Patent ID: 7229808

Claim:
A process for producing a siliceous layer capable of biomass immobilization and selectively cutting off macromolecules having a molecular weight higher than a selected threshold, comprising the steps of: a) supplying a gas flow of a gas carrier saturated by a mixture of (1) Si(OR) 4 , (2) R′Si(OR) 3 and (3) R′SiH(OR) 2 , wherein R and R′, equal to or different from each other, are alkyl and/or aryl groups, wherein said gas flow is prepared by bubbling the gas carrier into a liquid mixture of (1), (2) and (3) in a ratio of either (1) 65–79%, (2) 1–10%, (3) 20–25% v/v or (1) 53–70%, (2) 10–22%, (3) 15–25% v/v, at a temperature of from 20 to 180° C., and b) exposing a support comprising a biomass to the gas flow of step a), wherein said selected threshold of molecular weight is chosen in the range of between 10,000 Dalton and 150,000 Dalton and wherein the ratio of (1), (2) and (3) in step a) is chosen as a function of the molecular weight of the macromolecules to be cut off.