Correlation between microstructure and dissolution property of magnesium hydroxide synthesized via magnesia hydroxylation: Effect of hydration agents

Tang, Xiaojia; Du, Zhongyuan; Zhu, Yimin; Liu, Peng-Fei; Li, Xiaoyi; Xu, Xuelu; Zhao, Yuzhe; Kuang, Haibo

doi:10.1016/j.jclepro.2019.119371

Cited by 19 publications

(11 citation statements)

References 37 publications

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“…After the geometry optimization of Dmol3 module, the lattice parameters of the unit cell were as follows: a = b = 3.1879 Å, c = 4.797 Å, α = β = 90°, and γ = 120°. In contrast to the experimental data of MH ( a = b = 3.150 Å, c = 4.770 Å, α = β = 90°, and γ = 120°), the relative error ( R ) for optimized lattice parameters ( R a = R b = 1.20%; R c = 0.57%) was below 3% according to eq , complying with the required accuracy of the simulation . The simulation details are shown in Table . R = L normalw normalo normalr normalk − L normale normalx normalp normale normalr normali normalm normale normaln normalt L normale normalx normalp normale normalr normali normalm normale normaln normalt × 100 % where R denotes the relative error, L work denotes the lattice parameters of this work ( a , b , c ), and L experiment denotes the lattice parameters from experimental data ( a , b , c ).…”

Section: Methodsmentioning

confidence: 79%

Effects of Flotation Reagents on the Morphology of Magnesium Hydroxide: Experimental and Simulation Study

Shi

Chen

Sun

et al. 2023

Ind. Eng. Chem. Res.

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The flotation process to extract potassium salt from carnallite ores could produce the MgCl 2 mother liquor with flotation reagents�octadecyl amine hydrochloride (ODA) and dodecyl morpholine (DMP). The organic impurities would further affect MgCl 2 resource-integrated utilization for preparing magnesium hydroxide (MH). In this study, the effects of flotation reagents with different concentrations on the morphology of MH were investigated at a hydrothermal temperature of 200 °C for 6 h with the hydrothermal medium of a 4 mol/L NaOH solution. It was observed that the average thickness of MH crystal plates increased and the morphology of crystals changed from regular hexagonal plates to irregular polygonal plates with the increase of ODA and DMP concentrations. Molecular dynamics (MD) simulation was applied to further explain the effect mechanism. The results indicated that ODA and DMP molecules were more likely to be adsorbed on the (1 1 0) plane in contrast to the (0 0 1) plane due to the larger absolute values of adsorption energy on the (1 1 0) plane. The long carbon chains far away from the (1 1 0) plane would form steric hindrance to affect the growth rate of MH crystals in the [1 1 0] direction.

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Section: Methodsmentioning

confidence: 79%

Effects of Flotation Reagents on the Morphology of Magnesium Hydroxide: Experimental and Simulation Study

Shi

Chen

Sun

et al. 2023

Ind. Eng. Chem. Res.

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“…[ 35,48 ] In addition, the new characteristic peak of APM60 and APM40P20 composite aerogels at 3698 cm −1 is the O–H stretching vibration band of MH, which proved the successful in situ formation of MH in composite aerogels. [ 44 ] Meanwhile, the O–H stretching vibration band moved from 3433 to 3425 cm −1 (Figure 5B) and 3429 cm −1 (Figure 5C), indicating the formation of hydrogen bond between AG/PVA and MH/Pal. [ 42,48 ]…”

Section: Resultsmentioning

confidence: 99%

“…[ 42 ] The diffraction peaks of APM60, APM55P5, APM50P10, and APM40P20 at 2 θ of 18.58°, 37.96°, 50.88°, 58.70°, 64.12°, 68.10°, and 72.10° correspond to the (001), (101), (102), (110), (111), (103), and (201) crystal planes of MH, respectively, [ 43 ] indicating that MH was successfully in situ generated in the AG/PVA composite aerogel matrix. The diffraction peak at 2 θ = 42.9° (200 crystalline plane) belongs to the characteristic peak of MgO [ 44 ] and gradually weakens with the decrease in MgO content, which can be attributed to the incomplete hydration of MgO. In addition, the diffraction peaks of APM55P5, APM50P10, and APM40P20 at 2 θ = 8.33° are the characteristic peaks of Pal, [ 36,42 ] which proved that Pal was successfully introduced into composite aerogels.…”

Section: Resultsmentioning

confidence: 99%

Facile construction of flame‐retardant, heat‐insulating agar/polyvinyl alcohol composite aerogels via in situ formation of magnesium hydroxide and palygorskite‐assisted strategy

