• Korean Chemical Engineering Research
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• v.44 no.5
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• pp.547-554
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• 2006

The overall objective of this research was to find out the role of rapid mixing conditions in the species of hydrolyzed Al(III) formed by Al(III) coagulants and to evaluate the distribution of hydrolyzed Al(III) species by coagulant dose and coagulation pH. When an Al(III) salt was added to water, monomeric Al(III), polymeric Al(III), precipitate Al(III) was formed by Al(III) hydrolysis. The method of hydrolyzed Al(III) species characterization analysis was based on timed spectrophotometer with ferron as a color developing reagent. The hydrolytic species were divided into monomer, polymer, precipitate from the reaction kinetics. And then, the color intensity for monomeric Al(III) was read 3 min after mixing. With standard Al solution containing monomeric Al(III) only, the Al-ferron color intensity slightly increased with until about 3 min. During the rapid mixing period, for purewater, formation of dissolved Al(III) (monomer and polymer) was similar to rapid mixing condition, but for raw water, the species of Al(III) hydrolysis showed different result. During the rapid mixing period, for high coagulant dose, Al-ferron reaction increases rapidly. The kinetic constants, Ka and Kb, derived from Al-ferron reaction. The kinetic constants followed very well the defined tendencies for coagulation condition. For pure water, when the rapid mixing time increased, the kinetic constants, Ka and Kb showed lower values. Also, for raw water, when the rapid mixing time increased, the kinetic constants, Ka and Kb showed lower values.

• Journal of Korean Society of Water and Wastewater
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• v.36 no.3
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• pp.177-186
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• 2022

In this study, newly improved Ferron assay test haved on timed spectrometry was used for the determination of hyolrolytic Al species presented in PACl coagulant. The color development reagent ferron was prepared by using conventional method and two newly developed methods. Then the ferron assay test was used to compare and analyze the distribution of Al(III) hydrolyzed species presented in the prepared PACl and alum. The preparing method of reagent A required an aging period of 7 days by adding a hydroxylamine hydroxide and a 1,10-phenanthroline monohydrate reagent, whereas the preparing method of reagent B was used as a coloring agent immediately without aging time. The regression analysis between UV absorbance and Al concentrations of conventional method and newly developed method of ferron reagents in low-concentration aluminum solutions and high-concentration aluminum solutions, showed the correlation coefficients of 0.999 or higher, as showing high correlations of conventional method and newly developed method. Applying Ferron assay test, Al species in the PACls and alum were classified as Ala(monomeric Al), Alb (polymeric Al), and Alc (colloidal and precipitated Al). Distribution of Al(III) hydrolyzed species according to the preparation of ferron colorimetric reagents was similar.