L-aspartic acid: A crystal modifier for preparation of hemihydrate from phosphogypsum in CaCl2 solution

Li, Xianbo; Zhang, Qin; Zhang, Shen; Li, Longjiang; Li, Xianhai; Mao, Song

doi:10.1016/j.jcrysgro.2019.01.027

Cited by 41 publications

(19 citation statements)

References 30 publications

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“…In fact, the only difference between L-Asn and L-Asp is a NH 2 instead of an OH linked to the C=O function. Although we reported earlier that L-Asp is an effective crystal modifier [24], L-Glu and L-Asn with similar structures have not been investigated. The effect of the BA concentration on the compressive strength of hardened gypsum (CaSO4•2H2O) hydrated from α-CaSO4•0.5H2O is shown in Figure 4.…”

Section: Effect Of Amino Acid On the Crystal Habit Of α-Caso4• 05h2omentioning

confidence: 99%

“…The peak appearing at 1443 cm −1 can be assigned to the symmetric stretching vibration of COO − in amino acid. The peak located at 779 cm −1 is due to the bending vibration of COO − , which is considered to be the characteristic absorption peak of short-chain fatty acids [24]. As can be seen from Figure 12c, As PD, IPA, L-Glu, and L-Asn do not have the ability to control the crystal shape of α-CaSO4•0.5H2O particles, FTIR was also used to analyze the adsorption of these organic acids on the surface of α-CaSO4•0.5H2O.…”

Section: Control Mechanism Of Organic Acids For the Crystal Habit Of mentioning

confidence: 99%

“…The crystal habit of α-CaSO 4 •0.5H 2 O crystals can be influenced by adding citric acid (C 6 H 8 O 7 •H 2 O) [22] and sodium citrate (Na 3 C 6 H 5 O 7 •2H 2 O) [12,13]; the aspect ratio of α-CaSO 4 •0.5H 2 O crystal is decreased from 10.3 to 0.6 with the increase in the sodium citrate dosage from 0 to 0.045 wt% [23]. Recently, Li et al [24] found that L-aspartic acid (C 4 H 7 NO 4 ) is an effective crystal modifier for regulating the crystal shape of α-CaSO 4 •0.5H 2 O. Additionally, Wang et al [25] demonstrated that disodium ethylenediamine tetraacetate (C 10 H 14 N 2 Na 2 O 8 ) influences the crystal habit and nucleation of α-CaSO 4 •0.5H 2 O. In particular, Badens et al [26] investigated the influence of different organic additives on the morphology of gypsum crystals where the results showed that there is an obvious relationship between the rate retarding effect and structural matching between the crystal faces involved and the conformation of the molecule of the additive.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Molecular Structure of Organic Acids on the Crystal Habit of α-CaSO4·0.5H2O from Phosphogypsum

Zhang

2020

Crystals

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The organic acid crystal modifiers play an important role in the control of the crystal habit of α-hemihydrate gypsum (α-CaSO4·0.5H2O) from phosphogypsum, but the molecular structure characteristics of crystal modifiers have not been clarified, which makes it difficult to judge whether an organic acid has the ability to regulate the crystal habit of α-CaSO4·0.5H2O directly. In this work, the effect of organic acids with different molecular structures on the crystal habit of α-CaSO4·0.5H2O and its adsorption differences onto the α-CaSO4·0.5H2O surface were explored. The results show that the molecular structure characteristics of crystal modifiers contain two or more carboxylic groups (COOH) that are separated by two methylene or methine groups. Furthermore, organic acids with the regulation ability can adsorb on the surface of α-CaSO4·0.5H2O and change its growth habit. With the increase in the crystal modifier concentration, the α-CaSO4·0.5H2O crystals are shortened in length and enlarged in width, resulting in the decrease in aspect ratio and the increase in compressive strength. Conversely, when the adsorption of ineffective organic acids on the surface of α-CaSO4·0.5H2O was not detected, the α-CaSO4·0.5H2O crystals remained long hexagonal prisms. These results have guiding significance for the screening of novel organic acid crystal modifiers.

