scholarly journals Effects of suspension dispersity and concentration on its flocculation efficiency in static and dynamic flocculators

2019 ◽  
Vol 1 (1) ◽  
Author(s):  
Nickolaj Nikolayevich Rulyov ◽  
Oksana Kravtchenko ◽  
Fernando Concha
Keyword(s):  
Calcium Carbonate ◽  
Shear Rate ◽  
Silicon Dioxide ◽  
Dissolution Rate ◽  
Concentration Effect ◽  
Adhesion Forces ◽  
Suspension Concentration ◽  
Viscous Forces ◽  
Flocculation Efficiency ◽  
Dioxide Suspension

Flocculation presents one of the most effective methods for enhancing separation of both anthropogenic and natural suspensions by sedimentation, filtration and flotation techniques.The flocculation effectiveness much depends on the medium shear rate in a flocculator. The objective of this research comprises the study how the suspension dispersity and concentration effect the efficiency of its flocculation in a static tubular flocculator and in a dynamic Couette flocculator. The studies used aqueous suspensions of ultra-fine calcium carbonate (<7 μm) and fine silica (<90 μm) as objects. It was established that treatment of ultra-fine calcium carbonate suspension in a static flocculator produced in the range 400-450 s-1 a pronounced primary maximum in the dependence "flocculation efficiency/shear rate". The increase of the suspension concentration to 70 g/l and above resulted in a small secondary maximum of the flocculation efficiency in the region of around 950 s-1. This can be due to a higher dissolution rate of flocculant and a corresponding increase of particles adhesion forces in flocs, which counteract viscous forces destroying them. In silicon dioxide suspension treatment, the primary and secondary peaks occur at both small and high suspension concentrations, but in a latter case, they are by far more pronounced and comparable in magnitude.

Evaluation of a New Barium Sulfate Dissolver and the Effect of the Presence of Calcium Carbonate in the Dissolution Rate

2019 ◽  
Author(s):  
Jamal AlAamri ◽  
Mohammad AlDahlan ◽  
Fares M. Al-Otaibi ◽  
Abdulaziz Al-Ghamdi
Keyword(s):  
Calcium Carbonate ◽  
Dissolution Rate ◽  
Barium Sulfate

Study on the Reduction of Ferrous Compounds Disseminated in Fayalite, Vitreous and Magnetite in Dumped Copper Slag by Means of Carbonthermic Method

2011 ◽  
Vol 233-235 ◽  
pp. 684-688 ◽  
Author(s):  
Ya Long Liao ◽  
Xi Juan Chai ◽  
Jiang Tao Li ◽  
Fu Chang Xu ◽  
Dong Bo Li
Keyword(s):  
Calcium Carbonate ◽  
Silicon Dioxide ◽  
Reaction Temperature ◽  
Reduction Process ◽  
Copper Slag ◽  
Oxygen Anion ◽  
Positive Ion ◽  
Silicon Oxygen

Carbonthermic method was adopted to reduce the iron in the form of fayalite in copper slag to metal iron in this study. The reduction was undertaken under the conditions of roasting reduction at 1423 K for 4 h with specified parameters that the ratio of copper slag versus anthracite was 2∶1, and that the ratio of calcium carbonate to silicon dioxide was 1.43∶1. It was demonstrated that the metallization efficiency of iron could reach 88.26%. Moreover it was showed that the reduction process of fayalite by carbon could be routed as: Fe2SiO4(or 2FeO·SiO2)→ FeO + 2CaO·SiO2→ Fe. In addition it was proved that the combination ability between calcium positive ion and silicon oxygen anion was bigger than that between iron positive ion and silicon oxygen anion. As a result，SiO2 compacted in fayalite could decompose easily and could combine with CaO at the reaction temperature, therefore FeO could exist with a form of freedom state which could be reduce easily by carbon or monocarbon produced in carbonthermic method.

