The Effect of Solvent Polarity on Phase Transformation of Citrogypsum via Hydrothermal Process

Sirimahasal, Thanakit; Kalhong, Yutthana; Simasatitkul, Lida; Pranee, Siriporn; Seeyangnok, Samitthichai

doi:10.4028/www.scientific.net/kem.803.351

Cited by 6 publications

(4 citation statements)

References 16 publications

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“…In the other hand, when 4M and 5M sodium chloride solutions are employed in the reaction process, the transformation of citrogypsum to α-HH are achieved which confirmed by the absent of characteristic peaks of DH, and the exothermic peak are presented at 290 to 300ᵒC. Hence, it is concluded that the citrogypsum is successfully transformed of to α-HH [2][3]. The SEM micrographs in Fig.…”

Section: Resultsmentioning

confidence: 74%

“…In addition, α-HH is usually used because of better workability and higher strength. The preparation of single crystal α-HH from citrogypsum raw material [1][2][3], hydrothermal, is a simple and effective at a high temperature and pressure. The previously work of the flue gas desulfurization gypsum (FGD gypsum) transformation to α-HH in saline solution are successfully done, however the citrogypsum from citric acid production could not be converted to α-HH under this condition.…”

Section: Introductionmentioning

confidence: 99%

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Modification and Scale-Up Process of Citrogypsum to α-Calcium Sulfate Hemihydrate over Sodium Chloride Solution

Sirimahasal

Kalhong

Simasatitkul

et al. 2020

MSF

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It describes the development of a marketable citrogypsum which is also a by-product of citric acid production from laboratory scale to pilot scale. The modification of b-phase citrogypsum was carried out in different sodium chloride solution at 95oC for 7 hours under atmospheric pressure to α-calcium sulfate hemihydrate (α-CaSO4∙0.5H2O, α-HH). This can be achieved in the laboratory scale experiment. The phase analysis of a citrogypsum was confirmed by XRD technique demonstrated that mostly made up of calcium sulfate dihydrate (CaSO4∙2H2O, DH). The dehydration and phase transformation of citrogypsum to α-HH were conducted by DSC thermograms which were presented two endothermic peaks in the range 150-180oC of citrogypsum and an exothermic peak at 290 to 300oC, resulting that the product being α-HH when the 4M and 5M sodium chloride solutions were used. The outcome products were presented in a plate-like shape of citrogypsum but a hexagonal shape of α-HH. The experiment scaled up for modification of DH up to 100% in a batch reactor at the same condition with the 4M sodium chloride solution. The results showed that α-HH was obtained within 15 to 60 min after that calcium sulfate anhydrous (CaSO4, AH) had been formed. The non-isothermal of DSC was an adapted method to investigate kinetics study of DH to α-HH transformation under the optimum condition with a model fitting dα/dt = -3k (α2) for predicting the process compared to the experiment values. In addition, the coefficient of determination (R2) from estimation and experiment value was 0.9940. Hence, the model equation was completely represent data.

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Section: Resultsmentioning

confidence: 74%

Section: Introductionmentioning

confidence: 99%

Modification and Scale-Up Process of Citrogypsum to α-Calcium Sulfate Hemihydrate over Sodium Chloride Solution

Sirimahasal

Kalhong

Simasatitkul

et al. 2020

MSF

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“…Цитрогипс, являющийся отходом биохимического производства лимонной кислоты [16,17] (Белгород, Россия), служил исходным материалом для изготовления датчиков влажности воздуха. Физические и химические свойства цитрогипса описаны в [18].…”

Section: материалы и методыunclassified

Свойства Цитрогипса И Возможности Его Применения В Технике

Никуличева,

Захвалинский,

Пилюк

et al. 2023

Журнал Технической Физики

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At present, the problem of using as functional materials such materials that are a by-product of technological processes and accumulate in the form of production waste is becoming more relevant. We have studied two groups of samples. The first group became the basis for a new material for the air humidity sensor, which was obtained from the waste products of citric acid production. Samples of citrogypsum (calcium sulfate dihydrate, i.e. CaSO42H2O) doped with copper sulfate (CuSO45H2O) were prepared. The dependence of the impedance on the relative humidity of samples of three thicknesses was carried out. The frequency dependences of complex resistance and relative permittivity on relative humidity are measured. The second group of samples obtained from citrogypsum was a powder consisting of CaSO42H2O whiskers. Whiskers CaSO42H2O were used to create composites based on epoxy resin. An improvement in the properties of the composite was recorded in the study of tensile and compressive stresses of the samples. This article shows the possibility of practical application of (CaSO42H2O)0.95–(CuSO45H2O)0.05 as a new air humidity sensor material and improvement of the mechanical properties of the composite based on epoxy resin and CaSO42H2O whiskers.

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“…However, CG so synthesized is not industrially acceptable because he physical and chemical properties are inferior to natural gypsum. It cannot be used to form white products [3].…”

Section: Introductionmentioning

confidence: 99%

The Phase Morphology of Citrogypsum Waste Controlled by a Hydrothermal Process in Ethylene Glycol/Water Solutions

Sirimahasal

Kalhong

Simasatitkul

et al. 2019

KEM

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The acid purification of calcium citrate from citric acid production using sulfuric acid as a reagent resulted in citrogypsum waste. The identification of citrogypsum by XRD technique indicates that the main component consists of CaSO4∙2H2O (DH). Furthermore, the comparison of the colours between citrogypsum and natural gypsum are also different. Hence, this research mainly focused on the phase transformation of DH to α-CaSO4 ∙0.5H2O (α-HH) due to high strength and heat resistant. The preparation of α-HH carry out in different volume ratios of ethylene glycol (EG): water solutions at 95oC for 7 hrs under atmospheric pressure. The FT-IR spectra of DH and α-HH results reveal that the absorption frequencies at 1700 and 1800 cm-1 of –OH group are 0.5 and 1.5 water molecule in CaSO4 respectively. TGA thermograms show the theoretical crystal water content of DH approximately 20.1 wt% and the converted α-HH about 4-5 wt%. DSC thermograms of the citrogypsums show two endothermic peaks regarding to two steps of water molecule loss at 151.2oC and 168.5oC respectively. In addition, the α-HH shows exothermic peak at 238.7oC. The morphology of citrogypsum and α-HH are observed by SEM, showing the plate-like shape of citrogypsum and hexagonal shape of α-HH. Moreover, the products could be applied to several other industries for increasing the value and reducing the environmental concerns.

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The Effect of Solvent Polarity on Phase Transformation of Citrogypsum via Hydrothermal Process

Cited by 6 publications

References 16 publications

Modification and Scale-Up Process of Citrogypsum to α-Calcium Sulfate Hemihydrate over Sodium Chloride Solution

Modification and Scale-Up Process of Citrogypsum to α-Calcium Sulfate Hemihydrate over Sodium Chloride Solution

Свойства Цитрогипса И Возможности Его Применения В Технике

The Phase Morphology of Citrogypsum Waste Controlled by a Hydrothermal Process in Ethylene Glycol/Water Solutions

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