Electro-osmotic dewatering of high moisture flax stems

•High moisture flax stems were subjected to electro-osmotic dewatering.•Slightly charged stem water mixture was dehydrated by electro-osmosis.•Efficiency function of applied voltage, cylinder pressure and time of soaking.•Electro-osmotic permeability increased with increase in water removal.•Electro-osmotic permeability decreased with increase in applied voltage.

Retted flax stems contained high amounts of water from the pre-soaking and retting processes. Electro-osmotic dewatering was investigated as a pre-drying process for high-moisture flax stems using a bench electro-osmotic roller press. The various parameters affecting electroosmotic dewatering were cylinder pressure (1000 kPa–3000 kPa), applied voltage (12 V–36 V) and pre-soaking time of the flax stem (12 h–36 h). An experiment was designed using central composite design. From the experiments, a maximum of 38.34% of the total water contained in the stem was removed using 12 h soaking; 1000 kPa cylinder pressure and 36 V applied voltage during the electro-osmotic treatment. For a given soaking time, at 36 V with 3000 kPa cylinder pressure the maximum water removal occurred. The electro-osmotic permeability of the stems at various conditions was studied. In all the treatments, electro-osmotic permeability ranged between 3.32 × 10−5 m2 V−1 s−1 and 1.22 × 10−4 m2 V−1 s−1. Electro-osmotic permeability was found to increase with increasing water removal and decreased with increasing applied voltage.

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