Ionic liquid treatment for increasing the wet strength of cellulose paper

In this study, ionic liquid treatment for increasing the wet strength of cellulose paper was studied. The effects of treatment conditions with the ionic liquid 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) on the wet strength were investigated. First, the [BMIM]Cl (20 g) was melted at 80–100 °C and the paper was immersed in it for 5–60 s. Next, the paper was immersed in ethanol, and finally, it was washed with distilled water. The paper was dried in a hot press at 110 °C and 1.1 MPa for 5 min. The [BMIM]Cl treatment improved the wet strength of the paper. Disintegration of the papers was investigated by immersing them in distilled water, and the paper treated with [BMIM]Cl did not disintegrate. The minimum treatment time required for improvement of the wet strength of the paper was only 5 s. Excess [BMIM]Cl from the original treatment was recovered by vacuum distillation and dehydration was used to treat new paper. This recovered [BMIM]Cl enhanced the wet strength to a level similar to that obtained with the virgin [BMIM]Cl. Therefore, the [BMIM]Cl can be efficiently re-used in this method. The paper treated with [BMIM]Cl will be composed completely of cellulose. Therefore, this method is a viable alternative to treatment by adding chemical such as a polyamideamine epichlorohydrin (PAE).