Visible light assisted photocatalytic degradation of Rhodamine B dye on CdSe-ZnO nanocomposite: Characterization and kinetic studies

Abstract

The paper involves the heterogeneous photocatalytic degradation of Rhodamine B dye (RhB) employing ZnO and ZnO/CdSe nanocomposites as photocatalysts which was synthesized via chemical bath deposition (CBD) method. Nanocomposite CdSe-ZnO powders have been synthesized by varying CdSe/ZnO molar ratios. The structural, optical, morphological, and topological characteristics of as synthesized materials were investigated using the appropriate characterization instrument such as X-ray diffractometer (XRD), diffuse reflectance spectrophotometer (DRS), atomic force microscope (AFM) and field emission scanning electron microscope (FE-SEM). It seems that the growth of CdSe particles onto ZnO particles in a core-shell like structure. The photocatalytic performance of ZnO/CdSe nanocomposite has been investigated under affecting factors such as catalyst dosage, RhB concentration and initial pH of RhB solution. The photocatalytic degradation reactions were carried out by exposing the aqueous suspension of the dye and ZnO/CdSe system with visible light. The residual concentration of RhB dye was measured using a UV-visible spectrophotometer at maximum wavelength of dye (λmax 554 nm). The decolorization process was found to follow pseudo first-order kinetics which is well expressed by the represented by the Langmuir-Hinshelwood (L-H) kinetic model. The maximum decolonization efficiency of 99% was achieved within 180 min at optimum conditions, dye conc. 10 mg/L, pH 10, CdSe (10%)-ZnO dose 1.5 g/L. The ROS studies indicate that hydroxyl radicals and holes are the predominant reactive species within the same step. Furthermore, CdSe(10%)-ZnO shows a good stability after reuse for 15 successive cycles and hence it expected to be promising in polluted water treatment.

Facile sonochemical method for preparation of Cs2HgI4 nanostructures as a promising visible-light photocatalyst

“…Several previous studies have reported on several reactions that take place in a photocatalytic process and involve H 2 O 2 , •OH and O 2 • − . Hence, the relevant reactions on the Cs 2 HgI 4 surface making the colorant degeneration can be described below [35] , [36] , [37] , [38] : Cs 2 HgI 4 + hν (Visible) → Cs 2 HgI 4 (e − + h + ) Cs 2 HgI 4 (e − ) + O 2 → Cs 2 HgI 4 + O 2 • − Cs 2 HgI 4 (h + ) + H 2 O → Cs 2 HgI 4 + H + + OH• Cs 2 HgI 4 (h + ) + OH − → Cs 2 HgI 4 + OH• H 2 O 2 →hν2•OH H 2 O (ads) + h + → •OH + H + OH − (ads) + h + → HO• O 2 + e − → O 2 • − O 2(ads) + e − + H + → HO 2 • HO 2 • + HO 2 • → H 2 O 2 + O 2 O 2 • − + HO 2 • → HO 2 − + O 2 HO 2 − + H + → H 2 O 2 H 2 O 2(ads) + e − → •OH + OH − H 2 O 2 + O 2 • − → •OH + OH − + O 2 H 2 O 2(ads) + 2 h + → O 2 + 2H + H 2 O 2(ads) + 2H + + 2e − → 2H 2 O H 2 O 2(ads) + h + → HO 2 • + H + O 2(ads...…”

Evaluation of the Applicability of Modifying CdSe Thin Films by the Addition of Cobalt and Nickel to Enhance the Efficiency of Photocatalytic Decomposition of Organic Dyes

“…As was shown by the authors [38], a decrease in particle size leads to an increase in the efficiency of decomposition, which also coincides with the results of this work, according to which the formation of finer grains in NiCdSe and CoCdSe also affects decomposition efficiency. The highly efficient influence of composite structure formation achieved by the modification of CdSe materials by adding ZnO to them on the subsequent formation of nanocomposites was demonstrated in [40]. According to the results of [40], the formation of a nanocomposite of the ZnO/CdSe type leads to the formation of stable photocatalysts capable of operating for more than 15 consecutive cycles, which also confirms the assumption made in this study about the influence of nickel and cobalt on increasing the stability of long-term photocatalyst operations.…”

“…The highly efficient influence of composite structure formation achieved by the modification of CdSe materials by adding ZnO to them on the subsequent formation of nanocomposites was demonstrated in [40]. According to the results of [40], the formation of a nanocomposite of the ZnO/CdSe type leads to the formation of stable photocatalysts capable of operating for more than 15 consecutive cycles, which also confirms the assumption made in this study about the influence of nickel and cobalt on increasing the stability of long-term photocatalyst operations. The results obtained in this work on the efficiency of the photocatalytic decomposition of organic dyes are in good agreement with the results of work [41], which examined three types of photocatalysts based on CdSe modified with graphene and TiO 2 .…”

Preparation complexes Co(III), Ni(II), and Cu(II) with novel azo-Schiff base ligand (N, N, O) derived from 2- amino- 6- methoxy benzothiazole with spectral characterization, study biological activity as anti-cancer, anti-oxidant to complexes

“…And the proposed geometry is octahedral with deformed deformation, and the deformation type is compressed (Z-in) or dragged (Z-out). The most common possibility is (Z-out) and its sp3d2 hybridization (Alshamsi et al 2021).…”