Browsing by Author "Piyaporn Waranusantigul"

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    A Study of the Optimal Conditions for Extracting and Precipitating Silica from Rice Husk Using the Hydrothermal Method in a Base Medium
    (Research and Development Institute Suan Dusit University, 2024) Orapin Komutiban; Jantharat Wutisatwongkul; Sorasutee Buapool; Khwunjit Itsarasook; Piyanuch Prompamorn; Jittarawadee Tanghiranra; Piyaporn Waranusantigul; J. Wutisatwongkul; Faculty of Science and Technology, Suan Dusit University, Bangkok, 10700, Thailand; email: jantharat_wut@dusit.ac.th
    This research investigated the extraction and precipitation methods of silica from rice husk using hydrothermal treatment under basic conditions. It was observed that by subjecting raw rice husk and black rice husk ash to burnt at a temperature of 700¡C for 6 hr raw rice husk yielded 10.68%, while black rice husk yielded 85.40%. The optimal condition for extracting silica is 1 molar of sodium hydroxide at a temperature of 100¡C for 6 hr. Silica extracted from raw materials that have undergone acid pretreatment yields a higher quantity compared to silica from untreated raw materials. However, the raw rice husk, burnt raw rice husk, black rice husk ash and burnt black rice husk ash have silica % of 16.20, 77.60, 63.10 and 89.0, respectively. When the extracted silica was analyzed for its physical characteristics using an inverted microscope, it was observed that silica subjected to acid pretreatment exhibits uniformly sized particles. The examination of particle size using the extraction method revealed that the silica particles were smaller than 53 _m and when all extracted silica was analyzed for functional groups using the FT-IR technique, the siloxane group (Si-O-Si) was found in the wavenumber range of 1,090-801 cm-_. Additionally, the hydroxyl group (-OH) was observed at the wavenumber of 3,400 cm-_. After conducting BrunauerÐEmmettÐTeller Analysis (BET analysis) on silica obtained from burnt rice husk and burnt black rice husk ash, both untreated and treated with HCl, it was found that the pore diameter of the extracted silica ranged from 8.14 to 19.15 nm. This suggests that the silica possesses mesoporous characteristics. Furthermore, the acid-leached silica exhibited a decrease in particle size and an increase in surface area. Specifically, the silica derived from burnt rice husk and treated with HCl demonstrated particle size and surface area values that closely resembled those of commercial-grade silica. When studying the effectiveness of silica in adsorbing methylene blue, the findings showed that the extracted silica demonstrates better adsorption capability for methy lene blue compared to commercial silica. The adsorption values ranged from 1302.49 to 1706.35 mg MB/g, representing 65.78-86.17%. From the investigation of the isotherm for methylene blue adsorption with the extracted silica, it is evident that the adsorption conforms to Freundlich model, indicating a multilayer adsorption behaviour. The method of extracting and precipitating silica through hydrothermal treatment under basic conditions proves to be an effective approach for preparing micro-sized silica particles. © 2024, Research and Development Institute Suan Dusit University. All rights reserved.
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    A Study of the Optimal Conditions for Extracting and Precipitating Silica from Rice Husk Using the Hydrothermal Method in a Base Medium
    (Graphicsite, 2024-04-30) Orapin Komutiban; Jantharat Wutisatwongkul; Sorasutee Buapool; Khwunjit Itsarasook; Piyanuch Prompamorn; Jittarawadee Tanghiranra; Piyaporn Waranusantigul
    This research investigated the extraction and precipitation methods of silica from rice husk using hydrothermal treatment under basic conditions. It was observed that by subjecting raw rice husk and black rice husk ash to burnt at a temperature of 700°C for 6 hr raw rice husk yielded 10.68%, while black rice husk yielded 85.40%. The optimal condition for extracting silica is 1 molar of sodium hydroxide at a temperature of 100°C for 6 hr. Silica extracted from raw materials that have undergone acid pretreatment yields a higher quantity compared to silica from untreated raw materials. However, the raw rice husk, burnt raw rice husk, black rice husk ash and burnt black rice husk ash have silica % of 16.20, 77.60, 63.10 and 89.0, respectively. When the extracted silica was analyzed for its physical characteristics using an inverted microscope, it was observed that silica subjected to acid pretreatment exhibits uniformly sized particles. The examination of particle size using the extraction method revealed that the silica particles were smaller than 53 μm and when all extracted silica was analyzed for functional groups using the FT-IR technique, the siloxane group (Si-O-Si) was found in the wavenumber range of 1,090-801 cm-¹. Additionally, the hydroxyl group (-OH) was observed at the wavenumber of 3,400 cm-¹. After conducting Brunauer–Emmett–Teller Analysis (BET analysis) on silica obtained from burnt rice husk and burnt black rice husk ash, both untreated and treated with HCl, it was found that the pore diameter of the extracted silica ranged from 8.14 to 19.15 nm. This suggests that the silica possesses mesoporous characteristics. Furthermore, the acid-leached silica exhibited a decrease in particle size and an increase in surface area. Specifically, the silica derived from burnt rice husk and treated with HCl demonstrated particle size and surface area values that closely resembled those of commercial-grade silica. When studying the effectiveness of silica in adsorbing methylene blue, the findings showed that the extracted silica demonstrates better adsorption capability for methy lene blue compared to commercial silica. The adsorption values ranged from 1302.49 to 1706.35 mg MB/g, representing 65.78-86.17%. From the investigation of the isotherm for methylene blue adsorption with the extracted silica, it is evident that the adsorption conforms to Freundlich model, indicating a multilayer adsorption behaviour. The method of extracting and precipitating silica through hydrothermal treatment under basic conditions proves to be an effective approach for preparing micro-sized silica particles.
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    Isolation and characterization of lead-tolerant Ochrobactrum intermedium and its role in enhancing lead accumulation by Eucalyptus camaldulensis
    (Elsevier Ltd, 2011) Piyaporn Waranusantigul; Hung Lee; Maleeya Kruatrachue; Prayad Pokethitiyook; Choowong Auesukaree; C. Auesukaree; Department of Biology, Faculty of Science, Mahidol University, Bangkok 10400, Rama VI Road, Thailand; email: sccar@mahidol.ac.th
    In this study, the potential of rhizospheric bacteria in promoting the growth and Pb accumulation by the woody plant Eucalyptus camaldulensis under hydroponic conditions was investigated for the first time. Three Pb-tolerant bacteria were isolated from the rhizosphere of E. camaldulensis grown in Pb-contaminated soils in the Bo Ngam Pb mine, Thailand. Based on analysis of partial 16S rRNA gene sequence, the three isolates were identified as Microbacterium paraoxydans BN-2, Ochrobactrum intermedium BN-3, and Bacillus fusiformis BN-4. Among these strains, O. intermedium BN-3 showed the highest tolerance to not only Pb but also Cd and Zn. After growth in the presence of Pb, the membranes of O. intermedium BN-3 cells exhibited an increase in unsaturated fatty acid levels but a decrease in fluidity. In hydroponic studies, inoculation of O. intermedium BN-3 significantly increased the biomass and Pb accumulation by E. camaldulensis compared to the uninoculated control. The results suggested the role of the natural rhizospheric bacteria localized to the root surface of E. camaldulensis in promoting Pb accumulation and plant growth. Our results indicate that O. intermedium BN-3 and other indigenous rhizospheric bacteria have the potential to improve the efficiency of phytoremediation of Pb-contaminated sites. © 2011 Elsevier Ltd.