Preparation of straw biochar and application of constructed wetland in China: A review

China is rich in straw resources, but its utilization value is low. The preparation of biochar from straw will help to improve the utilization level of straw and realize the full utilization of straw. Based on the literature review, it is found that the content of volatile matter is 60-80% in dry straw, and the content of fixed carbon is 13-25%. The content of carbon element in straw is about 40%, which is a good material for biochar production. It was found that the specific surface area, pore volume and pore size of straw biochar could be improved by reducing the heating rate and prolonging the carbonization time. The results show that the simulation effect of pseudo second-order kinetic equation is better than that of pseudo first-order kinetic model. In the future work, the research on biochar gasification pyrolysis, low-temperature carbonization and the purification mechanism of constructed wetland (CW) related to properties of biochar materials needs to be strengthened. The related research points out the direction for the challenges and future research of biochar preparation and biochar CW application. (c) 2020 Elsevier Ltd. All rights reserved.