Thermodynamic Investigation Research Articles

Thermodynamic characteristics and surface free energy analysis of bifonazole and lecithin with sodium dodecyl sulfate in hydroethanolic solvent systems

The thermodynamic investigations of the well-recognised antifungal drug bifonazole and lecithin with anionic surfactant sodium dodecyl sulphate have been established. The experiments were conducted using five distinct hydro-ethanolic concentrations, namely 0% v/v, 10% v/v, 30% v/v, 70% v/v, and 90% v/v ethanol, throughout a range of five temperatures (ranging 20 ℃, 25 ℃, 30 ℃, 35 ℃ and 40 ℃) with an increment of drug concentration. The study involved the determination of several parameters, including surface tension (σ), density (ρ), conductivity (κ), contact angle (θ) and surface free energy. Conductivity and surface tension data was used for calculating critical micelle concentration (CMC). CMC was utilised to calculate various thermodynamic properties, such as the standard entropy change (ΔS°m), standard Gibbs energy change (ΔG°m) and standard enthalpy change (ΔH°m) of micellization. This study represents a comparative analysis of the critical micelle concentration (CMC) by utilising surface tension and conductivity measurements. Contact angle is used to determine the hydrophobicity and hydrophilicity of the system. These investigations are valuable for examining the magnitude of hydrophobic interactions within the system, which might be used to ascertain an optimal concentration of bifonazole, lecithin and surfactant to prepare ethosomal formulations.

The Development of One New Normal Phase Liquid Chromatography Method and Thermodynamic Investigation of Olodaterol Hydrochloride Enantiomer.

In order to improve and replace the enantiomer method outlined in the olodaterol hydrochloride draft monograph (From the European Pharmacopoeia forum), one new, simple, and fast enantioselective normal phase high-performance liquid chromatography chiral method was developed on polysaccharide-based Chiral MX (2) (4.6 × 250 mm, 5 μm) column. n-Hexane, ethanol, and diethylamine in the ratio of 40:60:0.1 (V/V/V) were selected as mobile phase at a flow rate of 0.8 mL/min, and the detection was performed on a photodiode array detector at 225 nm with 5 μL injection volume. The column temperature was set at 40°C for better peak shape and sensitivity. The analysis time can be shortened to 15 min, whereas the resolution between enantiomer and olodaterol was found to be even more than 10.0, which was far better than that obtained with the reported method in this draft monograph. The developed chiral method was validated in accordance with ICH Q2 (R1), including specificity, LOD&LOQ, precision, linearity, accuracy, and robustness. Thereby, the proposed method was demonstrated to be suitable for the determination of enantiomer inolodaterol hydrochloride bulk drug and drug product. Besides, the thermodynamic parameters were evaluated on the basis of Van't Hoff plots that was used to explain correlative chiral recognition mechanisms with the chiral stationary phase.

The Fate of Fluorine Post Per- and Polyfluoroalkyl Substances Destruction during the Thermal Treatment of Biosolids: A Thermodynamic Study

Per- and polyfluoroalkyl substances (PFAS) are a group of fluorinated synthetic chemicals that are highly recalcitrant, toxic, and bio-accumulative and have been detected in biosolids worldwide, posing potential risks to humans and the environment. Recent studies suggest that the organic C-F bond in PFAS can be destructed and potentially mineralised into inorganic fluorides during thermal treatment. This study focuses on thermodynamic equilibrium investigations and the fate of fluorine compounds post-PFAS destruction during biosolid thermal treatment. The results indicate that gas-phase fluorine compounds are mainly hydrogen fluoride (HF) and alkali fluorides, whereas solid-phase fluorine compounds include alkaline earth fluorides and their spinels. High moisture and oxygen content in the volatiles increased the concentration of HF in the gas phase. However, adding minerals reduced the emission of HF in the gas phase significantly and enhanced the capture of fluorine as CaF2 spinel in the solid phase. This study also investigates the effect of feedstock composition on the fate of fluorine. High ash content and low volatile matter in the feedstock reduced HF gas emissions and increased fluorine capture in the solid product. The findings of this work are useful in designing thermal systems with optimised operating conditions for minimising the release of fluorinated species during the thermal treatment of PFAS-containing biosolids.

