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Qualitative and Quantitative Analysis of Water
Published in Sreedevi Upadhyayula, Amita Chaudhary, Advanced Materials and Technologies for Wastewater Treatment, 2021
The second method, based on electrochemistry principles, uses a digital pH meter and glass electrode coupled with a reference electrode. A glass electrode is a type of membrane electrode having a bulb made up of special glass. A gel layer is present both inside and outside of the glass bulb. Depending on the pH of the solution in which we dip the electrode, the H+ ions either diffuse out of the gel layer or diffuse into the gel layer.
Characterization of Particle Surface Charge
Published in Jacques Buffle, Herman P. van Leeuwen, Environmental Particles, 2019
In respect to question (1), the answer is a qualified “no”, if the glass electrode is calibrated in terms of [H+] by Gran titration45–47 of a solution whose ionic strength is controlled by a “swamping” background electrolyte (e.g., KCl) that also controls the ionic strength in the suspension, and if the reference electrode is immersed only in an overlying supernatant solution of the suspension during titration.44 With this method, liquid junction potentials created by particles, by dissolved species not in the calibrating solution, or by the added protons or hydroxide ions in the suspension should be minimized and the suspension effect5,48,49 should be obviated. If pH buffer solutions are used instead to calibrate a glass electrode in the presence of liquid junctions, or even if a reversible electrode assembly is used with account taken of the actual ionic strength of the supernatant solution, there is still a need to convert pH or emf values to [H+] by calculation, which cannot be done unambiguously.50 Moreover, under the best circumstances, electrometric pH cannot be measured more accurately than ±0.05,50 with a corresponding, amplified uncertainty in the calculated [H+], especially at pH ≤ 4. On the other hand, the use of a “swamping” background electrolyte, like KCl, may produce σH values that bear little relevance to the net proton surface charge density developed by the particles of interest in a natural aqueous environment.
Sensing pH for the Perfect Tomato
Published in Denise Wilson, Sensing the Perfect Tomato, 2019
The simplest pH sensors use litmus or pH indicators to generate color representations of pH at coarse resolutions (on the order of 1 pH unit or greater). The most common instruments for measuring pH use an electrochemical approach with a glass electrode that includes a stable reference solution to ensure high-resolution, accurate, and consistent measurements. A wide range of other pH sensors are also available commercially. They are based on an equally broad range of sensing strategies and have attributes that are not available in glass electrodes, pH indicators, or other traditional pH sensors. And, many are smaller than glass electrodes while providing comparable accuracy and resolution, thus making them more attractive for integration into the IOT.
Smart water management system for residential buildings in Saudi Arabia
Published in Journal of Applied Water Engineering and Research, 2022
Potential of Hydrogen (pH) is a numeric scale applied to indicate the basicity or acidity of an aqueous solution. pH measurement is important in water purification monitoring, which is performed using pH meters. The pH meter has a glass proton-sensitive electrode, which creates a potential corresponding to the pH of a solution with reference to a silver chloride or calomel electrode. The purpose of the reference electrode is to preserve a constant potential at any given temperature. The glass electrode, usually located at the tip of the pH probe, allows hydrogen ions in the solution being measured to diffuse into the outer layer of the glass, whereas larger ions remain in the solution. The hydrogen ions concentration difference between the outside and inside of the probe generates a very small current. Hence, this current is proportional to the concentration of hydrogen ions in the solution being measured with a potential, E, that can be written as where E0 is the standard electrode potential at hydrogen ion activity (aH+) = 1 mol/l, R is the gas constant, T is the temperature in Kelvin and F is the Faraday constant. Most pH sensors are designed to produce an output of 0 mV at 7.0 pH, with a slope, or sensitivity, of −59.16 mV/pH at 25 °C. The ideal pH level of drinking water varies between 6 and 8.5.
Green formulation, characterization, antifungal and biological safety evaluation of terbinafine HCl niosomes and niosomal gels manufactured by eco-friendly green method
Published in Journal of Biomaterials Science, Polymer Edition, 2022
Katayoun Morteza-Semnani, Majid Saeedi, Jafar Akbari, Shakiba Hedayati, Seyyed Mohammad Hassan Hashemi, Seyyed Mobin Rahimnia, Amirhossein Babaei, Mona Ghazanfari, Iman Haghani, Mohammad Taghi Hedayati
The pH of the terbinasome 2 gel and terbinasome 3 gel formulations were measured using a digital pH meter (MS Tecnopon equip. Special LTDA). The 1 g terbinasome 2 gel and terbinasome 3 gel (was dispersed in deionized water (25 mL), and the pH was measured. The glass electrode was calibrated utilizing the equipment's solutions (pH of 4.00 and 7.00). The pH of the preparations were tested three times and the average value was reported.