Values Of ΔG Research Articles

The crucial role of different NaOH activation pathways on the algae-derived biochar toward carbamazepine adsorption

In this study, algae present in wastewater were utilized as precursors for synthesizing a range of biochar (BC) samples to serve as efficient adsorbents for the removal of carbamazepine (CBZ). The impact of modification on BC, activated through the NaOH impregnation method (IBC), and the NaOH dry mixing-pyrolysis (DBC) method, was systematically explored. It was observed that only the surface of IBC became rough due to NaOH impregnation activation, while the DBC structure exhibited additional fine pores within its interior. Furthermore, after NaOH activation, a significant number of oxygen-containing functional groups were introduced onto the surface of the prepared BC samples, with the proportion of O species differing between the two NaOH activation methods. Based on the results from adsorption experiments and kinetic model simulation, CBZ adsorption by BC samples followed a monolayer homogeneous adsorption reaction with excellent pH tolerance, where H-bond (CO⋯H–N) was identified as the primary driving force. From an adsorption thermodynamics perspective, it is hypothesized that the high proportion of CO causes the ΔG value to shift from positive to negative, indicating that CBZ adsorption by DBC is a spontaneous reaction. Under optimal conditions, the DBC samples demonstrated an exceptional adsorption capacity, reaching 118.4 mg/g, with the removal rate of CBZ exceeding 99 %. This study offers theoretical insights into the preparation, modification, and adsorption mechanisms of BC-based adsorbents.

Enhanced adsorption performance of tetracycline in aqueous solutions using Mg-Al-LDH/AC nanocomposite

Water contamination with antibiotics promotes environmental antibiotic resistance. Tetracycline(TC), commonly used in agriculture, pollutes water and enables bacteria to develop resistance genes. Mg-Al-layered double hydroxides/Activated carbon (Mg-Al-LDH/AC) nanocomposite effectively removes tetracycline from water in this study. The synthesized adsorbent was characterized using Brunauer–Emmett–Teller (BET), Fourier-transform Infrared Spectroscopy (FT-IR), Field Emission Scanning Electron Microscopy (FESEM), X-Ray Diffraction (XRD), and Energy-dispersive X-ray spectroscopy (EDS) tests, and exhibited a large surface area of 105.46 m2/g, a total pore volume of 0.4571 cm3/g, and an average pore diameter of 27.99 nm. The optimal conditions for eliminating TC using the Mg-Al-LDH/AC nanocomposite were determined via the central composite design response surface methodology (CCD-RSM) approach. The responses were evaluated using a second-order polynomial multiple regression model, which was found to be a satisfactory fit to the data based on the analysis of variance (R2 = 0.9690, R2Adj = 0.9478, and R2Pred = 0.9042). The ideal conditions were identified as pH = 5.1, 0.11 g of adsorbent, a TC concentration of 50 mg/L, and a contact time of 90 min. The adsorption isotherms showed that TC elimination follows the Langmuir model with a maximum adsorption capacity of 106.4 mg/g and a high R2 value of 0.9986. The kinetics of the TC adsorption process was found to fit the pseudo-second-order model with a correlation value of 0.9997. The values of ΔG, ΔH, and ΔS for TC were determined to be 1.90 kJ/mol (at 333.15 K), −41.97 kJ/mol, and −0.131 kJ/(mol·K), respectively. Additionally, the study showed that ionic strength did not affect the effectiveness of TC removal, and the adsorbent was effective in removing TC antibiotics in a range of ionic strengths. Finally, the study found that adding 20% by weight of AC to LDH resulted in the best TC removal efficiency.

