Aqueous Solution Research Articles

Strong Anion Exchange On-Line Solid Phase Extraction and Liquid Chromatographic Determination of Cefuroxime in Spiked Human Plasma Samples

ABSTRACT On-line solid phase extraction and liquid chromatography (SPE-LC) allows direct determination of drugs from all biological fluids without any sample pre-treatment. Ion exchange is one of the SPE types used for the extraction of drug molecules, especially those containing carboxyl or amino groups. In this study, a novel sample pre-treatment free, fully automated on-line SPE-LC method was developed for the determination of cefuroxime, a broad-spectrum second-generation cephalosporin antibiotic, in spiked human plasma samples. A quaternary amine functionlized hydrophilic modified styrene polymer strong anion exchange (SAX) sorbent was utilized as the solid phase, which was in-house packed using a tailor-made SPE hardware. A C18 analytical column (150 × 4.6 mm, 5 μm) was connected to SPE by a 10-port switching valve. A mobile phase composed of acetonitrile and 10 mm aqueous ortho-phosphoric acid solution was used with a dual gradient elution (1.0 mL/min). Cefuroxime was detected at 276 nm. Total analysis time was 13 min including equilibration-fractionation-separation-washing steps. Linear range was 5.00–200.00 µg/mL. LOD and LOQ were 1.03 and 3.11 µg/mL, respectively. Developed on-line SPE-LC method was novel and practical with recovery values higher than 90% and RSDs ≤2.82%, indicating that the SAX sorbent was effective for the extraction of cefuroxime from spiked plasma samples.

Remove of a mixture cationics dyes in aqueous solution by a green emulsion liquid membrane

<p style="line-height:200%;margin-bottom:.0001pt;text-align:justify;"><span style="font-family:"Times New Roman","serif";font-size:12.0pt;line-height:200%;" lang="EN-US">The objective of this work is the treatment and purification of an aqueous solution loaded with a mixture of dyes, malachite green (MG) and rhodamine B (Rh-B) using a green emulsified membrane GELM. The proposed GELM process consists of a surfactant (Span 80), an internal phase (sulfuric acid) and a diluent (soybean oil). A Box-Behnken design was implemented to optimize the operating parameters. Three factors were varied: the mass percentage of Span 80, the concentration of the internal phase and a volume ratio V<sub>ext</sub>/V<sub>em</sub>, while keeping the other parameters constant. </span></p><p style="line-height:200%;margin-bottom:.0001pt;text-align:justify;"><span style="font-family:"Times New Roman","serif";font-size:12.0pt;line-height:200%;" lang="EN-US">The results of the optimization give an extraction yield of the dye mixture of 99.77% under the following optimum conditions: </span></p><p style="line-height:200%;margin-bottom:.0001pt;text-align:justify;"><span style="font-family:"Times New Roman","serif";font-size:12.0pt;line-height:200%;" lang="EN-US">10% by mass for Span 80, a concentration of 0.5 M for the internal phase and a V<sub>ext</sub>/V<sub>em</sub> volume ratio of 7.</span></p>

Facile synthesis of XGX-based hydrogel and its application for the removal of heavy metal ions from aqueous solutions

Facile synthesis of XGX-based hydrogel and its application for the removal of heavy metal ions from aqueous solutions

Characterization of Moroccan Raw and Modified Clay and Its Application in Removal of Methyl Orange Dye

ABSTRACTIn this work, we study the characterization of raw clay extracted from Jbel Lahbib Region of Tetouan in the north of Morocco, and organo‐modified clay by a cationic surfactant hexadecyltrimethylammonium bromide (CJL + HDTMA). In addition, we evaluate their potential to remove organic pollutants (methyl orange, MO) in aqueous solutions by means of the absorption techniques. All samples were characterized by XRD, FTIR, SEM‐EDAX, TGA, BET, and zeta potential. The XRD results show that the principal peak d001 moved from to Åfor the modified clay, the specific surface area of the raw and modified clay is 68.28 and 1.47 m2/g, respectively. Furthermore, these results confirm the success of this modification. With raw clay extracted from Jbel Lehbib (CJL), the maximum adsorption capacity of MO is pH‐dependent. Consequently, the MO adsorption is favored in the high acidic pH range. The adsorption kinetics of MO on both clays revealed that the equilibrium is rapidly obtained. Moreover, it is shown that the experimental data for MO adsorption on the two materials best fit the pseudo‐second‐order kinetic model. The adsorption isotherms indicate that the Sips and Temkin models correctly describe the adsorption of MO on the raw with experimental maximum adsorption value of 40.9 and 66.65 mg/g for raw and modified (CJL), respectively. The energy obtained from D‐R model (6.9 KJ/mol for raw clay and 12.86 KJ/mol for modified clay) suggested that process is dominated by physisorption for raw clay and chemisorption for modified clay. Besides, the thermodynamic study revealed that MO adsorption by crude clay is exothermic ( KJ/mol), physical, and spontaneous.

