Fourier Transform Infrared Spectroscopy Results Research Articles

Analysis of the effect of heating rate on pyrolysis kinetics and product composition of copper-containing waste circuit boards.

Pyrolysis is a cost-effective and environmentally benign method for recycling organic waste, which can be converted into high-energy gases and oils. Pyrolysis technology was employed in this study to recycle copper-containing discarded circuit board material and recover copper, glass fibers, and gases and oils with high calorific values. Thermogravimetric analyses (TGA), Fourier transform infrared spectroscopy (FTIR), and gas chromatography-mass spectrometry (GC-MS) were used to evaluate pyrolyses of copper-containing waste circuit board materials conducted at different heating rates (5, 10, 20, and 40°C/min), and the resulting volatiles were studied in detail. The effects of heating rate on the kinetics and activation energies for pyrolyses of copper-containing waste circuit boards were also investigated by using the Coats-Redfern (C-R) method. The TGA curves and FTIR spectra did not differ significantly for different heating rates, and the main functional groups identified with the FTIR results were O-H, C = C, aromatic benzene, substituted benzene, and C-Br. Additionally, GC-MS analyses showed that the heating rate had a great influence on the pyrolysis products formed; the phenol content decreased with increasing heating rate, and the highest content was realized at 5 ℃/min. Energy dispersive spectroscopy (EDS) analyses showed that bromine was removed from the solid phase products during pyrolysis, while copper was effectively enriched in the feedstock. This indicated that pyrolysis can be used to recover copper-containing waste circuit boards.

Effect of Nanocellulose Types on Microporous Acrylic Acid/Sodium Alginate Super Absorbent Polymers.

The aim of this study was to investigate the effect of different types of nanocellulose, i.e., cellulose nanocrystal (CNC), cellulose nanofiber (CNF) and bacterial nanocellulose (BNC), and also different drying methods (oven-drying and freeze-drying) on the properties of acrylic acid (AA)/sodium alginate (SA) super absorbent polymers (SAPs). In addition, the presence of ammonium per sulfate as an initiator and N-N methylene-bis-acrylamide as a cross-linker were considered. Synthesized SAPs were characterized by Fourier transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM). The absorption and rheological properties (i.e., storage modulus and loss modulus) were also investigated. The results of FTIR spectroscopy demonstrated several types of interactions, such as hydrogen and esterification, between SA, AA and nanocellulose. SEM analysis revealed a microporous structure in the SAPs. All SAPs had a centrifuge retention capacity (CRC)/free swelling capacity (FSC) ≥ 69%. The absorption behavior showed that the oven-dried SAPs had superior (about 2×) CRC and FRC in different aqueous media compared to the freeze-dried counterparts. The freeze-dried SAPs showed increased rheological properties in comparison to the oven-dried ones, with SAPs containing BNC and CNC having the highest rheological properties, respectively. Overall, it can be concluded that oven-dried SAPs containing CNC had better absorption properties than the other ones tested in this study.

Solvent extraction of Amla (Phyllanthus emblica) seed oil using hexane

This study investigated the effect of extraction time on yield, phytochemical content in the form of phenolic and flavonoid compounds, and functional groups contained in amla seed oil extract. The research was conducted by extraction using hexane solvent equipped with a stirrer at a speed of 400 rpm at 60 °C for 30 and 120 minutes. The results showed that the extraction time affected the yield of amla seed oil. The highest yield was obtained by using an extraction time of 120 minutes. It can be proven by the morphological structure analysis using scanning electron microscope. Phytochemical analysis showed amla seed oil has high phenolic and flavonoid compounds at the extraction time of 120 minutes compared than 30 minutes. The results of FTIR (Fourier Transform Infrared Spectroscopy) of amla seed oil with different extraction times showed the same functional group content in the form of a hydroxyl group (O-H) indicating the presence of polyphenolic compounds, a ketone group (C=O) indicating the presence of ascorbic acid compounds and an ether group (C-O) indicating the presence of ascorbic acid the presence of flavonoid compounds in amla seed oil.

