Fourier Transform Infrared Absorption Spectroscopy Research Articles

Tangerine fruit peel extract mediated biogenic synthesized silver nanoparticles and their potential antimicrobial, antioxidant, and cytotoxic assessments

Abstract The utilization of plant bioactive composites has concerned substantial attention due to their possible use in the development of novel antibiotics, containing the environmentally sustainable synthesis of nanoparticles. In the current study, a green and eco-friendly process was employed to synthesize silver nanoparticles (Ag-NPs) and to evaluate their anti-bacterial, anti-oxidant, and anti-cancer potentials. The characterization of the Ag-NPs involved UV-vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR), energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The UV-vis spectrum of Ag-NPs was 437 nm. The FTIR absorption peaks detected at 685.48 cm−1 confirmed their characteristics. The FESEM displayed that Ag-NPs have an average size of 30 nm. The TEM revealed that the Ag-NPs have an irregular spherical shape with 16 nm size distribution. The XRD results provided a strong indication that the green synthesized Ag-NPs was of high purity with crystalline nature. The anti-bacterial properties were investigated at different concentrations for both the ethanolic tangerine peel extract and Ag-NPs. The results of anti-bacterial activity showed that 100 µg·mL−1 was potent concentration, but the Ag-NPs were more effective than the ethanolic tangerine peel extract. For the ethanolic extract, the inhibition zone was 17.50 ± 0.20 mm for K. pneumoniae and 14.40 ± 0.20 mm for B. cereus. For the Ag-NPs, the inhibition zone was 25.50 mm for K. pneumoniae and 20.50 mm for B. cereus. Furthermore, the antioxidant examination revealed more potent free radical scavenging activity of the Ag-NPs than the ethanolic peel extract alone. The ethanolic extract ranged 46–77% while the Ag-NPs ranged 57–88%. Additionally, the anti-proliferative of the Ag-NPs against the lung cancer cell line (A549) was more potent than the ethanolic extract alone. The cytotoxic activity was 90.03% and 78.50%, respectively. The anti-proliferative effect of Ag-NPs is attributed to cell death, induced apoptosis, and enhanced generation of reactive oxygen species. Our findings highlight the potential and further utilization of Ag-NPs in medicinal applications particularly for cancer therapeutics.

Influence of Carboxymethyl Chitosan and Sodium Humate Composite Corrosion Inhibitor on the Corrosion Resistance of EH40 Steel in Seawater.

In this study, corrosion weight loss experiments were conducted to explore the corrosion-inhibiting properties of a composite inhibitor consisting of carboxymethyl chitosan (CMCS) and sodium humate (SH) at varying concentrations on EH40 steel in seawater. An investigation was conducted into the electrochemical behavior of EH40 steel in seawater and the mechanism of composite inhibitor consisting of carboxymethyl chitosan (CMCS) and sodium humate (SH) at varying concentrations on EH40 steel in seawater through an electrochemical test. X-ray photoelectron spectroscopy (XPS), scanning electron microscopy and energy-dispersion spectroscopy (SEM-EDS), Fourier transform infrared absorption spectroscopy (FTIR), and contact angle measurements were performed to confirm the mechanism of CMCS and SH as well as their composite corrosion inhibitors at the interface between seawater and EH40 steel. Furthermore, density functional theory (DFT) calculation supports the experimental findings. The results show that CMCS, SH, and their composite inhibitor are a mixed type of corrosion inhibitor that mainly inhibits cathodic reactions and corrosion through the active site blocking mechanisms. Their corrosion inhibition effect increases with the increase of mass concentration, and the composite inhibitor performs better in corrosion inhibition and scale inhibition than the individual inhibitor. When the CMCS mass concentration reaches 100 mg/L and the SH mass concentration reaches 50 mg/L, the corrosion inhibition rate is 74.65%, the corrosion potential shifts by about 47.39 mV, the Rp value increases from 358.6 to 1102.4 Ω·cm2, and the Ydl value decreases from 177.31 Sn Ω-1cm-2 × 10-6 to 92.672 Sn Ω-1cm-2 × 10-6. CMCS and SH are adsorbed onto the surface of EH40 steel, forming a protective film through the complexation of carboxyl, amino, and other functional groups to inhibit corrosion and prevent the further formation of scale. In addition, synergistic coadsorption occurs between CMCS and SH, and the composite corrosion inhibitor exerts a better effect than the individual corrosion inhibitor.

