Aqueous Research Articles

Isotherms, kinetics and thermodynamic sorption of paranitroaniline on Cocos nucifera shell activated carbon@TiO2 composite

AbstractA comparative study was conducted on the adsorption capacity of Cocos nucifera shell‐activated carbon (CNSA) and Cocos nucifera shell‐activated carbon@TiO2 composite (CNSA‐TiO2) for para‐nitroaniline in an aqueous medium. The CNSA was carbonized at 500 °C and activated with 1 M HNO3 while the CNSA‐TiO2 composite was prepared by wet impregnation method. The prepared adsorbents were characterized through Brunauer–Emmett–Teller (BET), energy dispersive X‐ray (EDX) spectroscopy, Fourier‐transform infrared (FTIR) spectroscopy, and scanning electron microscopy (SEM). The BET‐surface area of CNSA‐TiO2 (748.96 m2/g) was established to be larger than CNSA (574.21 m2/g), however both materials are mesoporous. The effects of initial p‐NA concentration, pH, adsorbent dosage, contact time, and temperature, were explored for both adsorbents. The results showed that the adsorption operating parameters influenced the adsorption process except for temperature, with maximum adsorption of 38.26 and 38.36 mg/g for CNSA and CNSA‐TiO2, respectively. Freundlich, Langmuir, Temkin, and Dubinin‐Radushkevich isotherms were tested on the adsorption data, and the adsorption process of both adsorbents followed the Freundlich isotherm model (R2 > 0.988). Among the kinetic models studied, the pseudo‐second‐order model (R2 = 1) best described both processes. The thermodynamic parameters such as ∆G °, ∆H ° and ∆S ° were calculated. The process was exothermic, spontaneous and feasible.

Synthesis and characterization of polyacrylamide-based antibacterial hydrogel nanocomposite

ABSTRACT In this research, the hydrogel nanocomposites based on acryl amide containing penicillin 800, 1200, Ag, and ZnO nanoparticles as wound dressing applications have been studied. In this work, the preparation was done via a reaction of optimal values to produce an antibacterial hydrogel nanocomposite. The hydrogel was obtained in an aqueous medium by using reagents such as acrylamide, potassium persulfate, and methylene bisacrylamide crosslinker, Ag, ZnO nanoparticles, and penicillins and then, the products were dried as white powders. The properties such as swelling rate, pH sensitivity, and high water swelling capacity of the swelling rate study of the hydrogel showed a high absorption rate of water in pH about 3–4. The effect of temperature on the percentage of hydrogel swelling was shown to swell with increasing temperature and the absorption capacity of polyacrylamide hydrogels decreased with increasing NaCl concentration. The chemical structure of hydrogel was confirmed by FTIR spectrum, and the morphology of synthesized hydrogel surfaces was studied via SEM. The antibacterial studies were done in blood, agar, chocolate, and Müller medium via three methods, first on gram-negative bacteria E. coli and Klebsiella, second in urine medium, and third in drug medium. This polymeric blend can be used as a new wound dressing compound.

Modifying the Resistant Starch Content and the Retrogradation Characteristics of Potato Starch Through High-Dose Gamma Irradiation

Potato starch is widely utilized in the food industry. Gamma irradiation is a cost-effective and environmentally friendly method for starch modification. Nevertheless, there is a scarcity of comprehensive and consistent knowledge regarding the physicochemical characteristics of high-dose gamma-irradiated potato starch, retrogradation properties in particular. In this study, potato starch was exposed to gamma rays at doses of 0, 30, 60, 90, and 120 kGy. Various physicochemical properties, including retrogradation characteristics, were investigated. Generally, the apparent amylose content (AAC), water absorption, gel viscosity, gel hardness, and gumminess decreased as the doses of gamma irradiation increased. Conversely, the resistant starch (RS), amylose content evaluated by the concanavalin A precipitation method, water solubility, and enthalpy of gelatinization were increased. Additionally, swelling power, crystalline structure, and amylopectin branch chain length distribution either remained stable or exhibited only minor changes. Notably, the degree of retrogradation of potato starches on day 7 was positively correlated with the doses of gamma irradiation.

