Controlling the reactivity of silicate solutions: A FTIR, Raman and NMR study

Vidal, L.; Joussein, Emmanuel; Colas, Maggy; Cornette, Julie; Sanz, J.; Sobrados, Isabel; Gelet, J-L.; Absi, Joseph; Rossignol, Sylvie

doi:10.1016/j.colsurfa.2016.05.039

Cited by 83 publications

(32 citation statements)

References 40 publications

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“…For example, PVA‐H aluminosilicate powders have slightly higher deshielding of their 29 Si nuclei, as seen in Table . Moreover, when compared to samples synthesized with high PVA polymer contents, samples synthesized with a high pH sol‐gel aging condition and low PVA polymer contents have a reduction in the absorption peak intensities associated with Si–O–Si and Si–O–Al bonds at ~1060 cm −1 …”

Section: Discussionmentioning

confidence: 98%

“…46 Further confirming these results, FTIR results for PEG-derived geopolymer cements demonstrate geopolymer network formation as observed by peak shifts to lower wave number corresponding to the formation of Si-O-Si and Si-O-Al bonds (1120 cm −1 → 1060 cm −1 ), Table 3. 59 Contrastingly, PVA-derived geopolymer cements exhibit greater extent of silicate incorporation in the gel 1 → gel 2 evolution process as sharp and intense absorption peaks are observed to be centered around 1000 cm −1 .…”

Section: Pva)mentioning

confidence: 97%

“…Moreover, when compared to samples synthesized with high PVA polymer contents, samples synthesized with a high pH sol-gel aging condition and low PVA polymer contents have a reduction in the absorption peak intensities associated with Si-O-Si and Si-O-Al bonds at ~1060 cm −1 . 59 However, when alkali-activated, synthetic aluminosilicate powders produced with low pH sol-gel aging conditions may improve the extent of geopolymerization and dictate the F I G U R E 6 27 Al MAS NMR and 1 H- 27 (Figure 4). High absorption intensity may indicate a greater extent of silicate incorporation and content of Q 4 (4Al) units in the geopolymer cements, as previously discussed.…”

Section: Low Vs High)mentioning

confidence: 99%

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PVA‐ and PEG‐assisted sol‐gel synthesis of aluminosilicate precursors for N‐A‐S‐H geopolymer cements

et al. 2019

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This study investigates critical factors affecting polymer‐assisted sol‐gel synthesis of synthetic aluminosilicate powders that can be alkali‐activated to produce a sodium‐stabilized aluminosilicate hydrate (N‐A‐S‐H) geopolymer cement. More specifically, a 22 factorial experiment was conducted to elucidate the influence of polymer architecture (ie, poly(ethylene glycol) (PEG) vs poly(vinyl alcohol) (PVA)), polymer content (ie, low vs high ion‐to‐polymer‐oxide (I/O) atomic ratio), and sol‐gel aging pH conditions (ie, low vs high) on the atomic structure of resultant synthetic aluminosilicate powders and geopolymer cements. Molecular structure was investigated using solid‐state (single‐pulse and 1H cross‐polarization) 29Si and 27Al nuclear magnetic resonance (NMR) and Fourier‐transform infrared (FTIR) spectroscopy. The mineralogy of geopolymer cements was assessed with X‐ray diffraction and compared to alkali‐activated metakaolin‐based cements of equivalent stoichiometry. Results demonstrate that polymer architecture (PEG vs PVA) is a key factor in producing (a) undesirable phase segregation (ie, γ‐alumina) and (b) incomplete dehydroxylation (ie, vicinal silanol) in synthetic aluminosilicate powders. More specifically, PEG‐derived aluminosilicate powders yield partial dissolution and produce geopolymer cements with variable silicate incorporation. Contrastingly, PVA‐derived aluminosilicate powders produce geopolymer cements with identical mineralogy to that of metakaolin‐based geopolymer cements and exhibit both Brønsted‐acid sites near the aluminum nuclei and geminal silanol groups. Sol‐gel aging pH conditions reveal the ability to influence the hydroxyl group content, which is an important factor affecting the durability of cementitious materials. Lastly, three plausible mechanisms of metal complexation are hypothesized to permit incorporation of solubilized metal ions via a polymer‐assisted sol‐gel process.

