Influence Of Hydrothermal Treatment Research Articles

From mixed brookite/anatase TiO2 nanopowder to sodium titanates: Insight into morphology, structure, and photocatalytic performance

A method to obtain sodium titanate nanoribbons starting from a mixture of brookite and anatase TiO₂ nanopowder is described. As-prepared TiO2 nanopowder with a major brookite phase was used as a precursor in an alkaline hydrothermal approach, where the temperature was kept at 200 °C. The influence of hydrothermal treatment and consequent annealing temperature (T = 500 °C) on the crystal structure, phase composition, and morphology of samples were investigated by X-ray powder diffraction (XRPD), Raman and FTIR spectroscopy, and electron microscopy techniques (FESEM, HRTEM). All these methods point out that the hydrothermally treated sample, containing the NaTi3O6(OH)(H2O)2, Na2Ti3O7, and Na2Ti9O19, is dominated by layer-structured sodium hydroxititanate dihydrate. The annealing leads to the formation of rare sodium titanates, Na3Ti6O13 and Na2Ti9O19, with tunnel structures where the hexatitanate with increased sodium content prevails. The photocatalytic activity of synthesized nanostructures was tested in the degradation process of Reactive Orange (RO16) azo-dye upon UV excitation. It appears that photocatalytic activity is lower after hydrothermal treatment, but subsequent annealing makes sodium titanate nanoribbons faster in the degradation of RO16. The research implies that these sodium titanate nanostructures are promising photocatalytic materials and should be considered in the future for removing different pollutants from water.

Influence of hydrothermal treatment on hemicellulose structure in Cryptomeria japonica

The influence of hydrothermal treatment (HTT) on the hemicellulose, i.e. glucomannan/galactoglucomannan (GM/GGM) and arabinoglucurono-xylan (AGX) in Japanese cedar was examined using mild temperatures (95 °C and 120 °C) for its kiln drying. Based on infrared spectra, only a slight change due to HTT was observed in the hemicellulose chemical structure. The quantitative changes of the major chemical components including lignin, cellulose, and hemicellulose also exhibited slight differences among samples. However, the molecular chain-length composition of GM/GGM and AGX in the cell walls decreased clearly with HTT, as well as with an increase in temperature. Also, it was found that the strength of the interaction between cellulose and hemicellulose molecules such as GM/GGM and AGX in cell walls decreased depending on the increase in HTT temperature. These results showed that the polymeric structure of GM/GGM and AGX was degraded by hydrolysis at 95 °C of HTT and proceeded further at 120 °C of HTT.

The influence of hydrothermal treatment on TiO2 nanostructure films transformed from titanates and their photoelectrochemical water splitting properties

Anatase non-stoichiometric TiO2 nanostructure films transformed from titanates were fabricated using the alkaline hydrothermal method at different treatment durations. The field emission scanning electron microscopy (FESEM) images demonstrated the morphological change of TiO2 from nanosheets to nanowires. The X-ray diffraction (XRD) patterns confirmed the anatase phase for TiO2 nanostructures. The UV–vis-NIR measurement indicated the decline in visible light absorption with increasing treatment duration. For the photoelectrochemical (PEC) measurement, four hours hydrothermal synthesis TiO2 annealed in air at 500 °C for 90 min showed the optimal photocurrent response with the maximum photocurrent density of 149.1µA/cm2 at 0.8 V vs. Ag/AgCl, which is attributed to the narrow bandgap (3.22 eV), improved carrier density (4.806×1018 cm−3) and longest lifetime of carriers (3.2 ms). Thus, nanosheet morphology was found to be more superior than nanowire morphology and a relatively short hydrothermal treatment duration was beneficial to PEC water splitting properties. In addition, for superior PEC performance, appropriate nanosheet density and surface area are necessary. The results demonstrated that TiO2 nanostructures transformed from titanates could be used for PEC application and the PEC characteristics could be tuned and modified for better water splitting performance.