Spectrophotometric investigation on interactions of dye with surfactant in aqueous as well as alcoholic media

The interaction of the methyl orange (MO) dye with cetyltrimethylammonium bromide (CTAB) in propanol, butanol, and water was studied using spectrophotometry method. The NLREG approach was used to compute the distribution constant which is the lower as carbon number increases which resembles that value of distribution constant 0.07161476, 0.00060913, 0.00010865 is of water, 1-propanol, 1-butanol media respectively. The Benesi-Hilderbrand and Hashemi and Sun equations were also used to determine the binding constant (Kb) and Gibbs free energy of binding (ΔG°). As the alkyl chain lengthened, the ΔG° value shifted more negatively in comparison to water. The spontaneous nature of CTAB binding with MO was suggested by the negative value of ΔG°. As the concentration of CTAB in the water & alcoholic media increased, the MO absorption dramatically blue-shifted from 464 nm (water) to 440–450 nm (propanol, butanol). These findings showed that the alkyl chain plays a role in reducing absorbance. The MO absorbance in the water, 1-propanol or 1-butanol media decreased with increasing CTAB concentration (hyperchromic shift).

Raw sawdust utilization for the removal of acid red57 and basic fuchsin dyes from aqueous solution: equilibrium, kinetics, and thermodynamic investigation

The aim of work is the use of a cheap adsorbent; sawdust (SD), for the adsorption of anionic dye, acid red57 (AR57), and cationic dye, basic fuchsin (BF). The adsorption of AR57 and BF on SD increased by increasing contact time and adsorbent dosage, while decreased with the increase of temperature and initial dye concentration. The increase in pH decreased the adsorption of AR57 and increased the adsorption of BF. The effective pH, adsorbent dose, and contact time on the AR57 removal efficiency were found to be 3, 0.1 g and 50 min, respectively. While for BF it was found to be 6, 0.2 g and 50 min, respectively. Fitting equilibrium data to Langmuir, Freundlich and Temkin isotherms showed that Freundlich model is the most suitable to describe the acid red57 and basic fuchsin. The kinetic studies indicate that the adsorption of AR57 and BF follows a pseudo-second-order model. The adsorption of both AR57 and BF is spontaneous (ΔG = −3.97, −3.27 kJ/mol) and exothermic (ΔH = −22.9, −8.3 kJ/mol) with negative values of ΔG and ΔH. The negative values of ΔS of both AR57 and BF (ΔS = −64.6, −16.7 J/mol. K) showed that the randomness decreases through the adsorption process.

Novel Method for the Arsenic Removal Experiment and Mechanism Analysis.

This study focuses on the hydrothermal synthesis of magnetically activated carbon and its efficacy in As(III) adsorption. The successful incorporation of magnetite nanoparticles within the porous carbon structure was confirmed, enriching the adsorbent's properties. Comprehensive characterization was performed to analyze the pore size distribution, zeta potential at varying pH levels, and thermostability using thermogravimetric analysis. These adsorbents exhibited high As(III) removal efficiency with a uniform pore distribution. The zeta potentials were observed to decrease with an increase in pH, suggesting a relationship between adsorbent charge and pH. Adsorption dynamics were rigorously modeled using pseudo-first-order, pseudo-second-order, Elovich, and intraparticle diffusion models for different adsorbents labeled as a,b,c, and d. Each adsorbent displayed unique fitted parameters, revealing varied adsorption capabilities. The study further explored the adsorption kinetics and found that the pseudo-second-order kinetics model and the Langmuir model were most appropriate for describing the adsorption process. Adsorption thermodynamics was also fitted to elucidate the underlying adsorption mechanisms. For the a,b,c, and d adsorbents, the pseudo-first-order model, the qe(cal) values for the four adsorbents were 434.2, 418.4, 283.5, and 279.5 μg/g, respectively. Take adsorbent a as an example; the qm values for 298, 303, 308, and 313 K were 702, 673, 605, and 589 μg/g, respectively, and KL values of these temperatures were 0.021, 0.031, 0.018, and 0.009 L/μg, respectively. For the Langmuir model, the R2 values at the four temperatures were 0.999, 0.978, 0.985, and 0.993, respectively, which indicated that the Langmuir model showed higher fitness. For the Freundlich model, the KL values (L/μg) at the parameters of these temperatures are 432, 409, 328, and 294, respectively. For the Freundlich model, the 1/n values at temperatures of 298, 303, 308, and 313 K are 0.049, 0.045, 0.052, and 0.035, respectively. For the Freundlich model, the R2 values at parameters of 298, 303, 308, and 313 K are 0.986, 0.989, 0.982, and 0.872, respectively. For the Temkin model, the B values (in J/mol) are 30.93, 0.894, 0.824, and 0.782 at these temperatures, respectively. The KT values (in L/μg) are 1.02 × 106, 0.07 × 106, 0.003 × 106, and 0.002 × 106, respectively. The R2 values are 0.973, 0.958, 0.972, and 0.894, respectively. In the end, the ΔH, ΔS, and ΔG values for different adsorbents were calculated. Collectively, these findings contribute significant insights into the design and application of magnetically activated carbon adsorbents for effective As(III) removal.

