1. College of Chemistry and Chemical Engineering, Hunan University, Changsha 410082, Hunan, P. R. China
2. School of Chemical Engineering, Zhengzhou University, Zhengzhou, 450001, P. R. China
3. Institute of Bast Fiber Crops, Chinese Academy of Agricultural Sciences, Changsha 410205, Hunan, P. R. China
4. College of Chemistry and Chemical Engineering, Central South University, Changsha 410083, Hunan, P. R. China