Fabrication of Nanocellulose/Chitosan Nanocomposite Based on Loofah Sponge for Efficient Removal of Methylene Blue: Thermodynamic and Kinetic Investigations

AbstractWe established three nano-solid adsorbents: nanocellulose based on plant loofah sponge (NC), chitosan (CS), and nanocellulose/chitosan composite (CSC). These substances were employed as solid adsorbents to eliminate methylene blue (MB) dye from wastewater. Various characterization techniques were employed to investigate all the synthesized solid adsorbents, including TGA (thermogravimetric analysis), XRD (X-ray diffraction spectra), (BET) nitrogen gas adsorption-desorption, SEM (scanning electron microscope), TEM (transmission electron microscopy), FTIR (Fourier transform infrared) spectrometer, and zeta potential. According to our results, CSC showed greater thermal stability than LS and NC but lower than CS, mesoporous (2.012 nm), higher total pore volume (0.366 cm3. g− 1), specific surface area (639.3 m2. g− 1), and pHpzc of 7.22. The static adsorption of MB was well described by the Langmuir (R2 > 0.9872), Temkin (R2 > 0.9668), and Dubinin-Radushkevich (R2 > 0.9485) models. The composite of nanocellulose and chitosan exhibited the highest Langmuir adsorption capacity (301.20 mg. g− 1) at 47 °C after a 24 h shaking period at a dosage of 2 g. L− 1 as the adsorbent and pH of 7. The adsorption of MB by the fabricated solid materials fitted well with the linear PSO (R2 > 0.9806) and Elovich (R2 > 0.9574) kinetic model. The enthalpy, entropy, and free energy change for the adsorption of MB onto CSC were determined to be 47.11 kJ. mol− 1, 0.172 kJ. mol− 1. K− 1, and − 3.29 kJ. mol− 1, respectively at 20 °C. Thermodynamic investigation showed that MB adsorption is spontaneous, endothermic, favorable (0 < RL<1, 0.017–0.313), and physisorption (EDR < 8 kJ. mol− 1). Compared to the other eluents, nitric acid produced the highest desorption percentage (98.5%).

Thermodynamic and surface active investigations of aqueous solution of sodium dodecylbenzene sulfonate in presence of builders: sequestration of Ca2+ ions and interaction with H2O2

Abstract The current investigation examines the micellization process of sodium dodecylbenzene sulfonate in aqueous media with builders at temperatures ranging from 298.15 K to 313.15 K. Using conductometry and tensiometry analyses, the study examines changes in micellar properties in different surfactant solutions, focusing primarily on CMC. Additionally, the variation of CMC with temperature was used to determine the thermodynamic parameters of micellization such as ∆ G m ° , Δ H m ° , ${{\increment}G}_{\mathrm{m}}^{{}^{\circ}},{\Delta }{H}_{\mathrm{m}}^{{}^{\circ}}\text{,}$ and ∆ S m ° ${{\increment}S}_{\mathrm{m}}^{{}^{\circ}}$ . This approach provides valuable insights into the behavior of the surfactant and the different intermolecular interactions involved in the system. The different surface active parameters π CMC, A min, and Γ max were elucidated using tensiometry via the Wilhelmy plate technique. Moreover, the capacity of the builder to sequester calcium ions was studied using a well-established titration method, offering valuable insights into their effectiveness. Their efficiency under oxidative conditions, particularly in preventing the interaction between copper ions and hydrogen peroxide, was evaluated. This article provides a comprehensive analysis of different builders when used with the anionic surfactant, sodium dodecylbenzene sulfonate. Their combination provides improved efficiency in protecting metals from corrosion, extracting heavy metals from polluted soils, and in personal care products such as shampoos and soaps.