Structure and Stability of Charge-Coupled Lanthanide-Substituted Ca10(PO4)6F2 as a Potential Fluoride Bearing Nuclear Waste Form.

The structure and stability of charge-coupled lanthanide-substituted Ca10(PO4)6F2 as a potential fluoride-bearing nuclear waste form for the back-end fuel cycle of Gen-IV molten salt reactor have been studied in detail. Here, calcium fluorapatite (CaFAp) as a model structure was taken for incorporation of trivalent lanthanides (Lns, La-Lu except Pm) in a charge-coupled fashion, i.e., 2Ca2+ = Na+ + Ln3+. In these fluorapatite phases, Na+ is substituted exclusively at nine coordinated sites, Ca1, while Ln3+ is preferentially substituted at seven coordinated sites, Ca2. These compositions are further characterized for the local structure by Fourier transform infrared (FTIR) and Raman spectroscopy. Thermal expansion was measured by high-temperature X-ray diffraction (XRD) and the instantaneous thermal expansion coefficient correlates well with the unsubstituted CaFAp. The heat capacities of these solids were measured by differential scanning calorimetry and drop calorimetry, whereas enthalpies of formation were obtained by high-temperature oxide melt solution calorimetry. The thermodynamic analysis demonstrated that lanthanides having ionic radii closure to Ca2+ (Sm3+ and Gd3+) imparted higher thermodynamic stability to the substituted CaFAp as compared to that of other Ln3+. According to structural and thermodynamic investigations, entropy-stabilized fluorapatite waste from NaPr0.125Nd0.125Sm0.125Eu0.125Gd0.125Tb0.125Dy0.125Ho0.125Ca8(PO4)6F2 (WF-Ln) was successfully synthesized for the first time. Furthermore, electron beam irradiation studies probed by XRD, FTIR, Raman, and X-ray absorption (XAS) spectroscopy implied the radiation resistance nature of this substituted CaFAps up to 20 MGy.

Nanosecond repetitively pulsed plasmas with MHz bursts for CO2 dissociation

A novel pulsed power source capable of nanosecond pulses with burst frequencies up to 1 MHz is employed to create atmospheric pressure pulsed plasma in pure CO2 gas. The short bursts contain up to four nanosecond pulses. The CO2 conversion and corresponding energy efficiency are measured ex-situ with Fourier-transform infrared absorption spectroscopy. Trends in the absorption line profile of in-situ quantum cascade laser infrared absorption spectroscopy indicate an elevated vibrational temperature of CO2 with an increasing number of pulses per burst. The key result of this paper is that the dissociation energy efficiency is higher when operating the plasma in burst mode. Furthermore, a larger number of pulses in a burst is associated with a further increase of the dissociation efficiency. The highest efficiency measured is (17.7±0.3) % for single pulses spaced 2 ms apart, and (20.0±0.3) % for bursts of three pulses, with an in-burst frequency of 1 MHz and bursts spaced 4 ms apart.

In vitro chemical treatment of silk increases the expression of pro-inflammatory factors and facilitates degradation in rats.

Silk fiber is difficult to degrade in vivo, which limits its application in tissue engineering materials such as artificial nerves. Therefore, in this study aim to promote its degradation in vivo by chemical treating silk fibers in vitro. Sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), scanning electron microscopy (SEM) observations, mechanical test, Fourier transform infrared spectroscopy (FT-IR) measurements were used to investigate the degradation effect of chemicals (hydrochloric acid, phosphoric acid, acetic acid, sodium hydroxide, calcium hydroxide, sodium bicarbonate, and calcium chloride) on silk fiber in vitro. Immunofluorescence staining and transcriptome analysis were used to investigate the effect of inflammatory factors on the degradation of chemically treated silk fiber in rats. (1) Silks were separated into finer fibers in each group. (2) FT-IR absorption peaks of amides I, II, and III overlap in each group. (3) Silk degradation degree in each group was higher than that in an untreated group. The calcium chloride-treated group was completely degraded. (4) Fibronectin, collagen I, collagen III, integrin α and CD68 were immunofluorescence positive in all vegetation section. (5) There were no significant differences in the expressions of collagen I, collagen III, and fibronectin in the vegetations formed on the 14th day of subcutaneous implantation, while integrin α, CD68, TNF-α, IL-1b, and IL-23 express at higher levels with IL-10 at lower levels. All chemicals could completely degrade silk; however, their degradation products were not the same. The chemicals change the mechanical properties of silk by separating it into finer fibers, which increase the contact surface area between the silk and tissue fluid, accelerating the degradation of monofilaments in vivo by promoting inflammation and macrophage activity through the increased and decreased expressions of pro- and anti-inflammatory factors, respectively.

