Journal of Materials Science and Chemical Engineering, 2013, 1, 11-15
http://dx.doi.org/10.4236/msce.2013.15003 Published Online October 2013 (http://www.scirp.org/journal/msce)
Copyright © 2013 SciRes. MSCE
Influence of the Precipitating Reagents and Dispersants on
the Formation Nano-Aluminum Hydroxide
G. Sarsenbay1, L. A. Myltykbaeva2, R. A. Abdulwalyev1, B. M. Sukurov1
1Center of the Earth Sciences, Metallurgy and Benefication, JSC, Science and Education Ministry
of the Republic of Kazakhstan, Almaty, Kazakhstan
2National Science and Technology Holding “Parasat”, JSC, Science and Education Ministry
of the Republic of Kazakhstan, Astana, Kazakhstan
Email: mer-pa@mail.ru
Received July 2013
ABSTRACT
The influence of the precipitating reagents and dispersants on the formation of nano-aluminum hydroxide from sodium
aluminate solution by chemical precipitation was investigated. The influence of the dispersed seeds on the d ecomposi-
tion process was investigated too. The alkaline aluminate solutions were used as original solutions with a concentration
of Al2O3 having 14.78 g/dm3, αk—1.6 and 127 g/dm3, αk—1.6. For the precipitation processes there were used follow-
ing precipitating reagents—solutions HCl, NaHCO3 and NH4HCO3 with a concentration of 80 g/dm3, dispersants—PEG
6000, (NaPO3)6 and Tween 20. For the decomposition process the dispersed seeds and factories seeds were used. Struc-
tural studies of the aluminum hydroxide particles were carried out by means of the electron-probe microanalysis and
scanning electron microscopy, and phase composition of products was determined by means of X-ray diffraction analy-
sis. Ammonium bicarbonate and Tween 20 were determined as the optimal precipitating reagent and dispersant, corre-
spondingly, resulting in dispersed aluminum hydroxide, which is used as a seed in the decomposition process. It was
established that this product in form of dispersed seed considerably reduces the duration of the decomposition process;
the maximal decomposition of solution (73.9%) was observed after injection of dispersеd aluminum hydroxide into
solution. The final aluminum hydroxide having 90% of particles less than 100 nanometers was obtained within 7 hours
of steady decreasing temperature from 70˚C to 48˚C.
Keywords: Nano-Aluminum Hydroxide; Precipitating Reagents; Dispersants; Alkaline Aluminate Solution;
Precipitation; Particles; Decomposition; Particle Diameter
1. Introduction
Nowadays more than 90% of produced alumina are di-
rected to the production of aluminum, and the demand
for special types of alumina permanently grows with the
pace of development of the industry and the economy [1].
Usage of special aluminas such as nano-dispersed alu-
mina enable the significantly improved properties of ma-
terials with expansion of the area of applications. It can
form the basis for the creation of fundamentally new de-
vices on nanometric scale bringing the considerable eco-
nomic benefit because of their special properties [2]. Ma-
terials containing nano-alumina are widely used in the
aerospace, nuclear, power, metallurgy, electronics, bio-
chemical industry, etc [3].
Production of nanodispersed alumina around the world
in recent years has become a major focus in the field of
new materials based on alumina. Analysis of literature
data and patent information show that the raw materials
for nano-alumina are in general the expensive alkoxides
or inorganic salts and the commercial products of alu-
mina production. It leads to negative effect on the eco-
nomical indexes of production [4-6]. Associated produc-
tion of nano-alumina in alumina production can greatly
raise the price of commercial products with resulting
profit per ton higher to 10 - 100 times compared to in-
dexes in case of metallurgical alumina.
There are physical, chemical and combined methods to
obtain nano-alumina. The easiest and cheapest way is the
method of chemical precipitation from solution of alu-
minum salt. This way the precipitating reagents and dis-
persants cause variation in particle sizes and other prop-
erties of the resulting aluminum hydroxide. Precipitation
of solid aluminum hydroxide from the solution of alumi-
nate may occur in alkaline, acid and neutral media. In
this paper we investigate the process of chemical pre-
cipitation of nanoparticles of aluminum hydroxide from
alkali aluminate solution to identify production condi-