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Subject: search.filters.subject.Oyster shell

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    Effect of fortified calcium compounds from oyster shell on the quality of tapioca pearls
    (2025-01-15)
    Meeparn, Parinda
    ;
    Aenglong, Chakkapat
    ;
    Ratanasumawong, Savitree
    ;
    Klaypradit, Wanwimol
    ;
    Kerdpiboon, Soraya
    This study aimed to determine the effect of calcium fortification from dried oyster shells (DOS) and calcined oyster shells (COS) at concentrations of 2, 4 and 6 %(w/w) on physical and chemical properties of tapioca pearls. The results showed that the optimal cooking time of TP-COS decreased compared to TP-DOS and TP (control). The TP-DOS and TP-COS exhibited a remaining calcium content ranging from 8.39 to 41.03 mg/g. During seven days of refrigerated storage, TP-COS showed delayed hardness along with decreases in both the enthalpy of gelatinization and retrogradation. The functional groups observed in TP-DOS and TP-COS showed varying intensities compared to TP. Morphology images depicted the distribution of DOS and COS within tapioca pearls, revealing that TP-DOS and TP-COS possessed a denser and more compact structure. The results suggest that COS fortification could improve the nutritional value and delay the change in the texture of tapioca pearls after storage.
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    Recrystallization of Triple Superphosphate Produced from Oyster Shell Waste for Agronomic Performance and Environmental Issues
    (2022-02-01)
    Seesanong, Somkiat
    ;
    Seangarun, Chaowared
    ;
    Boonchom, Banjong
    ;
    Sronsri, Chuchai
    ;
    Laohavisuti, Nongnuch
    Calcium dihydrogen phosphate monohydrate (Ca(H<inf>2</inf>PO<inf>4</inf>)<inf>2</inf>·H<inf>2</inf>O) (a fertilizer) was successfully synthesized through a recrystallization process using prepared triple superphosphate (TSP) derived from oyster shell waste as the starting material. This bio-green, eco-friendly process to produce an important fertilizer can promote a sustainable society. The shell-waste-derived TSP was dissolved in distilled water and kept at 30, 50, and 80<sup>◦</sup>C. Non-soluble powder and TSP solution were obtained. The TSP solution fractions were then dried, and the recrystallized products (RCP30, RCP50, and RCP80) were obtained and confirmed as Ca(H<inf>2</inf>PO<inf>4</inf>)<inf>2</inf>·H<inf>2</inf>O. Conversely, the non-soluble products (NSP30, NSP50, and NSP80) were observed as calcium hydrogen phosphate dihydrate (CaHPO<inf>4</inf>·2H<inf>2</inf>O). The recrystallized yields of RCP30, RCP50, and RCP80 were found to be 51.0%, 49.6%, and 46.3%, whereas the soluble percentages were 98.72%, 99.16%, and 96.63%, respectively. RCP30 shows different morphological plate sizes, while RCP50 and RCP80 present the coagulate crystal plates. X-ray diffractograms confirmed the formation of both the NSP and RCP. The infrared adsorption spectra confirmed the vibrational characteristics of HPO<inf>4</inf><sup>2−</sup>, H<inf>2</inf>PO<inf>4</inf><sup>−</sup>, and H<inf>2</inf>O existed in CaHPO<inf>4</inf>·2H<inf>2</inf>O and Ca(H<inf>2</inf>PO<inf>4</inf>)<inf>2</inf>·H<inf>2</inf>O. Three thermal dehydration steps of Ca(H<inf>2</inf>PO<inf>4</inf>)<inf>2</inf>·H<inf>2</inf>O (physisorbed water, polycondensation, and re-polycondensation) were observed. Ca(H<inf>2</inf>PO<inf>4</inf>)<inf>2</inf> and CaH<inf>2</inf>P<inf>2</inf>O<inf>7</inf> are the thermodecomposed products from the first and second steps, whereas the final product is CaP<inf>2</inf>O<inf>6</inf>.
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    Arsenic adsorption using the adsorbent synthesised from oyster shell
    (2017-01-01)
    Khownpurk, Pichnipa
    ;
    Wongpromrat, Wichitra
    ;
    Chandra-Ambhorn, Walairat
    Ground oyster shells were calcined and used as an adsorbent to remove As (III) from contaminated water. Adsorption experiment was performed by batch tests. The effect of pH on the adsorption performance was investigated. The result showed that at the initial concentration of 100 mg/L, over the pH range of 5-11, the highest efficiency was obtained at pH 11. The experimental data better correlated with pseudo-second order model. The maximum adsorption capacity (q<inf>m</inf>) of approximately 195.5 mg/g was obtained at pH 11.