Fourier Transform Infrared Spectrometer Research Articles

Investigate Performance of ATGF nanocomposite based on guar gum polymer for adsorption of Congo Red dye and alpha lipoic acid drug from wastewater: study kinetics and simulation

AbstractIn this study, the synthesized nanocomposite novel arginine/thiourea/guar gum/ferrite (ATGF) adsorbent was evaluated for the adsorption of alpha lipoic acid (ALA) and Congo Red (CR) from wastewater. The synthesized nanocomposite was examined by Brunauer–Emmett–Teller theory (BET), Termal gravimetric analysis (TGA), Fourier transform infrared spectrometer (FT‐IR), field emission scanning electron microscopy (FE‐SEM), X‐ray Diffraction (XRD), Vibrating sample magnetometer (VSM), and energy dispersive X‐ray (EDX). For the removal of ALA and CR from aqueous solution, the capacity of the nanocomposite was investigated by working on a series of experiments such as the effect of adsorbent dose, initial concentration, contact time, pH and temperature. The adsorption kinetics of these two pollutants were investigated using pseudo‐first‐order and pseudo‐second‐order velocity equations. The nanocomposite kinetics follow pseudo‐second‐order. Langmuir and Freundlich isotherms were investigated. The results show that the Langmuir isotherm model gives the maximum adsorption capacity of ALA as 96.93 mg g−1 and of CR as 229.34 mg g−1 on the nanocomposite. © 2024 Society of Chemical Industry.

Preparation of halogen-free flame retardant curing agent and its application in epoxy resin

9,10-Dihydro-9-oxa-10-phosphaphenanthrene-10-oxide-N-Aminoethylpiperazine (DOPO-AEP), a phosphorus and nitrogen intumescent flame retardant curing agent was prepared by using acetonitrile as solvent using 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and N-aminoethylpiperazine (AEP) as raw materials. The structure of the flame retardant curing agent DOPO-AEP was analyzed Fourier Transform Infrared Spectrometer (FTIR), Nuclear Magnetic Resonance (NMR) and Electrospray Ionization Mass Spectrometry (ESI-MS), and the synthesis method of the target product was determined. In addition, the content of char residue was determined by thermogravimetric analyzer, and its thermal properties were comprehensively explored, and based on the obtained results, the curable epoxy resin was selected to prepare DOPO-AEP/EP flame retardant composites. According to the amount of DOPO-AEP added product, different proportions of DOPO-AEP/EP flame retardant composites were prepared, and the actual impact of flame retardant properties and mechanical properties of epoxy resin in different proportions was explored. When the content of DOPO-AEP is 35%, the limiting oxygen index of DOPO-AEP/EP reaches 29.9, which has a significant increase compared with the limiting oxygen index of pure epoxy resin of 19.8, but compared with the content of DOPO-AEP of 30%, the limiting oxygen index of DOPO-AEP/EP is 28.7, and there is no significant increase change. Comprehensive analysis shows that when the component content of DOPO-AEP is 30%, the flame retardant system has a tensile strength of 29.0 MPa, an impact strength of 4.5Kj/m2 and a flexural strength of 73.9 MPa, and its limiting oxygen index is as high as 28.7, and the comprehensive performance of the system is the best. By testing the surface morphology of the flame retardant composites after combustion by SEM, it was found that a dense char layer was formed on the surface of the epoxy resin cured char residue and foamed obviously, indicating that the flame retardant curing performance of DOPO-AEP was good.

Preparation of Poly(Styrene-co-Acrylonitrile)-Grafted Attapulgite via Simultaneous Reverse and Normal Initiation Atom Transfer Radical Polymerization (SR&NI ATRP) and Its Effect on Polycarbonate/Acrylonitrile-Butadiene-Styrene Terpolymer Ternary Composites

