Fourier Transform Infrared Spectrometer Research Articles

Modification of Fe3O4 magnetic nanoparticles for antibiotic detection

The manufacture, modification, and application of surface-functionalized Fe3O4 nanoparticles in the extraction and isolation of antibiotics are reviewed in this paper. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) can be used to characterize the morphological features of Fe3O4 nanoparticles, while Fourier Transform Infrared Spectrometer (FTIR) and X-ray diffractometry (XRD) can be used to determine the crystalline shapes and distinctive functional groups of these particles. We gathered a lot of data to investigate the effects of experimental parameters like pH, adsorbent dosage, contact time, and ionic strength on the extraction of antibiotics from Fe3O4 magnetic nanoparticles. We additionally talked about the mechanism of action of magnetic nanoparticles for the extraction of separated antibiotics and how they are utilized in practical detection methods. This work concluded with an overview of the potential for environmental friendliness and dispersion of functionalized Fe3O4 nanoparticles, as well as potential challenges and directions.

Investigation on the Anisotropic Electrothermal Performance of Wood‐Based Graphene Electric Heating Composites

The unique material structure and pronounced anisotropy of wood bestow it with an array of remarkable properties, creating opportunities for designing functional materials. This study investigates the application of wood's anisotropic structure in temperature‐controlled intelligent electric heating materials by preparing wood‐based graphene electric heating composites (GNPs@EW). Graphene nanosheets (GNPs) are incorporated into a birch matrix (EW) to enhance the electrical and thermal conductivity of insulating wood. The integration of graphene with wood is confirmed through Fourier transform infrared spectrometer (FTIR) and X‐ray diffractometer (XRD) analysis. The optimal composite (GNPs@EW1) is prepared with graphene‐to‐anhydrous ethanol mass ratio of 1:1. The results demonstrate the influence of wood's anisotropy on the electrical and thermal conductivity of the composites, revealing superior performance in the axial direction compared to the tangential direction. The resistivity of GNPs@EW1 along the axial direction decreases by 2.1–2.9 times relative to the tangential direction, and the temperature rise after energization at 6 V is 22–29 °C higher in the axial direction. Furthermore, GNPs@EW1 exhibits thermal stability, enhanced axial mechanical properties, and temperature uniformity, establishing these superior axial properties as a foundation for the development of wood‐based heating materials and innovative smart heating applications.

Multi-scale analysis of mechanical properties of RCA based on synergistic modification of carboxylic butadiene-styrene latex and PVA fiber

With the rapid development of the construction industry, construction waste is also increasing day by day. Considering the utilization rate of recycled coarse aggregate (RCA) concrete and the mechanical strength of RCA itself, this study carried out collaborative modification of RCA through new modifiers carboxylic butadiene-styrene latex (CSBL) and PVA fiber, aiming at improving the mechanical properties of RCA. In this study, compressive test and shear test were used to test the mechanical strength of the test block. Scanning electron microscope (SEM) and Fourier transform infrared spectrometer (FTIR) were used to reveal the microscopic morphology and chemical composition, respectively. Molecular dynamics simulation was used to evaluate the type and stability of the force at the weak interface. The results showed that the modified compressive strength and shear strength of RCA with replacement rate of 20% increased by 12.8% and 26.7%, and the optimal content of CSBL and PVA fiber was 15% and 1.5%, respectively. CSBL further hydrates the unhydrated cement, thereby optimizing the weak interface. PVA plays a role in limiting the development of cracks in RCA. The results of weak interface molecular simulation show that CSBL acts as a bridge at the weak interface, and CSBL mainly enhances the adhesion between the weak interfaces in RCA through a large number of hydrogen bonds and stable ionic bonds. Therefore, CSBL improves the application effect of PVA fiber in RCA, and this study provides useful insights for improving the performance of RCA materials.

