Aqueous Environment Research Articles

Gamma rays impact on 2D-MoS2 in water solution.

Two-dimensional transition metal dichalcogenides, particularly MoS2, are interesting materials for many applications in aerospace research, radiation therapy and bioscience more in general. Since in many of these applications MoS2-based nanomaterials can be placed in an aqueous environment while exposed to ionizing radiation, both experimental and theoretical studies of their behaviour under these conditions is particularly interesting. Here, we study the effects of tiny imparted doses of 511keV photons to MoS2 nanoflakes in water solution. To the best of our knowledge, this is the first study in which ionizing radiation on 2D-MoS2 occurs in water. Interestingly, we find that, in addition to the direct interaction between high-energy photons and nanoflakes, reactive chemical species, generated by γ-photons induced radiolysis of water, come into play a relevant role. A radiation transport Monte Carlo simulation allowed determining the elements driving the morphological and spectroscopical changes of 2D-MoS2, experimentally monitored by SEM microscopy, DLS, Raman and UV-vis spectroscopy, AFM, and X-ray photoelectron techniques. Our study demonstrates that radiolysis products affect the Molybdenum oxidation state, which is massively changed from the stable + 4 and + 6 states into the rarer and more unstable + 5. These findings will be relevant for radiation-based therapies and diagnostics in patients that are assuming drugs or contrast agents containing 2D-MoS2 and for aerospace biomedical applications of 2DMs investigating their actions into living organisms on space station or satellites.

Near-infrared light enhanced oxygen vacancies on metal organic frameworks through photothermal effect for peroxydisulfate activation to remove organic pollutants

Peroxydisulfate (PDS)-based advanced oxidation processes (AOPs) are a promising strategy for addressing the challenges of contamination in aqueous environment. Taking advantage of solar energy based photocatalysis showed great potential on PDS activation for pollution control. However, the limited usage of near-infrared (NIR) region by photocatalysts restricted the realization of using full sunlight energy. Herein, zeolitic imidazolate frameworks derived materials (ZNC) with oxygen vacancies (VO) are designed and obtained, which can efficiently activate PDS under NIR light due to the photothermal effect, exhibiting superior carbamazepine (CBZ) degradation performance (84 % of CBZ within 60 min). Further quenching tests and electron paramagnetic resonance detection demonstrate that the photothermal effect can enhance the concentration of oxygen vacancies on the surface and facilitate charge separation of ZNC, which effectively activate PDS to generate O2−, 1O2, and h+, thus significantly enhancing the photocatalytic degradation of CBZ. Additionally, combining the results of intermediates analysis and DFT calculation, a systematic CBZ degradation pathway by two tracks is proposed. Moreover, the overall potential risks of CBZ are expected to be weakened in the ZNC/PDS/NIR process through photothermal catalytic degradation. Thus, a new strategy is provided for optimizing the use of solar energy to boost PDS activation for water purification.

The hierarchical structure of organic mixed ionic-electronic conductors and its evolution in water.

Polymeric organic mixed ionic-electronic conductors underpin several technologies in which their electrochemical properties are desirable. These properties, however, depend on the microstructure that develops in their aqueous operational environment. We investigated the structure of a model organic mixed ionic-electronic conductor across multiple length scales using cryogenic four-dimensional scanning transmission electron microscopy in both its dry and hydrated states. Four-dimensional scanning transmission electron microscopy allows us to identify the prevalent defects in the polymer crystalline regions and to analyse the liquid crystalline nature of the polymer. The orientation maps of the dry and hydrated polymers show that swelling-induced disorder is mostly localized in discrete regions, thereby largely preserving the liquid crystalline order. Therefore, the liquid crystalline mesostructure makes electronic transport robust to electrolyte ingress. This study demonstrates that cryogenic four-dimensional scanning transmission electron microscopy provides multiscale structural insights into complex, hierarchical structures such as polymeric organic mixed ionic-electronic conductors, even in their hydrated operating state.

Discovery of Multiple Light-Harvesting States of the Photosynthetic Protein PE545.

