The influence of Triton X-100 surfactant on the morphology and properties of zinc sulfide nanoparticles for applications in azo dyes degradation
Graphical abstract
Introduction
Metal sulfides, mainly as nanoparticles, have applications in a variety of devices, such as solar cells, light-emitting diodes, sensors, thermoelectric devices, lithium-ion batteries, fuel cells and nonvolatile memory devices [1]. The synthesis of metal sulfide colloidal nanoparticles typically consists in a chemical reaction between a metal salt and a sulfide ion precursor, in the presence of capping agents, in order to stabilize the high energy surface of the nanoparticles and protect them from aggregation. The colloidal nanoparticles are synthesized and stabilized in solution by using of organic molecules or polymers which could bind on the particle surface; the linked molecules are often denoted as either surfactants, ligands, or capping agents in the literature [2], [3], [4].
Among metal sulfides, zinc sulfide has focused strong interest in many areas of research, being extensively studied, especially as nanomaterial [3], [4], [5]. However, new aspects are continuously evidenced and ZnS is still of interest for researchers. As an important II–VI semiconducting material, ZnS has wide band-gap energy (3.7 eV) and a large exciton energy (≈40 meV) [1]. Actually, zinc sulfide has band-gap energy mainly in the range of 3.6–3.9 eV, depending on its structure and morphology. Various shapes of ZnS, like spheres, rods, tubes and wires, were successfully prepared; the shape and also the size can be varied from bulk particle to nanocrystal, depending on synthetic route, hence the morphology of the particles can be tuned by varying the reaction parameters [4], [5].
Nanostructured ZnS has versatile potential applications in optoelectronic devices, due to its excellent properties of luminescence and photochemistry (e.g. flat-panel displays, injection lasers, ultraviolet light-emitting diodes, thin film electroluminescent displays, in solar energy power, etc.) [1], [5]. Owing to the highly negative reduction potentials of excited electrons and the rapid generation of electron–hole pairs, zinc sulfide is also used as semiconductor photocatalyst in green synthesis of organic compounds (like substituted tetrazoles [6], xanthene and its derivatives [7], etc.) and in the removing of water toxic organic pollutants (e.g. photocatalytic degradation of azo dyes like reactive black 5 [8], Ponceau S and crystal violet [9], malachite green [10], thymol blue [11], Victoria blue R [12], methyl violet [13], reactive red 43 [14], reactive blue 19 [15], or other pollutants) [1]. ZnS quantum dots doped with metal ions, like Fe3+ [10], [11], [13], Sm3+ [14], Pr3+ [15], etc., can prove superior catalytic activity compared to pure nanocrystals. Furthermore, nanoparticles of ZnS exhibit superior photocatalytic activity because of the increased surface/volume ratio with enhanced redox potential as compared to their bulk counterpart and trapped holes arising from surface defects [9].
The synthesis routes for zinc sulfide are one-pot synthesis, sol-gel technique, hydrothermal method, solid state reaction, etc. [3], [4], [5], [16]. For semiconductors nanoparticles synthesis, various surfactants can be employed in order to form a monolayer on the nanoparticles surface, e.g. carboxylates, sodium citrate, oleic acid, etc., and synthetic polymers (polyethylene glycol, Triton X-100, polyvinyl alcohol, etc.), whose nature may strongly influence the nanoparticles properties [17]. The capping agents play a versatile role in colloidal synthesis of nanoparticles other than stabilizers, often acting as ligands for metal ions forming coordination compounds. The particles shape could be modified in the capping agents presence and, in many cases, capping agents act as a physical barrier to restrict the free access of reagents to catalytically active sites on the particle surface. The so-called “surface clean” nanoparticles generally are not truly naked but they are free of long-chain organic compounds, being stabilized by small molecules, including intentionally added small adsorbates, solvent molecules, solute ions, and gases from the nanoparticle growth or storage surroundings; those small molecules are easily displaced by reactants during catalytic reactions [2].
Having in view the importance of surfactants in the properties of ZnS nanoparticles, herein we report the synthesis of capped ZnS nanoparticles in order to optimize the properties, including photocatalytic properties, which evidenced the surfactant importance (Triton X-100) in nanoparticles structure and properties. All synthesized ZnS samples exhibited good catalytic properties in the discoloration of Congo red solution.
The azo dyes are used in large quantities in textile industry and wastewaters from this contain high amount of dyestuff. The textile dyes often have aromatic structure and do not degrade easily under natural conditions because of their highly photostability; as well, very small amounts of dye in water (less than 1 ppm for some dyes) are visible and undesirable [9].
The Triton X-100 capped ZnS nanoparticles can be used in the organic pollutants photocatalytic degradation from wastewaters.
