Sorption Experiments Research Articles

Amine‐Functionalized Triazolate‐Based Metal–Organic Frameworks for Enhanced Diluted CO2 Capture Performance

AbstractEfficient CO2 capture at concentrations between 400–2000 ppm is essential for maintaining air quality in a habitable environment and advancing carbon capture technologies. This study introduces NICS‐24 (National Institute of Chemistry Structures No. 24), a Zn‐oxalate 3,5‐diamino‐1,2,4‐triazolate framework with two distinct square‐shaped channels, designed to enhance CO2 capture at indoor‐relevant concentrations. NICS‐24 exhibits a CO2 uptake of 0.7 mmol/g at 2 mbar and 25 °C, significantly outperforming the compositionally related Zn‐oxalate 1,2,4‐triazolate – CALF‐20 (0.17 mmol/g). Improved performance is attributed to amino‐functions that enhance CO2 binding and enable superior selectivity over N2 and O2, achieving 8‐fold and 30‐fold improvements, respectively, in simulated CO2/N2 and CO2/O2 atmospheric ratios. In humid environments, NICS‐24 retained structural integrity but exhibited an 85 % reduction in CO2 capacity due to competitive water adsorption. Breakthrough sorption experiments, atomistic NMR analysis, and DFT calculations revealed that water preferentially adsorbs over CO2 due to strong hydrogen‐bonding interactions within the framework. Gained understanding of the interaction between CO2 and H2O within the MOF framework could guide the modification via rational design with improved performance under real‐world conditions.

Amine-Functionalized Triazolate-Based Metal-Organic Frameworks for Enhanced Diluted CO2 Capture Performance.

Efficient CO2 capture at concentrations between 400-2000 ppm is essential for maintaining air quality in a habitable environment and advancing carbon capture technologies. This study introduces NICS-24 (National Institute of Chemistry Structures No. 24), a Zn-oxalate 3,5-diamino-1,2,4-triazolate framework with two distinct square-shaped channels, designed to enhance CO2 capture at indoor-relevant concentrations. NICS-24 exhibits a CO2 uptake of 0.7 mmol/g at 2 mbar and 25 °C, significantly outperforming the compositionally related Zn-oxalate 1,2,4-triazolate - CALF-20 (0.17 mmol/g). Improved performance is attributed to amino-functions that enhance CO2 binding and enable superior selectivity over N2 and O2, achieving 8-fold and 30-fold improvements, respectively, in simulated CO2/N2 and CO2/O2 atmospheric ratios. In humid environments, NICS-24 retained structural integrity but exhibited an 85 % reduction in CO2 capacity due to competitive water adsorption. Breakthrough sorption experiments, atomistic NMR analysis, and DFT calculations revealed that water preferentially adsorbs over CO2 due to strong hydrogen-bonding interactions within the framework. Gained understanding of the interaction between CO2 and H2O within the MOF framework could guide the modification via rational design with improved performance under real-world conditions.

Effective treatment of thioantimonates-bearing waters by nanocrystalline iowaite, an iron-based layered double hydroxide.

Elevated concentrations of antimony (Sb) in the environment originating from natural and anthropogenic sources are of global concern due to their high toxicity and mobility. Notably, the formation of thioantimony species (e.g. tri- and tetra-thioantimonates) enhances Sb release into aquatic systems, and they may dominate Sb species in reducing environments, such as sulfidic geothermal waters. In this study, batch sorption experiments were conducted to investigate thioantimonates removal from aqueous solution by nanocrystalline iowaite, a sorbent suitable for incorporating hazardous anions but not used for treating thioantimonates-bearing waters up to now. Based on the fits of kinetics and isotherm sorption models as well as the structural comparison of iowaite before and after its reaction with thioantimonates-bearing solutions by use of XRD and XPS analyses, both the anion exchange between thioantimonates in solution and chloride in the interlayer regions of iowaite and the inner-sphere complexation of sorbed thioantimonates with iron atoms located in iowaite layers were found to be responsible for the efficient removal of aqueous thioantimonates by iowaite. Moreover, the presence of common anions (SO42-, Cl-, and NO3-) or Sb oxyanions (antimonite and antimonate) over a wide range of concentrations had little effect on thioantimonates sorption, whereas the addition of arsenic oxyanions (arsenite and arsenate) with high concentrations exhibited a clear inhibition of thioantimonates removal. Nevertheless, iowaite is still a strong scavenger of thioantimonates under environmentally relevant conditions and therefore holds promise for future large-scale treatment of geothermal waters, anoxic groundwaters, and mining wastewaters that are potentially rich in thioantimonates.

