Physical Chemistry Research
Volume:12 Issue: 1, Winter 2024

Green approach, organic solvents, modified aging and ambient pressure drying were followed to synthesize two type of silica aerogels (SGTEH-Iso and SGTEH-Sim). The gels were characterized using SEM, FTIR and BET. The results indicated that both the aerogels possessed remarkably decent properties with highly mesoporous structure. Such properties are significantly attributed to novel modified sol-gel aging method employed for each aerogel. The prepared silica aerogels were investigated for their Pb (II) removal from aqueous solution. Among the two aerogels, SGTEH-Iso performed better than SGTEH-Sim, which is a result of isolated aging with solvents versus simultaneous aging. When the results of the present study were compared to the similar previous studies, the removals by both the aerogels were enhanced and higher.

The world''s rising industrialization and motorization are to blame for the rise in demand for petroleum products. As a result, alternative fuels that can be made with locally available materials must be sought. Biodiesel is a liquid fuel similar to diesel that is created from biological sources that are renewable. Methyl esterification is a process that may turn any type of vegetable oil or animal fat into biodiesel, which is subsequently suitable for use in diesel engines. Our present investigations, aims to examine the difficulties in producing biodiesel from neem oil and to look into the characteristics of the fuel, which is fully made of mono alkyl esters produced by the transesterification process. For this experimental operation, a single cylinder, four-stroke, kirlosker diesel engine with a 1500 rpm, 3.72 kw brake power, 110 mm stroke length, 80 mm bore, and 17.5 compression ratio was used.At 1kg, 2.5kg, and 4kg loads and 2B, 3.5B, 5B, and 6B blends, the brake power efficiency, brake thermal efficiency, mechanical efficiency, specific fuel consumption, and emission characteristics were computed and examined. Biodiesel outshines diesel oil, according to the data.

Using plant bioresources to produce nanoparticles has emerged as a low-cost, eco-friendly process and an ethically sound way of protecting and preventing the environment from releasing toxic and hazardous substances associated with other synthetic methods. In this study, silver nanoparticles were prepared by using Chromolaena odorata leaf extract bio-reduction of silver nitrate. The bio-reduced nanoparticles were characterized by UV-Vis, FTIR, and SEM coupled with EDS. The effects of the volume ratio of plant extract to silver nitrate solution, time, and concentration were examined on the yields of the nanoparticles using a central composite factorial design and a response surface model. The FTIR spectrum of the synthesized silver nanoparticles showed the possible involvement of conjugated C-C and C-O-H groups in the bio-reduction process. The nanoparticles showed some antimicrobial properties against some tested pathogens. The nanoparticles appeared clustered and aggregated together in morphology. The optimum nanoparticle yields were obtained using low values of the ratio of plant extract to silver nitrate solution (1:1) and high values of time (45 minutes) and concentration of silver nitrate (3 mM), respectively. These are possible reaction conditions for maximizing nanoparticle yields from Chromolaena odorata leaves.

In the current study, the solubility of nicotinamide in all fractions (with 0.1 intervals) of acetonitrile and ethanol mixtures was gravimetrically determined. The results show that maximum solubility was obtained in ethanol mass fraction of 0.8 (xm=8.52×10-2) at 313.2 K and the minimum solubility in the pure acetonitrile (xm=7.33×10-3) at 293.2 K. In the next step, all data are fitted/back-calculated by several mathematical cosolvency equations. Deviation amount of back-calculated data from experimental values (<5.0%) shows the applicability of the models for the prediction of solubility. Also, density data for saturated systems are determined and fitted to the adopted form of the Jouyban-Acree model which obtained a back-calculated MRD% of 0.7%. Furthermore, the thermodynamic behavior of nicotinamide in investigated mixtures was investigated using the calculation of the Gibbs energy, enthalpy, and entropy at Thm. Further, inverse Kirkwood-Buff integrals calculations demonstrated preferential solvation of nicotinamide by acetonitrile in acetonitrile-rich solutions.

This study investigated the potential of Algerian kaolin clay exchanged with protons as an inexpensive adsorbent for malachite green (MG) dye elimination from colored effluents using batch equilibrium experiments. Before using the kaolin as an adsorbent, it was treated with HCl (0.1 M). The structural, compositional, and textural characteristics of the Tamazert kaolin (TK) and the treated Tamazert kaolin (tTK) were determined using physicochemical and mineralogical characterizations. The optimization of miscellaneous experimental parameters such as contact time, adsorbent dose, temperature, and initial pH solution was conducted through batch adsorption experiments. The findings of the experiment revealed that 30 minutes of contact time was adequate to achieve liquid-solid phase equilibrium. The highest adsorption capacity of MG dye was reached at 18.51 mg/g. The adsorption kinetics followed the pseudo-first-order model. The adsorption isotherms showed a correlation between the Freundlich model and the experimental results. Changes in enthalpy, Gibbs free energy and entropy were computed.

