Partial Adsorption Research Articles

Latest trends in the environmental analysis of PFAS including nontarget analysis and EOF-, AOF-, and TOP-based methodologies.

Ubiquitous environmental occurrence of per- and polyfluoroalkyl substances (PFAS) underscores the critical need to broaden investigative efforts in effective screening, risk assessment, and remediation. Owing to thebroad spectrum of PFAS, various analytical techniques have been extensively utilized to attain inclusivity, with notable attention given to methods such as extractable organic fluorine (EOF), adsorbable organic fluorine (AOF), and the total oxidizable precursor (TOP) assay. These techniques expand the scope of PFAS analysis by estimating perfluoroalkyl acid precursors or the total organochlorine fraction. This review offers a comprehensive comparative overview of up-to-date methodologies, alongside acknowledging the inherent limitations associated with their applications. When coupled with target analysis via low-resolution tandem mass spectrometry, these techniques offer a potential estimation of total PFAS concentrations. Yet, analytical challenges such as the limited availability of reference analytical standards, partial PFAS adsorption, and the entrapment of fluorinated inorganic anions on adsorbent materials often restrict the comprehensiveness of PFAS analysis. So, integrating nontarget analysis using high-resolution mass spectrometry (HRMS) tools fortifies these PFAS mass balance approaches, enabling the development of a more holistic approach for anenvironmental analysis framework. This review provides additional insights into the comparative advantages of PFAS analytical approaches and explores various data prioritization strategies in nontarget screening methods. It advocates for the necessary optimization of PFAS extraction methods, asserting that integrating the nontarget approach would foster the establishment of a comprehensive monitoring framework across diverse environmental matrices. Such integration holds promise for enhancing scientific comprehension of PFAS contamination across diverse environmental matrices.

Elucidating the Molecular Mechanisms by which Porous Polymer Networks Affect Structure, Aging Propensity, and Selectivity of Microporous Glassy Polymer Membranes using a Multiscale Approach.

Microporous glassy polymer membranes suffer from physical aging, which adversely affects their performance in the short time frame. We show that the aging propensity of a model microporous polymer, poly(1-trimethylsilyl-1-propyne) (PTMSP), can be effectively mitigated by blending with as little as 5 wt % porous polymer network (PPN) composed of triptycene and isatin. The aging behavior of these materials was monitored via N2 pure gas permeability measurements over the course of 3 weeks, showing a 14% decline in PTMSP blended with 5 wt % PPN vs a 41% decline in neat PTMSP. Noteworthy, PPNs are 2 orders of magnitude cheaper than the porous aromatic frameworks previously used to control PTMSP aging. A variety of experimental and computational techniques, such as Positron Annihilation Lifetime Spectroscopy (PALS), free volume measurements, cross-polarization/magic angle spinning (CP/MAS) 13C NMR, transport measurements and molecular dynamics (MD) simulations were used to uncover the molecular mechanisms leading to enhanced aging resistance. We show that partial PTMSP chain adsorption into the PPN porosity reduces the PTMSP local segmental mobility, leading to improved aging resistance. Permeability coefficients were broken into their elementary sorption and diffusion contributions, to elucidate the mechanism by which the reduced PTMSP local segmental mobility affects selectivity in gas separation applications. Finally, we demonstrate that in these systems, where both chemical and physical interactions take place, transport coefficients must be corrected for thermodynamic nonidealities to avoid erroneous interpretation of the results.

Adsorptive removal of microplastics from aquatic environments using coal gasification slag-based adsorbent in a liquid–solid fluidized bed

