抄録
Adsorption of two types of polyvinyl alcohol molecule (PVA) onto carbon black from their aqueous solution were investigated. In this study, two samples of PVA (acetate residue : 0.6 and 18.521.5mol%) were used. They were adsorbed onto carbon black at 20°, 30°, 40°C for 24 hours. In this experiment, accurate determination of PVA concentration in dilute solution (10-410-2%) is necessary. A colorimetric method based on color intensity of blue colored complex formed between PVA and iodine was examined therefor
From investigations, the following results and considerations were obtained.
(1) In determination of PVA concentration, addition quantity of iodine and boric acid, reaction time and temperature etc. had influence upon coloration. The optimum condition was as follows :
PVA (0.0010.1g/l) 10ml
Boric acid (38g/l) 15ml
Iodine (0.005N, I2 : KI=1 : 4 by weight) 2ml
at 5°C, for 48 hours.
The color produced in coloration reaction at this condition was very stable and a linear relation between the optical intensity of blue colored complex and the concentration of PVA was obtained.
(2) Equilibrium isotherms obtained from the adsorption of PVA onto carbon black showed a good agreement with Langmuir equation. From this result, Δμ°, ΔH° and ΔS° were estimated and the types of bonding between carbon black and PVA molecules were discussed. It was believed that hydrogen bonding mainly contributed to adsorption of PVA-I (acetate residue : 0.6mol%) and hydrophobic bonding, too, related to adsorption of PVA-II (acetate residue : 18.521.5mol%).
