Instituto Tecnolgico Superior de Irapuato.

Career:

Engineering Materials.

Signature:

English level 6.

Teacher:

Monica Jazmn Contreras Partida.

Project:

Synthesis of alpha alumina - Al2O3,

by solution precipitation method.

Team:

Lezo Salazar David.

Mendoza Manrquez Adriana.

Date: Friday March 20, 2015

Introduction.

In the current technology of alumina, Al2O3, is one of the most used compounds.

Have multiple uses in industry: as an additive in the paper industry, toothpastes,

paints, coatings, industry rubber and polymers. The activated alumina is in use as

desiccators and in catalytic processes. In the electronic industry it uses in

equipments of accumulation and generation of electrical power and in the

manufacture of insulating porcelain. It is in use in addition in the production of

coverings of biomaterials.

The bauxite is the important more and abundant raw material for the powders of

alumina and the process Bayer the one that is in use with such an end. In order to

obtain an alumina of major purity, and with a size of particle and morphology

determined, they have developed a great variety of methods, being outlined between

them the rainfall from homogeneous solutions, and that of emulsions and the Sun -

emulsion - gel.

The predecessors of the cation of aluminum more used are the sulfate of aluminum,

Al2 (SO4)3, the alcoxides, Al (OC3H7)3, and the chloride of aluminum AlCl3. Though

the technologies that allow obtain the alumina, with different morphology and size of

particle are described knowing the beginning physicist - chemists involved in them.

Due to the fact that the methods of syntheses that allow the formation of a phase

occurred in the bosom of a watery solution are those of major industrial possibility.

Initial manufacture of almina. Marggraf isolated by the first time "almina" extracting

it from natural clay with sulphuric acid in 1754 and the word "almina" was coined

by the first time for the substance by Guyton de Morveau in 1761 [British Patent].

This was followed by the discovery of the rich land in almina near Them Baux

(Arles's region - A medieval kingdom of this one and south-east France) by Berthier

that it named bauxite. Production of almina began for the first time in 1860 in the

south of France across the Sainte-Claire Deville process that was consisting of

attacking the bauxite for the sodium carbonate followed by the rainfall of almina I

hydrate [Ganguli, D.; Chatterjee, M].

New natural forms of almina Though progresses have been done in the field of

manufacture of almina, his new natural forms were also to be an overdraft. Some

of these are A Corundum (overdraft in 1799), Dispore (1801), Gibbsite (1820), The

boehmite (1924), bayerite (1925), nordstrandite (1956). Gibbsite was the first form

of almina that replaces the use of alum in the industry of the paper and in the water

I process of treatment [Ray, J.; Chatterjee, M]

Problematic:

Alumina enough for students studying engineering materials to perform their tests

for characterization of metal samples for metallographic microscope.

Justification:

For alumina materials laboratory needed to perform mirror-polished metal parts, to

properly characterize and to observe well the different phases that presented by

each different type of metal.

The synthetic method is used for precipitation as it is the cheapest and fast for

alumina.

General Objective.

Synthesize and characterize alpha Al2O3 by means of precipitation and determine

the variables and how they affect the morphology and particle size.

Specific objective:

To Use to characterize the alumina obtained for the metals.

To Analyze Whether the precipitation method is the most feasible.

To obtain powder with the purest available.

Delimiter:

the delimitation of our project is given because the tools or instruments used for

preparation of the synthesis by the method of precipitation and select the optimal

reagents to carry out such precipitation as we can from the organic route or inorganic

route to study the art acid base and strict control of pH and temperature as they are

two very important factors in synthesizing alumina.

Theoretical framework

The advanced materials, particularly the advanced ceramics play an important

paper in the future of the economy of a country. The development and use of

advanced ceramics are revolutionizing the field of the science and technology, for

the dramatic changes that take place in the processing of the above mentioned

materials. The result of this promotes the improvement of existing products and the

birth of new technologies [Wang, L.; Lloyd]. The characteristics of a ceramic

component are influenced greatly by the characteristics of the precursor powder.

