Determination of Fluoride in Water. A Modified Zirconium-Alizarin Method

Comparison and understanding of fluoride removal mechanism in Ca2+, Mg2+ and Al3+ ion assisted electrocoagulation process using Fe and Al electrodes

“…Prior to the start of electrolysis, electrolyte solution was stirred magnetically at a constant rate of 300 rpm. The fluoride concentration in bulk solution was estimated by UV-vis spectrophotometer (JASCO V-670) using zirconium-alizarin standard method [35,36] and it denoted as initial fluoride concentration (C i ). After electrolysis, electro-coagulated solution was stirred for 45 min to ensure the fluoride adsorption/desorption equilibrium and then, the solution was allowed to settle for 2 h. Finally, the residual solution was filtered through 0.22 mm Whatmann membrane filter papers.…”

Factors Affecting the Determination of Fluoride in Water With Zirconium‐Alizarin

“…Reagents. These are: [11 sodium hydroxide pellets; [2] sulfuric acid, concentrated; [3] silver sulfate powder; and [4] phenolphthalein indicator. (D) is released and air pressure is applied to the tube (A).…”

“…Ratio mg fluoride;[2] for 1 hr readings when the phosphate does not exceed 0.20 mg, the error is not more than 0.007 mg fluoride; and[3] for 7-18 hr readings when the phosphate does not exceed 0.20 mg, the error is not more than 0.004 mg fluoride. If the concentration of phosphate in the sample aliquot exceeds these limits, the fluoride should be isolated by distillation.…”

Report of the Committee on Water Supply

“…It is believed that this is an opportune time to state the objective of this committee, namely: safer water supplies. To this end, the committee is devoting its attention to the following: 1 There is a lag between the development and refinement of technical processes, laboratory technique, etc., and their application in the routine treatment and supervision of public water supplies. This is emphasized by the present status of chlorination for the production of free residual chlorine; that is, superchlorination or break-point chlorination.…”

“…In spite of the extensive literature upon the subject and in spite of the rather numerous supplies which are being subject to free residual chlorination, there is still a reluctance on the part of many water supply officials to avail themselves of this treatment process. It seems pertinent, therefore, to focus attention upon the fact that the use of chlorine doses sufficient to give free residual chlorine rather than combined residual chlorine (chloramines) will result in the following advantages: 1 [555]…”