Effect of different pre-treatments and low-temperature pyrolysis on sunflower straw biochar for N2 adsorption

Sunflower straw was pretreated with steam, KOH, H3PO4 and ZnCl2, respectively(the weight fraction of KOH and H3PO4 is 5% and 40% respectively, and the content of ZnCl2 is 3 mol/L). And Four kinds of sunflower straw charcoal were obtained by pyrolysis at 300℃ for 80 min. Then the adsorption properties of sunflower straw charcoal abtained by the pretreatment of steam, KOH, H3PO4 and ZnCl2 under low temperature (no more than 300℃) pyrolysis environment were analyzed. The results showed that the specific surface area of sunflower biochar after the pretreatment by chemical reagent of KOH, H3PO4 and ZnCl2 is significantly increased than that of the pretreatment with steam, and the adsorption performance is better also. In which, the adsorption performance of sunflower stalk pre-treated by H3PO4 is the best, the specific surface area is 877.56 m2/g, the average pore diameter is 0.52 nm, the maximum adsorption capacity of N2 under 77 K is 353 cm3/g, and the adsorption capacity of Pb2+ at room temperature(25℃) is 109 mg/g. © 2019, Editorial Board of Acta Energiae Solaris Sinica. All right reserved.