Ｎ，Ｎ‐ジメチルアセトアミド水溶液の逆浸透濃縮

Abstract

Reverse osmotic concentration of aqueous N, N-dimethylacetamide solutions was carried out, using cellulose acetate asymmetric membranes and composite membranes : PEC-1000, NS-100 and FT-30. Separation of N, N-dimethylacetamide and solution flux through the membranes were measured in the following ranges : concentrations, 1 to 7 wt%, operating pressures, 2.94 to 6.86MPa. PEC-1000 membranes show the best performance among the membranes tested. Its separation was above 99.5% and the best was 99.95% at 1wt%, 7MPa. At the same experimental condition, separation of FT-30 BW was 92%, FT-30 SW 94%, NS-100 P 1700 86%, NS-100 P 3500 95%, CA heat treated at 90°C 93%, 87°C 74%, and 85°C 76%.An analysis of data with Spiegler-Kedem's transport model was carried out to obtain membrane constants such as reflection coefficient σ, solute and hydraulic permeabilities w and Lp, and concentration induced compaction coefficients for ω and Lp, βs and βv, . Values of a for PEC-1000 are 1.0. FT-30 shows the largest value of βv, and cellulose acetates are the smallest.Energy and membrane area required using PEC-1000 were calculated to concentrate aqueous N, N-dimethylacetamide solution from 0.6wt% to 5.1wt% and 9.7wt% by reverse osmosis. The energy per kilogram of concentrated N, N-dimethylacetamide is proportional to operating pressure and slightly depends on final concentration and concentration polarization, and is found 0.25 to 0.55 kwh /kg-DMAc. The membrane area is inversely proportional to the operating pressure and found 0.52 m2/kg-DM Ac/day to concentrate upto 9.7wt%, at 5 MPa, and no concentration polarization.