Novel Binary and Ternary Biocomposites (Zeolitic Imidazolate Framework (ZIF‐67), Graphene Oxide (GO) Nanosheet, and Guar Gum (GG) Biopolymer): Synthesis and Adsorption of Malachite Green Cationic Dye

AbstractAccording to the research, zeolitic imidazolate framework (ZIF‐67) and graphene oxide (GO) nanosheets were synthesized with a guar gum (GG) biopolymer substrate to form two‐component hybrid biocomposites: GO/ZIF‐67 (GOZ), GG/ZIF‐67 (GZ), and three‐component hybrid with GO/GG/ZIF‐67 (GGZ) substrate polymer. These composites were used to adsorb malachite green (MG) cationic dye from an aqueous solution at room temperature. The chemical fractions, morphological and structural properties of the hybrid biocomposites were determined using a Fourier transform infrared spectrometer (FTIR), scanning electron microscope (SEM), X‐ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) analyses. The adsorption of MG dye was carried out on the two‐component and three‐component hybrid biocomposites with a polymer substrate under different experimental conditions. The high surface area of GZ, GOZ, and GGZ was 1362.89, 754.89, and 833.67 m2 g−1, respectively, and the total pore volume was 0.90 cm3 g−1 for GZ, and 0.51 cm3 g−1 for GOZ and GGZ, respectively. The removal of MG pollutant follows the pseudo‐second order model and the Langmuir model. The adsorption mechanism involves hydrogen bonding, π‐π stacking, and electrostatic interactions. The GOZ, GZ, and GGZ hybrid biocomposites showed the maximum removal efficiency at 66.6%, 74.4%, and 90.1%, respectively. The data show that the removal of MG after 3 cycles was 90%, 86%, and 82%.

Environmental Aging Effects on the Thermal Oxidative Degradation and Mechanical Failure of HDPE

High-density polyethylene (HDPE) protective nets, manufactured by a construction materials company, experienced failure after just 6 months of use. In our study, HDPE pellets were processed using an extruder, compression molding machine, and cutting knife to prepare dumbbell-shaped specimens in accordance with the ISO 37-2017 standard. The specimens without any degradation treatment were named as HDPE-0d, while those subjected to 40 days of thermal oxidation aging were named as HDPE-40d. A range of analytical tools, including a universal testing machine, thermogravimetric analyzer (TGA), plate rheometer (MCR), Fourier-transform infrared spectrometer (FTIR), and scanning electron microscope (SEM), were employed to evaluate the mechanical properties, thermal stability, rheological behavior, chemical structure, and microstructure of the HDPE protective nets. The results indicated that prolonged exposure to thermal oxidation and excessive shear stress at the installation points were the principal factors contributing to the degradation of the HDPE nets. Based on these findings, practical recommendations are proposed to mitigate similar failures in the future, alongside potential enhancements in the material’s stability and anti-aging properties.

Catalytic and Tribological Performances of a Novel Bi-Functional Ionic Liquid in Lubricating Ester Oil

To address the detrimental effects of the residue of catalysts on the tribological performances of ester lubricants, a novel and efficient bi-functional ionic liquid 1-(3,5-di-tert-butyl-4-hydroxybenzyl)-3-methylimidazole di(2-ethylhexyl) phosphate ([(BHT-1)MIM][DEHP]) was prepared. The catalyst not only facilitates the synthesis of pentaerythritol tetra-hexanoate (PETH) through the catalytic esterification reaction—achieving up to 96% conversion with a 94% yield—but also enhances the tribological performance of ester oil PETH when used as a lubricant additive. The tribological property has been improved remarkably: the mean friction coefficient for PETH + [(BHT-1)MIM][DEHP] is notably lower, at 0.110, compared to the PETH, which has a coefficient of 0.180. Meanwhile, the wear scar diameter of the steel ball, when lubricated with PETH + [(BHT-1)MIM][DEHP], is notably smaller than that of a steel ball lubricated solely with PETH. Especially, the reduction in the wear volume at 100 °C is up to 81.46% compared with the base oil PETH. [(BHT-1)MIM][DEHP], PETH + [(BHT-1)MIM][DEHP], and the worn track of the upper running ball and lower disc were systematically characterized by using Nuclear Magnetic Resonance (NMR) spectra, a Fourier Transform Infrared Spectrometer (FT-IR), a field emission scanning electron microscope (FESEM), Thermal gravity analysis (TG), X-ray photoelectron spectroscopy (XPS), and an optical microscope (OM). The wear mechanism of the tailored lubricant oil was discussed in terms of the chemical composition of the worn surface.

