Increasing Reaction Temperature Research Articles

Synthesis, characterization, and in vivo safety evaluation of propylated Dioscorea abyssinica starch.

The use of starch, a natural polymeric material, and derivatives thereof is based on its adhesive, thickening, gelling, swelling, and film-forming properties, as well as its ready availability. The objective of this research work is to develop an effective propylated Dioscorea abyssinica starch (PDAS) as a hydrophobic excipient for pharmaceutical applications with a reasonable price. This paper reports on the synthesis, characterization, and in vivo safety evaluation of PDAS. Native Dioscorea abyssinica starch (NDAS) was modified to its propylated form with propionic anhydride and characterized. Crystallinity, morphological structure, thermal behavior, solubility, and safety of PDAS were evaluated using x-ray diffraction, SEM, thermogravimetric, gravimetric, and toxicity studies, respectively. Propionyl content and degree of substitution (DS) of starch increased significantly (p < 0.05) with an increase in reaction time and temperature. Propionyl content and DS of starch increased significantly (p < 0.05) with a decrease in the ratio of starch to pyridine and starch to propionic anhydride in the reaction medium. FTIR spectra of PDAS indicated that hydroxyl groups participated in the propylation reaction. X-ray diffraction results showed that the chemical modification destroyed the crystalline structure of the NDAS. SEM of NDAS showed a rounded shape which became irregular after propylation. Thermogravimetric curves revealed that all the PDAS samples decomposed at higher temperatures than their native counterparts. At higher DS, swelling power and solubility in an aqueous environment significantly (p < 0.05) decreased below that of the native starch. PDAS with high DS, were soluble in organic solvents at room temperature. But PDAS with lower DS didn't dissolve in all types of organic solvents used. PDAS (DS = 2.842) in distilled water did not produce adverse effects in rats. Based on the results obtained, it can be concluded that PDAS can be considered as a generally safe excipient and fulfills the physicochemical properties of a hydrophobic excipient.

Kinetic and mechanistic investigations of the oxidation of organics by near-infrared light driven thermocatalytic activation of peroxydisulfate with Fe3O4

The utilization of renewable solar energy through near-infrared (NIR)-driven photothermal catalysts offers a potential novel strategy for environmental remediation. In this work, we reported an initial demonstration of the peroxydisulfate (PDS) activation in oxidative degradation of organics (represented by bisphenol A (BPA)) via a unique NIR light-to-heat conversion effect using cost-effective and biocompatible nanoparticles (NPs). The systematical investigation of the photothermal experiments found that Fe3O4 magnetic NPs exhibit great photothermal conversion efficiency (65.4%) and have the capability to quickly elevate the system temperature to 61°C. The increased reaction temperature leads to the homolytic fission of the OO bond for producing sulfate radical (SO4−) and the derivative hydroxyl radical (OH), as confirmed by the radical quenching and electron paramagnetic resonances (EPR) tests, and in turn accelerates the thermocatalytic degradation reaction of BPA. The BPA degradation reaction rate of the NIR/Fe3O4/PDS system is about 25.8 times and 9.4 times of that in the NIR/PDS and Fe3O4/PDS systems, respectively. Both photothermal heating and surface valence states conversion of Fe2+/Fe3+ on Fe3O4 under dark conditions make a contribution to the observed oxidation reactions. Moreover, this NIR light-to-heat activation system exhibits efficient photocatalytic degradation of BPA molecules in deep water by virtue of the deep penetration capability of NIR light in water, highlighting NIR-driven photothermal catalysts hold the excellent potential to be applied in practical water restoration through PDS activation.

Hierarchical Porous Activated Carbon-Supported Ruthenium Catalysts for Catalytic Cleavage of Lignin Model Compounds

