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vol. 16, nr. 2 (2010)
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Optimalization of potentiometric titration process of humic acids in presence of strong buffering substances
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Patrycja Boguta, Zofia Sokołowska
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Institute of Agrophysics, Polish Academy of Sciences Doświadczalna 4, 20-290 Lublin 27, Poland |
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vol. 16 (2010), nr. 2,
pp. 243-253
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abstract:
. Main object of study was to find out optimal conditions for potentiometric titration of humic acids in presence of strong-buffering substances. Studies were carried out for commercial humic acids sample (Aldrich HA). Phosphates (V) ions were used as strong buffering substance. In case of optimalization of potentiometric titration, both sample preparation and technical parameters were studied. Suspensions of humic acids were prepared in concentration 50 and 500 ppm. Phosphates concentration was established at (0, 600, 1500, 3500 and 7000 ppm). Volume step of titrant was set on 0,1 and 0,01 ml as well as value of potential drift was estabilished at 10 and 70mV/min. Studies showed that titration rate should not be constant for all range of pH. Potential drift value was main parameter which decided about quality of obtained relationships. Low value of this parameter caused that titration process was slower but sorption of CO2 was greater what was visible on the relationships of calculated apparent surface dissociation constant. Higher concentration of humic acids and smaller volume step of titrant let obtain potentiometric titration curves with lower level of noises.
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keywords:
potentiometric titration, humic acids, buffer substances
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original in:
Polish
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