Effective Separation Research Articles

Building Asymmetric Zn−N3 Bridge between 2D Photocatalyst and Co‐catalyst for Directed Charge Transfer toward Efficient H2O2 Synthesis

AbstractTwo‐dimensional (2D) polymeric semiconductors are a class of promising photocatalysts; however, it remains challenging to facilitate their interlayer charge transfer for suppressed in‐plane charge recombination and thus improved quantum efficiency. Although some strategies, such as π–π stacking and van der Waals interaction, have been developed so far, directed interlayer charge transfer still cannot be achieved. Herein, we report a strategy of forming asymmetric Zn−N3 units that can bridge nitrogen (N)‐doped carbon layers with polymeric carbon nitride nanosheets (C3N4−Zn−N(C)) to address this challenge. The symmetry‐breaking Zn−N3 moiety, which has an asymmetric local charge distribution, enables directed interfacial charge transfer between the C3N4 photocatalyst and the N‐doped carbon co‐catalyst. As evidenced by femtosecond transient absorption spectroscopy, charge separation can be significantly enhanced by the interfacial asymmetric Zn−N3 bonding bridges. As a result, the designed C3N4−Zn−N(C) catalyst exhibits dramatically enhanced H2O2 photosynthesis activity, outperforming most of the reported C3N4‐based catalysts. This work highlights the importance of tailoring interfacial chemical bonding channels in polymeric photocatalysts at the molecular level to achieve effective spatial charge separation.

Indium Oxide Layer Dual Functional Modified Bismuth Vanadate Photoanode Promotes Photoelectrochemical Oxidation of Water to Hydrogen Peroxide.

The photoelectrochemical (PEC) dual-electron pathway for water oxidation to produce hydrogen peroxide (H2O2) shows promising prospects. However, the dominance of the four-electron pathway leading to O2 evolution competes with this reaction, severely limiting the efficiency of H2O2 production. Here, we report a In2O3 passivator-coated BiVO4 (BVO) photoanode, which effectively enhances the selectivity and yield of H2O2 production via PEC water oxidation. Based on XPS spectra and DFT calculations, a heterojunction is formed between In2O3 and BVO, promoting the effective separation of interface and surface charges. More importantly, Mott-Schottky analysis and open-circuit potential measurements demonstrate that the In2O3 passivation layer on the BVO photoanode shifts the hole quasi-Fermi level towards the anodic direction, enhancing the oxidation level of holes. Additionally, the widening of the depletion layer and the flattening of the band bending on the In2O3-coated BVO photoanode favor the generation of H2O2 while suppressing the competitive O2 evolution reaction. In addition, the coating of In2O3 can also inhibit the decomposition of H2O2 and improve the stability of the photoanode. This work provides new perspectives on regulating PEC two/four-electron transfer for selective H2O2 production via water oxidation.

In situ isotropic 3D imaging of vasculature perfusion specimens using x-ray microscopic dual-energy CT.

Ex vivo x-ray angiography provides high-resolution, three-dimensional information on vascular phenotypes down to the level of capillaries. Sample preparation for ex vivo angiography starts with the removal of blood from the vascular system, followed by perfusion with an x-ray dense contrast agent mixed with a carrier such as gelatine or a polymer. Subsequently, the vascular micro-architecture of harvested organs is imaged in the intact fixed organ. In the present study, we present novel microscopic dual-energy CT (microDECT) imaging protocols that allow to visualise and analyse microvasculature in situ with reference to the morphology of hard and soft tissue. We show that the spectral contrast of µAngiofil and Micropaque barium sulphate in perfused specimens allows for the effective separation of vasculature from mineralised skeletal tissues. Furthermore, we demonstrate the counterstaining of perfused specimens using established x-ray dense contrast agents to depict blood vessels together with the morphology of soft tissue. Phosphotungstic acid (PTA) is used as a counterstain that shows excellent spectral contrast in both µAngiofil and Micropaque barium sulphate-perfused specimens. A novel Sorensen-buffered PTA protocol is introduced as a counterstain for µAngiofil specimens, as the polyurethane polymer is susceptible to artefacts when using conventional staining solutions. Finally, we demonstrate that counterstained samples can be automatically processed into three separate image channels (skeletal tissue, vasculature and stained soft tissue), which offers multiple new options for data analysis. The presented microDECT workflows are suited as tools to screen and quantify microvasculature and can be implemented in various correlative imaging pipelines to target regions of interest for downstream light microscopic investigation.

