Effect Of Hydrothermal Treatment Research Articles

Partial oxidation of TiN coating by hydrothermal treatment and ozone treatment to improve its osteoconductivity

Dental implants made of pure titanium suffer from abrasion and scratch during routine oral hygiene procedures. This results in an irreversible surface damage, facilitates bacteria adhesion and increases risk of peri-implantitis. To overcome these problems, titanium nitride (TiN) coating was introduced to increase surface hardness of pure titanium. However, the osteoconductivity of TiN is considered to be similar or superior to that of titanium and its alloys and therefore surface modification is necessary. In this study, TiN coating prepared through gas nitriding was partially oxidized by hydrothermal (HT) treatment and ozone (O3) treatment in pure water to improve its osteoconductivity. The effects of HT treatment and O3 treatment on surface properties of TiN were investigated and the osteoconductivity after undergoing treatment was assessed in vitro using osteoblast evaluation. The results showed that the critical temperature for HT treatment was 100°C since higher temperatures would impair the hardness of TiN coating. By contrast, O3 treatment was more effective in oxidizing TiN surfaces, improving its wettability while preserving its morphology and hardness. Osteoblast attachment, proliferation, alkaline phosphatase (ALP) expression and mineralization were improved on oxidized specimens, especially on O3 treated specimens, compared with untreated ones. These effects seemed to be consequences of partial oxidation, as well as improved hydrophilicity and surface decontamination. Finally, it was concluded that, partially oxidized TiN is a promising coating to be used for dental implant.

Characterization of NO emission in combustion of hydrothermally treated antibiotic mycelial residue

The NO emission characteristics from both conventional and air-staged combustions of antibiotic mycelial residue were investigated in the temperature range of 1073–1273K. The effect of hydrothermal treatment (HTT) prior to combustion on the NO emission was clarified. In conventional combustion, the NO emission from combustion of the hydrothermally pretreated antibiotic mycelial residue (HTT-AMR) was 20–30% lower than that from combustion of the directly dried antibiotic mycelial residue (Dried-AMR). By air-staged combustion, the NO emission of HTT-AMR was reduced by about 45% at 1273K, compared to that by conventional combustion. As a result, the NO emission was largely reduced by 57% by air-staged combustion of HTT-AMR at 1273K in comparison with conventional combustion of Dried-AMR, showing a significant combining effect of HTT and air-staged combustion on the NO emission. Results of thermogravimetric analysis and X-ray photoelectron spectroscopy revealed that the AMR based fuels have only volatile matters which consist of light and heavy volatiles. Deconvoluting the NO emission curves demonstrated that the reduction in NO emission via HTT mainly resulted from the removal of the nitrogen in the light volatile as the form(s) of amino acid or/and ammonia, while the reduction via air-staged combustion was because air-staged combustion suppressed the formation of NO from the heavy volatile.

The effect of hydrothermal treatment on attrition during the fluidized bed combustion of paper sludge

A combination of experimental techniques was employed to test primary fragmentation and char particle attrition by abrasion during fluidized bed (FB) combustion of raw paper sludge (Raw-PS), hydrothermally treated paper sludge (HTT-PS), and a subbituminous coal (Sub-C), for comparison. The hydrothermal treatment (HTT) was conducted by a pilot-scale reactor at 197°C (1.9MPa) for 30min. The results showed that all three samples extensively underwent primary fragmentation. Char attrition tests under inert conditions showed that Sub-C intensely experienced particle rounding off at the beginning, but after that it became very strong against mechanical abrasive attrition, followed by HTT-PS and Raw-PS, respectively. The oxidative char attrition tests showed that Sub-C exhibited an initial low amount of carbon elutriation rate followed by an attrition enhancement effect at later stages of burn-off, whereas for the Raw-PS and HTT-PS attrition was always lower than under inert conditions due to extensive postcombustion of fines. HTT-PS always produced a lower amount of elutriated carbon than Raw-PS and this indicates better combustion performance as well as lower unburned carbon emission. Finally, the Primary Ash Particle Size Distribution (PAPSD) of the three fuels was determined, showing that the paper sludge would contribute much more than coal to the ash bed inventory in a full-scale FB combustor.

