Assessment of enzymatic treatment and ultrasonication of wood and old corrugated container pulp as an alternative to refining
Stander, Werner Heinz
MetadataShow full item record
The effect of ultrasonication and enzymatic treatment on paper pulp was investigated as an alternative to conventional refining. The present study focused on three specific pulp types: Hardwood (Eucalpytus globulus), softwood (Pinus radiata) and recycled (old corrugated containers or OCC) pulps. The pilot-scale experiments were done using a single-disk refiner and Hielscher UID1000 ultrasonicator. Within each experiment, enzymatic treatment and ultrasonication amplitudes were varied. Endoglucanase was used for enzymatic treatment, and dosages as well as the sequences of treatments varied. The freeness of the pulp and the strength properties of the paper sheets made from the pulp were tested for each of the treatment combinations. Ultrasonication was effective in modifying the pulp fibres at low energies (between 0 and 20 kWh/t). The stronger softwood fibres seemed to be effectively modified by ultrasonication. The strength properties of the hardwood and recycled fibres, however, could not be developed using ultrasonication without seriously affecting the freeness of the pulp. It seemed that ultrasonication at low to medium amplitudes (53 μm and 80 μm) was most effective in developing the hardwood and OCC fibres. Ultrasonication at medium to high amplitudes was most effective in developing the softwood fibres. The combination of low enzymatic dosage and ultrasonication appeared to increase the tensile strength and the tear strength of the fibres more than ultrasonication on its own. The added enzymatic treatment did not, however, counter the decrease in freeness as expected. High enzymatic dosage (200 g/t) seemed to result in higher strength and freeness results at low energies (0 to10 kWh/t). At higher energies, however, the strength and freeness results were similar when compared to the low enzymatic dosage (50 g/t) treatment. When the pulp was enzymatically treated after ultrasonication, there was no strength benefit, but the pulp freeness seemed to have increased. Ultrasonication and enzymatic treatment seemed to be the most effective when treating softwood fibres. The reason may be that the softwood fibres were stronger than the hardwood and OCC fibres and were efficiently modified by the longer treatment times. Ultrasonication did not appear to be a viable alternative to mechanical refining, due to the notably longer treatment times required to modify the fibres and the severe freeness decrease compared to mechanical refining. Ultrasonication may be considered as an effective pre-treatment for mechanical refining to limit the energy used.
- Engineering