Assessment of Hydrothermal Treatment Effects on Coir Fibers for Incorporation into Polyurethane Matrix Biocomposites Derived from Castor Oil.

The incorporation of natural lignocellulosic fibers as reinforcements in polymer composites has witnessed significant growth due to their biodegradability, cost-effectiveness, and mechanical properties. This study aims to evaluate castor-oil-based polyurethane (COPU), incorporating different contents of coconut coir fibers, 5, 10, and 15 wt%. The investigation includes analysis of the physical, mechanical, and microstructural properties of these composites. Additionally, this study evaluates the influence of hydrothermal treatment on the fibers, conducted at 120 °C and 98 kPa for 30 min, on the biocomposites' properties. Both coir fibers (CFs) and hydrothermal-treated coir fibers (HTCFs) were subjected to comprehensive characterization, including lignocellulosic composition analysis, scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The biocomposites were subjected to water absorption analysis, bending tests, XRD, SEM, FTIR, and TGA. The results indicate that the 30 min hydrothermal treatment reduces the extractive content, enhancing the interfacial adhesion between the fiber and the matrix, as evidenced by SEM. Notably, the composite containing 5 wt% CF exhibits a reduced water absorption, approaching the level observed in pure COPU. The inclusion of 15 wt% HTCF results in a remarkable improvement in the composite's flexural strength (100%), elastic modulus (98%), and toughness (280%) compared to neat COPU. TGA highlights that incorporating CFs into the COPU matrix enhances the material's thermal stability, allowing it to withstand temperatures of up to 500 °C. These findings underscore the potential of CFs as a ductile, lightweight, and cost-effective reinforcement in COPU matrix biocomposites, particularly for engineering applications.

Fabrication of superhydrophobic cauliflower-like Cu[sbnd]Co coating with anti-corrosion and anti-fouling properties on B10 copper–nickel alloy welded joint

A superhydrophobic CuCo coating is successfully applied to the surface of a B10 copper–nickel (CuNi) alloy welded joint via electrodeposition and modification using a low-surface-energy material (stearic acid). The static water contact angle is measured to be 162.2 ± 1°, and the roll off angle is 2.1°. Various techniques, including scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, X-ray photoelectron spectroscopy, and Fourier-transform infrared absorption spectroscopy are employed to characterize the chemical composition and phase structure of the samples before and after electrodeposition and modification. The corrosion resistance of the superhydrophobic samples is evaluated via electrochemical impedance spectroscopy, potentiodynamic polarization, and scanning Kelvin probe microelectrochemistry. The results indicate that the superhydrophobic coating exhibits greater charge transfer resistance, lower self-corrosion current density, and higher surface work function, thus effectively enhancing the corrosion resistance of the B10 CuNi alloy welded joint. Furthermore, the micro-nano rough structure with low surface energy on the superhydrophobic sample surface traps air and forms an air layer, thereby reducing the contact between the corrosive medium and welded joint as well as minimizing corrosion. The superhydrophobic coating demonstrate thermal stability as well as excellent self-cleaning and mechanical properties, based on comprehensive testing and analysis.

Spectroscopic Identification of Bacteria Resistance to Antibiotics by Means of Absorption of Specific Biochemical Groups and Special Machine Learning Algorithm.

