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What's in your cleaning tank?
What's in Your Cleaning Tank? B y J o h n B. D u r k e e , P r e s i d e n t ,
Creative EnterpriZes
he pace of change in industrial cleaning is not glacial. But sometimes one has to look over a great distance to find it. That's the purpose of this column. Yet, we're not going to use our eyeglasses to recognize change. We're going to use a telescope to look backward and forward. Significant change in industrial cleaning doesn't happen in one year.
T
SLOW BUT STEADY A sea change is defined as metamorphic or being a gradual evolution from one state to another. That's what's been h a p p e n i n g with users in industrial cleaning over the last 20 or so years. Three good reasons why change in metal/industrial cleaning is slow-paced are: a Operation of metal cleaning is diversified across multiple industries and businesses. One purpose of Metal Finishing is to allow those who machine metal screws to understand change in stamping of metal housings, and decide if it affects them. • Environmental regulations are a major driver of change in cleaning technology. Legislatures have inertia. And there must be allowance of time for compliance with regulation. So the time between recognition of an environmental need and implemented regulation are usually measured in partial or full decades. The CFC ban is a good example. • It's difficult for users to convince management to authorize capital for adoption of new cleaning technology. The unit operation of cleaning usually produces improvements in quality, which are more difficult to justify than are improvements in cost.
A TELESCOP|C ViEW TO THE PAST Though slow-paced, change in industrial cleaning is significant and broad-based. The sea change in how cleaning is done is described in Table I. A THLES©@P|@ ViEW T@ THE FUTUBE Change is the only constant. In this column we are going to speculate about s u b s t a n t i a l changes to what constitutes a cleaning agent. There is good reason to think they might actually become available in some form. Your future might include one. Tomorrow's cleaning agents might: s Be nonorganic ionic liquids that don't evaporate and produce pollution. • Be biological solvents (enzymes and bacteria) that 46
Table
I: A Sea C h a n g e In I n d u s t r i a l C l e a n i n g
Change From:
Change To:
Generally powerful clean,ng agents
Ones of power to remove a few speo,flc sods
Powerful solvents
Ones of lesser power
Cleamng agents that present hazard to humans
Cleaning agents that present much less hazard to humans
Cleamng agents about which there ,s data showing harmful : effect to the environmetlt
Cleaning agents about which there is limited or no such data
Solvents that are used in "cold" or open cleaning operations
Solvents that are used In vacuum or pressurized sealed cleaning systems
Inflammable solvents
Flammable solvents
! Cleamng agents that cost us dimes per pound A philosophy of "use once and discard"
Little governmental regulation affecting industrial cleaning
Cleaning agents that cost us dollars per pound A philosophy of "use once and consider recovery and possibly recycle" Governmental mandate about manufacture, use, and disposal of cleaning agents and sods
Un'concern about cleaning methods
Controversy, sparked by "political correctness." about cleaning methods
Solvent cleamng
Aqueous clean,ng, or no cleamng
remove soils via solution and then oxidize soils to harmless byproducts. • Not be liquids--they might be dendrimers impregnated into a solid structure. If the past is a guide, they may be something that we haven't yet conceived of. | O N | C LIQUIDS If you had been at Kitty Hawk, N.C. in December 1903, you might have witnessed the initial manned flight by the Wright brothers with a heavier-than-air craft. Had you done so, would you have telephoned and established a frequent flier account so you could earn a free trip to Hong Kong? Probably not. Would you have bought stock in firms providing transcontinenta] railroad service? Probably no.t either. That's where we are, almost, today with ionic liquids. Ionic liquids are organic salts with melting points under 100 °, often even lower than room ternperature. Recently, they are employed more and more as substitutes for the traditional organic solvents in chemical reactions. Most of the familiar cleaning agents (water, ethanol, www.metalfinishing.com
/
