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    A novel colorimetric sensor based on modified mesoporous silica nanoparticles for rapid on-site detection of nitrite
    (2020-12-01)
    Taweekarn, Tarawee
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    Wongniramaikul, Worawit
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    Limsakul, Wadcharawadee
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    Sriprom, Wilasinee
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    A novel colorimetric sheet based on Griess reagent–doped mesoporous silica nanoparticles was developed for nitrite detection. Griess reagent was adsorbed on long–range ordered hexagonal mesoporous silica nanoparticles and developed ink–bottle pores with some disorder. When the modified nanoparticles were bound using starch to fabricate a thin (~ 313 μm) colorimetric sheet, spherical particles with a rougher surface and some distortion of their mesoporosity were observed. The sheet was used in conjunction with digital image colorimetry (DIC) and provides a wide linear range of 0.05 to 2.50 mg L<sup>−1</sup> with a low detection limit (15.0 μg L<sup>−1</sup>–NO<inf>2</inf><sup>−</sup>, equal to 4.5 μg L<sup>−1</sup> NO<inf>2</inf><sup>−</sup>–N), good inter-day precision (1.93%RSD), and excellent precision (2.67% relative error). The colorimetric sensors produced from the sheet costs only 0.04 USD each, while the DIC uses a standard smartphone for photographic detection. The method developed offers an easier and cheaper means of conducting rapid on-site determination of nitrite in water with reliable quantitative results. [Figure not available: see fulltext.]
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    Effective recovery of phosphate from wastewater using biodegradable calcium-rich shell wastes composite macroporous cryogel
    (2024-06-20)
    Kaewnoo, Satabodee
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    Wongniramaikul, Worawit
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    Boonkanon, Chanita
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    Taweekarn, Tarawee
    ;
    Kleangklao, Bussakorn
    The recovery of phosphorus from wastewater holds promise as a sustainable source of organic phosphorus for agricultural use while aiding in meeting legislative discharge limits for phosphorus to control and mitigate eutrophication. This study introduces a novel approach in which calcium-rich calcined oyster shell (Ca–COS) is immobilized on a starch-based monolithic cryogel, resulting in a green tablet (Cry–Ca–COS) capable of efficiently recovering phosphate from water through chemisorption on the material surface and precipitation in the liquid phase. The formed tablet prevents sorbent loss post-adsorption, facilitating reusability. Under optimal conditions (i.e., three 0.83 cm thick Cry–Ca–COS tablets, an initial phosphate concentration of 12 mg L<sup>−1</sup> in 1 L without pH adjustment (pH 6.3), and a contact time of 60 minutes), a phosphate removal efficiency of 83.11% ± 0.68% and a maximum removal capacity of 9.97 mg g<sup>−1</sup> were achieved. Both the Langmuir isotherm model and pseudo-second-order kinetic model exhibited good fits to the experimental data, with an estimated activation energy of 81.9 kJ mol<sup>−1</sup> and a positive enthalpy of 9.3 kJ mol<sup>−1</sup>, indicating an endothermic chemisorption process with a monolayer surface coverage of phosphate on Cry–Ca–COS. In real samples, Cry–Ca–COS demonstrated a high removal efficiency ranging from 98.48% ± 1.87%–99.16% ± 0.72%, with the adsorbed material biodegrading within 24 days under soil burial conditions. A preliminary study was conducted to explore the feasibility of utilizing phosphate-adsorbed Cry–Ca–COS as a fertilizer for cultivating water spinach (Ipomoea aquatica Forsk.), and further in-depth investigation is required for a comprehensive report in the future. Thus, Cry–Ca–COS emerges as an environmentally friendly and effective tool for phosphate removal and recovery.
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    Starch Biocryogel for Removal of Methylene Blue by Batch Adsorption
    (2022-12-01)
    Taweekarn, Tarawee
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    Wongniramaikul, Worawit
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    Boonkanon, Chanita
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    Phanrit, Chonthicha
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    Sriprom, Wilasinee
    A green monolithic starch cryogel was prepared and applied for the removal of methylene blue (MB) using a batch system. The influence of various experimental parameters on MB adsorption was investigated. High removal efficiency (81.58 ± 0.59%) and adsorption capacity (34.84 mg g<sup>−1</sup>) were achieved. The Langmuir model better fitted the experimental data (determination coefficient (R<sup>2</sup>) = 0.9838) than the Freundlich one (R<sup>2</sup> = 0.8542), while the kinetics of MB adsorption on the cryogel followed a pseudo-second-order model. The adsorption process was spontaneous and endothermic with an activation energy of 37.8 kJ mol<sup>−1</sup> that indicated physical adsorption. The starch cryogel was used for MB removal from a wastewater sample collected from a local Batik production community enterprise in Phuket, Thailand, and a removal efficiency of 75.6% was achieved, indicating that it has a high potential as a green adsorbent for MB removal.