The catalytic conversion of lignin model compounds was performed using Ru/C catalysts and an autoclave reactor. The Ru/C catalysts were prepared by the impregnation method using highly porous homemade activated carbon and characterized by XRD, SEM, and specific surface area. The catalytic reactions were performed in a high pressure/temperature reactor at different temperatures and with different solvents. The results showed that the novel Ru/C catalysts prepared from carbon supports activated by the KOH agent showed higher catalytic activity than the commercial catalyst. Ethanol and 2-propanol were suitable solvents for the cleavage of the β–O–4 ether bond of 2-phenoxy-1-phenyl ethanol (~65–70% conversion) over a Ru/C-KOH-2 catalyst at 220 °C in comparison to tert-butanol and 1-propanol solvents (~43–47% conversion of 2-phenoxy-1-phenyl ethanol). Also, the increase in reaction temperature from 200 °C to 240 °C enhanced the cleavage of the ether bond with an increase in phenol selectivity from 9.4% to 19.5% and improved the catalytic conversion of 2-phenoxy-1-phenyl ethanol from 46.6% to 98.5% over the Ru/C-KOH-2 catalyst and ethanol solvent. The Ru/C-KOH-2 catalyst showed outstanding conversion (98.5%) of 2-phenoxy-1-phenylethanol at 240 °C, 1h, ethanol solvent. This novel hierarchical porous activated carbon-supported ruthenium catalyst (Ru/C-KOH-2) can be applied for the further conversion of the lignin compound.

Highly CO-selective Ni–MgO–CexZr1–xO2 catalyst for efficient low-temperature reverse water–gas shift reaction

High inertness of CO2 hinders its usage as a cost-effective C1 resource to produce value-added chemicals, and hence, reactive H2 are often employed for CO2 utilization. CO is a more reactive C1 building block that can be produced via the reverse water–gas shift (RWGS) reaction using CO2, but this requires a high temperature with robust catalysts that should endure the harsh endothermic conditions. Herein, Ni–MgO–CexZr1–xO2 (NMCxZ1–xO) catalysts with various Ce/Zr ratios, giving different strong metal–support interaction (SMSI) among metallic components, are investigated for low-temperature RWGS reaction to achieve high CO selectivity. The control of Ce/Zr ratios affords systematic changes in the oxygen storage capacity (OSC), acidity, and basicity, affording remarkable changes in the catalytic behaviors for CO2 conversion and CO selectivity. Among various NMCxZ1-xO catalysts, NMC0.6Z0.4O exhibited the highest resistance to change in reaction temperature, maintaining 100 % CO selectivity below 320 °C, whereas the CO2 conversion and CH4 selectivity of the other catalysts increased dramatically with increasing reaction temperature. The 100 % CO selectivity can be attributed to the high OSC and optimized balance of acidity and basicity of the NMC0.6Z0.4O catalyst, and its retention of catalytic activity owing to the SMSI among metallic components.

Catalytic steam reforming of methanol over highly active catalysts derived from PdZnAl-type hydrotalcite on mesoporous silica MCM-48

A kind of composite material PdZnAl(HT)/MCM-48 was synthesized by dispersing PdZnAl-type hydrotalcite (denoted as PdZnAl(HT)) on mesoporous silica MCM-48. PdZnAl(HT) was confirmed to be formed on the MCM-48 in small particles, and the small PdZnAl(HT) particles easily collapsed during increasing the temperature. A kind of novel PdZn(Al)O/MCM-48 catalyst was obtained after calcining and reducing the PdZnAl(HT)/MCM-48 precursor. PdZn alloy species were formed on the PdZnAl(HT)/MCM-48 after reducing in H2 at 673 K. PdZn(Al)O/MCM-48-2 (with a mass ratio of PdZn(Al)O to MCM-48 = 1) had a large BET surface area (431 cm2 g−1) and small size of PdZn particles (4.1 nm) at the same time. In the steam reforming of methanol, the catalytic stability of PdZn(Al)O/MCM-48-2 was much higher than that of the Cu-based catalyst CuZn(Al)O at 503 K. The methanol conversion over PdZn(Al)O/MCM-48-2 greatly increased with increasing reaction temperature and reached 99% at 513 K. PdZn(Al)O/MCM-48-2 showed higher catalytic activity than PdZnAl(HT) and PdZn/MCM-48 (imp) at the same reaction temperature. The initial CO2 selectivity and H2 selectivity over PdZn(Al)O/MCM-48-2 at 503 K were 99.6 and 99.4%, respectively. Moreover, PdZn(Al)O/MCM-48-2 showed the highest rate of H2 production among various catalysts in the steam reforming of methanol. In a long-time operation, the methanol conversion over PdZn(Al)O/MCM-48-2 decreased from 75.8 to 68.5% after 50 h on stream at 503 K. The size of PdZn particles did not increase after 50 h on stream but the carbonaceous deposits on the catalyst surface caused the deactivation. The deactivated catalyst could be regenerated by calcining in the air at 723 K followed by reducing in the H2 at 673 K. The carbonaceous deposits were eliminated by calcining in the air and the PdZn active species were formed again by reducing in H2.

