KMITL

Permanent URI for this communityhttps://dspace.kmitl.ac.th/handle/123456789/1

Browse

Search Results

Now showing 1 - 10 of 11

Some of the metrics are blocked by your
consent settings
Synergistic torrefaction and co-combustion of rice husk and spent coffee grounds: Thermo-kinetics, ash morphology, and waste-to-energy implications
(2026-09-01)
Pambudi, Suluh
;
Jongyingcharoen, Jiraporn Sripinyowanich
;
Saechua, Wanphut
Combining silica-rich agricultural residues such as rice husk (RH) with energy-dense food-processing waste like torrefied spent coffee grounds (TSCG) offers a circular strategy to exploit the complementary advantages of each biomass while improving fuel performance and combustion reliability. Therefore, the objective of this study is to systematically investigate the co-combustion behavior, kinetic performance, and ash morphology of RH and TSCG blends using thermogravimetric analysis across multiple blend ratios and heating rates. Optimal co-combustion characteristics were observed for blends containing 40–60% RH, demonstrated by comprehensive combustion index values up to 6.02 × 10–6%2 min–2 °C–3 and flammability indices exceeding 0.72 × 10–4% min–1 °C–2. Furthermore, these blends exhibited low activation energies during dehydration (150–161 kJ mol⁻¹), devolatilization (143–175 kJ mol⁻¹), and char oxidation (89–134 kJ mol⁻¹). Notably, these blends exhibit high carbon conversion efficiency, leading to a relatively low residual ash content (10.25–14.36%). Synergistic effects, characterized by experimental mass loss exceeding theoretical predictions by up to 2%, were confirmed above 300 °C. This synergistic behavior is attributed to the interaction between oxygenated volatiles released from RH and the catalytic effects of alkali and alkaline earth metals present in TSCG, along with the stabilizing role of silica in mitigating ash-related issues. Additionally, increasing the proportion of TSCG promoted earlier ignition (T<inf>i</inf> reduced to 213 °C) but prolonged the char combustion stage, resulting in higher burnout temperatures of up to 678 °C. Morphological and elemental ash analysis revealed that moderate Si content in 40–60% RH blends contributed to thermal stability while suppressing alkali-induced slag formation. Collectively, these results demonstrate that co-combustion of RH with TSCG significantly enhances combustion reactivity, promotes kinetic synergy, and improves thermal stability. These findings highlight the potential of RH–TSCG blends as efficient and environmentally sustainable fuels for bioenergy applications by utilizing readily available local biomass residues.
Some of the metrics are blocked by your
consent settings
Adsorption of silver, thorium and nickel ions from aqueous solution onto rice husk
(2021-10-01)
Zafar, Shagufta
;
Khan, Muhammad Imran
;
Shanableh, Abdallah
;
Ahmad, Saleem
;
Manzoor, Suryyia
In this article, adsorption of metal ions such as silver (Ag(I)), thorium (Th(IV)) and nickel (Ni(II)) from aqueous solution onto rice husk (RH) was performed at room temperature. Adsorption of these metal ions (silver, thorium, and nickel) onto RH was demonstrated by using Fourier trans-form infrared spectroscopy and energy-dispersive X-ray. Morphology of RH was investigated before and after adsorption of these metal ions onto it by using scanning electron microscopy. The effect of different operational parameters (contact time, initial concentration of metal ion solution, weight of RH, pH, and temperature) on the percentage removal of these metal ions was explored in detail and compared. Experimental data for adsorption of these metal ions onto RH was sub-jected to Langmuir and Freundlich isotherm models. Results showed that adsorption of silver and thorium fitted well to Langmuir isotherm model (R2 > 0.99) whereas adsorption of Ni(II) fitted well to Freundlich isotherm model (R2 > 0.99). Adsorption kinetics study demonstrated that adsorp-tion of these metal ions onto RH from aqueous solution fitted well to pseudo-second-order model. Adsorption thermodynamics investigation represented that adsorption of these metal ions onto RH was endothermic process. The values of Gibb’s free energy were –6.53 to –9.17 kJ/mol for Ag(I), –1.11 to –3.57 kJ/mol for Th(IV) and –0.89 to –1.40 kJ/mol for Ni(II). The negative values of Gibb’s free energy for these metal ions suggested that the adsorption process was spontaneous in nature. The regeneration of RH and recovery of these metal ions were also studied.
