Effective Oxidation Catalysts for Water Treatment and Colour Removal

Effective Oxidation Catalysts for Water Treatment and Colour Removal Liz Manning: liz.manning@catexel.com www.catexel.com

Introduction to Catexel 2 Global leading authority on transition metal based catalysts, accelerators and activators Started in 2006 IP rich, asset light structure Highly innovative company; aim to provide truly novel solutions to resolve complex challenges across industries Current markets include Textiles Paint and coatings Detergents Water Treatment Chemical Synthesis

Innovation at Catexel 3

Temperature ( C) Current Work in Textiles 4 Currently market a catalyst to activate hydrogen peroxide in the cotton bleaching process The catalyst is sold globally and has demonstrated significant benefits in use Bleaching temperatures in process reduced by up to 35 C Improved handling characteristics of the final fabric Reduced processing time Provided Catexel with the collaborative relationships to explore other issues faced by the textile industry 100 90 80 70 60 50 40 30 20 10 0 Add chemicals Standard bleaching Catalyst-based bleaching Time drain Rinse drain drain drain Rinse drain Mn-Me4DTNE Pegasus Current process process More details can be found within our Textile Case History, available to download from our website, http://www.catexel.com/wp-content/uploads/2016/05/textiles-case-history-v1.pdf

Dye bleaching with Dragon and hydrogen peroxide

Environmental Impact of Textile Dyeing 6 World Bank estimates that 17-20% of global water pollution is caused by the textile industry Approximately 2600 L of water is required to produce one t-shirt In Bangladesh, the textile industry there is consuming as much water as the 12 million residents in Dhaka 1 As much as 75% of water used in the dyeing process may be sent to effluent. This effluent will be a variable, complex mixture of Dyes Dressing substance Alkalis Oils Salts of organic and inorganic acids Heavy Metals Reduction in water usage is critical 1 http://documents.worldbank.org/curated/en/614901468768707543/pdf/922610wp0p11950del0for0green0growth.pdf

Introduction to Dragon 7 Me N Me O N Mn O N O Me Me N Mn N Me N Me 2+ Dragon initially commercialised in laundry detergents Catalyst activates hydrogen peroxide under alkaline conditions to give bleaching Depending on experimental conditions, activity can be tuned for different application PROPOSITION: Could Dragon be used to improve the efficacy of rinse-off following the dyeing process?

Dye Bleaching 8 Activity of Dragon was tested with several classes of dyes: Reactive Acid Disperse Vat Reactive dyes were prioritised due to prevalence within cotton dyeing Several variables assessed to conclude optimum performance conditions

% Dye destruction Level of catalyst in solution 9 100 90 80 70 60 50 40 30 20 10 0 0 200 400 600 800 1000 Dragon (um) Solution of Reactive Red 239 treated with different amounts of Dragon Conclusions Demonstrates that lower level of catalyst addition work best Increases potential economic viability

% Dye degradation Sequestrant-Level of DTPA 10 100 90 80 70 60 50 40 30 20 10 0 0 20 40 60 80 100 Time (min) Reactive Blue 220 bleached under range of concentrations of DTPA Conclusions Presence of DTPA in system enhances discolouring Dye destruction linked to level of sequestrant used

% RB 220 degradation Impact of Different Sequestrants 11 100 90 80 70 60 50 DTPA EDDS DTPMP 40 30 Blank, no seq 20 10 0 Level of sequestrant Reactive Blue 220 bleached using different kinds of sequestrant Conclusions Right choice of sequestrant is key to reaching optimal activity Some sequestrant types can even hinder activity

% Colour removal Impact of Carbonate and Catalyst Pre-activation 12 120 100 80 60 40 20 0 Acid Red 88 Reactive Blue 220 Reactive Red 239 Carbonate, ph 9 Iso-pH 9, NaOH Impact of ph stabilisation via carbonate buffer or NaOH addition Impact of pre-activation of Dragon Conclusions Carbonate appears to enhance dye removal, beyond buffering effect In certain circumstances, i.e. certain dyes and conditions, pre-activation of the catalyst may be required to obtain optimal activity