Section snippets
Materials
The high purity reagents from Sigma-Aldrich (zinc acetate, Zn(CH3COO)2·2H2O; Triton X-100, TX; ammonia aqueous solution, 25%; Congo red; sodium hydroxide, NaOH) and Merck (thioacetamide, TAA; hydrochloric acid 37%, HCl) were used as received, without further purification. Congo red is denoted the disodium salt of 3, 3′-([1,1′-biphenyl]-4,4′-diyl)bis(4-aminonaphthalene-1-sulfonic acid) (CR, C.I. Direct Red 28, M.W. = 696.67 g mol−1, C32H24N6O6S2Na2).
Synthesis of ZnS nanopowders
For the synthesis of zinc sulfide sample
Results and discussion
The influence of capping agents in the synthesis of colloidal metal sulfides nanoparticles was studied in last years. According to some authors, ligands are necessary to stabilize nanoparticles during synthesis but, once the particles have been deposited on a substrate, the presence of the ligands is detrimental for catalytic activity [24], thus the removing of capping agents will be required for a good catalytic activity.
In the present study, we used a very efficient surfactant, Triton X-100
Conclusions
We obtained TX-capped ZnS nanopowders with high catalytic activity by one pot synthesis using thioacetamide as sulfide ion source and Triton X-100 as surfactant. The syntheses were performed in aqueous solution, respective in Triton X-100 as solvent, through two experimental techniques and varying the reaction time.
All the synthesized samples have cubic structure, with the crystallites size under 10 nm, entitling them as nanocrystals. The nanoparticles obtained in absence of water as solvent
References (47)
- et al.
A comprehensive review on ZnS: from synthesis to an approach on solar cell
Renew. Sust. Energy Rev.
(2016) - et al.
Photocatalytic degradation of reactive black 5 azo dye by zinc sulfide quantum dots prepared by a sonochemical method
Mat. Sci. Semicon. Proc.
(2013) - et al.
High-performance pure and Fe3+-ion doped ZnS quantum dots as green, nanophotocatalysts for the removal of malachite green under UV-light irradiation
J. Hazard. Mater.
(2013) - et al.
Quantum dot based photocatalytic decolorization as an efficient and green strategy for the removal of anionic dye
Mat. Sci. Semicon. Proc.
(2015) - et al.
A comparison investigation on photocatalytic activity performance and adsorption efficiency for the removal of cationic dye: quantum dots vs. magnetic nanoparticles
J. Environ. Chem. Eng.
(2016) - et al.
Study of photocatalytic activity of ZnS quantum dots as efficient nanoparticles for removal of methyl violet: effect of ferric ion doping
Spectrochim. Acta A
(2014) - et al.
Synthesis and characterization of samarium-doped ZnS nanoparticles: a novel visible light responsive photocatalyst
Mater. Res. Bull.
(2016) - et al.
Praseodymium-doped ZnS nanomaterials: hydrothermal synthesis and characterization with enhanced visible light photocatalytic activity
J. Ind. Eng. Chem.
(2016) - et al.
Effects of surfactants on the magnetic properties of iron oxide colloids
J. Colloid Interf. Sci.
(2014) - et al.
Facile synthesis, characterization and application of functionalized cadmium sulfide nanopowders
Mater. Chem. Phys.
(2016)
Properties of PEG-capped CdS nanopowders synthesized under very mild conditions
Powder Technol.
Photocatalytic degradation of methylene blue under visible light using PVP-capped ZnS and CdS nanoparticles
Sol. Energy
Homogeneous and heterogeneous AOPs for rapid degradation of Triton X-100 in aqueous media via UV light, nano titania hydrogen peroxide and potassium persulfate
Chem. Eng. J.
Some aspects of the role of surfactants in the formation of nanoparticles
Colloid. Surf. A
Effect of film thickness on the energy band gap of nanocrystalline CdS thin films analyzed by spectroscopic ellipsometry
Phys. E
Preparation and band gap energies of ZnO nanotubes, nanorods and spherical nanostructures
Powder Technol.
Investigations on the influence of surfactant in morphology and optical properties of zinc oxide nanopowders for dye-sensitized solar cells applications
Mat. Sci. Semicon. Proc.
Low temperature synthesis, characterization and photoluminescence study of plate-like ZnS
Mater. Lett.
Low temperature synthesis and blue photoluminescence of ZnS submicron particles
Mater. Lett.
Review of photoluminescence performance of nano-sized semiconductor materials and its relationships with photocatalytic activity
Sol. Energ Mat. Sol. Cells
Photocatalytic degradation of Congo red using Carissa edulis extract capped zinc oxide nanoparticles
J. Photochem. Photobiol. B
Photocatalytic degradation of various types of dyes (alizarin S, crocein orange G, methyl red, Congo red, methylene blue) in water by UV-irradiated titania
Appl. Catal. B Environ.
Photo catalytic degradation of Alizarin red S using ZnS and cadmium doped ZnS nanoparticles under unfiltered sunlight
Surf. Interfaces
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