Retention of methyl iodide on metal and TEDA impregnated activated carbon using indigenously developed setup

Removal of methyl iodide (CH3I) from the air present within nuclear facilities is a critical issue. In case of any nuclear accident, there is a great need to mitigate the radioactive organic iodide immediately as it accumulates in human bodies, causing severe consequences. Current research focuses on removing organic iodides, for which the surface of activated carbon (AC) was modified by impregnating it with different metals individually, i.e. Ag, Ni, Zn, Cu and with the novel combination of these four metals (AZNC). After the impregnation of metals, triethylenediamine (TEDA) was coated on metal impregnated activated carbon (IAC) surface. The adsorption capacity of the combination of four metals IAC was found to be 276 mg/g as the maximum for the trapping of CH3I. Whereas TEDA-metal impregnation on ACs enhanced the removal efficiency of CH3I up to 352 mg/g.After impregnation, adsorption capacity of AZNC and AZNCT is significantly higher as compared to AC. According to the finding, t5% of AZNCT IAC is 46 min, which is considerably higher than the t5% of other tested adsorbents. According to isotherm fitting data, Langmuir isotherm was found superior for describing CH3I sorption onto AC and IACs. Kinetics study shows that pseudo second order model represented the sorption of CH3I more accurately than the pseudo first order. Thermodynamic studies gave negative value of ΔG which shows that the reaction is spontaneous in nature. Based on the findings, AZNCT IAC appears to have a great potential for air purification applications in order to obtain clean environment.

Comparison of structural properties and removal behavior of composites containing chitosan and hexagonal boron nitride in different compositions

ABSTRACT This study aims to prepare different possible composites using hBN and chitosan in varying ratios and compare them with each other. Composites c/hBN:100/0, c/hBN:75/25 and c/hBN:50/50 were prepared in varying mass ratios. Depending on the changing mass composition, the characterization results are presented in comparison with each other. The surface structures were observed by SEM analysis. FTIR analysis was used for functional group determination. Surface and pore identification was carried out by BET analysis. Crystalline formations were revealed by XRD analysis. True density values were determined by pycnometric analysis. Also, the RB 49 dye removal behavior of the composites was examined and compared with each other. c/hBN:100/0 and c/hBN:75/25 showed the highest removals at pH 4 and as 86.53 and 90.2%, respectively, while c/hBN:50/50 showed it at pH 3 and as 86.59%. The highest adsorption capacities were determined as 105.28, 160.71 and 159.01 mg/g for c/hBN:100/0, c/hBN:75/25 and c/hBN:50/50, respectively at 0.3 g/L dosage. The pseudo-second-order kinetic model and intraparticle diffusion model fitted well with the processes over time. The Freundlich isotherm model was found to be compatible with the processes. The positive ΔH and ΔS values and negative ΔG values of each process were presented.

Understanding the sorption behavior of tri, tetra and hexavalent f cations on metal–organic framework (MOF), ZIF-67: experimental and theoretical investigation