Synchronous photocatalytic benzimidazole formation and olefin reduction by magnetic separable visible-light-driven Pd-g-C3N4-Vanillin@γ-Fe2O3-TiO2 Nanocomposite.

A visible light-responsive magnetically separable photocatalyst Pd-g-C3N4-Vanillin@γ-Fe2O3-TiO2 is fabricated using vanillin as a natural junction under ultrasonic agitation. Structural, morphological, optical, thermal, and magnetic assessments of the as-prepared catalyst are carried out. The photocatalyst successfully drives the simultaneous benzimidazole formation, and olefin hydrogenation with high atom economy under blue LED light and mild conditions. The photocatalytic activity of Pd-g-C3N4-Vanillin@γ-Fe2O3-TiO2 is significantly affected by the γ-Fe2O3:TiO2 weight ratio. PL spectra revealed the effective separation of carriers in the fabricated catalyst promoting its photocatalytic activity. The action spectra using the apparent quantum efficiency (AQE) exhibited the maximum AQEs at 520 and 750nm in which the highest performance for styrene hydrogenation is observed. The title magnetically separable heterogeneous photocatalyst provides high yields of products under perfectly safe visible light, produces low/zero waste, and avoids using an external high-pressure hydrogen gas source, harmful solvents, undesirable additives, and reducing agents rendering green conditions for chemical reactions.

Separation of Lung Cancer Cells From Mixed Cell Samples Using Aptamer-Modified Magnetic Beads and Permalloy Micromagnets.

This study involved the design and fabrication of a microfluidic chip integrated with permalloy micromagnets. The device was used with aptamer-modified magnetic beads (MBs) of various sizes to successfully separate lung cancer cells from a mixture of other cells. The overall separation efficiency was evaluated based on the ratios of cells in the different outlets and inlets of the chip. The results showed efficiencies ranging from 43.4% to 50.2% for MB sizes between 1.36 and 4.50 µm. Interestingly, efficiency slightly decreased as the size of the MBs increased, contrary to predictions. Further examination revealed that larger MBs exerted gravitational force on the cell-bound MBs at low flow rates, causing the targets to settle before reaching the main microchannel region. This was attributed to fluidic resistance caused by a size mismatch between the inlet tube and the microfluidic conduit. An increase in cell accumulation at the inlet was observed with larger MB sizes due to gravity. Therefore, the definition of effective separation efficiency was revised to exclude the effect of cell accumulation at the inlet. Effective separation efficiencies were found to be 71.6%, 76.4%, and 79.4% for MB sizes of 1.36, 3.00, and 4.50µm, respectively. The study concluded that larger MBs interacted more with the magnetic force, resulting in better separation. However, cells with smaller MBs were more likely to evade the magnetic force. The investigation provides valuable insights into isolating lung cancer cells using this method, with the potential for clinical application in cancer diagnosis and treatment.

Research on the Hierarchical Separation of Rare Earths and Lithium from Rare Earth Molten Salt Slag

Lithium is an important non-renewable resource, and the study of the tiered separation of rare earths and lithium from rare earth molten salt slag is an important approach to solving the current global resource shortage. This article adopts a sulfuric acid leaching process and a lithium-containing solution iron lithium extraction separation process to recover lithium from rare earth molten salt slag. The method systematically investigates the impact of sulfuric acid concentration, liquid-to-solid ratio, leaching temperature, leaching time, pH, P507 concentration, phase ratio, extraction temperature, and extraction time on the lithium extraction effect and iron lithium separation effect in rare earth molten salt slag. The results show that under the conditions of a sulfuric acid concentration of 0.9 mol/L, a liquid-to-solid ratio of 8:1 mL/g, a leaching temperature of 70 °C, a leaching time of 90 min, a pH of 0.9, a P507 concentration of 50%, a phase ratio of 5:3, an extraction temperature of 30 °C, and an extraction time of 20 min, the lithium leaching rate reaches 97.8%, and the separation of iron and lithium is fully achieved. This method can efficiently recover the valuable element lithium from rare earth molten salt slag, which is of great significance for the subsequent preparation of lithium products and the realization of a closed-loop production of rare earth alloys by molten salt electrolysis.