Thermodynamic study of zeolite and graphene nanoplatelet-based composites for adsorption cooling systems

The consolidated composite adsorbents containing AQSOA-Z02 zeolite and graphene nanoplatelets (GNPs), recently developed and exhibiting excellent thermophysical and water adsorption characteristics, are found to overcome the above-mentioned limiting factors. However, rigorous thermodynamic analysis has not yet been studied, which is crucial in the simulation of adsorption characteristics, system design, and ACS analysis. Therefore, this study aims to conduct a rigorous thermodynamic investigation and the assessment of performance parameters for various AQSOA-Z02 – GNPs–based composite/water pairs. In the thermodynamic analysis, the heat of adsorption (Qst) and the adsorbed phase-specific heat capacity (cp,a) are investigated theoretically. The study reveals that Qst decreases with adsorption uptake, while cp,a exhibits the opposite trend. The incorporation of H25-GNPs into zeolite leads to a reduction in both Qst and cp,a, contributing favorably to the design of an energy-efficient ACS. Additionally, the performance parameters such as specific cooling effect (SCE) and coefficient of performance (COP) are theoretically investigated with variations in desorption and evaporation temperatures. Both SCE and COP increase with evaporation and desorption temperatures. The composite containing 90 wt% AQSOA-Z02 and 10 wt% H25-GNPs exhibit the maximum COP value of 0.351 and the maximum volumetric cooling effect of 581.621 MJ m−3, which are almost 20% and 41% improvement over parent AQSOA-Z02 zeolite, respectively. All the findings of this study will greatly assist in the design of an energy-saving and eco-friendly adsorption cooling system.

Optical and thermodynamic investigation of jet-guided spark ignited hydrogen combustion

Hydrogen as an alternative fuel for engines is gaining interest to decarbonize the heavy-duty sector. Hydrogen combustion in engines conventionally relies on the Otto cycle and either port fuel or direct injection. This combustion concept usually results in poor power density and non-ideal efficiencies due to the lean premixed operation and low compression ratio required to avoid preignition and knocking. In this study, hydrogen is directly injected at high pressures into the combustion chamber and spark-ignited with two different ignition systems (inductive and nanosecond repetitively pulsed discharge) at the periphery of the jet, with fuel conversion taking place predominantly in jet-guided (diffusion) mode while injection remains active.A rapid compression expansion machine (RCEM) is used to investigate the jet-guided hydrogen combustion thermodynamically and optically by combining high-speed Schlieren and OH* chemiluminescence imaging, and spark-induced breakdown spectroscopy (SIBS).SIBS reveals low air to fuel ratios at ignition time and location, ranging from 2.8 up to pure air depending on the condition and significant variation among repetitions. Both OH* chemiluminescence and Schlieren images illustrate how air entrainment pushes the flame-plasma kernel from the ignition location at the periphery of the jet towards the fuel-richer core, resulting in fast combustion of the already premixed fuel. Subsequently, the combustion process becomes dominated by the mixing dynamics. Under conditions of low in-cylinder pressures, the Heat Release Rate (HRR) closely follows the injected mass flow rate multiplied by the lower heating value of hydrogen, i.e., the combustion is mixing controlled. However, as the cylinder pressure increases, the mixing and combustion rates fall below the injected mass flow until lower densities are reached again.The delay between the start of injection and ignition primarily impacts the premixed peak, but the in-cylinder pressure and ignition source also play significant roles. This distinctive combustion process shows essential similarities to compression ignition Diesel combustion. The process holds the potential to achieve high efficiency, as hydrogen can be burned using process parameters typical of Diesel combustion without facing the constraints of knock or preignition and a complete absence of soot.

