C22 2 voc substitution techniques _final-web

TRP 1
VOC Emission Substitution
Techniques – Surface Cleaning
IAMC Toolkit
Innovative Approaches for the Sound
Management of Chemicals and Chemical Waste

2
This presentation gives an overview of cleaning
techniques, methods and requirements in the
chemical industry with a particular focus on the
role of solvents.
It introduces the reader to the potential of
substitution of VOC solvent use due to the
introduction of improved cleaning technologies,
including solvent recovery systems.
Introduction
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1. Solvent Use, Emissions and Environmental
Impact
2. Surface Cleaning: Substitution Techniques
 Water-based cleaning systems
 Carbon dioxide cleaning
 Plasma technology
 UV cleaning
 Laser cleaning
 Thermal paint stripping
3. Good Practice Example
Contents

Solvent Use, Emissions and
Environmental Impact
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transmitted or manipulated
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Cleaning is mandatory, it is directly related to
production efficiency and quality.
Importance of Cleaning Substances and Costs
Large amounts of
solvents are required
(“Better more than less”
approach)
Expensive and often
highly hazardous
substances
Company image is
improved if less
harmful substances/
methods are used

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Solvents Used: VOC With Specific R-Phrases
(GHS: H-Phrases)
The use of CMR substances (carcinogenic, mutagenic or toxic to
reproduction) or halogenated solvents is subject to specific requirements.
 Halogenated solvents:
 Excellent cleaning properties and suitable for a wide range of materials
 High solvency power for a large variety of substances
 Low surface tension
 Non-flammability
 Rapid and residue-free evaporation, good recyclability
 Examples of use of halogenated solvents:
 Perchloroethylene (PER): industrial surface cleaning of aluminium, magnesium, zinc, brass, etc.
 Dichloromethane: paint stripping
 Trichloromethane: vapour and cold cleaning
 N-propyl bromide: removal of solder flux, wax, oil, grease from electronic parts, metals and other
materials

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Solvent Use: VOC Without Specific R-Phrases
 Solvents used for surface cleaning:
 Alkanes (isododecane, iso-paraffins, kerosene)
 Alicyclics (cyclohexane)
 Alcohols (isopropanol, 1-butoxypropan-2-ol)
 Polar aprotics (N-methylpyrrolidon)
 Ketones (acetone, diketone)
 Esters (N-butyl acetate)
 Ethers (glycol ether)

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Solvent Consumption and Emission Levels
 Chlorinated solvent consumption has declined over recent
years in Europe due to the following reasons:
 Increased number of closed systems and improved process
management (emission control, solvent recycling systems, better
management of waste)
 Legal restrictions
 Shift from chlorinated solvents to alternative solvents
 More stringent carcinogenicity classification of trichloroethylene

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Key Environmental and Health Issues
 VOC with specific R-phrases
 Main environmental and health issues with CMR labelled solvents:
carcinogenic, mutagenic, toxic to reproduction
 Perchloroethylene and trichloroethylene are toxic/harmful to aquatic
organisms
 Halogenated solvents are toxic to the aquatic environment
 VOC without specific R-phrases
 1-butoxypropan-2-ol, isopropanol, cyclohexane, N-methylpyrrolidon,
acetone: harmful and may cause irritation to eyes and skin
 Cyclohexane: highly toxic to the aquatic environment
 Most organic solvents are highly flammable

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Key Environmental and Health Issues
 VOC emissions to air, water, soil and groundwater occur
during:
 Storage of solvents
 Cleaning processes
 Spills and leakages
 Waste generated by the processes containing solvents
needs to be disposed in a way that prevents the emissions
of VOC to air, water and soil.

Surface Cleaning: Substitution
Techniques
 Water-based cleaning systems
 Carbon dioxide cleaning
 Plasma technology
 UV cleaning
 Laser cleaning
 Thermal paint stripping
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VOC-Free Systems
Substitution of VOC
solvents with water-
based cleaning systems
Carbon dioxide
cleaning
Plasma technology
UV cleaning Laser cleaning Thermal paint stripping

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Substitution of VOC Solvents with Water-Based
Cleaning Systems
 Aqueous solutions of acid, alkali or neutral cleaners can replace
halogenated and non-halogenated solvents in the industrial cleaning of
hard surfaces:
 Steel
 Aluminum
 Magnesium
 Copper
 Neutral pH cleaners are used for intermediate and final cleaning.
 Strongly alkaline cleaners are used to obtain very clean surfaces, e.g.
before coating processes.
 Acidic solutions are used to clean metals (e.g. to remove metal oxides).

 Plastics
 Coated surfaces
 Glass
 Electronic components

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Substitution of VOC Solvents with Water-Based
Cleaning Systems
 Investment costs for water-based installations:
 50% lower than solvent-based systems (enclosed systems with air extraction)
 Operational costs:
 Depending on the cleaning medium and requirements for bath maintenance
 May be more energy intensive than solvent-based cleaning (need for drying stage,
final cleaning with deionized water)
 May have to be maintained/replaced more regularly
 Efficiency of water-based cleaning can be enhanced by:
 Ultrasonic or megasonic cleaning systems
 Aqueous systems vary in character and need to be adapted to the
product and production cycle under consideration to achieve the
required cleanliness.

