Separation Column Research Articles

Preparation of chlorophyll compounds and simulation of DFT optical properties assisted screening of photosensitizers from Ginkgo biloba leaves

Chlorophyll compounds (Chls) from Ginkgo biloba leaves (GBL) are non-toxic natural pigments characterized by highly conjugated molecules and special spectra, making them ideally potential photosensitizers (PSs) in photodynamics therapy (PDT). In this study, 4 Chls were isolated from Ginkgo biloba polyprenols (GBPPs) wastes by using silica gel column separation and high performance liquid chromatography (HPLC). In addition, two new chlorophyll derivatives were successfully synthesized with chlorin e6 as the primary raw material. To evaluate and identify superior chlorophyll PSs, Density Functional Theory (DFT) and Density Functional Theory (TD-DFT)were employed to decode the microscopic and spectral properties of Ginkgo biloba Chls (GBChls). The spectral absorption, optical stability and reactive oxygen species (ROS) production of GBChls were further analyzed through comparisons of their frontier molecular orbital layout, charge distribution and excitation energy properties. Our results show that about 63 % absorption in the Q band for 14 GBChls comes from the π⇢π* transition from the highest occupied orbital (HOMO) to the lowest unoccupied orbital (LUMO), indicating the favorable delocalization effect of these GBChls. In particular, those GBChls with the long chain of the phytyl group exhibited higher total electron energy and thus could significantly increase the light stability. However, the large spatial volume and hydrophobicity of these compounds with the phytyl group chain was unfavorable for cellular uptake, leading to low ROS in cells. The electronegativity of porphin macrocycles in GBChls positively correlates with the intracellular ROS production rate, meaning that the former likely promotes the energy transfer between PSs and molecular oxygen during type II photoreaction. Among the GBChls, chlorin e6 demonstrated the highest ROS yields in DMF, while purpurin 18 compounds displayed long-wavelength absorption (698 nm), strong Q-band absorption, good optical stability, and high intracellular ROS production. Our findings highlight that chlorin e6 and purpurin 18 are most potential PSs anticancer drugs and offer new research perspectives for the processing and utilization of GBL resources.

Determination of quinclorac and quinclorac methyl ester in honey by online SPE-UPLC-MS/MS

A method employing online solid phase extraction (SPE) coupled to UPLC-MS/MS was developed for the determination of residues of the acid herbicide quinclorac plus its transformation product, quinclorac methyl ester, in honey. The analytical method involved dissolving the honey in a mixture of methanol:water followed by direct injection into a two-dimensional UPLC system which is used to perform an automated SPE cleanup on a reusable phenyl cartridge prior to the target analytes being transferred onto an analytical UPLC column for subsequent chromatographic separation followed by MS/MS detection. The limits of quantitation for quinclorac and quinclorac methyl ester in honey were both set at 0.5 µg kg−1 and the method detection limit was estimated to be 0.012 µg kg−1 for each compound. The working analytical range (0.5–100 µg kg−1) was validated by analysing a series of spiked replicate honey samples. The method was applied to the analysis of various honeys obtained from numerous different commercial sources. Quinclorac was detected in 9 out of 30 samples at concentrations ranging from 0.6 to 31.5 µg kg−1. Quinclorac methyl ester, which is estimated to be significantly more toxic than the parent herbicide itself, was not detected in any honey sample.

Robust nitrogen-rich covalent polymeric networks for ultra-efficient and selective palladium capture under harsh conditions

Selective capture of palladium (Pd) from high-level liquid waste (HLLW) is one of the frontier issues in materials science in order to alleviate the Pd resource scarcity and guarantee the safe disposal of radioactive wastes. However, this task remains a great challenge in HLLW treatment associated with low capacity, poor selectivity, and limited stability of materials in strongly acidic and radioactive environments. Here we conquer this challenge by designing covalent polymeric networks (CPNs) equipped with abundant bidentate (CPN-1) or tridentate (CPN-2) nitrogen-rich moieties as specific nano-traps for Pd(II). These CPNs are constructed through efficient and facile click reactions, among which CPN-1 bearing plentiful pyridinyl-triazolyl moieties sets a new record for Pd(II) uptake capacity (535 mg g−1), notably surpassing all the reported materials for Pd(II) separation from HNO3 solutions to date. Moreover, CPN-1 features additional attractive merits including good reusability, feasible dynamic column separation, outstanding Pd(II) selectivity over 17 coexisting cations, and excellent stability under highly acidic and radioactive conditions, making it highly promising for practical applications. This work provides a facile way to customize CPN adsorbents with superior performance and highlights the great potential of the prepared materials for metal capture applications.