Some of the metrics are blocked by your
consent settings
Kinetic, equilibrium, and thermodynamic studies for adsorptive removal of cobalt ions by rice husk from aqueous solution
(2020-11-01)
Zafar, Shagufta
;
Khan, Muhammad Imran
;
Rehman, Hafeez Ur
;
Fernandez-Garcia, Javier
;
Shahida, Shabnam
Herein, batch adsorptive removal of cobalt ions (Co(II)) from aqueous solution was studied at room temperature. Adsorption of cobalt ions onto rice husk (RH) was confirmed by utilizing Fourier transform infrared, scanning electron microscopy, and energy diffraction energy-dispersive X-ray analysis. The effect of contact time, mass of RH, initial concentration of cobalt ion solution, tem-perature, and pH on the percentage discharge of Co(II) was revealed. The nonlinear models such as pseudo-first-order model, pseudo-second-order model, intraparticle diffusion model, and Elovich model were utilized to study kinetics for adsorptive removal of cobalt ions (Co(II)) from aqueous solution. Results showed that experimental data fitted well to nonlinear pseudo-second-order kinetic model. Nonlinear isotherms such as Langmuir, Freundlich, and Dubinin–Radushkevivh (D–R) were used to reveal experimental data of cobalt ion adsorption onto RH. Results represented that experimental data fitted well to nonlinear isotherms. Adsorption thermodynamic study showed that adsorption of Co(II) onto RH was an endothermic and spontaneous process. Moreover, desorp-tion of cobalt ions was also revealed. Therefore, RH could be utilized as a good adsorbent for the removal of Co(II) from aqueous solution at room temperature.
Some of the metrics are blocked by your
consent settings
Prediction of higher heating value, lower heating value and ash content of rice husk using FT-NIR spectroscopy
(2018-09-30)
Nakawajana, Natrapee
;
Posom, Jetsada
;
Paeoui, Jaruwat
Rice husk is the significant waste residue to be used as renewable energy. The growth of the use on rice husk for generating electricity lead to the verification of its properties. This research aimed to predict higher heating value (HHV), lower heating value (LHV), and ash content (A) of rice husk using Fourier Transform near infrared (FT-NIR) spectroscopy. Rice husk samples used in this experiment were collected from variable areas in Thailand in order to improve the model and get the robust model. The models were built using partial least squares (PLS) regression and validated by unknown sample collected from different area to calibration set. The prediction of HHV, LHV and A were represented the root mean square error of cross validation (RMSECV) of 119 J/g, 119 J/g, and 0.859%wb, respectively. The calibration model can predict the unknown sample successfully with the relative standard error of prediction (RSEP) of 1.104 %, 1.159 %, and, 5.975 %, which implied good performance of NIR model for future prediction. The results suggested that HHV, LHV, and A models should be able to assess the properties of rice husk samples and showed that NIR was reliable and suitable method for combustion system to screening material.
Some of the metrics are blocked by your
consent settings
Adsorption of free fatty acid from crude palm oil on magnesium silicate derived from rice husk
(2011-08-01)
Clowutimon, Weerawat
;
Kitchaiya, Prakob
;
Assawasaengrat, Pornsawan
