a. pH Sensor “The term pH is derived from a combination of “p” for the word power and “H” for the symbol of the element Hydrogen. Together the meaning is the power of hydrogen. pH used to compare the relative acidity or alkalinity of a solution at a given temperature. A pH of (7.00) describes a neutral solution because the activities of hydrogen and hydroxide ions are equal. When the pH is below (7.00), the solution is described as acidic because the activity of hydrogen ion is greater than that of hydroxide ion. A solution is more acidic as the hydrogen ion activity increases and the pH value decreases. Conversely, when the pH is above (7.00), the solution is described as alkaline because of the activity of hydroxide ion is greater than …show more content…
Amperometric Free Chlorine Sensor
• Free Chlorine Definition When chlorine solution is added to drinking water, it takings through a series of reactions described in the flowchart of figure (2.12). Fig. (2.12) Chlorine Addition Flow Chart [35] When chlorine is added to water, some of the chlorine reacts first with inorganic and organic materials and metals in the water and is not available for disinfection (this is called chlorine demand of the water). After the chlorine demand is met, the remaining chlorine is called total chlorine. Total chlorine is further divided into: [35]
i. Combined chlorine, which is the amount of chlorine that has reacted with inorganic (nitrates, etc.) and organic nitrogen-containing molecules (urea, etc.) to make weak disinfectants that are unavailable for disinfection. ii. Free chlorine, which is the chlorine that is left over and is available to inactivate disease-causing organisms; it is a measure of the potability of the water. Free chlorine chemically refers to hypochlorous acid (HOCl) and the hypochlorite (OCl–) ion [36].
• Sensorex FCL Free Chlorine