Preparation of aligned porous carbon microtubes by a reactant permeation template method and the highly selective adsorption of methylene blue dye from wastewater.

A novel reactant permeation template method was used for the first time to synthesize centimeter-scale aligned porous carbon microtubes, which showed highly efficient selective adsorption and seperation capacity for methylene blue from other dyes. [Display omitted] • Aligned porous carbon microtubes of macroscopic size were prepared for the first time. • A novel reactant permeation template method was used to prepare the carbon microtubes. • The carbon microtubes could adsorb and separate MB selectively from other dyes. • Both the adsorbed MB and the carbon microtubes could be recycled by desorption. • The selective adsorption mechanism of the carbon microtubes was fully researched. Selective adsorption was beneficial to the separation and recovery of valuable dyes and highly efficient resource utilization. Modified aligned porous carbon microtubes (MAPCTs) in centimeter scale were prepared by a novel reactant permeation template method without addition of pore former. In a solution of pH 8, MAPCTs showed excellent adsorption capacity for cationic dye methylene blue (MB), which reached 1875.4 mg/g when the initial concentration of MB increased to 200 mg/L. The adsorption process was fitted by isotherm model and kinetic model. In addition, MAPCTs could selectively separate MB from cationic dye rhodamine B (RhB) or anionic dye methyl orange (MO) mixture solutions, because the reactant permeation template method well controlled the characteristics of the pores. The separation efficiency for MB/RhB and MB/MO solutions was 99.7 %. The adsorbed MB could be efficiently regenerated from the recycled MAPCTs and the adsorption–desorption could be repeated for at least 5 times, keeping the regeneration efficiency 98 %. The selective adsorption and separation process could follow a diffusion limitation and size exclusion mechanism and an electrostatic repulsion mechanism. Since the reactant permeation template method can be easily used for industrial mass production of MAPCTs, this method and MAPCTs have great potential for recycling MB from industrial wastewater. [ABSTRACT FROM AUTHOR]