The Effect of Hydrothermal Treatment on the Color Stability and Chemical Properties of Birch Veneer Surfaces

The effects of hydrothermal pre-treatment on the color of silver birch veneer were determined. Spectrophotometric and chemical analyses of the veneer by means of extraction were conducted to determine the detailed chemical characteristics of the veneers. Results from spectrophotometric analysis revealed a significant increase in lightness (L*) and a decrease in yellowness (b*) in the veneer produced from a log soaked at 70 °C in short-term. Conversely, the effect of long-term storage resulted in a significant reduction in L* and an increase in b*. Chemical analyses of the veneer extract identified a moderate negative correlation between soluble proanthocyanidins content and treatment temperature. A higher amount of wood extractives, such as lipophilic extractives, free monosaccharides, and other organic substances, were obtained from wood material soaked at 70 °C than at 20 °C, which was most likely due to moderate chemical changes during treatment. Comparison of the results between dried veneers and wet veneers from the water extraction study revealed that the dried veneers had higher amounts of lipophilic matter and less water-soluble organic matter than the wet veneers. Other aspects of the loss of soluble proanthocyanidins in the birch veneer during plywood manufacturing are discussed.

Effect of hydrothermal treatment on catalytic activity of amorphous mesoporous Cr2O3–ZrO2 nanomaterials for ethanol oxidation

Mesoporous 0.25Cr2O3–0.75ZrO2 binary oxide catalysts (CZ-H) with high specific surface areas were successfully synthesized by hydrothermal treatment. The effect of synthesis conditions, such as hydrothermal temperature and time of CZ-H nanomaterials were investigated by X-ray diffraction (XRD), high-resolution transmission electron microscopy (HR-TEM), energy dispersive spectroscopic (EDS), UV–vis diffuse reflectance spectroscopy (DRS) and N2 adsorption–desorption measurements (BET). The XRD analysis indicated the formation of amorphous materials of binary oxides. The results showed that hydrothermal temperature and time of CZ-H nanomaterials had great influence on the average particle diameter and surface area. Under the optimum synthesis conditions, the best CZ-H nanomaterial synthesized at 210 °C for 3 h (i.e., CZ-H213), presented spherical structure with smallest average particle diameter found to be 1.5 nm and possessed highest surface area of 526.6 m2/g. Optical studies by UV–vis spectroscopy for the different CZ-H nanomaterials exhibit slightly blue shift from 3.20 to 3.33 eV due to quantum confined exciton absorption. Moreover, hydrothermal synthesis leads to catalysts with higher surface area and with better acid–base properties than conventional co-precipitation method. Compared to the other nanomaterials, the CZ-H213 catalyst appears to be the best candidate for further application in acid–base catalysis and reusability.

Cr/SiO2 mesoporous catalysts: Effect of hydrothermal treatment and calcination temperature on the structure and catalytic activity in the gas phase dehydration and dehydrogenation of cyclohexanol

Cr/SiO2 mesoporous materials (Cr-MCM-41) were obtained by hydrothermal synthesis. The effect of hydrothermal treatment and calcination temperature on the structure and catalytic behavior of synthesized materials were analyzed. The materials were characterized by XRD, N2 adsorption–desorption, TEM-SEM, TG-DTA, FTIR-HATR, DRUV–vis and XPS. The hydrothermal treatment promoted the incorporation of Cr3+ into the silica network, improving their resistance to oxidation. The calcination in air produces the simultaneous presence of Cr3+ and Cr6+ ions, and their relative amounts depend both on the hydrothermal pretreatment and the calcination temperatures. The Cr3+ ions constituted coordinative unsaturated acid centers responsible of the cyclohexanol to cyclohexene dehydration reaction. Moreover, the Cr6+ ions correspond to either isolated monochromate species linked to the silica structure or to polychromate aggregates, which produce crystalline α-Cr2O3 clusters after calcination in air to 450°C. The monochromate centers were active for the dehydrogenation reaction. So, although dehydration was the main reaction, the dehydrogenation reaction to cyclohexanone also was observed after calcination in air to 450°C.