Comprehensive batch studies on removal of fluoride from aqueous solution by acid and alkali-activated adsorbents prepared from Dal lake weeds: Mechanism, Kinetics and Thermodynamics

An efficient and economical way of eliminating fluoride from water is being investigated by employing the buoyant aquatic plant (Dal weed). Two post-pyrolysis chemical activation alteration techniques were implemented: acidic activation by employing sulfuric acid (H-activation) and alkaline activation using sodium hydroxide (OH-activation). The batch kinetic studies have been carried out considering varying starting fluoride levels such as 2–10 mg/L. The impact of diverse procedural factors, including dosage of Dal weed, starting fluoride level, pH and contact duration was observed to determine their influence on fluoride adsorption kinetics. Based on analyzed exploratory results, removal efficacy of 63% for the OH-activated carbon and 83% for H-activated carbon was achieved at commencing fluoride level of 10 mg/L, adsorbent dosage of 0.8 g, at 25 °C after 120 min. The maximal fluoride uptake capacity for H-activated carbon was observed to be 78.158 mg/g. Kinetic investigations showed that the Freundlich isotherm model provided a satisfactory match with an R2 value of 0.99. The reaction order nature adhered to kinetics resembling pseudo second order. Thermodynamic investigation revealed endothermic sorption, with negative ΔG indicating spontaneous fluoride uptake. In comparison, the positive number for ΔS suggested random behavior at the contact involving the adsorbent and adsorbate. The investigations into the regeneration capabilities of the adsorbent material revealed that even after undergoing for five consecutive cycles of adsorption and regeneration, the adsorbent exhibited an uptake potential of 45%. The presence of competing ions in the solution negatively impacted defluoridation efficacy, with the influence following the order of HCO3−< NO3−< Cl−< SO42−< PO43−.

Electrochemical, thermodynamic and computational investigation of the use of an expired drug as a sustainable corrosion inhibitor for copper in 0.5 M H2SO4

Inappropriate disposal of unwanted, damaged, or expired medications poses a significant environmental threat, prompting scientists to look for greener solutions. Repurposing these medications as corrosion inhibitors is a viable strategy that has been investigated in the instance of the anti-inflammatory medication Fenoprofen (PPPA). Experiments on electrochemistry and weight loss showed that PPPA is a more potent corrosion inhibitor for copper in sulphuric acid solution than other medications. Higher concentrations of PPPA were found to increase polarization resistance and decrease double-layer capacitance, respectively, according to the results of electrochemical impedance spectroscopy, suggesting that PPPA can prevent copper from corroding. In addition, PPPA acts as a mixed-type inhibitor, affecting both anodic and cathodic processes. Thermodynamic and activation analyses confirmed the physico-chemical adsorption of PPPA on the metal surface, forming a protective barrier against acid attack. Experimental and computational results corroborate each other, underlining PPPA's potential as an effective and environmentally-friendly corrosion inhibitor.

Binary solid wastes derived clinker: Raw feed system design validation and thermodynamic simulation investigation

Solid waste derived clinker design methodology was established based on thermodynamic simulation and experiment validation via the recycling of incinerated sewage sludge ash (ISSA) and recycled concrete fine (RCF). Compared with 1000 °C and 1100 °C, 1200 °C was the optimum temperature for C2S-rich clinker synthesis due to the highest simulated belite content after sintering. A utilization rate of 95 % was achieved, accomplishing the maximization of solid waste recycling. Due to the CaCO3 phase formation by the reaction of high-content belite (46.8 %) with CO2, carbonated 1200ARS eco-cement showed higher compressive strength than OPC and other eco-cements. The lowest porosity (18.1 %) with dense microstructure was also obtained by carbonated 1200ARS. Benefiting from the high CO2 reactivity of belite, 1200ARS displayed the optimum CO2 sequestration capacity with a higher carbonation degree (30.1 %) than other batches, providing a promising direction for future development of the low-carbon cement industry to achieve environmental sustainability.

Converting CO2 Into Natural Gas Within the Autoclave: A Kinetic Study on Hydrogenation of Carbonates in Aqueous Solution.