In this work, the retention of the acid blue113 (AB113) textile dye from synthetic dye solution by using cationic poly(n-hexadecyl-4-vinylpyridinium bromide) [P4VP-C16Br] was reported. The removal of anionic dye was ascribed to two different processes. The first concerns the batch adsorption experiments performed to investigate the experimental parameters effect on the AB113 adsorption equilibrium. Then, the adsorption characteristics of copolymer via acid blue 113 in dilute aqueous solution were studied by UV-Vis spectrophotometroy. Indeed, the adsorption equilibrium was reached within 3 h of poly(4-vinylpyridine) quaternized at 50% and the adsorption kinetics is best described by a pseudo-second-order model. Additionally, the equilibrium modeling of AB113 removal process was described by Langmuir isotherms. On the other hand, the second method was based on the flocculation process where use [P4VP-C16Br] as flocculant in its soluble form in acidic medium. Different parameters effecting the retention were studied as variable including pH of AB113; [P4VP-C16Br] dose, AB113 concentration and contact time between the copolymer and the used dye. At the optimal dose of [P4VP-C16Br] flocculant, the removal ratio of acid blue 113 could reach more than 98% in the pH range of 2-8. Furthermore, the flocculation process using [P4VP-C16Br] is a very fast process.

Hydroxyapatite/starch (HA/Star-n; « n » represents the weight ratio of HA to Star ) bio-composite was obtained by in situ chemical precipitation of calcium hydroxide using phosphoric acid in the presence of starch. Analysis through FTIR and XRD confirmed the formation of hydroxyapatite within the polymer matrix. To date, no work was reported in the literature concerning the use of composites based on hydroxyapatite and native starch as adsorbent in the treatment of wastewaters. For this, the elaborated HA/Star-n composite was used for the removal of methylene blue (MB) from aqueous solution through batch experiments. The effect of pH (2-12); contact time (5-180 min) and dye concentration (15-100 mg/L) was explored. The results prove that the optimum pH for MB removal by the bio-composite is pH= 6. Conversely, pure HA showed minimal removal efficiency at this pH. Further, kinetic study revealed that the adsorption of MB onto HA/Star-n is a rapid process described by pseudo-second order model. Results from the dye concentration study suggest that the adsorption efficiencies of the elaborated bio-composite can exceed 90% with an adsorption capacity of 45.51 mg/g demonstrating that HA/Star-n has a great potential as an adsorbent for the removal of MB from aqueous solution.

Polymeric-based dispersant plays a crucial role in stabilizing carbon particles in oil system, where their concentration and the viscosity of the bulk oil play an important role in carbon interactions. The model system used is able to produce neat fundamental understanding of the behaviour of carbon particles in oil, influenced by the concentration of polyisobutylene succinimide(PIBSI) dispersant. The surface charges of the carbon particles were calculated from the electrophoretic mobility measurement, and the aggregation behaviour was evaluated using the hydrodynamic particle size measurement via the Dynamic Light Scattering (DLS) instrument and UV-Vis absorption. Comparatively, the magnitude of carbon effective surface charge in decane system was higher than in hexane without any PIBSI. The trend reached into an agreement at high PIBSI concentrations, with decane systems having larger charge magnitude, and particles in hexane were leaning towards the zero charges. The DLS measurements revealed that large carbon aggregates formed at low PIBSI concentration for hexane system, where a contrasting finding was reported for decane system. The UV-Vis absorption spectra of carbon particles in the decane system discovered that the system with 5 wt.% of PIBSI had the highest absorption, where the peak of absorption spectra in hexane increases with PIBSI concentration.

