Filtration of Cellulosic material - the impact of ionic strength and electric field
Licentiate thesis, 2021
The work presented in this thesis examines the filtration of cellulosic material in the form of microcrystalline cellulose (MCC) and microfibrillated cellulose (MFC). The influence of ionic strength on the dead-end filtration of MCC was investigated by the addition of NaCl in the range of 0-1 g/L. It was concluded that increasing the ionic strength improved the filtration rate: the surface charges of the MCC particles were shielded which, in turn, promoted agglomeration and reduced the total surface area subjected to the liquid flow. This confirms the importance of electrostatic interactions between MCC particles during dead-end filtration.
The MFC was produced via 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO)-mediated oxidation and an electro-assisted filtration technique was employed to dewater the suspension. Compared to conventional dead-end filtration, electro-assisted filtration significantly improved the dewatering rate due to the electrokinetic phenomena it introduced. Three different levels of electric field were used, and it was observed that the dewatering rate increased proportionally to the strength of the electric field. In addition, molecular dynamic (MD) simulations were performed to obtain an understanding of the dewatering mechanism on a molecular level.
Chalmers, Chemistry and Chemical Engineering, Chemical Technology, Forest Products and Chemical Engineering
Dewatering microcrystalline cellulose: The influence of ionic strength
Separation and Purification Technology,; Vol. 264(2021)
Karna, N, Lidén, A , Wohlert, J, Theliander, H. Electro-assisted filtration of microfibrillated cellulose: Insights gained from experimental and simulation studies
Lokala egenskaper vid kakfiltrering: Inverkan av ett elektiskt fält
Swedish Research Council (VR) (2017-04521), 2018-01-01 -- 2021-12-31.
Paper, Pulp and Fiber Technology
Chalmers University of Technology