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Van Tran, Thuan,Nguyen, Duyen Thi Cam,Le, Hanh T.N.,Bach, Long Giang,Vo, Dai-Viet N.,Dao, To-Uyen T.,Lim, Kwon Taek,Nguyen, Trinh Duy Elsevier 2019 Journal of environmental chemical engineering Vol.7 No.5
<P><B>Abstract</B></P> <P>Discharge of nonsteroidal anti-inflammatory drugs (NSAIDs) from wastewater has been increasingly alarmed, led to the advent of the treatment techniques. Among these methods, adsorption is regarded as a tunable and green approach with the utilization of mesoporous carbon (MC) as an efficient and recyclable adsorbent. Herein, we described the strategy for the synthesis of novel MC from Fe-MIL-88B as a self-sacrificial template. Three thermolysis temperatures (550, 750, and 950 °C) were investigated to compare the structural characteristics and absorbability towards selected NSAIDs compounds including diclofenac sodium (DCF), aspirin (APR), and ibuprofen (IBU). Effect of contact time (0–480 min), concentration (10–40 mg/L), pH (2–10), and MC dosage (0.1–0.5 g/L) was systematically studied. Kinetic and isotherm models were also used to find out the adsorption mechanism and behavior of NSAIDs pharmaceutical over MC materials. Proposed mechanism and recyclability test were rigorously studied to gain more insight into how the NSAIDs molecules adsorb on the MC materials and their potential towards drug treatment.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Effect of thermolysis temperature on characteristics and absorbability towards anti-inflammatory drugs was conducted. </LI> <LI> Kinetic, isotherm, and recyclability experiments were systematically studied. </LI> <LI> Adsorption mechanisms including H-bond, π–π interaction, metal–oxygen bridging, and electrostatic attraction were rigorously proposed. </LI> <LI> Outstanding adsorption capacity (∼144 mg/g), and excellent reusability were monitored with Fe-MIL-88B-derived mesoporous carbon. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Cascaded Single-Phase Boost Inverter Using High Frequency Transformer
( Van Thuan Tran ),( Tan Tai Tran ),( Minh Khai Nguyen ),( Hong Woo Lim ),( Won Bae Kim ) 조선대학교 공학기술연구원 2016 공학기술논문지 Vol.9 No.1
Quasi-switched boost inverter was investigated to replace Z-source inverter and switched-boost inverter in the field of low power applications because it uses one-LC-pair less than Z-source inverter. In this paper, we suggest the configuration of H-bridge quasi-switched boost inverter based on high frequency transformer (H-qSBI) to improve voltage gain factor. The proposed topology contains the same devices like switched boost inverter, where the active switch is replaced by an H-bridge inverter. This paper focuses on analyzing quasi-switched boost inverter (qSBI) implementation and simulating the performing results of cascaded single-phase dual-inverter using high frequency transformer by PSIM simulation software. The results are tested by an input DC voltage of 36 V to generate an AC voltage of 220Vrms/50Hz.
Van Thuan Le,Hoang Sinh Le,Vy Anh Tran,이상화,Van-Dat Doan,주상우,Yasser Vasseghian 한국공업화학회 2022 Journal of Industrial and Engineering Chemistry Vol.115 No.-
The present study offers a novel recyclable Fe3O4/MnO2/ZIF-8 heterojunction photocatalyst for the degradationof reactive blue 19 (RB19) under visible light irradiation. The catalyst was facilely synthesized bydepositing Fe3O4/MnO2 nanocomposite onto the surface of ZIF-8 and characterized by field-emissionscanning electron microscopy, transmission electron microscopy, Fourier-transform infrared spectroscopy,X-ray diffraction, nitrogen adsorption–desorption isotherms and UV–vis spectroscopy. Morphology and structure characterization of the prepared photocatalyst indicated that polyhedralZIF-8 (ca. 500 nm) was coated by MnO2/Fe3O4 nanorods. The synergy effect of Fe3O4/MnO2/ZIF-8 compositeexhibited an excellent photocatalytic activity toward RB19 degradation of 99.5 % after 60 min of irradiationdue to high surface area and heterojunction formation. According to scavenger tests, thephotodegradation of RB19 dye over Fe3O4/MnO2/ZIF-8 was mainly contributed by OH and O2reactiveradicals. The kinetic study showed that the catalytic degradation of RB19 on Fe3O4/MnO2/ZIF-8 was betterdescribed by the first-order kinetic model. The new catalyst was easily recovered using an external magneticfield because of its magnetic properties. Besides, Fe3O4/MnO2/ZIF-8 showed high recyclability andstability, maintaining a high removal efficiency of 91.3 % even after ten repeated cycles. The overallresults indicated that the fabricated composite can be used as an efficient photocatalyst for treatingorganic dyes in wastewater.