Desorption of Antibiotics from Granular Activated Carbon during Water Treatment by Adsorption

Although desorption of adsorbed pharmaceuticals from granular activated carbon (GAC) may inadvertently lead to their partial discharge with adverse effects on aquatic environments, there have only been a few reports of this phenomenon. This study has investigated desorption of antibiotics vancomycin and rifampicin from activated carbon in aqueous media regarding contact time and pH regime. Various characterizations of the three types of GAC were investigated. Then, antibiotics were loaded on them via adsorption. Subsequently desorption and re-adsorption of antibiotics were quantified for a range of contact times and ambient pH values. Within the first hour of a reversed concentration gradient at neutral pH, desorption released 2% to 54% of previously adsorbed antibiotics to water, which were subsequently re-adsorbed within 24 hours to four weeks with less than 1% antibiotics remaining in the liquid phase. Lower desorption was positively associated with higher GAC mesopore content and larger specific surface area. Effects of the ambient pH regime varied between studied adsorbents. The results are evidence that mesopore content and pore size in relation to the kinetic diameter of adsorbate molecules are important determinants of the extent of antibiotic desorption from GAC and the rates of subsequent re-adsorption. Physisorption was the dominant mechanism involved in both processes. Observed proportions and rates of antibiotic desorption suggest that selection of GAC properties should also consider their effects on unintended desorption and the re-adsorption during treatment processes in order to minimize potential pollution discharge or promotion of antibiotic resistance during treatment processes.

Preparation and Characterization of Poly(acrylic acid-co-vinyl imidazole) Hydrogel-Supported Palladium Catalyst for Tsuji–Trost and Suzuki Reactions in Aqueous Media

In this study, a novel polyacrylate-co-vinyl imidazole hydrogel-supported palladium (Pd) catalyst (P(AA-co-VI)@Pd) was prepared through heat-initiated polymerization, starting with the formation of a complex between vinyl imidazole and palladium chloride, followed by the addition of 75% neutralized acrylic acid (AA), crosslinking agent, and initiator. The structure and morphology of the catalyst were characterized using ICP-OES, SEM, EDX, Mapping, FT-IR, TGA, XRD, XPS and TEM techniques. It was confirmed that the catalyst exhibited excellent compatibility with water solvent and uniform distribution of Pd. The P(AA-co-VI)@Pd hydrogel catalyst demonstrated remarkable catalytic activity and ease of separation. Notably, in a Tsuji–Trost reaction, employing water as the solvent, it achieved a conversion rate as high as 94% at very low catalyst dosages, indicating its superior catalytic performance. Moreover, after six consecutive cycles, the catalyst maintained good activity and structural stability, highlighting its exceptional reusability and environmental friendliness. Furthermore, the outstanding efficiency of the catalyst was also observed in a Suzuki coupling reaction where both conversion rate and yield reached 100% and 99%, respectively, within just one hour reaction time, thus further validating its universality and efficacy across various chemical reactions.

SBA-Pr-IS-MN-DM: a new fluorescent chemosensor for trace detection of silver in aqueous solutions

Initially, SBA-Propyl-Isatin-Malononitrile (SBA-Pr-IS-MN) was prepared by the reaction of SBA-Pr-Cl with IS-MN, which was synthesized by the reaction of isatin and malononitrile. This organic and inorganic hybrid material can be functionalized by the sequential reaction with dimedone to obtain the target product SBA-Pr-Is-MN-DM, which was investigated as a chemosensor by fluorescence spectroscopy to detect trace amount of Ag+ among several other cations in aqueous media.

Development of Variable Charge Cationic Hydrogel Particles with Potential Application in the Removal of Amoxicillin and Sulfamethoxazole from Water

Cationic hydrogel particles (CHPs) crosslinked with glutaraldehyde were synthesized and characterized to evaluate their removal capacity for two globally consumed antibiotics: amoxicillin and sulfamethoxazole. The obtained material was characterized by FTIR, SEM, and TGA, confirming effective crosslinking. The optimal working pH was determined to be 6.0 for amoxicillin and 4.0 for sulfamethoxazole. Under these conditions, the CHPs achieved over 90.0% removal of amoxicillin after 360 min at room temperature, while sulfamethoxazole removal reached approximately 60.0% after 300 min. Thermodynamic analysis indicated that adsorption occurs through a physisorption process and is endothermic. The ΔH° values of 28.38 kJ mol−1, 12.39 kJ mol−1, and ΔS° 97.19 J mol−1 K−1, and 33.94 J mol−1 K−1 for AMX and SMX, respectively. These results highlight the potential of CHPs as promising materials for the removal of such contaminants from aqueous media.

