Values Of ΔG Research Articles

An efficient and universal In silico screening strategy for acquisition of high-affinity Aptamer and its application in analytical utility

Numerous aptamers against various targets have been identified through the technology of systematic evolution of ligands by exponential enrichment (SELEX), but the affinity of these aptamers are often insufficient due to the limitations of SELEX. Therefore, a more rational in silico screening strategy (ISS) was developed for efficient screening of high affinity aptamers, which took shape complementarity and thermodynamic stability into consideration. Neuron specific enolase (NSE), a tumor marker, was selected as the target molecule. In the screening process, three aptamer candidates with good shape complementarity, lower ΔG values, and higher ZDOCK scores were produced. The dissociation constant (Kd) of these candidates to NSE was determined to be 10.13 nM, 14.82 nM, and 2.76 nM, respectively. Each of them exhibited higher affinity to NSE than the parent aptamer (Kd = 23.83 nM). Finally, an antibody-free fluorescence aptasensor assay, based on the aptamer with the highest affinity, P–5C8G, was conducted, resulting in a limit of detection (LOD) value of 1.8 nM, which was much lower than the parental aptamer (P, LOD = 12.6 nM). The proposed ISS approach provided an efficient and universal strategy to improve the aptamer to have a high affinity and good analytical utility.

Cytotoxic Activities, Determining Toxin, and Molecular Docking of Ovary Pufferfish (Tetraodon leiurus) in Singkarak Lake as Cancer Chemoprevention Candidate

The primary toxin class discovered in freshwater pufferfish is a category of neurotoxins called PSTs (Paralytic shellfish toxins) and pufferfish toxin has been observed to have biological, biochemical, and cytotoxic effects on cancer cell lines. Therefore, it is crucial to determine the cytotoxic activity, toxins present in the ovary of T. leiurus, and interaction between ligand (toxin compound) and receptors test. This study used the MTT method in the T47D cell lines, liquid chromatograph-tandem mass spectrometry (LC-MS/MS), and analysis of the molecular interaction using molecular docking. The ovary of T. leiurus had cytotoxicity on the T47D cell, having an IC50 value of 229.535 μg/ml, and generated a chromatogram with a retention duration of 1.25 min that was similar to the Decarbamoylneosaxitoxin (dcNEO) standard solution. In molecular interactions between the dcNEO ligand to receptors, the lowest ΔG value was -9.29 kcal/mol at the Nav 1.7 receptor, and the lowest KI value was 1.23 µM at the Mcl-1 receptor. These findings indicate that the ovary of T. leiurus is cytotoxic to the T47D cell line and contains dcNEO toxin. It is more stable for the dcNEO ligand to engage with the Nav 1.7 receptor than with other receptors, and it inhibits the Mcl-1 receptor more potently than with other receptors. These findings indicate that the ovary of T. leiurus may be chemotherapy for the prevention of cancer strategy.

Removal of Methylene Blue by adsorption onto natural and purified clays: Kinetic and thermodynamic study

The present work explores the optimization of experimental conditions for the adsorption of the organic cationic dye methylene blue (MB) by natural and purified clays. The adsorption capacities of samples were determinate to evaluate the efficiency of the purification process. At first, we performed mineralogical and textural analysis of the clay minerals, namely, smooth clay (SC), rigorous clay (RC) and bentonite clay (BC), using various techniques, particularly, X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and X-ray fluorescence (XRF). The characterizations data showed that SC and RC are mainly composed of smectite associated with kaolinite, illite and chlorite. While BC is considered a mesoporous and swelling clay with smectite as the major component. The cation exchange capacity (CEC) was determinate as a 6.30 meq/100 g, 10.69 meq/100 g and 32.64 meq/100 g for SC, RC and RC natural samples respectively. It was noticed that the CEC as well as the specific surface area increase once the impurities associated with the clay are removed. A preliminary study was carried out to elucidate the influence of different parameters; such as contact time, exchangeable cation, solute concentration, temperature and pH on MB adsorption in aqueous solution by clays. The adsorption equilibrium data were analyzed by the linear and nonlinear forms of the Langmuir and Freundlich isotherm models. The Langmuir isotherm fitted well with the experimental data, and the pseudo-second-order kinetic model represented appropriately the adsorption kinetics of MB dye. Moreover, purified clays showed improved adsorption capacity for MB compared to pristine ones: 147.64; 257.69 and 1383 mg/g versus 128.75; 193.4 and 681.85 mg/g for SC, RC and BC respectively. This is attributed to a suitable specific surface, ion exchange capacity and electrostatic interactions as result of a more adequate texture and composition of our treated clays. The thermodynamic studies reveled negative Gibbs free energy change (ΔG) values (from -6.293 to -18.608 KJ.mol−1), positive enthalpy change (ΔH) values, exceeding 40 kJ/mol and positive entropy change (ΔS) values confirming the spontaneous, endothermic and chemisorption nature of the MB adsorption process. The results show that the tested purified clays are efficient in MB removal and can be used as an alternative to the commercial adsorbents, which are often relatively expensive.