Alumina binder effects on the hydrothermal stability of shaped zeolite-based catalyst bodies

The influence of hydrothermal treatments and alumina binder on the properties and catalytic performance in the methanol-to-hydrocarbon reaction of different zeolite–alumina catalyst extrudates was characterized using a combination of ex situ, in situ and operando techniques.

Impacts of Hydrothermal Treatments on the Morphology, Structural Characteristics, and In Vitro Digestibility of Water Caltrop Starch.

The influence of hydrothermal treatments on the structural properties and digestibility of water caltrop starch was investigated. Scanning electron microscopy (SEM) showed some small dents on the surface of starch granules for samples treated with heat moisture treatment (HMT), but not for samples treated with annealing (ANN) which generally showed smoother surfaces. The gelatinization temperature of starch was generally increased by hydrothermal treatments, accompanied by a trend of decreasing breakdown viscosity. These results implied the improvement of thermal and shearing stability, particularly for HMT in comparison to ANN. After being cooked, the native and ANN-modified water caltrop starch granules were essentially burst or destroyed. On the other hand, the margin of starch granules modified by HMT and dual hydrothermal treatments remained clear with some channels inside the starch granules. X-ray diffraction revealed that the crystalline pattern of water caltrop starch changed from the CA-type to the A-type and the relative crystallinity reduced with increasing moisture levels of HMT. Results of ANN-modified water caltrop starch were mostly similar to those of the native one. Moreover, water caltrop starch modified with HMT20 and dual modification contained a pronouncedly higher resistant starch content. These results suggested that HMT, ANN, and dual modification effectively modified the functional properties of water caltrop starch.

Characterization of Nanostructured Mn-Zn Ferrites Synthesized by Coprecipitation Method Using CTAB

In this work it was investigated the influence of CTAB surfactant concentration on the synthesis of the compound Mn0.75Zn0.25Fe2O4 by the coprecipitation method. It was also compared the influence of hydrothermal treatment on the synthesized materials. The magnetic properties were characterized by AC susceptometry for the determination of the magnetic susceptibility and magnetic density energy. The phases, crystal structure and morphology of the nanoferrites were determined by Rietveld analysis of X-ray diffraction data. It was found the presence of two phases: Franklinite and Akaganeite and it was shown that the samples synthesized only by coprecipitation presented the tendency to increasing the crystallite sizes of the akaganeite phase and decreasing of crystallite sizes of the Franklinite phase as a function of CTAB concentration. The samples submitted to subsequent hydrothermal treatment presented a tendency to decreasing the crystallite sizes of both phases and increasing in Franklinite phase fraction, compared to the samples synthesized only by coprecipitation, suggesting that the hydrothermal treatment was effective in obtaining nanostructured materials of smaller particles.

Influence of hydrothermal treatment on structural property of NiZrAl mixed-metal oxides and on catalytic steam reforming of glycerol for hydrogen production

NiZrAl layered double hydroxides (LDH) precursors were synthesized by co-precipitation and homogeneous precipitation processes. The introduction of hydrothermal treatment into crystallization showed its significant influences on structure of LDH as well as mixed-metal oxides after thermal decomposition. The characterization results showed that the catalysts prepared by hydrothermal synthesis involved bigger pore diameter of ca. 13.5 nm and wider pore size distribution of 2–60 nm, and hydrothermal treatment was helpful to enhance the reduction of NiO species weakly interacted with support and to enhance the interaction among the metal oxides. Although the Ni dispersion, the surface area as well as the ability of anti-sintering were evidently improved, the ability of coke resistance decreased by 2 times for samples prepared by co-precipitation and by nearly 10 times for the ones prepared by homogeneous precipitation due to the enlarged pores. The maximum value of conversion to gaseous products (96.5%) and minimum deposited coke (36 mgc/gcat.) were achieved on NiZrAl-u sample.