Dynamics of large cavity induced by valve closure in an undulating pipeline

The dynamics of large cavity and the accompanied water column separation and rejoining induced by fast closing of a butterfly valve in an undulating pipeline system are investigated in this study. The three-dimensional computational fluid dynamics numerical simulations are performed using a newly developed interfacial surface tension-based model (ISTM) that accounts for the surface tension effect on large cavities. The applicability of the ISTM model is validated with the experimental data, showing better accuracy in predicting pressure fluctuations and cavity evolutions than three typical cavitation models. Differences in cavitation characteristics are observed between upstream and downstream of the valve. Upstream the valve, cavitation primarily appears at the pipe top, with the vapor volume fraction varying sharply due to the rarefaction pressure waves (maximum value of 0.0073). Downstream the valve, the complete water-column separation occurs, and vapor volume fraction changes slowly correspond with the growth and collapse of the large cavity (maximum value of 0.647). The maximum length of the large cavity can reach about six times the pipe diameter, with a minimum water vapor interface angle of 16°. The cavitation evolution displays a transition from a clustered inception to a sheet-like growth and collapse pattern. These findings contribute to the design and operation guidance for complex hydraulic systems during transient processes.

Experimental Investigation of Column Separation Using Rapid Closure of an Upstream Valve

In this study, the phenomenon of column separation that occurs in the downstream pipeline of a rapid closure valve is experimentally investigated. Special attention is paid to the dynamic behavior of the formation, growth, and collapse processes of cavities, which are observed using a high-speed camera. Synchronized images of cavity patterns and measured pressure histories are analyzed to elucidate the process of water column separation, the mechanism of column separation events, and the influence of parameters on the transient flow. Experimental results indicate that during the collapse process of vapor cavities, a superposition phenomenon involving a positive pressure wave and collapse wave occurs, resulting in a nearly three times rise of Joukowsky pressure. In all test cases, the maximum pressure of the pipeline exceeded 150 times the reservoir static pressure. A new classification for a water hammer combined with cavitation (four types of pressure oscillation patterns) is proposed based on whether the duration of column separation decreases sequentially and the maximum pipeline pressure follows the first collapse of cavities at the valve. As the initial flow velocity increases, there is generally an increase in maximum pressure; however, this trend may be scattered under certain operation conditions.

An all-glass based micro gas chromatographic column for light hydrocarbon separation with HKUST-1 as stationary phase

BackgroundThe gas chromatography column is one of the key components of the gas chromatograph and typically be miniaturized using micro-electro-mechanical system (MEMS) technology. Due to the limited area of the Si wafer, the column length of micro gas chromatographic column (μGCC) is usually much smaller than that of commercial chromatographic columns. Therefore, it is always difficult to use μGCCs to separate small molecule gas components such as light hydrocarbons. More importantly, the heterogeneous microchannel surface formed by silicon glass bonding causes uneven stationary phase coating, further preventing the improvement of separation performance. ResultsIn this paper, a novel all-glass based μGCC with 2 m length for the separation of light hydrocarbons is proposed. The microchannels of the μGCC were directly prepared in the glass substrate by ultrafast laser assisted chemical etching (ULAE). The all-glass microchannels make the coating of the hydrophilic metal-organic frameworks (MOFs) stationary phase continuously because of the homogeneous material composition. Therefore, a widely used copper based hydrophilic MOFs HKUST-1 was used as stationary phase for coating and testing. The test results show that the μGCC which is an open tubular column can realize the baseline separation of light hydrocarbons at 100 °C. And the resolution of difficult separated compounds, methane and ethane, can reach 12.98, which is 201.86 % higher than the silica-based monolithic capillary column in the relevant research. The resolution of ethane and ethylene reaches 6.81 at 120 °C. SignificanceThe μGCC fabricated by ULAE method is composed of all-glass and has the uniform stationary phase coating because of the homogeneous microchannel surface which greatly improve the separation performance, resulting in a large resolution for methane and ethane. The all-glass μGCC has broad application prospects in light hydrocarbon separation.