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Section: Discussionmentioning

confidence: 98%

Section: Pva)mentioning

confidence: 97%

Section: Low Vs High)mentioning

confidence: 99%

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PVA‐ and PEG‐assisted sol‐gel synthesis of aluminosilicate precursors for N‐A‐S‐H geopolymer cements

et al. 2019

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“…The wide peak of the adsorbent at 1000-1100 cm −1 was attributed to the breaking of the mesh structure of quartz during heating to form disordered SiO 4 [14]. The tensile peak at 887 cm −1 was attributed to Si-O-Na [26]. The spectra also showed a Si-OH stretching peak at 970 cm −1 [27,28], and Si-OH and H-O-H stretching vibrational peaks at 1454 cm −1 and 3450 cm −1 , respectively [29][30][31].…”

Section: Characterization Of Ashmamentioning

confidence: 99%

A Functionalized Silicate Adsorbent and Exploration of Its Adsorption Mechanism

et al. 2020

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Active silicate materials have good adsorption and passivation effects on heavy metal pollutants. The experimental conditions for the preparation of active silicate heavy metal adsorbent (ASHMA) and the adsorption of Cu(II) by ASHMA were investigated. The optimum preparation conditions of ASHMA were as follows: 200 mesh quartz sand as the raw material, NaOH as an activating agent, NaOH/quartz sand = 0.45 (mass fraction), and calcination at 600 • C for 60 min. Under these conditions, the active silicon content of the adsorbent was 22.38% and the utilization efficiency of NaOH reached 89.11%. The adsorption mechanism of Cu(II) on the ASHMA was analyzed by the Langmuir and Freundlich isotherm models, which provided fits of 0.99 and 0.98, respectively. The separation coefficient (R L ) and adsorption constant (n) showed that the adsorbent favored the adsorption of Cu(II), and the maximum adsorption capacity (Q max ) estimated by the Langmuir isotherm was higher than that of 300 mg/L. Furthermore, adsorption by ASHMA was a relatively rapid process, and adsorption equilibrium could be achieved in 1 min. The adsorbents were characterized by FT-IR and Raman spectroscopy. The results showed that the activating agent destroyed the crystal structure of the quartz sand under calcination, and formed Si-O-Na and Si-OH groups to realize activation. The experimental results revealed that the adsorption process involved the removal of Cu(II) by the formation of Si-O-Cu bonds on the surface of the adsorbent. The above results indicated that the adsorbent prepared from quartz sand had a good removal effect on Cu(II).The amorphous silica structure of active silicate materials makes their reactivity much stronger than that of crystalline silica and confers these materials with excellent adsorption properties for pollutants such as heavy metals [7][8][9]. Studies have shown that the silanol groups (Si-OH) in active silicate materials are the main determinants of surface chemistry [10] and can form covalent bonds and hydrogen bonds with some ions and molecules [11]. Heavy metals such as Cu(II), Cd(II), and Pb(II) in aqueous solution were found to be removed by forming surface adsorption complexes with surface silanol [12,13]. Our team used leaching residue from lead-zinc tailings with high silicon content as a raw material to prepare an active silicate heavy metal adsorbent, which showed a very high adsorption capacity for the heavy metals Cu, Pb, Cd and Zn. The saturated adsorption capacities were 3.40, 2.83, 0.66 and 0.62 mmol/g, respectively [14].Besides, when active silicate materials are applied to the remediation of heavy metals in soil, extractable heavy metals can be transformed into forms with relatively stable valence [15,16], and the heavy metal stress and accumulation in plants can be reduced [17]. Moreover, the active silicates can be absorbed by plants as nutrient elements to form phytoliths, which play an important role in increasing grain yield and enhancing photosynthesis, pest resistance, lodging resistance, and so on...

