Electro-osmotic dewatering of soaked hemp stems

ABSTRACT

Hemp stems were immersed in water as a pretreatment to enhance the production of hemp fiber. To reduce the high moisture content, the soaked hemp stems were dewatered using a bench-type electro-osmotic roller press. Variables like applied voltage (12, 24, and 36 V), roller pressure (1000, 2000, and 3000 kPa), and duration of soaking of hemp stems (12, 24, and 36 h) were subjected to investigation and the percentage of total water expelled due to electro-osmotic dewatering (EOD) at various levels of experiments was recorded. Hemp stems soaked for 24 h treated at a roller pressure of 2,000 kPa at an applied voltage of 36 V showed the maximum water removal after EOD process. The water removal was found to be increasing with increase in applied voltage and roller pressure. Soaking time up to 32 h leads to an increase in water removal and then it started decreasing. The probable reason for that was the penetration of surface water into micropores and its adhesion to the lignocellulosic bonds. Electro-osmotic permeability of hemp stems at various levels of voltages, roller pressures, and soaking times was studied and the result proved that electro-osmotic permeability was inversely proportional to applied voltage and it was independent of the applied pressure.

KEYWORDS:

• Electro-osmotic dewatering
• hemp stems
• natural fiber
• osmotic dehydration