Controlled Drug Release and Antibacterial Properties of Levofloxacin-Loaded Silk/Chitosan Green Composite for Wound Dressing

Antibacterial wound dressings have great importance to reduce wound infections caused by bacteria. In this research work, levofloxacin-loaded silk fibroin and chitosan composite scaffolds were synthesized for effective wound dressing applications. Initially, silk was degummed for extraction of silk fibroin, and it was mixed with chitosan at different ratios. The chitosan and silk fibroin were stirred at room temperature to get soluble and clear gel formation. Afterward, citric acid was poured into the solution and stirred for more 30 min to get a homogeneous solution. The chitosan and silk fibroin composite was dried using a vacuum oven at 40 °C for 48 h. Next, the composite was loaded with levofloxacin HCL for 24 h at room temperature. The prepared composite was characterized by scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), and fourier transform infrared (FTIR) spectroscopy. The antibacterial activity of prepared scaffolds was evaluated by the agar disc diffusion method. The results of FTIR spectroscopy proved that citric acid cross-linked the cross-linked silk fibroin with chitosan. SEM and EDX spectroscopy demonstrated successful loading of levofloxacin onto scaffolds. Moreover, the levofloxacin-loaded scaffold samples confirmed sustained drug release and antibacterial properties. All results demonstrated that the composite scaffolds using silk fibroin and chitosan with an appropriate antibacterial agent could effectively inhibit the growth of bacteria.

Mussel-inspired polydopamine functionalized with ionic liquid as a novel, eco-efficient adsorbent for the selective removal of anionic pollutants from aqueous solutions

In this work, novel mussel-inspired polydopamine nanoparticles functionalized with ionic liquid (PDA-IL) were synthesized via one step oxidative polymerization and Schiff-base addition reaction using dopamine and ionic liquid (3-aminopropylammonium acetate). The synthesized polydopamine-ionic liquid (PDA-IL) was utilized as an efficient adsorbent in the removal of anionic dyes from aqueous solutions, using Alizarin Red S (ARS) as a model pollutant. Multiple analytical tools, including scanning electron microscopy (SEM), energy-dispersive X-ray (EDX), transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analyzer (TGA), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy and Zeta potential were applied in the characterizations of PDA-IL. A parametric study was conducted to examine the effects of pH, contact time, initial concentration, adsorbent dose, and temperature on PDA-IL adsorption performance. Characterization results confirmed the formation of nano-sized PDA-IL particles with polycrystalline structure. Additionally, the porous structure, surface charge, surface moieties and thermal stability were progressively tuned along with the introduction of the custom-synthesized IL within the matrix of PDA. Results showed a significant maximum ARS adsorption capacity of PDA-IL, up to 234.2 mg g−1 at 25 °C. Adsorption kinetics data revealed a pseudo-second-order kinetics, governed by chemisorption. Equilibrium data for ARS removal were in agreement with Freundlich isotherm, indicating multilayer adsorption on the heterogeneous PDA-IL surface. Furthermore, regeneration studies demonstrated an efficient re-use of PDA-IL adsorbent in at least 4 adsorption/desorption cycles. A selectivity study was also conducted, which showed that PDA-IL selectivity towards anionic dyes can be tuned via pH control. Finally, an adsorption mechanism was proposed, based on FTIR and electron energy loss spectroscopy (EELS) mapping results, among others, for an understanding of the underlying adsorption phenomena on PDA-IL. Overall, the developed PDA-IL adsorbent had a great removal capacity of anionic ARS dye, fast adsorption kinetics, excellent selectivity towards anionic dyes and high regeneration efficiency.

