You can use-Whatman 1 cellulose fibre filter paper - pyramid folded - diameter 125 mm- grade 1

Chitosan solution should be filtered via Büchner funnel with moist muslin cloth as the filter. Create a vacuum while filtration

For filtering chitosan solutions, it is recommended to use a filter with a pore size of 0.2 µm or smaller

One suitable filter for this purpose is a syringe filter with a 0.2 µm pore size, made of materials such as nylon, PVDF, or PTFE. These filters can effectively remove particles and aggregates from chitosan solutions without causing clogging or loss of chitosan

I have 0.2% Chitosan solution dissolved in 1% acetic acid and after filteration using 0.2 µm filter paper, small white particles perciptated I do not know what are these particles. This is the first time to encounter such problem upon filteration. Any idea about this ?