Fuel properties and combustion performance of hydrochars prepared by hydrothermal carbonization of different recycling paper mill wastes

AbstractThe incineration of high‐moisture solid residues generated at the recycling paper mills represents an energetically unfavourable method of resource utilization. Alternatively, hydrothermal pre‐treatment is considered. In this study, low‐value paper sludges from three different recycling streams were hydrothermally carbonized at 205, 225, and 245°C for 3 h. The raw feedstocks and derived hydrochars were analyzed for energy properties, chemical characteristics, surface morphology, functional groups, and combustion performance employing energy densification and mass yield quantification, scanning electron microscopy, elemental analyzer, Fourier‐transform infrared spectroscopy, and thermogravimetry. The increase in reaction temperature was reported to cause a decrease in mass yield and an increase in energy densification and calorific values corresponding to 5.98%–49.35% and 10.10%–58.51% for raw fibre rejects and final sludge‐derived hydrochar, respectively. Hydrothermal carbonization (HTC) had a non‐significant influence on the energy densification of primary clarifier sludge‐derived hydrochar. Higher reaction temperatures favoured the rate of dehydration and decarboxylation, leading to hydrochars with lower H/C and O/C ratios, thereby enhancing the overall fuel properties. The low‐nitrogen and low‐sulphur fuels obtained validated the effectiveness of HTC treatment to produce high‐quality cleaner solid fuel. The burnout temperature was mostly reduced with an increase in HTC temperature. At HTC‐205 and 225°C, the ignition temperature and the combustion performance increased as a result of the HTC reaction mechanisms. HTC effectively recovered hydrochar with increased carbon content, improved energy densification, and good combustion adequacy. Hydrochar derived from recycling mills may play a role in the energy sector as a substitute for coal or in co‐combustion at coal‐fired power plants.

Oxidized oligosaccharides for chrome-free metal tanning: Utilization of food waste for the sustainability of the leather industry

Biological fermentation is widely adopted for the transformation of food waste into valuable chemicals. However, a large proportion of the organic components in food waste remain in the form of solid residues. Herein, a green methodology was explored to utilize the abundant polysaccharides in food waste fermentation residues as a masking agent for chrome-free leather tanning. First, the polysaccharides in the food waste fermentation residues were efficiently degraded into oxidized oligosaccharides in a microwave-assisted AlCl3–H2O2 system. Afterward, the resulting reaction liquid that contained water-soluble Al–oligosaccharides was used directly for leather tanning together with additional zirconium salts. An increase in reaction temperature could facilitate the conversion of the food waste fermentation residues, whereas excessively high temperatures could weaken the masking effect of oligosaccharides due to the intensively distributed molecular weight of oligosaccharides and the partial degradation of proteins. The acidity of AlCl3 was conducive to the degradation of oligosaccharides into products with low molecular weights, whereas H2O2 was responsible for introducing additional –CHO/–COOH groups to strengthen the coordination ability of oligosaccharides with metal ions. Then, the oxidized oligosaccharides could coordinate with Al/Zr species in advance to promote their penetration into collagen fibers for further cross-linking reactions. Consequently, using the oligosaccharides as a masking agent for Al-Zr tanning increased the shrinkage temperature from 70.4° to 91.6°C of the tanned leather, revealing a remarkable masking effect of the oligosaccharides from the degradation and oxidation of the food waste fermentation residues. Besides, the tear strength of the synthesized Al-Zr-oligosaccharides was as high as 77.7 N/mm, which sufficiently met the requirements of commercial use.

Dual Activation of Molecular Oxygen and Surface Lattice Oxygen in Single Atom Cu1 /TiO2 Catalyst for CO Oxidation.

The in-depth mechanism on the simultaneous activation of O2 and surface lattice O2- on one active metallic site has not been elucidated yet. Herein, we report a strategy for the construction of abundant oxygen activation sites by rational design of Cu1 /TiO2 single atom catalysts (SACs). The charge transfer between isolated Cu and TiO2 support generates abundant CuI and 2-coordinated Olat sites in Cu1 -O-Ti hybridization structure, which facilitates the chemisorption and activation of O2 molecules. Simultaneously, the Cu1 -O-Ti induced TiO2 lattice distortion activate the adjacent surface lattice O2- , achieving the dual activation of O2 and surface lattice O2- . The Cu1 -O-Ti active site switches the CO oxidation mechanism from Eley-Rideal (80 °C) to Mars-van Krevelen route (200 °C) with the increase of reaction temperature. The dual activation of O2 and surface lattice O2- can by modulating the electron properties of SACs can boost the heterogeneous catalytic oxidation activity.