Cryptophytes are photosynthetic microalga that flourish in a remarkable diversity of natural environments by using pigment-containing proteins with absorption maxima tuned to each ecological niche. While this diversity in the absorption has been well established, the subsequent photophysics is highly sensitive to the local protein environment and so may exhibit similar variation. Thermal fluctuations of the protein conformation are expected to introduce photophysical heterogeneity of the pigments that may have evolved important functional properties in a manner similar to that of the absorption. However, such heterogeneity is averaged out in ensemble measurements and, therefore, has not yet been probed. Here, we report single-molecule measurements of phycoerythrin 545 (PE545), the prototypical cryptophyte antenna protein, in its native dimeric form. A conformational ensemble was resolved consisting of distinct photophysical states with different light-harvesting properties. Proteins that did not quench, partially quenched, or fully quenched absorbed light were observed. Light intensity increased the quenched-state population of the dimer, potentially as a mechanism to deal with the extreme light intensities found in aqueous environments. Cross-linking, which mimics local interactions, introduces this light-dependent functionality while also suppressing other conformational dynamics. The cellular organization can, therefore, actively modulate the protein conformation and dynamics, selecting for distinct levels of light harvesting. Thus, the complex conformational equilibrium provides an additional mechanism for cryptophytes and likely other photosynthetic organisms to optimize solar energy capture and conversion.

Alkoxy-functionalized covalent organic Framework membranes for efficient molecular sieving with high water permeance

The presence of various trace water-soluble organic pollutants, such as dyes, poses significant potential risks to human health and ecosystems. Membrane technology presents a promising and sustainable approach for their removal from aqueous environments. However, the amorphous structure of most commercial membranes makes it challenging to achieve effective separation with high water flux. Here, we present a novel series of hydrophilic COF membranes with different alkoxy sidechain lengths for the first time. These alkoxy sidechain functional COF membranes exhibit efficient rejection of water-soluble organic dyes, including rose bengal (> 50 %), congo red (> 98 %), brilliant blue R250 (> 99 %), and alcian blue (> 99 %). Moreover, these membranes demonstrate a high water flux exceeding 291.8 L m-2h−1 bar−1 and exceptional long-term operational stability lasting at least 2880 min. The superior performance of COF membranes is attributed to their optimal pore size, excellent hydrophilicity, and high crystallinity. This finding offers a promising approach for effectively eliminating water-soluble organic pollutants, thereby ensuring the safety and sustainability of the water supply.

Compact Electron Paramagnetic Resonance on a Chip Spectrometer Using a Single Sided Permanent Magnet.

Electron paramagnetic resonance (EPR) spectroscopy provides information about the physical and chemical properties of materials by detecting paramagnetic states. Conventional EPR measurements are performed in high Q resonator using large electromagnets which limits the available space for operando experiments. Here we present a solution toward a portable EPR sensor based on the combination of the EPR-on-a-Chip (EPRoC) and a single-sided permanent magnet. This device can be placed directly into the sample environment (i.e., catalytic reaction vessels, ultrahigh vacuum deposition chambers, aqueous environments, etc.) to conduct in situ and operando measurements. The EPRoC reported herein is comprised of an array of 14 voltage-controlled oscillator (VCO) coils oscillating at 7 GHz. By using a single grain of crystalline BDPA, EPR measurements at different positions of the magnet with respect to the VCO array were performed. It was possible to create a 2D spatial map of a 1.5 mm × 5 mm region of the magnetic field with 50 μm resolution. This allowed for the determination of the magnetic field intensity and homogeneity, which are found to be 254.69 mT and 700 ppm, respectively. The magnetic field was mapped also along the vertical direction using a thin film a-Si layer. The EPRoC and permanent magnet were combined to form a miniaturized EPR spectrometer to perform experiments on tempol (4-hydroxy-2,2,6,6-teramethylpiperidin-1-oxyl) dissolved in an 80% glycerol and 20% water solution. It was possible to determine the molecular tumbling correlation time and to establish a calibration procedure to quantify the number of spins within the sample.