Retention of Nickel and Cobalt in Boda Claystone Formation

The Boda Claystone Formation (BCF) is considered to serve as a natural barrier to the potential high-level radioactive waste repository in Hungary. In order to evaluate the radionuclide retention capacity of the albitic claystone of the BCF, the adsorption and diffusion properties of the rock for Ni2+ and Co2+ cations (activation products) were investigated separately and in competitive conditions when the two ions were simultaneously added. Batch sorption experiments were performed with powdered and conditioned albitic claystone samples in synthetic pore water to obtain adsorption isotherms. In addition, adsorption tests were performed on petrographic thin sections to check the transferability between dispersed and compact systems. Correlation analysis of microscopic X-ray fluorescence elemental maps recorded on thin sections suggested that nickel is primarily bound to clay minerals (mainly illite and chlorite), which was confirmed by (scanning) transmission electron microscopy measurements. Around illite particles, a newly formed nickel-rich few atomic layer thick phyllosilicate phase was identified. The discrepancy between the experimental and modeled adsorption isotherm at high concentrations could be explained with this nickel-rich new phase. Apart from Cin = 10−3 M and only Ni2+ or Co2+ in the source, the apparent diffusion coefficients of Ni2+ and Co2+ (Cin = 10−3–10−2 M) were found to be similar. Overall, the BCF shows promising capabilities to retain the studied radionuclides.

Tuning Metal-Organic Framework Linker Chemistry for Transition Metal Ion Separations.

The pressing demand for critical metals necessitates the development of advanced ion separation technologies for circular resource economies. To separate transition metal ions, which exhibit near-identical chemical properties, adsorbents and membranes must be designed with ultraselective chemistries. We leverage the customizability of metal-organic frameworks (MOFs) to systematically study the role of material chemistry in sorption and selectivity of Co2+, Ni2+, and Cu2+. To isolate the effect of MOF linker chemistry, a series of functionalized UiO-66 derivatives was synthesized from the same parent MOF through solvent-assisted linker exchange, which produced >70% linker conversion for nine linker functional groups. This work presents the first instance of post-synthetic incorporation of carboxylic acid groups in UiO-66, which was achieved with >90% conversion. A technique was developed for in situ MOF deposition in a quartz crystal microbalance to precisely monitor real-time sorption of Co2+, Ni2+, and Cu2+ in UiO-66-X [where X = H, (OH)2, COOH, or (COOH)2] and validated by comparing to batch sorption experiments (5 mM, pH 5). Carboxylic acid-functionalized derivatives exhibited the highest uptake and a trend of Cu2+ > Co2+ > Ni2+, with the highest sorption of 5.5% (g Cu2+/g MOF), equivalent to 37% mol Cu2+/mol linker, occurring in UiO-66-(COOH)2. Binary salt and single salt batch sorption experiments demonstrated preferential copper binding in all studied MOFs and selectivity enhancement in binary salt conditions. UiO-66-(COOH)2 exhibited the highest selectivity of 14 for equimolar Cu2+/Ni2+ and 13 for Cu2+/Co2+. Density functional theory calculations of ion binding energy at UiO-66-X pore windows indicate higher copper affinity for all functional groups and a trend in binding energy of UiO-66-(COOH)2 > UiO-66-COOH > UiO-66-(OH)2 > UiO-66-H for each transition metal ion, in good agreement with experimental results. This work highlights the effectiveness of post-synthetic modification for tuning nanostructured materials to achieve similar ion separations.

Towards a better understanding of sorption of persistent and mobile contaminants to activated carbon: Applying data analysis techniques with experimental datasets of limited size.

