The arrangement of fractal clusters dependent on the pH value in silica gels from sodium silicate solutions

2001 ◽  
Vol 296 (1-2) ◽  
pp. 81-87 ◽  
Author(s):  
B Knoblich ◽  
Th Gerber
Author(s):  
Aghiles Hammas ◽  
Gisèle Laure Lecomte-Nana ◽  
Nadjet Azril ◽  
Imane Daou ◽  
Claire Peyratout ◽  
...  

The present study aimed at investigating the influence of the concentration of sodium silicate and sodium hexametaphosphate on the dispersion of an aqueous kaolinitic clay slurry regarding further use for the tape casting process. The zeta potential of the kaolinitic clay slurry matched the requirements for tape casting. The addition of magnesite in the kaolinitic slurries tended to increase the zeta potential towards the required limit values. Despite, the further addition of surfactants allowed improving the zeta potential in agreement with the tape casting conditions. Accordingly, the rheological behavior, under continuous and oscillatory flow conditions, of various mixtures of magnesite and a kaolinitic clay was studied. Regarding the pH and the zeta potential measurements, the E–F attraction prevailed at low pH value, and F–F or E–E attraction was predominant at high pH value. All slurries exhibited a shear thinning behavior, which was well-correlated by Herschel–Bulkley model. It appeared that the best stability for the kaolinitic clay slurries was obtained while using 0.4 mass% and 1.2 mass% of sodium hexametaphosphate and sodium silicate respectively. An increase in the magnesite concentration above 6 mass% led to a complex behavior with low cohesion energy due to the occurrence of soluble complexes.


2015 ◽  
Vol 814 ◽  
pp. 220-229
Author(s):  
Hong Xu Zhang ◽  
Yu Jie Zhao ◽  
Jia Zhuang ◽  
Hai Yang Qin ◽  
Han Ling Zhang

With an analysis on the structure of water-soluble sodium silicate and its polymerization, it was found that the poor stability of silicate drilling fluids lies in the relevance between the inherent nature and the pH value of sodium silicate. The modification of water-soluble sodium silicate in this paper was to improve its stability and keep the inhibitive property simultaneously. The a-olefin sulfonate (AOS) was employed as the modifer agent acted on the water-soluble sodium silicate monomer and oligomers. Furthermore, the modification mechanism was discussed through FTIR, Laser particle size, Zeta potential and SEM. A stable sodium silicate drilling fluids with better inhibitive property was obtained by the comparison of modified sodium silicate and unmodified ones.


Minerals ◽  
2019 ◽  
Vol 9 (12) ◽  
pp. 757 ◽  
Author(s):  
Aghiles Hammas ◽  
Gisèle Lecomte-Nana ◽  
Nadjet Azril ◽  
Imane Daou ◽  
Claire Peyratout ◽  
...  

The present study aimed at investigating the influence of the concentration of sodium silicate and sodium hexametaphosphate on the dispersion of an aqueous kaolinitic clay slurry regarding further use for the tape casting process. The zeta potential of the kaolinitic clay slurry matched the requirements for tape casting. The addition of magnesite in the kaolinitic slurries tended to increase the zeta potential towards the required limit values. Despite this, the further addition of surfactants allowed improving the zeta potential in agreement with the tape casting conditions. Accordingly, the rheological behavior, under continuous and oscillatory flow conditions, of various mixtures of magnesite and a kaolinitic clay was studied. Regarding the pH and the zeta potential measurements, the E–F attraction prevailed at low pH value, and F–F or E–E attraction was predominant at high pH value. All slurries exhibited a shear thinning behavior, which was well-correlated by the Herschel–Bulkley model. It appeared that the best stability for the kaolinitic clay slurries was obtained while using 0.4 mass% and 1.2 mass% of sodium hexametaphosphate and sodium silicate, respectively. An increase in the magnesite concentration above 6 mass% led to a complex behavior with low cohesion energy due to the occurrence of soluble complexes.