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Carbon Dioxide Cleaning
 CO2 can be used as solvent to remove oil, grease and other
organic contaminants.
 Technique:
 Pressurized air (300m/s) is used to blow pellets of dry ice onto the surface to be
cleaned.
 Technique suitable for:
 Removing small amounts of organic contaminants
 Cleaning electrical components and sensitive parts in situ
 High degree of cleanliness
 Costs:
 Machine: €9,000-€14,000
 Dry ice: €0.6/kg (machine consumption: 30-50 kg of dry ice per hour)

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Plasma Technology
 Use/Application:
 Removing grease, oxides, oils, silicones in the automotive and electronics industries
(before industrial painting or for pre-treatment before gluing or soldering)
 Removing thin films of organic contaminants (< 1μm)
Remark: Plasma technology is ineffective when inorganic materials are present.
 Technique:
 Ion bombardment
 Two techniques available: low-pressure plasma system (LPPS) and atmospheric
pressure plasma system (APPS)
 Process gas: argon or oxygen (the choice of the process gas depends on the
material to be cleaned and the composition of the contaminant)
 Leaves no residues on the surface – no need for rinsing

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Plasma Technology
 Often combined with a pre-cleaning step (water-based or semi-
aqueous pre-cleaning)
 Investment costs:
 Depending on the size of the installation (2-13,000 l): €8,000-
€400,000
 Operational costs:
 Very low, no specific chemical required

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UV Cleaning
 Used to remove organic contaminants from the surface of
substrates (e.g. photoresists, semiconductors)
 Cleaning agents: oxygen-free radicals that decompose organic
contaminants
 Best results achieved with thin layers of organic contaminants
 Pre-cleaning step may be required
 Ozone is produced during the cleaning process
 Cleaning time can be short (5 to 10 minutes)
 Common technology (same principle applied in other
industrial sectors, e.g. water treatment)

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Laser Cleaning
 Applicable to high-quality surfaces in the automotive, aviation or
electronics industries
 A laser heats and vaporizes the contaminants (vapour filters required).
 Small areas of a part can be cleaned (rather than the
entire piece).
 Technique:
 Laser radiation pulsed to remove organic protective layers or coatings
 No additional chemical needed
 Suitable for paints, adhesives, coatings, rubber residues, plastics,
oxide layers
 Contaminant needs to be known to calibrate the laser frequency
 High investment costs but low operational costs

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Thermal Paint Stripping
 Used for thermo-resistant materials (e.g. steel, aluminium,
etc.)
 Technique:
 Process takes place in an oven at 250-430 °C and takes 3 to 12
hours
 Sandblasting or high-pressure water washing are used to remove
the remaining ash
 Not suitable for wood and plastics (degradation of the materials)
 Exhaust gases need to be treated by thermal oxidation

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VOC-Reduced Systems
 If the complete substitution of organic solvents is not
possible, one can switch to systems with reduced VOC
content.
 The use of products with very low VOC content can
replace systems with higher solvent content:
 Semi-aqueous cleaning systems (e.g. micro phase cleaning
system (MPC) with a VOC concentration of 10%)
C12_Substitution of chemicals

Good practice example
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Good Practice Example

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Good Practice Example
 A company decided to switch to plasma cleaning technology to
degrease and activate the surface of plastic parts.
The new system has the following operational characteristics:
- Cleaning volume per process: 20-40 l
- Process duration: 15-20 min
- Oxygen consumption: approx. 0.1 l/min  1.5 l/process
- Oxygen costs: approx. €4 for 1,000 l
- Electrical power: approx. 2.5 kWh  0.83 kWh/process
- Maintenance: approx. €2,000 per year
What are the company’s VOC consumption and emissions ?
Answer: By using the plasma cleaning technology, the VOC consumption and emissions can be
reduced to zero.

Toolkit/CSDandISSPPRO 25
Key messages
 The volatile proprieties of VOC solvents induce a high
percent losses.
 Several solvent substitution technique with less harmful
substances or technologies are available.
 The initial financial and personnel training investment
needs to be balanced with the long term saves in terms of
solvent consumption and emissions.

Sources
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Fusce posuere, magna sed pulvinar ultricies,
purus lectus malesuada libero, sit amet magna
eros quis (ARIAL 32).
Sources
 CSD Engineers, Switzerland/ISSPPRO, Germany, 2015
 European Commission - DG Environment: Guidance on
VOC Substitution and Reduction for Activities Covered by
the VOC Solvents Emissions Directive (Directive
1999/13/EC), Europe, 2009.
27UNIDO│IAMC Toolkit | Images may not be copied, transmitted or manipulated

Fusce posuere, magna sed pulvinar ultricies,
purus lectus malesuada libero, sit amet magna
eros quis (ARIAL 32).
Images
 CSD Engineers, Switzerland, 2015
28UNIDO│IAMC Toolkit | Images may not be copied, transmitted or manipulated

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This presentation was prepared with the requested diligence
and with the generally accepted principles of the relevant
field.
If a third party uses the contents of the presentation in order
to take decisions, the authors disclaim any liability for any
kind of direct or indirect (consequential) damage.
Disclaimer

C22 2 voc substitution techniques _final-web

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