Rational Synthesis, Characterization, and Application of Environmentally?Friendly (Polymer?Carbon Dot) Hybrid Composite Film for Fast and Efficient UV Assisted Cd2+ Removal from Water

Abstract

Carbon-dots (CDs) are of particular interest in numerous applications. However, their efficiency for heavy metal removal from wastewater was not yet reported. Herein, we rationally synthesized CDs from petroleum-coke-waste via hydrothermal treatment in the presence of ammonia.This drove the formation of outstanding photoluminescent, water-soluble, biocompatible, and high yield of monodispersed sub-5 nm CDs. The CDs are co-doped with high 10 % of N and 0.2 % of S. The as-prepared CDs possess unprecedented photoluminescent properties over broad pH range making these dots unique efficient pH sensor. chitosan (CH)-CDs hybrid hydrogel nanocomposite film were further prepared as a platform membrane for the removal Cd2+ metal from wastewater. The as prepared CH-CDs menbranes show a relatively good mechanical properties, based on stress-resistant and flexibility in order to facilitate handling. The equilibrium state was reached within 5 minutes. Intriguingly, the UV-light illuminations enhanced the Cd2+ removal efficiency of the photoluminescent CDs substantially by four times faster under. It was found that adsorption followed pseudo-second-order kinetic and Langmuir isotherm models. The maximum adsorption capacity at 25? C was found to be 112.4 mg g-1 at pH 8. This work paves the way to new applications of CDs in water treatment.