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Catalytic Oxidations
Published in Martyn V. Twigg, Catalyst Handbook, 2018
The use of vanadium catalysts for the oxidation of sulphur dioxide was reported by de Haen in 1900, but the activity of his material was low. Commercial catalysts developed by BASF were introduced around 1920.378, 379 Many variations of this type of catalyst followed, in particular the “Seldon mass” over which a lengthy court case was fought in 1932,374, 378 and the Monsanto catalyst370 which eventually became the most widely used catalyst. The Seldon mass was based on a support produced by the addition of potassium silicate solution to kieselguhr, while the Monsanto catalyst was much simpler. Silica gel was precipitated from potassium silicate with hydrochloric acid in the presence of a solution of ammonium metavanadate and potassium hydroxide. The product was then dried, extruded and calcined.
p-Dioxins and Dibenzofurans in the Aquatic Environment
Published in B. K. Afghan, Alfred S. Y. Chau, Analysis of Trace Organics in the Aquatic Environment, 2017
The extract is passed through a series of silica based adsorbents and a carbon/glass fiber adsorbent. The CDD/CDF as well as PCB, PCN are retained on the carbon fiber and are recovered by reverse elution with toluene. The toluene extract is applied to two tandem columns containing cesium or potassium silicate with sulfuric acid/silica gel followed by alumina. Elution from these two columns provide the final fractionation of CDD/CDF from the other chlorine containing organics. This scheme has been applied to a variety of species of freshwater fish,117 snapping turtle fat, Baltic seal fat,200 aquatic soils,201 and soot from an office fire involving PCB.202
Effect of freeze-thaw on K-based Geopolymer Concrete (GPC) and Portland Cement Concrete (PCC)
Published in Alka Mahajan, B.A. Modi, Parul Patel, Technology Drivers: Engine for Growth, 2018
Fernanda Belforti, Peiman Azarsa, Rishi Gupta, Urmil Dave
The alkaline liquid used was a combination of Potassium hydroxide and Potassium silicate solution. Potassium hydroxide (KOH) in solid pellets form (85% pure) and purchased from Sigma-Aldrich was used. Potassium Silicate (K2SiO3) powder obtained from PQ Corporation (USA) supplier has been used. The ratio of SiO2/K2O is 1.62 and the amount of water is 14.8. Sand and coarse aggregates obtained from a quarry in British Columbia, Canada, have been used. Sand presented 2.685 Relative Dry Density, 1.42% Water absorption and coarse aggregates size of 10 mm presented 2.767 Relative Dry Density, and 0.954% Water absorption.
Renewable biofuel production from biomass: a review for biomass pelletization, characterization, and thermal conversion techniques
Published in International Journal of Green Energy, 2018
Manar Younis, Sabla Y. Alnouri, Belal J. Abu Tarboush, Mohammad N. Ahmad
Both silicate and lignin are considered the most popular binders in the pellet industry, can sequester metals, may be used dispersants, as well as in many other applications. Nevertheless, a recent study has reported some complementary applications for many lignin and silicate compounds, especially for calcium lignosulfonate (McDonald and Hamilton 2009). Calcium lignosulfonate may be found in both solid and liquid form (~50% solids). However, both forms of calcium lignosulfonate can be used with silicates. Even though potassium or lithium silicate may sometimes be used for particular applications, sodium silicate is the most used binder compared to other alkali silicates, due to its competitive price. When sodium silicate is considered undesirable for a certain application, potassium silicate is utilized. For example, potassium silicate was found suitable for welding rod applications and in acid-resistant cements (McDonald and Hamilton 2009). In addition, potassium silicate is currently under study as a potential binder in the fertilizer industry; increased solubility of potassium silicate can generally improve pellet strength.