Microplastics (MPs) are emerging pollutants in aquatic environments that threaten ecological health. This study investigated the adsorption process and mechanism of a coal gasification slag-based adsorbent in a liquid–solid fluidized bed to remove MPs from an aquatic environment. The results showed that the coal gasification slag-based adsorbent had high MP adsorptive removal efficiency of up to 1400 mg/g and adsorption-removal efficiency of 99.2 %. The adsorption process was mainly dominated by electrostatic attraction, π-π absorption, and surface complexation, supplemented by partial physical adsorption. The adsorbent dosage mo was the dominant factor affecting the adsorption performance of the liquid–solid fluidized bed for the continuous adsorption of MPs, followed by the initial MP concentration co and ascending water velocity vt. At a suitable combination of operating parameters (co = 250 mg/L; mo = 2.5 g; vt = 0.11 m/s), the adsorption saturation level of the liquid–solid fluidized bed reached 0.95, which was higher than that of the traditional fixed bed (0.91), indicating good MP adsorption performance. This study provides a new technical approach for MP removal from aquatic environments that is conducive to the industrial application of fluidized beds in the field of wastewater treatment.

Room temperature atomic layer deposition of zinc titanium oxide using sequential adsorption of dimethyl zinc and tetrakis(dimethylamino)titanium

Complex oxide films of TiO2 and ZnO are deposited by RT atomic layer deposition (ALD) with a sequential adsorption process. In this ALD, a Zn precursor of dimethyl zinc (DMZ) and a Ti precursor of tetrakis(dimethylamino)titanium (TDMAT) are used. In the sequential adsorption step, the DMZ saturation on the surface is followed by partial adsorption of TDMAT. It is assumed that the TDMAT molecule is adsorbed on the DMZ uncovered area. The mixed layer of DMZ and TDMAT is formed in the adsorption step, followed by being oxidized with the plasma-excited humidified Ar. All the ALD processes are performed at RT without any sample heating in the ALD chamber. The growth per cycle of the balanced Zn and Ti oxide deposition is recorded at 0.086 nm/cycle. The mixing ratio of Zn and Ti is controlled by the TDMAT exposure in the adsorption step. In this study, the reaction model and the related rate equations to calculate the mixing concentration ratio are proposed based on the in situ observation of the surface reaction by IR absorption spectroscopy.

A density functional theory research on the interaction of H2X molecules with the Al2C nanosheet (X = O, S, Se, Te)

The potential application of the 2D material Al2C, as catalysts and as sensor of the hazardous molecules H2S, H2Se and H2Te, is studied using theoretical methods. Density functional theory (DFT) has been applied to study the interaction between the pristine Al2C nanosheet and small molecules, such as H2O, H2S, H2Se and H2Te. Results show the Al2C nanosheet is a promising material to dissociate the studied molecules as well as its potential use as sensor of these molecules in molecular or dissociated state. Molecular interactions are weak even considering the London dispersion forces. Partial dissociative adsorption is strongly preferred to molecular adsorption for all four molecules. Applying the climbing image NEB method, the activation energy for H2O dissociation to OH-H is calculated in ≈ 0.1 eV whereas it is just a few meV for H2S, H2Se and H2Te partial dissociation. The calculated energy gap for the clean Al2C nanosheet is 1.078 eV whereas it is increased to 1.371, 1.338, 1.379 and 1.416 eV for molecular adsorption and to 1.209, 1.363, 1.370 and 1.388 eV for partial dissociative adsorption.

Treatment of Waters Having Different Ionic Composition and pH with Natural Zeolites from Bulgaria

The migration of 32 elements from natural zeolitized tuffs from the Beli Plast and Golobradovo deposits (Bulgaria) was determined in ultrapure, tap, mineral, and coal mine waters in order to evaluate their desorption and adsorption properties. The tuffs are Ca-K-Na and contain clinoptilolite (90 and 78wt.%, respectively), plagioclase, sanidine, opal-CT, mica, quartz, montmorillonite, goethite, calcite, ankerite, apatite, and monazite. The desorption properties are best revealed during the treatment of ultrapure, tap, and mineral water, whereas the adsorption properties are best manifested in coal mine water treatment. The concentrations of Al, Si, Fe, Na, Mn, F, K, Pb, and U increase in the treated ultrapure, tap, and mineral water, while the content of K, Be, Pb, and F increase in the treated mine water. The tuffs show selective partial or complete adsorption of Na, Mg, Sr, Li, Be, Mn, Fe, Co, Ni, Cu, Zn, Al, Pb, U, and SO42−. They demonstrate the ability to neutralize acidic and alkaline pH. Sources of F are presumed to be clinoptilolite and montmorillonite. The usage of zeolitized tuffs for at-home drinking water treatment has to be performed with caution due to the migration of potentially toxic and toxic elements.

