Study On Treatment Process Of Methylation Liquid In Caffeine Industry

The methylation liquid produced in caffeine industry contains a mass of sodium methyl sulfate. Based on the methylation liquid of New Nuowei pharmaceutical Co., Ltd under Shijiazhuang Pharmaceutical Group, this paper carried out an integrated membrane route of Nanofiltration (NF)-Disc tube reverse osmosis (DTRO) for recycling these resources. In this paper, the effect of operation parameters on separate performance was investigated through experiments. Furthermore, the effect of running time on recovery rate of sodium methyl sulfate and the desired volume of additive dialfiltration solvent was studied through the theoretical simulation and analysis.In the nanofiltration desalination experiment, the effect of working pressure, flow capacity and temperature on the nanofiltration membrane flux and removal rate of different salt components was studied. The result shows that membrane flux grows gradually with the increases of working pressure, the removal rate of sodium sulfate rises when the working pressure is higher, but its concentration in the permeate liquid reaches a plateau at low values. By contrast, the permeate content of sodium methyl sulfate decreases on higher pressure. Higher flow capacity promotes penetration process of sodium methyl sulfate, in addition, there are less sodium sulfate and more sodium methyl sulfate in the permeate liquid and membrane flux ascends slightly. Temperature has no significant influence on removal rate of salt components, however permeate salt concentration and membrane flux go up steadily as temperature rises. The optimum operating conditions are 2.6MPa working pressure,8.0L/min flow capacity and 25℃ temperature. Under these conditions, the concentration of permeate sodium sulfate is 0.37g/L and the removal rate reaches 98%.By using the orthogonal experimental design, the effect of various factors and levels on the concentration process of disc-tube reverse osmosis was analyzed. It turns out that flow capacity has the greatest impact on concentration performance, which is followed by working pressure and temperature. The optimum operating conditions are 6.0MPa working pressure,5.4L/min flow capacity and 25℃ temperature. Through the NF-DTRO process, the concentration of sodium methyl sulfate in the concentrated liquid reaches 453.80g/LThrough the theoretical simulation and analysis, the correlation between technic index and running time in batch constant volume diafiltration process was studied. The concentration of sodium sulfate and sodium methyl sulfate in the concentrated liquid increases with time, And them are also the interval function of running time. Meanwhile the recovery rate of sodium methyl sulfate surges substantially, and then remains invariability. Considering the economy and environmental requirement, the best operate time of batch constant volume diafiltration is 5. In this condition, the concentration of permeate sodium methyl sulfate is 0.45g/L and its recovery rate is 99.928%.