Improving the process of hydrothermal treatment and dehulling of different triticale grain fractions in the production of groats

The influence of hydrothermal treatment (grain moistening) and dehulling duration on the yield and quality of groats from different fractions of triticale grain was studied. Comparative analysis of groats yield and its culinary quality at different grain moisture, depending on its fractions, was performed. The degree of the influence of the studied factors on the yield and quality of triticale groats was determined. The influence of dehulling duration, the size of a triticale caryopsis and grain moisture content is reliable. These factors significantly influenced the groats yield and quality. In addition, the influence of the duration of grain dehulling was the highest. The highest groats yield was obtained at the dehulling duration of 20 s, the lowest – at dehulling for 180 s. The social survey was conducted and the main priorities for buyers of cereal products were established. It was proved that while choosing food, consumers pay the most attention to culinary characteristics of the finished product. It was established that it is optimal to dehull triticale grain for 100 s. The application of such parameters of treatment makes it possible to obtain the yield of whole groats of 88.8 % with the culinary quality of 6.7 points. The groats quality meets the requirements of DSTU 76992015 Wheat Groats. Technical specifications. Based on the research, it was established that the separation of the triticale grain into fractions that differ in their geometric properties, in particular, thickness, is effective. The peculiarities of groats yield, depending on the triticale grain fraction, were determined. Application of hydrothermal treatment of triticale grain (moistening up to 14.0 %) makes it possible to increase the groats yield up to 88.7 %. The treatment of the fractions with grain thickness less than 2.4 mm ensures the groats yield up to 87.8 %. The groats yield during dehulling the grain, which has a thickness of more than 2.4 mm, is from 88.8 to 89.1 %. To produce the groats from triticale grain, it is advisable to use the grains that have a thickness of 2.8 mm or more. The optimum duration of dehulling is 100 s. To increase the overall culinary assessment by 1 point, it is recommended to increase the duration of dehulling a large grain up to 140 s. This method differs from the classical one by the fact that it uses a large grain fraction with the lower moisture content. The developed recommendations can be used by grain processing enterprises during processing triticale with the view to intensifying the production.

Influence of hydrothermal treatment on selenium emission-reduction and transformation from low-ranked coal

One of the key environmental limitations in coal usage is selenium emission whose removal is focused in this study. We employed hydrothermal treatment to remove Se element and upgrade low rank Huainan coal at 200–300 °C. Pyrolysis temperature given during coal treatment was evaluated to simulate coal transformation into high-rank industrial grade by emphasizing O/C ratio, removal of oxygen functional groups and moisture and chemical structure stability. Following hydrothermal treatment, different characterization techniques including XPS, FTIR, XRD and Raman spectroscopy were used to determine the chemical structure of coal. Findings revealed that hydrothermal treatment process has an important influence on the crystalline structures of low rank coals. The results of XRD and Raman spectroscopy analysis demonstrated much graphitized and aromatic microcrystalline structure. The chemical structure developed was orderly, stable and dense. Selenium XPS spectra comprising of 3D peaks has confirmed several oxidation states including selenide, selenates and oxide species. The removal proportion of Se was significant and increased up to 50.7% with increased HTT temperature (300 °C). This study provides some unique findings pertaining to solubility of sub-critical water and rate of change in pyrolysis temperature as determinant factors in the removal of Se. Our simulation model further concludes that transformation of low rank coal into high rank is a function of temperature treatment coupled with optimization of fixed carbon. We infer that hydrothermal treatment derived coal possesses sufficient lucid attributes to be considered as environmentally safe fuel.