Ion specificity on cysteine tripeptides in aqueous environments revealed by molecular simulation

Molecular dynamics simulations were conducted to investigate the interactions of cysteine tripeptides with ions and water molecules in solutions of salts (MA, M = Li+ and Cs+, A = halide ions). The results revealed that as the anion size increases, cations aggregate more easily around the tripeptide, irrespective of capping. Radial distribution function (RDF) analysis showed direct interactions between F− and tricysteine, whereas Cl−, Br−, and I− exhibited indirect binding. Comparison between Li+ and Cs+ systems indicated that the smaller Li+ ions tend to distribute more around the tripeptide, engaging in direct interactions, whereas Cs+ ions interact indirectly, mediated by water molecules. Interaction energy analysis demonstrated that in lithium salt solutions, the total energy of anions with tricysteine decreased with anion size for both capped and uncapped systems. In cesium salt solutions, the anionic I− had the strongest interaction with cysteine tripeptides, and the cationic Cs+ interaction with tripeptides peaked in the CsI solution. The results highlight differences in ionic interactions depending on the anion-cation correlations of different salts.

Carob pulp flour as an innovative source of bioactive molecules for the preparation of high-value-added jellies

The rising demand for healthier alternatives to traditional sugary products has driven the exploration of natural substitutes for sucrose. This study aimed to investigate carob pulp flour (CPF) as a viable alternative to sucrose in the production of high-value jellies with enhanced health benefits. Carob pulp flour was spectroscopically characterized, revealing the presence of bioactive molecules, such as natural antidiabetic polyols and polyphenols. Colorimetric tests demonstrated a significant concentration of polyphenolic molecules in CPF, with a remarkable scavenging activity against radical species in both organic and aqueous environments. Jellies based on CPF (CGC) were successfully prepared and exhibited strong antioxidant activity against ABTS (IC50 0.158 mg mL−1) and DPPH (IC50 0.175 mg mL−1) radicals, maintaining their properties over 15 days, unlike the sucrose-based control, which showed no antioxidant activity. The CPF-enhanced jellies consistently demonstrated higher G′ values (in the range 20–35 °C) than the sucrose-based jellies, indicating improved consistency, elasticity, and strong gel properties, even at higher temperatures. Sensory analysis revealed significant differences, with CPF-based jellies displaying enhanced chocolate (2.3 ± 1.0), ripe fruit (2.3 ± 1.8), and caramel odors (2.0 ± 0.9), as well as increased bitterness and astringency, reduced sweetness, and improved texture. Additionally, CPF-based jellies exhibited significant hypoglycemic properties, with dose-dependent inhibitory effects on α-amylase (57.7 %) and α-glucosidase (50.3 %), and a moderate lipase inhibitory effect (48.6 %) at the maximum concentrations tested. The findings of this study highlight the potential of CPF as a functional ingredient in the food industry, offering a healthier alternative to sucrose in jelly production. The inclusion of CPF not only enhances the antioxidant and sensory properties of jellies but also contributes to significant hypoglycemic effects, making it a promising candidate for the development of functional foods with added health benefits.

Advances in Chitosan-Based Materials for Application in Catalysis and Adsorption of Emerging Contaminants

The increasing disposal of emerging contaminants in the environment is a worldwide concern due to environmental impacts, such as toxicity, hormonal disorders, and bioaccumulation. The persistence of these pollutants in water bodies makes conventional pollutant removal techniques inefficient or partial, thus requiring the development of new, more effective, sustainable remediation technologies. Therefore, chitosan-based materials have emerged as a promising alternative for application in catalysis and contaminant removal. The biopolymer has functional properties that make it an excellent adsorbent capable of removing more specific pollutants, such as pharmaceuticals, microplastics, agricultural pesticides, and perfluoroalkyl and poly-fluoroalkyl substances, which are increasingly in evidence today. Therefore, this review of recent and advanced research into using chitosan to manufacture catalytic and adsorption materials offers an innovative approach to treating contaminants in aqueous environments, significantly reducing their presence and impact. It discusses the advantages of using chitosan as an adsorbent and catalyst and its role as a support for catalysts and biocatalysts. In addition, the review highlights the diversity of the physical forms of chitosan, such as particles, membranes, and hydrogels, and its possible chemical modifications, highlighting its effectiveness in catalytic applications and the removal of a wide range of emerging contaminants.

