Synthesis: CdS Nanoparticles by Using Sol-Gel for Wastewater Treatment (Research Paper Sample)

SYNTHESIS OF CdS NANOPARTICLES BY USING SOL-GEL FOR WASTEWATER TREATMENT
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Abstract
This project aims at performing a synthesis of CdS nanoparticles by using sol-gel for wastewater. Semiconductor nanoparticles with controllable silica matrix size and stability using a room temperature sol-gel process was used to prepare CdS. Using the respective metal precursors and Tetraethylorthosilicate (TEOS) as a silica matrix source, cadmium sulfide nanoparticles were synthesized. The sol-gel process is a method for producing solid materials from small molecules actors. It can control the particle size and morphology through systematic monitoring of reaction parameters. For that, SEM and XRD tests will be performed. The hope remains for the continuation of the effective scientific research process in thin films, especially CdS membranes, because of their many properties and attractive applications, which have enabled them to occupy an important position for researchers. This is to improve its properties to optimize its use in various electronic devices and scientific applications.
Key Words: CdS nanoparticles, Sol-gel, SEM test, XRD test, Tetraethylorthosilicate (TEOS), methods of sedimentation,
Synthesis of CdS Nanoparticles by Using Sol-Gel for Wastewater Treatment
Introduction
CdS nanoparticles have generated a great interest in the engineering world because they have unique size-dependent physical and chemical properties. Besides, it is a Group 2-4 semiconductor, which has further resulted in additional research to be carried out on CdS. Amongst the industrial areas in which CdS may be applied are; manufacture of solar cells, the luminescence device industry, the photochemical catalysis industry, and the non-linear optical materials industry (Martínez-Alonso et al. 2015, p5543; Yang et al. 2011, p. 377)
The other experimental study conducted by Belet et al. (2019, p.126) investigates the performance of several photocatalysts, with the view to finding out which product would serve as the best alternative for wastewater purification. Through a sol-gel process, the photocatalysts were deposited as thin films, with each photocatalyst's efficiency being measured through the degradation of methylene blue, amongst a list of a wide range of other pharmaceutical products. This experimental study employs the use of two primary forms of synthesis; organic syntheses and aqueous syntheses. Reactions in the organic syntheses processes occur in an organic solvent, with only a stoichiometric amount of water present, while the aqueous syntheses reactions take place in water. In summary, the best performances for the pharmaceutical product degradation took place when silver nanoparticles and Evonik P25 were added to TiO2 (Belet et al. 2019, p.126).
Key Findings of Literature Authors
In the research article by Hooi Ling Lee et al. (2010, p.2069) on the Thermal and Optical Properties of CdS Nanoparticles, the key findings included the observation that it was possible to confirm the structural properties of CdS samples by the use of H-NMR spectroscopy. According to Davar (2013, p.637) and Wu et al. (2010, p.748), the XRD microscopic patterns for both the pure CdS sample and the CdS nanocomposites were similar, even when compared to standard procedures, samples, and standards. When observed for PL spectroscopy, however, both the CdS pure sample and the CdS nanocomposites sample indicated different values of photoluminescence intensity and different Raman pattern values. It was also noted that both the melting and isotropization temperatures of both samples were different, with the pure CdS sample indicating somewhat higher melting and isotropization temperatures than the composite sample.
Figure SEQ Figure \* ARABIC 1: Nanoparticles formation mechanism in reversed micelles (Liveri 2006)
The methodology used in the given paper
Experiment 1
A spectrometer (Bruker 400 MHz) was used to test and measure the samples, which at this point had been prepared at a recommended concentration of 100mg/mL in CDCl3. The resolution at the spectrometer stood at approximately 2 cm-1.
For the synthesized nanocomposite sample, it was identified by the powder X-Ray Diffraction (XRD).
A few drops of dispersion fluid were placed on the copper grid. At that point, the solvent was caused to evaporate. An energy-dispersive x-ray machine was used to observe both the minute elemental composition and morphology of both samples under study.
