NUCLEATION KINETICS OF PENTAERYTHRITOL

The solubility and the primary nucleation kinetics of pentaerythritol (PE) at 98% and 94% purity in aqueous solution were investigated in th e range 20-80 degrees C, and the effect of adding 1% formaldehyde or 2 % formic acid was also examined. The solubility increases with decreas ing purity of the product and on adding the cited compounds to the sol ution. The nucleation kinetics exhibit high values of nucleation order , ranging from 32 to 10 for nucleation temperatures in the range 19-61 degrees C; that is, the generation of nuclei becomes significant only after exceeding a threshold value of supersaturation, which increases as the temperature decreases. The primary nucleation rate increases s trongly with the temperature, while it decreases on decreasing the pur ity of the product and on adding formaldehyde and formic acid to the s olution. The hypothesis is suggested that some impurities, accompanyin g the 'pure' product also and adsorbed more strongly at low than at hi gh temperature, may inhibit the growth rate of the solute aggregates t o nuclei size, thus depressing the nucleation kinetics.