Ni doped zinc oxide nanoparticles supported bentonite clay for photocatalytic degradation of anionic and cationic synthetic dyes in water treatment

In this study, a selective method for removal of dyes from aqueous solutions using nanocomposites of nickel doped zinc oxide nanoparticles (Ni0.02Zn0.98O) photocatalyst supported on bentonite clay was investigated. The nanocomposite was characterized by FTIR, and UV-Vis molecular spectroscopy as well as XRD, SEM and EDX analysis. Congo red (CR), methyl orange (MO) (anionic azo dyes) and crystal violet (CV) (cationic dye) were examined as target dyes. The effects of various parameters such as pH, dosage of adsorbent, contact time, and light illumination on the rate of removal of dyes were investigated and optimized. The results showed significant improvements in the removal of MO, CV, and CR by 90%, 98%, and 93%, respectively, for coupled adsorption and photocatalysis mechanisms with illumination times of 120 min for CR, and 240 min for MO and CV. The photodegradation end products were analyzed by GC-MS to detect the mechanism of decolorization. The kinetics of decolorization by nanocomposites can be well described by the pseudo-first order model. Finally, the proposed method was successfully applied to decolorize the effluent of a textile factory.

Automated summary

This study investigated a method for selectively removing dyes from aqueous solutions using nanocomposites of nickel doped zinc oxide nanoparticles supported on bentonite clay. The nanocomposite exhibited significant improvements in removing various dyes, achieving removal rates of 90% to 98%. The proposed method was successfully applied to decolorize effluents from a textile factory, demonstrating its potential for industrial wastewater treatment.