Extraction of Cerium from Nitric Acid Medium using Cyanex 302 and Cyanex 572

In this paper, the extraction of cerium from the synthetic environment ([Ce]=0.04 M) was investigated using the solvent extraction method with a mixture of solvents. Considering that the synergy of extractants can lead to the improvement of cerium extraction, Cyanex 302 solvent was used for synergy with Cyanex 572. The results showed that the combination of Cyanex 572-Cyanex 302 can extract a high percentage of cerium (> 90%). Also, the value of ΔG is equal to 18.61 (kJ/mol), so the extraction reaction of Ce (III) is non-spontaneous.

Effect of anaerobic digestion pretreatment on pyrolysis of distillers’ grain: Product distribution, kinetics and thermodynamics analysis

To systematically examine the effects of anaerobic digestion (AD) pretreatment on product distribution and kinetics of distillers’ grains (DG) and its digestates collected at different AD durations, Py-GC/MS and TG analyses were conducted. Py-GC/MS analysis revealed a reduction in the proportion of oxygenated and nitrogenous compounds in all digestates and increase the share of hydrocarbons: 46.72% (SD-2), 65.53% (SD-4), 43.20% (SD-6) and 50.05% (SD-8) than DG (38.61%). To assess activation energy, Friedman, Kissinger-Akahira-Sunose and Flynn-Wall-Ozawa models were employed with average values ranging from 159.54 to 170.96 kJ mol−1 for DG, 156.59–165.42 kJ mol−1 for SD-2, 15.67–166.47 kJ mol−1 for SD-4, 153.28-159-45 kJ mol−1 for SD-6, and 156.02–167.37 kJ mol−1 for SD-8, which were lowered than DG. Thermodynamic studies showed positive ΔH and ΔG values, suggesting that the pyrolysis of DG and digestates is non-spontaneous. The negative ΔS values implied that the degree of disorder in products resulting from bond dissociation was lower than initial reactants. These findings provide valuable insight into the potential of AD as a pretreatment method and offer an understanding of the pyrolysis behavior of digestates. This study not only offers practical guidance but also contributes to the theoretical framework for utilizing AD as a pretreatment method for pyrolysis.

New Perspective on the Interaction Behavior Between Riboflavin and β Lactoglobulin-β Casein Complex by Biophysical Techniques.