Combinatorial MD/QM studies to develop novel ionic liquid-based anticancer drug delivery systems with aminium derived from carbohydrates as cationic components

The main challenges in anticancer drug design include solubility in organic and aqueous phases, bioavailability, selective targeting of specific receptors, and low toxicity. Notably, solubility, bioavailability, and receptor-specific targeting are interconnected factors that significantly influence the therapeutic efficacy of anticancer drugs. The primary objective of this study is to design novel drug delivery systems based on ionic liquids. These systems incorporate structures such as N, N, N-trimethyl-2-(((2 S,3R,4 S,5 S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)tetrahydro-2 H-pyran-2-yl)oxy)ethan-1-aminium (GTA) and (2 S,3R,4 S,5 S,6R)-3,4,5-trihydroxy-6-(hydroxymethyl)-N, N, N-trimethyltetrahydro-2 H-pyran-2-aminium (NTPA) derived from carbohydrates as cationic components, with anticancer drugs acting as anions. The goal is to investigate the effects of these novel pharmaceutical active ionic liquids on the interactions between the drugs and cell membranes. Additionally, this study examines changes in the solubility of anticancer drugs in both organic and aqueous phases after their conversion into ionic liquids. Molecular dynamics simulations (MD) and quantum mechanics calculations (QM) are employed to achieve these objectives. Known anticancer-candidate ionic liquid, such as 3-(2-((4-fluorophenyl)amino)-2-oxoethyl)-1-methyl-1 H-imidazol-3-ium-tetrafluoroborate, is considered as a reference point in our investigations. Furthermore, we aim to assess whether the direct attachment of the aminium group to the saccharide portion of the cations or the indirect attachment through a choline group significantly impacts the final properties of the designed anticancer ionic liquids. Another aim of this study is to demonstrate that QM studies need to be complemented by MD studies to provide insights into the behaviors of ionic liquids. Initially, we calculate the binding energies between cations and anions of all the ionic liquids at the B3LYP/6-311 + + G(d, p) level of theory. Subsequently, molecular dynamics simulations using GROMACS 5.2 are employed to obtain more precise information about these understudied ionic liquids. A combination of density functional theory (DFT) calculations and a solvation model based on density (SMD) is utilized to determine the solubility of free anticancer drugs and our active anticancer ionic liquids in various phases. We validate our findings by evaluating the interactions between the formulated ionic liquids and cell membranes using the DPPC model through combined MD simulations and docking procedures.

Mechanically strong yet metabolizable supramolecular plastics by desalting upon phase separation.

Plastics that can metabolize in oceans are highly sought for a sustainable future. In this work, we report the noncovalent synthesis of unprecedented plastics that are mechanically strong yet metabolizable under biologically relevant conditions owing to their dissociative nature with electrolytes. Salt-bridging sodium hexametaphosphate with di- or tritopic guanidinium sulfate in water forms a cross-linked supramolecular network, which is stable unless electrolytes are resupplied. This unusual stability is caused by a liquid-liquid phase separation that expels sodium sulfate, generated upon salt bridging, into a water-rich phase. Drying the remaining condensed liquid phase yields glassy plastics that are thermally reshapable, such as thermoplastics, and usable even in aqueous media with hydrophobic parylene C coating. This approach can be extended to polysaccharide-based supramolecular plastics that are applicable for three-dimensional printing.

Comparison of Low Temperature Methanol Aqueous Phase Reforming Catalysts─Definition of Standardized Reaction Conditions and Considerations toward Applications

Comparison of Low Temperature Methanol Aqueous Phase Reforming Catalysts─Definition of Standardized Reaction Conditions and Considerations toward Applications

Comparison of technological and physical properties of matcha powders of different geographical origins.