Green synthesis of magnesium oxide nanoparticles using extracts of two brown seaweeds for removal of acid black 1 dye from aqueous environments

Water pollution by synthetic dyes, particularly acid black 1, poses a significant environmental challenge. The present study has addressed this issue by synthesizing novel magnesium oxide (MgO) nanocomposites using extracts from Padina sanctae crucis (Psc) and Sargassum hystrix (Sh) algae via a sol-gel process. The primary objective was to evaluate the efficacy of these nanocomposites in removing acid black 1 dye from aqueous solutions. The synthesized materials were characterized using Fourier transform infrared spectroscopy (FT-IR), energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) analysis, thermal gravimetric analysis (TGA), and dynamic light scattering (DLS). The results show the successful synthesis of MgONPs and MgO@Sh and MgO@Psc NPs with approximate sizes of 45.64–65.64, 52.14–59.09 and 39.19–58.30 nm. Batch mode experiments were conducted to assess the influence of contact time, pH, and adsorbent dosage on dye removal efficiency. The results demonstrated that at pH 6, increasing the adsorbent dosage from 0.5 to 2 g/L enhanced the dye removal efficiency from 41.6% to 59.1% for MgO@Psc and from 43.4% to 64.1% for MgO@Sh. The Sips isotherm model and intra-particle diffusion kinetic model provided the best fit to the experimental data. The negative values of ΔG° indicated, which the adsorption process is more spontaneous at higher temperatures. This study highlights the potential of MgO@Psc and MgO@Sh nanocomposites as effective adsorbents for acid black 1 removal, offering a promising solution for water purification.

Structural basis for the access and binding of resolvin D1 (RvD1) to formyl peptide receptor 2 (FPR2/ALX), a class A GPCR.

Inflammation is essential to the body's defense against tissue injury and microbial invasion. However, uncontrolled inflammation is highly detrimental and can result in chronic inflammatory diseases such as asthma, cancer, obesity, and diabetes. An increasing body of evidence suggests that specialized pro-resolving lipid mediators (SPMs), such as resolvins, are actively involved in critical cellular events that drive the resolution of inflammation and a return to homeostasis. An imbalance caused by insufficient SPMs can result in the unsuccessful resolution of inflammation. The D-series resolvins (metabolites of docosahexaenoic acid), such as resolvin D1 (RvD1) and resolvin D2 (RvD2), carry out their pro-resolving functions by directly binding to class A G protein-coupled receptors FPR2/ALXR and GPR32, and GPR18, respectively. We recently demonstrated that RvD1 and RvD2 preferentially partition and accumulate at the polar headgroup regions of the membrane. However, the mechanistic detail of how RvD1 gains access to the FPR2 binding site from a surrounding membrane environment remains unknown. In this study, we used classical MD and well-tempered metadynamics simulations to examine the structural basis for the access and binding of RvD1 to its target receptor from aqueous and membrane environments. The results offer valuable insights into the access path, potential binding pose, and key residue interactions essential for the access and binding of RvD1 to FPR2/ALXR and may help in identifying small molecule therapeutics as a possible treatment for inflammatory disorders.

Hydrogen Bond Network Shaping Proton Penetration Behavior across Two-Dimensional Nanoporous Materials.

In this study, we investigate aqueous proton penetration behavior across four types of two-dimensional (2D) nanoporous materials with similar pore sizes using extensive ReaxFF molecular dynamics simulations. The results reveal significant differences in proton penetration energy barriers among the four kinds of 2D materials, despite their comparable pore sizes. Our analysis indicates that these variations in energy barriers stem from differences in the hydrogen bond (HB) network formed between the 2D nanoporous materials and the aqueous environment. The HB network can be classified into two categories: those formed between the surface of the 2D nanoporous materials and the aqueous environment, and those formed between the edge atoms of the nanopores and the water molecules inside the pores. A strong HB network formed between the surface of the 2D nanoporous materials and the aqueous environment induces an orientational preference of water molecules, resulting in an aggregated water layer with high density. This high-density water region traps protons, making it difficult for them to escape and penetrate the nanopores. On the other hand, a strong HB network formed between the edge atoms of the nanopores and the water molecules inside the pores impedes the rotation and migration of water molecules, further inhibiting proton penetration behavior. To facilitate the proton penetration process, in addition to a sufficiently large pore size, a weak HB network between the 2D nanoporous material and the aqueous environment is necessary.

