Hyperbranched polyurethane/reduced carbon dot-zinc oxide nanocomposite-mediated solar-assisted photocatalytic degradation of organic contaminant: An approach towards environmental remediation

Photocatalysis has carved out a niche in the recent times, as an environmentally benign, renewable and innovative technology for degradation of common organic pollutants in nature. The present work focuses on the development of a sustainable hyperbranched polyurethane (HPU) nanocomposite with reduced carbon dot-zinc oxide nanohybrid (RCD-ZnO) as a prospective solar energy-assisted heterogeneous photocatalyst for degradation of anionic surfactant contaminants. RCD-ZnO nanohybrid was synthesized by a simple and eco-friendly protocol by employing Colocasia esculenta leaf extract as bio-reductant, and fabricated with a starch-based HPU by an in situ polymerization process. Structural characterizations were performed by FT-IR, UV-Visible, EDX, TEM, TGA and DSC techniques. Optical studies revealed optical band gap of RCD-ZnO (2.12 eV) was reduced considerably in comparison to bare RCD (3.18 eV) and ZnO (3.3 eV). The RCD-ZnO nanohybrid-reinforced HPU nano-composite displayed significant enhancement in mechanical properties like strength (1.9 folds), elongation (1.39 folds), scratch hardness (1.53 folds), toughness (3.54 folds) over pristine HPU as well as improved thermal stability (25 degrees C enhancement). Furthermore, the RCD-ZnO nanohybrid-reinforced HPU nanocomposite demonstrated high efficiency as a heterogeneous recyclable photocatalyst for degradation of aqueous surfactant contaminants, dodecylbenzenesulfonate (96.7% in 110 min) and commercial detergent (94.8% in 150 min) upon exposure to sunlight, following the pseudo-first order kinetics model. Thus, the current work holds good potential for the development of such high performance sustainable nanocomposite as an efficient solar energy-assisted heterogeneous recyclable photocatalyst for large scale applications.