Between the most important it are the chemical purity, distribution of size of particle

and the way in which the powders conform to form a ceramic body. [Blendell, J.E.;

Bowen, H.K]

The almina is the chemical compound that takes place in major volume worldwide,

nowadays they exist on the market a great quantity of products that we use daily and

that help to do our more pleasant life. [Blendell, J.E.; Bowen, H.K].

The principal methods that are in use for the obtaining of to - alumine are: The

calcination of hydroxides of aluminium, transition of alminas, you go out of

aluminium and solidification of the mergers. The least common methods are: the

synthesis hidrotrmica to high pressure, transition phase - steam and oxidation of

the aluminium to high temperatures. The process Bayer is in use almost exclusively

for the extraction of almine of mineral bauxite. Approximately, 90 % of the

production is destined to the remaining obtaining of metallic aluminum and 10 %, to

the obtaining of other chemical products based on alumina [Blendell, J.E.; Bowen,

H.K].

By means of the process Bayer there takes place a great quantity of pollutant

residues. The presence of these pollutants, as well as the lack of this raw material

in certain countries, has led to the search of other minerals of aluminum and other

methods of processing to obtain alumina. Consequently the above mentioned

methods are the persons in charge in developing new routes of processing for the

obtaining of alumina of high quality [Blendell, J.E.; Bowen, H.K].

Alumina ceramic for use.

Minerals containing Alumina represent some 15 % of the earth's crust. Therefore it

is an abundant material and virtually inexhaustible commodity unlike many alloys

developed for special applications. The combination of high thermal conductivity,

high compression resistance and low thermal expansion in a good thermal shock

resistance. Why should alumina crucibles used in furnaces, tubes and thermocouple

sheaths.

Alumina also provides good electrical insulation at high temperatures, good wear

resistance and high hardness which makes it suitable for use in valves, deep

extraction tools , cutting tools , packaging sealants and bomb parts mechanical ,

cylinders, spheres in milling , shields , refractories, abrasives, cements , flame

retardants , adsorbents , adhesives and advanced ceramics is used in the nuclear

isolation and open reel magnetic media communication [ Matijevic , E. ].

Uses of high purity alumina.

A special application of the high purity alumina is the manufacture of tubes for

sodium vapor lamps. Obtaining these translucent ceramic goods would not be

possible without the commercial production of calcined high purity alumina [Bassett,

H., Goodwin, TH J].

Another important application of high purity calcined alumina is carried out in the

field of medicine. They are made of alumina ceramic bodies to replace bones and

joints, such as hip joints and dental implants. The success of the aluminas in this

field, the high mechanical strength is due to fine surface finish, high density and

purity that can be achieved with this material [Kato, E., Daimon, K., Nanbu, M.].

Sequences of the phases of the alumines.

Phase transitions of alumines.

It has been an overdraft that the almine can exist in a variety of structures, which

are reproduced and stable to certain range of temperature. The sequences of the

phase transitions, with approximate ranges of thermal stability, these sequences are

generally accepted, though still there is confusion on the identification of some

phases and existence of others. The factors that affect the temperature transition or

the phase sequence are: the material of item, the size of particle, the extension of

the disorder or activity of transformation, gases in the atmosphere of calcination,

speeds of warming, impurities and additives used to promote or to retard the growth

of the crystals [18].

Methods of Almina's extraction.

The general procedures, for extraction they include the following ones:

Alkaline Processes: Process Bayer.

Acid Processes: H2SO4, HCl, HNO3, H2SO3 and you work out acid alkaline

Processes in oven:

Use of you work out alkaline Na2CO3, CaCO3, mixes of sulfates, chlorides or

others you go out and agents reducers.

Process term Carbone: coal utilization like agent reducer.

Electrolytic Process: Separation of the almina of solutions of aluminates [19].

Precipitation.

This technique is widely used for preparing a variety of semiconductors, such as

ZnO. The method relies on the addition of a precipitating agent to the solution of

ions, so that an insoluble salt is formed continuously. The salt formed is filtered,

washed several times to remove some undesirable ions and subsequent calcination

generates the desired crystalline phase. The precipitating agent more followers by

being cheap and decompose at low temperature is urea, but may be some other

mind, such as ammonium bisulfite. Precipitation can be homogeneous or

coprecipitation [Gordon, L.; Salustsky, ML, Willard, HN].

