solvent property is shown in table 4 c table 4 c regenerated solvent solvent analysis method viscosity 30 u00b0 c 15 7 6 9 gb t265 centipoises color gt 5 2 colorimetry ph 7 6 7 8 u2014 water content in the 2 2 n butyl alcohol solvent ppm azeotropy hydrocarbon 1000 40 sy2128 content in the solvent ppm appearance brown light yellow u2014 continue operation u2014 1 u2014 time year change rate of the u2014 u00b1 5 u2014 feed m see table 5 c it is the same as embodiment 1 c except in that the solvent is dimethylsulfoxide used during the absorption the weight ratio of the water and the dimethylsulfoxide is 1 0 valve v 1 v 2 v 3 v 4 v 5 v 6 are set in between the settlement area 3 filtration area 4 and 5 if close v 2 v 5 other valves are open the water soluble solvent at the settlement area 3 mixed with water and pass the filtration area 4 and 5 the regenerated solvent is discharged at the outlet of the filtration 5 directly if close v 2 only other valves are open the water soluble solvent at the settlement area 3 mixed with water and must pass the filtration area 4 or pass filtration area 5 or get regenerated solvent at the outlet of filtration area 4 directly if v 2 v 5 are fully closed the regenerated solvent and the analysis result of the solvent property is shown in table 5 c table 5 c regenerated solvent solvent analysis method viscosity 30 u00b0 c 2 3 0 9 gb t265 centipoises color gt 5 2 colorimetry ph 7 2 7 5 u2014.