The complex sorption mechanisms of carbon adsorbents for the diverse group of persistent, mobile, and potentially toxic contaminants (PMs or PMTs) present significant challenges in understanding and predicting adsorption behavior. While the development of quantitative predictive tools for adsorbent design often relies on extensive training data, there is a notable lack of experimental sorption data for PMs accompanied by detailed sorbent characterization. Rather than focusing on predictive tool development, this study aims to elucidate the underlying mechanisms of sorption by applying data analysis methods to a high-quality dataset. This dataset includes more than 60 isotherms for 22 PM candidates and well-characterized high-surface-area activated carbon (AC) materials. We demonstrate how tools such as distance correlation and clustering can be used effectively to identify the key parameters driving the sorption process. Using these approaches, we found that aromaticity, followed by hydrophobicity, are key sorbate descriptors for sorption, overshadowing steric and charge effects for a given sorbent. Aromatic PMs, although classified as mobile contaminants based on their sorption to soil, are well adsorbed by AC as engineered adsorbent via π-π interactions. Non-aromatic and especially anionic compounds show much greater variability in sorption. The influence of ionic strength and natural organic matter on adsorption was considered. Our approach will help in the analysis of solute-sorption systems and in the development of new adsorbents beyond the specific examples presented here. In order to make the approach accessible, the code is freely available and described on GitHub (https://github.com/Laura-Lotteraner/PM-Sorption), following the FAIR data principles.

Modeling of an adsorption study of a synthesized hematite composite for the removal of lead and cadmium from contaminated water

The use of enormous nanomaterials with enhanced functionality, and improved structural morphology is thought of this era for water pollution treatment. Loaded nanomaterials using different low-cost and wasted biomass could be synthesized for efficient functional properties. .Nanostructures with different structures and morphology have been prepared with efficiency to handle single and multi-component aqueous solutions. Iron oxide-loaded rice husk biochar, named hematite nanomaterial (HLRHBC) was used for lead and cadmium removal and its surface removal capacity was compared with raw rice husk (RH) and rice husk biochar (RHBC) adsorbents. Biochar was obtained by pre-pyrolysis at 400-500 °C and nanocomposite was then prepared by loading on biochar surface. The 89.45% removal efficiency was obtained for lead remediation by nanomaterial and 89.3%, and 88.3% by rice husk biochar and raw form of rice husk respectively. For cadmium adsorption 73.4%, 70.6% and 54.76% were removal efficiency for nanomaterials, rice husk biochar, and rice husk respectively. Isothermal calculations were applied to experimental data and it revealed favorable adsorption results by Freundlich, Dubinin–Radushkevich, and Temkin isotherms as indicated by their R 2 values approaching near 1, efficient adsorption capacity values and constant calculations within favorable approach revealed nanomaterial suitable for adsorption purposes. Error analysis favored nanomaterial adsorption results by limiting value to small error results. Kinetic calculations revealed maximum Qe (mg/g) value 22.57 ± 0.013 mg/g in case of lead adsorption and 22.93 ± 0.013 mg/g for cadmium adsorption HLRHBC. Kinetic and thermodynamic calculations proved spontaneous physicochemical sorption experiments. Desorption experiments separated metal and adsorbent for recovery and reuse of nanomaterial. Hematite biomass composite was found efficient and novel sorbent for lead and cadmium uptake and recovery.

Fluorierte Squareimine zur molekularen Trennung von aromatischen und aliphatischen Verbindungen

AbstractDie Entwicklung energieeffizienterer Trenntechnologien ist von entscheidender Bedeutung. Insbesondere die Trennung von cyclischen aliphatischen Kohlenwasserstoffen von ihren aromatischen Gegenstücken bleibt aufgrund der Bildung von Azeotropen und ähnlicher physikalischer Eigenschaften eine große Herausforderung, die oft energieintensive Prozesse erfordert. Hier stellen wir eine neue Klasse von elektronenarmen Makrocyclen mit einer einzigartigen rechteckigen Struktur vor, um Interaktionen innerhalb der Poren zu optimieren, wodurch eine hochselektive molekulare Abtrennung aromatischer Verbindungen aus diesen Mischungen ermöglicht wird. Durch die Nutzung dynamisch‐kovalenter Iminchemie wird das auf Squareimin NDI2F42‐basierende kristalline Material direkt in hoher Ausbeute (83 %) aus der Reaktionsmischung erhalten. Analog wird das größere Kongener NDI2F82 mit einer Ausbeute von 69 % gewonnen. In Dampfsorptions‐ und Diffusionsexperimenten zeigt NDI2F42 schnelle Adsorptionskinetiken mit einer Selektivität von 97 : 3 für Benzol gegenüber Cyclohexan und 93 : 7 für Toluol gegenüber Methylcyclohexan, während Röntgenstrukturanalysen an Einzelkristallen und Pulvern darauf hindeuten, dass die Selektivität hauptsächlich durch gerichtete Wechselwirkungen zwischen den elektronenarmen Paneelen und den aromatischen Gästen bestimmt wird.

