I have nonporous silica particles with a size of 400 nm and a BET surface area of 10.4 m2/g (mode of pore size 1.87 nm). I measured the weight loss during TG analysis and it was 0.93% (second step of the thermograph which corresponds to dehydroxylation of the particles at a temperature higher than 130 deg C). Using the weight loss and BET surface area, the value of the density of silanol groups is about 60 micromol/m2. The Zhuravlev constant for a fully hydroxylated silica surface is 8 micromol/m2. Any sample should have a value equal or less than 8, why the value obtained for my sample is higher than 8 micromol/m2. I really appreaciate your assistance. Thank you