Hydrothermally synthesized Hierarchical Pom-Pom-like Gadolinium Modified Tungsten Oxide reinforced with rGO for annihilation of Acetylsalicylic Acid and Crystal Violet

Herein, novel hierarchical Gd@WO3 pom-pom-like microstructures have been prepared through the hydrothermal method and combined with RGO sheets (denoted as RGO/Gd@WO3). The synthesized materials, along with their analogs, were characterized through X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), Fourier transform infrared (FT-IR), Mott-Schottky, current-voltage (I-V), electrochemical impedance spectroscopy (EIS), and optical analyses. The unique morphology of pom-pom-like microstructures allowed better interaction with pollutant molecules. Rare earth element (Gd3+) ions act as trapping species for photo-generated electrons and prolong the life span of reactive oxygen species (ROS). The high conductivity and flexible nature of RGO sheets provided fast transport of active species and provided stability to the photocatalytic material. To test the photocatalytic efficiency of RGO/Gd@WO3, crystal violet (CV) and acetylsalicylic acid (ASA) were used as model pollutants. Under a mimetic light source, RGO/Gd@WO3 exhibited maximum photodegradation of 98.8% and 84% for CV and ASA within 120 min of irradiation, respectively. Photocurrent, Mott-Schottky, and EIS experiments proved the production, effective separation, and transmission of photo-active species in the presence of RGO/Gd@WO3 as compared to Gd@WO3 and WO3. Given the electrochemical testing and optical analysis, the photocatalytic mechanism is anticipated for the high photocatalytic activity of RGO/Gd@WO3. The novel RGO/Gd@WO3 photocatalyst proved to be a superior photocatalytic material for the photodegradation of organic pollutants.

Deep eutectic supramolecular polymers based HPLC stationary phase: Green synthesis strategy and promising application prospects

BackgroundDeep eutectic solvents (DESs) have been widely and significantly applied in various fields due to their outstanding features such as low cost, easy preparation and good biodegradability. As novel derivatives of DESs, deep eutectic supramolecular polymers (DESPs) combine the macroscopic state of DESs with the covalent interactions of supramolecular polymers, which also possess the properties of DESs as multifunctional materials. Therefore, DESPs are believed to be promising candidates for separation science. However, there are no studies on the application of DESPs as stationary phases for HPLC analysis. ResultsIn this work, a novel DESP based HPLC stationary phase (Poly(DES)@SiO2) was developed for the first time through a green synthesis method by using DES as the polymerization monomer as well as the reaction medium. The results manifest that this novel Poly(DES)@SiO2 column can well interact with analytes through various mechanisms, and realize selective separation of a wide range of structurally similar hydrophilic/hydrophobic substances. More importantly, the separation of hydrophobic analytes on the Poly(DES)@SiO2 column is less time-consuming with fewer organic eluent, although the column efficiency is slightly lower than that of commercial C18 column. Furthermore, the Poly(DES)@SiO2 column exhibits excellent mechanical stability and satisfactory separation repeatability for steroid hormones. Therefore, a reliable method was established for detecting steroid hormones in actual samples with the recoveries ranging from 94.56 % to 103.84 %, which can meet the detection needs of commonly seen steroid hormones in food and the environment. SignificanceIn summary, this work provides some valuable theoretical references for the synthesis of new DESP based stationary phases through a green and facile strategy, and meanwhile, verifies the feasibility of DESP for effective HPLC separations. In addition, the promising application prospect of DESP based stationary phases in the analysis of complex samples has also been demonstrated, expanding the potential application of DES in separation science.