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Section: Effect Of Amino Acid On the Crystal Habit Of α-Caso4• 05h2omentioning

confidence: 99%

Section: Control Mechanism Of Organic Acids For the Crystal Habit Of mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Effect of Molecular Structure of Organic Acids on the Crystal Habit of α-CaSO4·0.5H2O from Phosphogypsum

Zhang

2020

Crystals

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“…Crystal modifiers such as succinic acid [10][11][12][13], maleic acid [14], citric acid [15], et al can regulate the morphology of HH from a needle-shaped particle to a short columnar crystal. Our previous research indicated that L-Aspartic acid (L-Asp) is an effective crystal modifier for the preparation of short columnar HH [16], but the effects of L-Asp on the hydration process and hardening property of HH are not clear.…”

Section: Introductionmentioning

confidence: 99%

Hydration Mechanism and Hardening Property of α-Hemihydrate Phosphogypsum

Zhang

2019

Minerals

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The hydration and hardening of α-hemihydrate phosphogypsum (HH) prepared in the absence and presence of L-Aspartic acid (L-Asp) were investigated by thermodynamic analysis, measurements of ion concentrations and crystal water content, and morphology observation. In addition, computed tomography (CT) scanning was proposed to analyze the hole characteristic of hardened gypsum in situ. The results show that HH will pass through the unstable region and the stable region of dihydrate gypsum (DH) in turn during the hydration. The hydration of HH follows the dissolution–crystallization principle; the hydration process can be divided into the dissolution stage, dissolution–crystallization stage and equilibrium stage. Compared with the HH prepared without crystal modifier, the hydration process of HH prepared with L-Asp is obviously prolonged, and the morphology of DH changes from needle-like to diamond-shape crystals with an aspect ratio of 1:1. Meanwhile, the defect-specific surface and porosity of hardened gypsum significantly decreases, achieving a more compact, hardened paste with higher compressive strength.

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“…Within this context, phosphogypsum can be classified as a mineral associated with no extraction costs. These factors determine a strong interest among researchers in the challenges of studying phosphogypsum properties and ways of phosphogypsum recycling [4][5][6][7][8][9]. One of the forms of phosphogypsum recycling is its reuse for the production of building materials, i.e.…”

Section: Introductionmentioning

confidence: 99%

Phosphogypsum recycling into inorganic dyes

et al. 2019

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Currently, chemical wastes recycling into valuable secondary products poses a pressing challenge. During phosphoric acid production from apatite raw materials, large-tonnage phosphogypsum wastes are formed, resulting in ecosystem dysfunction. Besides, such wastes occupy significant production areas. Calcium sulfate is the main component of phosphogypsum. The paper addresses the possibility of phosphogypsum reduction to calcium sulfide, which has the capacity for luminescence under UV-light. Charcoal, sucrose, and citric acid were used as reducing agents. The obtained inorganic luminescent dyes were examined using X-ray phase analysis, scanning electron microscopy (SEM), and electron probe microanalysis (EPMA). It was found that, in the presence of charcoal, the process is accompanied by an uneven distribution of calcium sulfide over the volume of the system and, as a consequence, an uneven glow of the sample. The use of citric acid and sucrose as reducing agents results in the synthesis of samples with a uniform glow. The efficiency of the calcium sulfate conversion to calcium sulfide is 51–58%. A mechanism of calcium sulfate reduction is proposed. The obtained results can serve as a basis for the development of a technology for the recycling of large-tonnage phosphoric acid production wastes into cheap and much-needed inorganic luminescent dyes.

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L-aspartic acid: A crystal modifier for preparation of hemihydrate from phosphogypsum in CaCl2 solution

Cited by 41 publications

References 30 publications

Effect of Molecular Structure of Organic Acids on the Crystal Habit of α-CaSO4·0.5H2O from Phosphogypsum

Effect of Molecular Structure of Organic Acids on the Crystal Habit of α-CaSO4·0.5H2O from Phosphogypsum

Hydration Mechanism and Hardening Property of α-Hemihydrate Phosphogypsum

Phosphogypsum recycling into inorganic dyes

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