To further improve the comprehensive properties of polycarbonate/acrylonitrile–butadiene–styrene terpolymer blends (PC/ABS), in this work, styrene–acrylonitrile copolymer [P(St-co-An)] was grafted on the surface of attapulgite particles (ATP) by simultaneous reverse and normal initiation ATRP (SR&NI ATRP) to yield ATP@P(St-co-An) hybrid particles. Then a series of PC/ABS/ATP@P(St-co-An) composites were prepared via the melt blending method. The effects of ATP@P(St-co-An) content on the morphological, mechanical, thermal and rheological properties of the composites were investigated in detail. The core-shell ATP@P(St-co-An) hybrid particles with the polymer layer thickness of 20-40 nm were synthesized successfully according to the results of X-ray photoelectron spectrometer (XPS), Fourier transform infrared spectrometer (FTIR), gel permeation chromatography (GPC), thermogravimetric analysis (TGA) and transmission electron microscopy (TEM). The improvement in mechanical properties, reduced glass transition temperature (T g) difference between PC and ABS and micromorphology changes of the composites proved the compatibilization, strengthening, and toughening effect of the ATP@P(St-co-An). Compared with the PC/ABS blend, with strength and toughness of 50.8 MPa and 56.3 kJ/m2, when the ATP@P(St-co-An) content was 4 wt%, a reasonable balance (85.8 MPa and 86.2 kJ/m2) between strength and toughness was achieved with substantially enhanced thermal stability. Moreover, the composite showed more remarkable non-Newtonian behavior, and its processability was also improved. We believe this work provides an effective approach to optimize the compatibility and comprehensive properties of PC/ABS blends.

Ultrasound-assisted extraction of polysaccharides from Ginkgo biloba: Process optimization, composition and anti-inflammatory activity

Plant derived polysaccharides can enhance immune function in the human body, effectively prevent diseases, and reduce the probability of bacterial infections. Ginkgo crude polysaccharide (GCP) was obtained from Ginkgo biloba by ultrasonic-assisted hot water extraction. Our data showed that the best extraction conditions of GCP were as follows: extraction temperature 80 °C, ultrasonic time 35 min, extraction time 3 h, and solid‒liquid ratio 1:30. Fourier transform infrared spectrometer (FT-IR) data showed that this polysaccharide might be an acidic polysaccharide with a carboxylic acid ring structure. Further studies implied that GCP was mainly composed of glucose, galacturonic acid, rhamnose, galactose and arabinose, accounting for 39.45 %, 25.01 %, 15.40 %, 11.94 % and 4.25 %, respectively. 0.1, 1 and 10 mg/mL GCP reduced the release of inflammatory factors in RAW264.7 cells via inhibition of the nuclear factor kappa-light-chain-enhancer of activated B (NF-κB) signalling pathway. GCP was separated into five components with different molecular weights by an ultrafiltration membrane. Our data showed that GPa with a molecular weight ≥100 kDa was the main component of GCP. 1 mg/mL GPa, GPb, GPc and GPd had anti-inflammatory activities, and 1 mg/mL GPa had the best anti-inflammatory activities. Our results preliminarily reveal the elements and biological activity of GCP, which will provide a reference for the development of Ginkgo biloba.

Investigating the impact of different cleaning techniques on bond strength between resin cement and zirconia and the resulting physical and chemical surface alterations.

To evaluate the effect of cleaning methods and thermocycling on the micro-tensile bond strength between resin cement and contaminated zirconia and to characterize the physicochemical alterations at the zirconia surface resulting from contaminants and subsequent application of cleaning methods. Thirty-two alumina air-abraded zirconia blocks were divided into eight groups: (i) uncontaminated control followed by methacryloyloxydecyl dihydrogen phosphate (MDP) primer (G-Multi Primer) application (CON). In groups ii-viii, the blocks were contaminated with saliva and silicone disclosing agents, followed by cleaning as follows: (ii) MDP primer applied, followed by contamination (GMP1); (iii) MDP primer applied before and after contamination (GMP2); (iv) cleaning with alumina air-abrasion (APA); (v) cleaning with sodium hypochlorite (NaOCl); (vi) cleaning with Ivoclean (IVC); (vii) cleaning with ZirClean (ZC); and (viii) cleaning with Katana Cleaner (KC). After cleaning, the zirconia blocks in groups iv-viii were applied with MDP primer. The blocks in each group were cemented together with resin cement (G-Cem Linkforce). Subsequently, each bonded zirconia block was sectioned using a water-cooled diamond saw into microsticks (1×1×9 mm3). Micro-tensile bond strength was measured after either 24h or 10,000 thermal cycles (n = 20/subgroup). Data were analyzed using two-way analysis of variance (ANOVA), followed by one-way ANOVA, and Tukey's post-hoc test. The contact angle measurements, energy dispersive X-ray spectroscopy (EDS), and Fourier-transform infrared (FTIR) spectrometer were used for physiochemical evaluation. After 24h of water storage, the highest bond strength was observed in the CON, NaOCl, APA, and GMP2 groups. After thermocycling, the bond strength significantly decreased in all groups except the GMP2 group, which maintained the highest bond strength. Commercial ceramic cleaning agents (IVC, ZC, and KC groups) exhibited lower bond strengths than the CON groups in both aging conditions. The application of MDP primer before and after contamination is a promising cleaning protocol for removing saliva and silicone disclosing agent contaminants from zirconia surfaces. This approach achieved the highest bond strength and maintained it even after artificial aging through thermocycling.