Riboflavin (RF) is a vitamin that only exists in plants and microorganisms and must be procured externally by humans. On the other hand, there are two major allergic factors in cow's milk, including β-lactoglobulin (βLG) and β-casein (βCN), while their allergic properties can be eliminated by binding to micronutrients. In this regard, we examined the binding process of RF to βLG and βCN in the binary and ternary systems by different spectroscopies such as zeta potential, electric conductivity, and molecular modeling. According to the result of the fluorescence spectrum regarding the interaction of RF with βLG and βCN in binary and ternary systems, an increase in RF concentration declined the fluorescence intensity of three systems and also caused the quenching of proteins. Static quenching plays a pivotal role in the formation of stable interactions. The obtained thermodynamic parameters by Van't Hoff equation ascertained the predominance of hydrogen bonds and van der Waals interaction in all the systems. Considering how the negative value of ΔH0 resulted in the negative value of ΔG0, the systems were assumed to be enthalpy driven. The outcomes of circular dichroism (CD) disclosed that the attachment of RF to the targets of systems increased their a-helix content, which particularly included the binding of RF to βLG that led to the conversion of β-sheet to α-helix content. As indicated by the results of zeta potential, the low concentration of RF contained the dominance of hydrophobic forces in the interactions, whereas the enlargement of this concentration prevailed electrostatic forces. Moreover, conductometry measurements showed an extension in the rate of ionizable groups due to the addition of RF to the systems, which may increase the probability of an interaction between RF, βCN, and βLG in binary and ternary systems. In consistency with the outcomes of molecular dynamics simulation, the data of molecular docking approved the capability of RF in forming strong and stable interactions with βCN and βLG.

DFT study of bismuth subsalicylate adsorption on bow-tie dendrimer nanocarrier as drug delivery agents

Ulcerative colitis is a subtype of inflammatory bowel disease with symptoms that progress from mild to severe. It has multiple treatment options, but requires effective monotherapy for its treatment. In this context, a theoretical study was conducted on the interaction of bismuth subsalicylate (BSS) with a bow-tie (DP) polyester dendrimer for use as a nanocarrier. The reactivity indices and frontier molecular orbitals indicate that these systems can interact. The complexes were formed through the interaction of the oxygens of the dendrimer with the bismuth of the BSS and also by hydrogen bonding. The ΔG values were > 0 kcal mol−1, which indicated that the systems are not spontaneous, although the values of adsorption energies (Eads) and enthalpy showed values < 0 kcal mol−1, showing that interactions can occur. Topological analyses based on the quantum theory of atoms in molecules allowed the characterization of molecular interactions. The interactions of Bi with O were partially covalent, and the hydrogen bonds (O…H) were classified as weak or moderate. Finally, the interactions between the nanocarrier and the drug had positive results, which can be attributed to the polyester dendrimer being a good nanocarrier for the release of BSS.

Interaction analysis of a new NHC precursor and its Ag-NHC complex with bovine serum albumin by spectrophotometric and molecular docking methods

Potential bioactive molecules must reach the target tissue safely and serum albumin, which is a well-known major component in human blood, is an efficient transporter. Therefore, the interactions of possible bioactive species with serum albumin must be determined. In the current study, an N-heterocyclic carbene precursor and its silver complex were synthesized, characterized, and analyzed for interactions with bovine serum albumin. Stern-Volmer constant was recorded as 4.50 × 105 for Ag-NHC with a 1.255 binding number at 298 K. Also, the molecules have spontaneously interacted with bovine serum albumin with a negative ΔG value (−32.93 kJ mol−1) for the complex at 298 K. Additionally, the effects of Ca2+, Mg2+, and Zn2+ on binding properties were evaluated by fluorescence spectroscopy. The binding constant of the complex was recorded as 6.76 × 103 in the presence of Zn2+ and 5.93 × 105 without the metals. The molecules were optimized by DFT-based calculations and the details of the bindings were investigated by molecular docking methods. Ag-NHC has interacted with the IIA subdomain region of bovine serum albumin with −8.46 kcal/mol.

Removal of 17α-ethinylestradiol (EE2) from aqueous solutions by peanut shells (Arachis hypogaea): adsorption kinetic, isothermal, and thermodynamic studies

Abstract This study evaluated the potential of using raw peanut shells as an adsorbent to remove the hormone 17α-ethylestradiol (EE2) from water. High-performance liquid chromatography with fluorescence detection was used in the determination of EE2. Kinetics data were tested with the pseudo-first-order, pseudo-second-order, and Elovich models, whereas isothermal data were tested with the Langmuir, Freundlich, and Sips models, and the parameters (ΔG°, ΔH° and ΔS°) were evaluated. A maximum removal rate of approximately 90% was observed in a solution with an initial EE2 concentration of 263.2 μg L−1, under the best experimental conditions (stirring speed = 500 rpm, pH = 6, and adsorbent mass = 2 g in 24 h), and showed an adsorption capacity of 17.3 μg g−1 at 306 K. The pseudo-first-order model adjusted better to the data in the studied temperature range, presenting a potential barrier of 16.69 kJ mol−1 (Ea) for adsorption kinetics. The Freundlich model and Sips model adjusted better to the data in the studied temperature range. The negative value of ΔG° (−15.87 kJ mol−1 at 306 K) confirmed the viability and spontaneity of the adsorption process. The positive value of ΔH° (168.9 kJ mol−1) characterized the chemical nature of the adsorption process.

