Abstract: Six different types of agricultural and forestry wastes, such as wheat straw, peanut shell, coconut shell, etc., were used to prepare biochar. The adsorption performance of different biochar on petroleum in water were studied. The effects of biochar type and dosage, oil type and concentration, adsorption time and other factors on the adsorption of oil in water by biochar were systematically investigated. The results showed that the biochar prepared from different raw materials had good adsorption capacity for oil in water, and the adsorption capacity was 142.70-493.86 mg/g. Among them, the biochar prepared from wheat straw with many carbon functional groups had the largest adsorption capacity for petroleum, and its total pore volume was 0.155 cm³/g, which was significantly larger than other biochars. The optimal dosage of wheat straw biochar for adsorption of petroleum in water was 0.25 g/L, and the adsorption equilibrium time was 60 min. The adsorption process conformed to the quasi-second-order kinetic equation and Langmuir isotherm adsorption model, that was, closer to the monolayer adsorption. The oil adsorption capacityof biochar was affected by many factors, and the oil concentration had the greatest impact on the adsorption capacity of biochar.

Key words: petroleum, agricultural and forestry wastes, biochar, grey correlation degree, influence factor