ABSTRACT Metal–organic frameworks (MOFs) are a class of compounds with modern-age technological importance due to diverse structural topologies, porosity, and modularity. ZIF-67 has been synthesized for efficient extraction of f cations in different oxidation states (UO2 2+, Th4+ and Eu3+) from aqueous pH medium exhibiting the trend in sorption efficiency as: Kd Th(6.19 × 103) > Kd U (5.20 × 103) > Kd Eu (1.58 × 103) in accordance to their chemical potential. Langmuir isotherm was found to be predominate with sorption capacity 85.9 mg g−1, 137.4 mg g−1 and 50.6 mg g−1 for U, Th and Eu, respectively. The sorption predominantly proceeded via pseudo 2nd order rate kinetics with rate constants: k2 U ~0.089 g mg−1 min−1, k2 Th ~0.011 g mg−1 min−1 and k2 Eu ~0.04 g mg−1 min−1. The processes were found to be spontaneous as revealed from negative ΔG values; and endothermic in nature (ΔHU ~10.5 kJ mol−1; ΔHTh ~12.8 kJ mol−1; ΔHEu ~8.3 kJ mol−1). The sorption proceeded via the formation of an inner sphere complex as indicated from their enhancement in the entropy values on sorption due to the release of water molecules. The Density Functional Theory (DFT) predicted selectivity using binding energy (ZIF-67-Eu3+ ~ -60.90 eV, ZIF-67-Th4+ ~ -70.78 eV, ZIF-67-Th4+ ~ -69.52 eV) is in line with the experimental selectivity of Th4+ > UO2 2+ > Eu3+. Total density of states (TODS) and Projected density of States (PODS) were estimated in order to understand the interaction between the ZIF-67 and f cations.

Synthesis of High-Crystallinity Mg-Al Hydrotalcite with a Nanoflake Morphology and Its Adsorption Properties for Cu2+ from an Aqueous Solution

A magnesium–aluminum-layered double hydroxide (Mg-Al LDH) with a nano-lamellar morphology was prepared by using a homogeneous precipitation and hydrothermal method, and a calcination product (Mg-Al LDO) of the Mg-Al LDH was also obtained in this work. The XRD, TEM, SEM, FTIR, N2 ad/desorption, and TG-DTG techniques were employed to characterize the microstructures, morphologies, and thermostability levels of these two materials in detail. The results showed that both the Mg-Al LDH and Mg-Al LDO had mesoporous structures and nanoplate morphologies, with diameters of 50~200 nm. The Mg-Al LDH was transformed into Mg-Al LDO at 773 K in an air atmosphere. The adsorption properties of the Mg-Al LDH were investigated systematically with a copper chloride solution as a simulated waste. The experimental results demonstrated that the pH value of the solution had an obvious influence on its Cu2+ adsorption capacity, and the optimal pH value was approximately 5.0. The adsorption kinetics results showed that the Mg-Al LDH had a rapid adsorption rate, and the equilibrium adsorption capacity was 62.11 mg/g. Additionally, the Cu2+ adsorption could be commendably described using a pseudo-second-order model, demonstrating that the adsorption behavior is regulated by chemical sorption. The adsorption thermodynamic results indicated that the adsorption process was spontaneous at temperatures above 318 K. Moreover, the ΔG0 values decreased as the temperature was raised, which indicated that a higher temperature can cause a greater impetus for Cu2+adsorption. In addition, the positive values of the ΔH0 indicated that the Cu2+ adsorption was endothermic, and the positive ΔS0 values revealed an increase in the confusion at the solid–liquid interface of the adsorbent.

A Novel Rhipicephalus microplus Estrogen Related Receptor (RmERR), a Molecular and In Silico Characterization of a Potential Protein Binding Estrogen.

The search for targets to control ticks and tick-borne diseases has been an ongoing problem, and so far, we still need efficient, non-chemical alternatives for this purpose. This search must consider new alternatives. For example genomics analysis is a widely applied tool in veterinary health studies to control pathogens. On the other hand, we propose that regulation of endocrine mechanisms represents a feasible alternative to biologically controlling tick infestations. Thus, we performed the molecular identification of an estrogen-related receptor gene of Rhipicephalus microplus called RmERR by RT-PCR in tick ovaries, embryonic cells, and hemolymph, which allowed us to analyze its expression and propose potential functions in endocrine mechanisms and developmental stages. In addition, we performed an in silico characterization to explore the molecular interactions of RmERR with different estrogens, estrogenic antagonists, and endocrine disruptor Bisphenol A (BPA), finding potential interactions predicted by docking analysis and supported by negative values of ΔG (which suggests the potential interaction of RmERR with the molecules evaluated). Additionally, phylogenetic reconstruction revealed that RmERR is grouped with other tick species but is phylogenetically distant from host vertebrates' ERRs. In summary, this study allowed for the identification of an ERR in cattle tick R. microplus for the first time and suggested its interaction with different estrogens, supporting the idea of a probable transregulation process in ticks. The elucidation of this interaction and its mechanisms unveiled its potential as a target to develop tick control strategies.

