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Synthesis of durian shell activated carbon by KOH activation using response surface methodology: characterization and optimization of process parameters
(2024-06-01)
Roddaeng, Songkiat
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Promvonge, Pongjet
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Anuwattana, Rewadee
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Vongpanit, Pleuk
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Suriyachai, Nopparat
The use of agricultural waste as a raw material for activated carbon production has the potential to offer a sustainable, low-cost, and environmentally friendly alternative to traditional methods. In this research, activated carbon was prepared from durian shell agricultural waste. Chemical activation with potassium hydroxide (KOH) via microwave heating was used in the process. The response surface methodology (RSM) technique was conducted to optimize the activation parameters, where the influences of various parameters, such as microwave power, carbon to potassium hydroxide (C/KOH) ratio, and activation times, on prepared durian shell char (PDSC) were investigated. The result from RSM model showed that the optimum values of each parameter were 691.3 W, 2.58, and 31.4 min for microwave power, C/KOH ratio, and activation times, respectively; these parameters corresponded to values of 239 mg/g and 965 mg/g for the methylene blue number (MBN) and iodine number (IDN), respectively. The properties of the obtained durian shell activated carbon (DSAC) were characterized using Brunauer–Emmett–Teller (BET), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR). The results revealed a pore volume of 0.3779 cm3/g with an amorphous structure, while BET surface area and mesopore surface area were identified to be 592.0 m2/g and 389.1 m2/g, respectively. The FTIR results showed the changes in functional groups after activation. Graphical abstract: (Figure presented.)
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Investigation of heat and moisture transport in bananas during microwave heating process
(2019-08-01)
Thuto, Wisara
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Banjong, Kittichai
The numerical method was used to investigate heat and moisture transport during dehydration of bananas from microwave heating. COMSOL multi-physics software was employed to perform the simulation task. A banana is defined as a porous medium. It has constituents of water, vapor, air as the liquid phase and a solid porous matrix. The numerical results of this study were validated with experimental data. The profiles of moisture, vapor and pressure are discussed in this study. Moreover, the effects of the ripening stages of the banana are examined. A higher heat flux was observed from the beginning period along with the increasing time steps until 50 s. Heat generation decreased during 50 s to 60 s, coinciding with a small rise in temperature, but the temperature gradient remained constant. The temperature distribution of both unripe and ripe banana samples was non-uniform. At the center of the banana, the temperature increased rapidly and reached its highest temperature with the negative temperature gradient toward the boundary surface. More heat generation was observed around the center region of the banana. This was due to higher moisture in comparison with the boundary surface. Heat and moisture were transported from the center of the banana to its surface. The water convective flux peaked around 11 mm from the center. The vapor pressure peaked at the center for all cases. Less heat generation within unripe bananas was observed due to the lower moisture content.
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Design, fabrication and operation of continuous microwave biomass carbonization system
(2014-06-01)
Payakkawan, Poomyos
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Areejit, Suwilai
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Sooraksa, Pitikhate
This paper presents a new design and the fabrication of biomass carbonization system using microwave heating. The heating system employs multi-feed microwave generators with 8.5kW maximum power and 2.458GHz frequency for uniform heating distribution in a 0.847m3 cylindrical low cement castable reactor. The experiment entails the carbonization of 58,800kg of coconut shell for 7 days. Afterward, the charcoal and wood vinegar yields are analyzed; meanwhile, uncondensed gases are treated to fuel the engine-generator system. The results show that the proposed approach greatly saves the production time of charcoal yields and allows ease of temperature control. © 2013 Elsevier Ltd.
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Microwave ablation system design to study the effects of coaxial antenna on in-vitro animal tissue
(2014-01-01)
Chaichanyut, M.
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Lertprasert, P.
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Tungjitkusolmun, S.
This paper presents a novel low cost microwave ablation system design to study the effects of coaxial antenna on In Vitro animal tissues. The system utilizes a high-voltage power supply so that the magnetron can generate a microwave field continuously, and its output power can be adjusted from 10 - 80 W at frequency of 2.45GHz. We control output microwave power level by using control the magnetron power supply, which it is an important part of a microwave heating system. Power control of the magnetron’s power supply is desired for microwave heating to enhance performance and to provide system flexibility. The high frequency switching technique in the power supply control is costly and complicated. In another way, pulsing the output power of the magnetron can be simply realized with TRIAC, but in that case the magnetron does not operate continuously. The proposed circuit is a simple one with TRIAC. The power control is achieved by controlling the triggering events at appropriate phase angle of the household 220V. Experimental protocol was composed by a radiation system and a thermometry system. Coaxial antenna works at 2.45 GHz, power apply during experiments was 10W×8min; 20W×4min; 40W×2min and 80W×1min. Thermal sensors were placed next to the antenna at 1mm., a large number of experiments on porcine liver are carried out, the temperature distribution within the liver are measured and illustrated, for cases of different injected microwave power and ablation time. In addition, the ablation areas in cases of different input microwave powers are measured also. All these results indicate the potential validity of this system on medical treatment of liver cancer of human body.
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Novel microwave carbonization system for coconut shells
(2013-10-07)
Payakkawan, Poomyos
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Areejit, Suwilai
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Sooraksa, Pitikhate
This paper presented a novel heating technique of biomass carbonization system using microwave radiation. The heating system employs multi-feed microwave generators for uniform heating distribution without stirrer mechanism in a 0.847 m3 cylindrical low cement castable reactor. The experiment entailed the carbonization of 3,500 kg of coconut shell at 450°C for 10 hr. Afterward, the charcoal and wood vinegar yields were analyzed; meanwhile, uncondensed gases were treated to fuel the engine-generator system. The results show that the proposed approach greatly saves the production time of charcoal yields and allows ease of control. © (2013) Trans Tech Publications, Switzerland.
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A continuous fluidized bed microwave paddy drying system using applicators with perpendicular slots on a concentric cylindrical cavity
(2011-01-01)
Sangdao, Chokchai
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Songsermpong, Sirichai
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Krairiksh, Monai
This article presents a continuous fluidized bed microwave drying system that provided a higher drying capacity than that provided by comparable conventional hot air drying systems. Its applicator consists of perpendicular slots over a concentric cylindrical cavity that is excited by perpendicular waveguides. The paddy to be dried was dropped vertically into the center of the applicator while hot air at 60° C, heated by magnetron ventilation, was injected from the opposite direction. Statistical data on the temperature distribution of the paddy, which scattered over the whole volume of the applicator, were collected and analyzed together with the probability of its orientation, position, and density. A suitable system was proposed, constructed, and tested. It provided good quality dried paddy, similar to that from a fluidized bed drying system. The system's maximum leakage power of 4.8 mW/cm2 was well within the safety standard. With only 5.2 kJ of energy consumption, this system reduced the moisture content of a large quantity of paddy from 24 to 14% (wb) with a capacity of 3.1 kg/h. The energy cost for drying was US$47.7/ton. © 2011 Taylor & Francis Group, LLC.

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