Use of Sr2Mg(BO3)2 in Congo red removal from aqueous solutions: Synthesis, adsorption, isotherm, kinetic study

Sr2Mg(BO3)2 was prepared by a solution combustion method at 900 °C for 6 hour in air. The prepared adsorbent was characterized by X-Ray Diffraction (XRD). The XRD pattern of Sr2Mg(BO3)2 is in agreement with the ICDD File No: 01-076-9795. The particle morphology of the adsorbent was investigated by scanning electron microscope (SEM). The average size of particles is about 3–10 µm. The Congo red dye was removed from aqueous solution using Sr2Mg(BO3)2. The effect of time, initial concentration, pH, temperature and dosage on adsorption were investigated. The Freundlich model fitted according to equilibrium data and maximum adsorption capacity is 886.952 mg/g. According to theories of pseudo-second-order kinetics, the removal procedure involves chemical adsorption. According to the thermodynamic data, negative ΔG values indicated that adsorption of Sr2Mg(BO3)2 occurred spontaneously and negative ΔH values, the adsorption process was exothermic. Sr2Mg(BO3)2 is a useable material for Congo red dye removal.

Loading of Silver (I) Ion in L-Cysteine-Functionalized Silica Gel Material for Aquatic Purification.

The L-cysteine-functionalized silica (SG-Cys-Na+) matrix was effectively loaded with silver (I) ions using the batch sorption technique. Optimal Ag(I) loading into SG-Cys-Na+ reached 98% at pHi = 6, 80 rpm, 1 mg L-1, and a temperature of 55 °C. The Langmuir isotherm was found to be suitable for Ag(I) binding onto SG-Cys-Na+ active sites, forming a homogeneous monolayer (R2 = 0.999), as confirmed by FTIR spectroscopy. XRD analysis indicated matrix stability and the absence of Ag2O and Ag(0) phases, observed from diffraction peaks. The pseudo-second-order model (R2 > 0.999) suggested chemisorption-controlled adsorption, involving chemical bonding between silver ions and SG-Cys-Na+ surface. Thermodynamic parameters were calculated, indicating higher initial concentrations leading to increased equilibrium constants, negative ΔG values, positive ΔS values, and negative ΔH. This study aimed to explore silver ion saturation on silica surfaces and the underlying association mechanisms. The capability to capture and load silver (I) ions onto functionalized silica gel materials holds promise for environmental and water purification applications.

Thermodynamic Insights into Sustainable Aviation Fuel Synthesis via CO/CO2 Hydrogenation