Curcumin-loaded hydroxyapatite nanoparticles for enriched removal of organic pollutants and inhibition of dual-species biofilm formation

The resistance of staphylococcus aureus and Acinetobacter baumannii to antimicrobial agents results in chronic infections, making removing contaminants from wastewater essential for environmental remediation. Removing hazardous pollutants from wastewater and inhibiting biofilm formation is important for environmental remediation. This study effectively built biocompatible curcumin-loaded hydroxyapatite nanoparticles (Cur-HAp NPs) using a simple in-situ precipitation technique. Various analytical characterization techniques were used to evaluate the structural, morphological, and chemical composition of the synthesized NPs. Combining a highly bioactive natural curcumin pigment with hydroxyapatite NPs could maintain its pharmacological activity and exhibit a sustained release profile of curcumin. The antibiofilm activities against single and mixed dual species of S. aureus and A. baumannii were evaluated using crystal violet staining techniques. Excellent antibiofilm activities were demonstrated by Cur-HAp NPs against S. aureus, A. baumannii, and mixed dual species, with respective efficiency percentages of 76.7, 85.6, and 68.8 % inhibition upon treatment, respectively. In addition, Cur-HAp NPs demonstrated excellent dye adsorption against Congo red dye by approximately 95.6 %. Cur-HAp could absorb up to 112.4 mg/g of dye at a time. Negative ΔG value (−1.372 kJ mol−1) indicates the spontaneous and feasible dye absorption onto Cur-HAp. The Langmuir adsorption isotherm and pseudo-second-order equation provided the best fit for the Cur-HAp NPs. Therefore, the sustained drug release behavior of Cur-HAp NPs is a promising candidate for combatting antibiofilm activity and dye removal capacity.

Combustion, kinetics and thermodynamic characteristics of rice husks and rice husk-biocomposites using thermogravimetric analysis

AbstractPyrolysis of rice husk (RH), alkali-treated cellulose-rich rice husk (RHC), chemically modified RHC (RHCM) and RH-biocomposites by thermogravimetric analysis was carried out to determine combustion and kinetic parameters at three different heating rates of 20, 40 and 50 °C min−1. Combustion performance was analyzed from results of ignition temperature, burnout temperature, combustion rates, flammability index and combustion characteristic index. Increase in heating rate from 20 to 40 and further to 50 °C min−1 increased the onset of degradation, burnout and peak temperatures as observed by curve shifts to the right. Maximum combustion rates were around 0.57–0.59% min−1, 1.03% min−1 and 0.63–0.69% min−1 for RH, RHC and RHCM, respectively. For the RH-biocomposites, the maximum combustion rates were in a 0.76–0.97% min−1 range. Their average pre-exponential factors using KAS method were in the 2.24E-03–8.07E-03 range, respectively, while those for OFW method were in the 7.75E + 04–4.55E + 06 range, respectively. Average activation energies of RH-biocomposites were in the 41.0–58.2 kJ mol−1 and 48.3–67.7 kJ mol−1 ranges for KAS and OFW methods, respectively. The data were well fitting with coefficient of determination (R2) values close to 1. Average ΔG value ranges for RH-biocomposites ranged between 148.2 and 161.7 kJ mol−1. The low-energy barrier (≤ 5.4 kJ mol−1) between activation energy and enthalpy changes indicated that reaction initiation occurs easily.

