[molecular weight: 180.16 and 150.13 (g mol–1), respectively],
probably due to their high diffusivity [11.2 and 10.6 (10–6 cm2 s–
1), respectively] and low Stokes diameter [0.438 and 0.463 (nm),
respectively] of furfural and HMF compared with glucose and
xylose [Diffusivity: 6.76 and 7.69 (10–6 cm2 s–1), respectively;
Stokes diameter: 0.73 and 0.638 (nm), respectively] even if they
are uncharged and exhibiting high pKa