FTIR (Fourier transform infrared spectroscopy) is one analytical technique of the absorption of infrared radiation. FTIR can also be used as a tool to characterize profiles of biomolecules in bacterial cells, which can be useful in differentiating different bacteria. Considering that different bacterial species have different molecular compositions, it will then result in unique FTIR spectra for each species and even bacterial strains. Having this important tool, here, we have developed a methodology aimed at refining the analysis and classification of the FTIR absorption spectra obtained from samples of Staphylococcus aureus, with the implementation of machine learning algorithms. In the first stage, the system conforming to four specified species groups, Control, Amoxicillin induced (AMO), Gentamicin induced (GEN), and Erythromycin induced (ERY), was analyzed. Then, in the second stage, five hidden samples were identified and correctly classified as with/without resistance to induced antibiotics. The total analyses were performed in three windows, Carbohydrates, Fatty Acids, and Proteins, of five hundred spectra. The protocol for acquiring the spectral data from the antibiotic-resistant bacteria via FTIR spectroscopy developed by Soares et al. was implemented here due to demonstrating high accuracy and sensitivity. The present study focuses on the prediction of antibiotic-induced samples through the implementation of the hierarchical cluster analysis (HCA), principal component analysis (PCA) algorithm, and calculation of confusion matrices (CMs) applied to the FTIR absorption spectra data. The data analysis process developed here has the main objective of obtaining knowledge about the intrinsic behavior of S. aureus samples within the analysis regions of the FTIR absorption spectra. The results yielded values with 0.7 to 1 accuracy and high values of sensitivity and specificity for the species identification in the CM calculations. Such results provide important information on antibiotic resistance in samples of S. aureus bacteria for potential application in the detection of antibiotic resistance in clinical use.

Polypyrrole/zinc oxide/zeolitic imidazolate framework (PPy/ZnO/ZIF67) nanocomposites modified electrode for electrochemical analysis of Cd2+ and Pb2+ in waters

The electrochemical analysis of cadmium and lead ions was studied using a polypyrrole/zinc oxide/zeolitic imidazolate framework (PPy/ZnO/ZIF67) nanocomposite modified electrode in waters. Polypyrrole nanowires (PPy) were synthesised by chemical oxidation method and then zinc oxide (ZnO) was synthesized on it by hydrothermal method. The metal-organic framework material ZIF67 was prepared by solvothermal method in situ growing on PPy nanowires, which can improve the stability and electroconductivity of ZIF67, which were beneficial to increase the electrochemical active. The structure of the nanocomposites was characterized by transmission electron microscopy (TEM), Fourier transform infrared absorption spectroscopy (FTIR) and X-ray diffraction (XRD). In contrast, PPy/ZnO/ZIF67 has higher peak current and electrochemical properties. The peak current response of Cd2+ and Pb2+ detected by the PPy/ZnO/ZIF67 modified electrode showed a good fit in a wide range. The fabricated electrochemical sensor detects Cd2+ and Pb2+ individually and simultaneously. The limit of detection (LOD = 3σ/k) for the individual detection of Cd2+ and Pb2+ were 6.92 μg/L and 1.49 μg/L, respectively, with detection ranges from 20 μg/L to 3000 μg/L and 5 μg/L to 4000 μg/L. The selectivity and practicality of the PPy/ZnO/ZIF67 modified electrode were verified by the anti-interference experiment and the analysis of actual water samples.

Effect of Coconut Fiber Biochar and Its Nitrate Modification on Pb Passivation in Paddy Soils

The effects of coconut fiber biochar (CFB) and nitrate-modified coconut fiber biochar (NCFB) on the passivation of exogenous lead (Pb) in paddy soils and their underlying mechanisms were investigated using soil incubation experiments combined with spectroscopic techniques such as scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), synchrotron radiation X-ray fluorescence (SRXRF), and Fourier transform infrared absorption spectroscopy (FTIR). The effects of NCFB and CFB on the passivation of exogenous lead (Pb) in paddy soils and its underlying mechanisms were investigated. Compared with that of CFB, the inner wall of NCFB honeycomb pores was rougher, and the amount of alcohol-phenol-ether functional groups containing the C-O structure and the amount of carboxyl groups containing the C[FY=,1]O/O[FY=,1]C-O structure on the surface of CFB was significantly decreased after nitric acid modification. Compared with that in the control (without biochar) paddy soil after 150 d of incubation, the EDTA-extracted Pb content in the paddy soil with CFB and NCFB was reduced by 39.7% and 105.4%, respectively. The carbonate-bound and Fe-Mn oxide-bound Pb contents were significantly lower, and the organic-bound and residue Pb contents were significantly higher in the NCFB-added soil. The SRXRF scans showed that the exogenous Pb was enriched in the microregions of CFB particles rich in Ca and Cu elements and relatively less so in the microregions of soil aggregates rich in the Fe, Mn, and Ti elements. In addition, the characteristic peaks of carboxylates (1384 cm-1) in A-CFBPb and A-NCFBPb were significantly enhanced in the incubation experiment in the presence of exogenous Pb compared to A-CFB and A-NCFB in the absence of exogenous Pb. The addition of CFB or NCFB was more effective in passivating exogenous Pb in paddy soils and promoted the gradual transformation of Pb from unstable to more stable forms in paddy soils to achieve the effect of passivating Pb. The greater amount of carboxyl functional groups in NCFB participated in the passivation of exogenous Pb, which made NCFB more effective than CFB in passivating Pb. NCFB was more effective than CFB in passivating exogenous Pb in paddy soils due to its rougher inner walls of honeycomb pores and abundant carboxyl functional groups. In tropical areas such as Hainan, coconut fiber biochar and its modification can be considered as an environmentally friendly candidate method for the remediation of soil Pb contamination.

