JOINT TREATMENT OF BENTONITES WITH INORGANIC POLYELECTROLYTES  AND CATIONIC SURFACTANTS IN ORDER TO PROMOTE ORGANOCLAY EXFOLIATION

A new approach to production of organomodified bentonites is offered. Bentonites are consecutively treated with inorganic polyelectrolyte (sodium silicate solution) and quaternary ammonium salts, as a result exfoliated organoclays are obtained. An ejector set up has been used for treatment of natural bentonites. Samples of activated bentonites treated in the ejector set up with sodium silicate solution (up to 21 g of sodium silicate per 100 g of bentonite) were prepared. Structure of the obtained bentonite and organoclay samples was established by X-ray diffraction analysis. It has been shown that treatment of the activated bentonite with sodium silicate does not influence the structure of the non-modified bentonite particles, but facilitates exfoliation of clay after organomodification. Polymer composites based on EVA containing 5% wt. of bentonites were prepared by extrusion mixing. In case of non-modified bentonites microcomposites are formed. In case of organomodified bentonites, not treated with sodium silicate, intercalated nanocomposites are formed. Treatment of bentonite with sodium silicate solution and subsequent organomodification ensures the production of exfoliated nanocomposite. Mechanical properties of obtained polymer composites were determined. Incorporation of 5% wt. clays or organoclays into the polymer material leads to increase in Young modulus (up to 50%), tensile strength (up to 20%); elongation at break decreases by 10% or less. In order to ensure the more significant reinforcing effect in EVA composites optimization of the organomodified bentonite composition (selection of surfactant and its content in the organoclay) has to be carried out with account for the polymer properties.

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Pressure-Induced Geopolymerization in Alkali-Activated Fly Ash

Sustainability ◽

10.3390/su10103538 ◽

2018 ◽

Vol 10 (10) ◽

pp. 3538 ◽

Cited By ~ 4

Author(s):

Sol Park ◽

Hammad Khalid ◽

Joon Seo ◽

Hyun Yoon ◽

Hyeong Son ◽

...

Keyword(s):

Fly Ash ◽

Sodium Hydroxide ◽

Sodium Silicate ◽

Sodium Silicate Solution ◽

Silicate Solution ◽

Elevated Pressure ◽

X Ray Diffraction ◽

27Al Mas Nmr ◽

Alkali Activated

The present study investigated geopolymerization in alkali-activated fly ash under elevated pressure conditions. The fly ash was activated using either sodium hydroxide or a combination of sodium silicate solution and sodium hydroxide, and was cured at 120 °C at a pressure of 0.22 MPa for the first 24 h. The pressure-induced evolution of the binder gel in the alkali-activated fly ash was investigated by employing synchrotron X-ray diffraction and solid-state 29Si and 27Al MAS NMR spectroscopy. The results showed that the reactivity of the raw fly ash and the growth of the zeolite crystals were significantly enhanced in the samples activated with sodium hydroxide. In contrast, the effects of the elevated pressure conditions were found to be less apparent in the samples activated with the sodium silicate solution. These results may have important implications for the binder design of geopolymers, since the crystallization of geopolymers relates highly to its long-term properties and functionality.

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Formation of Geopolymers Using Sodium Silicate Solution and Aluminum Orthophosphate

Materials ◽

10.3390/ma13184202 ◽

2020 ◽

Vol 13 (18) ◽

pp. 4202

Author(s):

Stephan Partschefeld ◽

Torben Wiegand ◽

Frank Bellmann ◽

Andrea Osburg

Keyword(s):

Sodium Silicate ◽

Ph Value ◽

Sodium Silicate Solution ◽

Silicate Solution ◽

X Ray Diffraction ◽

X Ray ◽

Amorphous Phases ◽

Amorphous Aluminosilicate ◽

Kinetics Of ◽

Aluminum Orthophosphate

This paper reports the formation and structure of fast setting geopolymers activated by using three sodium silicate solutions with different modules (1.6, 2.0 and 2.4) and a berlinite-type aluminum orthophosphate. By varying the concentration of the aluminum orthophosphate, different Si/Al-ratios were established (6, 3 and 2). Reaction kinetics of binders were determined by isothermal calorimetric measurements at 20 °C. X-ray diffraction analysis as well as nuclear magnetic resonance (NMR) measurements were performed on binders to determine differences in structure by varying the alkalinity of the sodium silicate solutions and the Si/Al-ratio. The calorimetric results indicated that the higher the alkalinity of the sodium silicate solution, the higher the solubility and degree of conversion of the aluminum orthophosphate. The results of X-ray diffraction and Rietveldt analysis, as well as the NMR measurements, confirmed the assumption of the calorimetric experiments that first the aluminum orthophosphate was dissolved and then a polycondensation to an amorphous aluminosilicate network occurred. The different amounts of amorphous phases formed as a function of the alkalinity of the sodium silicate solution, indicate that tetrahydroxoaluminate species were formed during the dissolution of the aluminum orthophosphate, which reduce the pH value. This led to no further dissolution of the aluminum orthophosphate, which remained unreacted.