An Innovative Sunlight‐Driven Device for Photocatalytic Drugs Degradation: from laboratory‐ to real‐Scale Application. A First Step Toward Vulnerable Communities

AbstractFreshwater represents one of the most precious resources on the planet, so it is fundamental to preserve it. In this work, an innovative sunlight‐driven device composed of bismuth oxybromide (BiOBr) grown on a material derived from natural sources, i.e., Lightweight Expanded Clay Aggregates (LECA), is developed to clean surface waters under natural solar light irradiation. For this purpose, the photodegradation of two non‐steroidal anti‐inflammatory drugs, ibuprofen, and diclofenac, is investigated under varying operative conditions. Laboratory‐ and real‐scale experiments reveal that the fabricated floating BiOBr/LECA photocatalyst fully degrades diclofenac, whereas limited abatement of ibuprofen is observed. Based on the identification of specific transformation products (TPs) during the degradation, this behavior seems to be strongly related to the different structures of the two drugs. In fact, the main TP produced during diclofenac degradation derives from dechlorination and ring condensation: this type of photocatalytic degradation pathway is generally favored over the C─C bonds's cleavage, which is a unique possibility for IBU abatement. Moreover, the potential partial adsorption of these species on the photocatalyst's active sites can cause their deactivation. Finally, reusability tests demonstrate the high stability of the floating composite.

Development of a laboratory setup for destruction of oil-water emulsions

The work describes a laboratory setup developed by the authors for destruction of oil-water emulsions. The setup can be used in chemical analytical testing laboratories as new auxiliary equipment for preparing samples of crude oils, which are oil-water emulsions, for obtaining dehydrated oil. The setup includes two borosilicate glass units: heating unit and desiccating unit. The heating unit consists of a conical vessel equipped with a heating element for programmable heating and thermostating of the vessel. The desiccating unit consists of a vessel with a drain hole at the bottom, into which, if necessary, a water-absorbing reagent (calcium chloride) is placed for deeper dehydration of the separated oil phase. The units are connected to each other by a glass adapter, which is equipped with two PTFE or KhN-1 type taps, for collecting water and oil phases into different receiving bottles. Feasibility of using calcium chloride as a drying agent was confirmed by a series of experiments on a model oil sample, in which fractions that boiled away at temperatures below 300 °C were preliminary removed. The data obtained confirmed the absence of partial adsorption of resinous-asphaltene substances during the passage of the separated oil phase through the drying reagent layer. Metrological characteristics of determining separated water fraction were calculated to assess the effectiveness of the laboratory installation. The result of using the developed laboratory setup is the complete destruction of direct and reverse type water-oil emulsions of varying degrees of stability, which could not be demulsified by known laboratory methods. As a result, separated oil phases with a water content of below 1% were obtained, which allows carrying out laboratory studies of oils to determine their composition and properties both to characterize the oils themselves and to establish the reasons for stability of analyzed emulsions.

Perchlorate uptake by poly-(diallydimethylammonium chloride) functionalized montmorillonites

Montmorillonite (Mt) is proposed as a promising adsorbent for removing contaminants from water, yet it is unclear whether and how the layer charge density (LCD) of Mt. affects its hydration properties, especially for the capturing performance of anions by polyelectrolyte modified Mt. Here, the feasibility and performance of perchlorate uptake by poly-(diallydimethylammonium chloride) (PDDA) functionalized Mt. (PDDA-Mtx) with different LCD were investigated. PDDA species were loaded via partial intercalation or adsorption on the surface/end sites of Mt. The CEC of Ca-Mtx increased with increasing LCD, while on the contrary for colloidal valence. The perchlorate uptake by Ca-Mtx can be significantly improved by introducing PDDA species. As expected, the PDDA-Mt0.3 showed superior perchlorate capture of up to 0.80 mmol/g due to the relatively high positive zeta potential and loading of un-ionized PDDA. The perchlorate uptake by PDDA-Mtx still maintained largely despite a slight decrease in the presence of co-competing anions NO-3, SO2–4 and PO3–4. The capture behaviors were well characterized by the pseudo-second-order and Langmuir isotherm models, and the natures of spontaneous and endothermic were demonstrated by thermodynamic analysis. Anion exchange and electrostatic were the dominant ways in which perchlorate was captured onto PDDA-Mtx.