Ex Vivo, In Vitro and In Vivo Bone Health Properties of Grana Padano Cheese

Grana Padano (GP) is an Italian hard cooked cheese characterized by a long ripening process and high protein and Ca contents. After in vitro static simulated gastrointestinal digestion, GP digest contained caseinophosphopeptides that were 6 to 24 amino acids in length, including tri-phosphorylated species incorporating the pSer-pSer-pSer-Glu-Glu cluster. Using rat ileum tissue, the digest was used to assess Ca absorption ex vivo, which showed significantly better results for the GP digest in comparison to the CaCO3 aqueous solution. An in vitro intestinal model based on Caco-2/HT-29 cell co-culture was able to mimic Ca absorption from GP digest, with Ca-rich water as a control. The metabolite-containing medium was then used to treat osteoblast-like SaOS-2 cells. As a consequence, metabolized GP digest significantly increased the number of osteoblasts, whereas the metabolized water did not exert this effect. Finally, the mice were fed diets containing GP or CaCO3 and pea isolate and the in vivo outcomes were assessed through fluorescent probe and computed tomography. Mice fed a diet containing GP showed a higher increase in bone remodeling and volume in comparison to those fed a control diet containing CaCO3 and pea isolate. Overall, the ex vivo, in vitro and in vivo experiments highlighted the effectiveness of GP in improving Ca absorption, osteoblast proliferation and bone remodeling and volume.

Extraction of some heavy metal ions from aqueous solutions with new eco-friendly solvents

ABSTRACT In this work, the use of green ethanolic and hexanolic extractants (GEE, GHE) as extractant agents has been investigated in a variety of solvent extraction methods for iron, copper, manganese and zinc from aqueous solution. The impact of several parameters, including diluent type, pH, GEE, GHE extractant concentration, A/Oratio and temperature of extraction process were investigated. The thermodynamic parameters, including ΔH°, ΔG° and ΔS° were evaluated. The extraction of metal ions by GEE and GHE is an exothermic process from the negative value of enthalpy change (ΔH°). The extraction efficiencies of 10% (v/v) GEE for Fe, Mn, Cu and Zn were determined to be 92%, 87%, 77% and 72%, while the extraction efficiencies of 10% (v/v) GHE for Fe, Mn, Cu and Zn were determined to be 88%, 86%, 84% and 87%, respectively. The loaded Fe, Mn, Cu and Zn, can be stripped using 1 M H2SO4 as inorganic acid. The maximum stripping efficiency for removal of loaded metals ions on GEE and GHE were studied.

Assembly-enhanced recognition: A biomimetic pathway to achieve ultrahigh affinities

On the one hand, nature utilizes hierarchical assemblies to create complex biological binding pockets, enabling ultrastrong recognition toward substrates in aqueous solutions. On the other hand, chemists have been fervently pursuing high-affinity recognition by constructing covalently well-preorganized stereoelectronic cavities. The potential of noncovalent assembly, however, for enhancing molecular recognition has long been underestimated. Inspired by (strept)avidin, an amphiphilic azocalix[4]arene derivative capable of assembly in aqueous solutions has been explored by us and demonstrated to exhibit ultrahigh binding affinity (up to 10 12 M −1 ), which is almost four orders of magnitude higher than those reported for nonassembled azocalix[4]arenes. An ultrastable azocalix[4]arene/photosensitizer complex has been applied in hypoxia-targeted photodynamic therapy for tumors. These findings highlight the immense potential of an assembly-enhanced recognition strategy in the development of the next generation of artificial receptors with appropriate functionalities and extraordinary recognition properties.