Dual Activation of Molecular Oxygen and Surface Lattice Oxygen in Single Atom Cu1/TiO2 Catalyst for CO Oxidation

AbstractThe in‐depth mechanism on the simultaneous activation of O2 and surface lattice O2− on one active metallic site has not been elucidated yet. Herein, we report a strategy for the construction of abundant oxygen activation sites by rational design of Cu1/TiO2 single atom catalysts (SACs). The charge transfer between isolated Cu and TiO2 support generates abundant CuI and 2‐coordinated Olat sites in Cu1−O−Ti hybridization structure, which facilitates the chemisorption and activation of O2 molecules. Simultaneously, the Cu1−O−Ti induced TiO2 lattice distortion activate the adjacent surface lattice O2−, achieving the dual activation of O2 and surface lattice O2−. The Cu1−O−Ti active site switches the CO oxidation mechanism from Eley‐Rideal (80 °C) to Mars–van Krevelen route (200 °C) with the increase of reaction temperature. The dual activation of O2 and surface lattice O2− can by modulating the electron properties of SACs can boost the heterogeneous catalytic oxidation activity.

Conversion of empty fruit bunches (EFBs) by hydrothermal carbonization towards hydrochar production

Empty fruit bunches (EFBs) are waste from the palm oil production. It has a high potential for use as a renewable carbon resource. As it typically contains a high moisture content, it requires a moisture removal step prior to transformation into high-value products via thermochemical processes. Hydrothermal carbonization (HTC) is an effective method for converting moisture-rich biomass into carbon-based products. The feasibility of employing EFBs as a feedstock for the production of promising carbonaceous materials via HTC in a batched stirred tank reactor was investigated in this research. The parameters influencing the HTC’s product properties, including reaction temperatures ranging from 160 to 280 °C and reaction times ranging from 2 to 8 h, were examined. The mass ratio of dried EFBs to water content was kept constant at 1:10. The hydrochar properties were evaluated using ultimate analysis, proximate analysis, N2-physisorption, Scanning Electron Microscope (SEM), and Fourier Transform Infrared Spectroscopy analysis (FTIR). The carbon content and amount of fixed carbon increased with increasing reaction temperature. The well-developed hydrochar was produced at a temperature of 240 °C for 2 h, providing a carbon content of 70% and a fixed carbon of 35%, with a solid yield of 41%. The surface area of this hydrochar was 11.21 m2/g, the pore volume of 0.033 cm 3/g, and the pore diameter of 10.89 nm. This study showed the effective preparation of materials with high carbon content from moisture-rich agricultural wastes.

Reaction laws of polycyclic aromatic hydrocarbons and heteroatomic compounds in hydrocracking process

Based on the Structure Oriented Lumping (SOL) method, a molecular-level reaction kinetic model for hydrocracking process was established to investigate the reaction laws of polycyclic aromatic hydrocarbons (PAHs) and heteroatomic compounds in hydrocracking process and calculate the molecular compositions of hydrocracking products. Molecules showed different reaction laws due to the differences of the initial contents, the structural increments and their positions in the reaction network. Since the hydrodenitrogenation reactions of indole and carbazole homologs were more difficult to carry out than the hydrodesulfurization reactions of benzothiophene and dibenzothiophene homologues, the denitrification rate was lower than the desulphurization rate at the outlet of the hydrotreating section. When the reaction temperature of the hydrotreating section was 360 °C, the conversion rates of sulfides and nitrides were 98.4 % and 91.3 %, respectively. The increase of reaction temperature intensified the hydrogenation saturation of aromatics, the ring opening of naphthenes and the cracking of paraffins. As the reaction temperature of the hydrocracking section rose from 370 °C to 410 °C, more isomerized carbon ions were generated due to the β-position cracking of paraffins. The mass ratio of methylbutane to n-pentane in light naphtha increased from 1.29 to 3.08. The increase of reaction temperature accelerated the side chain cracking reactions of naphthenes with 4 or more carbon atoms in the side chains, and generates more naphthenes with 0 to 3 carbon atoms in the side chains. Aromatics mainly underwent the ring-by-ring hydrogenation saturation reactions in the hydrotreating section, and bicyclic aromatic hydrocarbons was significantly easier to be hydrogenated than monocyclic aromatic hydrocarbons.