Influence of Solution Volume on the Dissolution Rate of Silicon Dioxide in Hydrofluoric Acid

ChemPhysChem ◽  
2014 ◽  
Vol 16 (2) ◽  
pp. 370-376 ◽  
Author(s):  
Boris Shvartsev ◽  
Danny Gelman ◽  
Ilia Komissarov ◽  
Alon Epshtein ◽  
David Starosvetsky ◽  
...  
Keyword(s):  
Silicon Dioxide ◽  
Dissolution Rate ◽  
Hydrofluoric Acid ◽  
Solution Volume

Manufacture Process of Light Calcium Carbonate from Limestone

2007 ◽  
Vol 336-338 ◽  
pp. 1843-1845
Author(s):  
Qi Wang ◽  
Min Fang Han ◽  
Jun Wei Wang
Keyword(s):  
Particle Size ◽  
Calcium Carbonate ◽  
Silicon Dioxide ◽  
Xrd Analysis ◽  
Hebei Province ◽  
Sphere Size ◽  
Comprehensive Properties ◽  
Manufacture Process

This process and parameters of fabricating light calcium carbonate from limestone were discussed in the paper. Raw limestone in experiment comes from Luquan city, Hebei province. The results of chemistry and XRD analysis indicate that ingredient of this limestone is mainly calcium carbonate, dolomite, silicon dioxide, which takes 83.81%, 11.03% and 1.67% separately, and a few of other impurities. The process includes calcinations, assimilation, carbonation, drying and others. It was ascertainable that the time of calcinations exceeded 5 hours at 850~ 950 and loss of calcinations was 42%. The time of assimilation was around 25 minutes at 70~90The time of carbonation was about 30 minutes at 50~90, and the airflow was about 160L/min and PH of latex after carbonation was 7.2~7.4. The light calcium carbonate product was obtained in experiment, whose fine sphere size was about 10 nanometer, with the agglomeration particle size 2~3μm. The degree of white improved from 42 to 76. As a result, the comprehensive properties of the produce were improved consumedly.

scholarly journals Evaluating the effect of the porous and non-porous colloidal silicon dioxide as a stabilizer on amorphous solid dispersion

2020 ◽  
Vol 10 (5) ◽  
pp. 255-263
Author(s):  
Smruti P. Chaudhari ◽  
Mittal Bhadiyadra ◽  
Rutesh H. Dave
Keyword(s):  
Silicon Dioxide ◽  
Dissolution Rate ◽  
Solid Dispersion ◽  
Water Solubility ◽  
High Surface ◽  
Amorphous Solid ◽  
Energy System ◽  
High Energy ◽  
Amorphous Solid Dispersion ◽  
The Stability

Advancement in the discovery of drugs has led to many highly lipophilic compounds with very low water solubility. Amorphous solid dispersion is one of the emerging technologies to increase the solubility of these drugs. The stability of these systems is critical since the high energy system tends to recrystallize, which negates the benefits of these systems. In this paper, we are evaluating the use of colloidal silicon dioxide as a potential stabilizer to stabilize the amorphous solid dispersions. Two types of colloidal silicon dioxide are used: porous colloidal silicon dioxide -Syloid 244 Fp and nonporous fumed silica – Aerosil 200. These silicon dioxides have a high surface area. Two methods of incorporation are used to incorporate silicon dioxide into the solid dispersion. The spray drying method is used to make amorphous solid dispersion. It was found that porous silicon dioxide is better to increase stability as well as increasing dissolution rate and % release of the drug. The addition of silicon dioxide internally to the dispersion increases the dissolution rate, and the addition of silicon dioxide externally increases the stability of the solid dispersion. Keywords: colloidal silicon dioxide, stabilizer, amorphous solid dispersion, low water solubility

scholarly journals THE INFLUENCE OF SOLAR MODULES SOILING ON THEIR ENERGY EFFICIENCY