Nano-Fibrillated Bacterial Cellulose Nanofiber Surface Modification with EDTA for the Effective Removal of Heavy Metal Ions in Aqueous Solutions

Nano-fibrillated bacterial cellulose (NFBC) has very long fibers (>17 μm) with diameters of approximately 20 nm. Hence, they have a very high aspect ratio and surface area. The high specific surface area of NFBC can potentially be utilized as an adsorbent. However, NFBC has no functional groups that can bind metal ions, limiting its potential applications. In this study, the hydroxyl groups on the surface of NFBC were chemically modified with EDTA monoanhydride to convert NFBC into a metal adsorbent. The fiber morphology and crystal structures of the modified NFBC were almost identical to those of the unmodified NFBC, suggesting that the surface hydroxyl groups of NFBC were well-conjugated with the EDTA groups. Surface-modified NFBC preferentially adsorbed transition metals in aqueous solutions, such as Cu(II), Hg(II), Pb(II), and Cd(II), but hardly adsorbed Mg(II) and Cr(VI). The adsorption of heavy metal ions can be explained by the pseudo-second-order kinetics of the chemisorption process and the Langmuir isotherm model. Furthermore, the EDTA-modified NFBC is a renewable and recyclable adsorbent. The results of this study indicate that surface-modified NFBC can be utilized as a biosorbent for heavy metal removal in chemical, food, pharmaceutical, and other industrial fields.

Carbon nanotube/bentonite @ polyvinylidene fluoride tri-flouro ethylene nanocomposite matrix for surpior elimination of carcinogenic dye from wastewater

Abstract This study examines the sorption behavior of Congo Red (CR) dye from water-based solutions using a synergistic nanocomposite made of Bentonite (BT), multi-walled carbon nanotubes (MWCNTs), and a Poly (vinylidene fluoride tri-flouroethylene) (P(VDF-TRFE)) polymer matrix with exceptional adsorption capacity for the selective removal of Congo red dye from aqueous solutions. This is done in order to address the urgent concerns surrounding the health and environmental implications of CR dye. Utilizing modern analytical technique such as FTIR, XRD, SEM, TEM, and TGA, the adsorption physicochemical interaction and nanocomposite manufacturing were carefully investigated, offering thorough insights into the composite's general properties. Nanocomposite structures of between 31 and 37 nm in diameter were discovered by TEM examination. The adsorption process was pH dependent, reaching a peak removal effectiveness of 94.5% at pH 3.0. The correlation coefficients obtained from kinetic modeling using pseudo-first-order and pseudo-second-order equations were 0.97389 and 0.96802, respectively, suggesting that the adsorption mechanism adhered to first-order rate kinetics. Thermodynamic investigation revealed an exothermic and spontaneous reaction, with a negative ΔG value between − 7.45 and − 7.95 J/mol. The nanocomposite outperformed the capacities reported for individual components in earlier investigations, with an impressive monolayer sorption capacity (qmax) of 143.88 mg/g. As a result, there is great potential for this innovative nanocomposite to be a very successful adsorbent for treating industrial wastewater. Graphical Abstract

Optimization Study of Ammonium Adsorption from Aqueous Solution on Carbon Black Modified with Sodium Dodecylbenzene Sulfonate: Kinetics, Isotherms, and Thermodynamics

Optimization Study of Ammonium Adsorption from Aqueous Solution on Carbon Black Modified with Sodium Dodecylbenzene Sulfonate: Kinetics, Isotherms, and Thermodynamics

Investigating the Restricted Dynamical Environment in and Around Aβ Peptide Oligomers in Aqueous Ionic Liquid Solutions.

It is widely believed that the aggregation of amyloid β (Aβ) peptides into soluble oligomers is the root cause behind Alzheimer's disease. In this study, we have performed room-temperature molecular dynamics (MD) simulations of aggregated Aβ oligomers of different sizes (pentamer (O(5)), decamer (O(10)), and hexadecamer (O(16))) in binary aqueous solutions containing 1-butyl-3-methylimidazolium tetrafluoroborate ([BMIM][BF4]) ionic liquid (IL). Investigations have been carried out to obtain a microscopic understanding of the effects of the IL on the dynamic environment around the exterior surfaces and within the confined nanocores of the oligomers. The calculations revealed that in contrast to nearly uniform dynamics near the exterior surface, heterogeneous structural distortions of oligomers of varying sizes and nonuniform distributions of water and IL components within their core volumes modify the core dynamics in a differential manner. It is demonstrated that increasingly restricted mobility of water and IL components is the origin behind the longer time scale of dynamic heterogeneity in and around the oligomers. Importantly, due to the equivalent nondirectional nature of the B-F bonds, BF4- anions are found to reorient on a time scale faster than that of water molecules. Further, the structural relaxation of protein-anion (PA) hydrogen bonds around the oligomers has been found to be correlated with sluggish translational motions of the anions but anticorrelated with their reorientational time scale. In addition, it is quantified that compared to the pure aqueous medium, strengthening of protein-water (PW) hydrogen bonds in the presence of the IL leads to their longer lifetimes.