Seismic behavior of prefabricated beam-column joint with π-shaped connector

An innovative beam-column π-shaped joint, which was suitable for the low-rise prefabricated lightweight steel composite structure, was proposed in this paper. Firstly, with consideration of the variables of the column type, bending stiffness ratio between the beam and π-shaped connector, π-limb length, perforated end plate thickness, and with or without web connecting plate, twelve π-shaped joint specimens were prepared and their seismic behavior was experimentally investigated in aspects of failure mode, hysteretic performances, ultimate moment, stiffness degradation, deformation capacity, energy dissipation capacity, and strain response. Then the numerical model of the π-shaped joint was established and validated with the test data, which facilitates the further investigation of the influence of the bending stiffness ratio, π-limb length, and perforated end plate thickness on the seismic performance of the π-shaped joint. The test results showed that the application of the CFST column could improve the ultimate moment, initial stiffness, and energy dissipation of the π-shaped joint compared to the SHS column. Meanwhile, the introduction of the web connecting plate could avoid the separation of beam and column, resulting in a significant improvement in the seismic performance of the π-shaped joint. The test and numerical results demonstrated that decreasing the bending stiffness ratio, increasing the π-limb length and perforated end plate thickness was beneficial to further improve the seismic behavior of the π-shaped joint, and their corresponding suggested values were also provided in the present study.

Highly selective separation of germanium from sulfuric solution using an anion exchange D201 × 7 resin with tartaric acid

Germanium (Ge) exhibits excellent optical and electrical properties. Due to the low reserves of Ge and lack of independent mineral resources, zinc refinery residues have become an important source of Ge. In this work, a D201 × 7 resin has been employed in the selective separation of Ge from a sulfuric solution using tartaric acid as a complexing agent. In the sulfuric acid system, Ge(OH)4 was converted to an anionic complex [GeO2(OH)2C4H4O4]2− at a 1:1 tartaric acid to Ge molar ratio. The anion exchange D201 × 7 resin adsorbed the Ge tartrate anionic complex. The adsorption process exhibited pseudo-second-order kinetic behavior and adhered to the Langmuir isothermal adsorption model. The maximum adsorption capacity of D201 × 7 resin for Ge was 214 mg g−1. Selective Ge uptake and purification could proceed by column separation The results showed that enrichment factor was 74.7, and the desorption concentration of Ge was increased from 500 mg L−1 to 36.6 g L−1. The D201 × 7 resin exhibited high selectivity, excellent adsorption performance and good stability, making it a viable candidate in industrial applications.

General Two-Step Method for the Fabrication of Covalent-Organic Framework-Bound Open-Tubular Capillary Columns for High-Resolution Gas Chromatography Separation of Isomers.

Covalent organic frameworks (COFs) are promising as stationary phases for gas chromatography (GC). The successful anchoring of COFs to the inner walls of the capillary with good uniformity is an important prerequisite to ensure the excellent separation performance of columns. However, current methods for the fabrication of COF-based capillary columns cannot always meet this requirement when faced with different COFs, which hampers the further development of COF-based GC stationary phases. Here, we show a general two-step method for the fabrication of COF-bound capillary column. The first step enables the formation of uniform amorphous polymer layer on the inner walls of capillary, while the second step allows the facile transformation of the amorphous polymer layer into a highly crystalline COF layer. COF-bound capillary columns with different framework structures were fabricated successfully by the developed two-step method. Impressively, the COF layers bound on the inner walls of these capillary columns showed good uniformity and high crystallinity. More importantly, as an example, the fabricated Tab-DHTA-bound capillary column showed good resolution (R > 1.5) and high column efficiency (700-39,663 plates m-1) for the tested isomers of ethylbenzene, xylene, dichlorobenzene, chlorotoluene, pinene, 1,3-dichloropropene, and propylbenzene with good precision (RSD, run-to-run, n = 5) (retention time, 0.2-0.6%; peak area, 0.5-1.1%; and peak height, 0.5-1.4%). In general, the fabricated Tab-DHTA-bound capillary column exhibited better performance for the separation isomers than commercial columns DB-5 and HP-FFAP. These results indicate that the two-step method is an efficient way to fabricate the COF-bound capillary column with excellent separation performance.