The transformation of CO/CO2 hydrogenation into high-density sustainable aviation fuel (SAF) represents a promising pathway for carbon emission reduction in the aviation industry but also serves as a method for renewable energy assimilation. However, current hydrocarbon products synthesized through CO/CO2 often focus on various catalytic paths with high selectivity and high conversion rates rather than the synthesis of SAFs with complex components. This study undertakes a thermodynamic investigation into the direct or indirect synthesis of SAFs from CO/CO2 hydrogenation. By analyzing the synthesis of seven aviation fuels defined by the American Society for Testing and Materials (ASTM) D7566 standard, our study reveals a temperature-dependent reduction in the reaction driving force for all products. Specifically, for CO, ΔG transitions from approximately −88.6 J/(mol·K) at 50 °C to 26.7 J/(mol·K) at 500 °C, with the switch from negative to positive values occurring around 390 °C. Similarly, for CO2, ΔG values change from approximately −66.7 J/(mol·K) at 50 °C to 37.3 J/(mol·K) at 500 °C, with the transition point around 330 °C. The thermodynamic favorability for various hydrocarbon products synthesized is also examined, highlighting a transition at temperatures of around 250 °C, beyond which the thermodynamic drive for the synthesis of aromatic compounds increasingly surpasses that of cycloparaffin synthesis. Our findings also underscore that the products with a higher aromatic content yield a lower H2/CO2 ratio, thus reducing hydrogen consumption. The influence of cycloparaffin and aromatic proportions in the typical SAF products on the ΔG is also explored, revealing that an increase in cycloparaffin content in SAFs slightly elevates the ΔG, whereas an increase in aromatic content significantly reduces ΔG, thereby markedly enhancing the thermodynamic drive of the CO/CO2 hydrogenation reaction. These findings underscore the thermodynamic preference for synthesizing SAF with a higher proportion of aromatic compounds, shedding light on potential pathways for optimizing fuel synthesis to improve efficiency. Finally, the thermodynamic challenges and potential solutions involved in synthesizing SAFs via specific intermediate compounds are discussed, presenting opportunities for more strategic process schemes in industrial scenarios.

Thermo-kinetic behaviour of green synthesized nanomaterial enhanced organic phase change material: Model fitting approach

Metal, carbon and conducting polymer nanoparticles are blended with organic phase change materials (PCMs) to enhance the thermal conductivity, heat storage ability, thermal stability and optical property. However, the existing nanoparticle are expensive and need to be handle with high caution during operation as well during disposal owing to its toxicity. Subsequently handling of solid waste and the disposal of organic PCM after longevity usage are of utmost concern and are less exposed. Henceforth, the current research presents a new dimension of exploration by green synthesized nanoparticles from a thorny shrub of an invasive weed named Prosopis Juliflora (PJ) which is a agro based solid waste. Subsequently, the research is indented to decide the concentration of green synthesized nanoparticle for effective heat transfer rate of organic PCM (Tm = 35–40 °C & Hm = 145 J/g). Furthermore, an in-depth understanding on the kinetic and thermodynamic profile of degradation mechanism involved in disposal of PCM after usage via Coats and Redfern technique is exhibited. Engaging a two-step method, we fuse the green synthesized nanomaterial with PCM to obtain nanocomposite PCM. On experimental evaluation, thermal conductivity of the developed nanocomposite (PCM + PJ) increases by 63.8% (0.282 W/m⋅K to 0.462 W/m⋅K) with 0.8 wt% green synthesized nanomaterial owing to the uniform distribution of nanoparticle within PCM matrix thereby contributing to bridging thermal networks. Subsequently, PCM and PCM + PJ nanocomposites are tested using thermogravimetric analyzer at different heating rates (05 °C/min; 10 °C/min; 15 °C/min & 20 °C/min) to analyze the decomposition kinetic reaction. The kinetic and thermodynamic profile of degradation mechanism involved in disposal of PCM and its nanocomposite of PCM + PJ provides insight on thermal parameters to be considered on large scale operation and to understand the complex nature of the chemical reactions. Adopting thirteen different chemical mechanism model under Coats and Redfern method we determine the reaction mechanism; kinetic parameter like activation energy (Ea) & pre-exponential factor (A) and thermodynamic parameter like change in enthalpy (ΔH), change in Gibbs free energy (ΔG) and change in entropy (ΔS). Dispersion of PJ nanomaterial with PCM reduces Ea from 370.82 kJ/mol−1 to 342.54 kJ/mol−1 (7.7% reduction), as the developed nanomaterial is enriched in carbon element and exhibits a catalytic effect for breakdown reaction. Corresponding, value of ΔG for PCM and PCM + PJ sample within heating rates of 05–20 °C/min varies between 168.95 and 41.611 kJ/mol−1. The current research will unbolt new works with focus on exploring the pyrolysis behaviour of phase change materials and its nanocomposite used for energy storage applications. This work also provides insights on the disposal of PCM which is an organic solid waste. The thermo-kinetic profile will help to investigate and predict the optimum heating rate and temperature range for conversion of micro-scale pyrolysis to commercial scale process.