Corrosion resistance of polymer-modified hardened cement paste and phosphoric acid-activated metakaolin geopolymer in carbonic acid solution

Corrosion resistance of hardened Portland cement paste (HCP), polymer-modified hardened cement paste (PHCP) and phosphoric acid-activated metakaolin (PMK) geopolymers in carbonic acid solution was comparatively evaluated by multiple techniques of thermogravimetry (TG), energy dispersive spectrometer (EDS), fourier transform infrared spectrometer (FTIR), inductively coupled plasma optical spectrometer (ICP), microindentation and compressive tests. The incorporated polymer kinetically slows down the corrosion process of Portland cement paste as the carbonation depth of PHCP is lower than those of HCP characterized by all techniques. Meanwhile, the addition of polymer slightly hinders leaching of substances from HCP by blocking the pores. Despite the increase of elastic modulus, decreases of compressive strength of both HCP and PHCP samples caused by carbonation are observed probably due to the generation of microcracks and uneven brittleness across the section. PHCP presents less mechanical loss after carbonation treatment than HCP. PMK geopolymer samples soaked in deionized water and carbonic acid solution have comparatively identical results of TG, EDS, FTIR and mechanical measurements, indicating that the PMK geopolymer is highly resistant to carbonic acid, thanks to its inherent acidic nature. In addition, the leaching amount of PMK geopolymer in carbonic acid solution is also much less than the HCP and PHCP.

PH and Temperature-Responsive Silk Sericin/N-Isopropyl Acrylamide Interpenetrating Network Gel and Viscose Non-Woven Cross-Linked Composite Dressing

A gel (SNA-Ag) loaded with nanoscale silver particles and a pH-responsive agent was prepared using N-isopropyl acrylamide (NIPAAm) as the first network structure, silk sericin (SS) as the second network structure and reducing agent, alizarin as the pH indicator and co-reducing agent, N, N-methylene bisacrylamide (BIS) as the crosslinking agent, ammonium persulfate (APS) as the initiator and N, N, N, N-tetramethylethylenediamine (TEMED) as co-initiator. To improve the breaking strength of the gel, the temperature and pH-responsive antibacterial (V/SNA-Ag) composite dressing was prepared by crosslinking the SNA-Ag gel with viscose non-woven fabric using glutaraldehyde as the crosslinking agent. Fourier transform infrared spectrometer (FTIR) and scanning electron microscopy (SEM) showed that the SNA-Ag hydrogel was successfully crosslinked with the viscose non-woven fabric. Meanwhile, a gel coating was formed on the fabric, and the coating thickness increased when the crosslinking time was extended. Differential Scanning Calorimetry (DSC) and pH response tests confirmed that the dressing was temperature sensitive, and the Lower Critical Solution Temperature (LCST) of the dressing was about 35 °C. When the pH of the dressing was changed from acidic to alkaline, its color was changed from yellow to purple, indicating that its color presented pH response characteristics. The dressing not only had excellent swelling performance but also had outstanding antibacterial activity; the antibacterial degree for Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) was up to 99%. A cytotoxicity test suggested that the survival degree of mouse cells after incubation for 96 h was more than 75%, proving that it was safe and nontoxic. In addition, compared with viscose non-woven fabric, the breaking strength of composite dressing was increased, and the air permeability was decreased. In conclusion, we suggest that V/SNA-Ag composite dressings have great potential for monitoring and treating wounds.

