Effect of composition on the ability to form SiC/SiO2-C composite from rice husk and silica gel

Do Quang Minh,Tran Van Khai,Huynh Ngoc Minh,Nguyen Vu Uyen Nhi,Kieu Do Trung Kien 한양대학교 세라믹연구소 2021 Journal of Ceramic Processing Research Vol.22 No.2

Rice husk is a waste product of agricultural production of rice. Every year, the agricultural production of Vietnam emits about10 million tons of rice husks. Rice husks are usually treated by burning method or discharged into rivers, causing manynegative impacts on the environment. In this study, the rice husk/silica gel ratio components were investigated to form SiC/SiO2-C composite in a CO2 environment at 1000 oC for 60 min. The products after pyrolysis were determined SiC, SiO2, andfree C contents according to ISO 21068-2: 2008 standards. The functional groups and mineral composition of composites wereanalyzed by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The microstructure and elementdistribution of them were observed by scanning electron microscope (SEM) and Energy-dispersive X-ray (EDX) mapping. Theresults showed that the optimum rice husk/silica gel ratio to form SiC/SiO2-C was 1.4/1. The sample after pyrolysis hadchemical composition including 14% SiC, 63% SiO2, 23% free C (%wt.) and the phase composition including amorphouscarbon, β-SiC, 6H-SiC, 4H-SiC, cristobalite. Composite SiC/SiO2-C can apply to advanced friction systems. This can be seenas an effective method to treat rice husk waste and improved the economic value of rice plants.

Effects of non-vertical linear motions of a hemispherical-float wave energy converter

Do, Hoang-Thinh,Dinh, Quang-Truong,Nguyen, Minh-Tri,Phan, Cong-Binh,Dang, Tri-Dung,Lee, Seyoung,Park, Hyung-Gyu,Ahn, Kyoung-Kwan Elsevier 2015 Ocean engineering Vol.109 No.-

<P><B>Abstract</B></P> <P>The hydraulic power-take-off mechanism (HPTO) is one of the most popular methods in wave energy converter (WECs). However, the conventional HPTO with only one direction motion has some drawbacks which limit its power capture capability. This paper proposes an <I>adjustable slope angle wave energy converter</I> (ASAWEC) and investigates the effect of slope angle on the performance of the proposed wave energy converter to find the optimal slope angle with the purpose to increase the power capture capability as well as energy efficiency. A mathematical model of components from a floating buoy to a hydraulic motor was modeled. A small scale WEC test rig was fabricated to verify the power capture capability and efficiency of the proposed system throughout experiments.</P> <P><B>Highlights</B></P> <P> <UL> <LI> This paper proposed an adjustable moving angle wave energy converter (AMAWEC). </LI> <LI> Mathematical model of AMAWEC was presented and simulated. </LI> <LI> An AMAWEC test rig were fabricated to do the experiment in variety of wave conditions and moving angle in the water tank. </LI> <LI> The effect of moving angle on the performance of a wave energy converter was investigated to find the optimal moving angle in each wave condition. </LI> <LI> Finally, the effectiveness of AMAWEC has been verified by experimental results. </LI> </UL> </P>

Simulation and Experimental Study on the Steady Conduction Solution for Continuous Rheo-Casting for A356 Alloy

Do Minh Duc,Nguyen Hong Hai,Pham Quang 대한금속·재료학회 2017 대한금속·재료학회지 Vol.55 No.3

Computational fluid dynamic modeling of a continuous rheo-casting technology was conducted, consistent with the manufacturing of 3 -thin plates made of aluminum alloy A356. The A numerical simulation on of the stabilizing time of the material crystallization was carried out using the ANSYS FLUENT code. Solidification and melting models were simulated with heat transfer and solid-liquid phase transformation involving the latent heat of crystallization were simulated. The calculated temperature distribution and the evolution of cooling rate through the material were examined and used to clarify their influence on microstructure, and further investigated with hardness testing. The thickness of the mushy zone was determined for the steady conduction solution of the continuous rheo-casting process.