Influence of steam-calcination and acid leaching treatment on the VGO hydrocracking performance of faujasite zeolite

The effect of hydrothermal treatment and mild acid leaching on the physico-chemical properties of zeolite Y and its vacuum gas oil hydrocracking performance was investigated. Ultra-stabilized Y (USY) zeolites were obtained by steam-calcination at 500, 600 and 700°C. Steam-treated zeolites were further subjected to a mild acid leaching treatment. The zeolite samples were characterized by XRD, elemental analysis, XPS, N2 adsorption, 29Si and 27Al NMR and FTIR spectroscopy of adsorbed pyridine. Steam-calcination resulted in dealumination and with increasing severity the micropore surface area and the framework Al content decreased. At the same time, the Al content at the zeolite crystal surface increased. Acid leaching improved the pore accessibility and acid properties due to the extraction of extraframework Al species (EFAl). NiMoP-based hydrocracking catalysts were prepared from the modified USY zeolites with alumina as binder. Hydrocracking activities correlated with the acidity of the zeolites. Too severe steam treatment led to depopulation of acid sites and lowered the hydrocracking performance. Hydrocracking catalysts based on the acid leached zeolites were more active than the ones based on the corresponding steam-treated zeolites. It is based on the removal of agglomerated extraframework Al species that block the access to some of the micro- and mesopores. This study points out that, aside from the acidity, also other parameters such as pore accessibility and the presence of EFAl have considerable influence on the hydrocracking of the heavy molecules in a gas oil feed.

Effect of Hydrothermal Treatment on Macro/Micro Nutrients Extraction from Chicken Manure for Liquid Organic Fertilizer Production

In order to study the influence of the hydrothermal treatment technology (HTT) on macro/micro nutrients extraction from two types of chicken manure (broiler chicken manure (BCM) and laying hen chicken manure (LCM)), hydrothermal treatment followed by the solid/liquid separation of the HTT product was performed with a fixed feedstock to water mass ratio (1:3), 30 min reaction time and three different reaction temperatures (160oC, 180oC, 200oC). More than 50% of N can be extracted from solid to liquid after HTT for both BCM and LCM. Moreover, the organic N content was more than 80% in all liquid samples and it was increasing with the increase of HTT temperature. According to all the results, 180oC is the optimum temperature for both types of chicken manure and the pH value of the liquid extracted at the optimum temperature was close to 7 for both types of chicken manure. The heavy metal contents in the liquid obtained from BCM and LCM were not detected. It was observed that macro nutrients and micro-nutrients were dissolved in the liquid after HTT. Original Research Article Perera et al.; BJECC, 5(1): 64-75, 2015; Article no.BJECC.2015.005 65

Effect of Hydrothermal Treatment on the Nutritional and Functional Properties of Husked and Dehusked Buckwheat

Buckwheat (Fagopyrum esculentum) is a rich source of many bioactive components, which have been shown to provide various health benefits. In the present investigation, effect of hydrothermal treatment on the buckwheat seeds and changes in physico-chemical and functional properties (of husked and dehusked flours) were studied. Results revealed that, the protein content decreased as the duration of parboiling increased whereas crude lipid, fiber and ash content increased in both the husked and dehusked flours. It was also observed that the mineral content was higher for the husked as compared to dehusked flours. Hydrothermal processing increased swelling power and solubility. The product developed from the dehusked flour was preferred over the husked flour product.

The Effect of Hydrothermal Treatment on the Aromatization Performance of HZSM-5 Modified by Zn, P

Zn and P modified HZSM-5 zeolite catalysts were prepared by impregnation method using HZSM-5 zeolite prior to hydrothermal treatment. The surface area, the acid center style, and the acid strong distributing on hydrothermal treatment HZSM-5 zeolite were characterized by XRD, BET, NH3-TPD, and FT-IR techniques. Meanwhile, the influence of hydrothermal treatment temperature on the aromatization performance of the catalyst was investigated using FCC gasoline (50–100°C fraction) as feedstock. The result showed that, along with the temperature of hydrothermal treatment heightening, the surface area reduced and pore volume increased a little, however, the pore size clearly increased; at the same time the total acid amount and the number of strong acid sites of HZSM-5 were reduced significantly. With the hydrothermal treatment temperature increasing, the catalyst initial activity gradually decreased and the stability presented the trend of first increase then decrease. The HZSM-5, which was treated by hydrothermal at 550°C modified by zinc and phosphor, exhibited preferable aromatization performance. After reacting 16 h, the conversion of olefins, the contents of aromatic, and the yield of liquid products were 90.26, 54.06, and 10.02%, respectively.