Energy Consumption Analysis of a Diesel Hydrotreating Unit Using an Aspen Simulation

The petrochemical industry is traditionally a high energy consumption industry, thus energy saving in this industry is of great significance in terms of trying to achieve the national goal of “carbon-peak and carbon neutrality” in China. Diesel is one of the main products of petrochemical enterprises. The energy consumption of a diesel hydrotreating (HDT) unit is relatively high due to the high reaction temperature and pressure of HDT reactors. In order to further explore the energy consumption of diesel HDT units under different operating conditions, this paper establishes a full-process simulation based on the kinetics of hydrodesulfurization, hydrodenitrogenation, and aromatics saturation, in Aspen Plus to discuss the effect of different operating conditions on the electricity, steam, and fuel gas consumptions. The results show that with the increase of reaction temperature or reaction pressure, the sulfur content in diesel oil decreases, but the consumption of related utilities and comprehensive energy consumption increases. In addition, this paper also analyzes the energy consumption changes under the operating condition boundaries when the diesel quality is unchanged. When the reaction pressure is 8 MPa and the reaction temperature is 317.5 °C, the comprehensive energy consumption is 5% lower than the energy consumption with the reaction pressure of 6 MPa and the temperature of 320 °C. Therefore, on the premise of satisfying the diesel product quality, the comprehensive energy consumption of the diesel HDT unit can be reduced by increasing the reaction pressure and decreasing the reaction temperature.

Effects of Preparation and Self-Assembly of Poly(Styrene-Acrylic Acid) (P(St-AA)) Microspheres upon Constructed Photonic Crystals with Structural Color on Wood Surfaces

Colloidal microspheres could be used as raw materials to construct the photonic crystal modification layers on wood surfaces, and the wood would produce gorgeous structural color effect. The diameter, monodispersity and self-assembly of colloidal microspheres directly affect the well-structure order of photonic crystals. Therefore, poly(styrene-acrylic acid) (P(St-AA)) shell-core microspheres were prepared by emulsion polymerization. The effects of the reaction time, amount of initiator and emulsifier and reaction temperature on the particle size and dispersity of colloidal microspheres during polymerization were analyzed by single-factor experiments. The P(St-AA) colloidal microspheres self-assembled on wood surfaces and formed photonic crystals with structural color through thermally-assisted gravity deposition. The effects of the amount of emulsion coating per unit surface area and ambient temperature on the optical properties of the photonic crystals were investigated. It was found that the particle size of the synthesized microspheres increased with the increase of initiator amount and reaction temperature and the decrease of emulsifier; however, the effect of reaction time on microspheres was less regular. The best optical properties of the photonic crystals on wood surfaces were obtained using 0.408 μL/mm2 emulsion coating at a temperature of 50 °C. The photonic crystals were composed of both ordered and disordered layers.

SnO2 Nanoparticles: Green Synthesis, Characterization, and Water Treatment

The green synthesis approach was utilized to synthesize tin dioxide (SnO2) nanoparticles (NPs) using Ocimum Basilicum leaves extract with different concentrations (10, 15, 20 ml) and different reaction temperatures (30, 60, 90 °C). The green synthesis method is considered economical, environmentally friendly, and non-toxic. X-ray diffraction patterns of the synthesized SnO2 NPs have displayed a tetragonal crystalline structure. The crystallite size of SnO2 NPs increased from 15.12 to 17.9 nm with increasing reaction temperature while decreasing from 20.68 to 17.9 nm with increasing extract concentrations. The morphology of the synthesized SnO2 NPs was investigated using high-energy transmission electron microscopy (HR-TEM). The optical energy gap was determined using the diffuse reflectance UV–vis spectra range (300–1200) nm of SnO2 NPs at different reaction temperatures and different extract concentrations. UV/Visible Spectrophotometer was used for studying the photodegradation of methylene blue dye (MB) dye. The photocatalytic degradation of MB revealed that SnO2 NPs at reaction temperature 90 °C degraded 69% of MB solution when exposed to UV illumination for 90 min while the degradation reaches 90% for 180 min of exposure. It was obvious that the degradation rate of MB was increased with the increase of reaction temperature, and the extract concentration.

