ALUMINUM-GLUCONIC ACID COMPLEX CORROSION INHIBITOR

AGENT ANTI-CORROSION A BASE D'UN COMPLEXE D'ALUMINIUM ET D'ACIDE GLUCONIQUE

English Abstract

ALUMINUM-GLUCONIC ACID COMPLEX CORROSION INHIBITOR
Abstract of the Disclosure
AlC13 ? 6H20/gluconic acid reaction complex is disclosed
as a new product for use for control of corrosion of iron
and steel surfaces in aqueous systems.

Claims

CLAIMS
1. The method for control of corrosion of
iron and steel surfaces in aqueous systems which comprises
maintaining in said system an effective amount, 0.1-500 ppm
of water, of a corrosion inhibitor complex made by reacting
together aluminum chloride hexahydrate and gluconic acid,
in a mol ration of 1:2 to 2:1, said complex being the sole
corrosion control additive present.
2. Method of Claim 1 in which the amount of
complex is about 1-30 ppm.
3. Corrosion inhibitor complex made by
reacting aluminum chloride hexahydrate with gluconic acid
in water in a mole ratio of 1:2 to 2:1.
-5-

Description

The present invention relates ~o a novel complex as a
corrosion inhib~tor in aqueous systems. A purpose o ~his
inven~ion is to provide corrosion protection with non-toxic
compounds for iron and steel metal parts such as heat
exchangers, engine jackets, pipes and particularly to prevent
metal loss, pitting and tuberculation of iron base alloys
which are in contact ~it~ water.
Thus the present invention provides a method for control
of corrosion of iron and steeI surfaces in aqueous systems
which comprises maintaining ~n said system an effective
amount, 0.1-500 ppm of water, of a corrosion inhi~tor
complex made by reacting together aluminum chloride hexa-
hydrate and gluconic acid, in a mol ratio oE 1:2 to 2:1,
said complex being the sole corrosion control additive present.
In a preferred embodiment the amount of the complex is about
1 to 30 parts per million.
In another aspect the present invention provides a
corrosion inhibitor complex made by react~ng aluminum
chloride hexahydrate with glucon~c acid ln water in a mole
ratio of 1:2 to 2:1.
~ 1 ~
. ... _ .. ._.. ...... ........ . .

8 7 3
The corroslon ~nhi~itor complex is pxepared as follows.
Aluminum chIortde hexahydrate, AlC13 6H20, 35.8 g, is
intimately mixed with 64.2g~ of aqueous ~luconic acid
solution (46.7% active) at about 25C., for about 60 minutes.
The mix undergoes a reaction to form a co~plex of indetermin-
~te structure. The produce is not isolated, but is used in
a~ueous solut~on. Other ratios have been tried, e.g. 1:2 to
2:1 mols of AlC13 6H20 per mol of gluconic acid, these other
ratios show no advantage over the complex described above
which is approximately 1:1 molar.
The complex is tested as a corrosion inhib;tor using a
water containing 110 ppm calcium, 51 ppm magnesium, 185 ppm
bicarbonate, 492 ppm chloride and 630 ppm sulfate. The tests
used for this evaluation are described by J. Jacob and H. Kerst
in Materials Protection and Performance, Vol. 16, No. 4, April
1977. The tests were run at a pH of 6~5-8, at a temperature
of 130F for 24 hours. Results are given in the table.
It will be noted that results are given as a % of corrosion
pxotection, determined as follows: The corrosion rate of a
non-treated water was 58.5 MPY, that of Example 2 ~Table of
Results) was 30~5 MPY. The follow~ng equation was used to
calculate the percent corrosion protection:

1 3 6~87~
MPY (blank) - MPY (inhibited test) x 100
MPY ~blank)
percent corr. prot., e.g., 5~ 3- 30 5 x lO0 = 47.7%
58.3
Concentration of % of Corrosion
Aluminum-Gluconic Protection for
Acid Complex lOlO Steel_Coupons
Example
1Blank (no treatment) 00
2 3.4 ppm 47.7
3 6.8 ppm 76.1
4 6.8 ppm 73.0
6.8 ppm 75.0
6 10.2 ppm 73.0
In treating an aqueoU5 system by the process
of this invention, we maintain about 0.1-500 ppm of the
inhibitor complex in the water, and more preferably,
about 1-30 ppm.
; This inhibitor can be blended with any well
known scale inhibitors, dispersants and yellow metal
corrosion inhibitors such as benzotriazole or mercapo-
benzothiazole. Typical industrial applications where
instant invention is useful include water treatment,
radiator coolant, hydraulic fluid, anti-freeze, heat
transfer medium and petroleum well treatment.
Gluconates are known in water treatment. U.S.
Patent 3 095 862 teaches calcium gluconate as a carbonate
removerO U.S. 3 711 246 discloses the use of sodium gluconate

~ 161~t~3~
with sodium silicate for oxidative corrosion control.
U.S. 4 108 790 discloses sodium and ammonium glaconates for
oxidative control in cooling water systems. U.S.
4 120 655 teaches a phosphoric ester plu5 a gluconate of
a metal of groups II to VIII of the periodic table for
ferrous corrosion control. However, so far as is known we
are the first to use the herem described AlC13, 6H20/gluconic
acid complex as the sole effective corrosion control
additive for iron and steel surfaces.
~i .