<p>Membranes formed by constituents of ultrafiltration feed solutions on a support structure are called dynamic membranes. Lignin has the ability to form a self-rejecting membrane potentially useful for separating lignin from pulping wastes.</p> <p>Lignin solutions and pulp mill wastes were circulated past support tubes at different operating conditions. A typical product flux was about 7 gal/ft²day with about 99% rejection. The effect of the feed solution concentration, the pore size of the support structure and the cross-flow velocity were small on the membrane performance. A temperature increase from 30ºC to 70ºC increased the product flux by 130%. A higher operating pressure increased the product flux only slightly above a critical pressure of about 80 psi. The product flux was highly dependent on the pH, being e.g. 30 gal/ft²day at pH2 and 7.5 gal/ftday at pH//.</p> <p>Some chemical additives, reported to alter liquid conformation, were tested and the best results were given by addition of formaldehyde. It increased the product flux at pH2 from 30 gal/ft²day to 42 gal/ft²day. A pretreatment of the carbon support tubes by hydrochloric acid improved the product flux from 6 gal/ft²day to 16 gal/ft²day but the beneficial effect, in this case, was time dependent.</p> / Master of Engineering (ME)
| Identifer | oai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/9019 |
| Date | 12 1900 |
| Creators | Horsti, Seppo Markku |
| Contributors | Benedek, Andrew, Chemical Engineering |
| Source Sets | McMaster University |
| Detected Language | English |
| Type | thesis |
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