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“…The first two assumptions are based on the totality of the results of research into aqueous solutions of WSS [1], and the third one is a quite acceptable simplification that makes the calculation much easier and partially relies on the results of experimental studies [9,10]. Molar concentrations of silica and cation, as well as the magnitudes of constants of dissociation and polycondensation of silanol groups, were used as source data.…”

Section: Modeling a Rheological Anomaly In The System Na 2 O-sio 2 -Nmentioning

confidence: 99%

Modeling a rheological anomaly in the system Na2O – SiO2 – NH3 – ZnO – H2O

Maliavski¹,

Zhuravlova²

2019

EEJET

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Пропонується унiверсальна розрахункова модель для теоретичного опису структурних i фiзико-хiмiчних властивостей водних розчинiв модифiкованих силiкатiв за участю комплексоутворювачiв. Модель враховує три типи рiвноваг: кислотно-основнi, метало-комплекснi i, для кремнекисневих анiонiв (ККА), також полiконденсацiйнi. Розроблений математичний апарат допускає застосування моделi практично до будь-яких типiв рiдких стекол та їх сумiшей. Для окремого випадку натрiй-цинк-амонiйного рiдкого скла модель передбачає чисельне рiшення системи з сiмнадцяти лiнiйних i нелiнiйних рiвнянь методом Ньютона. Нова модель була використана для пояснення спостережуваного експериментально ефекту реологiчної аномалiї в водних розчинах рiдкого скла, модифiкованого цинком i амiаком. Ефект характерний, бiльш за все, для розчинiв амiносилiкатiв, де реологiчена аномалiя пов'язана зi змiщенням при нагрiваннi молекулярно-масового розподiлу (ММР) ККА в напрямку процесу полiконденсацiї. Результати розрахункiв показують, що подiбне змiщення має мiсце також в данiй системi i пояснюється трансформацiєю амiнокомплексiв цинку в гiдроксокомплекси. Сумарний процес може бути виражений рiвнянням [Zn(NH 3) 4 ] 2+ +3OH-[Zn(OH) 3 ]-+4NH 3 , що пояснюється iстотною вiдмiннiстю величин ентальпiї утворення цих комплексiв. Це призводить до зменшення величини рН i до змiщення ММР ККА в сторону пiдвищення ступеня полiмеризацiї (зменшення середньої основностi ККА). Присутнiсть iнших комплексних частинок, таких як [Zn(NH 3) 3 ] 2+ , [Zn(OH) 4 ] 2-, [Zn(OH) 2 ] i т. д., не вiдiграє суттєвої ролi. Використання запропонованої моделi дозволило розрахувати залежностi параметрiв ММР ККА, величин рН i концентрацiй комплексних i полiконденсацiйних структур вiд складу розчину i температури. Детально простежено еволюцiю вiдносного змiсту рiзних структур, що мiстять цинк i кремнiй, в ходi змiни температури i загальної концентрацiї цинку. Зроблено висновок про те, що реологiчна аномалiя в дослiджуванiй системi iснує завдяки особливому поєднанню термодинамiчних параметрiв i навряд чи широко поширена серед метало-комплексних силiкатiв Ключовi слова: розчиннi силiкати, модифiкованi рiдкi скла, комплекси цинку, аномальна реологiя, полiконденсацiя

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Controlling the reactivity of silicate solutions: A FTIR, Raman and NMR study

Cited by 83 publications

References 40 publications

PVA‐ and PEG‐assisted sol‐gel synthesis of aluminosilicate precursors for N‐A‐S‐H geopolymer cements

PVA‐ and PEG‐assisted sol‐gel synthesis of aluminosilicate precursors for N‐A‐S‐H geopolymer cements

A Functionalized Silicate Adsorbent and Exploration of Its Adsorption Mechanism

Modeling a rheological anomaly in the system Na2O – SiO2 – NH3 – ZnO – H2O

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