Amide-decorated reusable C18 silica-packed columns for the rapid, efficient and sequential separation of lanthanoids using reversed phase-high performance liquid chromatography

The current work focuses on the sequential separation of trivalent lanthanides (except Pm3+) using modified C18 silica-packed supports through the reversed-phase high-performance liquid chromatography (RP-HPLC) technique. In the current research, four indigenously synthesized amphiphilic aromatic triamide derivatives, namely N1, N1, N3, N3, N5, N5-hexa(alkyl) benzene-1,3,5-tri carboxamide (alkyl = butyl, hexyl, octyl, and decyl), were employed as column modifiers. The results show that the separation of Ln3+ can be achieved systematically (< 12 min) by tuning the modifiers' functional group and hydrophobic chain and fine-tuning the column modification procedure and separation parameters. The chromatographic studies revealed that the use of 0.168 mmol of N1, N1, N3, N3,N5, N5-hexa(hexyl)benzene-1,3,5-tricarboxamide (HHBTA) coated column and 0.419 mmol of N1, N1, N3, N3, N5, N5-hexa(octyl) benzene-1,3,5-tricarboxamide (HOBTA) modified columns offered excellent separation for the lanthanoids, using 0.1 M α-hydroxyisobutyric acid (HIBA), as mobile phase. The separated lanthanoids were quantified by post-column derivatization reaction (after the separation process) using Arsenazo (III) as the post-column reagent by integrating with a UV–Visible detector fixed at 655 nm (λmax). A systematic study on the influence of various analytical features, such as the effect of the modifier's chain length and its concentration, mobile phase composition and pH, was performed and optimized for achieving the best separation protocols.

On‐line chloride removal from ion chromatography for trace‐level analyses of phosphite and other anions by coupled ion chromatography–inductively coupled plasma mass spectrometry

RationaleIon chromatography (IC) combined with inductively coupled plasma mass spectrometry (ICPMS) is an ideal tool for measuring low concentrations of anionic species such as phosphite; however, the high concentration of chloride and other anions in natural solutions may negatively impact chromatographic separation and data quality.MethodWe developed an on‐line mechanism of removing chloride from a sample within an ion chromatograph, using an additional valve and a separation column that transfers chloride to waste while phosphite and most other anions are retained. We installed this system in a coupled IC/ICPMS system (ICS6000 and Element 2 in medium‐resolution mode) and determined linearity and detection limits. In addition, we measured phosphorus species by NMR for comparison as an alternative method for phosphite determination.ResultsChloride was fully removed from the samples while phosphite was retained and could be analysed by IC/ICPMS. Concentrations could be measured down to 0.003 μmol/L and possibly less with good linearity over the explored range (up to 1.615 μmol/L; r2 = 0.999). In contrast, the detection limit by NMR was 6.46 μmol/L.ConclusionsThe on‐line removal mechanism works well for simplifying sample matrices. It removes the need for costly pre‐analytical sample treatment with OnGuard columns. We confirm that IC/ICPMS is the most powerful technique for quantifying phosphite in natural solutions. The new chloride‐removal method may also be applicable to analyses of other anions.

