Below is an article I recently came recently across in relation to cleaning products and the chemistry behind it. This may not answer your question but I will submit a more detailed post on Monday.
Many technologies that separate known constituents, such as spent cleaner and rinsewater, at known constant concentrations from each other in a feed stream are available on the market
today. These separation processes may be effective for large volumes. Low volume and highly variable content streams are not likely to be cost effective applications for these separation processes.
Process data from a variety of cleaning operations reveals that the type and quantity of soils, contaminants, and cleaning solution concentrations can vary on the same part in the same facility and in the same cleaning process from day to day. These variations can easily exceed 50% and even reach 90%. Most failed attempts at extending cleaning solution bath life have resulted from failures to recognize the highly variable dynamics of real world cleaning processes.
The basic premise used to develop the process introduced here has six steps: They are:
[indent]Step 1: Redesign the cleaning process and chemistry so as to eliminate the need for any waste disposal.
Step 2: Make sure any “waste” produced is a designer waste designed to be a product itself and not a waste.
Step3: Redesign the process to reduce the waste volume of any waste to be produced.
Step 4: Redesign the process to reduce or eliminate the toxicity of any waste produced.
Step 5: Consider ways of applying new technologies with old technologies in ways that were not previously possible or economical.
Step 6: Consider opportunities made available by Step 5 for miniaturizing and automating large-scale proven processes.
[/indent]This new process is based on on-site reaction chemistry. Instead of trying to selectively separate the organic contaminants from the cleaning solution, which would result in the creation of a new waste stream, the process uses a limited amount of reagent (primarily ozone) to chemically convert organic contaminants. These reaction products are less or non-hazardous compounds that also function as useful cleaning agents. As organic contaminants are dragged into the cleaner and converted, the ability of the system to clean and emulsify contaminants actually increases for a period of time. For systems with overflowing rinses, the drag-out of cleaning agents eventually equals the creation of cleaning agents from the drag-in of organic contaminants.
One of the advantages of this approach is its lack of dependence on separation efficiency. Another is its lack of dependence on non-emulsifying aqueous cleaner chemistry to achieve optimum performance. Many new environmentally friendly stamping and machining fluids are highly water soluble oil emulsions. Non-emulsifying oil splitting cleaning formulas may not split as effectively when water-soluble oils are being removed from the parts.
Cleaning Chemistry Manipulation
In order to understand the chemistry behind the process that turns spent cleaner contaminates into usable cleaning agents, it is useful to briefly explore some of the chemistry behind cleaning. Cleaning processes depend on one or a combination of three basic processes: [LIST=1][LIST=1]
A dissolving action (absorption and dilution effect such as an organic solvent dissolving an oil)
A mechanical action, such as abrasive surface cleaning or spray agitation.
A surface active action whereby soils are de-sorbed (the reverse of adsorption) from the part surfaces with the aid of surface active agents. Combinations of these three are frequently used.Elevated temperatures are used to lower soil viscosity, increase saponification rates, increase transport rates of surfactant migration to part soil interfaces, and to lower the surface tension of water-based cleaning products. Increased mechanical pressure is used to increase mechanical action removal rates. The only remaining control variable beyond temperature and pressure manipulation is cleaning agent chemistry manipulation. Cleaning chemistry manipulation is assumed to include any reactive chemistries and solid abrasive compounds for the purpose of this discussion.
Aqueous cleaners also depend on additives that sequester hard water ions so that they stay in solution at concentrations beyond their normal solubility and do not precipitate on the parts being cleaned. Chelating agents keep metal ions, like iron that has been removed from parts, from plating back out of solution on to parts as a black iron oxide smut. Wetting agents reduce the surface tension of the cleaning solution to increase cleaner wetting action on the part to be cleaned. They can also reduce the dynamic (time-dependent) surface tension of the cleaning solution. Solubilizers increase the solubility of certain species in the cleaning agent.
Ethylene glycol butyl ether, which is soluble in water and oil, is an example of a solubilizing agent. By adding "butyl" to water, one can increase the solubility of oil in water. Emulsifiers increase the capacity of a cleaner to emulsify non-soluble compounds in the cleaner. Anionic soap surfactants are an example of an emulsifying agent (as opposed to a solubilizing agent).
Many cleaning compound agents perform several functions at once. Butyl, for instance, can serve as a wetting or surface tension reducing agent as well as a solubilizing agent. It also can contribute to emulsifying capabilities when combined with anionic surfactants or soaps (alkali-metal salts of carboxylic acids).