Isolation of Cellulosic Nano Fibers from Delonix Regia Fruits by Mechano-chemical Route

Lignocellulosic fibres have acquired prominence over past few years among researchers due to its prevalence in nature, biodegradability and high specific strength, among other factors. In this paper, mechanochemical route is used to obtain cellulosic nano fibres (CNF) from raw Delonix Regia fruits. CNFs are extracted with chemical treatments including alkali treatment, bleaching, acid hydrolysis and mechanical treatment including ball milling, centrifugation and high speed homogenization. Characterization of the material produced is carried out using X-Ray Diffraction (XRD), Thermo-Gravimetric Analysis (TGA), Fourier Transform Infrared Spectroscopy (FTIR) and Nano Particle Size Analyzer (NPA). XRD results showed that the crystallinity index (CrI) improved from 52.24% to 73.59% for extracted cellulose whereas it got reduced slightly to 68.31% for CNF samples and the crystallite size extracted cellulose and CNF was estimated to be 6.9 nm and 5.1 nm respectively. TGA results proved that the extracted cellulose and CNF are thermally stable compared to raw DRFF samples. First degradation in TGA started near 70-80C which represents moisture loss. Second degradation temperature improved for cellulose and CNF from 173.6C for DRFF to 223.4C and 246.1C which showed improvement in thermal stability. Major weight loss in second degradation shifted from 298.3C to 346.8C and 348.5C for cellulose and CNF respectively. Ash content was slightly decreased for CNF and cellulose samples compared to DRFF. Typical characteristic IR bands of cellulose were observed at 3400 cm-1, 2800-2900 cm-1, 1643.6 cm-1,1447 cm-1, 1084.6 cm-1 and 673.8 cm-1 of O-H stretching vibrations, C-H stretching, O-H bending, CH2 bending of pyranose ring, C-O-C pyranose ring vibration and O-H out-of-plane bending respectively in extracted cellulose and CNF samples. Improvement in cellulose content was observed from FTIR results and found suitable for application in composite materials. The average particle size of CNF measured by NPA was 247.3 nm proving the abundance of material at nanoscale. The average zeta potential of CNF was estimated at -50 mV with negative sign representing hydroxyl group. From the results of zeta potential measurement, material was found to be electro-statically stable and can be utilized for nanocomposite fabrication.

An investigation on demineralization induced modifications in the macromolecular structure and its influence on the thermal behavior of coking and non-coking coal

Eight coking and non-coking coals have been studied by Wide Angle X-ray Scattering (WAXS), Fourier Transform Infrared Spectroscopy (FTIR), and TG/DTG (Thermogravimetry/Derivative Thermogravimetry) – DSC (Differential Scanning Calorimeter). The FTIR study shows that the demineralization treatment significantly influences –OH, aliphatic (–CH3, –CH2), aromatic (C=O), and aromatic nucleus (C=C) functional groups of the raw coals. The structural parameters like interlayer spacing (d002), crystallite size (Lc), lateral size (La), aromaticity (fa)XRD, and rank (I26/I20) are determined from WAXS. The WAXS results of demineralized coal show that d002 (range 3.75–3.51 Å) decreases, but (fa)XRD (range 0.69–0.88) increases with the increase of elemental carbon percentage (Cdaf) and rank of coals. The combustion and kinetic parameters of these coals have been evaluated by TG/DTG – DSC analysis. The ignition temperature (Ti), DTG Tpeak, DSC Tpeak, and burnout temperature (Tb) vary in the range of 338–410 °C, 475–551 °C, 490–555 °C, and 579–641 °C, respectively for demineralized coals however variations of these parameters for raw coals are 345–361 °C, 462–621 °C, 467–631 °C, and 560–675 °C, respectively. The TG/DTG – DSC and FTIR results show that demineralization influences the thermal behaviors and functional groups vis-à-vis structural moieties of coals.

Multivariate Data Analysis and Central Composite Design-Oriented Optimization of Solid Carriers for Formulation of Curcumin-Loaded Solid SNEDDS: Dissolution and Bioavailability Assessment.