Colorimetric detection of ammonia using an adhesive, stretchable hydrogel patch

Currently, because of the harmful effects of ammonia on human health, ecosystems, and overall air quality, the development of easily usable, portable, cost-effective, and field-deployable ammonia sensors is urgently necessary. This study focused on the development of an ammonia-sensing patch composed of a fibrous sensing component and hydrogel-like support substrate. This sensor was capable of colorimetric ammonia sensing with a limit of detection of 0.2454 ppm. The fibrous sensing region was prepared by electrospinning a mixture of poly(acrylic acid) (PAA) and poly(vinyl alcohol) (PVA), followed by the partial crosslinking and adsorption of transition metal ions such as copper. A support substrate was prepared by combining PVA and borate compounds, resulting in a stretchable, adhesive, and self-healing hydrogel. The ammonia-sensing patch demonstrated enough adhesion to various substrates and could be used as a sticky plaster-type sensor that also function as a sealant. The patch exhibited a distinct color change from blue–green to blue upon exposure to ammonia gas, which was attributed to the formation of a complex between the copper ions and ammonia. The color change was analyzed by monitoring the average RGB intensities using a charge-coupled device (CCD) camera and a MATLAB program. Additionally, we assessed the patch's capability of detecting and sealing ammonia leakage through experiments conducted in a simulated gas leakage setup. Overall, the developed ammonia-sensing patch shows promise for the real-time colorimetric detection of ammonia gas and has potential applications in gas leakage detection and prevention.

Molecular structure of dissolved organic carbon in a sandy soil receiving contrasting quality organic residues

Decomposing plant residues release plant-derived dissolved organic carbon (DOC) which can be transformed by microorganisms resulting in microbial-derived DOC (DOC biological function). The adsorbability of DOC to mineral surfaces, determined by DOC chemistry (DOC chemical function), can affect its vertical distribution down soil profiles (D). This study investigated the temporal characteristics (T) and functions (bioavailability, adsorbability) of DOC across the profile of a sandy soil by using chemically contrasting quality (Q) residues: 1) high-cellulose rice straw (RS), 2) nitrogen-rich groundnut stover (GN), 3) lignin-rich dipterocarp leaf litter (DP), and 4) medium-nitrogen and -lignin tamarind leaf litter (TM). Soil samples were collected at two depths (0–15 cm and 60–80 cm) two and eight weeks after residue application, and water-extractable DOC was determined. For the first time, the chemical structure of the extracted DOC was characterized using pyrolysis coupled with mid-infrared spectroscopy (Py-MIRS). The dominant functional groups found in all DOC samples were aromatic, carboxyl, and polysaccharide compounds. The interactive effects of Q, T, and D (soil depth) influenced DOC-polysaccharides, with the most pronounced effect observed in the RS treatment during the early stage, indicating that DOC-polysaccharides were mainly plant-derived. Evidence of partial adsorption of DOC-aromatics and DOC-carboxyls was found in topsoils. These high molecular weight-DOC functional groups may have displaced adsorbed polysaccharides, resulting in higher subsoil DOC-polysaccharides than topsoil, especially under DP and TM. During the later stage, topsoil DOC-polysaccharides were negatively related to microbial metabolic quotient (qCO2) (R2 = 0.938). This relationship led to our hypothesis that the dominant source of DOC-polysaccharides, particularly in the TM treatment, was of microbial origin. A novel discovery from this study is that the chemical quality of plant residues, which serve as the source of DOC, determines the origin of the polysaccharides in DOC. This origin transitioned from plant-derived to microbial-derived as decomposition progressed. Importantly, the presented findings were the first of its kind based on a field experiment.

