Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy
Improved photocatalytic activity of CdSe-nanocomposites: Effect of Montmorillonite support towards efficient removal of Indigo Carmine
Graphical abstract
Introduction
Synthetic dyes emanated by textile, leather and printing industries causing contamination in water resources is a serious environmental concern [1]. Currently, many methods are employed to remove dyes from polluted water, that include sedimentation, coagulation, flocculation, chemical treatments, oxidation, electrochemical methodology, photodecomposition, biological treatments, adsorption, and membrane process [2]. Among these, photocatalysis involving semiconductor nanoparticles under visible light have been extensively studied as it is considered to be a cleaner and greener, lesser photo-corrosive and therefore, is thought to be sustainable approach towards removal of variety of aquatic pollutants [3]. In recent past, different strategies are formulated towards enhancing their photocatalytic activity that include the surface modifications, doping of transition or non-transition metals ions and the immobilization of nanoparticles on to a solid support [4], [5], [6].
CdSe, an n-type semiconductor having band gap in the visible light (1.65–1.8 eV) [7], [8], [9], has received wide applications in labeling [10], sensors [11], optometric devices [12], solar cells [8], [13] and photocatalysis [7]. Although it has extensively been employed for biological applications, its immobilization onto a solid support for photocatalytic applications is by and large has been less explored. It is interesting to note that CdTe nanoparticles [14] and Cd(OH)2 nanowires [15]; both supported on activated carbon has recently been employed as an adsorbent for removal of dyes from aqueous medium. Clay minerals; a class of inorganic layered compounds is commonly available, robust and photochemically inert material that can be tailored into variety of functional solid adsorbents due to their flexibility in composition, structure and beneficial adsorption capacities [16]. Clays and organically modified clays are good adsorbents for removal of organic dyes from waste water [17], [18]. Thus, it is imperative to develop a simple and ingenious approach by combing its features with semiconducting nanoparticles that may result in engineering the “designer photocatalyst” towards green and sustainable technologies.
MMT has quite often been used as an adsorbent for dyes and pigments because of stronger cation exchange capacity and presence of active surface sites [19]. Considering these facets, two synthetic strategies are adopted for the synthesis of CdSe-nanocomposites: (a) in-situ formation of CdSe dispersed in the MMT structure and (b) wet impregnation of preformed CdSe on to the MMT surface. Such an approach has two advantages: (i) it will differentiate the effectiveness of CdSe and (ii) alteration in adsorption behavior may lead to changes in reaction rates of photochemical process. The major impetus for the present work is to establish the effective adsorption of IC through photochemical process occurring on the catalyst surface that possess reactive sites generated by adopting two synthetic approaches for CdSe-MMT nanocomposites. Since the physical and catalytic properties of these two types of photocatalysts are thought to be different, we envisage that their adsorption capacity shall be dissimilar as a consequence of alternations and modifications in the MMT matrix. These concepts are systematically investigated with Indigo Carmine (IC) (Supplementary data; Fig. S1) by employing different adsorption isotherms like Langmuir, Freundlich as well as Redlich–Peterson, Dubinin–Radushkevich, Temkin and Flory–Huggins. Since adsorption phenomenon is manifested through diffusion controlled mechanisms, intra-particles diffusion models like Webber–Morris and Boyd plots are also evaluated to understand the diffusion process expected for nanocomposite-dye interactions.
In the present work, visible light induced adsorptive removal capacity of CdSe-MMT nanocomposites is evaluated to understand the role of MMT on photo-adsorption and the dynamics of removal process for IC molecule.
Section snippets
Chemicals
The following compounds are used as received: IC (Hi-Media Chemicals, UK) Cadmium acetate (Cd(OAc)2⋅2H2O), Loba Chemie, UK), Selenium powder (Loba Chemie, UK), Ethylene glycol (Loba Chemie, UK), Montmorillonite K-10 (Fluka) Sodium borohydride (NaBH4, Loba Chemie, UK), and Sodium chloride (NaCl, Loba Chemie, UK). All the chemicals were of analytical grade and are used as received. Deionized water is used throughout the experiments.
