cross-linked hydrogel is presented, which was fabricated by the free radical polymerization reaction using acrylic acid, alginic acid and borax introduced as PAA-Alg-B hydrogel. Furthermore, biocompatible and environmentally friendly modified nano cellulose cross-linker (MNCC) was used to improve the mechanical properties of the hydrogel than traditional chemical cross-linker. PAA-Alg-B hydrogel showed an excellent self-healing properties with around 83% healing efficiency within 24 hours due to dynamic borate ester bond and non-covalent hydrogen bond interactions, enabling rapid repair of structural damage and maintaining functional integrity overtime. The hydrogel also demonstrated tunable mechanical toughness (137 kJ/m3) and elongation (1117%). It also has tremendous swelling properties (448 g/g) in water. To assess heavy metal removal capacity of the hydrogel spectrophotometrically, a series of adsorption experiments was done and the result revealed that the maximum adsorption capacity of Cr3+, Ni2+ and Cu2+ was 87.57 mg/g, 114.02 mg/g and 99.42 mg/g, respectively. Kinetic data fitting to theoretical models exhibited adsorption carried out via chemisorption. Thus, synthetic hydrogel can serve as a fantastic, sustainable solution for wastewater treatment.