Multi‐interactions driven continuous removal of organic dyes from water by lignocellulosic‐based fibers

AbstractWater polluted by organic dyes is normally present in industrial production, which seriously threatens environmental safety. Research on dye adsorption has recently been related to nanomaterials due to their large specific surface area. However, there are still some problems associated with their preparation, application, and recovery. In this study, we developed the one‐step synthesis of lignocellulosic‐Fe(OH)3 hybrid fibers by in situ growth of Fe(OH)3 nanoparticles on lignocellulosic, which could be used as effective adsorbents for dye removal. The formed Fe(OH)3 nanoparticles were dispersed homogeneously on the surface of lignocellulosic. The as‐prepared hybrid fibers featured a large absorption capacity for methylene blue, up to 150.9 mg/g. In a fixed‐bed column separation process, dye pollutants were successfully removed from the water even at a high speed of 5.0 mL/min, with the separation efficiency higher than 99.99%. Remarkably, 1.0 g of lignocellulosic‐Fe(OH)3 was capable of separating over 1200 mL of dye solution continuously and thoroughly. Notably, the underlying adsorption mechanism analyses suggested that multi‐interactions of hydrogen bonds, π–π interactions, and coordinate bonds contribute to the adsorption ability of lignocellulosic‐Fe(OH)3.

Hirsutella sinensis mycelium polysaccharides attenuate the TGF-β1-induced epithelial-mesenchymal transition in human intrahepatic bile duct epithelial cells

Hirsutella sinensis is the anamorph of Ophiocordyceps sinensis, and its mycelia has been used to effectively treat a variety of hepatobiliary diseases in clinical practice. In the present study, we performed a systematic study on the composition and structure of its polysaccharides, and then employed a TGF-β1-induced human intrahepatic bile duct epithelial cell-epithelial-mesenchymal transition (HIBEC-EMT) model to investigate their effects on treating primary biliary cholangitis (PBC) based on hepatic bile duct fibrosis. Four polysaccharide fractions were obtained from H. sinensis mycelia by hot-water extraction, DEAE-cellulose column and gradient ethanol precipitation separation. HSWP-1a was an α-(1,4)-D-glucan; HSWP-1b and HSWP-1d mainly consisted of mannoglucans with a backbone composed of 1,4-linked α-D-Glcp and 1,4,6-linked α-D-Manp residues branched at O-6 of the 1,4-linked α-D-Glcp with a 1-linked α-D-Glcp as a side chain; and HSWP-1c mainly contained galactomannoglucans. These polysaccharide fractions protected HIBECs from a TGF-β1-induced EMT, according to HIBEC morphological changes, cell viability, decreased E-cadherin and ZO-1 expression, and increased vimentin and collagen I expression. Furthermore, the effects of the polysaccharides might be mediated by inhibiting the activation of the TGF-β/Smad signaling pathway, which attenuated hepatic bile duct fibrosis and potential PBC effects.

Influence of ohmic heating on structure, texture and flavor of peanut protein isolate

The impacts of ohmic heating (OH) on the physical structure and volatile compounds of peanut protein (PP) were investigated for low denaturation plant-based meat ingredient using peanut protein isolate (PPI). The microstructure, texture, color, polar and weakly polar volatile compounds were characterized qualitatively and quantitatively using colorimetry, scanning electron microscopy, texture analysis, headspace solid-phase microextraction, DB-WAX and DB-5MS columns for separation, and combination of gas chromatography (GC) and mass spectrometry (MS). The principal component analysis and partial least square discrimination were applied to the results of the volatile compounds attribution. The results showed that OH treatments modified the second and tertiary structure of PP, improved the texture, caused either disappearance of indigenous compounds or emerging of new volatile compounds. OH could reduce off-flavor and increase pleasant compounds of PPI. The findings suggested that the OH is promising in vegetable protein structure and flavor improvement.

Comparative analysis of isopropyl alcohol dehydration using ionic liquids and deep eutectic solvent