Interaction of sodium alginate biopolymer with sodium dodecyl sulfate in aqueous medium and different additive solutions at several temperatures

Interactions between sodium dodecyl sulfate (SDS) and sodium alginate (NaAlg) in aq. salts/hydrotrope (HDT) media have been investigated using conductivity method with changing the micellar parameters (e.g., critical micelles concentration (CMC), extent of micelle ionization (α), and bound counterions (β)) and thermodynamics of the micellization of SDS + NaAlg mixtures. CMC values and α were assessed from the plots of conductivity versus [SDS]. The micellization of SDS + NaAlg was enhanced in aq. electrolyte and aq. HDTs media. The formation of SDS + NaAlg micelles was found to happen delayed with an increase in temperature in water and aq. 10% (w/w) glycerol (GLY) solution, while in other employed solvents, micelle creation was observed to favor with an upsurge of working temperature. Thermodynamics of SDS + NaAlg mixtures were computed from temperature dependency of CMC. The values of ΔG 0 m were found negative for all the experiments, thereby, examined. The values of Δ H m 0 in the micellization of SDS + NaAlg mixtures in H2O, H2O + sodium acetate (NaOAc), H2O + sodium benzoate (NaBenz), and H2O + 4-amino benzoic acid (4-ABA) media were observed positive, and, hence, the process was endothermic in these solvents. Micellization of SDS + NaAlg was exothermic in 10% (w/w) glycerol (GLY) solutions at all temperatures and in H2O + NaCl at 298.15 and 303.15 K. The values of Δ H m 0 and Δ S m 0 for SDS + NaAlg show that the hydrophobic, van der Waals and exothermic interactions are the driving forces between SDS and NaAlg in electrolytes and HDT media.

Adsorption of Rose Bengal dye from waste water onto modified biomass

Herein, adsorption of Rose Bengal dye (RB) from aqueous solution was investigated. Nano raw orange peel (OP) activated carbon (AC) coated with nano chitosan (Cs) to obtain nano chitosan/activated carbon (AC/Cs) composite which cross-linked with functionalized multi-walled carbon nanotubes (MWCNTs-COOH) to create a novel composite (AC/Cs/MWCNTs) with high surface area (1923 m2/g). The examined parameters such as concentration (1–7 ppm), pH (6.5–9.5) and temperature (295–323 K) were traversed. The maximum removal efficiency was at pH 6.5, increased from 70.4% for nano OP to 94.7% for AC/Cs/MWCNTs nano composite. Langmuir isotherm model was the best fitting to acquired data (R2 ≥ 0.99). Also, the adsorption of RB matched with pseudo-second order model, t0.5 results for pseudo-second order was 4.4672 for nano OP and 1.2813 for AC/Cs/MWCNTs at 303 K. Thermodynamic studies showed that the adsorption of RB dye is exothermic and spontaneous due to the negative value of ΔG and ΔH.

Binding interactions of Vildagliptin with pepsin: A multi-spectroscopic and in-silico approach and a comparative account with metformin

Vildagliptin (VDG) and Metformin (Met) belong to a class of dipeptidylpeptidase-4 (DPP-4) inhibitor and biguanide, respectively and used for the management of diabetes mellitus type II (DMTII). Both the drugs are orally available which leads to various side effects due to its oral ingestion. Occurrence of these side effects might be due to some interactions with pepsin at a molecular level. Therefore, in order to investigate these interactions, multi-spectroscopic and in-silico techniques have been extensively studied to identify the binding characteristics of VDG with pepsin. Fluorescence data suggested that the quenching is due to dynamic and static mechanism and static was dominant one. However, fluorescence and UV–Vis spectroscopic measurement analysis suggested that VDG tends to associate with pepsin, via ground-state complex formation. Fluorescence study revealed the binding-constant value which was found to be 0.559 × 103 M−1 at 298.15 K that is non-covalent in nature. VDG-pepsin complex shows exothermic and spontaneous binding as confirmed by the calculated values of ΔH, ΔS, and ΔG, are majorly caused by van der Waals forces and H-bonding interactions. CD spectra of pepsin in presence of VDG confirmed post binding conformational change. Enzyme-activity assay showed that activity of pepsin was decreased by upto 28 %. FRET analysis suggested that energy transfer efficiency is negligible for VDG-pepsin interaction. In-silico analysis reveals that H-bonding and electrostatic negative forces are the significant driving forces involved in the interaction of VDG and pepsin.

