Copper-based nanoparticles for the removal of the crystal violet dye via degradation and adsorption: a comparative account

Abstract

Nanoparticles are almost omnipresent with significant pros and cons. Scientists have ventured into environmental nanotechnology, synthesizing unique nanoparticles in the laboratory. Copper nanoparticles are an active area of research for the decontamination of water from toxic dyes in the context of environmental nanotechnology. Copper is an abundant element in our earth's crust. However, rapid aerial oxidation limits its application. The present review article focuses on removing a toxic dye crystal violet (CV) via adsorption and degradation involving copper-based nanoparticles. Various synthetic protocols of such nanoparticles, removal efficiency including reusability, effect of doping and physico-chemical conditions, mechanisms, and connections towards circular economy were summarized here. A comparative account was depicted between adsorption and degradation for the elimination of CV involving copper-based nanoparticles. The current review paper will hopefully be an asset for the industries that release harmful dyes for sustainable water management.

Fig. 1. Flow chart of the different type of dyes.

Scheme 1. Schematic representation of the removal of dye with different catalysts via (A) degradation and (B) adsorption.

Fig. 2. (a) XPS study of Cu NCs-30, (b) Cu NCs-40, and (c) Cu NCs-50 Cu 2P spectra, (d) XRD spectra of CuNCs.

Fig. 3. FE-SEM of Cu NCs synthesized using (a) 30 mL of WGE (b), 40 mL (c), 50 mL (d), and EDAX of Cu NCs-50.

Fig. 4. Schematic representation of copper oxide using wheat grass extract.

Fig. 5. UV-visible photocatalytic degradation profiles of MB in presence of (a) NiFe₂O₄, (b) Cu_xNi_1−xFe₂O₄, (c) Cu_xNi_1−xFe₂O₄/CNTs, and (d) comparative percentage degradation plots of synthetic photocatalyst.

Fig. 6. (a) Photodegradation of crystal violet under varying circumstances (b) degree of disintegration of crystal violet dye across time intervals and (c) kinetics of crystal violet degradation with and without the photocatalyst produced at pH 8.0 under UV-visible light.

Fig. 7. (a) Decrease in intensity, (b) linear plot and (c) mechanism of dye degradation of CuMoO₄ nanostructures.

Fig. 8. Reaction route of crystal violet by the MCOD technique with CuO@AC.

Fig. 9. Theoretical physicochemical properties of before and after degraded dye products.

Fig. 10. Mechanism of degradation between CV and copper nanoparticles.

Fig. 11. Plots of (a) pseudo-first-order and (b) pseudo-second-order kinetic models for CV adsorption onto H₂ and Cu at various starting dye concentrations.

Fig. 12. Comparison between adsorption and degradation for CV removal.

Priyanka Sharma

Supriyo Kar

Mamta Sahu

Mainak Ganguly