Exploring and analyzing the causes of color in the earth

Color is an essential element of human visual perception, which exists in all aspects of our daily lives and plays a key role in scientific research and technological applications. Color is produced by various mechanisms, including absorption and reflection of chemical pigments, complex formation of transition metal ions, and micro- and nanostructural modulation of structural colors. This paper aims to comprehensively explore the scientific principles of color generation and its applications in different fields. The article first describes how transition metal ions exhibit colors by forming complexes and explains in detail the coordination process of copper ions in an aqueous solution and its resulting d-orbital splitting, which in turn absorbs light of specific wavelengths and exhibits complementary colors. Secondly, the article explores the mechanism of color expression of natural pigments in plants, significantly how pigment molecules containing conjugated double bonds, such as -carotene, can absorb specific wavelengths of light and exhibit vivid colors through electron delocalization and energy level jumps. Finally, the article illustrates the principles of structural color and its potential for industrial applications, including using micro- and nanostructures, such as photonic crystals, to modulate the scattering and absorption of light, thus enabling dynamic changes in color and environmental protection. The in-depth exploration of the mechanism of color generation enhances our understanding of the basic principles of color science. It provides theoretical support for technological innovation and practical applications in related fields.

Supramolecular Gelation Based on Native Amino Acid Tyrosine and Its Charge-Transfer Complex Formation.

Self-assembly of amino acids and short-peptide derivatives attracted significant curiosity worldwide due to their unique self-assembly process and wide variety of applications. Amino acid is considered one of the important synthons in supramolecular chemistry. Self-assembly processes and applications of unfunctionalized native amino acids have been less reported in the literature. In this article, we are first-time reporting the self-assembly process of tyrosine (Tyr), an aromatic amino acid, in dimethyl sulfoxide (DMSO) solvent. Most of the studies related to Tyr self-assembly were reported in different aqueous solutions. In our work, we studied the self-assembly in several common organic solvents and found that Tyr could self-assemble into a supramolecular gel in dimethyl sulfoxide (DMSO) solvent. The self-assembly process was investigated by several techniques, such as UV-vis, fluorescence, FTIR, and NMR spectroscopy. Morphological features on the nanoscale were investigated through scanning electron microscopy (SEM). SEM images indicated the formation of nanofibrils with high aspect ratios. The supramolecular gel property was investigated by different rheological experiments. Computational study on the self-assembly process of Tyr in DMSO medium suggested that noncovalent interactions like hydrogen bonding and π-π stacking among the Tyr molecules played a prominent role. Finally, the charge-transfer complex formation ability of electron-rich Tyr with electron-deficient 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) was studied. In the presence of DDQ due to the charge-transfer complex formation, the supramolecular gel converted into a reddish color solution, and their fibrillar nanoscale morphologies collapsed.

Measurement of capillarity using oblique plates as a function of the separation angle, temperature and glycerol concentration in water

Abstract Capillarity refers to the ability of a liquid to move within narrow spaces such as tubes and pores with reduced diameters or between two oblique plates with a very small angle between them. It is well known that the height a liquid can reach due to capillarity is directly related to the values of the surface tension, the density, and the contact angle. In this investigation, a study is conducted on the dependence of these properties on the glycerol concentration in an aqueous solution and on the water temperature. The experimental device used is a capillary formed by two oblique glass plates, which allows for the direct observation of the liquid height variation as a function of the separation angle between the plates. This phenomenon is studied using Jurin's law, widely used in the study of capillarity. The results are explained using the Connors-Wright surface tension model and the Eötvös rule. The experiment is very low cost and easy to implement in undergraduate science laboratories, making it useful for exploring the capillarity phenomenon of liquids.

Dilute Povidone-Iodine Irrigation: The Science of Molecular Iodine (I2) Kinetics and Its Antimicrobial Activity.

Dilute povidone-iodine (polyvinylpyrrolidone iodine [PVP-I]) irrigation in spine surgery and total joint arthroplasty has seen a rapid and substantial increase in its use during the past decade. Yet, most surgeons do not know the chemistry and biochemistry that explain its efficacy in preventing infections. PVP-I forms a complex with molecular iodine (I2), facilitating the delivery of I2 to the membrane of the infectious organism. Here, PVP-I establishes an equilibrium between complexed and noncomplexed (free) I2 in the aqueous solution. The I2 acts at numerous cellular targets of infecting organisms augmenting its role as a biocidal molecule. The paradoxical increase in the concentration of I2 that occurs with dilution of PVP-I is a result of equilibrium kinetics and is associated with an enhanced antimicrobial activity. Cytotoxicity studies have yielded conflicting results, but most endorse diluted concentrations as being less damaging to tissues. Clinical studies have verified notable reductions in surgical site infections with a 3-minute soak of 0.35% dilute povidone-iodine irrigation. Guidelines from the World Health Organization, Centers for Disease Control and Prevention, and International Consensus Meeting on Musculoskeletal Infection support the use of prophylactic incisional wound irrigation with aqueous PVP-I to reduce and prevent surgical site infections.