Improvement of the cardiovascular effect of methyldopa by complexation with Zn(II): Synthesis, characterization and mechanism of action

Backgroundthe antihypertensive drug α-methyldopa (MD) stands as one of the extensively used medications for managing hypertension during pregnancy. Zinc deprivation has been associated with many diseases. In this context, the synthesis of a Zn coordination complex [Zn(MD)(OH)(H2O)2]·H2O (ZnMD) provide a promising alternative pathway to improve the biological properties of MD. MethodsZnMD was synthesized and physicochemically characterized. Fluorescence spectral studies were conducted to examine the binding of both, the ligand and the metal with bovine serum albumin (BSA). MD, ZnMD, and ZnCl2 were administered to spontaneous hypertensive rats (SHR) rats during 8 weeks and blood pressure and echocardiographic parameters were determined. Ex vivo assays were conducted to evaluate levels of reactive oxygen species (ROS), thiobarbituric acid reactive substances (TBARS), and nitric oxide (NO). Cross-sectional area (CSA) and collagen levels of left ventricular cardiomyocytes were also assessed. Furthermore, the expression of NAD(P)H oxidase subunits (gp91phox and p47phox) and Superoxide Dismutase 1 (SOD1) was quantified through western blot analysis. ResultsThe complex exhibited a moderate affinity for binding with BSA showing a spontaneous interaction (indicated by negative ΔG values) and moderate affinity (determined by affinity constant values). The binding process involved the formation of Van der Waals forces and hydrogen bonds. Upon treatment with MD and ZnMD, a reduction in the systolic blood pressure in SHR was observed, being ZnMD more effective than MD (122 ± 8.1 mmHg and 145 ± 5.6 mmHg, at 8th week of treatment, respectively). The ZnMD treatment prevented myocardial hypertrophy, improved the heart function and reduced the cardiac fibrosis, as evidenced by parameters such as left ventricular mass, fractional shortening, and histological studies. In contrast, MD did not show noticeable differences in these parameters. ZnMD regulates negatively the oxidative damage by reducing levels of ROS and lipid peroxidation, as well as the cardiac NAD(P)H oxidase, and increasing SOD1 expression, while MD did not show significant effect. Moreover, cardiac nitric oxide levels were greater in the ZnMD therapy compared to MD treatment. ConclusionBoth MD and ZnMD have the potential to be transported by albumin. Our findings provide important evidence suggesting that this complex could be a potential therapeutic drug for the treatment of hypertension and cardiac hypertrophy and dysfunction.

Intensifying of phenol removal from aqueous solutions using ACTF as a hybrid carbon nanostructure: Isotherms, kinetics and thermodynamics study

Activated carbon thin film (ACTF) was prepared via a single-step mixing method through thermal fabrication that was utilized for the removal of phenol in the batch aqueous media. The prepared adsorbent was characterized using TEM, XRD, FTIR, BET, EDX, Raman, and TGA analyses. Batch adsorption experiments were studied by using the effects of different parameters such as pH, temperature, dose, contact time, and initial concentration of phenol solution on adsorption. The maximum phenol removal by ACTF was approximately 89.5% at pH 4, adsorbent dose of 1 g/L, and 50 ppm for the initial concentration of phenol at room temperature through 150 min. Adsorption data were modeled using four adsorption isotherm models (Langmuir, Freundlich, Temkin, and D-R) and three kinetic models (pseudo first order, pseudo second order, and Intraparticle diffusion) using linear and non-linear regression methods. The chi-square (X 2) and the correlation coefficient (R 2) were both used as error analysis techniques to find the best-fitting equations. The results showed that phenol adsorption on ACTF adsorbent fitted more accurately with nonlinear regression models, which is consistent with Freundlich isotherm and pseudo-second order form. Also, thermodynamic results demonstrated that attachment of phenol onto ACTF adsorbent was spontaneous (negative value of ΔG) and exothermic (negative value of ΔH) with decreasing temperature from 55 °C to 25 °C. Synthesized ACTF showed good regeneration capacity with 0.1 M NaOH as the eluent, making it an appropriate adsorbent for the elimination of phenol. This study evidenced the efficacy of ACTF as a phenol adsorbent.