G-C3N4 based Z-scheme photocatalysts for tetracycline degradation: A Comprehensive Review

Graphitic carbon nitride (g-C3N4) has garnered significant attention due to its low cost, ease of preparation, high chemical stability, and non-toxicity. Nevertheless, pristine g-C3N4 faces challenges in simultaneously achieving a broad absorption range, high stability, efficient charge separation, and strong redox capability, which hampers its practical applications. Recently, g-C3N4-based Z-scheme photocatalysts have emerged as research hotspots owing to their robust redox ability, effective charge carrier separation, and capacity to harness visible light for degradation of tetracyclines (TCs) in waters. This review delves into the fundamental photocatalysis, and application of g-C3N4-based Z-scheme photocatalysts for the degradation of TCs pollutants. The review concludes with final remarks and a concise discussion on the prospects of g-C3N4-based Z-scheme photocatalysts.

DES-driven sustainable dual valorization of lignocellulose into carbon dots and porous biochar for effective wastewater remediation

Deep eutectic solvents (DES) are renowned for their effectiveness in deconstructing lignocellulose and extracting lignin, yet the challenges lie in lignin condensation and the disposal of the DES remnants after pretreatment. To overcome these issues, this work proposed a holistic strategy utilizing deep eutectic solvent (DES)-driven lignocellulose deconstruction to upgrade lignocellulose into nitrogen-doped carbon dots (CDs) and iron-decorated porous carbons, serving as photocatalysts and adsorbents, respectively. These nitrogen-doped CDs via the choline chloride/FeCl3 DES pretreatment exhibited abundant nitrogen/oxygen functional groups, enhancing photocatalytic activities and facilitating effective charge separation and transfer. The photocatalytic efficiency of the CDs on dyes reached 97 % under acidic conditions primarily, and free radical quenching experiments indicated that singlet oxygen was the dominant oxidant species. Moreover, the adsorption capabilities of Fe-decorated porous carbons for Congo red reached 2432.3 mg·g−1, surpassing most existing carbon materials. The adsorption mechanism was due to a synergistic effect including physical adsorption, coordination, hydrogen bonding, electrostatic, and π-π interactions. This study proposed a synergetic conversion of DES and lignocellulose into functional carbon materials for wastewater remediation, which inspired the development of a green and cost-effective biorefinery.

Evaluation of titanium dioxide/catechol polyurethane composite for antimicrobial resistance and wastewater treatment

In this study, a novel approach for the environmentally conscious extraction of titanium dioxide from ilmenite ore while limiting the environmental impact and enhancing the advantage from an economic process. Leaching conditions were tested with different acids for effective separation of the TiO2 and were optimized concerning different experimental parameters. TiO2 and TiO2NPs were characterized using with different tools. Catechol polyurethane foam immobilized with TiO2NPs was prepared and its antimicrobial action was tested against Gram-negative bacterium E. coli, Gram-positive bacterium B. cereus, and fungus A. niger. CAT-PUF /TiO2NPs showed antimicrobial effect against E. coli, B. cereus, and A. niger with inhibition zones of 27 ± 0.14, 12 ± 0.14, and 22 ± 0.06 mm, respectively. Incorporating bioinformatics, this research contributes to the burgeoning field of nanotechnology-enabled antimicrobial materials, offering insights into the potential applications of CAT-PUF/TiO2NPs in combating microbial threats. Through bio-informatics tools, the potential toxicity of the synthesized nanoparticles was assessed, providing valuable insights into their safety profile and environmental impact. Furthermore, simulating the binding affinity between the nanoparticles and target biomolecules, such as cell membrane proteins or enzyme receptors, this aspect of the research sheds light on the mechanistic underpinnings of their antimicrobial efficacy.