Fluorinated Squareimines for Molecular Sieving of Aromatic over Aliphatic Compounds.

The development of more energy-efficient separation technologies is essential. Especially the separation of cyclic aliphatic hydrocarbons from their aromatic counterparts remains a significant challenge due to azeotrope formation and similar physical properties, often requiring energy-intensive processes. Herein, we introduce a novel class of electron-deficient macrocycles with a unique rectangular structure to optimise interactions within the pore, enabling the highly selective molecular sieving of aromatic compounds from mixtures. Utilising dynamic covalent imine chemistry, the squareimine NDI2F42-based crystalline functional material is directly obtained from the reaction mixture in a single self-assembly step in high yields of 83 %, alongside the larger NDI2F82 congener, which can be obtained in 69 % yield. In vapour sorption and diffusion experiments, NDI2F42 demonstrates rapid adsorption kinetics with selectivities of 97 : 3 for benzene over cyclohexane and 93 : 7 for toluene over methylcyclohexane, while single-crystal and powder X-ray diffraction studies indicate that the selectivity is primarily governed by directed interactions between the electron-deficient panels and aromatic guests.

Performance Analysis of Effective Methylene Blue Immobilization by Carbon Microspheres Obtained from Hydrothermally Processed Fructose

Carbon microspheres have been synthesized by the hydrothermal method with fructose and a phosphoric acid solution at two different concentrations, which were used as precursors. The obtained materials were characterized by elemental analysis, X-ray powder diffraction (XRPD) analysis, scanning electron microscopy (SEM), nitrogen adsorption/desorption measurements, and Fourier transform infrared (FTIR) spectroscopy. Batch sorption experiments were performed to remove methylene blue (MB) from aqueous solutions by varying the initial concentration of MB (C0) from 50 to 500 mg/dm3, contact period, solution pH value, and temperature. Prepared sorbents consisted of microsphere particles with diameters in the range of 0.6–2.7 µm. The synthetic route was found to govern the microporous–mesoporous structure and surface acidic functional groups of the final product. A phosphoric acid concentration of 40 wt.% gave carbon material with a specific surface area of 932 m2/g and a total pore volume of 0.43 cm3/g. It was found that the extent of MB sorption by the obtained carbon microspheres increased with initial dye concentration, contact time, and especially solution pH but slightly decreased with increasing temperature. Kinetic studies showed that the dye sorption process followed pseudo-second-order kinetics.

Comparative Study of Water and Milk Kefir Grains as Biopolymeric Adsorbents for Copper(II) and Arsenic(V) Removal from Aqueous Solutions.

This study investigates the biosorption capabilities of kefir grains, a polysaccharide-based byproduct of the fermentation process, for removing copper(II) and arsenic(V) from contaminated water. Unlike traditional heavy-metal removal methods, which are typically expensive and involve environmentally harmful chemicals, biopolymeric materials such as kefir grains provide a sustainable and cost-effective alternative for adsorbing hazardous inorganic pollutants from aqueous solutions. Our experimental results revealed significant differences in the sorption capacities of two types of kefir grains. Grains of milk kefir outperformed water kefir, particularly in copper(II) removal, achieving up to 95% efficiency at low copper concentrations (0.16 mmol·L-1) and demonstrating a maximum sorption capacity of 49 µmol·g-1. In contrast, water kefir grains achieved only 35.5% maximum removal efficiency and exhibited lower sorption capacity. For arsenic(V) removal, milk kefir grains also showed superior performance, removing up to 56% of arsenic in diluted solution with experimental sorption capacities reaching up to 20 µmol·g-1, whereas water kefir grains achieved a maximum removal efficiency of 34.5%. However, these findings also suggest that while kefir grains show potential as low-cost biosorbents, further modifications are needed to enhance their competitiveness for large-scale water treatment applications.