Ammonia generation in Ns pulse and Ns pulse/RF discharges over a catalytic surface

Plasma-catalytic ammonia synthesis in a ns pulse discharge and a ‘hybrid’ ns pulse/RF discharge in plane-to-plane geometry is studied by Fourier Transform infrared absorption spectroscopy. The data are taken in a preheated H2–N2 mixture, with and without Ni/γ-Al2O3 or Co/γ-Al2O3 catalyst placed in the discharge section. The measurement results are taken using two different approaches. The first is a ‘single-stage’ process, where a ns pulse discharge in the H2–N2 mixture is sustained continuously. In this case, the ammonia yield increases slowly, over a period of tens of minutes. The second is a ‘two-stage’ process, where the catalyst is first activated by the ns pulse discharge sustained in pure nitrogen, and then the activated catalyst is exposed to the H2–N2 flow, with or without the discharge. In this case, a strong overshoot of the NH3 number density at the reactor exit is detected, by over a factor of two compared to the single-stage process. After the initial overshoot, the ammonia yield gradually decreases to the ‘single stage’ value (with the discharge on), or to near zero (with the discharge off). The results demonstrate that the ammonia yield in the plasma-catalytic reactor is controlled by the N atom accumulation on the catalyst surface, which reacts with H atoms thermally dissociated on the catalyst or generated in the plasma. The results also show that the plasma-catalytic ammonia yield is significantly higher compared to that in the ns pulse discharge without the catalyst. The accumulation of H atoms on the catalyst, with their subsequent reactions with N atoms generated in the plasma, is of relatively minor importance at the present conditions. An additional series of measurements was made with a sub-breakdown RF waveform overlapped with the ns pulse discharge train, to enhance the vibrational excitation of nitrogen. The ammonia yield measured with the RF waveform added is approximately 20% higher compared to that at the baseline ns pulse discharge conditions, both with and without the catalyst. This effect is weaker compared to that of the catalyst activation by N atoms. Additional data are necessary to isolate the possible effect of the vibrationally excited N2 molecules on the ammonia synthesis in the plasma catalytic reactions.

Mineralogical and spectral characteristics of Changbai jade, Jilin province, Northeast China

Changbai jade is a type of jade ore with good economic value that is found in the tuff of the Upper Triassic Changbai Formation of the Mesozoic period in Jilin Province, China. However, the mineral composition of the kaolinite group in Changbai Jade has not been definitively identified, and there has been a lack of systematic mineralogical and spectral analysis. To analyze the mineralogical and spectroscopic characteristics of Changbai jade, this study utilized several modern testing methods, including X-ray fluorescence spectrometry (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometry (EDS), Fourier transform infrared absorption spectroscopy (FTIR), Raman spectrum test (Raman), and Ultraviolet visible (UV-vis). Mineralogical and spectroscopic analyses were conducted on Changbai jade ore samples CB21 and CB22. The results indicated that the main metamorphic minerals of the two samples are dickite and the color-causing factor of the yellow part is pyrite. This research provides basic theoretical research data for jade processing technology and the geological origin of Changbai jade.

