Effects of cation types in persulfate on physicochemical and adsorptive properties of biochar prepared from persulfate-pretreated bamboo.

[Display omitted] • Two biochars were prepared from APS/KPS-pretreated bamboo. • Cation types in persulfate impact physicochemical properties of biochar. • The KPS-pretreated bamboo-derived biochar has a higher adsorptive capacity for MB. • The discrepancy in adsorption capacity of two biochar for MB was analyzed. • Electrostatic action is the main adsorption mechanism for MB onto biochars. The adsorption behaviors of biochar are largely impacted by biomass feedstock. In this study, two biochars were prepared from torrefaction of ammonium persulfate- and potassium persulfate-pretreated bamboo and then activated by cold alkali, which are named as ASBC and KSBC, respectively. The two biochars were characterized by different instruments, and their adsorption properties over cationic methylene blue (MB) were compared. The type of persulfates little affected the specific surface areas, but significantly impacted O (29.54 % vs. 35.113 %) and N (12.13 % vs. 3.74 %) contents, functional groups, and zeta potentials of biochars. MB adsorption onto ASBC/KSBC is a single-layer chemical endothermic process and ASBC/KSBC exhibit high adsorption capacity over MB (475/881 mg·g−1) at 303 K. Obviously, the sorption capacity of MB onto KSBC much surpasses that of MB onto ASBC. These results indicate biomass pre-treatment is a cheap and convenient method to prepare biochars with unique physicochemical and adsorptive properties. [ABSTRACT FROM AUTHOR]