Ultrasonic effect on the photocatalytic degradation of Rhodamine 6G (Rh6G) dye by cotton fabrics loaded with TiO2

The effect of sonication on the photodegradation of Rhodamine 6G (Rh6G, a fluorone dye) using woven cotton fabrics decorated with TiO2 nanoparticles (NPs) has been investigated. TiO2 NPs were synthesized in situ by sol–gel method in the presence of cotton textile and then hydrothermally treated. TiO2-loaded fabrics were treated ultrasonically to test adhesion to- and properties of the NPs on the fabrics. We demonstrate good adhesion and a good stability of the NPs of TiO2. Moreover, sonication substantially improved the distribution on the surfaces and hence enhanced the fabrics catalytic activity. Either under UV or simulated sunlight, ultrasonicated fabrics were found to have a high photocatalytic activity towards Rh6G, used as a model dye. SEM, XPS, UV–Vis and FTIR spectroscopy, as well as ground state diffuse reflectance and laser induced luminescence were used to characterize fabrics/TiO2 samples in terms of topography, surface composition, influence of hydrothermal treatment on photocatalytic activity, stability of TiO2 NPs, electro-optical properties of the modified fabrics, as well as the effect of ultrasonication on the photodegradation of Rh6G. This work paves the way to a larger scale improvement of the photocatalytic performances of TiO2-loaded cotton fabrics by post-sonication.

Influence of hydrothermal treatment on the structural and digestive changes of actomyosin.

Heat treatment induces both structural and digestive change of meat protein. However, little has been revealed regarding the associations between structural changes and digested peptides of myofibrillar proteins. This work investigated the effects of heat treatment on the structures and in vitro digestibility of actomyosin, and the peptidomics of the digests were analyzed using liquid chromatography tandem mass spectrometry (LC-MS/MS). Heat treatment resulted in unfolding and aggregation behavior of actomyosin according to the results of surface hydrophobicity and particle size. Formation of disulfide bonds and increase in carbonyl groups that occurred during heat treatment of actomyosin indicated the oxidation of specific residues. Unfolding behavior could elevate digestibility of actomyosin by exposing residues, based on the identification of peptides in digests of actomyosin using LC-MS/MS. However, the disulfide bond proved to reduce the action of digestive proteases, since the peptides number (increased from 56 to 86 in sample heated at 70 °C for 30 min) and peptides intensity in digests largely increased after the addition of dithiothreitol (DTT). Heating at higher temperature (100 °C) induced severer aggregation and oxidation, which resulted in lower digestibility of actomyosin than that heated at 70 °C by burying or damaging partial cleavage sites for digestive proteases. This work highlights the huge influence of heat treatment on the multi-scale structures of myofibrillar proteins, which largely changed the peptides composition in protein digests. © 2019 Society of Chemical Industry.

Improvement of the process of hydrothermal treatment and peeling of spelt wheat grain during cereal production

The influence of hydrothermal treatment (grain moistening, steeping) and peeling duration on the yield and quality of spelt wheat cereal was studied. The mechanism of the influence of the studied factors on the formation of cereal and culinary quality of the product was established. A comparative analysis of the yield and quality of cereals after hydrothermal treatment at actual humidity content from 13.0 to 14.0 % was performed. Due to the hydrothermal treatment, the properties of the endosperm and shells change significantly. This leads to an increase in the strength of endosperm and formation of higher yield of the finished product. The influence of peeling duration and hydration gradient on the yield of cereal and middling is reliable. The influence of duration of spelt wheat steeping on this process was insignificant. Application of grain damping (humidity content of 15.0–16.0 %) makes it possible to increase the yield of cereal from 88.6 % to 91.7 %. Culinary quality does not change in this case. The obtained mathematical models of the influence of damping steeping, peeling of grain on the yield and quality of cereals are linear. Their accuracy is proved by the high determination coefficients ( R 2 =0.97‒0.98) and by the absence of autocorrelation of residues. In the technology of production of cereals from spelt wheat the recommended method of hydrothermal treatment implies its damping up to 15.0 % of moisture content, which makes it possible to increase the yield of cereals by 3.1 %. The difference from the classical method is the absence of the grain steeping phase before peeling. Damping of spelt wheat grain up to 15.0 % with peeling duration of 160 s is optimum. The proposed way of treatment allows getting 86.5 % of cereals with culinary quality of 8–9 points. The developed recommendations may be used by food industry enterprises during conducting marketing activities or production intensification.