Removal of heavy metals lead and ciprofloxacin from farm wastewater using peanut shell biochar

In this paper, peanut shells were used as the raw material for preparing biochar (PBC), and artificial simulated aging was used to age the PBC. To investigate the effectiveness of biochar before and after aging for the removal of Pb and ciprofloxacin (CIP) alone and the feasibility of simultaneous removal of Pb and CIP. The effects of different aging methods on the physicochemical properties of biochar were investigated by measuring the specific surface area (BET), scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared absorption spectrometry (FTIR) of biochar. The results showed that the C content of biochar decreased after aging, while the O/C, H/C, (N+O)/C, and O contents increased. Kinetic adsorption, adsorption isothermal and competitive adsorption experiments were performed to study the adsorption properties of CIP and Pb2+ by aging biochar under single and combined pollution systems. Aging inhibited the adsorption of ciprofloxacin on biochar, and the inhibition size was ranked as high-temperature aging > freeze-thaw cycles aging > natural aging. However, the effect of aging on the adsorption of Pb2+ by biochar was insignificant. Pb2+ in the complex contamination system would compete with CIP for oxygen-containing functional groups and adsorption sites on biochar, indicating that the pollutant adsorption mechanism by biochar is complex and influenced by various factors such as aging methods and pollutant species. This study shows that regional climatic factors and target pollutant species must be considered when applying biochar for pollutant removal, which may affect the long-term effects of pollution remediation.

Determination of the supramolecular arrangement of Dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene films fabricated by Physical Vapor Deposition and possible implications for electronic devices

Organic thin films have been used as active layers and are an alternative to inorganic materials in order to improve the performance of electronic devices. Recently, Dinaphtho[2,3-b:2′,3′-f]thieno[3,2-b]thiophene (DNTT) became an important compound in organic electronics due to its optical and electrical properties, which are dependent on the supramolecular arrangement. Thus, in this work we determined the supramolecular arrangement of organic thin films of DNTT (DNTT PVD films) fabricated by Physical Vapor Deposition (PVD). Ultraviolet-visible absorption spectra showed the controlled growth of the films within the range from 17 to 120 nm and the formation of aggregates (J- and H-), as the H-aggregate was favored by the thickness. The emission spectra revealed that excimers are responsible for the emission in DNTT PVD films and the increase in solution concentration led to the formation of H-aggregates primarily. The molecular organization of the films, determined by selection rules of Fourier Transform Infrared absorption spectroscopy, suggested that the molecules had a preferential chain-on organization for 120 nm thickness film. Complementary, X-Ray Diffraction data showed that DNTT PVD film was practically monocrystalline with monoclinic cell unit, also determined for the 120 nm thickness film. Atomic Force Microscopy measurements revealed that DNTT film had a homogeneous surface (roughness around 6 nm for the film with 120 nm thickness) with grains of uniform size and geometry. Thus, based on the characteristics of the supramolecular arrangement (especially the molecular organization and increase of H-aggregates with the thickness of DNTT PVD film and the results found in the literature), it was possible to analyze probable implications of chain-on molecular organization and the increase of H-aggregates with the film thickness on the mobility of charge carriers of devices, such as diodes and transistors, in which they are applied.

Research on the removal of Cr(VI) ions from wastewater by Mg/Al-layered double oxides

Cr(VI) is a common pollutant in wastewater that poses a threat to human health and wellbeing. Layered double hydroxides (LDHs) have been identified as an effective physical adsorbent due to their strong anion exchange capacity and memory effect. This work found that calcined Mg/Al-LDHs can effectively remove Cr(VI) ions from wastewater. The adsorption capacity of Mg/Al- layered double oxides (LDOs) for Cr(VI) ions was tested under varying temperature conditions, and the results were found to conform to the Langmuir isotherm model. The maximum adsorption capacity of Mg/Al-LDOs for Cr(VI) ions was 147.39 mg/g at 20 °C. The crystal plane spacing and microscopic morphology of Mg/Al-LDHs before and after the adsorption of Cr(VI) ions were analyzed using a X-ray diffractometer, high-resolution transmission electron microscopy and selected area electron diffraction, and their microstructures were analyzed by Fourier transformation infrared absorption spectroscopy and X-ray photoelectron spectroscopy. The results showed that the adsorption of Cr(VI) ions by Mg/Al-LDOs can be divided into two processes at 20 °C. The first process was the recovery of the single-crystal structure of Mg/Al-LDHs by the adsorption of Cr(VI) ions by Mg/Al-LDOs, and the adsorption capacity of Cr(VI) ions in this process was limited due to the restricted layer spacing in the single-crystal structure. The second process was that the recovered Mg/Al-LDHs single-crystal structure continued to adsorb Cr(VI) ions and grew into a nanoflower-like compound with a polycrystalline structure, and this process led to an increase in the layer spacing of Mg/Al-LDHs, greatly increasing the interlayer Cr(VI) ions adsorption capacity. Additionally, the adsorption of Cr(VI) ions by Mg/Al-LDOs was accompanied by the conversion of Cr(VI) ions to Cr(III) ions at 20 °C, and Cr(III) ions could enter the plate structure to form the Mg/Al/Cr-LDHs structure, which further improved the adsorption capacity and efficiency for interlayer Cr(VI) ions.

