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Overview of Coffee Waste and Utilization for Biomass Energy Production in Vietnam
Thriveni, Thenepalli,Kim, Minsuk,Whan, Ahn Ji The Korean Society for Energy 2017 에너지공학 Vol.26 No.1
In this paper, the carbon resources recycling of the overview of coffee waste generation in Vietnam. Since few years, there has been a significant research studies was done in the areas of coffee waste generation areas and also waste water generation from coffee production. The coffee residue (solid) and waste water (liquid) both are caused the underground water contamination and also soil contamination. These residues contain high organic matter and acid content leads to the severe threat to environment. In second stage of coffee production process, the major solid residue was generated. Various solid residues such as spent coffee grounds, defective coffee beans and coffee husks) pose several environmental concerns and specific problems associated with each type of residue. Due to the unlimited usage of coffee, the waste generation is high. At the same time, some researchers have been investigated the spent coffee wastes are the valuable sources for various valuable compounds. Biodiesel or biomass productions from coffee waste residues are the best available utilization method for preventing the landfill problems of coffee waste residues.
Impacts of Climate Change on Water Crisis and Formation of Green Algal Blooms in Vietnam
Thriveni, Thenepalli,Lee, Namju,Nam, Gnu,Whan, Ahn Ji The Korean Society for Energy 2017 에너지공학 Vol.26 No.1
Global warming affects water supply and water resources throughout the world. In many countries, climate change affects significantly on the fresh water resources. Vietnam is exposed mainly, to landslides and floods triggered by tropical storms and monsoon rains, although storm surge, whirlwind, river bank and coastal line erosion, hail rain. In addition to the prevalent drought, there are many major water challenges, including water availability, stress, scarcity and accessibility, because of poor resource management. Fast growth of urbanization, industrialization and population growth, agricultural activities and climate change cause heavy pressure on water quality. Both domestic and industrial wastewater, as well as storm water shares the same drainage. The common facilities for wastewater treatment are not available. Therefore, wastewater is treated only superficially and then discharged directly into rivers and lakes causing serious pollution of surface water environment. In this paper, we reported the severe water crisis and massive green algal blooms formation in Vietnam rivers and lakes. This is the biggest evidence of climate change variations in Vietnam.
Factors Affecting the Crystal Growth of Scalenohedral Calcite by a Carbonation Process
Thriveni, Thenepalli,Um, Namil,Nam, Seong-Young,Ahn, Young Jun,Han, Choon,Ahn, Ji Whan The Korean Ceramic Society 2014 한국세라믹학회지 Vol.51 No.2
In the present work, we report a novel microstructure of scalenohedral calcite synthesized without any additives by a simple and ecofriendly carbonation process carried out in a liquid-gas system as well as the effects of experimental conditions on the crystal growth of the scalenohedral calcite phase. Various process parameters, pH, temperature, $Ca(OH)_2$ concentration, $CO_2$ flow rates, and the total volume concentration, were investigated to enhance the sensitivity of the process. The highest average length of the scalenohedral calcite was obtained at pH 6.0, temperature of $45^{\circ}C$, $Ca(OH)_2$ concentration of 0.2M, $CO_2$ flow rate of 80mL/min, and total volume of 1L. The synthesized calcite was characterized by XRD, SEM, and FTIR to identify the phases and surface morphology.
Thriveni, Thenepalli,Ahn, Ji Whan,Ramakrishna, Chilakala,Ahn, Young Jun,Han, Choon 한국물리학회 2016 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol. No.
<P>Nano calcium carbonate particles have a wide range of industrial applications due to their beneficial properties such as high porosity and high surface area to volume ratio and due to their strengthening the mechanical properties of plastics and paper. Consequently, significant research has been done to deliver a new approach for the synthesis of precipitated nano calcium carbonate by using a carbonation process through a closed loop reactor. Both the experimental and the instrumental parameters, i.e. the CO2 flow rate, the concentration of the starting materials (Ca(OH)(2) and CaO), the pH, the orifice diameter, etc., were investigated. The carbonation efficiency was increased due to the diffusion process involved in the loop reactor. The particle size was affected by the CO2 flow rate, reaction time, and orifice diameter. Finally, precipitated nano calcite calcium carbonate (50 to 100 nm) was synthesized by optimizing all the experimental and the instrumental parameters. The synthesized precipitated nano calcium carbonate was characterized by using scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FTIR) spectroscopy. This study has proved that the carbonation efficiency can be enhanced for a short time by using a loop reactor and that the carbonation process was more energy efficient and cost effective than other conventional methods.</P>
Thriveni Thenepalli,Ahn Young Jun,한춘,Chilakala Ramakrishna,안지환 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.6
A wide variety of fillers are currently used in more than twenty types of polymer resins, although four of them alone (polypropylene, polyamides, thermoplastic polyesters, and polyvinyl chloride) account for 90% of the market of mineral fillers in plastics. Polypropylene (PP) and PVC dominate the market for calcium carbonate. PP is a versatile reinforcement material that can meet engineering and structural specifications and is widely used for automotive components, home appliances, and industrial applications. Talc, mica, clay, kaolin, wollastonite, calcium carbonates, feldspar, aluminum hydroxide, glass fibers, and natural fibers are commonly used in fillers. Among these, calcium carbonate (both natural and synthetic) is the most abundant and affords the possibility of improved surface finishing, control over the manufacture of products, and increased electric resistance and impact resistance. Meeting the global challenge to reduce the weight of vehicles by using plastics is a significant issue. The current the global plastic and automobile industry cannot survive without fillers, additives, and reinforcements. Polypropylene is a major component of the modern plastic industry, and currently is used in dashboards, wheel covers, and some engine parts in automobiles. This article reports that the use of calcium carbonate fillers with polypropylene is the best choice to enhance the mechanical properties of plastic parts used in automobiles.