Encounter-based reaction-subdiffusion model I: surface adsorption and the local time propagator

In this paper, we develop an encounter-based model of partial surface adsorption for fractional diffusion in a bounded domain. We take the probability of adsorption to depend on the amount of particle-surface contact time, as specified by a Brownian functional known as the boundary local time . If the rate of adsorption is state dependent, then the adsorption process is non-Markovian, reflecting the fact that surface activation/deactivation proceeds progressively by repeated particle encounters. The generalized adsorption event is identified as the first time that the local time crosses a randomly generated threshold. Different models of adsorption (Markovian and non-Markovian) then correspond to different choices for the random threshold probability density . The marginal probability density for particle position prior to absorption depends on ψ and the joint probability density for the pair , also known as the local time propagator. In the case of normal diffusion one can use a Feynman–Kac formula to derive an evolution equation for the propagator. Here we derive the local time propagator equation for fractional diffusion by taking a continuum limit of a heavy-tailed continuous-time random walk (CTRW). We begin by considering a CTRW on a one-dimensional lattice with a reflecting boundary at n = 0. We derive an evolution equation for the joint probability density of the particle location and the amount of time spent at the origin. The continuum limit involves rescaling by a factor , where is the lattice spacing. In the limit , the rescaled functional becomes the Brownian local time at x = 0. We use our encounter-based model to investigate the effects of subdiffusion and non-Markovian adsorption on the long-time behavior of the first passage time (FPT) density in a finite interval with a reflecting boundary at x = L. In particular, we determine how the choice of function ψ affects the large-t power law decay of the FPT density. Finally, we indicate how to extend the model to higher spatial dimensions.

Role of concentration and hydrophobic nature of weak polyelectrolytes on adsorption structure and thermodynamics at oil-water interface: Study of several carboxylate polymers

Intermolecular structure, conformations, solvation and adsorption characteristics of four partially ionized polycarboxylic acids syndiotactic-poly(acrylic acid) (s-PAA), syndiotactic-poly(methacrylic acid) (s-PMA), isotactic-poly(methacrylic acid) (i-PMA) and atactic-poly(ethacrylic acid) (a-PEA) at oil (CCl4) - water interface is studied by molecular dynamics simulations over the range from dilute to monolayer coverage. Linearity and slope of Θ-Γ curves are correlated to conformational invariance and extent of adsorption (partial vs complete) respectively, within the range of concentration of study. Adsorption of i-PMA and a-PEA chains occurs deeper into the oil-side of interface region as driven by the greater hydrophobicity of these polymers. Higher tendency of highly extended s-PMA to desorb from the interface as compared to strong adsorption of compact coiled i-PMA is driven by their solvation behavior dictated by aspects of structural partitioning of chemical groups with respect to the solvents of the two phases. Hydrophobic side-group in the polyelectrolyte chain is responsible for the slower dynamics of the backbone. The observed variation in thickness of adsorbed layer and fractional interface coverage with concentration suggest partial adsorption of chain segments beyond saturation of interface rather than coiling of chains to accommodate additional chains. While a-PEA exhibits greater variation in interfacial tension, the change in electric potential difference across the interface indicates weak adsorption by s-PMA. The influence of the tacticity of PMA on dynamics and distribution of counter-ions is in agreement with experimental results. Results provide a significant advancement in our understanding of polyelectrolyte and polymer adsorption at oil-water liquid interface.