Microplastics in wild fish in the Three Gorges Reservoir, China: A detailed investigation of their occurrence, characteristics, biomagnification and risk

Microplastics (MPs) pollution in freshwater poses a risk to various ecosystems and health security. In 2018, the Chinese government banned fishing since 2018 in the Three Gorges Reservoir (TGR), but the fate and risk of MPs in wild fish remain unclear. Therefore, a detailed investigation was conducted into the occurrence of MPs in 18 wild fish species in the TGR using a Micro Fourier Transform Infrared Spectrometer, and the trophic transfer and risks were assessed. MPs in fish were aged, with abundances ranging from 0.68 ± 0.98 to 4.00 ± 2.12 items/individual. Most particles were less than 1 mm in size (73.4 %), with fibers being the dominant shape (48.9 %) and transparent as the dominant color (35 %). Polyethylene (PE) was the most prevalent type. The bioconcentration factor (BCF), bioaccumulation factor (BAF), trophic magnification factor (TMF) and polymer hazard index (PHI) were low, suggesting no trophic transfer and a low risk of MPs. The BAF may provide a more reasonable description of the degree of enrichment of MPs, and ‘items/individual’ or ‘g/individual’ can be used to describe MPs concentrations in fish. This study proposes new insights and prospectives that can help researchers better understand MPs enrichment in fish across various trophic levels.

Synthesis and color-tunable emission of ZnGaOx with different cation ratios by a polyacrylamide gel method

ZnGaOx nanoparticles with varied ratios of Zn2+ to Ga3+ were synthesized by a polyacrylamide gel route. The phase purity and structure are confirmed by X-ray diffraction (XRD), Fourier transform infrared spectrometer (FTIR) and X-ray photoelectron spectrometer (XPS). High crystal quality and elemental distribution are determined by transmission electron microscopy (TEM) measurements. The band gaps of the samples ranging from 3.22 to 4.47 eV are estimated by ultraviolet–visible (UV–Vis) diffuse refectance spectroscopy (DRS). Under the excitation of 325 nm laser light, ZnGaOx nanoparticles with the Zn2+/Ga3+ molar ratios of 0.8:2 and 0.7:2 show two emission peaks at 415 and 510 nm. A marked emission band at 695 nm is observed from the samples with Zn2+/Ga3+ molar ratios of 0.6:2, 0.5:2 and 0.4:2. The luminescence mechanism is discussed based on the experimental results. The luminescence color of as-synthesized samples gradually shifts from blue-green to green-yellow region with decreasing Zn2+/Ga3+ ratio. Interestingly, the sample with Zn2+/Ga3+ ratio of 0.7:2 has the CIE chromaticity coordinates of (x = 0.26, y = 0.33) close to the coordinates (x = 0.33, y = 0.33) of pure white light. Together, ZnGaOx phosphors with different emission colors without doping with rare earths have considerable potential applications in tunable light emitting diodes (LEDs) and color display.

Study the influence of Ag+ nanoparticles on the surface of the Sr1-xAgxFeO3-δ perovskite on optical, magnetic and antibacterial properties

Recently, we produced low cost SrFeO3-δ perovskite with antibacterial properties. In this study to improve the antibacterial properties of SrFeO3-δ perovskite, we doped it with silver. Ag+ nanoparticles on the surface of the Sr1-xAgxFeO3-δ perovskite samples were prepared by sol-gel method. Structural properties of these samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), selected area electron diffraction (SAED), high-resolution TEM (HR-TEM), EDS elemental mapping and Fourier transform infrared spectrometer (FT-IR). These techniques confirmed the presence of small amount of cubic Ag spherical nanoparticles on the surface of the cubic Sr1-xAgxFeO3-δ perovskite structure. Further, X-ray photoelectron spectroscopy (XPS) for these samples revealed the presence of Ag1+ ions, oxygen vacancies and mixed valence states of Fe ions on the surface of the samples. The energy band gap of these samples was estimated using Kubelka–Munk equation and its value increased with increasing Ag up to x = 0.10. Additionally, Magnetic hysteresis (M − H) loops revealed that these samples displayed antiferromagnetic behavior with a small amount of ferromagnetic order. Finally, the antibacterial properties of these samples revealed that the antimicrobial activities were improved with increasing Ag (x = 0.10). Our results showed that Ag+ nanoparticles on the surface of the Sr1-xAgxFeO3-δ perovskite samples are a promising antimicrobial agent.Graphical