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    Calcium silicate hydrate–embedded porous concrete for efficient phosphate removal and recovery in concentrated eluates
    (2026-01-01)
    Wongniramaikul, Worawit
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    Choodum, Aree
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    Pasitsuparoad, Pakorn
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    Cotchim, Suparat
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    Phosphate remediation and recovery from wastewater remain challenging due to limitations in adsorbent stability and real–world applicability. This study presents a sustainable porous concrete–calcium silicate hydrate (PC–CSH) column engineered for continuous–flow phosphate removal and resource recovery. Synthesized CSH nanoparticles were incorporated into a porous cement matrix, and comprehensive characterization confirmed the formation of calcium phosphate phases, including hydroxyapatite (HAP), CaHPO₄, and Ca(H₂PO₄)₂. The results indicate that surface-induced microprecipitation, driven by Ca²⁺ and OH⁻ released from both added and in situ–formed CSH, is the dominant removal mechanism. Externally added nanoparticles contributed 40.05% of total uptake, while the remainder originated from CSH generated during cement hydration. Breakthrough analysis showed that increasing column height enhanced longevity, whereas higher influent phosphate concentration and flow rate accelerated saturation. Under optimal conditions (7.5 cm column, 50 mg L⁻¹ phosphate, 10 mL min⁻¹ flow), the system achieved >99% removal with a total adsorption capacity of 3599.7 mg. The nonlinear Yoon–Nelson model best described the breakthrough behavior. Application to real municipal wastewater (initial phosphate 4.57 mg L⁻¹) achieved 99.3% removal with minimal influence from coexisting anions (SO₄²⁻, NO₃⁻, CO₃²⁻). Phosphate was efficiently recovered using 0.5 M HCl (100.4% desorption), and performance was restored by reloading fresh PC–CSH slurry. The column retained 73.9% phosphate removal efficiency after four adsorption–desorption cycles with real wastewater, demonstrating excellent reusability and practical potential. Overall, the PC–CSH column offers a robust, semi–regenerable platform for sustainable phosphate mitigation and recovery in wastewater treatment.
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    Item type:Publication,
    Continuous Phosphate Removal and Recovery Using a Calcium Silicate Hydrate Composite Monolithic Cryogel Column
    (2023-02-01) ;
    Wongniramaikul, Worawit
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    Taweekarn, Tarawee
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    Kleangklao, Bussakorn
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    Pisitaro, Wachiraporn
    Toward the development of a practical and green approach for removing phosphate from water, a monolithic cryogel based on starch and calcium silicate hydrate (Cry–CSH) was employed as a phosphate adsorbent in a continuous flow system for the first time. The influence of flow rate, initial phosphate concentration, and adsorbent height on the adsorption efficiency was investigated. As the rate of flow and the initial concentration of phosphate increased, the total quantity of adsorbed phosphate dropped; however, the performance of the column was greatly enhanced by an increase in adsorbent height. The experimental data fit the Adams–Bohart model better than the Thomas and Yoon–Nelson models at the beginning of the adsorption process. To evaluate its applicability, the continuous flow system based on the monolithic Cry–CSH column was applied for the removal of phosphate from the discharge effluent of the Patong Municipality Wastewater Treatment Plant (Phuket, Thailand), achieving an excellent total adsorption of 94.61%.
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    Innovative eco-friendly methyl orange removal: Mechanism, kinetic, and thermodynamic study using starch cryogel-integrated mesoporous silica nanoparticles
    (2024-11-15)
    Taweekarn, Tarawee
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    Wongniramaikul, Worawit
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    Sriprom, Wilasinee
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    Limsakul, Wadcharawadee
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    This study introduces a novel, eco−friendly composite, uncalcined mesoporous silica nanoparticles incorporated into a starch cryogel (MSNs-Cry), designed for the effective removal of methyl orange (MO) from water. MSNs−Cry integrates uncalcined mesoporous silica nanoparticles (MSNs) within a starch cryogel network, leveraging the high adsorption capacity of MSNs. The composite achieved a maximum adsorption capacity of 18.98 mg g⁻<sup>1</sup> and demonstrated high removal efficiencies of 99.00 % ± 0.21 % in synthetic water (10 mg L<sup>−1</sup> MO) and 92.77 % ± 1.76 % in real wastewater containing 0.43 mg L<sup>−1</sup> MO. The Langmuir isotherm model provided a superior fit (R<sup>2</sup> = 0.9930) compared to the Freundlich model (R<sup>2</sup> = 0.9180), and the adsorption kinetics followed a pseudo−second−order model (R<sup>2</sup> = 0.9917). The primary adsorption mechanisms included electrostatic attraction, hydrophobic interactions, and hydrogen bonding. The process was endothermic (ΔH° = 31.3 kJ mol<sup>−1</sup>), spontaneous, and more favorable at higher temperatures (ΔG° = −34.2 to −38.6 kJ mol<sup>−1</sup> at 298–318 K). In the presence of sodium silicate at 13.1 times the MO concentration, removal efficiency drops by 35.77 %, and with sodium sulfate and urea at 100 times the MO concentration, it decreases by 8.65 %. Despite these challenges, MSNs−Cry effectively removes MO in the presence of the anionic dye Congo Red and metal ions, demonstrating its selective adsorption capabilities. The tablet form of MSNs−Cry prevents the loss of uncalcined MSNs, mitigating potential environmental and operational impacts. Additionally, the composite's effectiveness at a natural pH of 6.65 eliminates the need for pH adjustment, offering a cost−effective solution for real−world applications. This study establishes MSNs−Cry as a promising material for sustainable water purification.