Preparation and fire extinguishing mechanism of core-shell solid-liquid composite powder containing ammonium dihydrogen phosphate

A solid-liquid composite powder containing core-shell structure is created under the guidance of theoretical level. Among them, the factors affecting preparation are attributed to stirring speed, solid-liquid mass ratio, stirring time and additive concentration. The results of reduced-size fire chamber indicate that the core-shell structured powder containing NH4H2PO4 (WS-2) can suppress diesel flame more effectively than commercial dry powder (CDP) and common core-shell structured powder (WS-1). Besides, WS-2 shows the highest degree of temperature drop, which is 21.14% and 39.82% higher than CDP and WS-1, respectively. Combined with the results of Thermogravimetric analyzer (TGA) and Fourier transform infrared absorption spectroscopy (FTIR), it can be inferred that WS-2 fully embodies multiple inhibitory effects such as isolation, cooling, asphyxiation and chemical suppression. Ultimately, the excellent fire extinguishing performance brought by its unique structure is demonstrated. This study is of great significance for the determination of technological parameters and application of core-shell powders.

Properties and Emissions of Three-Layer Particleboards Manufactured with Mixtures of Wood Chips and Partially Liquefied Bark.

Partial liquefaction of residual biomass shows good potential for developing new materials suitable for making bio-based composites. Three-layer particleboards were produced by replacing virgin wood particles with partially liquefied bark (PLB) in the core or surface layers. PLB was prepared by the acid-catalyzed liquefaction of industrial bark residues in polyhydric alcohol. The chemical and microscopic structure of bark and residues after liquefaction were evaluated by means of Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM), while the particleboards were tested for their mechanical and water-related properties, as well as their emission profiles. Through a partial liquefaction process, some FTIR absorption peaks of the bark residues were lower than those of raw bark, indicating hydrolysis of chemical compounds. The surface morphology of bark did not change considerably after partial liquefaction. Particleboards with PLB in the core layers showed overall lower densities and mechanical properties (modulus of elasticity, modulus of rupture, and internal bond strength), and were less water-resistant as compared to the ones with PLB used in the surface layers. Formaldehyde emissions from the particleboards were 0.284-0.382 mg/m2·h, and thus, below the E1 class limit required by European Standard EN 13986:2004. The major emissions of volatile organic compounds (VOCs) were carboxylic acids as oxidization and degradation products from hemicelluloses and lignin. The application of PLB in three-layer particleboards is more challenging than in single-layer boards as PLB has different effects on the core and surface layers.

Investigation of Hydration States of Ionic Liquids by Fourier Transform Infrared Absorption Spectroscopy: Relevance to Stabilization of Protein Molecules.

Among many kinds of ionic liquids, some hydrated ionic liquids (Hy ILs) have shown an exceptional capability to stabilize protein molecules and maintain their structure and functions over a long period. However, the complex IL-water interaction among these protein-stabilizing Hy ILs has yet to be elucidated clearly. In this work, we investigate the origin of the compatibility of ionic liquid with proteins from the viewpoint of hydration structure. We systematically analyzed the hydrogen-bonding state of water molecules around ionic liquid using Fourier transform infrared absorption (FT-IR) spectroscopy. We found that the native hydrogen-bonding network of water remained relatively unperturbed in the protein-stabilizing ILs. We also observed that the protein-stabilizing ILs have a strong electric field interaction with the surrounding water molecules and this water-IL interaction did not disrupt the water-water hydrogen-bonding interaction. On the other hand, protein-denaturing ILs perturb the hydrogen-bonding network of the water molecules to a greater extent. Furthermore, the protein-denaturing ILs were found to have a weak electric field effect on the water molecules. We speculate that the direct hydrogen bonding of the ILs with water molecules and the strong electric field of the ions lasting several hydration shells while maintaining the relatively unperturbed hydrogen-bonding network of the water molecules play an essential role in protein stabilization.

