Well over a century ago borates – usually the disodium tetraborate decahydrate salt
(borax decahydrate*, Na2B4O7.10H2O) - became popular wash-day additives. They were famed,
once they became easily and cheaply available, for their gentle but strong cleaning action.
Then in 1907 came Persil, the first perborate-based laundry detergent: Perborate-silicate.
Sodium perborate was regarded then as a stable and effective solid form of available oxygen:
but little more than that. However, as research into detergent and borate chemistry has advanced,
more and more of its contributions to cleaning activities have been identified and quantified.
Far from being a vehicle for oxidative bleaching alone, borates provide a multiplicity of useful
washing functions. As outlined in each section, borates play a role in most laundry and cleaning products.
 |
Enlarge Image |
| * Throughout this publication 'borax' refers to both disodium
tetraborate decahydrate (Na2B4O7 - .10H2O)
and disodium tetraborate pentahydrate (Na2B4O7 - .5H2O) salts unless otherwise indicated. |
Once sodium perborate has hydrolyzed in the wash liquor to release its hydrogen peroxide
(or with a low temperature activator, delivered a peracid), the tetrahydroxy borate anion (B(OH)4 - - -)
remains in solution. It works as a detergent builder in key areas and performs cleaning activities of
its own, in synergy with the other detergent ingredients.
This review is based on published work in the field carried out by researchers outside Borax, and also
by Borax Technology. It records the significant borate contributions to the wash, and presents a general
overview of the chemistry and performance indicators involved. A bibliography on the main topics summarized
here is appended.
There are distinct washing and cleaning product categories where borates play their parts and demonstrate
their versatility: each exploits a distinct combination of borate properties.
|
|
Future directions in detergents – the contribution from borates
Looking ahead in the field of detergents, emphasis will be on the development of products which
support the guiding principle of sustainability. In practical terms, this means the use of less
chemicals per capita (and therefore more concentrated products containing multifunctional ingredients),
less water and energy for washing. In addition, there will be a greatly increased focus on products
for the developing markets. Here, the need will be for advances in product performance, but at an affordable price.
This review emphasises the roles that borates can play in meeting these detergent industry challenges.
One example of this is the contribution that sodium perborate can make to the design of more concentrated
products through the use of its multifunctional bleach and builder systems. Another is the challenge of
low temperature (low energy) washing. In this context activated sodium perborate and borates themselves
are demonstrated to deliver excellent cleaning performance under developing world conditions (especially
where pre-soaking is practiced). Future constraints on water consumption will actually improve the performance
of sodium perborate and, quite separately, will demand products which are more soluble. Unique interactions
between borates and starchderived ingredients (surfactants, for example) which are increasingly being employed
in detergents, result in a substantial increase in the solubility of such materials. The aforementioned are
only a selection of the many borate effects, described in detail in this review, which can assist the formulator
in the design of detergent products for the future.
Glossary on borates
H3BO3 - boric acid, ortho boric acid
Na2B4O7.5H2O - borax pentahydrate, disodium tetraborate pentahydrate
Na2B4O7.10H2O - borax decahydrate, disodium tetraborate decahydrate
Na2B4O7 - anhydrous borax, disodium tetraborate
NaBO2.4H2O - sodium metaborate |
|
