Cross-linking of what? Glutaraldehyde cross linking of proteins is usually done at pH7.5~8, Phosphate or HEPES buffer, avoid TRIS.

Do note that is commonly accepted that Glutaraldehyde interact mainly with primary amines, so it is unlikely to react with cellulose. See here:

Migneaul et al (2004) Glutaraldehyde: behavior in aqueous solution, reaction with proteins, and application to enzyme crosslinking. BioTechniques 37:790-802.