Hot Water Medium Research Articles

Key Processing Factors in Hydrothermal Liquefaction and Their Impacts on Corrosion of Reactor Alloys

Despite intensive efforts to develop hydrothermal liquefaction for the conversion of wet biomass and biowaste feedstocks into valuable bio-oils, severe corrosion of conversion reactor alloys and other core components, induced by the pressurized hot water medium, catalysts, and inorganic and organic corrodants generated during the conversion process, has significantly hindered the industrial deployment of this attractive technology. In this paper, a general review of major operating parameters, including biomass feedstock types, temperature, pressure, and catalysts, was conducted to advance the understanding of their roles in conversion efficiency and the yield and properties of produced oils. Additionally, the corrosion performance of a representative constructional alloy (Alloy 33) was investigated in both non-catalytic and catalytic HTL environments at temperatures of 310 °C and 365 °C, respectively. The alloy experienced general oxidation in the non-catalytic HTL environment but suffered accelerated corrosion (up to 4.2 µm/year) with the addition of 0.5 M K2CO3 catalyst. The corrosion rate of the alloy noticeably increased with temperature and the presence of inorganic corrodants (S2− and Cl−) released from biowastes. SEM/XRD characterization showed that a thin and compact Cr-rich oxide layer grew on the alloy in the non-catalytic HTL environment, while the surface scale became a double-layer structure, composed of outer porous Fe/Cr/Ni oxides and inner Cr-rich oxide, with the introduction of the K2CO3 catalyst. From the corrosion perspective, the alloy is a suitable candidate for construction in the next phase of pilot-scale validation assessment.

Dual-functional superhydrophilic/underwater superoleophobic 2D Ti3C2TX MXene-PAN membrane for efficient oil-water separation and adsorption of organic dyes in wastewater

The incorporation of two-dimensional Ti3C2TX MXene nanoflakes into polymeric membranes has piqued researchers' enthusiasm as a way to improve the effectiveness of oil–water separation membranes. Herein, we developed a simple approach for fabricating two-dimensional Ti3C2TX MXene nanoflakes on a nanofibrous PAN membrane via vacuum filtration. The superhydrophilic/underwater superoleophobic MXene-PAN membrane showed remarkable separation performance for a diverse range of oil–water emulsions owing to its intrinsic hydrophilicity, low oil droplet adherence and regular stacking of 2D Ti3C2TX MXene nanosheets. The ultralow oil adhesion contributed to anti-oil fouling properties and outstanding recyclability, with a flux recovery ratio of about 80%. Moreover, the membrane possessed remarkable chemical stability when exposed to corrosive environmental conditions such as acid, alkali, salty and hot water medium and could also effectively separate emulsions in hostile environments. Furthermore, the MXene-PAN membrane could effectively adsorb the organic contaminants present in the oily effluent. The exceptional dual functionality of the MXene-PAN membrane, which combines outstanding separation performance and organic dye adsorption, opens up new prospects for treating oily wastewater.

A Semi‐Empirical Model for Mass Transfer in Carbohydrate Polymers: A Case of Native Cassava Starch Hydration Kinetic in Hot Water Media

AbstractDespite several works in the literature that approach modifications of starch to obtain hydrophobic characteristics, few studies have the objective of understanding and modeling the mechanisms of water absorption in starch. This paper aims to determine the parameters of a model based on mass balance to represent the process of native cassava starch hydration. For that purpose, experimental data on the hydration of natural starch subject to different temperatures are collected. Next, a semi‐empirical model obtained by the differential balance of the amount of hot water in the sample is adjusted for each temperature, and model parameters are studied. Results reveal that the mass transfer constant of the model does not suffer from a significant influence of temperature on hydration. However, the equilibrium moisture content is affected by this temperature. Through this study, it is concluded that: i) the hydration of natural starch profile has a logarithmic behavior over time, and ii) the correlation that best describes the behavior of equilibrium moisture content is linear. Results allow the construction of a generalized model for the range of studied temperatures. Finally, it is suggested the replication of the methodology applied in this paper to analyze other starch modifications.

Fluid Flow in Nanosilver-Impregnated Heat-Treated Beech Wood in Different Mediums

Specific gas permeability of beech wood was determined and compared with values obtained after nanosilver-impregnation and heat-treatment in three mediums of air, water, and water steam at 150 °C for four durations of 1, 2, 3, and 4 h. Separate sets of specimens for each group were prepared and impregnated with a 400 ppm aqueous nanosilver suspension. The results revealed that the effect of heat treatment in hot-air depended on the duration of treatment. Hydrothermal treatment generally increased gas permeability, this was attributed to the dissolving of extractives in the hot water medium, although lower duration of one hour did not significantly change permeability. Hygrothermal treatment increased gas permeability at all four durations, revealing its effectiveness as a pre-treatment to improve penetration of preservatives and fire-retardants into wood texture in wood preservation industry. High thermal conductivity of silver nanoparticles intensified the effects of heat treatment in all mediums.