Enhanced Performance and Stability of a Trimetallic CuZnY/SiBEA Catalyst in Ethanol to Butadiene Reaction by Introducing Copper to Optimize Acid/Base Ratio

Bioethanol to butadiene is currently the most promising non-oil-based butadiene production route. Here, copper is introduced into the conventional bimetallic zeolite catalyst to partially substitute for zinc; the isolated tetracoordinated Cu(II) species are formed, with weak and strong basic sites transformed into medium acid sites in trimetallic CuZnY/SiBEA catalyst. A partial substitution of zinc by copper increases the dispersion of metal, reduces the formation of ZnO clusters, decreases the pore blockage, and enhances the total pore volume of catalyst. The Cu1Zn2Y5/SiBEA catalyst with an appropriate 0.33 Cu/(Cu + Zn) mass ratio, a highest medium acid sites/(weak + strong) basic sites value of 6.17, and largest total pore volume of 0.251 cm3/g in all samples presents excellent catalytic performance in the ethanol to butadiene reaction: 99.01% ethanol conversion and 73.36% butadiene selectivity, higher than most reported ethanol to butadiene catalysts. The isolated tetracoordinated Cu(II) structure is stable, which is beneficial to the stability of trimetallic catalyst; when the reaction time is 60 h, the butadiene selectivity is 45.95%, 14% higher than corresponding bimetallic catalyst. The butadiene productivity of Cu1Zn2Y5/SiBEA catalyst reaches up to 1.68 gBD·gcat−1·h−1 at WHSV = 6 h−1 and time-on-stream = 8 h. Increasing reaction temperature could linearly increase the ethanol conversion, while the butadiene selectivity increases first and then decreases, the suitable temperature is 375 ℃ for the highest butadiene yield.

Transformation and distribution of nitrogen and phosphorus in sewage sludge during supercritical water gasification

In this study, the comprehensive investigation of the transformation and distribution of nitrogen (N) and phosphorus (P) during supercritical water gasification (SCWG) of sewage sludge were carried out. The nitrogen in raw sludge is mainly in form of organic nitrogen, metal nitrides and silicon oxynitride (NSi2O). During SCWG, most of organic nitrogen was converted to ammonium nitrogen. With the increase of reaction temperature and time, nitrogen gradually migrated from solid phase to liquid phase. Phosphorus in raw sludge mainly existed in the form of calcium phosphide (Ca3P2), triphenylethylene phosphine (Ph3P) and cyclopentyl phosphide (Ph2PSH). During SCWG, Ca3P2, Ph3P and Ph2PSH were decomposed and degraded into phosphates, enriched in the solid phase. Phosphides in the liquid phase are rarely detected, as more phosphorus was deposited into the solid product with increasing reaction temperatures and time. Therefore, the liquid product can be potentially used as nitrogen containing fertilizer, and P can be recovered from solid product after SCWG.

Solvent Effect on the Synthesis of Oleylamine Modified Au Nanoparticles and Their Self-Assembled Film for SERS Substrate

The preparation and self-assembling of monodisperse gold nanoparticles (Au NPs) is of great significance for its SERS application. According to the oleylamine-reduced method, oleylamine (OAm) serves as the reducing agent and stabilizing agent, and the effects of different reaction parameters such as solvent and temperature on the size and dispersity of Au NPs have been evaluated. The Au NPs synthesized with toluene as the solvent have the best dispersity and narrowest particle size distribution with adjustable sizes. The particle size gradually increases with the increase in reaction temperature. The highly ordered self-assembly film of Au NPs was employed as surface-enhanced Raman scattering (SERS) substrate for the probing molecule of rhodamine 6G. The Au substrate exhibits excellent spatial uniformity and SERS reproducibility, which indicates its practicability as a substrate. This study provides a simple synthesis strategy of highly ordered monodispersed Au NPs, which can serve as a SERS substrate with excellent spatial uniformity and SERS re-producibility.

The efficient degradation of diclofenac by ferrate and peroxymonosulfate: performances, mechanisms, and toxicity assessment.