Preparation of modified Montmorillonite (MMT)
MMT treated with excess 1 M NaCl solution is stirred for 24 h,
XRD and TEM analysis of nanocomposites
MMT exhibits peaks at 8.93°, 19.95° and 26.71° (Fig. 1) corresponding to (0 0 1), (0 2 1 1) and (0 0 5) plane due to random stacking of clay layers [20], [21], [22]. On the hand, CdSe NP’s exhibited characteristic reflections at 25.36°, 42.7° and 50.58° corresponding to (1 1 1), (2 2 0), (3 1 1) planes of the CdSe nanocrystals [23]. During the composite formation, peaks corresponding to either MMT or CdSe NP’s are not significantly changed implying that CdSe NP’s are located on the surface of MMT rather
Conclusions
The present work clearly establishes that MMT surface indeed contributes towards efficient removal of IC on the catalytic surface of CdSe-MMT composites. Smaller sized CdSe NP’s that are properly dispersed in the clay matrix, essentially enhance the photochemical process through synergism in composite and such an effect eventually leads to spontaneous surface adsorption behavior as described by Redlich–Peterson and Flory–Huggins isotherm models. This adsorption process can best be ascribed as
Acknowledgements
Authors are thankful to Dr. A.D. Natu Head, Dept. of Chemistry and Principal, A.G. College, for constant encouragement and support. DST, New Delhi is acknowledged for providing FIST Grant.
References (42)
- et al.
Appl. Catal. B: Environ.
(2003) - et al.
J. Hazard. Mater.
(2004) - et al.
Sol. Energy Mater. Sol. Cells
(2011) - et al.
Physica E
(2009) - et al.
J. Colloid Interface Sci.
(2011) - et al.
Sens. Actuators B
(2008) - et al.
Microelectron. J.
(2008) - et al.
Electrochim. Acta
(2010) - et al.
Spectrochim. Acta A
(2012) - et al.
Spectrochim. Acta A
(2012)
J. Colloid Interface Sci.
Microporous Mater.
Chem. Eng. J.
Ultrason. Sonochem.
Spectrochim. Acta A
J. Hazard. Mater.
Spectrochim. Acta A
Desalination
Dyes Pigments
J. Colloid Interface Sci.
Synth. Met.
Cited by (19)
Improved photocatalytic performance in Ce<sup>3+</sup> doped CoFe<inf>2</inf>O<inf>4</inf> nanoparticles by modifying structural, optical, and magnetic properties
2024, Materials Science in Semiconductor ProcessingGraphene oxide/ZnO nanocomposites for efficient removal of heavy metal and organic contaminants from water
2023, Arabian Journal of ChemistryStudy of photo catalytical, antimicrobial activity, dielectric and ac impedance properties of Zn doped Mg nanoferrites synthesized from citrate gel auto combustion method
2022, Materials Chemistry and PhysicsCitation Excerpt :The advanced oxidation process is a very good process to remove organic pollutants even in the waste water compared to the rest methods such as Adsorption, filtration, and precipitation [6,7]. Antibacterial agents play significant role in industrially such as water disinfection, textiles, construction, packing, and food products [8,9]. Spinel nano particles have many uses, most notably water treatment, data storage, bio-medical, colour imaging, anti-microbiological activity, cores of transformers, sensors, drug delivery etc [10,11].
A facile hydrothermal synthesis of novel CeO<inf>2</inf>/CdSe and CeO<inf>2</inf>/CdTe Nanocomposites: Spectroscopic investigations for economically feasible photocatalytic degradation of Congo red dye
2021, Inorganic Chemistry CommunicationsCitation Excerpt :The synthesis-steps of CeO2 NPs via the hydrothermal technique were summarized in Scheme 1. In the Teflon-vessel, selenide precursor was firstly prepared by dissolving 0.378 g (0.01 mol) of NaBH4 in 25 mL of deionized water then 0.263 g of sodium selenite (1 mmol) is added with vigorous stirring for 1 h under N2-gas bubbling till orange-red color of NaHSe is obtained [33]. After that, 25 mL of Cd-acetate solution (1 mmol) is added slowly into the solution with constant stirring to obtain a brownish suspension, 0.172 g of as-prepared CeO2 (1 mmol) is dispersed in the previous solution by vigorous stirring for 1 h.
Adsorption and photocatalytic performance of Au nanoparticles decorated porous Cu<inf>2</inf>O nanospheres under simulated solar light irradiation
2021, Applied Surface ScienceCitation Excerpt :The pseudo-first-order model is based on the assumption that adsorption occurs on the adsorbent surface and exclude the interaction between adsorbed molecules. The second-order model is applicable for the heterogeneous adsorption and controlled by chemisorption [54,55]. The adsorption curves are fitted by pseudo-first-order and pseudo-second-order models, respectively, as displayed in Fig. 7 and Fig. 8.
Impact of the stacking fault and surface defects states of colloidal CdSe nanocrystals on the removal of reactive black 5
2021, Materials Science and Engineering: BCitation Excerpt :CdSe nanocrystals, a n-type semiconductor having aband gap energy of ~1.74 eV at room temperature, have shown interesting properties as effective photocatalysts. They have shown highly negative redox potentials of excited electrons and arapid generation of electron-hole pairs [41–46]. The large surface-area-to-volume ratio of these nanostructures enhances the photo-efficiency, photostability and maximizes the interfacial areas between NCs and dye molecules to improve the catalytic degradation [47].