With the help of quantum computational methods, the current study aims to analyze the geometric as well as spectroscopic studies on N, N-dimethyl-2-[6-methyl-2-(4-methylphenyl) imidazo[1,2-a]pyridin-3-yl] acetamide (zolpidem). The optimized structural characteristics, viz bond length and bond angles, were theoretically calculated and compared to experimental results. By using the DFT/B3LYP/6-311++G(d,p) basis set in IR and Raman studies, the existence of functional groups in the selected drug zolpidem has been further clarified, and the results were compared to experimental findings. The stretching vibration of the keto group was ascribed between 1649 cm-1 and 1637 cm-1. A three dimensional (3D) Hirshfeld surface (HS) and a two dimensional (2D) fingerprint map were analyzed to better understand how the compound molecules interact with one another. The results show that the interaction bond H•••H (60.1%) makes up the majority of the interaction. The charge distribution, intramolecular interactions, local reactive centers, and possible nucleophilic and electrophilic reactive sites were analyzed by Mulliken population, NBO and MESP analysis. Further, first order hyperpolarizability calculations have been carried out to determine the NLO of the titled compound. In-depth molecular docking simulation was performed to confirm the potential biological effects of zolpidem by establishing a binding pattern with orexin receptors.

This study investigated the optimization of regeneration of exhausted activated carbon (EAC) by hydrocarbons used in natural gas dehydration plants. Various methods were used including chemical, thermal, and steam regeneration. The experimental results demonstrated the effectiveness of steam regeneration of EAC at low temperatures, which was further enhanced by pre-regenerating EAC with dilute acid (2.5% hydrochloric acid). In addition, an evaluation of the regenerated activated carbon (RAC)’s performance against hydrocarbons from exhausted triethylene glycol (ETEG) was conducted using three parameters: the iodine number in EAC, the refractive index, and the density of triethylene glycol (TEG) regenerated for testing the adsorption capacity. The results showed that the adsorption capacity of RAC to hydrocarbons from ETEG increased with rising temperature, resulting in highly pure, hydrocarbon-free TEG suitable for use in natural gas TEG dehydration plants. The optimized steam regeneration method with dilute acid pre-treatment demonstrated significant potential for improving the efficiency and sustainability of natural gas dehydration processes. These findings have important implications for the design and operation of steam regeneration units in industrial settings. Moreover, this study contributes to the growing body of research on sustainable and cost-effective methods for hydrocarbon removal in the gas processing industry.

Alkaloid and Flavonoid extracts of Salvia Officinalis Leaves ( AESOL and FESOL) as eco-friendly corrosion inhibitors of 817M40T Mild Steel in 0.5 M Hydrochloric acid concentrated environment was carried out. Weight loss, Thermometric, electrochemical impedance spectroscopy and potentiodynamic polarization techniques were employed. The corrosion rate values of the alkaloid and flavonoid were seen to be in the decrease from 1.6 – 0.01 and 1.6 – 0.1 while the inhibition efficiency values were in the increase from 79.7 % - 99.3 % and 75.1 % - 93.8 % for alkaloid and flavonoid fractions respectively at concentrations of 150 – 1000 ppm which defined the inhibitors a good inhibitors. A slight effect of temperature on the inhibition process was observed from the thermometric result as temperature was increased owing to strong agitation of heat. Electrochemical data showed that charge transfer resistance and inhibition efficiency were increasing while double layer capacitance and corrosion current density values were decreasing with concentration. A mixed type inhibition was recorded while adsorption process proved that the inhibitors were a monolayer type and physically adsorbed. Thermodynamic data revealed an inhibitor that is stabled, spontaneous, associative and endothermic in reaction.

This study aimed to develop an electronic fuel injection system for utilizing ethanol as a fumigant in a single-cylinder, four-stroke, water-cooled diesel engine. The engine's emissions and performance were evaluated through experiments to determine the impact of ethanol fumigation. The main objective was to identify the optimal amount of ethanol that could reduce emissions while enhancing performance using a simple fumigation process. The tests were conducted at constant engine speeds and loads, with diesel fuel and ethanol flow rates ranging from 0.2737 to 0.958 kg/hr. The findings indicated that the most effective percentage of ethanol was 0.8767, resulting in the best outcomes. Additionally, the emissions of CO, HC, and NOx remained constant after reaching 21.69% thermal efficiency, indicating the optimal level of fumigation. To better understand the engine behavior observed, the theoretical aspects of diesel engine combustion were combined with the distinct physical and chemical properties of ethanol compared to those of diesel fuel.