hexane, etc.) are molecular. That is, regardless of whether they are polar or nonpolar, they are basically constituted of molecules. Ionic liquids are different. They are composed of ions, not molecules. Ionic liquids are "designer solvents." The degree of flexibility is nearly infinite. Another author wrote: "If you look at j u s t the number of papers and patents in ionic liquids and plot that versus years, it's gone up exponentially." Researchers studying ionic liquids aren't certain of their intermolecular structure. In 2004, most believe that they remain liquid at room temperature because their ions don't pack together well. Combining bulky, asymmetrical cations with smaller, evenly shaped anions has been described as "like gluing an octopus to a basketball." This leaves the ions disorganized, without a regular s t r u c t u r e - - i n other words, in a liquid phase. O t h e r t h a n their chemical character, ionic liquids have a unique p r o p e r t y t h a t m a k e s t h e m of interest to those doing chemical cleaning. Ionic liquids don't evaporate. Ionic liquids aren't volatile. From the perspective of environmental management, that is an extremely good thing. All ionic cleaning agents would, supposedly, be VOC exempt in both the U.S. (unreactive with UV light) and in Europe (very high boiling), not contribute to global warming, and not be hazardous air pollutants (HAPs). That's not necessarily good news for those formulating solvent-based paints and coatings. After all, a wet solvent that doesn't e v a p o r a t e will produce a p a i n t or coating t h a t n e v e r d r i e s - - i t always runs. A w e t cleaning agent t h a t has to be removed by v a c u u m drying in February 2005
every application won't be popular among many. The major concern about ionic solvents for those interested in industrial cleaning is future availability. Parts cleaning is not a huge sales outlet for producers of chemicals. This leads to questions. Will there be any ionic solvents developed for cleaning? What range of solubility parameters will or can be available? Will the flexibility provided by oxygenated cleaning solvents be provided by a s p e c t r u m of ionic cleaning solvents? The minor concern about ionic solvents is price. Today no user could afford ionic solvents for cleaning, no m a t t e r to w h a t extent they can be recycled. As d e m a n d increases, prices will fall. It's not fair to presuppose that ionic solvents will be overly expensive--who would have proposed in 1903 that one could fly from New York to Miami for $100? But it is an open quest i o n - w i l l ionic solvents be affordable for cleaning work?
Circle 014 on reader information card or go to www.thro.to/webconnect
BIOLOGICAL SOLVENTS This technology, and associated products, are not true cleaning agents. Soils are not dissolved. R a t h e r t h e y are removed with biologically active s u r f a c t a n t s that are applied at room temperature and near-neutral pH. The cleaning solution cont a i n s n o n y l p h e n o l - f r e e surfactants. These t e n s i d e s act to r e d u c e t h e s u r f a c e t e n s i o n of water. W h e n p a r t s e n t e r t h e
Circle 020 on reader information card or go to www,thru,to/wehcongect
47
•
"
~
~.~{ ,~-~4~" e2"~-,,~-j.~,; ,.,,,~,,_ - %~.~ ~-.~.......... ~ y ~:~' ,,,,t,,,. '., '">,'-, '~'r,',,,
eral days). Consequently, this approach is not useful for cleaning parts with a high soil level. In this situation, the size of the oxidation tank can literally dwarf the size of the manufacturing unit. Please note that the soil does not have to be disposed when biological cleaning is used. The soil is oxidized to CO2 and H20. The only material to be disposed is a concentrate of expired organisms (sludge). Usually, the cleaning package of surfactants is not oxidized and can be recycled.
X
-;.
%
CLAR|FII©AT|@N Table
II1: C o m p a r i s o n
Figure 1'The structure of a general dendrimer
solution, tensides lift oil and impurities off the parts and emulsify them into microparticulates that are then consumed by microorganisms in the bath. The bacteria is safe for h u m a n contact and ]s comparable to that used in the food, dairy, and brewery industries. As the volume of oil increases, the organisms multiply in direct proportion, maintaining optimal cleaning power. The microorganisms become more effective as the oils emulsify. The oil-based soil is oxidized at a slow pace (sev-
i
Drying
Projected Instantaneous Costs as Energy Requirements-- K W 2 to 4
Air Blowoff
8 t o 22
Hot Forced Air
10 t o 3 0
The following table was inadvertently ommitted from page 52 of last month's column. John B. Durkee, H PhD, PE, ~s a consultant tn critical and metal cleaning with Creatwe EnterpriZes, a consulting ftrm ~n Hunt, Texas. You can contact the author at (e-mail) [email protected]; (phone) (830)-238-7610; (fax) (612)-677-3170. I#f
Systems that Set the Pace in Produ ,-t,,,,t,,
~
Projected
Centrifugal
GUYSON MULTI-BLAST ° ,
of
Costs
Drying Method
| _ ~
,,,,, ', ',
Automate your blasting process for consistent quahty results, control over component surfaces and lower production costs
SVST
TW..S
Phone 401-253-0050 Fax 401-253-1602 Webs,te www systinc c0m
Bathminder Brightener Feeder
.gayson.com [] [] [] []
Shot Peen Etch, Prep Deburr Strip
r~ Oescale [3 Clean [] Deflash [] Decorate
Circle 016 on reader information card or go to vvww.thru.to/webconnect 48
Circle 027 on reader reformation card or go to w w w thru to/webconnect www
metalfinishing.com
Creative EnterpriZes
he pace of change in industrial cleaning is not glacial. But sometimes one has to look over a great distance to find it. That's the purpose of this column. Yet, we're not going to use our eyeglasses to recognize change. We're going to use a telescope to look backward and forward. Significant change in industrial cleaning doesn't happen in one year.
