• Journal of the Mineralogical Society of Korea
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• v.21 no.2
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• pp.117-127
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• 2008

The characteristics of phosphate adsorption-desorption on kaolinite was studied by batch adsorption experiments and detailed adsorbed state of phosphate on kaolinite surface was investigated using ATR-FTIR (Attenuated Total Reflectance-Fourier Transform Infrared) spectroscopy. The phosphorous contents were measured using UV-VIS-IR spectrophotometer with 820 nm wavelength. The adsorbed P was generally increased with increasing pH value in the range of pH 4 to pH 9, however it is not distinct. Moreover the adsorbed P was significantly changed with different initial phosphate concentration. The adsorption isotherms were well fitted with the Langmuir equation, Temkin equation, and Freundlich equation in descending order. The maximum Langmuir adsorption capacity of kaolinite KGa-2 is 232.5 ($204.1{\sim}256.5$) mg/kg and has very higher value than that of kaolinite KGa-1b. Most of adsorbed phosphate on kaolinite were not easily desorbed to aqueous solution, but might fixed on kaolinite surface. However it needs further research about the exact desorption experiment. It was impossible to recognize phosphorous adsorption bands on kaolinite in ATR-FTIR spectrum from kaolinite bands themselves, because the absorption peaks of phosphorous have very similar positions with those of kaolinite, and the intensities of the former were very weak in comparison with those of the latter.

• Journal of the Mineralogical Society of Korea
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• v.20 no.4
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• pp.327-337
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• 2007

Mineral compositions were determined using quantitative X-ray diffraction analysis on the three kinds of Youngdong illite consisting of white, yellow and refined yellow samples. Mean particle size and their size distribution patterns were measured by laser particle size analyzer. The characteristics of phosphate adsorption on illite were studied through batch adsorption experiments. The white illite has less illite content, but is finer than that of yellow. The refined yellow illite has more illite content and finer particle size compared with those of raw yellow illite. The adsorption rate of phosphate generally increases when the mass of illite increases, whereas adsorption quantity decreases with ascending pH. The phosphate adsorption usually increases with ascending illite content or descending particle size. Although the white illite has lower illite content than the yellow, the former has higher phosphate adsorption quantity than the latter. This can be ascribed to the fine particle size, high interlayer charge, and low substitution in tetrahedral site of white illite. The adsorption isotherms of white illite are well fitted with the Langmuir equation, however those of yellow one are better with Freundlich equation.

• Journal of the Mineralogical Society of Korea
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• v.19 no.4 s.50
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• pp.247-258
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• 2006

The characteristics of phosphate adsorption on kaolinite was studied by batch adsorption experiments. The phosphorous contents was measured using UV spectrometer with 820 nm wavelength. The experiment with changing reaction time revealed that fast P adsorption occurred within $0{\sim}12$ hour, whereas slow adsorption reaction began after 12 hour. The adsorption percentage depended on kaolinite amount in phosphate solution. Rotary-shaker enhanced the adsorption percentage up to $11{\sim}15%$. The phosphorous adsorption appears to be insensitive to change in the ionic strength of KCl between 0.01 M and 0.1 M. From this result, we can conclude that phosphate was adsorbed on kaolinite as inner-sphere complexes. However, the ionic strength increased to 1.0 M, adsorption decreased. It suggests that phosphate may be adsorbed as outer-sphere complexes. Phosphate adsorption decreased with increasing pH value, but it is not distinct. The adsorption isotherms were well fitted with the Langmuir equation.