Calcium ion test and pretreatment of raw flax

To improve conventional processing method,calcium ion content in raw flax was tested.The results indicate that more than 97% of calcium ions lie in pectin,which affect retting greatly.Therefore,pretreatment of raw flax was performed with selected chelating agents such as ethylene diamine tetraacetic acid,sodium tripolyphosphate,oxalic acid and ammonium oxalate.It is found that the effects of elhylene diamine tetraacetic acid,sodium tripolyphosphate,oxalic acid are not satisfactory,and changes of temperature and concentration can not separate the bast from stalk.However,ammonium oxalate is an effective chelating agent which can separate the bast from stalk under conditions of concentration 5 g/L,at 62℃for 5 h.