PENGARUH KONSENTRASI SURFAKTAN DAN KECEPATAN PUTAR PENGADUK TERHADAP PROSES PEMISAHAN BITUMEN DARI ASBUTON

Asbuton is a rock contain of the bitumen. Asbuton can be used as road construction alternatives after extracting bitumen from the mineral. A method for separating bitumen is separation process using hot water medium. The process was carried out in a stirred tank, 200 grams of asbuton was mixed with diesel oil and added by hot chemical solution (surfactant) in the digestion tank. The separation process in the extractor was made at 900C and time set was 30 minutes. Surfactan concentration and the speed of stirrer were set according to the variable. After the process completed, the mixture was moved into a beaker glass and 500 ml hot water was added. The mixture of diesel oil and bitumen will float in the surface then the density will be measured to determine the bitumen concentration. It can be concluded that concentration of surfactant solution and speed of stirrer have the significant results. The highest recovery percentage of bitumen is 81,99 %.
 Keywords: Asbuton, Hot water, Speed of stirrer, Surfactant.

ChemInform Abstract: Green and Efficient Synthesis of Pyrazolo[3,4‐b]quinolin‐5‐ones Derivatives by Microwave‐Assisted Multicomponent Reaction in Hot Water Medium.

AbstractThe presence of 1.2 equivalents triethylamine and a reaction temperature of about 170 °C are crucial for the conversion.

Modelling the palm kernel oil extraction process in a hot-water medium

The physical process was modelled to create understanding and better assess the performance of a palm kernel oil extraction system. Mathematical models were developed to describe the extraction of palm kernel oil in hot-water from the comminuted particles. The models developed included parameters such as particle size, moisture content and charge ratio, all as a function of time. Experimental data were used to evaluate the oil recovery performance. The theoretical models were used to simulate the oil extraction process and the validity and accuracy of the predicted results were compared with experimental data. The assessment indicated that the model fitted the data from the extraction tests with coefficient of correlation (r) varying from 0.9881 to 0.9981 and absolute average percentage deviation from 4.0 to 8.9 in the range of the parameters studied.

Green and efficient synthesis of pyrazolo[3,4‐b]quinolin‐5‐ones derivatives by microwave‐assisted multicomponent reaction in hot water medium

AbstractNovel simple, efficient, and eco‐friendly synthetic procedure for preparation of pyrazolo[3,4‐b]quinolin‐5‐ones based on three‐component microwaves‐assisted heterocyclization reaction of 5‐aminopyrazoles, aromatic aldehydes, and dimedone in hot‐water medium was developed. The new method allows obtaining target heterocycles in good and excellent yields and with high degree of purity. J. Heterocyclic Chem., (2011).

A device for the extraction of palm kernel oil in a hot-water medium

A device for the extraction of palm kernel oil in a hot-water medium

Liquid-Liquid Direct Contact Heat Exchange Using a Perfluorocarbon Liquid for Waste Heat Recovery. Heat Transfer Characteristics Obtained with Perfluorocarbon Droplets Descending in a Hot Water Medium.

This paper has dealt with the heat transfer characteristics of a liquid-liquid direct contact operation in which a Perfluorocarbon (PFC) liquid was released in a hot water stream, which was a low-grade heat source such as urban sewage, for the purpose of heat recovery from it. The paper reported on a set of experiments in which a PFC liquid (1800kg/m3 at 20°C) was continuously injected from a downward-facing single nozzle into a slow and upward flow of hot water and it was disintegrated into a lot of droplets and then they were heated from the ascending hot water. The experimental results revealed that the size distribution and flow behavior of the droplet ensembles exerted an influence on the coefficient of overall heat transfer between the droplet ensembles and hot water and also the temperature effectiveness for the droplet ensembles.

Liquid-Liquid Direct Contact Heat Exchange Using a Perfluorocarbon Liquid for Waste Heat Recovery. Heat Transfer Characteristics obtained with Perfluorocarbon Droplets Descending in a Hot Water Medium.

This paper deals with the heat transfer characteristics of a liquid-liquid direct contact operation in which a Perfluorocarbon (PFC) liquid is released in a hot water stream, a low-grade heat source such as urban sewage, for the purpose of heat recovery from it. The paper reports on a set of experiments in which a PFC liquid (1800 kg/m3 at 20°C) was continuously injected from a single, downward-facing nozzle into a slow, upward flow of hot water to be disintegrated into droplets descending in, and thereby heated from the water flow. The results of the experiments show how the size distribution and the translational motions of the droplets affect the overall coefficient for the water-flow-to-droplets heat transfer and also the temperature effectiveness for the droplets.