Compact Quantum Cascade Laser-Based Noninvasive Glucose Sensor Upgraded with Direct Comb Data-Mining.

Mid-infrared spectral analysis has long been recognized as the most accurate noninvasive blood glucose measurement method, yet no practical compact mid-infrared blood glucose sensor has ever passed the accuracy benchmark set by the USA Food and Drug Administration (FDA): to substitute for the finger-pricking glucometers in the market, a new sensor must first show that 95% of their glucose measurements have errors below 15% of these glucometers. Although recent innovative exploitations of the well-established Fourier-transform infrared (FTIR) spectroscopy have reached such FDA accuracy benchmarks, an FTIR spectrometer is too bulky. The advancements of quantum cascade lasers (QCLs) can lead to FTIR spectrometers of reduced size, but compact QCL-based noninvasive blood glucose sensors are not yet available. This work reports on two compact sensor system designs, both reaching the FDA accuracy benchmark. Each design commonly comprises a mid-infrared QCL for emission, a multiple attenuation total reflection prism (MATR) for data acquisition, and a computer-controlled infrared detector for data analysis. The first design translates the comb-like signals into conventional spectra, and then data-mines the resultant spectra to yield blood glucose concentrations. When a pressure actuator is employed to press the patient's hypothenar against the MATR, the sensor accuracy is considered to reach the FDA accuracy benchmark. The second design abandons the data processing step of translating combs-to-spectra and directly data-mines the "first-hand" comb signal. Beyond increasing the measurement accuracy to the FDA accuracy benchmark, even without a pressure actuator, direct comb data-mining upgrades the sensor system with speed and data integrity, which can impact the healthcare of diabetic patients. Specifically, the sensor performance is validated with 492 glucose absorption scans in the time domain, each with 20 million datapoints measured from four subjects with glucose concentrations of 3.9-7.9 mM. The sensor data-mines 164 sets of critical singularity strengths, each comprising 4 critical singularity strengths directly from the 9840 million raw signal datapoints, and the 656 critical singularity strengths are subjected to a machine-learning regression model analysis, which yields 164 glucose concentrations. These concentrations are correlated with those measured with a standard finger-pricking glucometer. An accuracy of 99.6% is confirmed from the 164 measurements with errors not more than 15% from the reference of the standard glucometer.

CHARACTERIZATION OF GRAPHENE/H-BNNS REINFORCED HIGH-PERFORMANCE POLYURETHANE NANOCOMPOSITES PRODUCED USING SOLVENT CASTING METHOD

Polyurethane (PU) is a popular material for nanocomposites application in polymer science and technology. In pure form, PU is not suitable for engineering applications that require additional processing to improve the mechanical and thermal properties. High-performance PU nanocomposites with superior properties may be obtained by reinforcement with nanostructures such as graphene (Gr) and hexagonal boron nitride nanosheets (h-BNNS). In the present research, h-BNNS and Gr are used as a reinforcement into the PU matrix. Solvent casting method has been used to obtain PU/Gr, PU/h-BNNS, and PU/Gr + h-BNNS (hybrid) nanocomposites. Gr and h-BNNS are reinforced into the PU matrix at weight % (wt.%) of 0.3, 0.5, and 0.7, respectively. In hybrid PU nanocomposite the combination of both Gr and h-BNNS has been used in the wt.% of 0.3, 0.5, and 0.7. Characterization techniques such as Fourier transform infrared spectrometer (FTIR), field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and dynamic mechanical analysis (DMA) were employed to elucidate the morphological and structural changes within the PU nanocomposite matrix. Results revealed the establishment of polymerization in all three types of reinforcement and the presence of hard segments in the h-BNNS reinforced PU nanocomposites, which indicates the presence of hydrogen bonding. h-BNNS reinforced PU nanocomposites revealed the formation of strong interfacial interaction between the h-BNNS and the PU matrix. Significant changes in the storage modulus (E') were observed with the various types of reinforcing agents. Reinforcement of 0.5 wt.% of h-BNNS yields better results compared to Gr and hybrid reinforcement.

Synthesis of waterborne polyurethane-carboxymethyl chitosan cross-linked biodegradable bio-based porous materials for the adsorption of methylene blue.