Investigation of the Thermal and Mechanical Properties of Glass Fiber Reinforced ABS/Epoxy Blended Polymer Composite

This research investigates the formation of polymer blends by blending Epoxy LY556 with Acrylonitrile-Butadiene-Styrene (ABS) at weight percentages ranging from 2 to 10% wt. The thermal properties, morphological characteristics, tensile strength, flexural strength, and interlaminar shear strength (ILSS) characteristics of these composites were examined. The X-ray Diffractometer (XRD) and Fourier Transform Infrared Spectrometer (FTIR) studies confirmed the presence of binary blends. The miscibility of epoxy/ABS blends is shown by the presence of a single melting peak in the Differential Scanning Calorimetry (DSC) analysis. The Thermogravimetric Analysis (TGA) findings indicate that epoxy and ABS blends exhibit greater thermal stability than pure epoxy. The tensile strength increased from 183.6 to 380.6 MPa, flexural strength increased from 165.3 MPa to 335.6 MPa, ILSS increased from 32.4 MPa to 72 MPa for 8% wt. of ABS blending, and the laminates witnessed a decrease in density and hardness values. The Scanning Electron Microscopy (SEM) images demonstrate the commendable blending characteristics and the synergistic impact of the ABS/Epoxy composite, yielding superior outcomes to the pure epoxy material.

One-step fabrication of multifunctional superhydrophobic copper surfaces via laser-assisted ablation PDMS solution

The super-hydrophobic surfaces have been greatly restricted in multi-functional applications because of the poor surface durability and multi-step processes such as preparing rough structures and low surface energy modification. In this work, a multifunctional wear-resistant super-hydrophobic surface (SHS) was primarily developed by one step laser etching polydimethylsiloxane (PDMS) i.e. the uncured PDMS layer was laser-ablated just after it was coated on the surface of copper. The wettability, morphology and chemical composition of the surfaces were characterized by a contact Angle measuring instrument, scanning electron microscope (SEM) and Fourier transform infrared spectrometer (FTIR). The results show that the developed SHS has the high contact angle (WCA) of 156.8° and low sliding angle (WSA) of 4.6°; which presents a regular linear grating array and a large number of coral-like rough structures, and the developed SHS can withstand at least 120 tape stripping tests, 40 sandpaper friction abrasion tests, 60 h of high temperature treatment (100 °C∼300 °C) or 240 h of ultraviolet light exposure tests, respectively. The self-cleaning rate and anti-fouling rate of the SHS were 94.2 % and 91.8 %, respectively, and the freezing time of droplets on the SHS is 162 s longer than that on the original copper surface, and almost 3 times longer than that on the smooth surface. In all, the non-polluting wear-resistant multifunctional SHS was primarily developed by laser ablation of metals and polymers, which has strong potential usage in the fields of anti-fouling of industrial pipeline systems and anti-icing of outdoor power transmission systems.

A methodological approach to age estimation of the intra-puparial period of the forensically relevant blow fly Calliphora vicina via Fourier transform infrared spectroscopy.

Estimating the age of immature blow flies is of great importance for forensic entomology. However, no gold-standard technique for an accurate determination of the intra-puparial age has yet been established. Fourier transform infrared (FTIR) spectroscopy is a method to (bio-)chemically characterise material based on the absorbance of electromagnetic energy by functional groups of molecules. In recent years, it also has become a powerful tool in forensic and life sciences, as it is a fast and cost-effective way to characterise all kinds of material and biological traces. This study is the first to collect developmental reference data on the changes in absorption spectra during the intra-puparial period of the forensically important blow fly Calliphora vicina Robineau-Desvoidy (Diptera: Calliphoridae). Calliphora vicina was reared at constant 20°C and 25°C and specimens were killed every other day throughout their intra-puparial development. In order to investigate which part yields the highest detectable differences in absorption spectra throughout the intra-puparial development, each specimen was divided into two different subsamples: the pupal body and the former cuticle of the third instar, that is, the puparium. Absorption spectra were collected with a FTIR spectrometer coupled to an attenuated total reflection (ATR) unit. Classification accuracies of different wavenumber regions with two machine learning models, i.e., random forests (RF) and support vector machines (SVMs), were tested. The best age predictions for both temperature settings and machine learning models were obtained by using the full spectral range from 3700 to 600 cm-1. While SVMs resulted in better accuracies for C. vicina reared at 20°C, RFs performed almost as good as SVMs for data obtained from 25°C. In terms of sample type, the pupal body gave smoother spectra and usually better classification accuracies than the puparia. This study shows that FTIR spectroscopy is a promising technique in forensic entomology to support the estimation of the minimum post-mortem interval (PMImin), by estimating the age of a given insect specimen.