Development of microfluidic chip flowmeter-based constant pressure system for analysing the hydrogen adsorption performance of non-evaporable getters

BackgroundAs one of the primary residual gases in vacuum, hydrogen affects the performance of MEMS devices. It commonly uses a non-evaporable getter (NEG) to adsorb hydrogen in this case. One of the standard test methods for NEG is the constant pressure method. However, most constant pressure test systems control the intake flow by valves or small orifices. These methods are crude and limit the reliability of the result. Therefore, it is necessary to provide a stable intake flow method for the constant pressure test system to improve the accuracy of the test. ResultsWe demonstrate a constant pressure system based on the microfluidic chip flowmeter to evaluate the hydrogen adsorption performance of non-evaporable getters in this paper. The microfluidic chip features microchannels with a height of around 100 nm. It is encapsulated with standard tube fittings, with leakage of less than 1 × 10−13 Pa ∙ m3∙ s−1. The conductance of the flowmeter is 10−12 m3∙ s−1, and the upper-pressure limit of the molecular flow is 105 Pa. It can control the intake flow of the adapted constant pressure test system from 10−11 to 10−7 Pa ∙ m3∙ s−1. Using this system, we tested the hydrogen adsorption capability of the Zr–Fe getter at different working pressures/temperatures and the types of gas it adsorbs were analysed. The results showed that the adsorbent has a noticeable adsorption effect on H2 and a partial adsorption effect on H2O, CO and CO2. SignificanceThe microfluidic chip flowmeter can provide a stable intake molecular flow for the adapted constant pressure test system. It ensures the reliability of the measurement results. The ability of the flowmeter to offer tiny flow rates at 105 Pa can drastically simplify the test system and is more user-friendly for getters tests with poor adsorption performance. It has positive significance for industrial research on the non-evaporable getter.

Reduction mechanism of bamboo powder pyrolysis in selective lithium extraction from spent lithium-ion batteries

In light of the increase in demand for lithium resources, selective recovery of lithium from spent lithium-ion batteries (LIBs) is becoming increasingly important. In the preferential lithium extraction process, the choice of reducing agent is crucial, which affects the efficiency of Li+ release. Here, a novel biomass reducing agent waste bamboo powder (BP) is proposed. The thermal reduction mechanism of BP on spent cathode powder (SCP) is explored in detail, and the effect of BP before and after carbonization on the lithium extraction effect is investigated. Based on the regulation of roasting parameters, the SCP can be reduced to Li2CO3, Ni, Co and MnO under the optimal conditions of 650 ℃ for 1.5 h with 1:1 mass ratio of BP/SCP. Furthermore, through thermodynamic calculations and physicochemical characterizations, it is found that the addition of gas-solid reaction in the BP reduction process is superior to the carbonized non-activated carbon (NC) and activated carbon (AC). Moreover, the large specific surface area of 1145.725 m2 g−1 for AC will lead to partial adsorption of lithium during the water leaching process. Finally, more than 99% of lithium is preferentially recovered from the reducing residue through a two-stage leaching process of water leaching and low concentration acid leaching. Water leaching process can recover 82.6% of lithium and the model of physical dissolution kinetics are constructed and systematically studied. This research achieves low-cost, green and selective recovery of lithium from spent LIBs, which has broad industrial application prospects.

Effect of Natural Coagulants on the Treatment of Municipal Wastewater

Nowadays, the study of the natural coagulants to treat wastewater has become a growing interest to the environmental researchers around the world as its numerous advantages over chemical coagulants. In this study, the effect of banana peel powder and banana stem powder as natural coagulant on the treatment of municipal wastewater was investigated. Wastewater samples were collected from two different primary drains located near Padma garden and Bornali within Rajshahi city corporation area. The collected wastewater samples were characterized based on turbidity, pH, conductivity, TDS, TSS, TS, alkalinity, acidity and organic content and also compared with maximum permissible limits before going treatment. The worst wastewater sample was treated with varying coagulant doses, contact time, speed and pH. The effectiveness of natural coagulants was evaluated based on the percentage removal of turbidity, alkalinity and acidity. The highest removal of turbidity, alkalinity and acidity were obtained 93.5%, 67.3% and 65.5% by banana peel powder and 93.4%, 71% and 72% by banana stem powder respectively. Therefore, the result revealed that both banana peel powder and banana stem powder had capability to treat municipal wastewater as natural coagulant. Higher treatment conditions were not economically feasible because it did not significantly remove the pollutants. The removal of alkalinity and acidity indicated that it was a partial coagulation and partial adsorption process in which both materials also had high adsorption capacities.