Electrochemical Formation of Layered Organo-MnO2 and Its Application to Selective Iodide Recovery

We have fabricated a thin film of multilayered MnO2 whose interlayer is occupied with cetyltrimethylammonium cations (CTA+), using a simple anodic approach. X-ray diffraction (XRD) analysis and Fourier-transform infrared spectroscopy (FTIR) revealed that the deposited film possesses a layered structure of MnO2 and CTA molecules. The obtained film, CTA-intercalated layered MnO2 (CTA/MnO2), was applied as a sorbent toward iodide (I–). CTA/MnO2 film did not show significant iodide sorption from artificial seawater solution containing 0.1 mM NaI, but effectively sorbed iodide anions by excluding Ca2+ and HCO3 – from the artificial seawater solution, even in the presence of large amount of Cl– and SO4 2– anions. This indicates that Ca2+ and/or HCO3 – inhibit the uptake of iodide ions into the interlayer of CTA/MnO2. The sorption isotherm was in good agreement with the Langmuir type, and the maximum sorption capacity was estimated to be 213 mg/g-MnO2. Sorption of iodides into the interlayer of MnO2 film was evidenced by X-ray photoelectron spectroscopy (XPS). The results suggest that the sorption of iodide by the CTA/MnO2 film occur via not only simple ion-exchange, but also hydrophobic interaction between the interlayer organic phase of the film and iodide ions in solution. The layered structure of the CTA/MnO2 composite remained unchanged after the sorption experiment. Figure 1

Hydrophobic cordierite-based capillary membranes applied to desalination

Hydrophobic ceramic membranes are widely used in water treatment, increasingly in desalination using membrane distillation process. Indeed, due to their ability to perform in harsh pH, temperature, and pressure conditions, they may replace hydrophobic polymer membranes. Many examples exist in the literature using porous ceramic membranes in a tubular configuration; however, a few of them reports on capillary porous membranes that may be further applied to desalination by membrane distillation. The development of membrane supports based on low cost powders instead of more expensive alumina, titania or other oxides will help decrease the production cost of porous capillary membranes. Novel cordierite capillary membrane supports were fabricated by extrusion using various cost efficient and bio-sourced pore-forming agents such as corn starch, maize flour, and rice husk. The capillary supports were further coated with one to three filtration layers, namely zirconia (8 m2/g), zirconia (43 m2/g), and γ-alumina to yield membranes with an active layer pore size of 9 nm. The different membranes were finally chemically modified using three alkoxysilanes, namely 1H,1H,2H,2H-perfluorooctyltriethoxysilane, 1H,1H,2H,2H-perfluorodecyltriethoxysilane and dodecyltriethoxysilane to bring hydrophobicity to the membranes to be applied to air gap membrane distillation (AGMD). The chemical modification of the mineral capillary membranes was evidenced by infrared spectroscopy, water contact angle measurement, and N2 and water vapors sorption experiments. Thermogravimetric and gas sorption analyses allowed us to approximate the number of grafted molecules and their temperature resistance. The pure water permeability of the hydrophilic non-modified corn starch-based membrane was 597 L/(m2.h.bar) that was higher than the membranes prepared with maize flour (143 L/(m2.h.bar)) and rice husk (302 L/(m2.h.bar)). AGMD of a NaCl solution (35 g/L) yielded a permeate flux between 3–8 L/(m2.h). The membranes grafted with 1H,1H,2H,2H-perfluorodecyltriethoxysilane gave a higher rejection of 95 % due to higher contact angle and Liquid Entry Pressure of water (LEPw).

Engineered Mg-modified biochar-based sorbent for arsenic separation and pre-concentration