The study was initiated with two major purposes: investigating the role of isomalt (GIQ9) as a pharmaceutical carrier for solid self-nanoemulsifying drug delivery systems (S-SNEDDSs) and improving the oral bioavailability of lipophilic curcumin (CUN). GIQ9 has never been explored for solidification of liquid lipid-based nanoparticles such as a liquid isotropic mixture of a SNEDDS containing oil, surfactant and co-surfactant. The suitability of GIQ9 as a carrier was assessed by calculating the loading factor, flow and micromeritic properties. The S-SNEDDSs were prepared by surface adsorption technique. The formulation variables were optimized using central composite design (CCD). The optimized S-SNEDDS was evaluated for differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), microscopy, dissolution and pharmacokinetic studies. The S-SNEDDS showed a particle size, zeta potential and PDI of 97 nm, -26.8 mV and 0.354, respectively. The results of DSC, XRD, FTIR and microscopic studies revealed that the isotropic mixture was adsorbed onto the solid carrier. The L-SNEDDS and S-SNEDDS showed no significant difference in drug release, indicating no change upon solidification. The optimized S-SNEDDS showed 5.1-fold and 61.7-fold enhancement in dissolution rate and oral bioavailability as compared to the naïve curcumin. The overall outcomes of the study indicated the suitability of GIQ9 as a solid carrier for SNEDDSs.

The influence of calcium chloride concentration on the mechanical and barrier properties of high amylose corn starch film

In this study, high amylose corn starch (HACS) films were prepared using CaCl2 as cosolvent. The interaction between CaCl2 and HACS during the preparation was investigated. Differences in physicochemical properties between HACS films with and without CaCl2 were characterized using wide-angle X-ray diffractometer (XRD), Fourier transform infrared spectroscopy (FTIR), water vapor permeability (WVP), thermogravimetric analysis (TG) and atomic force microscopy (AFM). The tensile strength and elongation at break increased to 27.01 ± 1.13 MPa and 17.4 ± 1.9%, respectively, CaCl2 had plasticizing effect and provided mechanical reinforcement to the formed HACS films. The reinforcement was mainly due to (ⅰ) CaCl2 increased the content of free amylose chains in the aqueous phase, and (ⅱ) chelation between Ca2+ and starch chains enhanced the entanglement between HACS chains. The results of XRD and FTIR indicated the crystalline region and shot-range orderliness of films decreased, CaCl2 significantly increased the dispersion of starch chains and made the HACS films more homogeneous. CaCl2 improved the barrier properties and surface morphology. The surface roughness of the HACS films decreased fromRa = 189 nm, Rq = 242 nm toRa = 103 nm, Rq = 152 nm as the concentration of CaCl2 increased. However, high concentration of CaCl2 destroyed the inner and surface structure of the film to some extent.

Nitrite Removal from Lake Urmia Sediments Using Biohydrogel Based on Isolated Soy Protein/Tragacanth/ Mesoporous Silica Nanoparticles

Lake Urmia is one of the largest saltwater lakes in the world. In recent years, due to the drought conditions and the uncontrolled entry of industrial wastewater into the lake, the amount of some chemical pollutants has been increased dramatically in lake sediments. The most important pollutants in the lake are chemical organic compounds, heavy metals, nitrate, nitrite, among which, nitrite pollution is very important. The aim of this study was to prepare and asses the efficiency of a biodegradable biohydrogel based on isolated soy protein/tragacanth containing mesoporous silica nanoparticles and lycopene pigment (ISP/ TG/MPS/Lyc) in removal of the nitrite from the Lake sediments. The physicochemical characteristics and structure of the biohydrogel are investigated by scanning electron microscopy, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, and thermal gravimetry analysis (TGA) techniques. Five optimal biohydrogels including pure ISP, ISP/TG, ISP/MPS, ISP/Lyc, and ISP/ TG/MPS/Lyc are used for chemical treatment of Lake Urmia sediments. For this purpose, biochemical oxygen demand (BOD), chemical oxygen demand (COD), and nitrite of sediments are examined before and after treatment with biohydrogels. According to the FTIR results, there is only physical interaction between lycopene and isolated soy protein. According to the TGA results, adding silica mesoporous to biohydrogel increases its thermal stability. Tragacanth gum and lycopene pigment reduce water solubility and increase the WAC of biohydrogel. The biohydrogel significantly reduces the BOD and COD of the sediments. The biohydrogel reduces nitrite content up to 90%, while reducing nitrate content by almost 30%. The results show that the biohydrogel containing lycopene selectively purifies nitrite from the sediment solution of Lake Urmia.