Hydrothermal Synthesis and Properties of Nanostructured Silica Containing Lanthanide Type Ln-SiO2 (Ln = La, Ce, Pr, Nd, Eu, Gd, Dy, Yb, Lu).

The nanostructured lanthanide-silica materials of the Ln-SiO2 type (Ln = La, Ce, Pr, Nd, Eu, Gd, Dy, Yb, Lu) were synthesized by the hydrothermal method at 100 °C, using cetyltrimethylammonium as a structural template, silica gel and sodium silicate as a source of silicon, and lanthanide oxides, with Si/Ln molar ratio = 50. The resulting materials were calcined at 500 °C using nitrogen and air, and characterized by X-ray diffraction (XRD), Fourier-Transform infrared absorption spectroscopy, scanning electron microscopy, thermogravimetry (TG), surface area by the BET method and acidity measurements by n-butylamine adsorption. The XRD and chemical analysis indicated that the SiO2 presented a hexagonal structure and the incorporation of lanthanides in the structure changes the properties of the Ln-SiO2 materials. The heavier the lanthanide element, the higher the Si/Ln ratio. The TG curves showed that the decomposition of the structural template occurs in the materials at temperatures below 500 °C. The samples showed variations in specific surface area, mean pore diameter and silica wall thickness, depending on the nature of the lanthanide. The incorporation of different lanthanides in the silica generated acid sites of varied strength. The hydrothermal stability of the Ln-SiO2 materials evaluated at high temperatures, evidenced that the properties can be controlled for application in adsorption and catalysis processes.

Ion Exchange Properties of Crosslinked and Carboxylated Peanut (Arachis Hypogaea L.) Testa Extract

After polymerization via polycondensation of catechin units in the acetone extract of peanut (arachis hypogaea L.) testa (PTE) using phosphorus oxychloride (POCl3) as a crosslinking agent, POCl3-crosslinked PTE (Crosslinked-PPTE) was functionalized by etherification (PC-PTE) using monochloroacetic acid (MCAA) in the presence of an alkali according to the method of Williamson ether synthesis. Subsequent to characterization by Fourier Transform Infrared spectroscopy (FTIR) as well as physical properties, Crosslinked-PPTE was assessed for cation exchange capacity (CEC) and pH at point of zero charge (ZPHC) following demonstrated capacity to remove heavy metal ions in single and multi-elements aqueous solutions by Atomic Absorption Spectrometry (AAS) technique while functionalized (carboxymethylated) Crosslinked-PPTE (PC-PTE) was further characterized by degree of substitution (DS). FTIR absorption bands due to -C-O-P=O, -P=O, P-O-C- and R-O-P-OH stretching vibrations were seen at 1350/1250, 1244/1246, 997/993 cm-1 respectively. Asymmetric and symmetric stretching vibrations of the -C=O of a COOH, Ar-O-C- of an aromatic ether as well as -P-O-C - of an aromatic PO43-, R-P=O of a -PO43-, -R-O-P- and R-O-P-OH of a PO43- ester created by crosslinked and carboxymethylated PTE respectively were seen at 1743, 1377, 1278, 1190, 1062 and 823 cm-1. The results obtained showed that 0.6 was the DS of PC-PTE while 6.72 meq/g and 3.57 defined the CEC and pH (zpc) respectively of Crosslinked-PPTE. Quantitative removal of Fe2+, Ni2+, Pb2+, Cu2+ and Zn2+ in laboratory simulated metal ion wastewater (LSW) to the levels of 84.4, 81.7, 76.5, 72.0 and 75.1% respectively was achieved using Crosslinked-PPTE resin in batch adsorption experiments in which the efficiency was found to depend significantly on the temperature and pH of the water as well as initial adsorbate concentration and contact time but partially on the amount of adsorbent used was observed to be independent of the speed of stirring of the wastewater. Stable, Matakana and fine powder crosslinked-PPTE which is insoluble in water and common laboratory solvents holds great potential in the purification of heavy metal ions polluted water