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Water Treatment
Published in Carl Bozzuto, Boiler Operator's Handbook, 2021
There are two basic ways that corrosion occurs in a boiler and an additional one for condensate systems and piping. As the number of hydrogen ions in water increases, the pH gets lower. The free hydrogen ions attack the metal in the boiler, changing places with the iron molecules in the steel. Preventing this kind of corrosion is solved by adding hydroxyl ions to the water to combine with the hydrogen ions, making water molecules. This greatly reduces the number of hydrogen ions and they cannot attack the iron. The chemical normally added to boiler water to raise the pH (which means fewer hydrogen ions) is sodium hydroxide (NaOH). Ammonia has also been used. It is easy to envision that chemical dissolving into sodium (Na+) and hydroxyl (OH-) ions in the water. Enough is added to keep the pH of the boiler water in the range of 9-10. Adding too much caustic soda will raise the pH so high that other problems, caustic embrittlement and caustic cracking, will occur. In some localities, the water is already alkaline. Additions of caustic soda are not required. Some of those actually require additional blowdown to prevent the pH from going too high. When there is a problem with caustic water or high pH, be very careful of leaks in the boiler. Evaporating water leaves a concentrated solution, where the pH is way too high. Severe damage to the boiler near the leak can result. The damage is said to be the result of caustic embrittlement.
The Groundwater Geochemical System
Published in William J. Deutsch, Groundwater Geochemistry, 2020
The acidity of water is a function of the concentration of dissolved species that can contribute a hydrogen ion to solution to consume hydroxyl ions added during the acidity titration. The acidity can be defined similarly to alkalinity as follows: () Acidity(meq/L)=2mH2CO3+mHCO3−+morganic acids+2mH2S+mHS−+mH+−mOH−
Superficial deposits
Published in A.C. McLean, C. D. Gribble, Geology for Civil Engineers, 2017
An important factor governing the type of chemical reaction that will take place in weathering is the pH value of the local environment within the rock. The pH is related inversely to the concentration of hydrogen ions present in any water. A neutral environment has a pH of 7.0, whereas a pH of 6.0, with a hydrogen ion concentration ten times as great, is acidic. A pH of 8.0 has one-tenth the concentration of hydrogen ions as pH 7.0, and is alkaline.
Preparation of green synthesized copper oxide nanoparticles for efficient removal of lead from wastewaters
Published in International Journal of Phytoremediation, 2021
Amir Zarrabi, Reza Ghasemi-Fasaei
The effect of solution pH on the adsorption rate is shown in Figure 10. According to this figure, the amount of Pb adsorption by all three synthesized nanoparticles increased by increasing pH of the solution. Increasing pH causes the decrease of hydrogen ions in the solution. The reduction of hydrogen ions produces negative charges due to the creation of lone electron pair in the oxygen of CuO and absorbs divalent positive Pb ions (Azizi et al. 2017). This effect was stronger at higher pHs and resulted in the highest removal efficiencies at pH 11. Figure 10 also confirms that the highest and lowest REs belonged to the A-CuO-NPs and M-CuO-NPs, respectively. In addition, the increase in RE with the increase in pH in the M-CuO-NPs is more regular than that of the other two nanoparticles.
Effects of use of alkaline mixing waters on engineering properties of cement mortars
Published in European Journal of Environmental and Civil Engineering, 2018
pH concept was developed for determining the strength of acid or base. The acidity or alkalinity degree of an environment depends on the H+ and OH− ions in the environment. As is known, in water and in all aqueous solutions (at 25 °C [H+] [OH−] = 1 × 10−14), the molar concentrations of H+ and OH− ion concentrations in water and aqueous solutions have very low values. In order to remove the difficulty of dealing with these small numbers, pH and pOH concepts were created. The pH of a solution is the negative logarithm (to the base 10) of hydrogen ion molar concentration of a solution (Biryol, 1995; Orbey et al., 2012).
Exploring the role of biopolymers and surfactants on the electrical conductivity of water-based CuO, Fe3O4, and hybrid nanofluids
Published in Journal of Dispersion Science and Technology, 2023
Nikhil S. Mane, Vadiraj Hemadri, Siddhartha Tripathi
Figure 2 shows that the nanofluids with SDBS have higher pH than nanofluids with biopolymers. When dissolved in water, the chitosan and GA biopolymers show a pH lower than 7. Nanofluids prepared with SDBS are basic, while nanofluids prepared with chitosan and GA are slightly acidic. The pH is inversely proportional to the hydrogen ion concentration in the fluid; therefore an increase or decrease in the pH with dispersant concentration shows a change in hydrogen ion concentration and activity. As SDBS is a ionic surfactant, its addition increases the concentration of SDBS ions in the water. As a result of their interactions with the hydrogen ions in water, these SDBS ions increase pH while decreasing the hydrogen ion concentration.[35]