DSpace-CRIS

Now showing 1 - 3 of 3

Some of the metrics are blocked by your
consent settings
Magnetic calcium silicate hydrate–oyster shell waste nanocomposite for phosphate removal and recovery: RSM-based optimization, mechanism, and real water application
(2025-09-01)
Boonkanon, Chanita
;
Wongniramaikul, Worawit
;
Phawachalotorn, Chanadda
;
Limwongsakorn, Somsak
;
Choodum, Aree
Magnetic nanocomposites offer an effective strategy for phosphate removal from wastewater, preventing eutrophication and enabling phosphate recovery for reuse as fertilizer—supporting a zero-waste approach. In this study, a novel hybrid nanocomposite composed of magnetized calcined oyster shell waste and calcium silicate hydrate (M-COS-CSH) was synthesized through a simple process completed within 5.2 h. Response Surface Methodology was employed for optimization: a Central Composite Design determined the optimal FeCl₃ and COS ratios, while a Box–Behnken Design optimized adsorption conditions including adsorbent dose (20–100 mg), initial phosphate concentration (10–90 mg L−1), contact time (15–75 min), and pH (3−11). Under optimal conditions (60 mg adsorbent, 10 mg L−1 phosphate, 45 min, pH 6.28), M-COS-CSH achieved a predicted maximum removal efficiency of 97.30 %. An experimental removal efficiency of 98.06 % ± 0.19 % was obtained under the same conditions without pH adjustment (pH 6.84), offering a cost advantage. The adsorption process closely followed the Langmuir isotherm model (R2 = 0.9963), with a maximum adsorption capacity of 161.29 mg g−1, and was best described by the pseudo-second-order kinetic model (R2 = 1.0000). Characterization suggested a mechanism involving surface microprecipitation and inner-sphere complexation. Thermodynamic analysis confirmed the process to be endothermic and spontaneous (ΔG°: −9.97 to −10.84 kJ mol−1; ΔH°: 3.00 kJ mol−1; ΔS°: 43.52 J mol−1 K−1). M-COS-CSH achieved phosphate removal ranging from 70.81 % ± 2.47 % to 94.24 % ± 0.39 % in real water samples. Even in the presence of competing anions at fivefold phosphate concentration, removal efficiency remained high (93.58 % ± 0.32 %), confirming the material's strong selectivity and suitability in complex matrices.
2
Some of the metrics are blocked by your
consent settings
Effective recovery of phosphate from wastewater using biodegradable calcium-rich shell wastes composite macroporous cryogel
(2024-06-20)
Kaewnoo, Satabodee
;
Wongniramaikul, Worawit
;
Boonkanon, Chanita
;
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−1 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−1 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−1 and a positive enthalpy of 9.3 kJ mol−1, 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.
Some of the metrics are blocked by your
consent settings
Sugarcane bagasse-derived hydrochar: Modification with cations to enhance phosphate removal
(2021-09-01)
Thawornchaisit, Usarat
;
Onlamai, Tanrawee
;
Phurkphong, Nontakorn
;
Sukharom, Rawiwan
Cation modified hydrochars were synthesized by hydrothermal carbonization (HTC) of sugarcane bagasse, followed by impregnation of three different cations (Ca, Mg, and Fe) or co-precipitation of Fe3+ and Fe2+. HTC enhanced the hydrochar surface area and increased the enrichment of oxygen functional groups on the hydrochar surface confirmed by FTIR. The oxygen functional groups further improve the adsorption capacity for cations during hydrochar chemical modification. Physical appearance, FTIR and XRF confirmed that Ca2+, Mg2+ and Fe2+ or Fe3+ were well retained in the bagasse-derived hydrochar. The pH<inf>pzc</inf> values of all chemically modified hydrochars were greater than the unmodified hydrochar or bagasse alone. Modification with different cations improved phosphate uptake capacity. The Fe-modified hydrochar with about 45-50% Fe content showed greater phosphate removal efficiency than Ca-and Mg-modified hydrochars. In addition, hydrochars decorated by impregnation of Fe3+ demonstrated better phosphate removal than ones produced by co-precipitation of Fe3+ and Fe2+. Thus, chemically modified hydrochars could be used as an environmentally alternative adsorbent for phosphate removal from aqueous solutions.

KMITL

Browse

Filters

Settings

Sort By

Results per page

Search Results