The Kinetics of Ninhydrin (Nin) reaction with Ampicillin (Amp) has been studied in an aqueous acidic medium. The product of the reaction was examined spectroscopically using Nuclear magnetic resonance (1H-NMR) and Infrared spectra in addition to Ultra-performance liquid chromatography (UPLC). The reaction was monitored spectrophotometrically, with (0.1- 0.4) × 10-4 mol dm-3 of Amp, (0.5-5.0) ×10-2 mol dm-3 Nin and 0.3- 0.9 mol dm-3 ionic strength (I) over the (30-50) °C range of temperature. It is first order with respect to [Nin] and [Amp], decreases as pH increases in the range (4.70 -6.04). The effect of the catalyst on the rate of the reaction was studied. The thermodynamics activation parameters involving ∆H* and ∆S* have been calculated. The rate of the reaction follows the rate law d[Amp-Nin]/dt ={k2 + (k4+k3[H+])[Nin]}×[ Amp]. For this reaction is proposed mechanism was supported by an excellent isokinetic relationship between ∆H* and ∆S* for some Nin reactions. In emergency case when posing with Amp about 30% of the oral dose is excreted in urine in 6 hours as unchanged drug, so a presumptive colour test is necessary in clinical toxicology. Then, using Nin to form a coupling complex with Amp is an effective method.

In this paper, the preeminent perspective is to examine the flow of ElectroMagnetoHydroDynamic (EMHD) Casson nanofluid through a stretchable Riga plate with variable viscosity comparing two basic models, Reynolds and Vogel’s models. Brownian motion, thermophoresis and nonlinear thermal radiation is considered. Using appropriate transformations, The PDEs undergo a process of conversion to nonlinear (ODEs), and solved numerically with Bvp4c method. The main goal is to visualize the influence of some parameter, such as modified Hartman number (0.5 ≤ E* ≤ 1.5), Casson parameter (0.3 ≤ β≤ 1.1), dimensionless parameter (0.5 ≤ S ≤ 1.5), suction parameter (-0.5 ≤ fw ≤ 0.5), Prandtl number (1 ≤ Pr ≤ 10), radiation parameter (1 ≤ Rd ≤ 5), space-dependent heat source (0 ≤ Q ≤ 2), chemical reaction (0.5 ≤ γ1 ≤ 1.5), temperature-dependent heat source (0 ≤ Q* ≤ 2), Schmidt number (1 ≤ Sc ≤ 1.8) and Brownian motion (0.1 ≤ Nb ≤ 0.5) on Temperature and velocity profiles. The outcomes reveal that the modified number of Hartmann has a remarkable impact on the velocity profiles which leads to control the flow. In addition, the increment of radiation parameter causes to enhance the temperature.

Continuing the success of the researchers on ionic liquids application in biomedicine, lithium-sodium batteries, and chemical engineering, we try to investigate temperature, cation, and anion contribution in the most important thermodynamic parameters of the 33 metal containing ionic liquids. Critical parameters, density, thermal expansion coefficient, critical compressibility factor, surface tension, and lattice energy of studied systems carried out based on classical thermodynamic methods and compared by reported experimental data in the literature. Results revealed that 1-hexyl-3-methyl-imidazolium and tungsten hepta fluoride as anion show the higher contribution in Tb (boiling temperature), while hepta-chlorodialuminate and 1-hexyl-3-methyl-imidazolium as cation showed the main contribution in Vc (critical volume) respectively. Temperature dependence of density has been perfectly determined by the first-order polynomial and our proposed method in the present work. 3D graph of surface tension as a function of cation, and anion structure determined the anion group are found the important influence in surface tension at constant temperature due to the greater polarizability, the lower hydration, and consequently screening the electrostatic repulsion between IL head groups. Undoubtedly, the information provided in this research is an important help to scientists to choose the appropriate ionic liquid in specific conditions.

In this work, we developed an eco-friendly material to apply in the wastewater treatment operation. This copolymer was prepared from carboxymethylcellulose (CMC) modified with acrylamide (AM) and N-vinylpyrrolidone (NVP). It was characterized using FTIR spectrometry, Thermogravimetric Analysis (TGA/DTG) and diffraction of X-ray (XRD). CMC-AM-NVP copolymer properties as an adsorbent of methylene blue (MB) dye were investigated. Influencing parameters on the removal process were also studied. It was found that the adsorption of MB dye on CMC-AM-NVP copolymer can be described by the pseudo-second order equation. Equilibrium data was modeled by Langmuir, Freundlich, and Temkin isotherms. Langmuir isotherm model provides the best fit to represent the adsorption of MB on the CMC-AM-NVP copolymer within R2 equal 0.999. The dye elimination efficiency on the copolymer reached 99.4%. According to these tests, CMC-AM-NVP was found to be promising candidates for efficient removal of methylene blue; therefore, we can conclude that the addition of NVP to the copolymer has a clear improvement in the adsorption process.