The development of green and cost-effective biomass adsorbents is necessary for removing large amounts of dyes from wastewater. In this study, polyurethane prepolymers were synthesized using polycaprolactone diol (OH-PCL-OH), isophorone diisocyanate, and 2,2-dihydroxymethylpropionic acid, which were subsequently dispersed in aqueous carboxymethyl chitosan (CMCS) solution to produce waterborne polyurethane (WPU)-CMCS porous materials. The adsorbent was characterized by scanning electron microscopy (SEM), Fourier transform infrared spectrometer (FT-IR), thermogravimetric (TGA) and mercury intrusion porosimetry (MIP). The effects of pH, temperature, initial concentration and contact time on the adsorption properties of the adsorbents were investigated. The adsorption kinetics and isotherms were used to fit the adsorption data, and the reusability and biodegradability of the adsorbent were investigated. The results showed that the maximum adsorption capacity of WPU-CMCS10 was 222.65 mg·g-1 and the adsorption process followed the Langmuir model. After four adsorption-resolution cycles, the removal of dyes remained at 70.36 %, whereas in the biodegradability test, the mass loss of WPU-CMCS10 reached 43.04 % after 25 weeks, indicating that the adsorbent had good reusability and biodegradability.

Unveiling the crucial role of iron oxide transformation in simultaneous immobilization of nanoplastics and organic matter.

Nanoplastics (NPs) have been found in natural environments. However, the sequestration of NPs and natural organic matter (NOM) coupled with the Fe(III) hydrolysis and subsequent iron oxides transformation remains unclear. Here, we investigated the behaviors of NPs during the dynamic transformation process of iron oxides in the presence of humic acids (HA). The quantification results of europium chelate-labeled polystyrene (PS) NPs and HA indicate that 87.60% of NPs and 49.45% of HA were sequestered in the precipitate by the end of the transformation (240h). High-angle annular dark-field-scanning transmission electron microscopy-energy dispersive X-ray spectroscopy (HAADF-STEM-EDS) images show that NPs were doped into iron oxides during the recrystallization of ferrihydrite aggregates, while HA were adsorbed or penetrated into the nanoscale pores on the mineral surfaces, suggesting the formation of a stable iron oxides-NPs-NOM ternary nanocomplex with a core-shell structure. Fourier transform infrared spectrometer (FTIR) and two-dimensional correlation spectroscopy (2D-COS) analysis indicate that functional groups of iron oxides and HA, including hydroxyl, carboxyl, and FeO bonds, played a role in the binding process. In the presence of HA, the stability of the coprecipitation system was enhanced due to the increased electrostatic repulsion, which facilitated the full incorporation of NPs with iron oxides. These findings provide a new insight into the simultaneous immobilization of NPs and NOM.

Biodiesel synthesis via heterogeneous catalysis: application of new material based on mixed oxides (Na-FeAlO) obtained from the microstructural transformation of red mud

ABSTRACT This paper investigated the application of a new material based on mixed oxides (Na-FeAlO) as a catalyst, which was synthesized from red mud (RM) and sodium carbonate and named CLV98/900, in the production of fatty acid alkyl esters (FAAE) from waste cooking oil (WCO) via transesterification reaction. The synthesized catalysts were characterized by scanning electron microscopy (SEM), X-ray diffractometer (XRD), and Fourier transform infrared spectrometer (FTIR). The characterization of the catalyst indicated that the microstructural transformation of red mud into CLV98/900 efficiently obtained new crystallographic phases. The influence of several operational parameters, such as oil/alcohol molar ratio (1/15 – 1/45), temperature (65–75°C), percentage of catalyst (0–5%) and reaction time (60–180 min), was evaluated on the yield and conversion, resulting in yield values that ranged from 2% to 74%, 25% to 67.5%, 8% to 67.5% and 2% to 74%, respectively. In parallel, the conversion values ranged from 52% to 82%, 58% to 82%, 4% to 63% and 54% to 74%, respectively. The operational parameters fixed at an oil/ethanol molar ratio of 1/30, 70°C, 1% catalyst and 60 min provide the highest yield (82%) and conversion (82%). GC-MS analysis confirmed the formation of biodiesel. Therefore, CLV98/900 shows excellent potential as a catalyst for biodiesel production via WCO transesterification.

