Band 237, Heft 6

The purpose of this study is to introduce and develop a new experimental method based on UV spectroscopy for measuring the degree of substitution (DS) of phthaloyl group used for protecting amine group in chitosan, a biopolymer derived from chitin that has a wide variety of applications including drug delivery in pharmaceutical products. N-phthaloylated chitosan was synthesized and the UV absorption measurements were performed on its solutions with different DS with concentrations of 6.25, 12.5, 25, 50, and 100 μg/mL in DMSO at 295 nm. The accuracy of the method was checked with H-NMR and there was consistency between the results obtained by two methods. This suggests that the UV spectroscopy can be a potential method for the characterization of the polymer and can replace the difficult methods of analysis used for the chemical structure.

Biogenic green synthesis of gold nanoparticles (Au-NPs) was carried out by utilizing fated waste product of sugarcane industry. Sugarcane bagasse extract was obtained by constant stirring of sugarcane bagasse in aqueous medium for 20 min. Synthesis of gold nanoparticles was carried out at different values of pH of the medium in order to determine the effect of pH on the formation of gold nanoparticles. Fabrication of gold nanoparticles was confirmed by UV–Vis spectroscopic analysis of the reaction mixture and XRD analysis of the sample. FTIR was used to identify different functionalities present in extract responsible for the formation of gold nanoparticles. Biogenic Au-NPs were utilized as a catalyst for the reduction/degradation of nitroarenes and organic dyes such as 4-nitrophenol (4-NP), 4-nitroaniline (4-NA), Congo red (CR), methyl red (MR), brilliant blue (BB), rhodamine B (Rh B) and methyl orange (MO). Kinetics of these reactions proves the efficiency and effectiveness of sugarcane bagasse mediated gold nano-catalysts making them an excellent tool for industrial applications.

The study focusses on the ecofriendly synthesis of copper oxide nanoparticles (CuO NPs) using aqueous extract of Chenopodium album leaves. The prepared NPs were characterized using techniques such as Fourier transform-infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX). UV–Vis spectroscopy exhibited absorption maximum ( λ max ) at 271 nm for CuO NPs. The average size of crystallite was observed as 17 ± 3 nm using XRD. SEM illustrated that the shape of fabricated NPs was spherical. Elemental composition was further supported by EDX. The photocatalytic nature of prepared NPs was assessed by degradation of atrazine and abamectin. Maximum degradation 53.61 % and 57 % of abamectin and atrazine was observed in presence of these particles after the 180 min exposure time. The pesticides removal followed the zero-order kinetics. It may be concluded that CuO NPs synthesized from C. album could behave as suitable candidate for the degradation of toxic pollutants in wastewater.

Despite corrosion being an inevitable process, researchers strive to control corrosion. In this study, our goal was to prepare two amido Gemini cationic surfactants, LAPG and MAPG, each with different alkyl chains and multiple carbonyl groups as rich electronic rich centers. We aimed to evaluate these surfactants as potential corrosion inhibitors for carbon steel (CS) in 1 M HCl at temperatures of 25–55 ± 0.1 °C. In theoretical investigations, DFT parameters and Mont Carlo simulation were run to predict the adsorption affinity and reactive sites of the LAPG and MAPG molecules. Their efficacy was investigated experimentally considering weight loss and electrochemical techniques. The Tafel polarization revealed that at 0.1 mM of LAPG and MAPG, the corrosion current density ( i corr ) of CS was reduced to the lowest extent (75.56 and 53.82 μA cm −2 ) compared to 529.3 μA cm −2 in the absence of the inhibitors. EIS data suggests the enhancement of the thickness of the adsorbed layers of the studied compounds from the decrease of the double-layer capacitance C dl values. The Langmuir isotherm explained the adoption phenomena of these compounds at 25–55 ± 0.1 °C. Activation and adsorption thermodynamic parameters predicted the chemisorption behavior of these molecules onto the steel surface. AFM and XPS tools confirm the CS surface protection due to these inhibitors’ adsorbed layer. A parallel study showed the superiority of these corrosion inhibitors in HCl compared with those reported earlier, making these compounds highly promising corrosion inhibitors, especially in high-temperature acidic environments.

For three-dimensional multi-layer molecularly thin-film lubrication system with elastic substrates, roles of hysteresis on tribological properties are investigated by using the multiscale simulation method. It is found that multiple stick-slip transitions with/without hysteresis loops appear in a sliding process and form a quasi-periodic progress with lattice distance. For the few-/multi-layer thin-film lubrication system, as the load increases, the hysteresis length monotonously increases/tends to keep constant. The hysteresis is mainly caused by the relaxation of metastable states of solid atoms in the elastic substrates, which delays the system back to its equilibrium states. In the quasi-periodic shearing progress, the effective elastic coefficients and the hysteresis lengths approximately remain unchanged, which reveals that although the hysteresis loops with the same lengths appear in the sliding process, the total systematic energy is still conserved. These findings not only provide a profound understanding of roles of hysteresis in the thin-film lubrication system but also show the effects of film layers and loads on the systematic tribological properties, which are of great significance for practical applications.

Alkaline earth metal salts and citric acid both play a vital role in our daily life in terms of biological importance, so in this regard, in the present study, we calculated density, speed of sound, conductance and viscosity of barium chloride (BaCl 2 ) in concentration range (0.01–0.12 mol kg −1 ) in a binary solution of 0.01 mol kg −1 citric acid in water (CA + H 2 O) at temperatures between 303.15 and 318.15 K with gap of 5 K. The various parameters like apparent molar volume ϕ v , limiting apparent molar volume ϕ v o , transfer volume Δ tr ϕ v o , and partial molar volume expansibilities Φ E o ${{\Phi }}_{E}^{o}$ were calculated using density data. Viscosity data has been applied to calculate relative viscosity and Jones Dole coefficient A and B. Other parameters like Molar conductance (Λ m ), Λ o m and Λ o m η o have also been calculated using conductance data. All these parameters show strong evidences of various molecular interactions in terms of ion–solvent and solute–solute interactions. The ion–solvent interactions were supported by isobaric thermal expansion coefficient α o . Structure maker/breaker behaviour is explained by Hepler’s constant (( d 2 ϕ v o / dT 2 ) p ), temperature coefficient of B ( d B / d T $dB/dT$ ) and Walden product’s temperature coefficient ( d (Λ o m η o )/ dT ). Further these molecular interactions support structure breaking potential of present studied system.

Bis ethoxylated cationic surfactant (BOECS) is synthesized. The prepared surfactant’s structure configuration was verified through a variety of spectral and physicochemical techniques, including FT-IR, MS, 1 HNMR, and surface activity evaluations. BOECS applications as a C-steel corrosion inhibitor in 1.0 N HCl and 1.0 N H 2 SO 4 and sulfate reducing bacteria (SRB) mitigations have been investigated thoroughly. Physical properties of the BOECS indicate its potential adsorption affinity at the air/water interface. The electrical conductivity determines the CMC value in accordance with the surface tension value. Electrochemical kinetic parameters indicate the BOECS is sorted as a mixed-type inhibitor and has an inhibition efficacy of 91.22 % and 81.26% for HCl and H 2 SO 4 , respectively. Active centers of BOECS structure enhance its adsorption at the electrolyte/C-steel. Calculated adsorption energy change ( ∆G ads ) and theoretical adsorption energy ( E ads ) values suggest strong and spontaneous BOECS adsorption. The cytotoxic performance of the synthesized BOECS exhibited a potent inhibitory potential against the SRB. The outcomes of this research exhibit that the BOECS can lower SRB growth from 10 6 to 10 2  cell/mL.