Catalytic conversion of carbon dioxide (CO2) into value-added chemicals is of pivotal importance, well the cost of capturing CO2 from dilute atmosphere is super challenge. One promising strategy is combining the adsorption and transformation at one step, such as applying alkali solution that could selectively reduce carbonate (CO3 2-) as consequences of CO2 adsorption. Due to complexity of this system, the mechanistic details on controlling the hydrogenation have not been investigated in depth. Herein, Ru/TiO2 catalyst was applied as a probe to elucidate the mechanism of CO3 2- activation, in which with thermodynamic and kinetic investigations, a compact Langmuir-Hinshelwood reaction model was established which suggests that the overall rate of CO3 2- hydrogenation was controlled by a specific C-O bond rupture elementary step within HCOO- and the Ru surface was mainly covered by CO3 2- or HCOO- at independent conditions. This assumption was further supported by negligible kinetic isotope effects (kH/kD≈1), similarity on reaction barriers of CO3 2- and HCOO- hydrogenation (ΔH≠ hydr,Na2CO3 and ΔH≠ hydr,HCOONa) and a non-variation of entropy (ΔS≠ hydr≈0). More interestingly, the alkalinity of the solution is certainly like a two sides in a sword and could facilitate the adsorption of CO2 while hold back catalysis during CO3 2- hydrogenation.

Enhanced adsorption of lead (II) ions onto cellulose nanoparticles/chitosan composite based on loofah sponge: kinetic and thermodynamic studies

AbstractThe purpose of this work is to study the efficiency of lead ions removal via adsorption onto created solid nanomaterials. Three solid adsorbents were synthesized as cellulose nanoparticles (CN) extracted from plant loofah sponge using alkali treatment and acid hydrolysis techniques, chitosan beads (CZ), and cellulose nanoparticles/chitosan beads composite (CZC). The generated solid adsorbents were investigated using TGA, N2 adsorption/desorption, ATR-FTIR spectroscopy, SEM, TEM, XRD, and pHPZC. Based on our findings, CZC had a pHPZC of 7.2, a larger specific surface area (645.3 m2/g), and a total pore volume (0.372 cm3/g). The batch adsorption of lead ions was well-fitted by pseudo-second order, Elovich, Langmuir, Temkin, and Dubinin-Radushkevich on all the samples. Cellulose nanoparticles/chitosan composite had the highest Langmuir adsorption capacity (221.104 mg/g) at 47°C, 120 min as shaking time, 2 g/L as adsorbent dose, and pH 6.5. Nitric acid had the highest desorption percentage (92%). The thermodynamic investigation revealed that lead ion adsorption is endothermic, favorable, spontaneous, and physisorption. Our findings showed that CZC has a high adsorption capacity and rapid kinetics, indicating its potential for employment in water treatment.

Efficient removal of organic pollutants from aqueous environments using activated carbon derived from biomass waste of Calotropis procera fruit: Characterization, kinetics, isotherm, and thermodynamic investigation

In this research, a powder derived from the biomass of the Calotropis Procera fruit (FCP) was utilized to produce an activated carbon (AC). The H3PO4 was the activator agent. After the adsorption test, the AC (AC-FCP1–1) impregnated with a ratio of 1:1 was chosen as the most suitable and efficient for methylene blue (MB) removal in aqueous environments at high rates. The characterization of AC-FCP1–1 and its efficient adsorption of MB was confirmed through various methods and analyses. The SEM image shows and confirms the micropores and mesopores. EDX analysis reveals the elemental composition and then BET analysis using N2 at 77 K indicates a high surface area of 1025.0628 m2.g-1 and prominent microporosity. FT-IR analysis confirmed functional groups such as OH, CO, CH (aromatic), phosphorus bands, and CO bonds. The amorphous structure was confirmed by XRD analysis. Conversely, the batch study, adsorption modeling, and adsorption mechanism were also carried out. The Adsorption of MB onto AC-FCP1–1 follows a pseudo-second-order kinetic and Freundlich isotherm, indicating that the adsorption process of MB onto AC-FCP1–1 was performed in a multilayer with a physisorption process. The interactions between AC and MB were fast, irreversible, and favorable. The thermodynamic parameters show that this adsorption is exothermic. At equilibrium, under optimal conditions, the adsorption rate of MB onto AC-FCP1–1 reaches 99.24 % with a maximum adsorption capacity of 158.98 mg.g−1.