2020 ◽  
Vol 9 (5) ◽  
pp. 10157-10165
Author(s):  
Elham Katoueizadeh ◽  
Maryam Rasouli ◽  
Seyed Mojtaba Zebarjad

Author(s):  
Takashi Saeki ◽  
Saori Kikuchi ◽  
Masahiro Ishida ◽  
Aya Kaide

Silica sols were produced continuously by using a Y-shaped reactor. Diluted sodium silicate and sulfuric acid were forced to collide with each other at the intersection of the reactor. The produced silica sols gradually increase in the viscosity and finally form silica gels. In this study, the gelation process of silica sols was considered by rheological measurements. The onset time of gelling was strongly affected by both the concentration of SiO2 and the excessive rate of sulfuric acid. Also, the gelation time can be controlled by the addition of appropriate amount of water of sulfuric acid solution.


Author(s):  
Yonghua Lu ◽  
Weiwei Gao ◽  
Fang Xu ◽  
Guangxian Zhang ◽  
Fengxiu Zhang

<p>In order to improve the catalytic degradation property of α-FeOOH, α-FeOOH was doped with sodium silicate. The α-FeOOH doped with silicon was used as catalyst to catalyze the degradation of methyl orange. The XRD spectra showed that the crystalline phase of α-FeOOH doped with silicon was same as that of α-FeOOH; The catalytic degradation property of α-FeOOH doped with silicon was 21.7% higher than that of α-FeOOH; The results showed that catalytic degradation of methyl orange was almost degraded thoroughly at the conditions that the concentration of α-FeOOH doped with silicon in the solution was 0.73 g/L, the concentration of H<sub>2</sub>O<sub>2</sub> was 0.231 mmol/L. The pH value was between 2 and 3, and the degradation reaction was carried out at 60 <sup>o</sup>C for at least 20 min. Copyright © 2016 BCREC GROUP. All rights reserved </p><p><em>Received: 5<sup>th</sup> November 2015; Revised: 9<sup>th</sup> January 2016; Accepted: 13<sup>rd</sup> January 2016</em></p><p><strong>How to Cite</strong>: Lu, Y., Gao, W., Xu, F., Zhang, G., Zhang, F. (2016). The Catalytic Degradation Performance of α-FeOOH Doped with Silicon on Methyl Orange.<em> Bulletin of Chemical Reaction Engineering &amp; Catalysis</em>, 11 (1): 120-124. (doi:10.9767/bcrec.11.1.434.120-124)</p><p><strong>Permalink/DOI</strong>: <a href="http://dx.doi.org/10.9767/bcrec.11.1.434.120-124">http://dx.doi.org/10.9767/bcrec.11.1.434.120-124</a></p><p> </p>


2011 ◽  
Vol 361-363 ◽  
pp. 343-345
Author(s):  
Lin Li ◽  
Xian Jun Lu ◽  
Jun Qiu ◽  
Peng Li

This paper adopts sedimentation experiment to study the sedimentation process of one molybdenum ore flotation tailings and to investigate the effects of lime and sodium silicate on sedimentation performance of tailings. Through the experiment on sedimentation speed and compressive layer density, it reveals the sedimentation performance rules of these tailings. Meanwhile, it explores the effects of lime and sodium silicate on sedimentation dry beach of tailings. The research shows that: lime could effectively ameliorate the non-easy sedimentation caused by sodium silicate; when the dosage of sodium silicate is 300~800g/t, the sedimentation performance can reach the best reasonable pH value 9-10. Besides, the study also indicates that both sodium silicate and lime are unfavorable to form sedimentation dry beach by tailings of concentrating mill.


Materials ◽  
2020 ◽  
Vol 13 (18) ◽  
pp. 4202
Author(s):  
Stephan Partschefeld ◽  
Torben Wiegand ◽  
Frank Bellmann ◽  
Andrea Osburg

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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