Environmentally-friendly produced dyestuffs and optical ... · Issues concerning the responsible...
Transcript of Environmentally-friendly produced dyestuffs and optical ... · Issues concerning the responsible...
Environmentally-friendly produced dyestuffs and optical brighteners
Dr. Harald Schönberger
Optical brighteners
Dyestuffs for textiles
High fastnesses: light, washing, perspir. very stable substances (non-biodegr.)
Outline Environmental hotspots of the textile value chain Production of dyestuffs and optical brighteners for
textiles (example reactive black 5 and stilbene-based optical brighteners)
Conclusions
Issues concerning the responsible management of the supply chain in the garment sector • Environmental issues (hotspots) • social and governance issues, e.g. establishing fair
working conditions, setting social standards, establishing minimum wages, ensuring occupational safety, imposing a ban on child and forced labour,
Textile value chain – simplified scheme
Fibre production
Yarn production
Weaving or knitting
Textile finishing
Confection and retail
Use phase
Disposal/recycling
rawmaterials
seeds
end-of-life
Raw materials
e.g. reactive black 5 e.g. H acid
Raw materials
e.g. Naphthalene, H2SO4, HNO3, NaOH
brand
disposal
re-use, recycling
AccessoiresRaw materials
rawmater.
Raw materials
Rawmater.
.
.
Synt. fibre prod.
Natur. fibre prod.
Fibre production
Weaving/knitting
Sizing agents
Preparations
Textile auxiliaries
Dyestuff manuf. Dyestuff intermed.
Washing agents
Textile finishing
en
erg
y
wat
er
che
mic
als
was
tew
ate
r
was
tega
s
solid
was
te
Garment manuf.
Use phase
Optical brightenersDiamino stilbene-disulphonic acid
Raw materials
e.g. softeners
Raw materialsPreparations
The textile value chain and mass stream thinking
plus transport activities at all stages
rawmaterials
seeds
end-of-life
Raw materials
e.g. reactive black 5 e.g. H acid
Raw materials
e.g. Naphthalene, H2SO4, HNO3, NaOH
brand
disposal
re-use, recycling
AccessoiresRaw materials
rawmater.
Raw materials
Rawmater.
.
.
Synt. fibre prod.
Natur. fibre prod.
Fibre production
Weaving/knitting
Sizing agents
PreparationsTextile auxiliaries
Dyestuff manuf. Dyestuff intermed.
Washing agents
Textile finishing
en
erg
y
wat
er
che
mic
als
was
tew
ate
r
was
tega
s
solid
was
te
Garment manuf.
Use phase
Hot spot: cotton production
Hot spot: Dyestuff production
Hot spot: Textile finishing
The textile value chain – environmental hotspots
plus transport activities at all stages
The textile chain – actors- and framework-oriented
• the cultivation of cotton due to the high water demand and the high fertiliser and pesticide consumption
• textile finishing (pre-treatment, dyeing/printing, final finishing) causes large quantities of waste water containing high concentration of inorganic and organic compounds
• the production of dyestuffs, pigments and optical brighteners including the intermediates is associated with high amounts of solid wastes and waste water containing non-biodegradable and ecotoxic organic compounds
The textile value chain – environmental hotspots
Production of dyestuffs and optical brighteners needs to be taken into account
Production of dyestuffs and the related intermediates Example: reactice black 5 with intermediate: H acid (globally the most important dyestuff and intermediate)
Production of H acid - 4 production stages - yield referred to naphthalene: ca. 42 %, best ever: 51 %
Production of H acid – Sankey diagram (16 t of raw materials for 1 tonne of product, 1.5 tonnes of organic by-products)
