Degradation of Congo red dye using ternary metal selenide-chitosan microspheres as robust and reusable catalysts

Abstract

Water pollution is a threatening environmental concern these days, which requires serious attention. Water is contaminated by the heavy discharge of industrial effluents containing organic wastes. Herein, this research work focused on the demand for overcoming water pollution utilizing clean and renewable energy (solar light irradiations) sources for photocatalytic degradation of Congo red (CR) dye with the help of ternary metal selenide-chitosan microspheres (ZBiSe-CM). First, zinc–bismuth-selenide nanoparticles (ZBiSe-NPs) were successfully synthesized via the solvothermal process and then supported with chitosan to prevent leaching of the catalyst. SEM micrographs showed the average size of newly synthesized nanocomposites catalysts was 30.9 nm. The average size of the ZBiSe-CM microspheres was calculated as 812 um with a spherical shape and a porous surface. The presence of prominent peaks in the EDX spectrum for bismuth, selenium, and zinc confirmed the synthesis of the nanoparticles. XRD analysis demonstrated the calculated crystallite size of ZBiSe-NPs was 27.04 nm. The photocatalytic behavior of the catalyst was studied at optimized experimental conditions. The ZBiSe-NPs showed high photocatalytic degradation efficiency (up to 99.63%) for 40 ppm concentration of CR at catalyst dosage 0.225 g, pH 8.0, and temperature 36–38 °C for 2 h of solar light illumination. Photodegradation of CR dye in the presence of ZBiSe-CM follows pseudo-first-order kinetics and the ZBiSe-CM degraded CR dye in five consecutive cycles with high decontamination efficiency. The newly synthesized ternary metal selenide-chitosan microspheres could be used for the decontamination of dyes from industrial wastewater. • New ternary metal selenide-chitosan microspheres were synthesized. • Structural and morphological characteristics of ZBSe-CM were scrutinized. • Highly efficient photocatalytic degradation of carcinogenic Congo red dye. • Factors influencing the degradation phenomena are investigated.