The utilization of biochar as a relatively efficient sorbent or stationary phase for the separation and preconcentration of a wide range of analytes represents an innovative approach in current sample pretreatment methods. Appropriate pre- and post-pyrolysis modification of the input precursor and pyrolysis product, respectively, allows targeted design of the physicochemical properties and sorption characteristics of the resulting sorbent. The present work deals with the preparation of pyrolysis materials based on unmodified cattail leaf biomass (BC) and its Mg-modified analogue (MgBC) by a slow pyrolysis process at 500 °C and a residence time of 1 h in a pyrolysis reactor. Physicochemical characterization of BC and MgBC carried out by pH, total C, N, surface size analysis (SSA), 13C NMR, SEM-EDX and XRD confirmed significant morphological and mineralogical differences between the prepared sorbents. By performing sorption experiments using a model anionic analyte (As) and application of Langmuir isotherm, we found that the predicted maximum sorption capacity of MgBC for As is 13.5-fold higher than that of BC. The sorption process of As by both sorbents is best described by the Sips adsorption isotherm (R2 ≥ 0.995) and a pseudo-nth order kinetic model (R2 ≥ 0.997). The optimum pH for As sorption by BC and MgBC sorbents is in the interval 5–6. The presence of competitive phosphate anions (equimolar concentration of 1:1) in the solution significantly reduces the sorption capacity of MgBC for As by 40% for BC by 70%. The presence of Cl- ions showed no significant effect on the sorption capacity of Bc and MgBC for As. Both sorbents were best recovered using 0.1 mol/L NaOH solution when the desorption efficiency for both sorbents was more than 95%. The MgBC sorbent showed 35% retention of As from the real sample in the model SPE column at a flow rate of 0.12 mL/s. Based on the obtained knowledge, it is evident that biochar-based sorbent prepared from Mg-modified precursor represents an effective sorbent for anionic forms of analytes and opens the possibility of its use also in preconcentration and separation techniques.

Efficient Selective CO2 Composite Sorbent from Amino Acid Ionic Liquids and Silica Gel: 2H NMR Spectroscopy Provides Insight on the CO2-Binding Mechanism and in-Pore Microscopic Viscosity.

A promising CO2 sorbent based on the [Emim][Gly] (1-ethyl-3-methylimidazolium glycinate)/silica gel composite has been studied. CO2 sorption experiments have shown that the optimum loading of [Emim][Gly] ionic liquid in silica gel is 40 wt.%. The 2-step process CO2 binding mechanism in [Emim][Gly] has been proposed based on the results of sorption experiments, 2H NMR spectroscopy and ab-initio calculations. The impact of CO2 on the microscopic viscosity and the dynamical melting of ionic liquid has been thoroughly investigated. 2H NMR spectroscopy has revealed that CO2 strongly binds cation and anion in [Emim][Gly], forcing them to move in a correlated fashion.

Photoaging effects on polyethylene microplastics: Structural changes and chlorpyrifos adsorption

Microplastics (MP) are a global concern due to their small size, insolubility in water, and non-degradable nature, and long-term environmental persistence. Weathering processes, such as ultraviolet (UV) radiation, can alter their properties, enhancing their ability to absorb pollutants or release harmful substances, such as pesticides, which is also an environmental concern, thereby complicating their environmental impact and mitigation efforts. This study investigates the impact of UVB-induced photoaging on polyethylene (PE) microplastics and their sorption behavior towards the pesticide chlorpyrifos (CP). PE microplastics were exposed to varying UVB aging durations, leading to significant changes in their physicochemical and morphological properties. The sorption experiments revealed that aged microplastics exhibited increased affinity for CP, with adsorption capacity rising by 17.9% compared to pristine PE. This enhanced adsorption was attributed to the (1) introduction of oxygen-containing functional groups, facilitating the formation of hydrogen bonds between the microplastic surface and surrounding water molecules, thereby contributing to the adsorption of CP; (2) formation of irregular micropores and surface roughness, potentially providing ample sites for pesticide adsorption and (3) reduction in crystallinity from 35% to 30%, which favors the sorption of hydrophobic organic pollutants. Density Functional Theory (DFT) calculations supported these findings by showing changes in the electronic structure of PE that facilitate interactions with CP. These results provide critical insights into the environmental behavior of aged microplastics and their potential to adsorb hazardous chemicals, underscoring the need for further research on the environmental impact of microplastic aging.

Nanosized SiO2-enhanced PDMS membrane for efficient isopropanol–butanol–ethanol (IBE) separation by pervaporation

Pervaporation separation of isopropanol–butanol–ethanol (IBE) aqueous mixture was carried out using polydimethylsiloxane (PMDS) membranes containing 5, 10, and 15 wt.% of nanosized SiO2. PDMS/SiO2 membranes prepared by solution-casting technique were characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and field emission scanning electron microscopy (FESEM). Sorption experiments were performed at 30 °C, 40 °C, and 50 °C, and the interaction parameters between the pure components and the membrane were calculated. Further, the activity coefficients, excess Gibbs energies, and binary interaction parameters of organic-water binary systems at different temperatures were estimated using the UNIFAC method. A single-component permeation through pristine PDMS and nanocomposite PDMS membranes, as well as the pervaporation separation performance of PDMS-based membranes at different temperatures for a model IBE mixture with a concentration of 20 g·L−1, were investigated. The pervaporation results showed that the highest butanol permeability (15514 Barrer) and selectivity (102.6) values were obtained for 5 wt.% and 15 wt.% SiO2-filled PDMS membranes at 30 °C, respectively.

