Dear can anyone share the protocol for synthesis of filter papers from cellulose. How pore size can be controlled.
Hello Mr. Zia
companies like Hahnemühle, Macherey-Nagel or Whatman process for ex. purified linters pulp and Lyocel viscose in a wet milling step for almost ash-free paper. The pulp is adjusted to specific beating degree (°SR, Canadian Freeness). Addition of glass fibers or ARBOCEL Cellulose granules from JRS to achieve a less compressible structure. Pulp dewatering is tested by Britt Dynamic Jar, dosage and grammature by Rapid Köthen or Pilot Paper machine. Depending on the final apllication wet strenght additives, cationic and duroplastic resins can be added. Functionality test (Bayferrox iron oxide pigment, microorganisms, ..) to evaluate the beta-ratio. The drying is a critical step, in lab-scale dewatering to 50-60 % solid content and vacuum drying at 40 - 70 °C is the best choice. Cationic zeta potential of the pulp for higher wet density and higher clarification effect. Pore size distribution should be checked using light microscope or REM.
There is no easy relation between milling degree and pore size.
Dear Ralf
Thanks for detailed reply. I followed simple protocol as cellulose isolated from citrus peel was spread, pressed by ruler and dried by hot hair. Unfortunatly that paper was quite heard and resistant to filtration. Of course we do not have paper machnie at lab scale so can we adopt squeezing for paper formation. In few reports people used PEG 400 for pore size; normally it is used or something else as alternative?
Thanks again for helpfull discussion
Rgards
Citrus Peel fiber contains traces of pectin and soluble hydrocolloids, therefore use of cotton linters or wood cellulose pulp is better choice for filter sheets. In small Lab scale use equipment like Waring Blender for 5 min (homogenisation), then dewatering on Buchner funnel/PP fabric (80 µm pore size), 0,5 bar vacuum for 30 min., then drying at room temperature overnight between two softwood pulp tissue sheets; low molecular PEG for pore size, is washed out and prevents bone-dry hardening of the cellulose. But it is not easy to achieve the correct porosity and grammature.
For porosity < 5 µm there are well-defined Polyethersulfon PES Membran Filters available from the market.
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