Tetraethoxy orthosilicate (TEOS) was used not only as a precursor of silica, but also as an agent which reinforces the skeleton of silica-gel to prepare an aerogel and resultant silica and silica-alumina with large pore size and pore volume. In this gel skeletal reinforcement, the strength of silica aerogel skeleton was enhanced by aging with …
Different separation technologies used to remove silica and alumina from low-grade iron ores were reviewed. The major concentration methods that may be applied to upgrade …
1-The content of silica or alumina before high gradient magnetic (%); n ... It is adverse for the separation of iron and alumina because of the mutual dissemination. A small amount of kaolinite adheres on the surface of massive limonite and forms bars with 20 m in thickness so it is easy to be removed in the
Here we report immobilization of glucose oxidase (GOx) on magnetic silica (Fe 3 O 4-SiO 2) and alumina (Fe 3 O 4-Al 2 O 3) functionalized with amino groups using glutaraldehyde as a linker.Magnetic support based biocatalysts demonstrate high catalytic activity in d-glucose oxidation to D-gluconic acid at pH 5-7.5 and temperature of 30-50 °C with the …
Polyimide networks are key in the development of stable, resilient, and efficient membranes for separation applications under demanding conditions. To this aim, the controlled design of the network's nanostructure and its properties are needed. However, such control remains a challenge with currently available synthesis methods. Here, we present a …
The utilization of coal fly ash has been of great concern in recent years due to the growing awareness of waste recycling and environmental protection. Alumina recycling from coal fly ash is a good path to realize the state-of-the-art utilization of coal fly ash. The present work proposes a novel strategy for recovering alumina and producing …
The applications of silica-aluminas in industrial catalytic processes are briefly reviewed. The literature data on the surface chemistry and structural chemistry of …
From the discussion in Section 1, alumina production from by-products of HAC is infeasible by directly using Bayer process due to the low A/S (~1.0); therefore, the key issue of alkali extraction of alumina is an efficient separation of alumina and silica in …
The deep understanding of the effects of the introduction of alumina in silica aerogels is the main goal of this review. In this overview, we discuss the sol-gel process …
Red mud (RM) is a solid waste discharged in the production of alumina from bauxite ores [].In general, about 0.8–1.5 tons of RM is generated from each tons of alumina production by Bayer process, and 1.5–2.5 tons of RM is discharged from the sintering or combined process. [] By 2018, the amount of cumulative RM had reached 4 billion tons …
The filtrates after separation were analyzed in Figure 6, in which the concentrations of alumina, silica and Na 2 O in the filtrates decreased very rapidly with the addition of concentrated H 2 SO 4, for …
3.1 Influence of Various Factors on the Alumina Materials 3.1.1 Initial Concentration of Solution. In the preparation of high-purity mesoporous γ-Al 2 O 3, the initial concentration of NaAl(OH) 4 solution significantly influences the content and removal rate of impurity in the alumina powder. As shown in Table 2 and Fig. 1, an increase in …
Afterwards, low-temperature alkaline leaching and Bayer digestion extracted 87% of silica and 89% of alumina, respectively. However, the poor separation effect of Si and Al is attributed to the ...
Carbon-carbon double bonds contribute somewhat more to compound adsorption on alumina as compared to silica gel, and hence compounds with unsaturation are generally better separated on Alumina than on other polar adsorbents such as silica gel. Alumina manufactured is of three types based on the pH ranges – acid, neutral and basic.
1. Introduction1.1. Silica membranes for hydrogen separation. Hydrogen permeable and selective membranes are potentially among the most important inorganic membranes in the gas separation field due to the importance of hydrogen as an industrial feedstock for the production of fuels and many chemicals [1], [2].The membranes have …
Silica or alumina. Pasteur pipette. Method: Fill the column about one third with solvent (Fig. 6, step B). In a beaker, measure out the required amount of silica or alumina. In a separate flask or beaker, measure solvent approximately one and a half times the volume of silica. Add the silica to the solvent, a little at a time, while swirling.
After magnetic separation, the alumina content, silica content, and the mass ratio of alumina/silica in the non-magnetic part of the separation product was 80.36 wt%, 6.49 wt%, and 12.38 ...