Effect of Hydrothermal Treatment on Precipitated Iron Catalyst for Fischer–Tropsch Synthesis

Two series of Fe/Cu/K catalysts were prepared by co-precipitation (CP-xK) and by co-precipitation accompanied with hydrothermal treatment (HY-xK), respectively. The catalysts were investigated by N2 adsorption, X-ray diffraction (XRD), Mossbauer effect spectroscopy (MES), scanning electron microscopy (SEM), high-resolution transmission electron microscopy (HRTEM), H2 temperature-programmed reduction (H2-TPR) and thermogravimetric analysis. N2 adsorption revealed that HY-xK catalysts displayed relatively low surface area, but generated additional macropore. XRD and SEM showed that HY-xK catalysts were well grown crystallite, while the CP-xK catalysts were amorphous. In addition, hydrothermal treatment remarkably influenced the growth orientation of hematite nanocrystals, resulting in the preferential exposure of the (110) plane. HRTEM also indicated that HY-1.32K was dominated by Fe2O3 nanocrystals with (110) plane, and the CP-1.38K primary particle mainly exposed (104) plane. The H2-TPR profiles for the two series of catalysts were similar, though the merged and smooth peak of HY-xK catalysts possibly suggested that the component elements were more uniform. MES and XRD indicated that the catalyst after hydrothermal treatment can be easily reduced into active carbide phases in Fischer–Tropsch synthesis (FTS) reaction. In FTS reaction, the HY-xK catalysts showed higher activity and better stability than the CP-xK catalysts given comparable K content.

Effect of hydrothermal treatment on the structure and acid properties of the surface of molded gamma-aluminum oxide

Mechanism of the hydrothermal modification of gamma-aluminum oxide was studied. A set of physicochemical methods demonstrated that boehmite crystals are formed in macropores (>500 nm) by the dissolution/precipitation mechanism, whereas in mesopores (<20 nm), rehydration of primary blocks of aluminum oxide occurs from the surface into the bulk. As a result of the phase transition, aggregates of primary oxide blocks are dispersed, which leads, at a certain treatment duration, to an increase in the specific surface area. In this case, the content of acid centers also increases according to the results of a temperature-programmed desorption of ammonia, as also does the catalytic activity in the reaction of skeletal isomerization of n-butenes.

Structural and optical insights to enhance solar cell performance of CdS nanostructures

Sol–gel spin coating technique is used to prepare nanostructured CdS deposited on glass and quartz substrates with Cd:S 1.2:0.1mol/L, 1000rpm spin coating speed at 400°C and 800°C annealing temperatures, respectively. The effect of hydrothermal treatment on physical properties of crystalline size and morphology is reported. Structural, topographical and optical properties are investigated using X-ray diffraction (XRD), atomic force microscopy (AFM), UV–visible spectrophotometer (UV) and photoluminescence (PL). The optical properties are investigated experimentally and theoretically to verify the suitable model for electro-optical systems. Our results are in agreement with experimental and theoretical data.

Effects of hydrothermal treatment on the catalytic activity of cobalt-doped catalysts for oxygen reduction reaction

A series of cobalt-doped catalysts (Co–PPy/BP) is synthesized by hydrothermal treatment of polypyrrole-modified BP2000 in cobalt nitride solution. The hydrothermal temperature is varied from 80 °C to 180 °C to investigate the effect of treatment temperature on the catalytic site formation for oxygen reduction reaction (ORR). Treatment temperature is found to slightly affect the structure and morphology of the synthesized catalysts. However, the catalytic activity of the synthesized Co–PPy/BP increases with increased treatment temperature up to 160 °C because higher treatment temperatures promote pyrrolic-N conversion to Co–Nx. Co–Nx catalyzes H2O2 electroreduction reaction, which increases the number of electrons transferred during ORR. However, the hydrothermal treatment at 180 °C leads to decreased pyrrolic-N and Co–Nx contents, which results in decreased catalytic activity of the synthesized Co–PPy/BP.

Natural potato or carbon nanorods, spheres, spiral and nanoparticle structures

The effect of hydrothermal treatments on the properties of the natural potato was investigated. The natural potato was chosen here because it is not only used for food, but also for other, nonfood purposes. The obtained carbon nano and microstructures with different morphologies and size were characterized by FT-IR, XRD, EDX, SEM and TEM. The effects of reaction parameters, such as temperature and reaction time on the morphology and particle size of products were investigated. To the best of our knowledge, there is no report on the fabrication of carbon nanostructures with natural potato.