Improved template – ion exchange synthesis of Cu-nanostructured molecular sieves

Abstract A series of M41S type mesoporous molecular sieves modified with copper were synthesized through Template-Ion Exchange (TIE). The influence of hydrothermal treatment and mixing time at room temperature over the solids structural and chemical properties was evaluated in detail for a single Cu content. Characterization of the materials was carried out through various techniques: XRD, N2 adsorption-desorption, SEM, XPS, atomic absorption, UV–vis DR and TPR. It was found that different stirring times at room temperature had no significant influence over the physical and chemical characteristics of the final solid. However, hydrothermal treatment had a slight effect over the materials structure and metallic species distribution. In order to assess copper content influence, two other non-treated solids with different metallic contents were synthesized, characterized, and compared with hydrothermally treated samples. The catalytic performance of the hydrothermally treated and non-treated materials was tested in the liquid phase oxidation of limonene employing hydrogen peroxide (H2O2) as oxygen donor, an important fine chemical reaction. Only one of the evaluated Cu contents exhibited a minor difference in catalytic activity according to the applied synthesis conditions. Hence, a simple TIE procedure without hydrothermal treatment can be employed for the synthesis of Cu-MCM materials. By suppressing hydrothermal treatment, it is possible to save around 10% of the total energy requirement for the complete synthesis process.

Influence of hydrothermal treatment on physicochemical characteristics of white beans seeds (<i>Phaseolus vulgaris</i>) produced in Côte d’Ivoire

Influence of hydrothermal treatment on physicochemical characteristics of white beans seeds (<i>Phaseolus vulgaris</i>) produced in Côte d’Ivoire

Influence of hydrothermal treatment on the mechanical and environmental performances of mortars including MSWI bottom ash

Nowadays, in many countries the household waste is more and more incinerated, converting refuse in municipal solid waste incineration bottom ash (MSWI BA). A main concern related to the reuse of BA is linked to the leaching of contaminants, such as heavy metals and salts, to the surrounding environment. To limit this leaching, BA is applied as aggregate in the construction field, since the hydration products of cement are able to immobilize contaminants. Although not always suitable from an environmental point of view, a hydrothermal treatment (HT) can be applied to further increase the contaminants retention, as it stimulates the formation of tobermorite and it densifies the cement matrix. However, not many studies have investigated the influence of HT on cement based mortars and even less have been conducted concerning the optimization of the HT conditions. This study investigates the minimum HT duration for the maximization of mechanical performances and minimization of the environmental impact, for mortars including 25% BA, as sand replacement. The optimal autoclaving duration is found to be 6 h HT, which increases the compressive strength by 30% and it improves the retention of ions as Ba2+, Zn2+, and Cl− by 90%, 60% and 32%, respectively, compared to the standard cured sample. For longer treatment (8 h), the HT is not beneficial, since the leaching of contaminants increases due to the decomposition of reaction products as AFt and AFm.

Influence of Hydrothermal Treatment on Crystalline Form of SiO2 Synthesized by Sol-Gel Method

The hydrothermal method and traditional sol-gel process for the synthesis of SiO2 particles were comparatively studied. For the synthesis of SiO2, tetraethyl orthosilicate (tetraethoxysilane or TEOS) and ammonium chloride (NH4OH) (as a catalyst) were used. SiO2 was prepared by the TEOS hydrolysis reaction at room temperature and hydrothermal treatment. Morphology and structure of the final products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectrum (FT-IR) and scanning electron micrograph (SEM). It was found that SiO2 product synthesized by the TEOS hydrolysis reaction at room temperature has an amorphous phase. XRD analysis shows the presence of an amorphous halo - a strong peak at Bragg angle 21 °-22 °. The hydrothermal treatment leads to crystallization of the material.