A straightforward strategy to modulate ROS generation of AIE photosensitizers for type-I PDT

Type-I photodynamic therapy (PDT), valued for its reduced oxygen requirement, generates highly cytotoxic •OH radicals. However, conventional strategies for developing type-I photosensitizers (PSs) are complex and involve intricate organic synthesis. Herein, we present a novel strategy to alter the generation of reactive oxygen species (ROS) by simply manipulating the twisting degree of donor–acceptor (D−A) type aggregation-induced emission (AIE) PSs. Specifically, natural saturated fatty acids are employed to modulate the twisting state of AIE PSs, with higher doping ratios yielding more twisted structures and increased type-I ROS generation. In contrast, fatty acids with higher crystallinity promote planar structures and type-II ROS generation. Theoretical calculations suggest that AIE PSs with highly twisted structures lead to a prominent reduction in ΔEST and effective separation of electron−hole pairs, thereby favoring efficient intersystem crossing and charge transfer. The PDT system primarily driven by type-I ROS exhibits efficient bactericidal activity against clinically drug-resistant bacteria, which remarkably accelerates the recovery of bacteria-infected wounds in mice. This study demonstrates the first example of modulating ROS generation type by manipulating the twisting degree of D−A type AIE PSs, eliminating the need for intricate molecular design and organic synthesis. The proposed strategy opens up new avenues for advancing PDT applications.

Preparation and Application of Weak Cation Exchange Resin Based on Thiol Click Reaction.

Using poly(styrene-divinylbenzene) microspheres as stationary phase matrix and mercaptosuccinic acid as a modifier, a new weak cation exchange resin was synthesized by thiol click reaction. The conditions for thiol-chlorine click reaction and thiol-alkene click reaction were optimized. The surface morphology and chemical composition of the modified microspheres were characterized by scanning electron microscopy, Fourier-transform infrared spectroscopy, and an elemental analyzer. The stationary phase can achieve the separation of six common cations within 25min. A homemade weak cation chromatographic column was used to determine the impurities of Na+ and K+ and the content of tetramethylammonium ions in tetramethylammonium hydroxide samples. The method showed a good linear correlation in the range of 0.1-500.0mg/L with correlation coefficients of 0.9998-0.9999, and the limits of detection (signal-to-noise ratio ≥ 3) were 0.01-0.20mg/L. The intra-day relative standard deviations (RSDs) were in the range of 1.1%-4.4%, and the inter-day RSDs were in the range of 0.8%-14.8%. The spiked recoveries were in the range of 91.92%-119.86%. The results showed that the prepared stationary phase exhibited effective separation ability and good reproducibility, which was suitable for the analysis of the impurities of Na+, K+, and the content of tetramethylammonium in the tetramethylammonium reagents.

Facile fabrication of BiOI/ZIF-67 Z-scheme heterojunction photocatalyst for visible-light-driven tetracycline degradation

In this paper, a novel Z-scheme BiOI/ZIF-67 photocatalyst (BOI/ZIF) was successfully prepared using an in-situ growth method, and its effectiveness in degrading tetracycline (TC) under visible light was assessed. Using a range of characterization techniques, the crystal structure, elemental composition, microstructure and optical characteristics of the composite catalyst were examined. Simultaneously, a 30% mass ratio catalyst (BOI/ZIF-30) could remove 91% of TC under visible light, which was 41% and 28% greater than the degradation rates of BiOI and ZIF-67, respectively. These results demonstrated that BOI/ZIF exhibited strong photocatalytic activity and excellent stability. The results of the radical quenching experiment and electron spin resonance revealed that h+ and •O2− were the principal chemical substances responsible for TC degradation, corresponding with the suggested charge transfer mechanism of Z-scheme heterojunction. The Z-scheme heterojunction created between BiOI and ZIF-67 improved the effective separation of photogenerated carriers and boosted the efficiency of TC degradation. This study offers a promising method for designing photocatalytic systems to break down antimicrobial contaminants.