Magnesium silicate with various silica and magnesium oxide ratios (SiO<inf>2</inf>/MgO ratios) was used as the adsorbent for a study of adsorption of free fatty acid (FFA) in crude palm oil (CPO). Magnesium silicate was prepared from magnesium nitrate or magnesium sulfate solution precipitated with a solution of sodium silicate derived from rice husk. SiO<inf>2</inf>/MgO ratios of the magnesium silicate synthesized from magnesium nitrate and magnesium sulfate were 3.93, 3.75, 2.74, 2.40, 1.99 and 3.96, 3.61, 3.51, 2.91, 2.69, respectively. FFA adsorption on the magnesium silicate was carried out by adding 1 gram of the adsorbent to 50 grams of CPO and shaking for 1 hour at 50°C. It was found that SiO<inf>2</inf>/MgO prepared from magnesium nitrate ratio of 1.99 had the highest adsorption capacities of 185 mg of FFA per gram of adsorbent. In addition, increasing of SiO<inf>2</inf>/MgO ratios of magnesium silicate was found to reduce the adsorption capacities due to decreasing of FFA chemisorption. The effect of dosage amount to equilibrium adsorption capacities were carried out by adding different amount of magnesium silicate (SiO<inf>2</inf>/MgO ratio of 1.99) to 50 grams of CPO. The result showed that efficiency decreased when dosage increased. The Fruendlich and Langmuir isotherm were applied to describe this absorption system. The values of maximum sorption capacity (Q0) and Langmuir's sorption affinity (b) in the Langmuir equation obtained by linear-regression were minus values which were physically meaningless. Thus, FFA adsorption on magnesium silicate was both physisorption and chemisorption and well represented by the Fruenlich isotherm.
Some of the metrics are blocked by your
consent settings
Combustion of rice husk in a fluidized bed combustor with wavy-surfaced chambers
(2009-01-01)
Kaewkohkiat, Y.
;
Eiamsa-Ard, S.
;
Wongcharee, K.
;
Thungsotanon, D.
;
Promvonge, P.
The paper deals with an experimental investigation on effects of percent excess airs (EA = 15%, 30%, 45%, 60%, and 75%) on axial/radial temperature distributions, gas emissions and combustion efficiency in a fluidized bed combustor (FBC) with wavy surfaces using rice husk as the fuels. The combustion chamber shape is cylindrical with 200 mm in diameter (D) and 2400 mm in height (H). The top part of the chamber is designed and constructed to be wavy surface walls. In constructing the wavy surface bed at the top chamber, five modules of converging-diverging nozzles are inserted into the bed at which each module has a throat diameter of 100 mm and height of 200 mm. In the experiments, the axial/radial temperature distributions inside the combustor are measured for each percent excess air used while the feeding rate of rice husk is kept constant at 95 kg/hr. From experimental results, the emissions of flue gases are found to be CO = 308 ppm and NO<inf>x</inf> = 298 ppm, at EA = 75%. At all percent excess airs (EA) the axial/radial temperature distributions in the chamber are nearly uniform.
Some of the metrics are blocked by your
consent settings
Combustion behavior in a dual-staging vortex rice husk combustor with snail entry
(2008-11-01)
Eiamsa-ard, S.
;
Kaewkohkiat, Y.
;
Thianpong, C.
;
Promvonge, P.
The combustion characteristics of rice husk fuel in a dual-staging vortex-combustor (DSVC) are experimentally investigated. In the present work, the vortex flow is created by using a snail entrance mounted at the bottom of the combustor. The temperature distributions at selected locations inside the combustor, the flue gas emissions (CO, CO<inf>2</inf>, O<inf>2</inf>, NO<inf>x</inf>), and the combustion/thermal efficiency are monitored. Measurements are made at a constant rice husk feed rate of 0.25 kg/min with various excess airs (37%, 56%, 74% and 92%) and different secondary air injection fractions (λ = 0.0, 0.15 and 0.2), respectively. The combustion chamber is 1800 mm high and 300 mm in diameter (D) with a centered exhausted pipe while the middle chamber of the combustor is set to 0.5D. The smaller section at the middle chamber is introduced to split the chamber to be dual-staging chamber where a large central toroidal recirculation zone