Preparation of Cationic Composite Hydrogel Improved by Activated Carbon and Its Use in Removal of Anionic Dye

Water-insoluble p(AETAC)/AC composite hydrogels containing quaternary ammonium were prepared by free-radical polymerisation method with [2-(Acryloyloxy)ethyl]trimethylammonium chloride (AETAC) and activated carbon (AC). The composite hydrogel was characterized by Fourier Transform Infrared Spectroscopy (FT-IR), Thermogravimetric analysis (TGA), X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM) methods. In addition, the swelling behavior of p(AETAC)/AC composite hydrogels containing 50 mg, 75 mg, 100 mg, and 150 mg AC in deionized water was investigated. The swelling capacity of the p(AETAC)/AC75 composite hydrogel containing 75 mg AC in various waters was determined. Initial dye concentration, contact time, pH of dye solution, amount of adsorbent, and temperature parameters affecting MO adsorption of p(AETAC)/AC75 composite hydrogel were investigated. The obtained adsorption data agree with the Langmuir isotherm model and the PFO kinetic model. It was determined that the maximum adsorption ability of p(AETAC)/AC75 composite hydrogel according to Langmuir isotherm was 909.09 mg/g. ΔH° and ΔS° values for the adsorption of MO dye-stuff of p(AETAC)/AC75 composite hydrogel were calculated as 22.25 ± 1.43 and 85.40 ± 4.60, respectively. In addition, the value of ΔG° less than zero at four different temperatures indicates that the dye adsorption is spontaneous. According to all the data obtained, p(AETAC)/AC75 composite hydrogel can be considered a promising candidate for the removal of anionic dyestuffs from water.

Synthesis of N-aminophalimides derived from α-amino acids: Theoretical study to find them as HDAC8 inhibitors by docking simulations and in vitro assays.

Phthalimides are valuable for synthesis and biological properties. New acetamides 3(a-c) and 4(a-c) were synthesized and characterized as precursors for novel N-aminophalimides 5(a-c) and 6(a-c). Structures of 4a, 5(a-b), and 6(a-b) were confirmed by single crystal X-ray. Docking studies identified compounds with favorable Gibbs free energy values for binding to histone deacetylase 8 (HDAC8), an enzyme targeted for anticancer drug development. These compounds bound to both the orthosteric and allosteric pockets of HDAC8, similar to Trichostatin A (TSA), an HDAC8 inhibitor. 6(a-c) contain hydroxyacetamide moiety as a zinc-binding group, a phthalimide moiety as a capping group, and aminoacetamide moiety as a linker group, which are important for ligand-receptor binding. ΔG values indicated that compounds 5b, 6b, and 6c had higher affinity for HDAC8 in the allosteric pocket compared to TSA. In vitro evaluation of inhibitory activities on HDAC8 revealed that compounds 3(a-c) and 5(a-c) showed similar inhibitory effects (IC50 ) ranging from 0.445 to 0.751 μM. Compounds 6(a-c) showed better affinity, with 6a (IC50 = 28 nM) and 6b (IC50 = 0.18 μM) showing potent inhibitory effects slightly lower than TSA (IC50 = 26 nM). These findings suggest that the studied compounds hold promise as potential candidates for further biological investigations.

Design a promising electro-catalyst for oxygen reduction reaction in fuel cells based on transition metal doped in BN monolayer

The kinetic of the oxygen reduction reaction (ORR) at the cathodes of polymer-electrolyte-membrane fuel cells (PEMFCs) has been demonstrated to be slow, which is one of the pivotal issues in developing PEMFCs. Within the current piece of research, by performing first-principles calculations, we introduce a Co-doped vacancy BN nanosheet (Co-HBN) as an efficacious noble metal-free electro-catalyst for the ORR process (ORRP) in fuel cells. The results demonstrate a rise in the energies of adsorption (or adhesion) onto the Co–N active site of these electrocatalysts in the order of O < OH < OOH < O2 < H2O2 < H2O on this electrocatalyst and there is a consistent change in the adsorption energies (Eads)for all oxygen-containing intermediates (OCIs). Based on the small and large thermodynamic driving force for the generation of H2O2 and for reducing OOH into O∗ (or to 2OH∗), respectively, the four-electron route was more favorable in comparison with the 2e− route. Furthermore, with the largest value of ΔG for Co-HBN electrocatalyst, the final reduction step (OH∗ + H+ + e− → H2O + ∗) has been regarded as the rate-limiting step. The d-band center of Co was considerably distant from the Fermi level. The greater gap between the frontier orbitals suggested that the electrocatalyst is not conducive to the adsorption of OCIs, which shows that the onset potential is larger and ORR is high.