In this study, the degradation efficiency and reaction mechanisms of diclofenac (DCF), a nonsteroidal anti-inflammatory drug, by the combination of ferrate (Fe(VI) and peroxymonosulfate (PMS) (Fe(VI)/PMS) were systematically investigated. The higher degradation efficiency of DCF in Fe(VI)/PMS system can be obtained than that in alone persulfate (PS), Fe(VI), PMS, or the Fe(VI)/PS process at pH 6.0. DCF was efficiently removed in Fe(VI)/PMS process within a wide range of pH values from 4.0 to 8.0, with higher degradation efficiency in acidic conditions. The increasing reaction temperature (10 to 30 ℃), Fe(VI) dose (6.25 to 100µM), or PMS concentration (50 to 1000µM) significantly enhanced the DCF degradation. The existences of HCO3¯, Cl¯, and humic acid (HA) obviously inhibited the DCF removal. Electron paramagnetic resonance (EPR), free radical quenching, and probing experiments confirmed the existence of sulfate radicals (SO4•¯), hydroxyl radicals (•OH), and Fe(V)/ Fe(IV), which are responsible for DCF degradation in Fe(VI)/PMS system. The variations of TOC removal ratio reveal that the adsorption of organics with ferric particles, formed in the reduction of Fe(VI), also were functioned in the removal process. Sixteen DCF transformation byproducts were identified by UPLC-QTOF/MS, and the toxicity variation was evaluated. Consequently, eight reaction pathways for DCF degradation were proposed. This study provides theoretical basis for the utilization of Fe(VI)/PMS process.

Synthesis of Fe3O4 at different reaction temperatures and investigation of its magnetic properties on giant magnetoresistance (GMR) sensors for bio-detection applications

Magnetite (Fe3O4) nanoparticles with different reaction temperatures (TR= 40, 60 and 80°C) for the application of bio-detection have been successfully synthesized using the co-precipitation method. The average crystallite sizes of samples increased with the increase of TR and all samples showed high crystallinity with an inverse spinel cubic structure. The grain size increased with the increase of TR. On the other hand, all samples have polycrystalline structure and the brightest intensity at Miller's index (311). From the results of the vibrating sample magnetometer (VSM) analysis, it was found that there was an increase in magnetic properties such as Hc, Mr and Ms along with the increase reaction temperature. For example, the saturation magnetization increased with the increase of TR. Next, the giant magnetoresistance (GMR) biosensor was explored by using an exchange-biased GMR sensor with the Wheatstone bridge method to detect Fe3O4 with variations of reaction temperature in an alcohol solution of 50 μg/ml. A DC in-plane magnetic field was used for this measurement. It was found that the Vout curve is sensitive to the presence of Fe3O4 and the maximum Vout appears at 2.8 Oe by applying an external field to the sensor of ± 95 Oe. The Vout difference increased with the increase of reaction temperature, which can be attributed to higher saturation magnetization, causing more difficult fringing of the magnetic field. The relationship between TR and |ΔV| is ΔV = 0.0175x + 0.49, in which |ΔV| linearly increases with the increase of reaction temperature. This study demonstrates the feasibility of Fe3O4-based detection using a GMR sensor and Fe3O4 as magnetic labels will be useful for potential bio-detection applications.

Effect of reaction temperature and raw material particle size on the composition of corn straw pyrolysis biological oil

Quartz sand was used as bed material in a small fluidized bed reactor with 1 kg/h feed. Corn straw powder with particle size of 20–40 mesh, 40–60 mesh, 60–80 mesh and 80–120 mesh was used as raw material for rapid pyrolysis at reaction temperatures of 400 °C, 450 °C, 500 °C and 550 °C. The bio-oil obtained after liquefaction of pyrolysis gas was analyzed. The variation trend of bio-oil composition in pyrolysis of corn straw powder with different reaction temperatures and raw material sizes was compared. The results show that: (1) the content of 3-hydroxyl-2-phenyl-2-acrylic acid in bio-oil increases with the decrease of raw material particle size, but it is less at 450 °C; (2) with the increase of reaction temperature, the content of hydroxyacetaldehyde in bio-oil increases at first and then decreases: the content of hydroxyacetaldehyde in bio-oil is the highest at 500 °C when the particle size is 20–40 mesh, and the highest at 450 °C with the other three particle sizes. Compared with other particle sizes, raw material with the particle size of 60–80 mesh is not conducive to the formation of aldehyde compounds; (3) the reaction temperature of 500 °C and the particle size of 60–80 mesh of raw materials are more conducive to the formation of phenolic compounds in bio-oil; (4) the ester compounds with particle size of 20–40 mesh in bio-oil is 20% higher than that of other particle sizes; (5) the reaction temperature and the particle size of raw materials had no significant effect on the formation of ketones, alcohols and alkane compounds in bio-oils.