Theoretical Study of the Structural and Electronic Properties of NIPAM Polymer Dosimetry Gel

Background: Gel dosimeters consist of two types: Frick and Polymer, with compounds that are highly reactive to radiation. Objective: The difference in energy between the Highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) was investigated. Methods: An examination of the structure of a dosimetry gel polymer of type N- sopropylacrylamide (NIPAM) was carried out with the assistance of the Gaussian 09 software, the Fourier Transform Infrared Spectrometer (FTIR), the proton and carbon nuclear magnetic resonance (H NMR-C NMR), and the ultraviolet-visible spectroscopy (UV-vis) approach were used. The molecular geometry was determined using density functional theory (DFT) (B3LYP) and computational means. Subsequently, this molecule’s vibrational frequencies and electrical characteristics were examined, with the ground state represented by the 6-31G basis. The computations of the structure, as well as the vibrational frequencies and chemical shift, demonstrated a satisfactory theoretical approximation. Results: Based on the findings, it has been shown that NIPAM has a high-water solubility and is of great assistance in the process of introducing a powerful polar amide group into a hydrophobic polymer via the use of suspension or emulsion polymerization, and strong coupling effect (interaction of magnetic fields) between the hydrogen atoms and the deformation. Conclusions: The atoms within the structure, the molecule is highly reactive, the computed results demonstrated the accuracy of the theoretical approximation despite these discrepancies.

Real-Time In Vivo Human Skin Testing Using a Handheld Fourier Transform Infrared Spectrometer with a Three-Bounce Two-Pass Attenuated Total Reflection Interface.

Attenuated total reflection (ATR) Fourier transform infrared spectroscopy (FT-IR) is used to characterize a vast array of materials at the molecular level in various industry types. Here we compare the performance of a portable spectrometer with a novel three-bounce-two-pass (3B2P) ATR scanning interface to the same device with a standard one-bounce (1B) ATR, and to a benchtop spectrometer with a 10-bounce (10B) ATR, in ideal sample-interface conditions and an applied dermatological study setting. In both application settings, the benchtop 10B ATR interface showed the highest signal-to-noise ratio (SNR), however, the novel 3B2P produced a six-fold increase in the sensitivity of the portable spectrometer when analyzing isopropanol and showed the greatest consistency of SNR of all devices when analyzing isopropanol and in vivo skin samples. Spectral data were sourced from a recently undertaken dermatological study involving a cohort of 180 healthy, full-term babies, using both 1B and 3B2P interfaces. Use of the 3B2P interface resulted in a 55% greater successful high-quality spectrum collection rate, compared to the 1B, and showed significantly superior SNR at both observed study time points, i.e., birth (1B: 68.37; 3B2P: 77.37), and at four weeks (1B: 74.53; 3B2P: 80.22). The utility of ATR FT-IR spectrometers as a dermatological clinical tool was also exemplified here, by quantifying the moisture level of newborn skin. By gathering rich spectroscopic data on the molecular structure of the skin, this technique holds great promise for the quantification of skin disease-specific biomarkers.

Pilot scale application of 226Ra-contaminated soil leaching remediation

To address the issue of soil contamination caused by associated elements during the extraction and processing of radioactive minerals, this study employed two types of chemical leaching methods, one based on organic acids and the other on carbonates, to remediate radium-contaminated soil. Large-scale soil slurry reactors were used in field experiments to investigate the effects of acidic and alkaline leaching agents on the removal of 226Ra from naturally contaminated soil, and the optimal operational conditions were determined. The combined use of organic acids, salts and solubilizers has demonstrated high removal rates of radionuclide on a laboratory scale. Pilot scales revealed that using FeCl3, oxalic acid, NaClO2, and HEDP, or Na2CO3, NaHCO3, H2O2, and deep eutectic solvent (DES) as leaching agents achieved the best remediation outcomes for radium-contaminated soil. Under optimal conditions, the radium removal efficiencies of the two leaching systems reached 93.02% and 90.66%, respectively. Characterization analyses using X-ray diffraction (XRD), fourier transform infrared spectrometer (FT-IR), and scanning electron microscope (SEM) demonstrated that the chemical leaching methods are both safe and reliable, effectively removing radium while having minimal impact on the soil's original structure. Additionally, these methods have the potential to replenish soil nutrients and restore its functional use.