Guo

Xia

Chen

et al. 2022

Vinyl Additive Technology

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Natural polymer aerogel is a candidate material with broad application prospects in the field of building insulation because of its lightweight, low thermal conductivity, and biodegradability. However, poor mechanical properties and easy combustion greatly limit its development. In this work, magnesium hydroxide (MH) was synthesized in situ in the agar (AG)/polyvinyl alcohol (PVA) composites using magnesium oxide as raw material. Furthermore, the one-dimensional rod-like nanoclay palygorskite (Pal) was introduced into the composites. A series of composite aerogels with different ratios of MH and Pal were prepared by a simple freeze-drying process, and their microstructure, mechanical properties, water resistance, thermal stability, thermal insulation, and flame-retardant properties were investigated. Cone calorimeter tests showed that MH/Pal synergistic flame retardant had excellent performance in reducing heat release rate and suppressing smoke. The AG/PVA/MH/Pal composite samples had a limiting oxygen index of 37.5% and achieved V-0 rating in the UL-94 test. In addition, the introduction of MH and Pal has enabled the AG/PVA composite aerogels to exhibit superior mechanical, thermal insulation, and water stability properties. K E Y W O R D Sflame-retardant polymer, in situ generation, magnesium hydroxide, palygorskite | INTRODUCTIONAerogels, a type of material with porous structure, are made from SiO 2 or polymers. [1][2][3] The ultra-low density and ultra-high porosity considerably reduce the quality and thermal conductivity of aerogels. [4,5] Polymer-based aerogels have shown excellent effects in the field of heat insulation compared to traditional insulation materials such as rock wool board, glass wool, and polystyrene foam. [6,7] They have broad application prospects in the fields of building energy-saving insulation and thermal pipeline. [8,9] Among polymer-based aerogels, biodegradable matrix materials such as polyvinyl alcohol (PVA), [9,10] cellulose, [11] and starch [12] have attracted wide attention due to friendly environment. [13] Agar (AG), a natural polymer, is soluble in hot water and can form hydrogel after cooling, [14,15] and after freeze-drying, AG-based aerogels can be formed. [16] However, pure AG

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“…On the other hand, CM is attained as a by-product of sinter production at sleeve filters that retain fines at furnaces' overflow 5 . Because of the lower temperatures involved (700-1000ºC), the crystalline structure of the MgO attained after the MgCO 3 decarbonation remains highly defective and its particles show a much higher specific surface area and reactivity due to the large fraction of mesopores and numerous cracks formed during gas evolution (Figure 1b) 23,27,28,40 .…”

Section: Mgohmentioning

confidence: 99%

“…MgOH + ions then dissolve in water up to the point of saturation, significantly increasing both medium's ionic conductivity and strength [22][23][24][25] . Such a condition is known as the induction period 26,27 and can last from a few seconds to up to several hours 7 , depending on the MgO source 26,28 , its physical properties 29,30 , and test conditions 29,31,32 . The saturated solution then begins to form magnesium hydroxide (Mg(OH) 2 ) or brucite [33][34][35][36][37][38][39] , whose particles precipitate (Equation 2) at unreacted MgO surfaces.…”

Section: Introductionmentioning

confidence: 99%

Hydroxylation Studies on High-Solid Load Magnesia Aqueous Suspensions

Salomão

Fernandes

2023

Mat. Res.

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The magnesia (MgO) hydroxylation behavior in dilute suspensions (below 50% volumetric solid loads) has been extensively studied over the past decades due to its role in refractory castables. However, its equivalent effects on concentrated systems have not been analyzed in such a systemic way, although they are known to be as or more deleterious than those observed in dilute systems. This study focuses on the hydroxylation behavior of different sources of magnesia (sinter and caustic magnesia) in aqueous suspensions prepared at various solids concentrations (17-96 vol%) and shaped by distinct methods. They were analyzed by thermogravimetry, apparent volumetric expansion measurements, X-ray diffraction, scanning electron microscopy, and in situ temperature measurements during curing. The ratio between experimental and theoretical extents of the hydroxylation degree resulted in the reaction yield. A comparison between samples containing the same water amount revealed those with caustic magnesia showed a faster evolution of hydroxylation degree, apparent volumetric expansion, and higher maximum internal temperature during curing. In both systems, the yield levels of compositions of heavier solid loads were higher, despite the small quantity of hydroxylation products formed. Significant differences in the products' microstructure were observed and related to the ions' mobility toward crystallization nuclei.

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Correlation between microstructure and dissolution property of magnesium hydroxide synthesized via magnesia hydroxylation: Effect of hydration agents

Cited by 19 publications

References 37 publications

Effects of Flotation Reagents on the Morphology of Magnesium Hydroxide: Experimental and Simulation Study

Effects of Flotation Reagents on the Morphology of Magnesium Hydroxide: Experimental and Simulation Study

Facile construction of flame‐retardant, heat‐insulating agar/polyvinyl alcohol composite aerogels via in situ formation of magnesium hydroxide and palygorskite‐assisted strategy

Hydroxylation Studies on High-Solid Load Magnesia Aqueous Suspensions

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