2019 ◽  
Vol 10 (2) ◽  
Author(s):  
Ivana Radonjić ◽  
Tomislav Pavlović ◽  
Dragoljub Mirjanić ◽  
Darko Divnić
Keyword(s):  
Energy Efficiency ◽  
Calcium Carbonate ◽  
Solar Energy ◽  
Silicon Dioxide ◽  
Fossil Fuels ◽  
The World ◽  
The Republic ◽  
And Mathematics ◽  
Organic Minerals ◽  
Academy Of Sciences

This paper deals with the influence of solar modules soiling on their energy efficiency. Soiling is the term used to describe the deposition of dust on solar modules. Dust, most often contains organic minerals and particles which result from the burning of fossil fuels, etc. In research studies investigating the influence of dust on the solar modules efficiency in the world, in the Solar Energy Laboratory at the Faculty of Sciences and Mathematics in Nis, and in the Solar Energy Laboratory at the Academy of Sciences and Arts of the Republic of Srpska, it was concluded that all types of dust negatively affect the energy efficiency of solar modules, with ash, limestone (calcium carbonate), red soil and sand (silicon dioxide) having the greatest impact.

scholarly journals ABRASIVOS: UMA ANÁLISE DE DENTIFRÍCIOS COMERCIALIZADOS EM SALVADOR

2015 ◽  
Vol 5 (3) ◽  
Author(s):  
Lydia De Brito Santos ◽  
Ana Carla Ferreira Rios ◽  
Viviane Maia Barreto Oliveira ◽  
Sônia Cristina Freitas Lemos Lopes ◽  
Taiana Silva Dantas
Keyword(s):  
Titanium Dioxide ◽  
Calcium Carbonate ◽  
Aluminum Oxide ◽  
Sodium Bicarbonate ◽  
Silicon Dioxide ◽  
Color Change ◽  
Tooth Surface ◽  
The Public ◽  
The City

Most toothpastes sold in Brazil contains abrasive composition with the function of preventing the formation of spots or pigmented film and burnish the tooth surface, however, the indiscriminate use of abrasives has generated discussion regarding the effects of this component. Objective: To evaluate dentifrices sold in the city of Salvador as to its commercial presentation, regarding the inormation contained in the packages related to abrasives, in order to verify if guidelines are offered to the public to assist them in choosing those products and to the professionals when it comes to the guiding elements of the prescription. Methodology: We have analyzed 45 packages of toothpaste, randomly purchased from supermarkets in Salvador, for two years. We have observed the following: component that guides the classification of toothpaste, type and concentration of abrasive and instructions with respect to the degree of abrasiveness. Results: All trademarks contained abrasive analyzed singly or in combination; eight types of abrasives have been found: Calcium Carbonate (27%), Silica (26%), Sodium Bicarbonate, Silicon Dioxide, Titanium Dioxide, trisodium phosphate, aluminum oxide and sodium silicate. Manufacturers have associated to the dentifrices naturals extracts with the purpose to prevent the dental color change without tooth and gengival aggression caused by abrasives associations. Conclusion: Lack of guidance on packaging about the level of abrasiveness of toothpaste that can guide patients and professionals to its rational use.

scholarly journals Effect of Nano-additive on the Bonding Strength and Formaldehyde Emission of the Plywood Adhesive during Manufacturing of Wood Based Panel Products

2020 ◽  
Vol 10 (2) ◽  
pp. 158-161
Author(s):  
S.C. Sahoo ◽  
Amitava Sil ◽  
Dharm Pal
Keyword(s):  
Mechanical Properties ◽  
Shear Strength ◽  
Calcium Carbonate ◽  
Silicon Dioxide ◽  
Formaldehyde Emission ◽  
Adhesive Properties ◽  
Nano Technology ◽  
Panel Products ◽  
Amino Resin ◽  
Nano Silicon