Self-Assembly of Three-Dimensional Hyperbranched Magnetic Composites and Application in High-Turbidity Water Treatment.

In order to improve dispersibility, polymerization characteristics, chemical stability, and magnetic flocculation performance, magnetic Fe3O4 is often assembled with multifarious polymers to realize a functionalization process. Herein, a typical three-dimensional configuration of hyperbranched amino acid polymer (HAAP) was employed to assemble it with Fe3O4, in which we obtained three-dimensional hyperbranched magnetic amino acid composites (Fe3O4@HAAP). The characterization of the Fe3O4@HAAP composites was analyzed, for instance, their size, morphology, structure, configuration, chemical composition, charged characteristics, and magnetic properties. The magnetic flocculation of kaolin suspensions was conducted under different Fe3O4@HAAP dosages, pHs, and kaolin concentrations. The embedded assembly of HAAP with Fe3O4 was constructed by the N-O bond according to an X-ray photoelectron energy spectrum (XPS) analysis. The characteristic peaks of -OH (3420 cm-1), C=O (1728 cm-1), Fe-O (563 cm-1), and N-H (1622 cm-1) were observed in the Fourier transform infrared spectrometer (FTIR) spectra of Fe3O4@HAAP successfully. In a field emission scanning electron microscope (FE-SEM) observation, Fe3O4@HAAP exhibited a lotus-leaf-like morphological structure. A vibrating sample magnetometer (VSM) showed that Fe3O4@HAAP had a relatively low magnetization (Ms) and magnetic induction (Mr); nevertheless, the ferromagnetic Fe3O4@HAAP could also quickly respond to an external magnetic field. The isoelectric point of Fe3O4@HAAP was at 8.5. Fe3O4@HAAP could not only achieve a 98.5% removal efficiency of kaolin suspensions, but could also overcome the obstacles induced by high-concentration suspensions (4500 NTU), high pHs, and low fields. The results showed that the magnetic flocculation of kaolin with Fe3O4@HAAP was a rapid process with a 91.96% removal efficiency at 0.25 h. In an interaction energy analysis, both the UDLVO and UEDLVO showed electrostatic repulsion between the kaolin particles in the condition of a flocculation distance of <30 nm, and this changed to electrostatic attraction when the separation distance was >30 nm. As Fe3O4@ HAAP was employed, kaolin particles could cross the energy barrier more easily; thus, the fine flocs and particles were destabilized and aggregated further. Rapid magnetic separation was realized under the action of an external magnetic field.

Mg2+ ion conducting Chitosan:PVP polymer blend electrolytes for electric double layer capacitor applications

Biopolymer electrolytes are prepared using Chitosan (CS) and Polyvinyl pyrrolidone (PVP) incorporated with magnesium chloride (MgCl2). The complex formation of electrolytes are confirmed by X-ray diffraction(XRD) and Fourier Transform Infrared spectrometer(FTIR) analysis. The scanning electron microscope(SEM) reveals the surface morphology and microstructure of the electrolytes while energy dispersive spectroscopy(EDS) facilitates the presence of elements. The distribution of elements are confirmed with elemental mapping analysis. DSC analysis enlightens on thermal properties, offering an understanding of phase transitions and thermal stability of the films. CS/PVP/MgCl2(50:50:25) polymer electrolyte shows higher ionic conductivity value of 5.8 × 10−4 S/cm at 30 °C and the specific capacitance value of 86.5 Fg−1 at low scan rate of 10 mVs−1. Linear Sweep Voltammetry (LSV) analysis has been used to determine the electrochemical stability window of the electrolyte and it is found to be 0.7 V. This result indicates that the CS/PVP/MgCl2 electrolyte is a suitable material for energy storage device applications.

Room-Temperature (RT) Extended Short-Wave Infrared (e-SWIR) Avalanche Photodiode (APD) with a 2.6 µm Cutoff Wavelength.