Green and Mild Fabrication of Magnetic Poly(trithiocyanuric acid) Polymers for Rapid and Selective Separation of Mercury(II) Ions in Aqueous Samples

The removal and detection of highly toxic mercury(II) ions (Hg2+) in water used daily is essential for human health and monitoring environmental pollution. Efficient porous organic polymers (POPs) can provide a strong adsorption capacity toward heavy metal ions, although the complex synthetic process and inconvenient phase separation steps limit their application. Hence, a combination of POPs and magnetic nanomaterials was proposed and a new magnetic porous organic polymer adsorbent was fabricated by a green and mild redox reaction in the aqueous phase with trithiocyanuric acid (TA) and its sodium salts acting as reductive monomers and iodine acting as an oxidant. In the preparation steps, no additional harmful organic solvent is required and the byproducts of sodium iodine are generally considered to be non-toxic. The resulting magnetic poly(trithiocyanuric acid) polymers (MPTAPs) are highly porous, have large surface areas, are rich in sulfhydryl groups and show easy magnetic separation ability. The experimental results show that MPTAPs exhibit good adsorption affinity toward Hg2+ with high selectivity, rapid adsorption kinetics (10 min), a large adsorption capacity (211 mg g−1) and wide adsorption applicability under various pH environments (pH 2~8). Additionally, MPTAPs can be reused for up to 10 cycles, and the magnetic separation step of MPTAPs is fast and convenient, reducing energy consumption compared to centrifugation and filtration steps required for non-magnetic adsorbents. These results demonstrate the promising capability of MPTAPs as superior adsorbents for effective adsorption and separation of Hg2+. Based on this, the prepared MPTAPs were adopted as magnetic solid-phase extraction (MSPE) materials for isolation of trace Hg2+ from aqueous samples. Under optimized conditions, the extraction and quantification of trace Hg2+ in water samples were accomplished using inductively coupled plasma mass spectrometry (ICP-MS) detection after MSPE procedures. The proposed MPTAPs-based MSPE-ICP-MS method is efficient, rapid, sensitive and selective for the determination of trace Hg2+, and was successfully employed for the accurate analysis of trace Hg2+ in tap water, wastewater, lake water and river water samples.

Boosted photogenerated carriers separation in FeP/Cu3P/ZnIn2S4 photocatalyst for highly efficient H2 evolution under visible light

The development of efficient photocatalysts with effective charge separation and numerous active sites is a key challenge in photocatalysis. ZnIn2S4 based binary and ternary composite photocatalysts were successfully synthesized using microwave hydrothermal and calcination techniques, exhibiting excellent hydrogen production capabilities. Among these, the FeP/Cu3P/ZnIn2S4 composite photocatalysts demonstrated the highest hydrogen production performance, with an average rate of 1.613 mmol g−1 h−1, which was 4.42 times greater than that of pure ZnIn2S4. The enhanced hydrogen production of the FeP/Cu3P/ZnIn2S4 photocatalysts was attributed to the establishment of a p-n heterojunction at the ZnIn2S4 interface. Furthermore, the presence of FeP lowered the hydrogen production barrier in the system and provided additional active sites for the catalytic reaction.

Nanoscale engineering of semiconductor photocatalysts boosting charge separation for solar-driven H2 production: Recent advances and future perspective

Abstract Photocatalytic hydrogen (H₂) production is regarded as an efficient method for generating renewable energy. Despite recent advancements in photocatalytic water splitting, the solar-to-hydrogen conversion efficiency of photocatalysts remains well below the 10% target needed for commercial viability due to ongoing scientific challenges. This review comprehensively analyzes recent advancements in nanoscale engineering of photocatalytic materials, emphasizing techniques to enhance photogenerated charge separation for efficient solar hydrogen production. Here we highlight the nanoscale engineering strategies for effective charge separation including crystal engineering, junction engineering, doping-induced charge separation, tailoring optoelectronic properties, hierarchical architecture, defects engineering, various types of heterojunctions, and polarity-induced charge separation, and discuss their unique properties including ferroelectric on spatial charge separation along with the fundamental principles of light-induced charge separation/transfer mechanisms, and the techniques for investigation. This study, critically assesses strategies for effective photogenerated charge separation to enhance photocatalytic hydrogen production and offers guidance for future research to design efficient energy materials for solar energy conversion.

