Preparation of porous carbon-based material from corn straw via mixed alkali and its application for removal of dye

A porous carbon material (PCCS) derived from an agricultural waste (corn straw) was prepared by simple methods including carbonization and chemical activation. It is the first time that the mixed alkali consisted of KOH and NaOH have been used for producing PCCS, and the results indicate that the mixed alkali could be better activator than pure KOH or NaOH. When the ratio of KOH and NaOH was 1 : 1, the PCCS exhibited the highest surface area and best dye adsorption performance. The Brunauer-Emmett-Teller (BET) surface area and the Langmuir surface area achieved 1993 and 3467 m(2) g(-1), respectively. The maximum adsorption capacity of rhodamine B (RhB) over PCCS reached 1578 mg g(-1) at pH value of 7. The pseudo-second-order kinetic model and the Freundlich isotherm model were well fitted with the adsorption data of RhB onto PCCS. Moreover, Fe3O4 magnetic particles were introduced to the surface of PCCS. The composite PCCS@Fe3O4 could be rapidly separated from the aqueous solutions or used as a heterogeneous fenton-like catalyst. It could be expected the strategy of partially replacing KOH with other activators for less pollution and more safety could be applied for the preparation of more porous carbon materials with excellent performances in the future.