| 摘要 |
<p>During nanocrystalline cellulose (NCC) production, a considerable amount of sulphuric acid is used. After the separation of the NCC, the remaining solution contains sugars and residual sulphuric acid. The sugars are in the monomeric and oligomeric forms. To reduce the cost of NCC production and to produce other added-value products, the spent acid stream can be fractionated into sugar oligomers, sugar monomers, and acid. The acid can be recycled to the NCC manufacturing process after concentration. The sugar monomers and sugar oligomers can be used for the manufacturing of other valuable chemicals. Membrane nanofiltration can be used to achieve this objective. A polymeric membrane with a molecular weight cut-off in the range of 200 Dalton was employed. Using this approach, the majority of the acid was recovered in the permeate while the sugars were concentrated in a smaller stream. The sugar level in the separated acid/permeate stream was only about 3% of the original concentration. A second membrane filtration stage can be used to separate the monomeric from the oligomeric sugars. The two sugar streams can be employed in different applications to produce value-added products.</p> |