The sorption characteristics and glass transition temperature are important attributes that determine the shelf life of foods, particularly in powder form, whereas color is a key factor influencing consumer acceptance. As the popularity of matcha green tea powder is increasing, this study investigated whether the country of origin of examples of matcha products available on the Polish market influenced the sorption properties, glass transition temperature, and color. All matcha powders exhibited sigmoidal water adsorption isotherms at 25 °C. The monolayer moisture content corresponding to the point of maximum stability ranged from 0.045 to 0.053 g water per g of sample. The glass transition temperature of anhydrous matcha powders varied between 106.3 and 139.0 °C. Based on the sorption and glass transition results, the matcha from Brazil should be the most stable during storage. The same sample showed the highest water solubility index values at temperatures above 80 °C and the lowest bulk density. The color parameters (L*, a*, b*, C*, and h) depended on the matcha powder variant. The results indicate that the optimal storage conditions for tea powders do not depend directly on the country of origin. Further research should therefore focus on analyzing the impact of climate or fertilization. © 2024 Society of Chemical Industry.

Ultrasonic Mediated Synthesis of Dihydropyrano [2, 3-C] Pyrazole Derivatives Catalyzed By Cyanuric Acid/1-Methyl Imidazole

A Novel approach for the synthesis of dihydropyrano[2,3-c] pyrazoles via four-component reaction of ethyl acetoacetate, hydrazine hydrate, aromatic aldehydes and malononitrile at room temperature under ultrasound irradiation is described. The reaction has been catalyzed by cyanuric acid and 1-methyl inidazole in aqueous medium. This protocol afforded several advantages such as easily available catalyst, simple operational procedure, excellent yield and ultrasound irradiation.

The inclusion of guest molecules by pillar[n]arene hosts in nonaqueous solution

The inclusion of guest molecules by pillar[n]arene hosts in nonaqueous solution

Investigation of the adsorptive capacity of a poly(vinyl alcohol)-based film for sodium diclofenac in aqueous media

Sodium diclofenac (DCF) has been detected in waters worldwide and is considered a micropollutant of emerging concern due to its potential toxicity in aquatic and terrestrial ecosystems. Traditional water treatment methods are unable to remove DCF completely from water, which makes adsorptive films a suitable alternative to address this challenge. In this context, the present study investigated the adsorptive capacities of a poly(vinyl alcohol)-based film for removing DCF from aqueous solutions. The effects of the initial DCF concentration and solution pH on the adsorption performance were evaluated, as well as kinetics and equilibrium isotherms. Regarding the results, DCF precipitation was observed within a pH range of 4.0-7.0, probably due to its limited solubility in acidic media. The optimal DCF concentration was found to be the lowest tested (2.5 mg L-1), yielding an equilibrium adsorption capacity (qe) of 0.511 mg g-1 and a DCF removal percentage (%R) of 23.4% within 90 min. Although the adsorption equilibrium was well described by the Redlich-Peterson isotherm despite the unusual behavior observed, pseudo-first and pseudo-second order kinetic models were satisfactory only at the initial concentration of 2.5 mg L⁻¹. Overall, the data set indicate that the film has a limited adsorption capacity, reaching saturation at low adsorbate concentrations. Nonetheless, these findings support further investigations at lower DCF concentrations to better understand the film’s adsorptive behavior under environmentally relevant conditions.

Surface modification of heterostructured Bi8W4O24/ZrO2@GO composite via low-pressure cold plasma for boosting photocatalytic potential against Basic fuchsin and Bismarck brown Y dyes.