Hydrogenolysis of Glucose in Aqueous Solution into Propylene Glycol on Copper-Containing Catalysts

Hydrogenolysis of Glucose in Aqueous Solution into Propylene Glycol on Copper-Containing Catalysts

Synthesis of Arsenocholine-Type Polycation Brush and Its Hydration Structure in Aqueous Solution

Synthesis of Arsenocholine-Type Polycation Brush and Its Hydration Structure in Aqueous Solution

Transport Numbers and Electroosmosis in Cation-Exchange Membranes with Aqueous Electrolyte Solutions of HCl, LiCl, NaCl, KCl, MgCl2, CaCl2 and NH4Cl

Electroosmosis reduces the available energy from ion transport arising due to concentration gradients across ion-exchange membranes. This work builds on previous efforts to describe the electroosmosis, the permselectivity and the apparent transport number of a membrane, and we show new measurements of concentration cells with the Selemion CMVN cation-exchange membrane and single-salt solutions of HCl, LiCl, NaCl, MgCl2, CaCl2 and NH4Cl. Ionic transport numbers and electroosmotic water transport relative to the membrane are efficiently obtained from a relatively new permselectivity analysis method. We find that the membrane can be described as perfectly selective towards the migration of the cation, and that Cl− does not contribute to the net electric current. For the investigated salts, we obtained water transference coefficients, tw, of 1.1± 0.8 for HCl, 9.2 ± 0.8 for LiCl, 4.9 ± 0.2 for NaCl, 3.7 ± 0.4 for KCl, 8.5 ± 0.5 for MgCl2, 6.2 ± 0.6 for CaCl2 and 3.8 ± 0.5 for NH4Cl. However, as the test compartment concentrations of LiCl, MgCl2 and CaCl2 increased past 3.5, 1.3 and 1.4 mol kg−1, respectively, the water transference coefficients appeared to decrease. The presented methods are generally useful for characterising concentration polarisation phenomena in electrochemistry, and may aid in the design of more efficient electrochemical cells.

Treatment of excessive growth of granulation tissue in horses by topical application of resveratrol

AbstractExcessive growth of granulation tissue (EGT) is a common complication during wound healing in horses. Wounds involving lower limbs are especially prone to the development of EGT. Often increased expression of transforming growth factor‐β (TGF‐β) is found in the EGT. In the present report, resveratrol was used as TGF‐β modifier. Topical application of an aqueous solution of resveratrol at 0.01 mg/mL once daily for 5‒7 weeks depending on EGT size, successfully suppressed the EGT growth in all seven horses in the present case report.

Indocyanine green dyed gauze-guided minimum invasive surgery for anatomical landmarks and preventing gauze remnants: a pilot study.

We aimed to develop a novel fluorescent surgical gauze dyed with indocyanine green (ICG) to guide surgeons to the target anatomical destination during surgery for real-time navigation and to prevent gauze remnants after surgery. Surgical gauze was dyed with an aqueous solution of ICG (5.0 × 10- 5 mol L- 1 for Steraze, 1.5 × 10- 4 mol L- 1 for BK-Opeze) at 132°C (inside pressure: 2.82atm, 286kPa) for 15min using an autoclave, followed by washing with distilled water, drying at room temperature, and sterilizing at 132°C for 8min before surgery. Fluorescence (FL) intensity was examined preclinically in the resected specimens using the SPY PHI (Stryker) system. Fourteen patients who underwent laparoscopic- and robotic-assisted gastroenterological surgery at Showa University Hospital were included. Fluorescent emission of ICG-dyed gauze was clearly observed through resected specimens with a thickness of approximately 10mm or more. In a clinical trial, the ICG-dyed gauze was detected earlier with near-infrared (near-IR) FL imaging than under white light during seven cases of laparoscopic and robotic surgery, which could become a precise marker for surgeons to locate the dissection site despite overlaying tissues and nearby disturbances. Additionally, no seepage of ICG from the gauze was observed in all surgical fields. We successfully developed ICG-dyed gauze exhibiting bright near-IR FL which can guide surgeons to the target anatomical destination and prevent gauze remnants during surgery. This invention would be a powerful support for real-time navigation surgery.