Development, testing, and molecular dynamics simulation of a membrane that resists fouling by gel pollutants for humidification–dehumidification–type seawater desalination

Humidification-dehumidification-type seawater desalination is an effective technology for solving the ongoing water shortage issue. As organic acid-rich seawater contains many amphiphilic gel pollutants, it is necessary to develop a membrane with anti-gel-fouling characteristics. Most of the previous studies have focused on the hydrophobic functionalisation of the membrane surface or the introduction of certain anti-fouling components to remove contaminants, such as salts or proteins, from membranes. In contrast, the contamination of membranes with gels has rarely been investigated. In this study, a commercial membrane was modified with citric acid to overcome the contamination of the membrane surface with gel during organic acid-rich seawater desalination. A novel functional membrane was prepared by introducing citric acid into a polyvinylidene fluoride (PVDF) membrane. Then, SiO2 was loaded onto the membrane surface to form an electronegative layer and also improve its hydrophobicity by increasing the surface roughness. The SiO2-loaded membrane was further modified with low-surface-energy fluoroalkylsilane to render the membrane surface hydrophobic. During water treatment, citric acid combined with Ca2+ to form soluble complexes on the membrane surface, preventing the formation of gel. Preferential selection and steric hindrance prevented the aggregation of gelatinous particles on the membrane surface. The formation of the hydration layer prevents the partial adsorption of the hydrophobic gel on the membrane surface. Further, the highly electronegative layer on the membrane surface synergistically reduced the adsorption of the most electronegative gel. The so-modified PVDF membrane was used to treat brine with a high gel content, and the structural parameters, moisture permeability, and resistance to gel fouling of the new functional membrane were evaluated. In addition, molecular dynamics simulations were performed to clarify the mechanism through which the modified membrane resists gel fouling. The new functional membrane could satisfactorily prevent gel pollution during seawater desalination.

The incorporation of curcuminoids in gamma-cyclodextrins improves their poor bioaccessibility, which is due to both their very low incorporation into mixed micelles and their partial adsorption on food.

Curcuminoids, found in turmeric and many dietary supplements, usually consist of a mixture of curcumin (CUR), demethoxycurcumin (dCUR) and bisdemethoxycurcumin (bdCUR). CUR displays low bioavailability, partly due to poor solubilization in the intestinal lumen during digestion, while data for dCUR and bdCUR are scarce. We aimed to investigate the bioaccessibility of curcuminoids from turmeric extracts or from gamma-cyclodextrins, considering potential interactions with foods. USING AN IN VITRO DIGESTION MODEL (CORRELATION WITH CUR BIOAVAILABILITY: : r = 0.99), we showed that curcuminoid bioaccessibility from turmeric extract with no food was low: bdCUR (11.5 ± 0.6%)>dCUR (1.8 ± 0.1%)>CUR (0.8±0.1%). Curcuminoids incorporated into gamma-cyclodextrins displayed higher bioaccessibilities (bdCUR: 21.1 ± 1.6%; dCUR: 14.3 ± 0.9%; CUR: 11.9 ± 0.7). Curcuminoid bioaccessibility was highest with no food (common turmeric extract: 2.0 ± 0.1%; gamma-cyclodextrins: 12.4 ± 0.8%) and decreased with a meat- and potato-based meal (common turmeric extract: 1.1 ± 0.2%; gamma-cyclodextrins: 2.4 ± 0.3%) or a wheat-based meal (common turmeric extract: 0.1 ± 0.0%; gamma-cyclodextrins: 0.3 ± 0.1%). Curcuminoids exhibited low (<10%) incorporation efficiencies into synthetic mixed micelles, with bdCUR>dCUR>CUR. bdCUR and dCUR show greater bioaccessibilities versus CUR. Foods diminish curcuminoid bioaccessibility, likely by adsorption mechanisms. Gamma-cyclodextrins improve curcuminoid bioaccessibility. This article is protected by copyright. All rights reserved.

