Big Chemical Encyclopedia

Chemical substances, components, reactions, process design ...

Articles Figures Tables About

Aluminium hydroxides, dehydration

To the second of the three test tubes add an excess of sodium hydroxide. (6) What occurred (The salt formed is that derived from a dehydrated aluminium hydroxide of the composition Al(OH)3 — HgO = HAIO2.) (7) Write an equation for the reaction. (8) As what kind of a compound does aluminium hydroxide act in this case (9) Write an expression of the kind used in Experiment 125 to show the equilibria involved in a suspension of aluminium hydroxide. (10) Explain with reference to this expression the actions of hydro-... [Pg.259]

Alumina. Alumina (aluminium oxide) (Figure 3.3) can be synthesised to the same degree of purity and specification as silica gel by a series of non-uniform dehydration processes of various crystalline modifications of aluminium hydroxide [51]. Furthermore, the reaction conditions can be adjusted to produce aluminium oxide with either an acidic, basic or neutral surface it can be used with or without a binder and the use in the latter form is more common than with silica. [Pg.54]

The chemistry of the acid aluminium phosphates and their hydrates is complicated. Thermal dehydration of the anhydrous salts leads to condensation and the formation of polyphosphates (5.123), (5.135). Dehydration of the crystalline hydrates can give rise to various mixtures of anhydrous acid phosphates, AIPO4 and amorphous material, depending on the conditions employed. Aluminium acid phosphates have isomorphous iron analogues with which they can form solid solutions. Acid phosphates of iron and aluminium are present in soils and are very much involved in the reactions which take place between soil and fertilisers (Chapter 12.2). Aluminium hydroxide/phos-phoric acid solutions with AI2O3/P2O5 = 1.0-1.5 will give extremely viscous fluids which can be dried down to amorphous solids. Such solids can then be re-dispersed in water to form viscous solutions which are stable under acid conditions. [Pg.209]

After milling, the ore is first broken down using an Al-containing NaOH solution which is seeded to precipitate aluminium hydroxide Al(OH)3. This is dehydrated at about 1100 °C according to 2Al(OH)3 —> AI2O3 -I-3H2O. [Pg.171]

An explanation of why both aluminium hydroxides foUow two dehydration routes is that bohmite is formed under hydrothermal conditions [82, 84]. x- and j-Aluminium oxides are the only products observed as first dehydration products of finely divided hydrargiUite and bayerite respectively. Coarser starting material yields bohmite and its decomposition products in both cases. Deboer and coworkers assume... [Pg.23]

Another known method of preparing disordered aluminium hydroxide is pulse thermal heating of aluminium hydroxide at relatively low temperatures [46]. Pulse heating can be carried out by different means in the flow of hot gas, with electron beam. Pulse heating in the flow of hot gas leads to a partial dehydration of the initial gibbsite. The degree of dehydration depends on the conditions of thermal treatment. In particular, under certain conditions the formation of completely X-ray amorphous product is possible, its composition being close to that of boehmite (AlOOH). [Pg.634]

Doyleite is a triclinic aluminium hydroxide mineral with composition Al(OH)3. It occurs as masses of soft white tabular crystals with pearly lustre which form from the weathering of aluminium-rich rocks in tropical climates. Hence, doyleite is often found in bauxites (. v.). Doyleite is closely related to another triclinic form of A1(0H)3, nordstrandite, and the monoclinic polymorphs, gibbsite and bayerite qq.v.), with which it may be found (Chao et al., 1985) it is also related to the orthorhombic dehydrated forms of AIO(OH), boehmite and diaspore qq.v.). Synthetic alu-minimn hydroxide Al(OH)3 is commonly encountered as a substrate for lake pigments. [Pg.142]

Methyl alcohol of very high purity can be obtained by fractional distillation using a column of 1-3 metres effective length and then refluxing with aluminium amalgam. It is then refluxed under a column packed with dehydrated copper sulphate, to remove ammonia. A sensitive test for acetone and formaldehyde is the addition of cone, mercuric cyanide solution, in 6N-sodium hydroxide. A white precipitate indicates ketone if it darkens on standing aldehyde is also present. (J. C. S., 127, 2552.)... [Pg.213]

Also the thermo-oxidative stability of the deactivated polymer is excellent. At the present time, hydroxides and partially dehydrated hydroxides of amphoteric metals, especially of aluminium, are applied as additives suppressing the flammability of polymers. [Pg.423]


See other pages where Aluminium hydroxides, dehydration is mentioned: [Pg.91]    [Pg.91]    [Pg.192]    [Pg.353]    [Pg.478]    [Pg.353]    [Pg.269]    [Pg.275]    [Pg.275]    [Pg.613]    [Pg.961]    [Pg.30]    [Pg.250]    [Pg.598]    [Pg.8]    [Pg.109]    [Pg.150]    [Pg.423]    [Pg.108]    [Pg.22]    [Pg.209]   


SEARCH



Aluminium hydroxid

Aluminium hydroxide

Dehydration, hydroxides

© 2024 chempedia.info