The current article deals with the separation of the azeotropic mixture of isopropyl alcohol (IPA) and water using an ionic liquid, 1-ethyl-3-methylimidazolium tetrafluoroborate ([EMIM][BF4]) and Deep Eutectic Solvents (DESs), Choline Chloride/glycerol (Glyceline) and Choline Chloride/Ethylene Glycol (Ethaline). Conventional dimethyl sulfoxide (DMSO) solvents are used to compare the results for IPA dehydration. Process modelling and simulation were carried out in the Aspen Plus simulator (v.8.6). The NRTL model was used to calculate the thermodynamic properties as well as the vapour-liquid equilibria of the ternary systems. The process parameters such as entrainer flow rate, binary feed stage, entrainer feed stage, column stages, reflux ratio, reboiler and condenser duties were evaluated using sensitivity analysis and design spec tools of the simulator. The industrial process for both systems, containing a separation column and a recovery column, was simulated at a steady state. Both processes were optimised using the optimisation tool of the simulator and compared based on the energy requirement. Further, based on the simulation results, we proposed an alternate process design for solvent recovery using a flash drum. The results show that more than 99.9 mol% IPA purity can be achieved using both ILs as well as DESs. The overall energy requirement for the separation of IPA-water mixture using [EMIM][BF4] entrainer in a conventional process was found to be lower than DMSO. The proposed alternate process further reduces the energy requirement compared to the conventional process for both IL and DESs systems.

Identification of Polymethoxyflavones (PMFs) from Orange Peel and Their Inhibitory Effects on the Formation of Trimethylamine (TMA) and Trimethylamine-N-oxide (TMAO) Using cntA/B and cutC/D Enzymes and Molecular Docking.

This study investigates the inhibitory effects of polymethoxyflavones (PMFs) on enzymes involved in the production of trimethylamine (TMA) and trimethylamine-N-oxide (TMAO). PMFs were isolated from Valencia orange peel and identified using column separation and NMR techniques. The findings reveal that nobiletin and 3,6,7,8,2',5'-hexamethoxyflavone significantly suppress cntA/B and cutC/D, respectively. Furthermore, 3,6,7,8,2',5'-hexamethoxyflavone decreases the level of TMAO formation by suppressing the FMO3 mRNA level. This study elucidates that specific structural features of PMFs can contribute to their interactions with enzymes. Our study represents the first demonstration of the ability of PMFs to mitigate the risk of cardiovascular disease (CVD) by inhibiting enzymes responsible for TMA production, which are generated by gut microbiomes. Furthermore, we introduce a novel model system utilizing TMA-induced HepG2 cells to assess and compare the inhibitory effects of PMFs on TMAO production. These findings could pave the way for the development of novel therapeutic approaches to manage CVD.

Efficient and selective capture of Au(III) from PCBs by pentaethylenehexamine-modified chloromethylated polystyrene beads.

Recycling of gold promotes solving the problems of resource waste and environmental pollution. In this work, pentaethylenehexamine (PEHA)-modified chloromethylated polystyrene beads (PEHA-CMPS) was synthesized for the recovery of Au(III) from actual printed circuits boards (PCBs) leaching solution. PEHA-CMPS exhibited excellent adsorption efficiency at a wide pH range. It was discovered that the pseudo-second-order and Langmuir model provided a superior match for the Au(III) adsorption process. The maximum adsorption capacity for Au(III) was 1186 mg/g. Furthermore, PEHA-CMPS was able to selectively capture trace Au(III) with recovery efficiencies of above 80% from the actual PCBs leaching solution. In addition, the column separation approach was utilized to better assess the practical applications for PEHA-CMPS, proving that the prepared adsorbent exhibited great prospects in industrial applications. The adsorption efficiency still maintained 95% after five adsorption-desorption cycles. The FTIR, XRD, and XPS analyses demonstrated that Au(III) uptake on PEHA-CMPS was a collaborative process involving electrostatic interaction, chelation, and oxidation-reduction. The PEHA-CMPS provided a promising strategy in Au(III) recovery and environmental remediation.

Simultaneously measure the concentrations of busulfan and phenytoin in human plasma using an HPLC-MS/MS method: Application to the TDM for children underwent hematological stem cell transplantation