Hydrochloric acid (HCl) is a substance that is frequently utilized in industrial operations for important tasks such as chemical cleaning and pickling metallic surfaces.Therefore, the corrosion inhibition ability of three newly synthesized quinazoline derivatives namely, 3-allyl-2-(propylthio) quinazolin-4(3H)-one) (APQ), (3-allyl-2-(allylthio) quinazolin-4(3H)-one) (AAQ), (3-allyl- 2-( Prop -2-yn -1-ylthio) Quinazolin - 4 (3H) - one) (AYQ) were theoretically determined and these compounds were characterized using Fourier Transform Infra-Red (FTIR) and 1H and 13C Nuclear Magnetic Resonance (NMR) spectroscopic. A series of quantum chemical properties of these derivatives: EHOMO, ELUMO, energy gap (ΔE),dipole moment (μ), hardness (η), softness (Ϭ), absolute electronegativity (χ), fractions for electron transferred (ΔN), the ionization potential (I), (TE) and total energy were calculated. The obtained results of all quinazoline derivatives (APQ,AAQ,andAYQ) show almost the same corrosion inhibition with excellent efficiency. Density function theory (DFT) was used to investigate the relationship between the molecular structures and inhibitory efficacies of three quinazoline derivatives. The results of the analysis and measurement of Egap values revealed that the compound AYQ had a modest Egap of 4.999 eV and that strong values of Egap suggest that it will be easier to remove one electron from the HOMO orbital and deposit it in the LUMO orbital

In the present work, silica aerogel was surface modified using mercaptopropyl trimethoxysilane (MPTMS). The synthesized aerogel was characterized using FTIR, TGA and BET. The modified silica aerogel was investigated for Pb (II) removal from aqueous solution via pH, metal concentration and adsorbent dose experiments. As per results, the respective aerogel performed excellent with maximum adsorption capacity (qm) of 240 mg/g. This was compared with 14 other relevant studies where this work stood second highest indicating significantly higher qm than Organic Ligand, AFSG, Diethylenetriaminopropyl, Ethylenediaminopropyl, Ethylenediaminopropyl, Aminopropyl, PEI, AAAPTS, rGO, Thiamine, bispyrazole, DETA and 2-furoyl functionalized silica gels. When the isotherm studies were conduction, the adsorption data best fitted Freundlich isotherms with R2 value of 0.99.

The current research was designed to provide a theoretical approach for the selection of the optimum coagulant to remove Reactive Black-5 dye from industrial waste. Additionally, it seeks to identify the dye's most reactive sites and understand its degradation in water pollution. Theoretically, the study was investigated using the density functional theory (DFT) with a 6-31G (d) basis set. The studied molecules are the reactive Black-5 dye, ferric sulphate (Fe2(SO4)3), ferric chloride (FeCl3), aluminium sulphate (Al2(SO4)3), and aluminium chloride (AlCl3). Based on the electrophilicity index, the results revealed the following classification: Fe2(SO4)3 > FeCl3 > Al2(SO4)3 > AlCl3. Thus, Fe2(SO4)3 acts as an electrophile, and the Reactive (RB5) as a nucleophile. The Parr index analysis of the dye studied indicates that the most vulnerable region for the nucleophilic attack is sited on the C5-9H bonding area with ω_k=2.797 eV. The results of the experiments match well with the reported theoretical data, with the coagulant Fe2(SO4)3 achieving the highest Chemical Oxygen Demand removal rate (84.71% at pH = 4). To support the findings, we provide an experimental investigation using the coagulation-flocculation method for these various coagulants to remove the reactive Black-5 dye from industrial effluents.

In this work, a number of 2-acetylphenol-rivastigmine hybrids have been rationally created as drugs for the treatment of behavioral disorders, especially depression. On a series of inhibitors that are 2-acetylphenol-rivastigmine hybrids, we have used virtual in silico screening techniques such as Three-dimensional QSAR, molecular docking, and pharmacokinetic properties (absorption, distribution, metabolism, excretion, and toxicity (ADMET) techniques. The aim of this study was to obtain new ligands with high inhibitory activities. The best 3D-QSAR model was created using the PLS approach and comparative molecular similarity index analysis (CoMSIA), which demonstrated strong correlative and predictive capabilities (r2 = 0.904, q2 = 0.699 and SEE = 0.094). The change of biological activity with four main components is significantly influenced by the steric, electrostatic, hydrophobic, and H-bond acceptor fields. Using these acceptable results, new molecules were developed and analyzed using in silico drug similarity, ADMET and molecular docking.