Electrochemical, Structural and Thermodynamic Investigations of Methanolic Parsley Extract as a Green Corrosion Inhibitor for C37 Steel in HCl

Phytochemical-rich natural extracts have recently attracted intense attention as green corrosion inhibitors and costly benign coating components for the protection of metallic structures of immense commercial importance. Herein, various methods were applied to assess the corrosion protection efficiency of a methanolic extract of parsley (Petroselinum crispum) (PCE) on carbon steel C37 in 1 M HCl. Initially, the chemical profile of PCE was analyzed using gas chromatography/mass spectrometry (GC/MS), and myristicin and apiol were identified as the main components. The results from the weight loss, electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization (PDP) techniques revealed a substantial reduction in the corrosion rate upon the use of PCE, with a maximum inhibition efficiency of 92% at 1 g L−1 PCE. To optimize the performance, the corrosion behavior was investigated over a temperature range of 303–333 K and for concentrations of 0.1–1 g L−1. The inhibition effectiveness increased at higher concentrations of PCE, whilst it decreased when the temperature was elevated. The query suggests that the adsorption process involves both physical and chemical mechanisms. The adsorption of PCE onto C37 was well described by the Langmuir adsorption isotherm. The data were used to determine the activation energy and thermodynamic parameters. The PCE coating acted as a mixed-type inhibitor, hampering both cathodic and anodic corrosion reactions. SEM further confirmed the formation of a protective coating film on the steel surface when exposed to PCE. UV-Vis and XRD were implemented to understand the inhibition mechanism and formed products at the microscopic and spectroscopic levels. Hence, the green PCE inhibitor may potentially be applied in corrosion mitigation due to its high corrosion protection efficacy and its environmentally benign nature.

Ultra-Rapid Electrocatalytic H2O2 Fabrication over Mono-Species and High-Density Polypyrrolic-N Sites.

Electrocatalytic hydrogen peroxide (H2O2) production via two-electron oxygen reduction reaction (2e--ORR) features energy-saving and eco-friendly characteristics, making it a promising alternative to the anthraquinone oxidation process. However, the common existence of numerous 2e--ORR-inactive sites/species on electrocatalysts tends to catalyze side reactions, especially under low potentials, which compromises energy efficiency and limits H2O2 yield. Addressing this, a high surface density of mono-species pyrrolic nitrogen configurations is formed over a polypyrrole@carbon nanotube composite. Thermodynamic and kinetic calculation and experimental investigation collaboratively confirm that these densely distributed and highly selective active sites effectively promote high-rate 2e--ORR electrocatalysis and inhibit side reactions over a wide potential range. Consequently, an ultra-high and stable H2O2 yield of up to 67.9/51.2molg-1h-1 has been achieved on this material at a current density of 200/120mAcm-1, corresponding Faradaic efficiency of 72.8/91.5%. A maximum H2O2 concentration of 13.47gL-1 can be accumulated at a current density of 80mAcm-1 with satisfactory stability. The strategy of surface active site densification thus provides a promising and universal avenue toward designing highly active and efficient electrocatalysts for 2e--ORR as well as a series of other similar electrochemical processes.