Characteristics of diamond crystals from FeNiCo-C system with Ge doping under high pressure and high temperature

Various optical color centers in natural and synthetic diamond have attractive great attention of researched; to further investigate the effects of additive on diamond properties is of practical significance. In this work, diamond crystallization was investigated by temperature gradient growth method with Ge additive at a set pressure of 6.5 GPa and synthesis temperature ranging from 1290 to 1310 °C. Scanning electron microscope (SEM), and spectral characterization including Fourier transform infrared spectroscopy (FTIR) and photoluminescence (PL) spectra were used to investigate the surface growth mechanism of diamond. It was noticed that the visible inclusions gradually reduced in the as-grown diamond, accompanying with the increase of Ge additive in the synthesis cavity. The (111) surface of the synthesized diamond followed the layer growth pattern from the SEM results. According to the measured FTIR results, the nitrogen impurity concentration values of the synthesized diamond crystals decreased from 500 to 90 ppm, confirming that Ge showed its own ability to remove nitrogen impurity in the growth stage of diamond. Additionally, the nickel-related and nitrogen-related optical color centers of the obtained diamond were characterized by PL spectra. Characteristic peaks due to nickel-related optical color centers located at 515 or 535 nm, and Characteristic peaks attributing to nitrogen-related optical color centers located at 575 or 637 nm. We believe that the research is of great significance for the application of diamond in optical and quantum information science fields.

Depth of Cure, Mechanical Properties and Morphology of Dual-Cure Bulk-Fill Composites

This study evaluated selected structural and physical properties, such as degree of conversion (DC), Vickers hardness (VHN), and compression strength (CS), of three new dual-cure bulk-fill resin-based composites (RBCs; ACTIVA, HyperFIL, and Fill-Up) and compared them to those of a conventional RBC (Filtek Z250) at three clinically relevant depths. Samples (n=180) were prepared in three depths (2,4, and 6mm). Fourier-transform infrared spectroscopy (FTIR) analysis and VHN and CS tests were performed. The DC value was calculated by considering the relative change in the aliphatic C=C peaks. The fractured surfaces of representative samples were characterized using scanning electron microscopy (SEM). Data were statistically evaluated using two-way analysis of variance and post hoc Bonferroni tests (p<0.05). According to the VHN results, Filtek Z250 showed the highest bottom/top hardness ratio (97.94±1.01) at 2mm thickness and ACTIVA showed the lowest bottom/top hardness ratio (43.48±5.64) at 6mm thickness (p<0.001). According to the FTIR results, the DC decreased with increasing thickness in all materials (p<0.05). Filtek Z250 showed the highest (301±12.4 MPa) and ACTIVA exhibited the lowest (232±17.2 MPa) CS values at 2mm thickness (p<0.05). The lowest CS values were obtained for ACTIVA, and the highest values were obtained for Filtek Z250 for samples with thicknesses of 4 and 6mm, respectively (p<0.05). The structural features of restorative composites, such as the resin chemistry and filler type and content, and the operational parameters (i.e., material thickness and curing conditions) strongly affect crosslinking reactions and thus the DC, VHN, and CS values.

Physical Properties of Fast-Growing Wood-Polymer Nano Composite Synthesized through TiO2 Nanoparticle Impregnation.