The widely used dyes, Basic fuchsin (BF) and Bismarck brown Y (BBY), pose significant risks to water resources and human health, necessitating efficient removal methods. Semiconductor-based heterogeneous photocatalysis offers an eco-friendly solution. However, improving the photocatalyst's efficiency remains a challenge. This study aims to fabricate a promising Bi8W4O24/ZrO2@GO (BWOZG) heterojunction via hydrothermal approach, followed by low-pressure cold plasma (LPCP) treatment to improve its properties for environmental remediation of BF and BBY dyes along with industrial wastewater. The prepared composites were analyzed via DLS, UV-visible spectroscopy, SEM-EDX, FTIR, XRD, and EPR. The findings indicated that the LPCP-treated BWOZG has z-average of 225 ± 5nm, zeta potential of - 38.74 ± 2mV, band gap of 2.20eV, a porous morphology, and mixed orthorhombic Bi8W4O24 and tetragonal ZrO2 phases. LPCP-treated BWOZG composite exhibited 5% increase in degradation efficiency of BF (99.7%) at pH = 6, catalyst dose = 20mg L-1, dye dose and irradiation time = 10mg L-1/30min, and 6% for BBY (98%) at pH = 5, catalyst dose = 30mg L-1, dye dose and irradiation time = 10mg L-1/30min, and 80.41% reduction in COD of industrial wastewater. The successful degradation of dyes to nontoxic species was confirmed by FTIR. The formation of •OH and O2-• radical species during photocatalytic process was confirmed by EPR analysis. Kinetics study showed the best fitness of the pseudo-first-order model on experimental data. LPCPT-BWOZG retained 91 and 89% recyclability after five cycles of BF and BBY degradation, respectively, and good broad-spectrum bactericidal activity for E. coli and S. aureus, demonstrating its potential as antibacterial photocatalytic materials for oxidation of organic pollutants in aqueous media to enhance the environmental safety.

Reimagining anti-inflammatory drugs delivery: the integration of ordered mesoporous silica and MOF materials for enhanced therapeutic outcomes

Abstract Migraine, one of the neurological conditions, affects approximately 15% of the global population. It is characterized by intense headaches accompanied by nausea, vomiting, and heightened sensitivity to light. The first line of drugs for treating migraine are non-steroidal anti-inflammatory drugs. Unfortunately, these medications suffer from poor solubility in water, uncontrolled release, and numerous adverse side effects. In order to maximize their therapeutic effect by preventing premature release and degradation, novel drug delivery systems based on composites are being dynamically developed. Herein, the biocompatible ketoprofen, naproxen sodium, and diclofenac sodium vehicles integrating ordered mesoporous silica (SBA-16) with Fe-based metal–organic frameworks (MIL-101(Fe)) were synthesized via the solvothermal method. The composites were characterized by different percentages of MIL-101(Fe) 
(25 and 50 wt.%), which had a significant impact on their porosity, structure, and number of functional groups. The SBA-16@MIL-101(Fe)-25 and SBA-16@MIL-101(Fe)-50 samples exhibited BET surface areas of 768 and 324 m2/g, respectively. Their sorption capacities towards selected anti-inflammatory drugs were in the range of 141-318 mg/g for ketoprofen, 481-490 mg/g for naproxen sodium, and 246-589 mg/g for diclofenac sodium, notably exceeding the values obtained for pure mesoporous silica (5-9 mg/g). Morphological defects and specific functional groups, derived from SBA-16 and MIL-101(Fe), contributed to generating new adsorption sites in composites, enhancing host-guest interactions. The drug release profiles were determined by the carrier porosity, surface charge, and the presence of functional groups. The diffusion of ketoprofen and diclofenac sodium from the composites into the phosphate buffer (pH 7.7), mimicking rectal fluid, occurred in a more controlled manner compared to pristine silica. The SBA-16@MIL-101(Fe)-50 carrier released 82% of ketoprofen and 90% of diclofenac sodium over 24 hours.

Highly Water-Stable 2D MOF as Dual Sensor for the Ultra-Sensitive Aqueous Phase Detection of Nitrofuran Antibiotics and Organochlorine Pesticides.

Misuse of antibiotics and pesticides has led to hazardous effects on human health, livestock, agriculture, and aquaculture, which urges researchers to find simple, rapid, efficient, and cost-effective methods for quick on-site analysis of these organic pollutants with functional materials. Herein, a 2D chemically robust MOF: IITKGP-71, {[Cd(MBPz)(2,6-NDC)]·2H2O}n is strategically developed with ease in scalability and exploited as dual sensors toward the toxic antibiotic and pesticide detection via luminescence quenching in aqueous medium. The framework displays exceptional chemical robustness in water for 3 months, in an open atmosphere over 2months, and wide range of aqueous pH solution (pH = 3-12) for a day. IITKGP-71 can selectively quench the nitrofuran antibiotics (NFZ and NFT) and organochlorine pesticide DCN while remaining unaffected by other interfering antibiotics and pesticides, respectively. An excellent trade-off between high effectivity (high Ksv) and high sensitivity (low LOD)was achieved for the targeted analytes. The easy scalability, high chemical stability, fast responsivity, multi-responsive nature, recyclability with outstanding structural stability made this framework viable in playing a crucial role in safeguarding aquatic ecosystems and public health from the hazardous effects of antibiotics and pesticides.