Enhanced Alkene Oxidative Cleavage in Water via Photoexcited FeIV Species within Covalent Organic Framework Thin Films.

The oxidative cleavage of alkenes is a crucial step in synthesizing key organic molecules featuring carbonyl functional groups prevalent in natural products and pharmaceuticals. We introduce a photochemical method for heterogeneous C=C bond cleavage, employing photo-catalytically generated [(bTAML)FeIV-O-FeIV(bTAML)]- species (where bTAML stands for biuret-modified tetraamido macrocyclic ligand) in aqueous environments under gentle conditions. Leveraging the photosensitizing properties of Covalent Organic Frameworks (COFs) and their advantageous morphological traits as films, we enhance the reaction by closely associating the substrate with the catalyst. This study marks the inaugural demonstration of Fe2 IV-μ-oxo radical cation and FeIV=O species facilitating alkene cleavage in water against a backdrop of a hydrophobic COF. Through comprehensive mechanistic studies, including control experiments, we confirm that these two high-valent iron oxo species collaborate to cleave alkenes, forming an intermediate epoxide. Our approach yields moderate to high success across various alkenes, displaying diverse functional groups (achieving up to 75 % yield) with notable efficiency and selectivity towards aldehyde/ketone products. Moreover, the heterogeneous COF film, immobilizing (Et4N)2[FeIII(Cl)bTAML], exhibits exceptional recyclability, enduring up to four cycles.

Study of chlorine disinfection on the formation and resuscitation of Viable but nonculturable (VBNC) bacteria in drinking water distribution systems

The presence of Viable but nonculturable (VBNC) bacteria in drinking water distribution systems(DWDS)which can recover and regain pathogenicity under certain conditions, leads to a serious underestimation of the number of microorganisms in the water and consequently microbiological risks. This study investigated E. coli's biofilm integrity and metabolic activity post‑chlorine disinfection and during resuscitation in a Circulating-flow Dynamic biofilm Contactor (CDC) reactor. Chlorine rapidly induced the VBNC state, with concentrations ≥0.3 mg/L causing all respiratory-active bacteria to transition. Higher chlorine levels damaged cell biofilms, reducing intact cell counts by 95 % and depleting ATP. VBNC bacteria in biofilms quickly regained culturability, utilizing available nutrients and ATP. Within 1–4 days, culturable bacteria in the biofilm increased from 2.29 to 4.95 log CFU/mL, significantly faster than in water. This growth corresponded with rising ATP levels, though slower than in aqueous environments. Signaling molecules (C6, C8, C12, C14) regulated gene expression during resuscitation, aiding bacterial recovery and proliferation. Chlorine disinfection disrupted intercellular communication, altering VBNC bacteria's physiological and metabolic characteristics. These findings highlight the complex dynamics of VBNC bacteria in water systems, their resuscitation potential, and the importance of biofilms in bacterial recovery, emphasizing the need for comprehensive water treatment strategies.

Enhanced Alkene Oxidative Cleavage in Water via Photoexcited FeIV Species within Covalent Organic Framework Thin Films

AbstractThe oxidative cleavage of alkenes is a crucial step in synthesizing key organic molecules featuring carbonyl functional groups prevalent in natural products and pharmaceuticals. We introduce a photochemical method for heterogeneous C=C bond cleavage, employing photo‐catalytically generated [(bTAML)FeIV−O−FeIV(bTAML)]− species (where bTAML stands for biuret‐modified tetraamido macrocyclic ligand) in aqueous environments under gentle conditions. Leveraging the photosensitizing properties of Covalent Organic Frameworks (COFs) and their advantageous morphological traits as films, we enhance the reaction by closely associating the substrate with the catalyst. This study marks the inaugural demonstration of Fe2IV‐μ‐oxo radical cation and FeIV=O species facilitating alkene cleavage in water against a backdrop of a hydrophobic COF. Through comprehensive mechanistic studies, including control experiments, we confirm that these two high‐valent iron oxo species collaborate to cleave alkenes, forming an intermediate epoxide. Our approach yields moderate to high success across various alkenes, displaying diverse functional groups (achieving up to 75 % yield) with notable efficiency and selectivity towards aldehyde/ketone products. Moreover, the heterogeneous COF film, immobilizing (Et4N)2[FeIII(Cl)bTAML], exhibits exceptional recyclability, enduring up to four cycles.

