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Water Quality Parameters
Published in Joseph Cotruvo, Drinking Water Quality and Contaminants Guidebook, 2019
The other commonly noticeable effect of calcium and magnesium and related ions in water is that they react with soap that is a large fatty acid molecule (e.g., a stearate) and form the insoluble metal salt (e.g., calcium stearate) that deposits as soap scum or bathtub ring. These various precipitates from water are not easily removed, and may require an acid wash to clean them from showerheads, faucet aerators, and surfaces. Detergents for clothes washing, dishwashing, and shampoos are formulated for specific purposes and are much less affected by hard water because they are structurally and chemically different from soaps. So, water hardness is at least an annoyance, but that can be overcome. It certainly can have major economic consequences in the home and also for industry.
Stability and Coagulation of Colloidal Suspensions
Published in James F. Pankow, Aquatic Chemistry Concepts, 2018
Direct hydrogen bonding between lyophilic particles and water makes colloidal suspensions of such materials permanently stable, and the rate of particle coagulation will be zero. Colloidal suspensions of lyophobic particles are, on the other hand inherently unstable, and the rate of coagulation will always be greater than zero. Indeed, if brought sufficiently close together by a mechanism such as Brownian diffusion (see Figure 27.1a), lyophobic particles will stick together and squeeze out much of the intervening aqueous phase. If one desires to coagulate lyophilic particles, it will first be necessary to convert them to lyophobic particles. In the case of proteins, this can be accomplished by denaturing the protein with heat. In the case of humic materials, it can be accomplished by adding either some strong acid, or a solution of a di- or trivalent metal ion. Strong acid protonates the carboxylate and phenolate groups that provide humic material with its hydrophilicity. This makes the large molecules of humic material much more hydrophobic and much less soluble. Indeed, the standard method for isolating “humic acid” involves lowering the pH. A di- or trivalent metal ion will also react with carboxylate and phenolate groups, again making the humic material more hydrophobic by virtue of conversion to a rather insoluble metal-humate complex. This precipitation of humic acid by metal ions is exactly analogous to the precipitation of soaps (and the formation of soap scum) by the Ca2 + and Mg2 + that is found in hard water.
Filtration Systems for Metalworking Fluids
Published in Jerry P. Byers, Metalworking Fluids, Third Edition, 2018
Other removal units available work on the difference in specific gravity between the oil and metalworking fluid. These devices are centrifugal, and were originally designed for the removal of one fluid from another. The separation process takes place under varying amounts of relative centrifugal gravities. These can be low or high depending on the equipment purchased. The low-speed units do not subject the metalworking fluid to high gravity forces and therefore separate the free oil with less retention time than would be required under normal gravity conditions. The higher-speed units can subject the metalworking fluid to very high forces. These forces can be high enough to separate not only the free oil but also the metalworking product itself. Besides the possible deleterious effect on the fluid, these units tend to require more maintenance and a higher degree of technical support. All of the units will tend to remove some material that can form in the metalworking fluid other than free oil. These consist of invert emulsions, soap scum, hard-water precipitates, and fine particulate.
The nexus between alternatives assessment and green chemistry: supporting the development and adoption of safer chemicals
Published in Green Chemistry Letters and Reviews, 2021
Joel A. Tickner, Rachel V. Simon, Molly Jacobs, Lindsey D. Pollard, Saskia K. van Bergen
During laboratory evaluations, Omnia™ outperformed the other solvents on an assortment of soil types – greasy dirt, tar, and soap scum – from a variety of substrates visually achieving 100% cleaning efficacy first, while the other solvent-based formulations remained soiled. Somewhat unique to this product, is its effectiveness in cleaning both polar (hard water stains and rust) and non-polar (oil, wax, and grease) soils. This property makes it useful in general-purpose cleaning products, allowing formulators to reduce SKUs and the final users such as cleaning staff to need fewer product types. (E) Economic attributes