Activated Graphite@Nickel Oxide Nanoflowers for the Dispersive Solid-Phase Microextraction (DSPE) of Copper(II) from Water and Food

Activated graphite@NiO nanoflowers was synthetized and characterized by field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and Fourier transform infrared spectrometer (FTIR). It was used as adsorbent for dispersive solid-phase microextraction of Cu(II). The quantitative recovery values were found as pH 8.0, eluent 2.0 M HNO3, vortex time 30 s, adsorbent mass 20 mg, and preconcentration factor 80. The limits of detection and quantification were calculated as 4.23 µg L−1 and 14.1 µg L−1, respectively. The presented method was validated by the analyzing certified reference materials. It was sapplied to determination of copper contents of food and water samples.

Impact of biochar prepared at different pyrolysis temperatures on the methane production and microbial community structure of food waste anaerobic digestion

Biochars were prepared through the pyrolysis of sawdust at 300 °C, 500 °C, and 700 °C, respectively, under oxygen-limited conditions. The basic physicochemical properties of biochars were explored by scanning electron microscope (SEM), energy dispersive spectroscopy (EDS), surface area and porosity analyzer (BET), and Fourier-transform infrared spectrometer (FTIR). The effects of biochar addition on the methane yield and microbial community structure of anaerobic digestion of food waste were also investigated. SEM images showed that biochar had a honeycomb-like pore structure, EDS analysis showed that the C content in the biochar tended to increase, and the O contents tended to decrease with the increasing temperature. The specific surface area of biochars increased from 1.2014 m2/g (300 °C) to 326.8435 m2/g (700 °C). FTIR analysis showed that the number of different surface functional groups decreased with the increasing temperature. The addition of biochar could increase the cumulative methane volume by 11.63%–25.18%. High-throughput sequencing results showed that biochar addition could increase the relative abundance of Bacteroidetes, Chloroflexi, Firmicutes, Proteobacteria, and Spirochaetota, which were associated with the degradation of refractory organic matters. Meanwhile, biochar addition could enrich the relative abundance of methanogens participating in direct electron transfer (Methanosaeta and Methanosarcina), and methanogens producing methane through multiple pathways (Methanobacterium and Methanosarcina). The addition of biochar derived at 700 °C significantly increased the relative abundance of Methanobacterium and Methanosarcina from 1.96% and 0.70% (control group) to 32.68% and 64.69%, respectively and improved methane production by transforming acetoclastic/hydrogenotrophic methanogenic pathways to more metabolically diverse methanogenic pathways.

Mixed surfactants with solubilization behaviors: Separation of feldspar and quartz by self-assembly flotation

This study designed a mixed surfactant with solubilization behavior for selective flotation separation of feldspar and quartz. By optimizing the compounding ratio and dosage of reagents, the optimal mixed surfactants, dodecylamine (DDA), sodium dodecyl sulfate (SDS), and dodecane with the concentrations of 1.75, 0.58, and 3.5 mmol/L, used in flotation separation of feldspar and quartz has the maximum flotation difference of 91.36 % at pH 3 for single mineral. The result of flotation experiments of artificial-mixed-ore shows that the Al2O3 grade was maintained at 14.23 %, and Al2O3 recovery was achieved at 69.21 % for the froth product with a selectivity index (SI) of 1.59. The bench-scale flotation tests confirmed a better effect by using mixed surfactants with Al2O3 grades of 14.72 % and the Al2O3 recovery of 66.62 %. The separation mechanism of quartz and feldspar was proposed through analyses of critical micelle concentration (CMC), fourier transform infrared spectrometer (FTIR), contact angle, zeta potential, microscopy image, and X-ray photoelectron spectroscopy (XPS) measurements, and indicated that the flotation difference between quartz and feldspar mainly originated from the selective adsorption of anions on feldspar and the aggregation and subsidence of quartz in mixed surfactants.

