Chitosan-capped ternary metal selenide nanocatalysts for efficient degradation of Congo red dye in sunlight irradiation.

Wastewater emerging from the industries containing organic pollutants is a severe threat to humans' health and aquatic life. Therefore, the degradation of highly poisonous organic dye pollutants is necessary to ensure public health and environmental protection. To tackle this problem, visible-light-driven ternary metal selenide nanocomposites were synthesized successfully by the solvothermal method and supported by chitosan microspheres (FeNiSe-CHM). The prepared nanoparticles were capped in chitosan microspheres to avoid leaching and facilitate easy recovery of the catalyst. FTIR spectrum confirmed the synthesis of nanocomposite and nanocomposite-chitosan microspheres (FeNiSe-CHM). Based on the SEM images, the nanomaterial and FeNiSe-CHM has an average particle size of 64 nm and 874 µm, respectively. The presence of iron, nickel and selenium elements in the EDX spectrum revealed the synthesis of FeNiSe-NPs. XRD analysis determined the crystallite structure of nanocomposites as 14.2 nm. The photocatalyst has a crystalline structure and narrow bandgap of 2.09 eV. Moreover, the as-synthesized FeNiSe-CHM were employed for the photodegradation of carcinogenic and mutagenic Congo red dye. The catalyst microspheres showed efficient photocatalytic degradation efficiency of up to 99% for Congo red dye under the optimized conditions of 140 min, pH 6.0, dye concentration 60 ppm and catalyst dose of 0.2 g in the presence of sunlight irradiation following the second-order kinetics. After five consecutive cycles, it showed a slight loss in the degradation efficiency. In conclusion, the results demonstrate a high potential of chitosan-based ternary metal selenide nanocomposites for abatement of dye pollutants from the industrial wastewater.

Regenerable chitosan-bismuth cobalt selenide hybrid microspheres for mitigation of organic pollutants in an aqueous environment.

Degradation of hazardous organic pollutants like dyes by semiconducting materials has been considered as one of the dynamic solutions for wastewater treatment. Herein, novel bismuth cobalt selenide (BCSN) tri-composite nanoparticles were prepared with a crystalline structure and narrow bandgap of (2.48 eV). The prepared nanoparticles were embedded in chitosan microspheres to avoid leaching and ensure the easy recovery of the composite. FTIR studies confirmed the synthesis of nanoparticles and chitosan­bismuth cobalt selenide hybrid microspheres (BCSN-CM). SEM images showed the smooth face morphology having an average nanoparticles size of 30 nm and an average microspheres size of 734 µm. The crystallite size of the nanoparticles was also verified using the XRD technique and found to be 21.3 nm by applying Scherer's equation. EDX result demonstrated the presence of bismuth, cobalt, and selenium in the prepared sample. Congo red dye (CR) was degraded using the prepared BCSN-CM in sunlight irradiation, and operational parameters were evaluated to optimize the conditions responsible for maximum dye degradation. It was found that degradation of dye depends on factors like catalyst amount, irradiation time, dye concentration, and pH of dye solution. The degradation efficiency of prepared microspheres was found to be 85% of the 90-ppm solution under optimized conditions in sunlight irradiation for 100 min. The first-order kinetics was well fitted to degradation of CR having a rate constant of 1.50 × 10-2 min-1. Moreover, the prepared sample gave an excellent result after regeneration and reused up to five cycles. The newly fabricated chitosan-bismuth cobalt selenide hybrid microspheres might display a high potential for the removal of organic pollutants from the dye and textile industries wastewater.

Selenide-chitosan as High-performance Nanophotocatalyst for Accelerated Degradation of Pollutants.

Water pollution is one of the major global challenges today. Water bodies are contaminated by the heavy release of waste effluents of textile industries, which includes intensively colored dye pollutants. Herein, a ternary nanocomposite of bismuth copper selenide with small particle size and ternary metal selenide (TMS)-chitosan microspheres (TMS-CM) of the spherical porous surface were successfully synthesized. SEM, XRD, EDX, FTIR, and UV/Vis spectrophotometry analysis revealed the structural and morphological characteristics of the newly synthesized nanocomposites. SEM imaging showed the average diameter of TMS nanoparticle to be 33 nm. The crystal size was calculated as 6.33 nm and crystalline structure as orthorhombic using XRD findings. EDX confirmed the presence of Bi, Cu, and Se in the ternary nanocomposite. The bandgap of 1.8 eV was calculated from Tauc's plot for the TMS nanocomposite. SEM confirmed the successful synthesis of spherical TMS-CM microspheres of porous surface morphology with an average size of 885.6 µm. The presence of chitosan microspheres in the synthesis of TMS nanocomposite was identified by FTIR spectral analysis. Furthermore, highly efficient photocatalytic degradation (up to 95.4%) of ARS was achieved within 180 min at pH 4.0 using 0.5 g of TMS-CM in sunlight. The first-order kinetic model fitted well to the photocatalytic decontamination of ARS using TMS-CM with a rate constant of 6.1x10-2  min-1 . The TMS-CM gave attractive results and high efficiency in photocatalytic degradation of ARS dye after reusing and regeneration of up to seven successive cycles. The newly synthesized nanophotocatalyst could be efficiently used for the decontamination of dye polluted water from textile industries.