Effect of hydrothermal treatment on the flexural strength of ceramic-veneered zirconia

Effect of hydrothermal treatment on the flexural strength of ceramic-veneered zirconia

The Effect of Hydrothermal Treatment on Silver Nanoparticles Stabilized by Chitosan and Its Possible Application to Produce Mesoporous Silver Powder

Aggregation state of silver nanoparticles dispersed in an aqueous solution greatly varies with storage and treatment conditions. In this study, silver nanoparticles synthesized in chitosan solution by a chemical reduction method were hydrothermally treated at different temperatures. The variation in the aggregation state of silver nanoparticles in the solution was observed by UV-Vis spectroscopy and field emission transmission electron microscopy. Results indicated that a phase transition occurred while silver nanoparticles were hydrothermally treated for 5 h at 100 and 120∘C; however, they aggregated and completely precipitated at 150∘C. Mesoporous silver powder obtained by hydrothermal treatment at 150∘C was characterized by using X-ray diffraction technique, BET analyzer, and scanning electron spectroscope.

Effect of γ-Al2O3 hydrothermal treatment on the formation and properties of platinum sites in Pt/γ-Al2O3 catalysts

The effect of hydrothermal treatment (HTT) of γ-alumina on the state of its surface functional cover, anchoring of hexachloroplatinate, and properties of platinum sites was investigated. Hydrothermal treatment of γ-Al2O3 was found to increase the fraction of surface bridging OH groups and concentration of Lewis acid sites (LAS) and alter the metal complex–support interaction. Adsorption of hexachloroplatinate on the support surface is accompanied mainly by the formation of outer-sphere complexes, which are characterized by a lower reduction temperature. As a result, dispersion and electronic state of supported platinum are changed. Influence of γ-Al2O3 hydrothermal treatment on the catalytic properties of Pt/Al2O3 in n-hexane transformations and propane dehydrogenation was demonstrated. The revealed effect of γ-Al2O3 hydrothermal treatment on the formation of platinum sites in Pt/Al2O3 catalysts can be of fundamental importance for the steps of supported system synthesis where solid phase is contacting with water and aqueous solutions (impregnation and drying).

Single-pot synthesis of ordered mesoporous silica films with unique controllable morphology

Mesoporous silica films consisting of a monolayer of separated SBA-15 particles with unusually wide and short pores grown on silicon wafers have been fabricated in a simple single-pot-synthesis, and the formation of the films has been studied. A recipe for synthesizing mesoporous silica rods with the addition of heptane and NH4F at low temperature was used and substrates were added to the synthesis solution during the reaction. The films are ∼90nm thick, have a pore size of 10.7–13.9nm depending on the hydrothermal treatment time and temperature, and a pore length of 200–400nm. All pores are parallel to the substrate, open, and easy to access, making them suitable for applications such as catalyst hosts and gas separation. The growth of the films is closely correlated to the evolution of the mesoporous silica particles. Here, we have studied the time for adding substrates to the synthesis solution, the evolution of the films with time during formation, and the effect of hydrothermal treatment. It was found that the substrates should be added within 30–60s after turning off the stirring and the films are formed within 10min after addition to the synthesis solution. The study has yielded a new route for synthesizing mesoporous silica films with a unique morphology.

Effect of Hydrothermal Treatment on Structural Character of Palygorskite and Adsorption Efficiency for Methylene Blue

Palygorskite is widely used as an adsorbent for all kinds of pollutants in wastewater. The effect of hydrothermal treatment parameters including temperature and time on palygorskite's structural character and its adsorption of methylene blue were studied. The structures of the prepared palygorskite adsorbent were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared spectrometry (IR), and Brunauer-Emmett-Teller (BET) analysis. The results illustrate that the palygorskite fibers become shorter evidenced by TEM analysis, but there is no obvious destruction of crystal structure in XRD patterns. The BET specific surface area of palygorskite gets the largest after hydrothermal treatment at 110 °C, and then gradually reduces. Correspondingly, the adsorption capacity of methylene blue (MB) on palygorskite increases at 110 °C and then decreases till 250 °C.