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Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula SiO 2, commonly found in nature as quartz. [5] [6] In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant families of materials, existing as a compound of several minerals and as a
Precipitated silica is an amorphous form of silica (silicon dioxide, SiO 2); it is a white, powdery material. Precipitated silica is produced by precipitation from a solution containing silicate salts. The three main classes of amorphous silica are pyrogenic silica, precipitated silica and silica gel.
[4] [5] [6] Dehydrating the latter yields a hard translucent form of silica with atomic-scale pores, called silica gel, which is widely used as water absorbent and drying agent. Silica dissolves very sparingly in water [citation needed] and is present in seawater at concentrations below 100 parts per million. In such dilute solutions, silica is ...
These products are often called precipitated silica or silica sols. Hydrogen ions from the surface of colloidal silica tend to dissociate in aqueous solution, yielding a high negative charge. Substitution of some of the Si atoms by Al is known increase the negative colloidal charge, especially when it is evaluated at pH below the neutral point ...
The solubility of silica strongly depends on the temperature and pH value of the environment [3] where pH9 is the controlling value. [1] Under a condition of pH lower than 9, silica precipitates out of the fluid; when the pH value is above 9, silica becomes highly soluble. [3]
The tables below provides information on the variation of solubility of different substances (mostly inorganic compounds) in water with temperature, at one atmosphere pressure. Units of solubility are given in grams of substance per 100 millilitres of water (g/(100 mL)), unless shown otherwise. The substances are listed in alphabetical order.
Calcium silicate neutralizes active acidity in AMD systems by removing free hydrogen ions from the bulk solution, thereby increasing pH. As its silicate anion captures H + ions (raising the pH), it forms monosilicic acid (H 4 SiO 4), a neutral solute. Monosilicic acid remains in the bulk solution to play other important roles in correcting the ...
Sodium silicate solution is used as a fixative for hand dyeing with reactive dyes that require a high pH to react with the textile fiber. After the dye is applied to a cellulose-based fabric, such as cotton or rayon, or onto silk, it is allowed to dry, after which the sodium silicate is painted on to the dyed fabric, covered with plastic to ...