Homogeneous precipitation in the preparation of ceramic

precursors.

From the viewpoint of the ceramic materials, the application of the homogeneous

precipitation of precursors in the preparation has the following advantages:

Materials are obtained with higher degree of homogeneity, reactivity and

sinterability.

Finer materials stoichiometry control and greater uniformity in the trace

additive dispersion is achieved.

Avoids contamination inherent to the operations of mixing and grinding

[Gordon, L.; Salustsky, ML, Willard, HN].

In this technique in the homogeneous precipitation is generated or added

continuously precipitating agent so that small solid cores that grow as time passes

are formed. The particle size can be controlled by controlling the feed rate of

generation or the precipitating agent. This method precipitates ions individually, one

immediately after the other, this causes segregation. To resolve this problem

coprecipitation is used, where all cations are precipitated simultaneously [Gordon,

L.; Salustsky, ML Willard, HN].

The precipitate is generated in the bulk solution by a slow reaction, instead of being

formed by direct addition of precipitating reagent [Gordon, L.; Salustsky, ML, Willard,

HN].

The homogeneous precipitation is based on the control of the nucleation and particle

growth by chemical generation of one of the reactants, so that the supersaturation

is maintained at a low level during the course of the precipitation. Thus, few nuclei

are produced in the beginning of the process. The particles are produced in the

solution at the same time and under identical conditions of the solution, therefore,

the generated particles have uniform size and shape. In contrast to the above , the

conventional precipitation generally produces powders with wide particle size

distribution and various morphologies because it is performed under conditions of

high saturation , where the nucleation and growth occur simultaneously [ Gordon ,

L. ; Salustsky , ML , Willard , HN ] .

The relationship between particle size and relative degree of supersaturation was

investigated by Weimarm, who established that the number of nuclei generated

during the precipitation is proportional to the relative supersaturation [Gordon, L.;

Salustsky, ML, Willard, HN].

= ( )

Where:

K = Constant.

S = solubility of the substance which precipitates.

Q = total concentration of the substance which precipitates.

If the relative supersaturation ( Q - S ) / S is high, during the precipitation a large

number of nuclei form , which cant increase a lot in size , because it has been very

little solute dissolved in excess, with respect to the solubility of the species

precipitated. Therefore, much of the product precipitated in the form of small particles

[Gordon, L.; Salustsky, ML, Willard, HN].

Moreover, if the relative supersaturation is small, a few cores, which may continue

to grow in size from the ions in the solution will be formed. Under these conditions,

a precipitate comprising large particles [; Salustsky, ML, Willard, HN Gordon, L.] is

obtained.

The most important conditions for a homogeneous precipitation are:

The reagents used must not react while adding to the system.

The precipitating reagent should be formed by a slow reaction, often by

hydrolysis [Gordon, L.; Salustsky, ML, Willard, HN].

In the most common procedures homogeneous precipitation, we resort to the

following reactions:

Deprotonation of a hydrated cation.

Controlled generation of precipitating anions.

decomposition of metal complexes [ Gordon , L. ; Salustsky , ML , Willard ,

HN ] .

Bibliographic references.

Alumina Chemicals: Science and Technology Handbook,

Hart, L.D. (ed), The American Ceramic Society, Inc., 1990.

British Patent 10, 093, 1887.

Ganguli, D.; Chatterjee, M. Ceramic Powder preparation:

A Handbook, Klwver Academic Publishers, 1997.

Willard, H.; Tang, N.K. J. Am. Chem. Soc., v. 59, p.1190-1196, 1937.

Nagai, H.; Hozazono, S.; Kato, A. Br. Ceram. Trans. J., v. 90, p. 44-48, 1991.

Sarikaya, Y.; Akin, M. Ceram. Int., v. 14, p. 239-244, 1988.