Goat manure waste and palm oil mill effluent, viable crude oil degradation substrates: A thermodynamic and composting investigation studies

The composting and thermodynamic processes of crude oil (CO) degradation using the compost of goat manure origin (CGMO) and compost of palm oil mill effluent origin (CPOMEO) were studied. Microbial activity was investigated using the carbon dioxide (CO₂) evolution test. The physiochemical properties of the composts and that of the treated CO-contaminated soil (COCS) were also investigated. In particular, CGMO significantly improve CO degradation with the highest CO₂ evolution rate of 45 mg/g compared to the CPOMEO and the control. The CO degradation rates of 85.7 %, 71.4 %, and 14 % corresponded to the first-order CO degradation rate constants of 0.743 day−1, 0.689 day−1, and 0.136 day−1 for CGMO, CPOMEO, and control, respectively. The Fourier transforms infrared (FTIR) spectral pattern for both composts revealed adsorption bands that were identifiable with polysaccharides, potassium, and nitrogen, whereas the scanning electron microscope and energy dispersive spectrophotometry (SEMEDX) of CPOMEO indicated carbon and oxygen as the sole compositions. The negative ΔG and ΔH values indicated the spontaneity and exothermic nature of the CO composting process, respectively.

Photocatalytic evaluation of synthesized MnO2/Fe3O4 NCs by Q. infectoria extract for removal Ni(II) and phenol: Study phytochemical, kinetics, thermodynamics, and antibioactivity

In the present study, the plant extract of the Quercus infectoria galls was used as a reducing, capping, and stabilizer agent for green synthesized MnO2 nanoparticles (NPs) and MnO2/Fe3O4 nanocomposites (NCs) due to its reduction ability from polyphenol and antioxidant content. The green synthesized nanomaterials have been characterized by various techniques such as FTIR, UV–vis, XRD, SEM, EDS, and TEM. The average size of about 7.4 and 6.88 nm was estimated for the NCs crystals of SEM images and XRD analysis by the Scherrer and Williamson-Hall methods. The green synthesized MnO2/Fe3O4 NCs (dosage: 0.1 g) have shown high photocatalytic activity for the removal of Ni(II) in acidic and basic solutions under visible irradiation (220 V lamp). The removal efficiency for the Ni(II) solution (3.6 × 10−3 M) at pH = 3 was increased to pH = 12 from 56 % to 98 %. The oxidase-like activity of MnO2/Fe3O4 NCs at different dosages (0.05, 0.1, and 0.15 g) for the removal and colorimetric of phenol (1 g/40 mL) in the presence 4-AAp (1 g) was seen after only 28, 13, and 5 s, respectively. The kinetic evaluation results showed the pseudo-second-order kinetics model closely matched the adsorption capacity theoretical values qe,cal (578.03, 854.70, 892.85, and 917.43 mg.g−1) and experimental values qe,exp (521.84, 839.74, 887.86, and 913.22 mg.g−1) at different initial pH solution (3−12) for Ni(II) removal. In addition, the investigation of isotherm models revealed that the Langmuir model (R2 = 0.9955) explains a better estimate for a monolayer and favorable removal of Ni(II) ions onto NCs. Also, the low Temkin constant, BT < 0 (0.0200 kJ.mol−1), and positive ∆H° value (0.103 kJ.mol−1.K−1) illustrated that Ni(II) removal is physical sorption and endothermic process. However, the obtained thermodynamic results showed the negative values ΔG° with the increase in temperature (303–318 K) toward a spontaneous removal process of Ni(II). Finally, the plant antioxidant (200 to 3200 μg/mL) and antimicrobial activities (0.001 to 0.1 g/mL) for plant extract, MnO2 NPs, and MnO2/Fe3O4 NCs were evaluated against Gram-positive and Gram-negative bacteria species.