Mangium (Acacia mangium Willd.) is a fast-growing wood that is widely grown in Indonesia. The impregnation method is needed to improve the qualities of the wood. In this study, TiO2 nanoparticle (79.17 nm) was produced using the hydrothermal method. The purpose of this study was to analyze the effect of TiO2 nanoparticle impregnation on the density and dimensional stability of mangium and the effectiveness of the presence of TiO2 nanoparticle in wood in degrading pollutants. The mangium samples (2 cm × 2 cm × 2 cm) were placed inside impregnation tube. The impregnation solutions included water (untreated), 1% TiO2 nanoparticle, and 5% TiO2 nanoparticles. The samples were analyzed for density, weight percent gain (WPG) dan bulking effect (BE). Samples were also analyzed by X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). TiO2 nanoparticle resulted in an increase in density, WPG, and BE-treated mangium. Based on XRD and FTIR results, TiO2 nanoparticle was successfully impregnated into mangium wood. Scanning electron microscopy–energy-dispersive X-ray spectroscopy analysis indicated that TiO2 nanoparticle covered the surface of the wood cells. The TiO2-impregnated mangium wood has a higher photocatalyst activity than untreated, indicating better protection from UV radiation and pollutants.

Succeeded high-temperature acid hydrolysis of granular maize starch by introducing heat-moisture pre-treatment

Acid hydrolysis is a crucial method for modifying granular starch, but it is often conducted at low temperatures (below 55 °C) for an extended period of time to prevent crystallinity loss. The high-temperature acid hydrolysis (HTAH) behavior of heat-moisture treated (HMT) starch at 69 °C was investigated for the first time. The crystalline structure of starch was enhanced by HMT, confirmed by its rheological, thermal, and infrared Fourier transform spectroscopy results. The amorphous structure of HMT starch was preferentially hydrolyzed with high reactivity, related to a fast hydrolysis stage (4.17 × 10−2 min−1). And the crystalline flakes were separated from starch granules, accompanied by strengthened molecular interactions. HMT starch was transformed from 16.98 μm granules to 158 nm thick and 2.57 μm broad flakes with a 6.40 % increase in crystallinity after 40 min of hydrolysis. For native starch, the HTAH destroyed the crystalline structure due to gelatinization, resulting mainly gelatinous aggregates. These evidenced that the hydrolysis of granular starch was successfully performed at a relatively high temperature by introducing heat-moisture pre-treatment. This study could provide a novel perspective on the combination of increasing temperature and pre-treatment for granular starch hydrolysis intensification design, as well as a strategy for efficiently preparing small-sized crystalline starch, which has promising applications in Pickering emulsion and material filler.

Activation of zirconia nanophosphors with Eu3+ to demonstrate multifunctional optical applications

Pristine ZrO2 and Eu3+ activated ZrO2 nanophosphors were synthesized by urea assisted solution combustion method. The synthesized nanophosphors were characterized by Powder X-ray diffraction (PXRD), Field emission scanning electron microscopy (FESEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), and photoluminescent (PL) spectroscopy for their structural, morphological, surface, vibrational and luminescent studies. The crystal structure and phase transformation were studied by PXRD which was supported well by XPS and FTIR results. FESEM studies reveal the porous morphology due to the combustion synthesis. XPS results reveal that activator Eu was predominantly present in the +3 oxidation state in the nanpohosphor. PL emission spectra of Eu3+ activated zirconia show characteristic reddish emission corresponding to 5D0→7FJ (J = 0, 1, 2, 3, and 4) transitions of Eu3+ ion. Photometric parameters were calculated to check the possible application of the nanophosphors for solid-state lighting. The high color purity ∼94% of the synthesized phosphors indicates their application in phosphor-converted white light-emitting diodes (pc-wLEDs). The fluorescence intensity ratio (FIR) of non-thermally coupled levels 5D0→7F2 and 5D0→7F3 were used to calculate the temperature. At 623 K, a maximum relative and absolute sensitivity of 0.11% K−1, and 0.76% K−1 was observed. The possible anti-counterfeiting application of ZrO2:Eu3+ has been tested using a standard screen-printing procedure. The high contrast fingerprints of the synthesized phosphor taken under near-ultraviolet (n-UV) light indicate that the synthesized phosphor can be used for latent fingerprinting applications. All these results indicate that Eu3+ activated zirconia has the potential to be used as multifunctional material.