Influence of hydrothermal treatment on inductance of water–peat suspension

The influence of hydrothermal carbonization on electrochemical properties of water–peat suspension was studied. It was found that the suspension acquires property of electrolyte when produced by hydrothermal carbonization. due to the washing out a part of the mineral component and possibly a partial conversion of the organic part.

Influence of hydrothermal treatment on the structural modification of spent grain specific carbohydrates and the formation of degradation products using model compounds

Brewer’s spent grain (BSG) constitutes various valuable carbohydrates that may contribute to a healthy diet. These components may be obtained from BSG via hydrothermal treatment (HT), a procedure for dissolving water-inextricable carbohydrates. The objective of this study was to investigate HT as an environmentally friendly technology for extracting high-molecular-weight fiber with proven beneficial effects on human health. Cellulose, β-glucan, and arabinoxylan (AX) served as model substances and were subjected to auto-hydrolysis at different temperatures and reaction times. The results were evaluated in terms of structural and chemical characteristics. When the treatment temperature was increased, the original weight-average molar mass of AX (370 kDa) and β-glucan (248 kDa) decreased gradually (<10 kDa), and the molar mass distribution narrowed. Further investigations focused on the heat-induced formation and elimination of monosaccharides and undesirable by-products. The concentrations of by-products were successfully described by kinetic models that can be used to optimize the hydrolysis process.

Influence of hydrothermal treatment on filterability of fine solids in bitumen froth

Bitumen froth generated during the oil recovery operation from Athabasca oil sands needs to be cleaned to remove water and fine mineral solids for subsequent bitumen upgrading or pipeline transport. Two currently used bitumen froth cleaning methods, naphthenic froth treatment (NFT) and paraffinic froth treatment (PFT), either cannot generate market-spec bitumen froth (NFT) or causes losses of bitumen (PFT). In this study, a combination of hydrothermal treatment, venting and filtration was investigated to clean the bitumen froth. Laboratory hydrothermal treatment was conducted at 300–420°C for 0–180min. The filterability of fine solids was quantitatively characterized by room-temperature filtration or hot filtration at 200°C. Mineralogical composition and particle size distribution of the untreated and treated fine solids were determined by quantitative X-ray diffraction using RockJock and focused beam reflectance measurement (FBRM) particle size analyzer. The microscopic observation of clay particle stacking behavior at the filter cake-filter medium interface was made by scanning electron microscope (SEM). The results show that hydrothermal treatment followed by venting and filtration is an effective way to remove water and fine solids from bitumen froth: the water content was reduced from 14wt% to 0.03wt%, and the fine solids content was reduced from 8wt% to 0.08wt% by hot filtration at 200°C using a 0.5μm pore size stainless steel filter medium. After hydrothermal treatment, no noticeable changes were observed to the clay mineralogy and fine solids particle size. However, the platy clay particles at the filter cake-filter medium interface turned from preferential orientation to random orientation due to the attachment of numerous ultrafine particles on the basal surface of the clay, increasing the porosity of the filter cake and facilitating the filtration. Such a change in the filter cake was hypothesized to be caused by the re-structuring of the organic-mineral aggregates into the ultrafine-particle-coated platy clays, releasing the organics and the ultrafine solids during the hydrothermal treatment. The released ultrafine solids then adsorbed onto the clay platelets. It was indeed observed that the total organic carbon content of the bulk fine solids decreased from 14.7wt% to 10.3wt%, but the carbon concentration on the fine solids surface increased from 35.6at.% to 47.7at.%.

Influence of Hydrothermal Treatment on Wheat for Milling

In this paper there are observed some aspects regarding wheat conditioning which has as target phisico-mechanical and structural properties changing, in order to improve the quality of flower obtained by milling. It is presented the research methods which include the use of a milling stand and a hydrothermal treatment device of wheat. The results of the experimental attempts are shown in the tables and graphics and the conclusions obtained are presented at the end of the paper.