Study on Physicochemical Properties and Surface Properties of Biochar from Different Materials

[Objectives]This study was conducted to explore the differences in physicochemical properties and surface properties of biochar from different sources.[Methods]Four kinds of materials including rice husk and corn straw were prepared at 450℃by the limited-oxygen program temperature control method into biochar,and the differences in physicochemical properties and surface properties of the biochar from different sources were studied.[Results]All four kinds of biochar were alkaline(pH=8.7-10.0).Corn straw biochar had the highest organic carbon content(653.6 g/kg),while rice husk biochar had the lowest organic carbon content(486.1 g/kg).Corn straw biochar had the highest nitrogen content(2.7%),while rice husk biochar had the lowest nitrogen content(0.75%).Corn straw biochar had the highest total phosphorus content(5.64 g/kg),while rice husk biochar had the lowest total phosphorus content(1.1 g/kg).Rice straw biochar had the highest total potassium content(53.1 g/kg),while rice husk biochar had the lowest total potassium content(10.6 g/kg).The four types of biochar were all porous,but their pore structure sizes and shapes were different to certain degrees.The order of the specific surface areas of the four types of biochar was rice stalk biochar>corn stalk biochar>wheat stalk biochar>rice husk biochar;the order of the pore volumes was rice stalk biochar>corn stalk biochar>wheat stalk biochar Charcoal>rice husk biochar;and the pore sizes ranked as wheat stalk biochar>corn stalk biochar>rice husk biochar>rice stalk biochar.The biochar from different sources ranked according to the comprehensive evaluation of all indicators as corn straw biochar>wheat straw biochar>rice straw biochar>rice husk biochar.[Conclusions]This study provides reference data for the preparation process of biochar from industrial and agricultural wastes and its application and promotion.