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Synthesis of Silica Materials from the Slurry Waste

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.765.79 ◽

2018 ◽

Vol 765 ◽

pp. 79-82 ◽

Cited By ~ 2

Author(s):

Zih Yao Shen ◽

Zhong Chen Lu ◽

Yun Chi Liu ◽

Maw Tien Lee

Keyword(s):

Silicon Carbide ◽

Sodium Silicate ◽

Liquid Mixture ◽

Sol Gel ◽

Sodium Silicate Solution ◽

Silicate Solution ◽

X Ray Diffraction ◽

Fourier Transformation Infrared Spectroscopy ◽

Solar Energy Industry ◽

Silicon Silicon

In solar energy industry, large amount of slurry wastes were produced during the wafer dicing process. The slurry waste contains silicon, silicon carbide and cutting oil. In this study, silicon in the slurry waste was treated with sodium hydroxide to produce a liquid mixture of the sodium silicate. The residue of the reaction was silicon carbide. The liquid mixture was separated to be a sodium silicate solution and used as a silica precursor for producing the silica powder and a hydrophobic silica aerogel by using the sol-gel method. The products were characterized by Fourier transformation infrared spectroscopy (FTIR) and powder X-ray diffraction (pXRD). Experimental results show that the characteristics of the products produced from the slurry waste are similar to that obtained by using the pure sodium silicate solution. It indicates that the wafer dicing slurry waste has a high potential to be a resource for other industries.

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The Effect of Milling Time on the Size of Silica Particles from Silica Sand

Materials Science Forum ◽

10.4028/www.scientific.net/msf.917.162 ◽

2018 ◽

Vol 917 ◽

pp. 162-166 ◽

Cited By ~ 2

Author(s):

Agus Ismail ◽

Insan Akbar Alamsyah ◽

Muhammad Kholil ◽

Bambang Heru Susanto ◽

Mohamad Nasikin

Keyword(s):

Silica Nanoparticles ◽

Sodium Silicate ◽

Milling Time ◽

Sol Gel ◽

Sodium Silicate Solution ◽

Silicate Solution ◽

High Energy ◽

Silica Sand ◽

X Ray Diffraction ◽

Sol Gel Process

We report a method to adjust the size of silica nanoparticles from silica sand. In this study, synthesized silica nanoparticles by sol gel process from silica sand were conducted, with previously was controlled the size of silica sand by mechanical milling. Silica sand was milled by High Energy Milling in order to reduce the size into powder form. Effect of milling time shown the content of sodium and silicon is increased in sodium silicate solution obtained from various times of silica sand milling (30, 60 and 90 minutes, respectively) which is reacted with sodium hydroxide 8 M. The result of silica nanoparticles from sol gel process of sodium silicate solution were characterized using atomic absorption spectroscopy, scanning electron microscopy and X-ray diffraction techniques. It was found that the size of silica nanoparticles could be tailored with the change of milling time.

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The Effect of Activators on the Fly Ash-Based Geopolymers

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.477.85 ◽

2011 ◽

Vol 477 ◽

pp. 85-90

Author(s):

Yun Fen Hou ◽

Dong Min Wang

Keyword(s):

Compressive Strength ◽

Fly Ash ◽

Sodium Silicate ◽

Sodium Silicate Solution ◽

Solution Concentration ◽

Silicate Solution ◽

Strength Development ◽

X Ray Diffraction ◽

Sodium Potassium ◽

Class F Fly Ash

This paper studies the influences of concentration and modulus of sodium silicate solution (Na activator) and sodium potassium silicate solution (Na-K activator) on the phase composition, microstructure and strength development in the geopolymers prepared using Class F fly ash. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and MAS NMR were utilized. It shows that the compressive strength increases while Na activator solution modulus increases, but when modulus exceeds 1.4, the compressive strength decreases, and it decreases markedly while modulus is greater than 2.0. The compressive strength improves with increase of sodium silicate solution concentration, and when concentration is 32%, compressive strength reaches the maximum, and then it reduces with concentration increment. It shows that the compressive strength increases while Na-K activator solution modulus increases, but when modulus exceeds 1.7, the compressive strength decreases, and it decreases markedly while modulus is greater than 2.0. The compressive strength improves with increase of Na-K activator solution concentration, and when concentration is 36%, compressive strength reaches the maximum. The main product of reaction in the geopolymeric material is amorphous alkali aluminosilicate gel.