Amine‐modified graphene enhanced mechanical properties and catalytic effect on imidization of polyimide composite films

AbstractThe degree of the imidization reaction determines the properties of polyimide (PI) obtained by the thermal curing process. In this paper, amine‐modified graphene (N‐GO) was designed by integrating pyridine structure with graphene and acting as a catalyst to promote the imidization reaction of PI. Fourier‐transform infrared spectroscopy (FTIR), scanning electron microscope (SEM) were then used to confirm the morphology and structure of N‐GO. The catalytic effect of N‐GO in imidization reaction was obtained by FTIR and subsequently characterized by differential scanning calorimetry (DSC) and water contact angle (WCA). Surprising results suggest that the agglomeration of N‐GO can also contribute to solid‐phase reactions in imidization reactions. Lastly, the results of mechanical property tests, thermogravimetric analysis (TGA), and FTIR demonstrated that the composite films showed excellent tensile strength (176.2 MPa) and thermal stability (513.0 °C); at the same content, only 0.5% of N‐GO addition reduced the imidization temperature by 20°C, exhibiting remarkable enhancement effects. This research is a valuable solution to the problem in performance caused by low‐temperature curing agent residues in films, and it is expected to be used in the microelectronics field.

"One-pot" preparation of aminated carbon nanotube-modified magnetic nanoparticles and their application to the quantification of phenoxyacetic acid herbicides in cereal and vegetable samples

有效萃取是分析复杂样品中苯氧羧酸类除草剂(PAs)残留的关键步骤。为此,该文利用“一锅法”水热技术快速、简便地制备了氨基碳纳米管功能化磁性纳米粒子(NH2-CNTs@M)并作为磁固相萃取(MSPE)的萃取介质,用于萃取谷物和蔬菜样品中痕量PAs。研究利用多种手段对NH2-CNTs@M的形貌、尺寸、磁性性质等进行了表征,结果表明Fe3O4的粒径、氨基化碳纳米管的直径以及NH2-CNTs@M的磁饱和值分别为30 nm、40 nm和44.2 emu/g。详细考察了制备条件和萃取参数对NH2-CNTs@M/MSPE萃取性能的影响,结果表明,NH2-CNTs@M/MSPE可通过π-π、疏水和氢键作用有效富集目标化合物,最佳萃取条件如下:吸附剂用量为30 mg,解吸溶剂为含2.0%(v/v)甲酸的乙腈溶液,吸附时间和解吸时间分别为8.0 min和3.0 min,基底pH值为6.0,不调节基底的离子强度。将NH2-CNTs@M/MSPE与高效液相色谱-二极管阵列检测技术(HPLC-DAD)联用,建立了谷物和蔬菜中PAs的灵敏检测方法。谷物和蔬菜基质中苯氧羧酸类除草剂的检出限(LOD, S/N=3)分别为0.32~1.6 μg/kg和0.53~1.6 μg/kg,定量限(LOQ, S/N=10)分别为0.94~4.8 μg/kg和1.6~4.8 μg/kg。在两种实际样品中不同浓度下的加标回收率分别为73.1%~112%和72.3%~113%。与现有方法相比,所建方法具有萃取速度快、灵敏度高和环境友好等特点。

Martian and lunar sulfur concrete mechanical and chemical properties considering regolith ingredients and sublimation