Two-phase separation facilitating the ordering of L10-FePt: experimental and thermodynamic investigation on Fe–Pt–Cu phase diagrams

The L10-FePt nanocrystals exhibit unique magnetic and catalytic properties, but suffer from the ordering difficulty. The addition of Cu can facilitate the L10-FePt ordering for some Fe–Pt–Cu alloys, however, the action mechanism is far from being well understood. In this work, a systematic study has been performed to the phase diagrams of the Fe–Pt–Cu system. The isothermal sections at 600 °C, 750 °C and 1000 °C, as well as the partial vertical sections of Fe50Pt50–Cu50Pt50 and Fe50Pt50–Cu, were constructed. An emphasis has been paid to the L10-FePt phase, which has a wide composition range with a solid solubility of Cu up to 40.0 at% at 600 °C. Its order-disorder transition temperature decreases rapidly when deviating from 54 at% Pt, but at different lower rates along (FePt)100-xCux and (Fe50-xCux)Pt50 with the increase of Cu. The ternary miscibility gap which originates from the Fe–Cu side has been studied by both experimental determinations and thermodynamic calculations. The results indicate that, at certain low temperatures, for instance 300 °C, the metastable miscibility gap can expand even up to 45 at% Pt, entering the L10-FePt phase region. An ordering transition mechanism of the L10-FePt phase stimulating by a two-phase separation was thus proposed. For a specially designed disordered Fe–Pt–Cu alloy, a metastable two-phase separation can take place firstly in the annealing process, driving the Cu atoms forming Cu-rich particles, leaving a large number of vacancies in the alloy, and consequently, accelerate the atomic diffusion and stimulate the subsequent L10 ordering transition. These results will provide a new perspective for the composition design of Fe–Pt–Cu catalysts and magnetic recording media.

Structural, spectroscopic (FTIR, FT-Raman and UV–Vis) investigations, Fukui function analysis and thermodynamic properties of diethyl 3,3′-(ethane-1,2-diylbis(azanediyl))(2Z,2′Z)-bis(but-2-enoate)

Diethyl 3,3′-(ethane-1,2-diylbis(azanediyl))(2Z,2′Z)-bis(but‑2-enoate) (DBE) molecule is characterized by infrared, Raman and UV–visible spectroscopic techniques. The structural parameters obtained using density functional theory (DFT) with B3LYP/6-311++G(d,p) level of theory closely match the experimental data. The molecule's characteristic functional groups were identified through vibrational spectra analysis. The IR and Raman spectra vibrational peaks were assigned based on Potential Energy Distribution (PED) analysis. Excitation wavelengths, oscillator strengths and excitation energies were determined through time dependent density functional theory (TD-DFT) calculations and compared to experimental data. Nonlinear optical (NLO) properties were calculated to predict the electric dipole moment and first-order hyperpolarizability of the molecule. The significant nonlinear optical properties values indicated that these materials possess excellent nonlinear optical properties, making them suitable for applications in telecommunication and signal processing. The Mulliken atomic charge, chemical activity analysis and Fukui functions were utilized to investigate the electron-poor, rich and reactive sites in conjunction with the optimized structures using the DFT method with B3LYP function and 6-311++G(d,p) basis set. Thermodynamic investigations have shown that key molecular parameters such as entropy, heat capacity and enthalpy increase as temperature rises.

Ciprofloxacin adsorption onto Pumice-bentonite composites: Modeling, kinetics, equilibriums and reusability studies

BackgroundA new Bentonite-loaded Pumice adsorbent (P-BNT3) was successfully synthesized as an efficient adsorbent for CIP removal from aqueous solutions. MethodsIn the present study, P-BNT3 composite synthesized by hydrothermal technique (24 h @160 °C) was loaded with Bentonite (BNT) using ultrasonication (20 min @25 °C) to remove CIP antibiotic. P-BNT3 composite was characterized by FTIR, XRD, BET, TGA, SEM, and TEM analyses. XRD, SEM, and TEM analyses indicate effective coupling of Pumice/ BNT strong layers with highly porous heterogeneous structure. Adsorption of CIP is studied as a function of pH, dosage, contact time, initial CIP concentration, and temperature in a batch reactor to obtain the maximum adsorption capacity (qm). Significant FindingsA MFSO kinetic model (R2= 0.983) and Langmuir and Dubinin–Radushkevich isotherm model (R2= 0.989 and 0.986) provide good fits to the experimental. The highest amount of CIP adsorbed is 54 mg/g at pH=2.0, which is 5 folds higher than pristine Pumice. The adsorption equilibrium was attained in 240 min with P-BNT3 for a CIP concentration of 30 mg/L. The characterization of spent composites after CIP adsorption suggested that CIP adsorption onto P-BNT3 composite is governed by π-π interaction, chemical complexation, and surface interactions. Based on thermodynamic investigation over the temperature range of 298 ̶ 318 K, CIP adsorption on P-BNT3 was a spontaneous (-ΔG°) and endothermic (ΔH°=+5.313) phenomenon. Furthermore, the adsorption-desorption procedure demonstrated that the composite could be efficiently reused up to 5 times. However, expensive desorption costs and the inevitable secondary effluent are a challenge in the practical implementation. Based on the findings, the P-BNT3 composite has great potential for the removal of other pharmaceutical compounds.