High-Resolution Simulations for Vietnam - Methodology and Evaluation of Current Climate
Jack Katzfey,Kim Nguyen,John McGregor,Peter Hoffmann,Suppiah Ramasamy,Hiep Van Nguyen,Mai Van Khiem,Thang Van Nguyen,Kien Ba Truong,Thang Van Vu,Hien Thuan Nguyen,Tran Thuc,Doan Ha Phong,Bang Thanh Ng 한국기상학회 2016 Asia-Pacific Journal of Atmospheric Sciences Vol.52 No.2
To assist the government of Vietnam in its efforts to better understand the impacts of climate change and prioritise its adaptation measures, dynamically downscaled climate change projections were produced across Vietnam. Two Regional Climate Models (RCMs) were used: CSIRO’s variable-resolution Conformal-Cubic Atmospheric Model (CCAM) and the limited-area model Regional Climate Model system version 4.2 (RegCM4.2). First, global CCAM simulations were completed using bias- and variance-corrected sea surface temperatures as well as sea ice concentrations from six Coupled Model Intercomparison Project Phase 5 (CMIP5) global climate models. This approach is different from other downscaling approaches as it does not use any atmospheric fields from the GCMs. The global CCAM simulations were then further downscaled to 10 km using CCAM and to 20 km using RegCM4.2. Evaluations of temperature and precipitation for the current climate (1980-2000) were completed using station data as well as various gridded observational datasets. The RCMs were able to reproduce reasonably well most of the important characteristics of observed spatial patterns and annual cycles of temperature. Average and minimum temperatures were well simulated (biases generally less than 1oC), while maximum temperatures had biases of around 1oC. For precipitation, although the RCMs captured the annual cycle, RegCM4.2 was too dry in Oct.-Nov. (−60% bias), while CCAM was too wet in Dec.- Mar. (130% bias). Both models were too dry in summer and too wet in winter (especially in northern Vietnam). The ability of the ensemble simulations to capture current climate increases confidence in the simulations of future climate.
Van Noi Nguyen,Thi Dieu Cam Nguyen,Thanh Phuong Dao,Hung Thuan Tran,Dinh Bang Nguyen,안대희 한국공업화학회 2013 Journal of Industrial and Engineering Chemistry Vol.19 No.2
Organoclays were synthesized by exchanging inorganic cations between layers in Thanh Hoa bentonite using organic cations including benzylhexadecyldimethylammonium (BHDDM+), dimethyldioctadecylammonium (DMDOD+) and benzylstearyldimethylammonium (BSDM+). Inserting organic cations increases material interlayer distance significantly (from 15 A˚ to 40 A˚ ) and simultaneously enhances affinity of materials toward organic pollutants. The results show that adsorption capacity of organics on organoclays strongly depends on affinity between organic substances and ammonium cations rather than on interlayer distance of organoclays. This means that the sorption of organoclays for organic contaminants was significantly influenced by the nature of the surfactants added to the clay.