Adsorption of Methylene Blue Dye by Cetyltrimethylammonium Bromide Intercalated Polyaniline-Functionalized Montmorillonite Clay Nanocomposite: Kinetics, Isotherms, and Mechanism Study.

In this study, new adsorbents were prepared by modifying a montmorillonite clay (Mt) with cethyltrimethyl ammonium bromide (CTAB) to form CTAB-Mt, followed by a second modification process with polyaniline (PAni) to form PAni@CTAB-Mt by in situ polymerization of aniline. X-ray diffraction (XRD), X-ray fluorescence spectroscopy (XRF), X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), cyclic voltammetry (CV) and the Brunauer-Emmett-Teller (BET) technique were used to characterize the samples. These adsorbents were used in a batch process to remove methylene blue (MB) from aqueous solution. Factors investigated included initial pH of the solution, contact time and temperature. The adsorption data fit the Freundlich isotherm better than the Langmuir and Temkin isotherms. The maximum adsorption capacities (qeq) obtained were 108.82 mg·g-1, 71.20 mg·g-1 and 57.36 mg·g-1 for PAni@CTAB-Mt, CTAB-Mt and Mt, respectively. The enhanced adsorption capability of the hybrid material is due to increase in surface area and pore volume of the PAni@CTAB-Mt adsorbent. The adsorption results were found to fit well with the pseudo-second-order kinetics model, with highest correlation coefficient (R2) values of 0.954, 0.942 and 0.958 for Mt, CTAB-Mt and PAni@CTAB-Mt adsorbents, respectively. The pH and temperature had a significant effect on the adsorption process, and the negative values of ΔG suggest that the adsorption process was spontaneous and feasible. The desorption and reusability experiment indicated that PAni@CTAB-Mt has the potential to be a reusable adsorbent for MB removal.

Application of sawdust particles modified by in situ surface polymerization of m-phenylenediamine and its by-product: Batch and continuous removal of Cr(VI)

The primary objective of this research was to synthesize an adsorbent for Cr(VI) removal using a simple synthesis method that involved the use of KMnO4 for the surface activation of sawdust in which the polymerization of m-Phenylenediamine (mPD) can take place directly on the surface of the adsorbent. The adsorbent's surface morphology was assessed using various techniques including FESEM, EDS, FT-IR, and XRD. The optimal adsorbent was prepared by synthesizing different adsorbents under various KMnO4/sawdust and PmPD/sawdust mass ratios and the best performance was obtained at ratios of 1 and 0.6 respectively. Batch experiments were conducted at optimal conditions (pH = 2, adsorbent dosage of 2 g L−1, contact time of 50 min) and removal efficiency of 90.28% was achieved at a Cr(VI) concentration of 100 mg L−1. The Langmuir isotherm model provided the most accurate fitting to the experimental data, resulting in the maximum adsorption capacity of 62.11 mg g−1. The interparticle diffusion model presented the most precise fitting to the experimental values. The positive value ΔH° and negative values ΔG° prove that the adsorption reactions are endothermic and spontaneous. To assess the effectiveness of PmPD/MnO2/sawdust in removing Cr(VI) at dynamic scales, column experiments were carried out at various flow rates and initial Cr(VI) concentrations. Also, the MnO2 particles obtained after the oxidation of sawdust were functionalized using the mentioned process, and the value of adsorption capacity was determined as 270.27 mg g−1. The easy separation, and full-scale applicability showed a promising application of sawdust/MnO2/PmPD for Cr(VI) removal from aquatic environments.