The combustion process of coal gangue and the subsequent separation of alumina and silica by alkaline leaching of the simulated CFB slag were investigated. The results show that, in the combustion process, kaolinite in coal gangue firstly converts into meta-kaolinite at 600-900 °C due to dehydroxylation, and then the meta-kaolinite splits …
Wu et al. synthesized alumina-silica with an enhanced mesoporosity and acidity by the sol-gel method accompanied in the presence of C 16 EO 10 acting as ... Silica-alumina catalyst with bimodal pore structure prepared by phase separation in sol-gel process. J Catal, 200 (2001), pp. 197-202, 10.1006/jcat.2001.3196. View PDF View …
The ferrous fractions can be recovered by a simple magnetic separation method, while alumina and silica can be extracted by chemical or biological approaches. Alumina extraction is possible using both alkali- and acid-based methods, while silica is extracted by strong alkali, such as NaOH. Chemical extraction has a higher yield than the ...
Alumina Silica Carbon Porous polymers Porous polymers Silica Porous polymers Select Perm. Gases Select Low Sulfur Porous polymers Silica Lowox OxyPLOT 18 July 31, 2014 . ... • Poor C4 isomer separation Alumina preferred • Not sensitive to moisture • Good choice for solvents and CFCs 19 July 31, 2014 .
Efficient removal of silica is the key to alumina extraction from coal fly ash (CFA) by the Bayer process, due to the easy formation of sodium aluminosilicate hydrates during alkaline digestion. Considering the main mineral of well-crystallized mullite in CFA, mechanical activation was used in this work to improve the silica removal during …
The separation of alumina and silica in clinker was carried out by alkaline leaching in 160 g/L NaOH solution with solid/liquid of 5 g/50 mL at 110 °C for 180 min. Fig. 8 shows that the silica leaching ratio is about 95% and nearly unchanged when treating the clinker of RCG-800 °C and RCG-900 °C, and the corresponding A/S in the leached ...
In this paper, a technique for comprehensive extraction of silica and alumina from circulating fluidized bed-based CFA is presented. The method involves reduction …
A thin layer (30–40nm) of a dual-element silica–alumina composition was deposited on a porous alumina support by chemical vapor deposition (CVD) in an inert atmosphere at high temperature.
The ferrous fractions can be recovered by a simple magnetic separation method, while alumina and silica can be extracted by chemical or biological approaches. Alumina extraction is possible using both alkali- and acid-based methods, while silica is extracted by strong alkali, such as NaOH. Chemical extraction has a higher yield than …
In this paper, we verify the separation effect of alumina and silica in CFB-derived coal fly ash by hematite involved roasting-alkaline leaching-Bayer digestion. The …
Also, it is worth mentioning that gases permeability tendency for the modified alumina support membrane, have changed from H 2 >CH 4 >CO 2 > CO to H 2 >CO 2 >CO > CH 4 for silica-zirconia CVD coated membranes.This phenomenon is in good agreement with the molecular size of the gases (H 2 = 0.289 nm, CO 2 = 0.33 nm, CO = …
Elaboration from clay (kaolin, mixtures of clay and alumina): mullite is obtained by reaction between silica and alumina present in the clay. The firing temperature ranging between 1200 and 1400 °C. Elaboration from sillimanite minerals and bauxite: This type of refractory is characterized by its high refractoriness, good mechanical strength ...
In this work a water vapor-permselective alumina–silica composite membrane reactor is proposed to overcome the thermodynamic equilibrium limitations and increasing catalyst activity. A steady state heterogeneous model is developed to simulate the proposed configuration. ... Simultaneous occurrence of reaction and separation …
DOI: 10.1016/j.cej.2024.148788 Corpus ID: 266988662; Silica-alumina zeolite adsorbents for oxygen generation via pressure swing adsorption: Mechanisms and challenge @article{Yu2024SilicaaluminaZA, title={Silica-alumina zeolite adsorbents for oxygen generation via pressure swing adsorption: Mechanisms and challenge}, author={Qingjun …