Mechanism of biochar in alleviating the inhibition of anaerobic digestion under ciprofloxacin press

The antibiotic ciprofloxacin (CIP), detected in various aqueous environments, has broad-spectrum antimicrobial properties that can severely affect methanogenic performance in anaerobic systems. In this study, a novel strategy to alleviate the inhibition of AD performance under CIP press with the direct addition of biochar (BC) prepared from corn stover was proposed and the corresponding alleviation mechanism was investigated. When the dosage of BC was 5 and 20 g/L, the cumulative methane production in AD could reach 317.9 and 303.0 mL/g COD, and the CIP degradation efficiencies reached 94.1 % and 96.6 %, significantly higher than those of 123.0 mL/g COD and 81.2 % in the Control system. BC avoided excessive reactive oxygen species in anaerobic systems and induced severe oxidative stress response, while protecting the cell membrane and cell wall of microorganisms. Microorganisms could consume and utilize more organic extracellular polymeric substances for their growth and metabolism. When BC was involved in AD, fewer toxic intermediates were generated during CIP biodegradation, reducing acute and chronic toxicity in anaerobic systems. Microbial diversity suggested that BC could enrich functional microorganisms involved in direct interspecies electron transfer like Methanosaeta, norank_f_Bacteroidetes_vadinHA17, JGI-0000079-D21 and Syntrophomonas, thus facilitating the methanogenic process and CIP degradation. Genetic analyses showed that BC could effectively upregulate functional genes related to the conversion of butyrate-to-acetate and acetyl-to-methane under CIP stress, while functional gene abundance associated with CIP degradation enhanced partially, about encoding translocases, oxidoreductases, lyases, and ligases. Therefore, BC can be added to AD under CIP press to address its inhibited methanogenic performance.

On the mechanism and energetics of electrochemical alloy formation between mercury and platinum for mercury removal from aqueous solutions

Mercury pollution is an acute global concern threatening the health of humans and wildlife. Thus, there is a need for new and improved techniques to reduce emissions and remove toxic mercury from aqueous environments. Electrochemical alloy formation, specifically between mercury ions in aqueous solution and a platinum electrode, emerges as a promising solution. Through analysis of reaction mechanisms and energetics related to the formation and dissolution of the PtHg4 alloy, this study aims to deepen our understanding of the underlying processes of effective electrochemical mercury removal. Potentiodynamic measurements indicate rapid alloy formation at a clean platinum surface, proceeding with only trace amounts of metallic mercury on the surface. However, once the electrode surface has sufficient mercury coverage with an alloy thickness of around 1.5 nm, clear evidence of metallic mercury on the surface is observed. Furthermore, the amount of absorbed mercury on the cathode increases linearly in time. The onset potential for the alloy formation is experimentally determined using electrochemical quartz crystal microbalance with dissipation monitoring to be approximately 0.64 V vs. SHE, and the alloy dissolution (oxidation) onset potential is found to be approximately 0.98 V vs. SHE, at a mercury ion concentration of 10 mg/L. Density functional theory calculations are used to provide a theoretical value for the reversible potential from a thermodynamics perspective, yielding a value of 0.78 V vs. SHE at a mercury ion concentration of 10 mg/L. This value is in excellent agreement with the experimental results, suggesting an overpotential of about 0.14 and 0.20 V for the alloy formation and oxidation, respectively. These findings provide important information on the reaction mechanisms and overpotentials of the PtHg4 alloy formation and dissolution, which are key factors for development of large-scale mercury removal based on this technique, as well as fundamental understanding of the electrochemical alloy formation between mercury ions and platinum.