Tran Thi Kieu Ngan,Le Van Thuan,Nguyen Tien Hoang,Doan Van Dat,Vasseghian Yasser,Le Hoang Sinh 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.7
The present study provides an eco-friendly and economical way to recycle discarded cigarette butts (CBs). The raw CBs were treated with NaOH (CB-B) and integrated with chitosan (Cs), and further applied as an adsorbent for the removal of synthetic dyes. Two common cationic dyes of methylene blue (MB) and crystal violet (CV) and one anionic dye of reactive blue 19 (RB 19) were selected as model adsorbates. The study results revealed that CB-B showed a high adsorption ability toward cationic dyes, while the CB-B/Cs composite exhibited a stronger affinity for the anionic RB 19. The adsorption of all selected dyes onto CB-B and CB-B/Cs was a spontaneous exothermic process, conforming to the pseudo-first-order kinetic and Langmuir isotherm models. The maximum adsorption capacities for MB, CV and RB 19 at pH of 7, an adsorbent dosage of 4, and a temperature of 25 °C were 89.85, 82.41, and 304.49 mg/g, respectively. The primary adsorption mechanism was physical adsorption with the participation of electrostatic attraction. The CB-based adsorbents displayed high reusability, maintaining more than 75% after four consecutive cycles of reuse. This study demonstrates the promising application potential of CB-based adsorbents for treating synthetic dyes in wastewater. The conversion of CBs into a useful high-value material has special significance for environmental engineering.
Analysing Productivity in Vietnamese Seafood Processing Firms: A Control Function Approach
NGUYEN, Van,TRAN, Thuan Duc,MAI, Thanh Khac Korea Distribution Science Association 2021 The Journal of Asian Finance, Economics and Busine Vol.8 No.2
This study aims to estimate the production function and total factor productivity (TFP) of Vietnamese seafood processing firms. At the same time, the study analyses the impact of internal factors of firms and the quality of economic institutions on the TFP of the Vietnamese seafood processing industry. The study uses the Function Control (FC) approach in TFP estimation and the Feasible Generalized Least Squares (FGLS) regression model in the analysis of factors affecting TFP. The study was carried out on the census data of enterprises of the Vietnamese seafood processing industry collected by the Vietnamese General Statistics Office and Provincial Competitiveness Index data of Vietnam Chamber of Commerce and Industry in the period from 2013 to 2018. Estimated results from the models show that: i) Vietnamese seafood processing firms are, currently, mainly labor-intensive, the TFP contribution and output is only about 2.258. ii) Factors such as the firm's age, firm's size, and the firm's ownership affect TFP. In which, firms that have few numbers of years of operation, small and medium firms, and private firms have low TFP. iii) Institutional quality and the provincial business environment have a positive impact on the TFP of Vietnamese seafood processing firms in this period.
( Nguyen Van Tuyen ),( Tran Hung Thuan ),( Chu Xuan Quang ),( Nhat Minh Dang ) 한국공업화학회 2023 공업화학 Vol.34 No.5
The effect of temperature and influent alkalinity/ammonia (K/A) ratio on the start-up of the partial nitrification (PN) process for an activated sludge-based domestic wastewater treatment was studied. Two different sequence batch reactors (SBR) were operated at 26 °C and 32 °C. The relationship between temperature and the concentration of free ammonia (FA) and free acid nitrite (FNA) was investigated. A stable PN process was achieved in the 32 °C reactor when the influent ammonium concentration was lower than 150 mg-N/L. In contrast, the PN process in the 26 °C reactor had a higher nitrite accumulation rate (NAR) and ammonium removal efficiency (ARE) when the influent ammonia concentration was increased to more than 150 mg-N/L. Then three different ranges of the K/A ratio were applied to an SBR reactor. In the K/A range of 2.48~1.65, the SBR reactor achieved the highest NAR ratio (75.78%). This ratio helps to achieve the appropriate level of alkalinity to maintain a stable pH and provide a sufficient amount of inorganic carbon source for the activity of microorganisms. At the same time, FA and FNA values also reached the threshold to inhibit nitrite-oxidizing bacteria (NOB) without a significant effect on ammonia-oxidizing bacteria (AOB). Results showed that the control of temperature and K/A ratio during the start-up period may be important in establishing a stable and steady PN process for the treatment of domestic wastewater.