1. State Key Laboratory of High-efficiency Coal Utilization and Green Chemical Engineering, and Key Laboratory of Ningxia for Photovoltaic Materials, Ningxia University, Yin-Chuan, Ningxia, P. R. China;
2. Huineng Middle School, Xinxing County, Yunfu, Guangdong, P. R. China;
3. College of Materials and Environmental Engineering, and Guangxi Key Laboratory of Calcium Carbonate Resources Comprehensive Utilization, Hezhou University, Hezhou, Guangxi, P. R. China