Throughout the experiment, the CdS samples were mounted using double-sided tape onto the metallic holders before the powders being coated with gold for optimum visibility.
An additional filter was suitably placed in front of the detector to avoid the infraction of the generated excitation lines from the sample diffusion.
Low power beams with 20mW Wattage at the sample's surface have been used to protect the experiment samples from damage through heating.
The ethanol-sample mixture was then refluxed while being stirred for 12 hours at a constant temperature of 130 degrees Celcius. Once the 12 hours elapsed, the mixture was precipitated by immersion into a 2 liter distilled water tub. The precipitate was then filtered and rinsed using diethyl ether before being tried in a vacuum drier oven at 90 degrees Celcius. The final phase of purification was then carried out through chemical re-crystalization using DMF:1-butanol. Green crystals were yielded at this point; sometimes, the procedure would yield brown crystals.
Experiment 2
The primary premise for this experiment's setup is that pharmaceutical compounds in wastewater effluent would be broken down using what has grown to be known as quarternary treatments. This study aims to identify, therefore, to identify the most efficient sol-gel produced thin-film heterogeneous photocatalyst from a list of 7 materials, placing a high priority on inexpensive materials and methods. Given these considerations, a number of conditions had to be met before this experiment proceeded;
1 The sol-gel method had to have been used. It is a relatively cheap yet effective synthesis method, considering the relatively low temperature and pressure of soft chemistry requirements (Kumar et al. 2015, p.606X).
2 The photocatalyst needed to be able to be deposited in a thin layer on a sheet of glass.
3 The photocatalyst needed to be active under the influence of UV light.
4 The price of the entire synthesis process needed to be relatively low.
Within the general view and objectives of this experimental study, this chemical synthesis method should be able to be sufficiently carried out at an industrial scale to benefit the highest number of people without being prohibitively expensive.
Pure aqueous Titanium dioxide solution TiO2 aq was added to HAc and TTiP, and the solution stirred gently for 15 minutes at room temperature in a closed container.
A white precipitate was obtained and decanted before being cleaned vigorously using pure water, a process that was repeated for two more cycles.
The same water volume was also added into the mixture together with HNO3, and the solution stirred vigorously for 16 hours at 45 degrees Celcius.
Nanocrystallites of Titania were dispersed in the resulting mixture.
Parameters used for Analysis in the experiment
Experiment 1
All the data was collected using an X-ray diffractometer that had a monochromatic radiation filter. Besides, the average particle size throughout the entire experiment was obtained through the use of a powerful transmission electron microscope that operates at a notable 200kV. Another parameter under observation was the samples' particle size, which was determined using the Docu Image Analyzer. Differential Scanning calorimetry, on the other hand, was observed using the Perkin-Elmer instrument, which has a heating rate of approximately 5 degrees Celcius per minute in liquid nitrogen. Besides, liquid crystalline mesophase was also examined using a Nikon polarising optical microscope equipped with a Linkam hot stage, temperature controller, and cooling system.
Another parameter examined in this study was the photoluminescence parameter. The excitation wavelengths of the samples were obtained using the UV lines of a mercury lamp source. The dichromatic mirror and the bandpass filter were used to avoid the visible source range emissions and select the desired lines, respectively. The nanocomposites' optical properties were examined in a UV spectrophotometer, with the nanocomposites dispersed in a solution of ethanol.
Experiment 2
The coated glass slides were measured for thickness at various points on their surfaces, ultimately calculating each glass slide's thickness's global average and standard deviation.
Important Conclusions from the reviewed literature
Experiment 1
Besides holding the potential to become a purification catalyst in wastewater lands, the tested CdS monomer exhibited properties that make it a potential light-harvesting device. However, this requirement may only be met if conditions are optimized to as close to laboratory conditions as possible. Deep trap defects were noted in the yielded nanocomposite samples, judging from them being found in the red-shift region. The red-shift emissions were attributed to the particles being near each other. This experimental study indicates that the used monomers indicate more significant potential when the CdS is added in a ...