Determination of Thermodynamic Parameters of Phenol Adsorption onto Sewage Sludge based Adsorbent by different Methods

The aim of this study is the determination of thermodynamic parameters of the adsorption of phenol onto sewage sludge based adsorbent (SSBA) by different methods. Thermodynamic parameters are calculated from three equilibrium constants (Kc) that were derived from the isotherm constants of Langmuir (KL), the distribution coefficient (Kd) and Freundlich isotherm exponent (n). For this, removal of phenol from aqueous solutions by adsorption under batch equilibrium experimental conditions at 293, 303 and 328 K was investigated. All values obtained for ΔG° are negatives this indicated that the adsorption process of phenol on the SSBA is spontaneous and thermodynamically feasible process. We also note that as the temperature increases, the absolute value of ΔG° decreases, it shows that the adsorption is more spontaneous at low temperatures. All values of the standard enthalpy ΔH° are negative and less than 35 kJ.mol-1 which confirm that the process is an exothermic physisorption. The negative values of the standard entropy ΔS° clearly show that the arrangement of phenol molecules is more preferred on the surface of the adsorbent.

Edible waste oil to biofuel using reclaimable g-C3N4/HAp/Fe3O4/K2CO3 nanobiocomposite catalyst: Toxicity evaluation and optimization

In the current work, the new heterogeneous nonobiocomposite of g-C3N4/HAp/Fe3O4/K2CO3 was made from chicken bone and melamine and used in biofuel generation from edible waste oil (EWO). FTIR, SEM, Map-EDX, BET, VSM, and XRD techniques confirmed that the catalyst was synthesized. The magnetic saturation number and the BET value of g-C3N4/HAp/Fe3O4/K2CO3 were determined to be 8.89 emu.g−1 and 3.95 m2.g−1, respectively. The impact of temperature, time, catalyst mass, and the ratio of methanol: Oil (MeOH: Oil) on biofuel production was explored using response surface method-central composite design. The maximum yield of biofuel from EWO (98.52 %) achieved at contact time of 150 min, temperature of 65 °C, catalyst amount of 3 wt%, and MeOH: Oil ratio of 15:1. Activation energy and k0 for the transesterification process were computed to be 58.91 kJ.mol−1 and 3.24 × 107 min−1, respectively. The values of ΔH and ΔG were determined positive for the biofuel production process, which indicates that the biofuel production process is exothermic and non-spontaneous. The value of the environmental factor (E) also showed that biofuel production has negligible harmful effects on the environment. The heterogeneous catalyst can be effectively reused many times in the transesterification process. The produced biofuel was in good compliance with famous standards and can serve as a suitable fuel source.

Qualitative and Quantitative Investigation of Biochar-Cu0 Composite for Nickel Adsorption.

The current investigation deals with the treatment of water pollution that is caused by the leaching of nickel ions from the metallurgical industry and new-energy batteries. Therefore, an eco-friendly treatment of nickel through the use of a composite of cotton stalk biochar with nanozerovalent copper has been presented in this investigation signifying the impact of zerovalent copper in enhancing the adsorption capacity of biochar for nickel adsorption. Thermogravimetric analysis data showed the adsorbent to be significantly stable in the higher thermal range, whereas transmission electron microscopy analysis confirmed the particles to be 27 nm and also showed the cubic geometry of the particles. A much closer scanning electron microscopy analysis shows the morphology of particles to be cubic in shape. Batch adsorption indicated a positive influence of pH increase on adsorption due to the electrostatic attraction between positive nickel ions and post point of zero charge (pHPZC) negative surface of copper biochar composite (pH > 5.5). A high adsorption rate was observed in the first 60 min, whereas adsorption increased with the increase in temperature from 303 to 318 K. Kinetic modeling confirmed the pseudo-first-order to fit best to the data. The apparent activation energy (11.96 kJ mol-1) is indicative of the chemical nature of the process. The adsorption data fitted well to the Langmuir adsorption model. The negative values of apparent ΔG° and the positive values of apparent ΔH° indicate the spontaneity and endothermicity of the process, respectively, whereas the positive values of apparent ΔS° point toward increased randomness during the process. Postadsorption XPS suggests the adsorption of nickel on the surface of biochar composites in the form of Ni(OH)2 and NiO(OH).