Decomposition of zinc ferrite-based solid waste by reductive leaching: Leaching kinetics and mechanism

Zinc ferrite-based solid waste is a vital zinc and iron secondary source in view of the numerous zinc ferrite will be ineluctably produced and enters into slags or residues during zinc smelting process. In this study, a reductive leaching process with zinc sulfide powder was employed to decompose zinc ferrite from solid waste. The leaching efficiency of zinc and iron can reach 90.27 % and 81.96 %, respectively, while the process went to the 90th min at 90 ℃ under the conditions: sulfuric acid concentration of 500 g/L, liquid-to-solid ratio of 20 mL g−1, mass ratio of silver flotation tailings to zinc sulfide of 5/1, silver flotation tailings particle size of + 180–250 μm, rotary speed of 400 rpm. Then, this leaching process confirmed to shrinking core model and was conducted by surface chemical reaction after kinetics and thermodynamics investigations. Ultimately, according to various tested data, the corresponding reaction mechanism was speculated as: Fe3+ was reduced to Fe2+ by zinc sulfide and hydrogen sulfide which was the product of zinc sulfide with H+, resulting in potential reduction and H+ activity elevation, accelerating zinc dissolution eventually. Meanwhile, almost all zinc sulfide and hydrogen sulfide were oxidized to monomorphic sulfur by Fe3+ where the utilization ratio of zinc sulfide was 97.28 %.

Effective adsorptive uptake of hexavalent chromium ions from aqueous systems utilizing a superior activated nanobentonite@cobalt ferrite@carboxymethylcellulose nanocomposite

Contamination of industrial and dietary water with Cr(VI) ions is known as a global concern. Industrial wastes containing elevated Cr(VI) concentration are hazardous and harmful to people and animals, if inappropriately treated. Consequently, in the current research, a novel nanocomposite of activated nanobentonite@cobalt ferrite@carboxymethylcellulose (ANB@CoFe2O4@CMC) is generated and characterized. Several characterization techniques were employed to confirm the structure of as-prepared ANB@CoFe2O4@CMC. The mean particle size range of this nanocomposite was found to be 22.5–26.2 nm. Through batch adsorption assessments, ANB@CoFe2O4@CMC was employed and optimized to remove Cr(VI) ions from aquatic medium providing optimum conditions of pH 2.0, 25–30 min shaking time, 25 mg nanocomposite dosage at 25 °C reaction temperature. Freundlich model was extremely relevant via linear and nonlinear expression. Thermodynamic investigations were investigated to conclude that both exothermal and spontaneous tendencies in governing Cr(VI) adsorptive uptake. The ANB@CoFe2O4@CMC was remarkably stable after five subsequent runs of regenerating and recycling. This investigation displayed the potential of ANB@CoFe2O4@CMC as a powerful nanocomposite material for Cr(VI) recovery from diverse waters via a microcolum technique, exhibiting uptake values up to 87.9–95.8 %. As a result, the evaluated ANB@CoFe2O4@CMC could be successfully illustrated a superior material for effective multi-uptake Cr(VI) ions from water.