T
SLOW BUT STEADY A sea change is defined as metamorphic or being a gradual evolution from one state to another. That's what's been h a p p e n i n g with users in industrial cleaning over the last 20 or so years. Three good reasons why change in metal/industrial cleaning is slow-paced are: a Operation of metal cleaning is diversified across multiple industries and businesses. One purpose of Metal Finishing is to allow those who machine metal screws to understand change in stamping of metal housings, and decide if it affects them. • Environmental regulations are a major driver of change in cleaning technology. Legislatures have inertia. And there must be allowance of time for compliance with regulation. So the time between recognition of an environmental need and implemented regulation are usually measured in partial or full decades. The CFC ban is a good example. • It's difficult for users to convince management to authorize capital for adoption of new cleaning technology. The unit operation of cleaning usually produces improvements in quality, which are more difficult to justify than are improvements in cost.
A TELESCOP|C ViEW TO THE PAST Though slow-paced, change in industrial cleaning is significant and broad-based. The sea change in how cleaning is done is described in Table I. A THLES©@P|@ ViEW T@ THE FUTUBE Change is the only constant. In this column we are going to speculate about s u b s t a n t i a l changes to what constitutes a cleaning agent. There is good reason to think they might actually become available in some form. Your future might include one. Tomorrow's cleaning agents might: s Be nonorganic ionic liquids that don't evaporate and produce pollution. • Be biological solvents (enzymes and bacteria) that 46
Table
I: A Sea C h a n g e In I n d u s t r i a l C l e a n i n g
Change From:
Change To:
Generally powerful clean,ng agents
Ones of power to remove a few speo,flc sods
Powerful solvents
Ones of lesser power
Cleamng agents that present hazard to humans
Cleaning agents that present much less hazard to humans
Cleamng agents about which there ,s data showing harmful : effect to the environmetlt
Cleaning agents about which there is limited or no such data
Solvents that are used in "cold" or open cleaning operations
Solvents that are used In vacuum or pressurized sealed cleaning systems
Inflammable solvents
Flammable solvents
! Cleamng agents that cost us dimes per pound A philosophy of "use once and discard"
Little governmental regulation affecting industrial cleaning
Cleaning agents that cost us dollars per pound A philosophy of "use once and consider recovery and possibly recycle" Governmental mandate about manufacture, use, and disposal of cleaning agents and sods
Un'concern about cleaning methods
Controversy, sparked by "political correctness." about cleaning methods
Solvent cleamng
Aqueous clean,ng, or no cleamng
remove soils via solution and then oxidize soils to harmless byproducts. • Not be liquids--they might be dendrimers impregnated into a solid structure. If the past is a guide, they may be something that we haven't yet conceived of. | O N | C LIQUIDS If you had been at Kitty Hawk, N.C. in December 1903, you might have witnessed the initial manned flight by the Wright brothers with a heavier-than-air craft. Had you done so, would you have telephoned and established a frequent flier account so you could earn a free trip to Hong Kong? Probably not. Would you have bought stock in firms providing transcontinenta] railroad service? Probably no.t either. That's where we are, almost, today with ionic liquids. Ionic liquids are organic salts with melting points under 100 °, often even lower than room ternperature. Recently, they are employed more and more as substitutes for the traditional organic solvents in chemical reactions. Most of the familiar cleaning agents (water, ethanol, www.metalfinishing.com
/
hexane, etc.) are molecular. That is, regardless of whether they are polar or nonpolar, they are basically constituted of molecules. Ionic liquids are different. They are composed of ions, not molecules. Ionic liquids are "designer solvents." The degree of flexibility is nearly infinite. Another author wrote: "If you look at j u s t the number of papers and patents in ionic liquids and plot that versus years, it's gone up exponentially." Researchers studying ionic liquids aren't certain of their intermolecular structure. In 2004, most believe that they remain liquid at room temperature because their ions don't pack together well. Combining bulky, asymmetrical cations with smaller, evenly shaped anions has been described as "like gluing an octopus to a basketball." This leaves the ions disorganized, without