Simultaneous degradation of 2,4,6-trinitrophenyl-N-methylnitramine (Tetryl) and hexahydro-1,3,5-trinitro-1,3,5 triazine (RDX) in polluted wastewater using some advanced oxidation processes

Do Ngoc Khue,Tran Dai Lam,Nguyen Van Chat,Vu Quang Bach,Do Binh Minh,Vu Duc Loi,Nguyen Van Anh 한국공업화학회 2014 Journal of Industrial and Engineering Chemistry Vol.20 No.4

Here we report the study on the utilization of several advanced oxidation processes such as electro-oxidation and Fenton process in simultaneous treatment of two nitramine explosives: 2,4,6-trinitrophenyl-N-metylnitramine (Tetryl) and hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX). The preliminary tests indicated that the electrolytic method using a TiO2/IrO2/RuO2-coated electrode could rapidly degrade Tetryl but not RDX. While the addition of certain amount of H2O2 induced an increase of Tetryl degradation yield but had insignificant effect on RDX decomposition, the use of Fenton’s reagent showed an enhanced efficiency in degradation of both nitramines. It can be concluded that among tested processes, Fenton process is the most effective for treatment of nitramine-containing wastewaters.

Study on sintering process of woodceramics from the cashew nutshell waste

Kieu Do Trung Kien,Phan DinhTuan,Toshihiro Okabe,Do Quang Minh,Tran Van Khai 한양대학교 세라믹연구소 2018 Journal of Ceramic Processing Research Vol.19 No.6

In this study, the sintering mechanism of woodceramics (WCs) from cashew nut shell waste (CNSW) was studied by analyzingchemical reactions and structural changes during the sintering process of of CNSW powder, liquefied wood and green bodiesof WCs at 900 oC for 60 minutes in the CO2 atmosphere. The chemical and structural properties of the products wereinvestigated by X-ray diffraction (XRD), Raman spectroscopy, Fourier Transform Infrared (FTIR), and scanning electronmicroscope (SEM). The results showed that the decomposition reactions of liquefied wood and CNSW occurred simultaneouslyto form the hard carbon and the soft carbon at high temperature. The sintering mechanism of WCs has been presented.

Numerical Simulation and Experimental Analysis of The Equal Channel Angular Pressing of Pure Titanium

( Pham Quang ),( Do Minh Nghiep ) 대한금속재료학회(구 대한금속학회) 2016 대한금속·재료학회지 Vol.54 No.3

The plastic deformation behavior of pure Ti during equal channel angular pressing (ECAP) is simulated using the three-dimension finite volume method and is experimentally investigated. The calculated effective strain and effective stress distributions and histories are analyzed to understand the local and global deformation characteristics. The predicted plastic deformation behavior of the Ti workpiece during the ECAP process was compared with the theoretical total strain for every pass at RAM speed v of 10 mm/s and at constant temperature of 400 ℃. The simulated strain and stress distributions are homogenous in the central region of the ECAP processed Ti. The experimental ECAP performed with four, eight, and twelve passes at 400 ℃ results in refined grain sizes of approximately 5-10 μm, 0.4-0.5 μm and 0.1-0.2 μm, respectively.

Effect of the sintering temperature on the carbonization behaviour of woodceramics from the cashew nut shell waste

Kieu Do Trung Kien,Do Quang Minh 한양대학교 청정에너지연구소 2023 Journal of Ceramic Processing Research Vol.24 No.1