reactive black five 5 – the most important dyestuff in the world ….and H Acid is the most important dyestuff intermediate
Filling bags with reactive black five 5
Inadequate unloading of acids (HCl, H2SO4, NO3)
Inadequate unloading of naphthalene
Single wall HCl and NO3 tanks
Manual removal of a filter sludge
Manual removal of a powder (intermediate)
Inadequate waste water discharge - many severe cases
Inadequate dumping of solid waste
Process- and production-integrated measures to improve the production process – example for J Acid
Improvement of the H Acid production process
Process optimisation (process- and production-integrated)
Neutralisation after sulfonation and nitration
High quantities of solid residues per ton of H acid:
• about 5.6 t gypsum (chalk consumption: about 3 t)
Disadvantage:
reactive extraction as the alternative
Reactive extraction
nitro T acid in sulfuric
acid solution
+ tert. Amine
3 NR3
+ solvent
Ion pair comlex solved
in the solvent
Sulfuric acid (about
30%) for H acid
precipitation extraction
Na –salt solution to reduction
recycling of
amine and
solvent
H acid manufacture –
ion pair extraction after sulfonation and nitration and catalytic
reduction of the nitro group with hydrogen (no iron sludge)
sulfonation
nitration
extraction/
reextraction
cat. hydro-
genation
naphthalene
H2SO4
oleum 65%
T acid
SO2-scrubber NOx to TCR H2 to TCR
HNO3 H2SO4
30%
tert. amine/
solvent H2 Ni catal.
(recycling)
evaporation
fusion
H acid
precipitation
isolation/
drying H acid
NaOH H2SO4 from
extraction
water (reuse) SO2 (sale)
wastewater to treatment
(wet oxidation)
T acid
H2O NaOH 50%
Reduction of raw material
consumption/avoidance of residues
in [ about t/t H acid]
• natural chalk: 3
• soda: 0.25
• sulfuric acid (96%): 3
Reduction of raw material consumption
• gypsum sludge: 5.6
• waste chalk: 0.3
Reduction of residues to be disposed
• CO2: 1.3
Avoidance of CO2-emissions
• Avoidance of iron sludge: 2.4 t
No dumping of gypsum and iron sludge
Improvement of the H Acid production process
Mother liquor
Catalytic wet oxidation process Chemistry and process engineering
Basic chemical reaction
wastewater compounds + O2 + H2O2 CO2 + H2O + biodegr. org. compounds cat.
pH
air
catalyst
hydrogen peroxide
Off-gas
wastewater acid
pre-treated wastewater
temperature
pressure
reactor nozzle
Process parameter
reaction accelaration
higher O2-solubility
increased phases interface
=
=
= pH
Oxidation reactor
Reaction cycles in the cat. oxid. process
Starting and
catalyst cycle
Propagation steps
of Fenton's cycle
Propagation steps
of oxygen cycle
RH = Substrate
Me3+
Me2+
Me3+ + H2O2 O2 + Me2+
R*
H2O2
HO*
HO* + RH
R* + O2
ROO* + RH
R*
HOO*
ROOH
O2
H2O2
HOO* + RH
product
R* R*
Termination:
R* + R*
ROO* + R*
HOO* + Me2+
HOO* + Me3+
Flow chart of a cat. oxidation plant
circulation catalyst H2O2
off-gas
Wastewater
pre-treated
wastewater
acid
Alkali/alkaline
wastew.
air
demister
steam
neutralization
separator
compressor
sludge
storage tank for
wastewaterr
reactor
he
at
exch
an
ge
r
pH
F
F F
T
p
pH
option
F filter
Cat. oxidation plant for contin. operation Technical data
temperature
pressure
hydraulic
load
energy demand
100 – 140 °C
3 – 5 bar
1 – 20 m3/h
Autothermic
(COD>4000 mg/l)
air demand
hydrogen peroxide
(35 %)
catalyst
acid
ca. 10 Nm3/m3
per COD of 1000 mg O2/l
1.5 - 1.8 l/m3
per COD of 1000 mg O2/l
0.3 – 0.8 kg/m3
depends on wastewater-pH
Spec. consumption [/m3 wastewater]
COD: 6- 8 g O2/l
3 - 4.5 m3/h
Catalytic oxidative degradation of H acid and by-productsfrom ist production
LegendTemperature 120°CPressure 3 barEnergy consum.: autotherm.
