Method of Recovering Aqueous N-methylmorpholine-N-Oxide Solution Used in Production of Lyocell Fiber

Abstract

A method of recovering an aqueous N-methylmorpholine-N-oxide (NMMO) solution used in production of Lyocell fiber includes: decoloring the aqueous NMMO solution by mixing the same with activated carbon using an agitation blower and by alternately energizing and de-energizing the agitation blower to contact the activated carbon with the aqueous NMMO solution thoroughly in an energy-efficient manner; filtering the aqueous NMMO solution which has been decolored through coarse filtration followed by ultrafiltration to remove the activated carbon and impurities from the aqueous NMMO solution; and concentrating the aqueous NMMO solution which has been filtered using one of a mechanical vapor recompression evaporator and a triple effect evaporator to remove water from the aqueous NMMO solution.

Description

CROSS-REFERENCE TO RELATED APPLICATIONThis application claims priority of Taiwanese application no. 099107591, filed on Mar. 16, 2010.BACKGROUND OF THE INVENTION1. Field of the InventionThis invention relates to a method of recovering a solvent used in production of fiber, more particularly to a method of recovering an aqueous N-methylmorpholine-N-oxide solution used in production of Lyocell fiber.2. Description of the Related ArtLyocell fiber is made from natural cellulose. Consequently, waste products of Lyocell fiber are naturally decomposable and are environmentally friendly. Lyocell fiber has mechanical strength similar to that of synthetic fiber, a good draping property, a sufficient thickness, and nice hygroscopicity. Furthermore, Lyocell fiber is comfortable to touch, is easy to be dyed, can be easily blended with natural or synthetic fiber different from Lyocell fiber, and can be easily processed.Referring to FIG. 1, a conventional method of producing Lyocell fiber includes...

AI Technical Summary

Benefits of technology

Therefore, the object of the present invention is to provide a method of recovering an aqueous N-methylmorpholine-N-oxide (NMMO) solution used in production of Lyocell fiber to facilitate NMMO recovery and to enhance NMMO recovery efficiency.

According to this invention, a method of recovering an aqueous NMMO solution used in production of Lyocell fiber comprises: decoloring the aqueous NMMO solution by mixing the same with activated carbon using an agitation blower and by alternately energizing and de-energizing the agitation blower to contact the activated carbon with the aqueous NMMO solution thoroughly in an energy-efficient manner; filtering the aqueous NMMO solution which has been decolored through coarse filtration followed by ultrafiltration to remove the activated carbon and impurities from the aqueous NMMO solution; and concentrating the aqueous NMMO solution which has been filtered using one of a mechanical vapor recompression evaporator and a triple effect evaporator to remove water from the aqueous NMMO solution.

Problems solved by technology

However, the NMMO solvent is costly.

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