Highly sensitive infrared photodetectors are needed in numerous sensing and imaging applications. In this paper, we report on extended short-wave infrared (e-SWIR) avalanche photodiodes (APDs) capable of operating at room temperature (RT). To extend the detection wavelength, the e-SWIR APD utilizes a higher indium (In) composition, specifically In0.3Ga0.7As0.25Sb0.75/GaSb heterostructures. The detection cut-off wavelength is successfully extended to 2.6 µm at RT, as verified by the Fourier Transform Infrared Spectrometer (FTIR) detection spectrum measurement at RT. The In0.3Ga0.7As0.25Sb0.75/GaSb heterostructures are lattice-matched to GaSb substrates, ensuring high material quality. The noise current at RT is analyzed and found to be the shot noise-limited at RT. The e-SWIR APD achieves a high multiplication gain of M~190 at a low bias of Vbias=- 2.5 V under illumination of a distributed feedback laser (DFB) with an emission wavelength of 2.3 µm. A high photoresponsivity of R>140 A/W is also achieved at the low bias of Vbias=-2.5 V. This type of highly sensitive e-SWIR APD, with a high internal gain capable of RT operation, provides enabling technology for e-SWIR sensing and imaging while significantly reducing size, weight, and power consumption (SWaP).

Synthesis of monodisperse spherical nano alumina by hydrothermal method and its mechanism study

Ultrafine alumina is widely used in advanced manufacturing industry, and its form, size and dispersion have important effects on its physicochemical properties and application characteristics. However, the superfine monodisperse spherical alumina is difficult to obtain in the actual synthesis process because the alumina precursor grain grows too fast and is easy to agglomerate. In this work, ammonium sulfate was added as the synthetic raw material to improve its dispersity. When the concentration reached 40 % of the aluminum source concentration, the isometric alumina precursor with a particle size of about 35 nm was obtained under the condition of rapid cooling. The influence of ammonium sulfate on the chemical structure of the precursor was determined by Fourier Transform Infrared spectrometer (FTIR) and X-ray photoelectron spectroscopy (XPS). The effects of reactant concentration and reaction temperature on the morphology, particle size and dispersion of the precursor as well as its mechanism were discussed in detail, and the optimal synthesis method of the nano alumina precursor was obtained. Finally, two kinds of precursors were calcined at different temperatures to obtain the equiaxed γ-Al2O3 with a particle size of 20 nm and the monodisperse spherical α-Al2O3 with a particle size of 133 nm, respectively. In this study, nano alumina precursors were synthesized by a simple and reliable method, and monodisperse ultra-fine alumina with different particle size morphologies were obtained, which has great application prospects in precision polishing, special ceramic manufacturing, and 3D printing.

Enhanced flotation separation of barite and fluorite using tetrasodium iminodisuccinate (IDS) as a biodegradable fluorite depressant: Experiments and DFT calculations

With the increasing of application fields and market demand of barite and fluorite, the research of flotation separation of barite and fluorite has attracted much attention. In this work, a novel biodegradable fluorite depressant, tetrasodium iminodisuccinate (IDS) was developed for the flotation separation of barite and fluorite in sodium dodecyl sulfonate (SDSN) system, and its interaction mechanism were revealed. The micro-flotation results proved IDS had a strong depressant on fluorite at pH 6–11. Under the best conditions (pH 8, IDS 30 mg/L, SDSN 1 × 10-4 mol/L), the BaSO4 grade and recovery in the concentrate reached 90.15 % and 92.00 %, and the CaF2 grade and recovery in the tailing reached 89.77 % and 95.32 %, which indicated that IDS could achieve the separation of barite and fluorite. Zeta potential, contact angle, Fourier Transform Infrared Spectrometer (FTIR), X-ray Photoelectron Spectroscopy (XPS) and Density Functional Theory (DFT) calculation indicated that IDS was chemisorbed on the fluorite, forming a bidentate binuclear stable adsorption configuration through the coordination of O with Ca site of fluorite, while a weak physical adsorption occurred between IDS and barite. Furthermore, the pre-adsorption of IDS hindered the binding between SDSN and fluorite, while the effect on barite was negligible. Therefore, IDS as a biodegradable and high-selectivity depressant, has potential value in the separation of barite and fluorite.