Ray, J.; Chatterjee, M.; Ganguli, D. J. Mater Sci. Lett, v. 12, p. 1755-1757,

1993.

Wang, L.; Lloyd, I.K. J. Am. Ceram. Soc., v. 74, p. 2934-2936, 1970.

Blendell, J.E.; Bowen, H.K.; Coble, R.L. Am. Ceram.Soc. Bull, v. 63, n. 6, p.

797-802, 1984.

Sacks, M.; Tseng, T.Y.; Lee, S.Y. Am. Ceram. Soc. Bull., v. 63, p. 301-310,

1981.

Nagai, H.; Oshima, Y.; Hirano, K.; Kato, A. Brit. Ceram. Trans, v. 92, p. 114-

119, 1993.

Matijevic, E. Chem. Mater., v. 5, p. 412-426, 1993.

Surface and Colloid Chemistry in advanced ceramics

Processing, Pugh, R.J.; Bergstrom, L. (ed), Surfactant

Science Series v. 51 Marcel Dekker, Inc., 1994.

Otterstedt, J.; Brandreth, D. Small particles Technology, PlenuPress 1998.

Johansson, G. Acta Chem. Scand., v. 14, n. 3, p. 771-773, 1960.

16. Bottero, J.Y.; Fiessinger, F. Nordic Pulp and Paper Res. J., n. 2, p. 81,

1989.

Bassett, H.; Goodwin, T.H. J. chem... Soc., p. 2239, 1949.

Gordon, L.; Salustsky, M.L.; Willard, H.N. precipitation from homogeneous

solution, Wiley, New York, 1959.

Kato, E.; Daimon, K.; Nanbu, M. J. Am. Ceram. Soc. v. 64, n. 8, 436-443,

1981.

Brace, R.; Matijevic, E. J. Inorg. Nucl. Chem., v. 35, p. 3691-3705, 1973.

Products for laboratory y aquaculture; Favela Pro Sinaloa, Mxico 2014 p. 1-

3.

Methodology:

Chemical reaction and balanced proposal:

Al2

(SO4)3 18H

2O + 6Na (OH)

(ac) 2 Al (OH)

3 + 3Na

2 SO

4 (ac) + 18H

2O

Calculation:

Stoichiometric

calculation Al2(SO4)3 18H2O 6Na(OH)(ac) 2 Al(OH)3 3Na2SO4(ac) 18H2O

number of mol

stoichiometric 1 mol 6 mol 2 mol 3 mol 18 mol

Stoichiometric

mass 666 g/mol 240 g/mol 156 g/mol 426 g/mol 324 g/mol

required mass 666 g 240 g 156 g 426 g 324 g

total of reactants

and products 906 g 906 g

Reaction product:

2 Al (OH) 3 Al2O3(s) + 3H2O (g)

Calculation:

Stoichiometric calculation 2 Al (OH) Al2O3(s) 3H2O(g)

number of

moles stoichiometric 2 mol 1 mol 3 mol

Stoichiometric mass 156 g/mol 102 g/mol 54 g/mol

Required mass 156 g 102 g 54 g

Total of reactants and

products 156 g 156 g

Process scheme

Step by step procedure.

1. Weigh 666 g of powder Al2 (SO4) 3 18H2O (s) Industrial grade.

2. Weigh 240 g of Na (OH) (aq) in aqueous solution that is equivalent to 60

mL.

3. Vacuum filtration of the solution of Al2 (SO4) 3 18H2O (s) distilled water.

4. The system to carry out the reaction was assembled.

5. Heating the aqueous solution of aluminum sulfate in water bath

octadecahidrate at a temperature of 60 C

6. Once it reaches 60 C the solution of Al2 (SO4) 3 18H2O solution of

sodium hydroxide is added dropwise.

7. To wash and to leak the obtained precipitate: 5 repetitions of wash with

250 mL of H2O (Revealed) to 25C.

8. To separate the precipitate washed in two parts:

1. The sample to dried to 25C.

2. The sample B dried to 100 C.

9. The sample to dried to 25C.

10. The sample B dried to 100 C.