a regular s t r u c t u r e - - i n other words, in a liquid phase. O t h e r t h a n their chemical character, ionic liquids have a unique p r o p e r t y t h a t m a k e s t h e m of interest to those doing chemical cleaning. Ionic liquids don't evaporate. Ionic liquids aren't volatile. From the perspective of environmental management, that is an extremely good thing. All ionic cleaning agents would, supposedly, be VOC exempt in both the U.S. (unreactive with UV light) and in Europe (very high boiling), not contribute to global warming, and not be hazardous air pollutants (HAPs). That's not necessarily good news for those formulating solvent-based paints and coatings. After all, a wet solvent that doesn't e v a p o r a t e will produce a p a i n t or coating t h a t n e v e r d r i e s - - i t always runs. A w e t cleaning agent t h a t has to be removed by v a c u u m drying in February 2005
every application won't be popular among many. The major concern about ionic solvents for those interested in industrial cleaning is future availability. Parts cleaning is not a huge sales outlet for producers of chemicals. This leads to questions. Will there be any ionic solvents developed for cleaning? What range of solubility parameters will or can be available? Will the flexibility provided by oxygenated cleaning solvents be provided by a s p e c t r u m of ionic cleaning solvents? The minor concern about ionic solvents is price. Today no user could afford ionic solvents for cleaning, no m a t t e r to w h a t extent they can be recycled. As d e m a n d increases, prices will fall. It's not fair to presuppose that ionic solvents will be overly expensive--who would have proposed in 1903 that one could fly from New York to Miami for $100? But it is an open quest i o n - w i l l ionic solvents be affordable for cleaning work?
Circle 014 on reader information card or go to www.thro.to/webconnect
BIOLOGICAL SOLVENTS This technology, and associated products, are not true cleaning agents. Soils are not dissolved. R a t h e r t h e y are removed with biologically active s u r f a c t a n t s that are applied at room temperature and near-neutral pH. The cleaning solution cont a i n s n o n y l p h e n o l - f r e e surfactants. These t e n s i d e s act to r e d u c e t h e s u r f a c e t e n s i o n of water. W h e n p a r t s e n t e r t h e
Circle 020 on reader information card or go to www,thru,to/wehcongect
47
•
"
~
~.~{ ,~-~4~" e2"~-,,~-j.~,; ,.,,,~,,_ - %~.~ ~-.~.......... ~ y ~:~' ,,,,t,,,. '., '">,'-, '~'r,',,,
eral days). Consequently, this approach is not useful for cleaning parts with a high soil level. In this situation, the size of the oxidation tank can literally dwarf the size of the manufacturing unit. Please note that the soil does not have to be disposed when biological cleaning is used. The soil is oxidized to CO2 and H20. The only material to be disposed is a concentrate of expired organisms (sludge). Usually, the cleaning package of surfactants is not oxidized and can be recycled.
X
-;.
%
CLAR|FII©AT|@N Table
II1: C o m p a r i s o n
Figure 1'The structure of a general dendrimer
solution, tensides lift oil and impurities off the parts and emulsify them into microparticulates that are then consumed by microorganisms in the bath. The bacteria is safe for h u m a n contact and ]s comparable to that used in the food, dairy, and brewery industries. As the volume of oil increases, the organisms multiply in direct proportion, maintaining optimal cleaning power. The microorganisms become more effective as the oils emulsify. The oil-based soil is oxidized at a slow pace (sev-
i
Drying
Projected Instantaneous Costs as Energy Requirements-- K W 2 to 4
Air Blowoff
8 t o 22
Hot Forced Air
10 t o 3 0
The following table was inadvertently ommitted from page 52 of last month's column. John B. Durkee, H PhD, PE, ~s a consultant tn critical and metal cleaning with Creatwe EnterpriZes, a consulting ftrm ~n Hunt, Texas. You can contact the author at (e-mail) [email protected]; (phone) (830)-238-7610; (fax) (612)-677-3170. I#f
Systems that Set the Pace in Produ ,-t,,,,t,,
~
Projected
Centrifugal
GUYSON MULTI-BLAST ° ,
of
Costs
Drying Method
| _ ~
,,,,, ', ',
Automate your blasting process for consistent quahty results, control over component surfaces and lower production costs
SVST
TW..S
Phone 401-253-0050 Fax 401-253-1602 Webs,te www systinc c0m
Bathminder Brightener Feeder
.gayson.com [] [] [] []
Shot Peen Etch, Prep Deburr Strip
r~ Oescale [3 Clean [] Deflash [] Decorate
Circle 016 on reader information card or go to vvww.thru.to/webconnect 48
Circle 027 on reader reformation card or go to w w w thru to/webconnect www
metalfinishing.com