Polymerization of acrylonitrile in dimethyl carbonate: A kinetic and mechanistic study

For the first time, a new polymerization medium, dimethyl carbonate (DMC), was used for the polymerization of acrylonitrile (AN), and polyacrylonitrile (PAN) powder was obtained successfully. The effects of polymerization factors, including monomer concentrations, temperature and initiator concentrations on the structures and properties of PAN powders were investigated by nuclear magnetic resonance spectroscopy (NMR), total internal reflectance Fourier transform infrared spectrometer (FTIR), wide-angle X-ray diffractometer (WXRD) and thermal gravimetric analyzer (TGA). The polymerization kinetic and mechanistic study of PAN with DMC as the polymerization medium were discussed in details. There are three key achievements in this paper. First, the kinetic equation of PAN polymerization with DMC as a medium was established: Rp = K[ABVN]0.92[AN]6.78. This result shows that the Rp is highly dependent on the AN concentrations. Second, the chain transfer constant of DMC was measured to be 4.57 × 10−4 at 60 °C, and the chain transfer constant increases with polymerization temperature. Lastly, the structures and properties of PAN powders prepared with H2O, tetrahydrofuran (THF) and DMC as media were compared. The results showed that the PAN prepared with DMC as a medium by free radical polymerization had a higher conversion, molecular weight and better crystalline property compared to THF. These findings indicate that DMC is a promising medium for manufacturing high quality PAN powder by free radical polymerization.

Understanding the role of sodium lignosulphonate on obstructing the aggregation of fine serpentine particles on to the hydrophobized pyrite surface

The slime coatings of serpentine via its hydrophobic Si-O layers significantly weaken the floatability of the hydrophobized sulfide minerals. In this paper, sodium lignosulphonate (SLS) was adopted to avoid the aggregation of fine serpentine particles on to the hydrophobized pyrite surface. The micro-flotation findings indicated that for the artificial mixture of pyrite and serpentine (2:1 mass ratio), 1.0 × 10–4 mol/L sodium isobutyl xanthate (SIBX) only floated out ∼22 % pyrite at pH ∼9.0, while, after extra addition of 70 mg/L SLS, the floatability of pyrite was restored and its recovery reached ∼90 %. In situ AFM (Atomic Force Microscope), contact angle, zeta potential, fourier transform infrared spectrometer (FTIR) and optical microscope deduced that the strong affinity of SIBX to pyrite rendered it replace the most part of the pre-aggregated SLS from pyrite surface, thus to restore the hydrophobicity of pyrite and further decrease the zeta potential. In addition, SLS attached on the positively-charged Mg sites of serpentine through its carboxyl and phenolic hydroxyl groups reduce the hydrophobicity and zeta potential of serpentine. While, the hard base O atom/anion exhibited much stronger affinity to hard acid Mg cation than that of the soft base S atom/anion, SIBX hardly replaced the adsorbed SLS from serpentine surface. Therefore, the increased electrostatic repulsion and weakened hydrophobic attraction between the SLS-adsorbed serpentine and SIBX-hydrophobized pyrite avoided their aggregation. The combination of SLS and SIBX realized the selective flotation separation of pyrite from serpentine.

Investigation and characterization of deep eutectic solvent (DES) based stationary phase in gas chromatography

In this study, the preparation of the stationary phase based on the deep eutectic solvent (DES) was investigated along with the measurement of thermodynamic parameters. The physical characterization of the synthesized sample was investigated by Thermogravimetric (TGA), scanning electron microscope (SEM) and Fourier Transform Infrared Spectrometer (FTIR) analyses. Thermodynamic parameters measured to express the potential ability of the constructed stationary phase were McReynolds constants, partition coefficient, Abraham system constants, ∆, activity coefficient at infinite dilution (γi∞), and selectivity (Sij∞). For this purpose, the parameters were investigated in different amounts of stationary phase (SP) loading including 5, 10, 15 and 18 %w/w and also at three temperatures of 40, 70 and 100 °C. The prepared stationary phase with moderate polarity had the potential to separate BTEXs, aromatic compounds and alcohols due to strong interactions caused by hydrogen bonds. It was investigated the improved performance of the stationary phase prepared with carbowax. Finally, the performance of SP-DES stationary phase separation was investigated for different analytes including alkanes, alcohols and aromatic compounds.