Summary dye bleaching 13 16 reactive & acid dyes tested Tests on reactive and acid dyes confirmed activity of Dragon with full colour removal Some types of dyes required preactivation of the catalyst Limited activity for vat and disperse dyes Catalyst concentration, sequestrant and buffer type should be considered to optimise the system In general, bleaching within 30 min @ 50 C Dye Decolourisation Category Acid Red 88 >95% Azo Acid Red 27 >95% Azo Acid Blue 25 >95% Anthraquinone Acid Blue 45 95% Anthraquinone Acid Blue 80 93% Anthraquinone Procion Navy H-EXL 90% Azo Reactive Red 239 >95% Reactive Red 198 90% Reactive Red 141 >95% Reactive yellow 138.1 50% Azo Reactive Orange 15 80% Reactive Orange 107 55% Azo Reactive Violet 5 >95% Azo Reactive Blue 38 90% Phthalocyanine(Ni) Reactive Blue 71 90% Phthalocyanine(Cu) Reactive Blue 220* (longer to degrade) 90% copper centred

Assessment of activity during Rinse-Off

Introduction 15 Reactive dyeing relatively inefficient: Part of the dye binds to the fabric under alkaline conditions Part is hydrolysed and lost Dyeing efficiency improved by producing dyes with several reactive groups but rinsing still requires multiple stages Large volumes of water containing soaping agents are used Processing time can be long Dragon / H 2 O 2 known to react with hydrolysed reactive dyes and decolourise solutions PROPOSITION: Can the catalyst be used to make rinsing more effective?

Temperature Experimental procedure 16 Cotton swatches dyed at 60 C with 5% R. Black 5 or 4% R. Red 198 2 rinsing sequences potentially applied Padding to reach 100% pickup after each dyeing/rinsing bath 90 80 70 60 50 40 30 20 10 0 15 min, H 2 O 15 min, H 2 O 15 min, Dragon 15 min, Dragon 15 min, H 2 O Note: swatches padded to get 100% pick up between each step Time (min) 10 min, H 2 O Sequence 1 Sequence 2 Bleaching recipe used in rinsing stage with Dragon: 10 mm H 2 O 2., 60 mm DTPMP, ph 10.4, 5 mm Dragon

Dye load (as % of dyeing bath load) Rinsing of RB5 with Dragon, Sequence 1 17 120 100 80 catalyst reference Dragon 60 40 20 0 dyeing bath 1st rinse (50C) 2nd rinse (80C) 3rd rinse (RT)) RB5 rinse-off with no catalyst vs. addition of catalyst in first rinse Conclusions Over 60% of the dye present in first rinsing bath degraded by Dragon When the catalyst is used, 3 rd bath almost clear No dye fading measured on cloths after rinsing (ΔE <0.5)

Dye load (as % of dyeing bath load) Rinsing of RB5 with Dragon, Sequence 2 18 120 100 80 60 catalyst Reference Dragon 40 20 0 dyeing bath 1st rinse (80C) 2nd rinse (50C) 3rd rinse (50C) RB5 rinse-off with no catalyst vs. addition of catalyst in second rinse Conclusions 80%> colour removal by Dragon in 2 nd rinsing bath (vs. ref) Similar results after 2 nd rinse with Dragon or 3 rd rinse without catalyst 3 rd rinse redundant if catalyst used

Dye load (as % of dyeing bath load) Rinsing of RR198 with Dragon, Sequence 2 19 180 160 140 120 100 80 60 40 20 catalyst Reference Dragon 0 dyeing bath 1st rinse (80C) 2nd rinse (50C) 3rd rinse (50C) RR198 rinse-off with no catalyst vs. addition of catalyst in second rinse Conclusions Dragon also effective at rinsing Reactive Red dye Over 80% colour removal in 2 nd bath; potentially eliminate third rinse Still no dye fading on clothes

Conclusions & Proven Benefits 20 Experiments performed in Leiden showed that Dragon is able to shorten rinsing process of dyed clothes Comparison of clothes rinsed with and without catalyst showed no colour change (ΔE <0.5) whatever the conditions tested Significant savings achievable (time, water, energy). Process currently used in India Customer reported: Production increase. Water Savings. Energy Savings.