• Sulfur sublimation rate at vacuum is 8000 times lower at −60 °C than at 20 °C. • Sulfur concrete permeability decreases strongly with higher sulfur content. • Sulfur concrete porosity does not change much with varying sulfur content. • The presence of alumina in sulphur concrete results in higher porosity. • Alumina and iron oxide together in sulphur concrete leads to lower porosity. Space constructions require unique materials suitable for the harsh conditions in space. Sulfur concrete (SC) is one of the most promising materials for such applications. However, the behavior of sulfur concrete in a vacuum, microgravity, and different temperature conditions and its chemical changes has not been well established yet. This study investigated the effect of vacuum, sulfur content, and compaction (trowel effect) on mechanical and hydro-mechanical properties. Moreover, this study assesses the impact of chemical reactions of aluminum and iron oxides with molten sulfur on the sulfur concrete’s mechanical properties via X-ray diffraction analysis (XRD), scanning electron microscopy (SEM-EDS), and Fourier-transform infrared spectroscopy (FTIR). The predictions from this research show that the sublimation rate under vacuum conditions at very low temperature (−60 °C) can be reduced nearly 8000 times compared with that at 20 °C according to the vapor pressure-sublimation rate relationship. In addition, mechanical experimental tests show that a slight increase in sulfur content dramatically reduces the permeability of sulfur concrete. On the other hand, the porosity is not much affected by the sulfur content. Moreover, sample compaction leads to a significant reduction and increment of the hydro-mechanical and mechanical strength, respectively, indicating the trowel's positive effect. Chemically, sulfur dioxide reacts with alumina and iron oxide via chemical adsorption, and then reaction with molecular oxygen produces S O 4 2 - confirmed by SEM-EDS, XRD, and FTIR results. The presence of alumina increases the sample porosity, although, together with iron oxide, another mineral, namely A l 2 F e 2 S O 4 6 ( H 2 O ) 12 . 6 H 2 O (Aluminocoquimbite), is formed resulting in a lower porosity. To conclude, we have shed light on sulfur concrete properties and preparation processes in unconventional environments and we have shown how different unknown parameters affect the mechanical and chemical properties of the sulfur binder.

Synthesis and characterization of silver-indium and antimony selenide: role in photocatalytic degradation of dyes

These days, water contamination poses a severe threat to the ecosystem and demands immediate care. This study examined the need to reduce water pollution using clean, renewable energy (solar light irradiations) for the degradation of Congo red by Silver-indium and antimony selenide with chemical composition AgInSbSe3. The sample was fabricated through a hydrothermal technique. The synthesized sample was characterized through X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), Scanning electron microscopy (SEM) and Ultraviolet-Visible spectroscopy. The X-ray diffraction confirms crystalline structure of the synthesized sample. The SEM analysis reveals irregular grains and exhibits a very small inter-particle distance. SEM provides the morphology of the synthesized sample, the grain size of the synthesized sample was 0.58 μm. FTIR results revealed specific absorption bands in the range of 400–4000 cm−1; optical properties are studied through UV-Vis-spectroscopy. The synthesized sample has 1.97 eV bandgap which is suitable for degradation of organic pollutants. The photocatalytic activity of the material is checked by degrading the Congo red dye under direct sunlight irradiation and for the 75 min illumination 77.8% degradation efficiency is attained.

Characterization of the mural blue paintings in ornamental motif of Ali Qapu palace in Isfahan, Iran, using spectroscopic and microscopic methods (a case study)

This study aimed to investigate the painting technique and identify the blue pigments used in the ornamental motif of mural paintings of Ali Qapu palace as the seat of rule of Shah Abbas I Safavid and part of Naghsh-e Jahan square world heritage site in Isfahan. For this investigation, five samples collected from the murals located at different sections of the palace were studied by polarized light microscopy (PLM), Fourier-transform infrared spectroscopy (FTIR), Raman spectroscopy, and energy-dispersive X-ray spectroscopy (EDS). Also, the Fourier self-deconvolution was applied to the FTIR spectra of chloroform extract of the paint layer to identify the type of binder used in the painting. The results showed that the blue pigment used in all five samples is natural ultramarine (lapis lazuli). In four of the five samples, huntite has been used as the filler in the priming layer. However, the results suggest that huntite has also been combined with ultramarine to create lighter tonalities. The findings indicate the use of three different priming methods in creating the ornamental motif murals: creating a priming layer with iron-rich soil, creating a priming layer with huntite as the filler, and placing an organic layer underneath the huntite priming layer. This shows the variety of priming techniques used in creating the ornamental motif murals of Ali Qapu. Furthermore, FTIR results indicate the possible use of the tempera and oil technique in the murals.