Coexistence of microplastics alters the inhibitory effect of antibiotics on sludge anaerobic digestion

Microplastics and antibiotics are emerging pollutants that inevitably enter the sludge anaerobic digestion system. Current studies mainly focused on the individual effects of microplastics or antibiotics on methane generation. However, there may also be complex reactions between them and their combine effects on anaerobic digestion remain unclear. This study revealed the combined influencing mechanism of polyamide and ofloxacin through batch and semi-continuous tests. Brief exposure to ofloxacin was detrimental to methane production. The coexistence of polyamide enabled partial adsorption of ofloxacin, which effectively mitigates the inhibitory effect of ofloxacin at low concentrations. Polyamide also facilitated the colonization of hydrolytic bacteria and acidogens, such as Hydrogenispora, and promoted the conversion of organic matter to acetate. However, polyamide could not effectively alleviate the inhibitory effect of excess ofloxacin on anaerobic digestion. Ofloxacin at high concentrations stimulated the release of humic acid, reduced methane production by more than 80%, and changed the predominant methanogenesis pathway from acetoclastic methanogenesis to hydrogenotrophic methanogenesis. Acidogenesis and methanogenesis pathways were restructured to further explore the effect of ofloxacin on the metabolic potentials of microorganisms. Metagenomic analysis revealed that most of functional genes associated with glycolysis, amino acid metabolism and methanogenesis were down regulated under long-term stress of high concentration of ofloxacin. This study elucidated the microbial process of organic matter conversion inhibition by ofloxacin, shed light on the combined effects of polyamide and ofloxacin on anaerobic digestion and provided new insights for assessing the impact of multiple pollutants on the safe disposal of sludge.

The behavior of thiacarbocyanine dyes on the surface of few-layered hexagonal boron nitride

The adsorption and self-assembly of several thiacarbocyanine dyes on hexagonal boron nitride (hBN) was investigated by combining steady-state spectroscopy and atomic force microscopy. The adsorption isotherms indicate that at saturation the density of the cationic TDC (5,5-dichloro-3-3′-diethyl-9-ethyl-thiacarbocyanine) molecules on hBN is similar to that of TD2 (3-3′-diethyl-9-ethyl-thiacarbocyanine) molecules, while the densities of TD0 (3-3′-diethyl-thiacarbocyanine) molecules and the zwitterionic THIATS (5,5-dichloro-3-3′-disulfopropyl-9-ethyl-thiacarbocyanine) molecules are significantly higher. The intermolecular distances between neighboring adsorbed dyes, calculated from these saturation densities indicate a flat-on adsorption for TDC, TD2 and TD0 and a partial edge-on adsorption for THIATS. AFM micrographs of the adsorbed TDC, TD0 and THIATS molecules indicate that already at low dye concentrations in the solution, where only a small fraction of the hBN surface is covered, the dye molecules already form upon adsorption to hBN aggregates of at least 10 nm, separated by areas where no adsorbed dye molecules can be detected. The resolution of the micrographs was however insufficient to show details of the packing of the adsorbed molecules. For THIATS, the thickness of the adsorbed layer is compatible with an edge-on adsorption, while for TDC and TD0, the thickness of the adsorbed layer is twice the thickness expected for flat-on adsorption. The exciton interaction extracted from the steady-state spectroscopy of the adsorbed dyes is much smaller than observed for H- or J-aggregates of the same dyes in solution or adsorbed to other surfaces such as Langmuir films or silver halides. For TDC, TD2 and TD0, the values of the exciton interaction are compatible with a close packed flat-on adsorption. Hence, optimizing the interaction between the adsorbed dye and hBN rather than between the adsorbed dye molecules governs the packing of the adsorbed dye molecules. The observation of the spectral shifts attributed to the exciton interaction at low average coverage of the hBN surface indicates that the exciton interaction already occurs at low coverage of the hBN surface. This observation is in agreement with the AFM micrographs, which show clustering of the adsorbed dye molecules already at low coverages.