Intracellular Gold Nanocluster/Organic Semiconductor Heterostructure for Enhancing Photosynthesis

AbstractPhotosynthetic microorganisms, which rely on light‐driven electron transfer, store solar energy in self‐energy carriers and convert it into bioenergy. Although these microorganisms can operate light‐induced charge separation with nearly 100 % quantum efficiency, their practical applications are inherently limited by the photosynthetic energy conversion efficiency. Artificial semiconductors can induce an electronic response to photoexcitation, providing additional excited electrons for natural photosynthesis to improve solar conversion efficiency. However, challenges remain in importing exogenous electrons across cell membranes. In this work, we have developed an engineered gold nanocluster/organic semiconductor heterostructure (AuNCs@OFTF) to couple the intracellular electron transport chain of living cyanobacteria. AuNCs@OFTF exhibits a prolonged excited state lifetime and effective charge separation. The internalized AuNCs@OFTF permits its photogenerated electrons to participate in the downstream of photosystem II and construct an oriented electronic highway, which enables a five‐fold increase in photocurrent in living cyanobacteria. Moreover, the binding events of AuNCs@OFTF established an abiotic‐biotic electronic interface at the thylakoid membrane to enhance electron flux and finally furnished nicotinamide adenine dinucleotide phosphate. Thus, AuNCs@OFTF can be exploited to spatiotemporally manipulate and enhance the solar conversion of living cyanobacteria in cells, providing an extended nanotechnology for re‐engineering photosynthetic pathways.

Dynamic CO2 separation performance of nano-sized CHA zeolites under multi-component gas mixtures

To identify and evaluate promising adsorbents for CO2 separation, we synthesized CHA zeolites with different cations (Na+, K+, Cs+) and crystal sizes (45 nm – CHA45 and 500 nm – CHA500), and evaluated their explored CO2 adsorption performance from CO2/N2/He and CO2/CH4/He mixtures. Grand Canonical Monte Carlo (GCMC) and molecular dynamics (MD) simulations predicted CO2, N2, and CH4 adsorption isotherms and CO2 mobilities, respectively, which were compared to experimental data. Breakthrough curve analysis was used to assess the CO2 dynamic adsorption performance. The breakthrough curve analysis shows the smaller crystal sizes (45 nm) enhance the CO2 separation due to shorter interacrystalline diffusion pathways. Notably, Cs-CHA45 removed 2.2 times more CO2 from CO2/N2/He than Cs-CHA500. K-CHA45 showed the highest CO2/N2 selectivity (108) and achieved 841mmol g−1 for CO2 capture from N2 and 721mmol g−1 for CO2 from CH4. These findings underscore the potential of CHA nanocrystals for effective CO2 separation in various applications.

Concurrent Estimation of Pregabalin and Etoricoxib by New Stability-Indicating RP-UPLC Approach - Application in Assay of Commercial Tablets

Background: The study emphasizes establishing a stability-indicating RP-UPLC method for concurrent estimation of pregabalin and etoricoxib in combined pharmaceutical formulations, confirming effective separation, sensitivity, and repeatability, validated according to ICH guidelines. Objective: The present research study aims to establish a new stability-indicating RP-UPLC method for concurrently estimating pregabalin and etoricoxib in blended powder and their combined tablet formulation with less run time, high sensitivity, and specificity. Methods: The effective separation of pregabalin and etoricoxib was achieved with HSS column C18 (150x2.1mm,1.8μm), 0.1% orthophosphoric acid:acetonitrile (65:35 v/v) at a flow rate of 0.3mL/min, and isocratic elution at 228nm. The elution of PRB and ETB was noticed at 1.56 and 2.01 minutes, with good resolution and system suitability with the developed approach. Results: Pregabalin and etoricoxib have shown linear responses from 18.75 to 112.5μg/mL and 15 to 90μg/mL, respectively. The range of the % RSD for intraday and inter-day precision was 0.33 to 0.81. The LOD and LOQ of pregabalin and etoricoxib were computed to be 0.07 μg/mL and 0.21 μg/mL, and 0.01μg/mL and 0.04 μg/mL, respectively, by standard deviation method. The validation method was carried out using ICH standards. The stability-indicating feature of the method was confirmed by the forced degradation studies where degradants generated by stress testing were clearly distinguished from the peaks of analytes. Conclusion: The shorter elution period and superior sensitivity of both analytes with this method have been found to be appropriate for regular analysis of pregabalin and etoricoxib.