AbstractIn this work, a simple and rapid high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method was developed and validated to carry out the simultaneous measurement of busulfan (BU) and phenytoin (PHT) in the plasma of children. In this method, plasma sample could be prepared by one-step protein precipitation using 1 mL of methanol/water (1:1, v/v). After centrifugation (14,500 rpm, 5 min, 4 °C), 10 μL of the supernatant was injected into a Hypersil Gold C18 column (150 × 2.1 mm, 5 μm, Thermo Fisher Scientific) for separation by gradient elution. Quantification was carried out using multiple reactions monitoring (MRM) under positive scan mode. In the method verification, the calibration curves of BU and PHT showed satisfactory linearity (r &gt; 0.99) at the concentration ranging from 0.02 to 20 μg mL−1. The accuracy and precision were tested at four concentration levels (including the LLOQ level) with the relative error (RE) ranging from −0.80% to 11.45% and coefficient of variation (CV) between 0.93% and 7.74%. There was no pronounced matrix effect to interfere with the quantitative analysis. Compared to determine BU and PHT using two individual methods, less pre-treatment process, labor and blood sample volume are required in this proposed method. Finally, this method was successfully applied to the therapeutic drug monitoring of BU and PHT for children underwent hematological stem cell transplantation.

Heterogeneous photocatalytic degradation of antiviral drug didanosine mediated by rose bengal and TiO2 nanoparticles.

There is a great concern among the researcher to remove the problem of the persistent organic pollutants in wastewater. Pharmaceutical agrochemical and personal care products are generally considered Persistent organic pollutants. Therefore, it is a matter of concern to develop new techniques how to remove these pollutants safely at low cost. This study mainly focuses on the commonly used antiviral drug didanosine and one most commonly used dye rose bengal. In this study, an organic dye rose bengal and TiO2 nanoparticles have been used in combination with UV light to achieve the photodegradation of selected pharmaceutical products and the dye was also degraded by using TiO2 Nanoparticles. The formation of three oxidation products was detected by using a very popular separation technique thin layer and column chromatography. The isolated photoproduct was characterized by using advanced characterization techniques like FTIR (Fourier transform infrared spectroscopy), UV Spectroscopy, and Proton and 13C NMR (Nuclear Magnetic Resonance spectroscopy). The role of singlet oxygen as an active species in this reaction was confirmed by using D2O as a reaction medium. The role of singlet oxygen in this photochemical reaction was also established by the addition of sodium azide. The TiO2 nanophotocatalyst efficiently degrade the didanosine and rose bengal in the presence of the UV light. In the TiO2-induced photocatalytic degradation of didanosine and dyes, the hydroxyl and superoxide radical anion play a prominent role. The finding of this manuscript is very useful to develop an efficient low-cost method for the treatment of wastewater contaminated by antiviral drugs, similar pharmaceutical products and dyes. This study was also very helpful to establish a plausible mechanism behind the phototoxicity of the didanosine.

Synergistically enhancing hydrogen bonding, hydrophobic interaction and electrostatic association of collagen fiber to flavonoid aglycones for their effective separation by polyethyleneimine modification

Compared with flavonoid glycosides, flavonoid aglycones are difficult to be separated since they have less hydroxyls. Collagen fiber (CF), a natural polymer, was once used as packing material for separation of kaempferol and quercetin (the typical flavonoid aglycones) after crosslinking by glutaraldehyde mainly based on hydrogen bonding and hydrophobic interaction in column length-diameter ratio of 60:1. Hydrophobic modification by grafting alkyl chains was then employed to enhance the hydrophobic interaction between CF and flavonoid aglycones, which can improve the separation efficiency and decrease column length-diameter ratio to 19:1. In order to further improve the adsorption capacity and separation efficiency, the strategy of simultaneously grafting hydrophobic alkyl chains (–CH2–CH2–) and alkali groups (–NH2) was adopted in this work to enhance hydrophobic interaction, hydrogen bonding and electrostatic association to flavonoid aglycones at the same time through grafting polyethyleneimine (PEI). PEI modified CF (PEI-CF) maintained the fiber structure of CF, and had higher adsorption extent and rate to flavonoid aglycones through the enhanced synergetic effect of hydrophobic interaction, hydrogen bonding and electrostatic association. As a result, PEI-CF presented a satisfactory column separation efficiency for kaempferol and quercetin even the length-diameter ratio of column was decreased to 11:1, which was much better than previously developed glutaradehyde-crosslinked collagen fiber and isobutyl-grafted collagen fiber, as well as commonly used polyamide and Sephadex LH-20.Graphical abstract