Expanding cyclodextrin use in normal phase and super/subcritical fluid chromatographic modes for the chiral separation of 1,4-dihydropyridines

Cyclodextrin-based stationary phases are important chiral selectors in liquid chromatography. These chiral selectors are most commonly used in the reversed-phase mode because native cyclodextrin assumes a torus conformation with a hydrophobic cavity, facilitating inclusion complexation in aqueous environments. However, the value of native and aliphatic-derivatized cyclodextrins in other modes, such as the normal phase liquid chromatography (NPLC) or super/subcritical fluid chromatography (SFC), remains unexplored. In this work, we report chiral separations of pharmaceutically relevant compounds with the 1,4-dihydropyridine (DHP) scaffold on a 2-hydroxypropyl-β-cyclodextrin (CD-RSP) stationary phase in NPLC and SFC modes. Although CD-RSP is conventionally considered only effective in the reversed-phase mode, we show that these compounds tend to separate better in other modes. This is particularly apparent for analytes with hydrogen-bonding moieties. We propose that the separation mechanism primarily depends on external adsorption rather than inclusion complexation. The negligible impact of a complexation-competitive additive on retention in non-aqueous modes further supports this claim. Additionally, van Deemter analysis demonstrated the efficiency and environmental benefit of using this stationary phase in the SFC mode, further highlighting the promise of aliphatic derivatized cyclodextrin stationary phases for greener separations.

Synthesis and functional mechanism evaluation of novel polymer-graphene oxide-biochar nanocomposite for efficient removal of diethyl phthalate

Phthalates, categorized as a main constituent of endocrine-disrupting chemicals (EDCs), are present in polymeric products. These substances can enter the environment through several pathways, including improper handling, which leads to their presence in toilet water, floor washings, surface runoff, and landfill leachate. This study focuses on the performance analysis of nanocomposite materials made of polymer (polypyrrole), quasi-metal (graphene oxide), and biochar (from palmyra seed) for the elimination of diethyl phthalates (DEP) from aqueous environments. Scanning electron microscope (SEM), X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy (FTIR) were used to describe the nanocomposite characteristics. The experimental results supported a chemisorption process by agreeing well with the pseudo-second order. The Langmuir isotherm explained the DEP sorption data, which aligned to monolayer DEP adsorption on the nanocomposite surface. With a binding affinity of −13.36 (kcal/mol) and the highest docking score, Diethyl phthalates and graphene oxide interaction is validated. The produced nanocomposite is suggested as a possible alternative for the sorption of DEP. Future applications could benefit from the higher adsorption capacity, and environmental friendliness of nanocomposites.

Hydrothermal fabrication of composite chitosan grafted salicylaldehyde/coal fly ash/algae for malachite green dye removal: A statistical optimization

In this study, chitosan grafted salicylaldehyde/coal fly ash/algae (Chi-SL/CFA/Alg) was synthesized by assistance of hydrothermal process to be an effective adsorbent to remove cationic dye (malachite green: MG) from water. The physicochemical properties of the Chi-SL/CFA/Alg biomaterial were examined using SEM-EDX, pHpzc, specific surface area (BET), and FTIR analyses. The optimization process of the adsorption operation parameters for MG removal by Chi-SL/CFA/Alg were optimized using a Box-Behnken design (BBD). The selected adsorption operation parameters Chi-SL/CFA/Alg dosage (A: 0.02–0.1 g/100 mL), solution pH (B: 4–8), and contact time (C: 20–360 min). Analysis of variance (ANOVA) test was applied to determine the significant interaction between the adsorption operation parameters and to validate BBD output. The adsorption kinetics and isotherms of MG dye by Chi-SL/CFA/Alg were well described by pseudo-second order (PSO) kinetic and Freundlich isotherm model respectively. Thus, the maximum adsorption capacity (qmax) of MG dye by Chi-SL/CFA/Alg was found to be 493.7 mg/g at basic pH environment (pH = 8) and working temperature 25 °C. The adsorption mechanism can be ascribed to various interactions, including hydrogen bonding, π-π interactions, electrostatic attraction, and n-π interactions. Thus, Chi-SL/CFA/Alg can be considered as preferable and potential adsorbent for removing cationic dye from aqueous environment.