Woodceramics is carbon ceramics with porous structures that can be used in many technical fields. In this study,woodceramics was prepared by mixing cashew nut shell waste (CNSW) and liquefied wood with a ratio of 1/0.6 and thensintered in an inert atmosphere at 700 oC-1200 oC. The influence of sintering temperature on the carbonization behavior offormed woodceramics was determined by X-ray diffraction, Fourier transforms infrared spectroscopy, Isotope Ratio MassSpectrometry measurement, and Scanning Electron Microscope/ Energy Dispersive X-Ray Analysis techniques. Theexperimental results showed that the carbon content increased when the sintering temperature increased. In addition to theincreased carbon content, the degree of graphitization of woodceramics also increased. It is represented by an increasedintensity of the (002) peaks and a decrease in the d002 value on the X-ray diffraction patterns. The SEM/EDX results alsoshowed that appeared small graphite particles in the amorphous background at 1000 oC-1200 oC. However, the d002 value ofthe samples is only in the range of 0.3339-0.4094 nm, so the structure of the formed carbon is a non-graphite structure.

Hepatic Artery Thrombosis Associated with Fungal Infection: Report of Two Cases

( Dang Do Hai ),( Nghia Nguyen Quang ),( Thang Le Quang ),( Khai Ninh Viet ),( Tuan Tran Minh ),( Phuong Tran Ha ),( Tuan Hoang ),( Dung Tran Dinh ) 대한간학회 2023 춘·추계 학술대회 (The Liver Week) Vol.2023 No.1

physical properties of La0.67Ca0.33Mn0.9TM0.1O3 [TM = Fe, Co, Ni] and their spin dynamics in the paramagnetic regime studied by EPR

Pham Hong Quang,유성초,Do Hong Minh,Huynh Thanh Nhan,Nguyen Huy Sinh 한국물리학회 2004 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.45 No.3

Substitution of Mn by Fe, Co, and Ni ions suppresses double exchange (DE), leading to a reduction in ferromagnetic interaction, or equivalently to lower values of Curie temperature, TC. The intensity of the electron paramagnetic resonance (EPR) line decreases exponentially with temperature, and the temperature dependence of EPR linewidth undergoes a minimum near TC. The activation energy values, Ea, derived from the temperature dependence of EPR line intensity, are equal to 0.074 eV, 0.093 eV and 0.086 eV for TM = Fe, Co, and Ni, respectively. In the case of cobalt substitution, an anomaly in the thermal evolution of the EPR linewidth has been observed. We attribute the cause of this anomaly to a Jahn-Teller transition or an electronic phase separation.

Ag-doped graphitic carbon nitride photocatalyst with remarkably enhanced photocatalytic activity towards antibiotic in hospital wastewater under solar light

Nguyen Le Minh Tri,김지태,Bach Long Giang,T.M. Al Tahtamouni,Pham Thi Huong,이창하,Nguyen Minh Viet,Do Quang Trung 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.80 No.-

In this study a novel Ag-doped graphitic carbon nitride (g-C3N4) photocatalyst was synthesized and appliedas high efficientmaterial under solarlight towardsemerging antibiotic pollutantin hospital wastewater. Thetetracycline (TC) was chosen as a target pollutant and the content of Ag doping at 3 mmol revealed thehighest photocatalytic degradation efficiency of TC (96.8%) after 120 min under solar light irradiation. Thephotoluminescence and UV–vis analysis confirmed the enhancement of charge separation and transfer inthe graphitic carbon structure after Ag-doping. The removal efficiency of TC using g-C3N4 and Ag-doped g-C3N4 (AgCN) underdark conditions was only 25.6 and 31.8%, respectively. While under solarlight conditions,the removal efficiency of TC increased to 68.3 and 96.8% for g-C3N4 and AgCN, respectively. The reusabilityprocess showed that AgCN displayed extremely high stability after 6 cycles without significant drop inantibiotic degradation efficiency. The application of AgCN was tested for treatment of TC from hospitalwastewater and it showed high removal efficiency of 89.6% within 120 min reaction time. In addition, theintermediatesgeneratedandreductionof total organiccarbon(TOC)duringthephotocatalyticreactionweredetected to support information of possible TC removal mechanism.