oxi
dat
ive
deg
rad
atio
nin
%
per
oxi
de
oxi
d.
air
oxi
dat
ion
time in min
Summary of the results of the catalytic oxidation process
reactor feed:
- BOD5/COD (toxic)
- COD reactor feed
< 0.1
5.1 bis 8.0 g O2/l
reactor after oxidation:
- BOD5/COD (biodegradable)
- COD reactor after oxidation
0.7
1.1 bis 2.1 g O2/l
COD removal 74 - 85 %
Comparison of biodegradability:
- BOD5/COD reactor after oxid.
- BOD5/COD of glucose 0.7
0.8
Catalytix oxidation process: operating costs
Operational costs of batch and continuous reactors
Treatment capacity for organic compounds 5 – 8 kg O2 m-3 h-1
Hydraulic load : batch m3/d 1 – 2
continuous m3/d 5 – 300
Cost parameter dimens. consumption EUR/kg O2
batch contin. batch contin.
Energy without air
Hydrogen peroxide
Iron(II)-sulfate
Air oxygen
Sulfuric acid
kWh/kg
l/kg O2
kg/kg O2
m3/kg O2
l/m3
1.00
2.20
0.15
10
?
1.20
1.8
0.13
13
?
0.08
0.59
0.07
0.11
?
0.095
0.48
0.06
0.14
?
Total cost -- -- -- 0.85 0.78
Basic prices:
1 kWh
1 l H2O2
1 kg cat.
1 Nm3 air
1 l H2SO4
0.08 EUR
0.268 EUR
0.462 EUR
0.0108 EUR
0.47 EUR
Raw optical brightener – DNS-based
Stilbene-based optical brighteners
SO3Na
NaO3S
NH2
NH2 + N
N
N
Cl
ClCl
2
0-5°C
pH 4.5-5
SO3Na
NaO3S
NH
NH
N
N
N
Cl
Cl
N
N
N
Cl
Cl
+
NH2
SO3H
SO3H
SO3Na
NaO3S
NH
N
N
N
NH
N
N
N
NH
Cl
Cl
NH
SO3H
HO3S
SO3H
SO3H
2
+ 2 HNRR'
SO3Na
NaO3S
NH
N
N
N
NH
N
N
N
NH
NRR'
R'RN
NH
SO3H
HO3S
SO3H
SO3H
cyanuric chloride
Di-, Tetra-, Hexasulfo Stilbene Brighteners
1. Condensation step
2. Condensation step
3. Condensation step
Synthesis of stilbene-based optical brighteners
Di-Sulpho MEK process
DAS Solution
Synthesis
Crystallization
Filtration
Slurry
MEK distillation
Paddle drier Pretreatment ML
ETP
mother liquor
Mother liquor from optical brightener isolation
Mother liquor: e.g. COD about 12000 mg/l, BOD5 about 200 mg/l very low biodegradability
special treatment required (e.g. wet oxidation)
Hotspot: textile finishing In the focus again (due to Greenpeace activities)
Textile Finishing
Impact of textile finishing on natural water
Impact of textile finishing on natural water
Conclusions and message of this presentation
- Mass stream and LCA thinking required - basis for solutions
- Synchronisation of mass (energy and chemicals) and information flow required (traceability)
- Qualify and quantify the environmental hotspots - Take production of dyestuffs, pigments and optical
brighteners also into account develop appropriate environmental indicators
…. and have a dream
….to convert rivers like this
... into to clear, natural rivers ...
Dr. Harald Schönberger Independent International Consultant on Industrial Integrated Pollution Prevention and Control Carl-Frey-Str. 3, 79288 Gottenheim/Germany e-mail: [email protected] mobile: +49-1795142415