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Printability and Setting Time of CSA Cement with Na2SiO3 and Gypsum for Binder Jetting 3D Printing

Materials ◽

10.3390/ma14112811 ◽

2021 ◽

Vol 14 (11) ◽

pp. 2811

Author(s):

Okpin Na ◽

Kangmin Kim ◽

Hyunjoo Lee ◽

Hyunseung Lee

Keyword(s):

3D Printing ◽

Sodium Silicate ◽

Setting Time ◽

Sodium Silicate Solution ◽

Preliminary Test ◽

Silicate Solution ◽

Calcium Sulfoaluminate Cement ◽

Calcium Sulfoaluminate ◽

Parametric Studies ◽

Binder Jetting

The purpose of this study is to optimize the composition of CSA (calcium sulfoaluminate) cement with sodium silicate (Na2SiO3) and gypsum for binder jetting 3D printing. The preliminary test was carried out with an applicator to decide the proper thickness of one layer before using the 3D printer. A liquid binder was then selected to maintain the shape of the particles. Based on the results, the optimal mixture of dry materials and a liquid activator was derived through various parametric studies. For dry materials, the optimum composition of CSA cement, gypsum, and sand was suggested, and the liquid activator made with sodium silicate solution and VMA (viscosity modified agent) were selected. The setting time with gypsum and sodium silicate was controlled within 30 s. In case of the delayed setting time and the rapid setting mixture, the jetting line was printed thicker or thinner and the accuracy of the printout was degraded. In order to adjust the viscosity of the liquid activator, 10% of the VMA was used in 35% of sodium silicate solution and the viscosity of 200–400 cP was suitable to be sprayed from the nozzle. With this optimal mixture, a prototype of atypical decorative wall was printed, and the compressive strength was measured at about 7 MPa.

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Silica extraction from bauxite reaction residue and synthesis water glass

Green Processing and Synthesis ◽

10.1515/gps-2021-0028 ◽

2021 ◽

Vol 10 (1) ◽

pp. 268-283

Author(s):

Yunlong Zhao ◽

Yajie Zheng ◽

Hanbing He ◽

Zhaoming Sun ◽

An Li

Keyword(s):

Sodium Silicate ◽

Water Glass ◽

Sodium Silicate Solution ◽

Silicate Solution ◽

Hydrated Calcium Silicate ◽

Precipitated Silica ◽

Alumina Gel ◽

Silica Alumina ◽

Element Removal ◽

Hydrated Calcium

Abstract Bauxite reaction residue (BRR) produced from the poly-aluminum chloride (PAC) coagulant industry is a solid acidic waste that is harmful to environment. A low temperature synthesis route to convert the waste into water glass was reported. Silica dissolution process was systematically studied, including the thermodynamic analysis and the influence of calcium and aluminum on the leaching of amorphous silica. Simulation studies have shown that calcium and aluminum combine with silicon to form hydrated calcium silicate, silica–alumina gel, and zeolite, respectively, thereby hindering the leaching of silica. Maximizing the removal of calcium, aluminum, and chlorine can effectively improve the leaching of silicon in the subsequent process, and corresponding element removal rates are 42.81%, 44.15%, and 96.94%, respectively. The removed material is not randomly discarded and is reused to prepare PAC. The silica extraction rate reached 81.45% under optimal conditions (NaOH; 3 mol L−1, L S−1; 5/1, 75°C, 2 h), and sodium silicate modulus (nSiO2:nNa2O) is 1.11. The results indicated that a large amount of silica was existed in amorphous form. Precipitated silica was obtained by acidifying sodium silicate solution at optimal pH 7.0. Moreover, sodium silicate (1.11) further synthesizes sodium silicate (modulus 3.27) by adding precipitated silica at 75°C.

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A Study on a Green Route to Preparation of Silica Powders with Rice Husk Ash

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1010-1012.1015 ◽

2014 ◽

Vol 1010-1012 ◽

pp. 1015-1019

Author(s):

Ze Xin Yang ◽

Lin Dong ◽

Meng Wang ◽

Huan Li

Keyword(s):

Sodium Bicarbonate ◽

Sodium Silicate ◽

Rice Husk ◽

Rice Husk Ash ◽

Sodium Hydroxide Solution ◽

Sodium Silicate Solution ◽

Silicate Solution ◽

Raw Material ◽

Transmission Electron ◽

Thermal Analyzer

The main purpose of this article is to develop an environmentally friendly and economically effective process to produce silica from rice husk ash. Sodium silicate solution was prepared by the reaction of rice husk ash and sodium hydroxide solution, and then the sodium silicate solution was used as the raw material for the preparation of silica with sodium bicarbonate. During the reaction, the by-product can be passed into CO2 to prepare sodium bicarbonate what can be reutilized. Experimental route achieved resource recycling and environment-friendly, low energy consumption, zero emissions and so on. Meanwhile the microstructures of the silica powders were characterized by Transmission electron microscope (TEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) and Thermo gravimetric/Differential thermal analyzer (TG-DTA).The purity of silicon was up to 99.43% and the particle size was 200-300nm.

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