Nano science and nano technology provides numerous opportunities for enhancing the properties of wood based panel products. In this study an extender was made using nano silicon dioxide ( Sio2), nano calcium carbonate( CaCo3) with some specialty chemicals at a certain reciprocal proportion. Efficacy study was carried out with both phenolic and amino resin in terms of rheological and formaldehyde emission test using reinforcement of nano additive as extender at different concentration level. The plywood panels has been tested as per IS: 1734-1983 for mechanical properties. The rheological and adhesive properties has been tested as per IS 848: 2006. The test data reveals that enhancement of rheological, bonding and mechanical properties have been achieved after reinforcement of synthetic resin. The increase in the percentage of nano-additive caused an increase of viscosity, glue shear strength and minimizing the formaldehyde emission than using individual nano silicon dioxide ( Sio2), nano calcium carbonate( CaCO3) instead of the extender made by combination of above. Using nano additive extender at 5%, there is an increase in glue shear strength in the glue line and enhanced rheological properties in amino resin based adhesive was observed.

scholarly journals Optimization of the temperature for the production of synthetic wollastonite based on rice husk

2020 ◽  
Vol 63 (8) ◽  
pp. 18-23
Author(s):  
Elena M. Gotlib ◽  
◽  
Ilya D. Tverdov ◽  
Ekaterina S. Yamaleeva ◽  
Thi Nha Phuong Ha ◽  
...  
Keyword(s):  
Calcium Carbonate ◽  
Silicon Dioxide ◽  
Rice Husk ◽  
Raw Materials ◽  
Amorphous State ◽  
Synthesis Temperature ◽  
Polymer Materials ◽  
Synthetic Wollastonite ◽  
Similar Content ◽  
Natural And Synthetic

Every year around the world, as a result of rice threshing, about 600 million tons of rice husk waste are generated. They pollute the environment, since rice husks do not disintegrate in the ground, due to the presence of silicon dioxide in its composition. Silicon dioxide from rice husk ash differs from other known types of silicon-containing raw materials in that it is in an amorphous state, contains less metal impurities and is chemically more active. At the same time, this amorphous silica can be effectively used in combination with limestone for the synthesis of promising types of fillers for polymer materials, in particular, wollastonite. Based on the results of X-ray analysis, the phase composition of the synthesized filler samples was determined. It was shown that synthetic wollastonite, regardless of the synthesis temperature and the ratio of silicon dioxide and calcium carbonate in its composition, contains mainly β-wollastonite and larnite as impurities. A higher content of β-wollastonite in the composition of the synthesized filler samples is achieved at temperatures of their preparation in the range from 800 to 900 °C. At the same time, in the case of wollastonite with a ratio of silicon dioxide and calcium carbonate 1:1, the synthesis temperature has a greater effect on its composition. Filling epoxy compositions, both natural and synthetic wollastonite, significantly increases their wear resistance. This effect is associated with the anisodiametric shape of the filler particles and is approximately the same when using natural and synthetic wollastonite, with a similar content of β-wollastonite in their composition.

Rheological Behavior of Highly Filled EPDM Compounds with Calcium Carbonate, Carbon Black, Silica and Zinc Oxide

1996 ◽  
Vol 69 (4) ◽  
pp. 628-636 ◽  
Author(s):  
Li Li Li ◽  
James L. White
Keyword(s):  
Particle Size ◽  
Zinc Oxide ◽  
Calcium Carbonate ◽  
Shear Rate ◽  
Carbon Black ◽  
Shear Viscosity ◽  
Volume Fraction ◽  
Carbonate Carbon ◽  
Yield Value ◽  
Yield Values

Abstract The shear viscosity, creep and constant shear rate transients have been measured for 0.20 volume fraction compounds of an EPDM with calcium carbonate, carbon black, silica and zinc oxide of similar particle size at 100°C. Measurements have been made in a creep sandwich instrument, pressurized rotational rheometer and a capillary rheometer and cover nine decades of shear rate. All of the compounds exhibit enhanced viscosities and yield values; i.e. there are stresses below which there is no flow. The greatest yield values and increased viscosities are with the compounds with calcium carbonate and zinc oxide. More extensive studies were made with the EPDM-calcium carbonate system, where it was shown that, increasing particle size reduces shear viscosity and yield values. Further, surface treating calcium carbonate with stearic acid signifcantly reduces the shear viscosity and yield value of the corresponding EPDM compound.

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