Silica-Based Composite Sorbents for Heavy Metal Ions Removal from Aqueous Solutions.

Weak polyelectrolyte chains are versatile polymeric materials due to the large number of functional groups that can be used in different environmental applications. Herein, one weak polycation (polyethyleneimine, PEI) and two polyanions (poly(acrylic acid), PAA, and poly(sodium methacrylate), PMAA) were directly deposited through precipitation of an inter-polyelectrolyte coacervate onto the silica surface (IS), followed by glutaraldehyde (GA) crosslinking and extraction of polyanions chains. Four core-shell composites based on silica were synthesized and tested for adsorption of lead (Pb2+) and nickel (Ni2+) as model pollutants in batch sorption experiments on the laboratory scale. The sorbed/desorbed amounts depended on the crosslinking degree of the composite shell, as well as on the type of anionic polyelectrolyte. After multiple loading/release cycles of the heavy metal ions, the maximum sorption capacities were situated between 5-10 mg Pb2+/g composite and 1-6 mg Ni2+/g composite. The strong crosslinked composites (r = 1.0) exhibited higher amounts of heavy metal ions (Me2+) sorbed than the less crosslinked ones, with less PEI on the surface but with more flexible chains being more efficient than more PEI with less flexible chains. Core-shell composites based on silica and weak polyelectrolytes could act as sorbent materials, which may be used in water or wastewater treatment.

Multi-decadal impacts of effluent loading on phosphorus sorption capacity in a restored wetland

Natural wetlands are widely used and cost-effective systems for the passive remediation of phosphorus (P)-rich surface waters from various effluent sources. Yet the long-term biogeochemical impacts of effluent loading on wetland P retention capacity are unclear. Here, we had a unique opportunity to document the spatio-temporal evolution of sediment P sorption over a ∼25-year period of constant municipal and industrial effluent loading, as part of a wetland restoration and wastewater treatment strategy in one of the largest restored wetlands in Canada. Sediment P sorption experiments across Frank Lake's three basins revealed a wide spatial variation in sorption capacity, closely linked to sediment geochemistry gradients (Ca, Fe, and Mn). Relative to a similar study ∼25 years prior, P sorption capacity has become exhausted near the effluent inlet, but remarkably, remains elevated throughout the rest of the wetland. Compared to other prairie wetlands and global aquatic ecosystems, Frank Lake has a greater capacity overall to retain P through sediment sorption. Given the paucity of long-term (multi-decade) data on wetland response to effluent loading, we provide key insights into the dynamics of wetland P cycling in human-dominated watersheds.

Study on the sorption and desorption behavior of La3+ and Bi3+ by bis(2-ethylhexyl)phosphate modified activated carbon.

The separation of 213Bi from its parent radionuclide 225Ac via radionuclide generators has proven to be a challenge due to the limited performance of the current sorbents. This study evaluated the separation performance of La3+ (as a surrogate for 225Ac) and Bi3+ using bis(2-ethylhexyl)phosphate monofunctionalized activated carbon (HDEHP/AC). The potential applications of phosphate groups as active sites and the carbon structure as a sorbent support were confirmed and validated. Various factors, including pH values, salt concentration, halide ions, contact time, solid-to-liquid ratio, initial La3+/Bi3+ concentration, and gamma irradiation were examined through batch sorption experiments in both single and binary systems. HDEHP/AC had a high sorption capacity for La3+ via electrostatic attraction, with the sorption data fitting well to the pseudo-second-order kinetic equation and Langmuir model. The sorption performance of La3+ on HDEHP/AC was minimally affected as the NaCl/NaI concentrations increased at pH = 2, whereas the sorption capacity for Bi3+ decreased significantly. Additionally, selective desorption of La3+ and Bi3+ was achieved using HNO3 and NaI solutions, respectively. These results backed up by a conceptual separation process point toward a potential use of these materials in a direct/inverse 225Ac/213Bi radionuclide generator. Further optimization of the material and separation process will be required to bring this class of promising materials into an actual generator for medical applications.