Current Physical Chemistry - Volume 15, Issue 1, 2025

To study the micellar effect of SDS on the oxidation of glycine by Quinolinium Dichromate (QDC) in perchloric acid medium.

Among the amino acids, glycine plays a major role in multiple metabolic reactions, such as glutathione synthesis and one-carbon metabolism. The oxidation of glycine has received importance because it is the major neurotransmitter inhibitor in the spinal cord and brainstem. In the oxidation process of amino acids, highly toxic chromium (VI) compounds are converted into non-toxic chromium (III) by quinolinium dichromate (QDC) oxidant in an appropriate pH value medium.

1. To study the catalytic role of anionic surfactant (SDS) on the oxidation of glycine by QDC through micellization, evaluation of critical micelles concentration (CMC) in the presence and absence of glycine and other surface properties along with thermodynamic quantities. 2. Determination of rate constant and order of reaction with respect to QDC, glycine, acid and surfactant which will help to study the kinetics of the reaction 3. Analysis of oxidation product by FT-IR and calculation of activation parameters. 4. Synthesis of oxidant (QDC) and its characterization by UV-Visible spectrophotometer and NMR spectroscopy.

The reaction was monitored spectrophotometrically at λmax = 440 nm using Systronics Spectrophotometer-166 and 2203. The reaction mixture containing glycine, perchloric acid, SDS and water was taken in a separate flask in a thermostat and the oxidation reaction was started by adding the required amount of oxidant.

First-order kinetics was observed with respect to oxidant, glycine and hydrogen ions. The rate of reaction increased remarkably with an increase in the concentration of surfactant (SDS). The kinetic results show that the ionic strength variation does not have any significant effect on the rate whereas the increase in the dielectric constant of the medium shows a remarkable effect on the rate constant. From stoichiometry study, it was found that 2 moles of oxidant (QDC) consumed 3 moles of glycine to produce aldehyde (Formaldehyde).

The observed negative value of (ΔS) entropy of activation and positive (ΔH) enthalpy of activation suggests a more ordered activated complex formation and highly solvated transition state. The kinetics of the reaction in a perchloric acid medium is found to be accelerated in the presence of surfactant (SDS). The kinetics of the reaction follow pseudo first-order decay of Cr(VI) species (QDC), a unity dependence of rate on glycine and perchloric acid. The oxidation product formaldehyde was identified by FTIR. NMR spectrum analysis of synthesized QDC shows a resemblance with pure QDC.

The interaction of dyes (crystal violet, malachite green, and congo red) with cationic (cetrimide) and anionic surfactants (sodium dodecyl sulfate) in the aqueous medium were studied via conductometric and UV-visible spectroscopy.

The critical micelle concentration (CMC) of both cetrimide and SDS upsurges in all the selected dyes on increasing the temperature. Thermodynamic parameters like change in Gibb’s free energy of micellization , change in enthalpy of micellization as well as change in entropy of micellization were calculated by employing mass action model.

The values obtained are positive with and values being negative signified that the phenomenon of micellization is spontaneous as well as exothermic in nature. Moreover, the more negative in water as well as in the presence of dyes signify the presence of electrostatic forces of attraction between the oppositively charged dyes and surfactant moieties. UV-spectroscopy reveals that spectral changes occur because of the interaction of surfactants with dye molecules.

By analyzing shifts in absorption peaks, changes in intensity, and alterations in band shape, insights into the nature of surfactant-dye complexes and their potential applications in various industries can be assessed. This understanding can help in the design and optimization of products and processes involving surfactants and dyes.

Barium Titanate (BaTiO3) is a good candidate for a variety of applications due to its excellent dielectric, ferroelectric and piezoelectric properties.

Pure and doped Barium Titanate (BTO) nanoparticles have been synthesized by the sol-gel method. Barium hydroxide octahydrate (Ba (OH)2.8H2O) and titanium (IV) iso-propoxide (Ti {OCH[CH3]2}4) were used as starting materials. Apart from pure Barium Titanate nanoparticles, Fe-doped BaTiO3 nanoparticles of three different concentrations: 0.1, 0.2 and 0.3 in mol% were prepared and characterized using X-ray diffraction (XRD), UV visible spectroscopy, Fourier Transform Infrared Spectroscopy (FTIR).

From the X-ray diffraction pattern, the particle size was found to be varied in a range of 17-25nm. By using UV visible spectroscopy it was observed that the band gap energy of pure BaTiO3 NP is 3.2eV. As the pure BaTiO3 nanoparticles are doped with 0.1% Fe, the band gap reduces to 3.175eV. For BaTiO3 doped with 0.2% and 0.3% Fe, the band gap energy values are 2.709 and 2.652 respectively. FTIR spectra were used to analyze the vibrational modes of BaTiO3. From the result obtained from FTIR, we can see that the absorption spectrum ranges from 450 cm^-1-4000 cm^-1. The prominent peak of pure BaTiO3 is at 500 cm^-1 which is due to the vibration of the Ti-O band in crystal lattice. For BaTiO3 doped with Fe2O3, the wave number of the absorption peak is shifted from 500 cm^-1 in pure BaTiO3. The antibacterial studies were conducted on Pseudomonas aeruginosa, Staphylococcus aureus and Escherichia coli.

Both pure and Iron-doped Barium Titanate showed significant antibacterial properties, confirming the antibacterial property of Barium Titanate nanoparticles.

Concrete's filler material gets strengthened over time by specific chemical reactions that harden it. Multi-walled carbon nanotubes (MWCNTs) are more frequently used as fillers than SWCNTs, owing to their lower cost of production and their superior reinforcement properties in cement composites.

Mechanical properties like compressive strength, splitting tensile strength, and modulus of elasticity are proportional to the water/cement ratio (w/c) and are considered critical criteria in the design of structural elements.

The aim of the present work was to prepare, characterize, and determine the effects that multi-walled carbon nanotubes (MWCNTs) can have on the mechanical strength of various matrix cementitious composites.

The results showed that the addition of multi-walled carbon nanotubes to the concrete greatly improved both its compressive strength and its splitting tensile strength.

The Spectrophotometric method was used to identify iodate by utilizing a class of antidepressants known as imipramine hydrochloride (IPH), desipramine hydrochloride (DPH), clomipramine hydrochloride (CPH), and trimipramine hydrochloride (TPM).

Iodate in nano amounts can be measured using this method in an acidic medium with 3-methyl-2-benzothiazolinone hydrazone hydrochloride hydrate (MBTH) acting as an electrophilic coupling reagent. The MBTH-IPH/DPH/CPH/TPM method had a blue with a maximum absorbance at 630 nm. Beer, 's law was followed, and the blue color that was produced remained stable for up to 24 hours at room temperature (27°C).

The boundaries depending on the situation for the assessment of the strategy like molar absorptivity and Sandell's sensitivity gave various qualities with various reagents. The method was tested with interference from common 11 cations and 8 anions, and the results obtained were within a reasonable range.

The procedure was used for the determination of iodate in iodized edible salts because iodate is one of the common ions in iodized salt. It was found that the method is reliable and can be used effectively for the determination.