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Low Temperature Bleaching
The rising cost of energy and raw materials, coupled
with growing environmental concern regarding
industrial processes with high chemical loads and
heavy water usage, have presented textile mills and
their technology suppliers with a need to find
solutions that can support more sustainable
operations. These issues have been ongoing drivers
in the research and development of additives and
auxiliaries that promote cleaner and faster processes,
while delivering additional performance and
cost-in-use savings. Catexel is a global company
which produces transition metal based oxidation
February/March 2018
catalysts, accelerators and activators. The
technologies have already been translated into
commercial success in the coatings, detergents and
cleaning, and textile industries and Catexel is
developing new applications across a variety
of markets.
The technology
When a catalyst demonstrating superior stain
removal was discovered by Catexel, that could
achieve cleaning at lower temperature wash cycles
for household laundry, their lead research team saw
an opportunity to maximise its potential in industrial
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applications. The real catalyst for change came when Pegasus’ ability to activate hydrogen peroxide at
commercialised this technology for low temperature textile auxiliary houses the opportunity to promote the
Catexel – the oxidation catalysis experts that first
reduced temperatures and pH (alkalinity) also offers
bleaching (LTB) of cellulosic substrates – identified
technology as an important point of difference across
another, more interesting product in its extensive
library of manganese and iron catalysts, accelerators the value chain – particularly from an environmental
perspective. As well as achieving high bleaching
and activators. That product was Pegasus performance at more moderate temperatures, the
(Me4DTNE). Pegasus is a stable manganese technology can be used to shorten the process cycle
metal-complex catalyst, Pegasus is a highly selective for fabric treatment and, in some cases, to treat
oxidation catalyst for use with hydrogen peroxide in wastewater streams. It can be an opportunity for
aqueous oxidation processes. It is highly water textiles businesses seeking to make positive change
soluble and more stable in strongly alkaline to their existing processes these all-important,
conditions, making it ideal for widespread use in the incremental steps towards a more sustainable future
textiles market for raw cotton bleaching. carry a clear corporate social responsibility message.
The growing list of hydrogen peroxide activation Impact
applications includes wood pulp delignification and Processes incorporating Pegasus Approved Systems
brightness enhancement, and industrial and are evidenced as being more energy efficient, cost
institutional cleaning, including commercial laundry effective, environmentally acceptable and quality
application. While sharing a very similar chemical assured. Indeed, users across the 65% of the market
structure to the original Dragon technology used in that relies on hydrogen peroxide processes to
detergent applications, it demonstrated a much wider achieve full whites or produce a consistent light
combination of hard performance benefits and “soft” colour for subsequent dyeing (half-bleach),
aesthetic benefits, which results in highly predictable consistently observe:
activity and much less likelihood of fabric damage • Reduced chemical load, which contributes to cost
through improper use. savings and supports improved environmental
profile claims (some TAHs report being able to
For the majority of customers, operating in some of reduce caustic soda by 30%, for example)
the most ecologically sensitive parts of the world, • Up to 15% unit cost savings per tonne of cotton
there are certain production issues to contend with bleached, taking into account energy, chemical
and so any ‘drop in’ solution needs to be suited to a load and increased cotton yield
wide range of processing conditions. Considerations • As much as 15% in heating cost savings and 10%
such as water quality can be overcome with a in electricity savings due to lower temperature
product that is proven to consistently perform where bleaching activity
typical processes are followed. Perhaps the ease in • Increased asset utilisation and higher output due
which Pegasus can be adopted and the predictability to shorter bleaching, heating, cooling and rinse Outlook
of its behaviour offer some of its biggest benefits in cycles Up to now, Pegasus’ potential has only been fully
accommodating a variety of systems established in leveraged for exhaust bleaching processes and yarn
widely different territories. This consistent delivery is a These statistics show how Pegasus has already bleaching. Cold-pad batch and continuous methods
result of the highly stable, highly selective nature of helped promote positive change through direct offer interesting development opportunities. For the
the chemistry and the savings in time and financial and operational benefits - or by creating a former, the main benefit would be the cost savings
consumables that can be achieved are clearly more benign and better handle end product. Its possible through reduced chemical load. In cold-pad
evidenced in the figure below: adoption by textile processors across the globe as batch, chemical reduction would also be a factor and
the low temperature bleaching process of choice is, the potential for time savings an attractive proposition.
as much testament to the chemistry at play, as it is
the pioneering management team that developed Innovations beyond low temperature bleaching
and commercialised the platform. But, ultimately, applications are too being tested with industry. A
these “greener” technologies are being introduced
thanks to the commitment and reach of the textile small number of other activators and catalysts in stages, already with the waste streams from the dye
auxiliary houses (TAHs), acting as the strategic Catexel’s portfolio have been identified in the baths, it is clear how only very small quantities of
treatment of wastewater streams from the reactive
go-to-market partners of research and development dying of cotton and the chart below shows how catalyst could have a big impact at every stage
companies, like Catexel. By providing critical effective this application is proving in field tests and involved in the industrial treatment of cotton.
technical service, support and advice TAHs are the the time and cost saving benefits it would bring. Please visit the source (http://www.catexel.com/) for
chief facilitators helping the industry to forge a more When considering the effluents from the bleaching further details.
sustainable and, actually, more cost efficient future.
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