induced by swirl flow through the small section is generated in the top chamber. The experimental results reveal that the highest temperature inside the combustor is about 1000 °C whereas both the thermal and the combustion efficiency are 41.6% and 99.8% for 74% excess air without the secondary air injection (λ = 0.0). In addition, the emissions are CO<inf>2</inf> = 8.1%, O<inf>2</inf> = 9.3%, CO = 352 ppm, NO<inf>x</inf> = 294 ppm and small amount of fly ash. Therefore, the DSVC shows an excellent performance, low emissions, high stabilization and ease of operation in firing the rice husk. © 2008 Elsevier Ltd. All rights reserved.
Some of the metrics are blocked by your
consent settings
Experimental investigation of combustion characteristics in a multi-staging vortex combustor firing rice husk
(2008-02-01)
Eiamsa-ard, Smith
;
Kaewkohkiat, Yingyong
;
Lelaphatikul, Wisit
;
Thianpong, Chinaruk
;
Promvonge, Pongjet
The paper described the combustion characteristics in a multi-staging vortex combustor by using rice husk as fuel. Effects of the operating conditions namely: equivalence ratio (Φ = 0.8, 1.0 and 1.2) and secondary air ratio (λ = 0.0, 0.15 and 0.25) on combustion characteristics (temperature distribution, fly ash and gas emission) were experimentally studied. In the experiments, the conventional vortex combustor consisted of two straight concentric cylindrical pipes, combustion chamber (outer chamber) and exhaust pipe (inner chamber). The variable size of middle section of the combustor was designed to be adjustable from 1.0D (conventional vortex combustor), to 0.75D and 0.5D as desired. The changes of the middle chamber size lead to multi-staging vortex inside the combustor. In the experiments, the rice husk was fed into the combustor at constant mass flow rate of 0.3 kg/min. Test results revealed that the mean temperature distribution for the multi-staging vortex combustor with middle chamber size of 0.5D was higher than those of 0.75D and 1.0D. The experimental results showed the maximum temperature of about 1176 °C in the vortex chamber with the middle chamber of 0.5D at equivalence ratio, Φ = 0.8 and no secondary air injection, λ = 0.0. Measurements of gas emissions from cyclone collector consisted of O<inf>2</inf> = 2.5%, CO<inf>2</inf> = 17.3%, and CO = 270 ppm, respectively. © 2007 Elsevier Ltd. All rights reserved.
Some of the metrics are blocked by your
consent settings
Semi-micro preparation and characterization of mesoporous silica microspheres from rice husk sodium silicate using a non-ionic surfactant as a template: Application in normal phase HPLC columns
(2007-07-01)
Tungkananurak, Kanita
;
Kerdsiri, Sirinlux
;
Jadsadapattarakul, Damrongsak
;
Burns, Duncan Thorburn
A simple and low-cost process has been developed for the production of mesoporous silica microspheres using a non-ionic surfactant as a template in an aqueous acidic sodium silicate solution prepared from rice husk. The influences of synthesis parameters such as the sodium silicate concentration, hydrochloric acid concentration, temperature and aging time on the morphology and on particle size range are described. The product's physical and normal phase chromatographic properties are reported. © 2007 Springer-Verlag.
Some of the metrics are blocked by your
consent settings
Semi-micro preparation and characterization of bonded phase ODS-silica prepared from rice husk silica
(2006-04-01)
Burns, Duncan Thorburn
;
Tungkananurak, Kanita
;
Jadsadapattarakul, Damrongsak
Bonded phase ODS-silica has been prepared using purified silica prepared from rice husk by burning, reflux with sodium hydroxide solution and precipitation as a gel. The gel was spray dried, further purified by washing with concentrated hydrochloric acid then distilled water prior to vacuum drying and silanization and end-capping. The product's physical and chromatographic properties are reported. © Springer-Verlag 2006.

KMITL

Browse

Filters

Settings

Sort By

Results per page

Search Results