Comparison of the mechanical characteristics of biocomposites of unsaturated polyester resin with cellulose extracted from corn silk and treated corn silk

The purpose of this study is to extract cellulose from corn silk (CS) fiber and use it as a reinforcing filler in unsaturated polyester resin (UPR) matrix. In this study, the cellulose is characterized using a Fourier Transform Infrared Spectrometer (FTIR), and the resulting UPR/cellulose biocomposite's mechanical properties (such as flexural and impact testing) are assessed. Scanning electron microscopy (SEM) provided strong support for mechanical rather than a chemical bond between fiber and UPR. Additionally, the sodium hydroxide treated CS in UPR biocomposite and comparing it with neat UPR. The agricultural byproduct rich in cellulose corn silk is a natural polymer known for its structural strength and UPR has garnered attention as a biopolymer with notable flexibility, making it an appealing choice for plastic product manufacturing. However, the drawback of UPR lies in its inherent deficiency in both stiffness and strength. According to the FTIR data, extracted cellulose (CS) had fewer ketone (C = O) and hydroxyl (-OH) groups than virgin cellulose. It was shown that throughout the extraction process, hemicellulose and lignin were more eliminated, producing a more pure form of cellulose. When filled in UPR, cellulose and treated CS both caused the impact strength of UPR biocomposites to drop. For both treated CS and cellulose, it was shown that the flexural modulus and flexural strength increased as the filler amount increased to a definite percentage (12%) after which it decreased. The result revealed the tensile strength and tensile modulus achieved by 0% of fiber with 48 N/mm2 and 51 N/mm2 and highest at 12% of fiber with 54.3 N/mm2 and 68.8 N/mm2 for CS + UPR. And 53.4 N/mm2 and 69.6 N/mm2 for cellulose + UPR composite,, respectively. In comparison, the flexural characteristics of UPR/cellulose were marginally inferior to those of UPR/treated CS. However, the impact resistance showed a significant improvement, particularly with a cellulose loading of 12%. Hence, cellulose presents a greater potential for composite manufacturing due to its ability to maintain the ductile properties of UPR compared to treated CS. Moreover, processed CS and cellulose both can be used as reinforcing agents in polymers to increase their strength and stiffness.

Fabrication of Nanocellulose/Chitosan Nanocomposite Based on Loofah Sponge for Efficient Removal of Methylene Blue: Thermodynamic and Kinetic Investigations

AbstractWe established three nano-solid adsorbents: nanocellulose based on plant loofah sponge (NC), chitosan (CS), and nanocellulose/chitosan composite (CSC). These substances were employed as solid adsorbents to eliminate methylene blue (MB) dye from wastewater. Various characterization techniques were employed to investigate all the synthesized solid adsorbents, including TGA (thermogravimetric analysis), XRD (X-ray diffraction spectra), (BET) nitrogen gas adsorption-desorption, SEM (scanning electron microscope), TEM (transmission electron microscopy), FTIR (Fourier transform infrared) spectrometer, and zeta potential. According to our results, CSC showed greater thermal stability than LS and NC but lower than CS, mesoporous (2.012 nm), higher total pore volume (0.366 cm3. g− 1), specific surface area (639.3 m2. g− 1), and pHpzc of 7.22. The static adsorption of MB was well described by the Langmuir (R2 &gt; 0.9872), Temkin (R2 &gt; 0.9668), and Dubinin-Radushkevich (R2 &gt; 0.9485) models. The composite of nanocellulose and chitosan exhibited the highest Langmuir adsorption capacity (301.20 mg. g− 1) at 47 °C after a 24 h shaking period at a dosage of 2 g. L− 1 as the adsorbent and pH of 7. The adsorption of MB by the fabricated solid materials fitted well with the linear PSO (R2 &gt; 0.9806) and Elovich (R2 &gt; 0.9574) kinetic model. The enthalpy, entropy, and free energy change for the adsorption of MB onto CSC were determined to be 47.11 kJ. mol− 1, 0.172 kJ. mol− 1. K− 1, and − 3.29 kJ. mol− 1, respectively at 20 °C. Thermodynamic investigation showed that MB adsorption is spontaneous, endothermic, favorable (0 &lt; RL&lt;1, 0.017–0.313), and physisorption (EDR &lt; 8 kJ. mol− 1). Compared to the other eluents, nitric acid produced the highest desorption percentage (98.5%).