Unraveling the role of counter ions in shaping the structures of helical peptides in aqueous phase

AbstractHelical peptides, as well as proteins composed of helical peptides, play essential roles in various biological processes, including their functions as components of cell membranes and their interactions with biological membranes. Therefore, it is crucial to predict the propensity and structural characteristics of helices formed in solution or lipid environments for specific peptide sequences. Melittin and pexiganan are antimicrobial peptides (AMPs) that possess distinct sequence characteristics but exhibit similar structural properties in both solution and lipid environments. In this study, we conducted molecular dynamics simulations to investigate how the presence of counter ions creates differences in structural characteristics between these two peptides in solution. By analyzing the structures formed for each AMP using extended helical projections, we aimed to uncover the underlying principles governing the interaction between counter ions and peptide sequences, leading to the formation of stable structures. It was found that the coordination of counter ions effectively extends the helical surface and stabilizes the extended helix by reducing the electrostatic repulsion between charged residues. Our results demonstrate how sequence specificity influences helical structure formation in solution and provide an explanation for the varying degrees of synergistic effects exhibited by different helical AMPs.

Development and Evaluation of Lactose-Free Single-Unit and Multiple-Unit Preparations of a BCS Class II Drug, Rivaroxaban.

Background/Objectives: The aim of the present study was to develop lactose-free formulations of rivaroxaban, a novel oral anticoagulant used for the treatment and prevention of blood clotting. As a BCS Class II drug, rivaroxaban is characterized by poor solubility in aqueous media, posing a significant formulation challenge. Methods: To address this, phosphate-based excipients were employed to prepare both traditional single-unit dosage forms (tablets) and modern multiple-unit pellet systems (MUPS). These formulations were successfully developed and thoroughly evaluated for their physical properties and performance. Results: The resulting formulations demonstrated very good mechanical strength, including appropriate hardness and friability, alongside strong chemical stability. Their dissolution profiles met the requirements of the compendial monograph for Rivaroxaban Tablets and were comparable to those of the reference product, Xarelto® film-coated tablets. Conclusions: This study shows the potential for producing effective, stable, and patient-friendly medications that meet the needs of contemporary society, where an increasing number of individuals suffer from lactose intolerance or seek vegan-friendly alternatives.

One‐Step Maleimide‐Based Dual Functionalization of Protein N‐Termini

Maleimide derivatives are privileged reagents for chemically modifying proteins through the Michael addition reaction with cysteine due to their selectivity, operational simplicity, and commercial availability. However, since accessible free cysteine is rarely found in natural proteins, it is highly desirable to find alternative targets to enable direct bioconjugation of proteins with maleimides. In this study, we have developed an operationally simple and straightforward method for the N‐terminal modification of proteins without the need for mutagenesis via a copper(II)‐mediated [3+2] cycloaddition reaction with maleimides and 2‐pyridinecarboxaldehyde (2‐PCA) derivatives under non‐denaturing conditions at pH 6 and 37 °C in aqueous media. Our method utilizes commercially available maleimides to attach diverse functionalities to various N‐terminal amino acids. We demonstrate the preparation of a ternary protein complex cross‐linked at the N‐termini and dually modified trastuzumab equipped with monomethyl auristatin E (MMAE), a cytotoxic agent, and a Cy5 fluorophore (MMAE–Cy5–trastuzumab). MMAE–Cy5–trastuzumab retained human epidermal growth factor receptor 2 (HER2) recognition activity and exerted cytotoxicity against HER2‐positive cells. Furthermore, MMAE–Cy5–trastuzumab allowed successful visualization of HER2‐positive cancer cells in mouse tumors. This straightforward method will expand the accessibility of protein conjugates with well‐defined structures in a wide range of research fields.