A green, rapid, scalable and versatile hydrothermal strategy to fabricate monodisperse carbon spheres with tunable micrometer size and hierarchical porosity.

• The bulk production of hydrothermal carbon microspheres (1.1–7.1 μm) was achieved. • This method is simple, rapid, high-yield and applicable for various carbohydrates. • The hierarchical porosity was formed by H 2 O 2 oxidation and air-assisted calcination. • Porous carbon spheres were covalently quaternized with hyperbranched polymers. • Modified porous carbon spheres show good separation for inorganic anions and sugars. Monodisperse micron-grade carbon spheres (MCSs) (1.1–7.1 μm) were prepared via the hydrothermal carbonization of maltose with the addition of polyacrylic and inorganic acid. The synthesis could be accomplished in 3 h and still take effect at a large maltose concentration (∼800 g/L) or in tenfold enlarged experiments. This strategy was also applicable to form MCSs with good monodispersity for various carbohydrates including glucose, sucrose, soluble starch, xylan, glucan and barley starch. The simple H 2 O 2 oxidation and calcination under static air atmosphere could introduce good surface meso- and macroporosity (average pore size of 4.2 nm, 79% of total pore volume) onto MCSs. The covalent grafting of porous MCSs with hyperbranched quaternized polymers was implemented in aqueous solution, via amidation with polyvinylamine and following amine-epoxy addition reaction with 1,4-butanediol diglycidyl ether. As ion chromatographic stationary phases, the modified porous MCSs rapidly accomplished the baseline separation of typical inorganic anions and carbohydrates with high efficiency and satisfactory stability. [ABSTRACT FROM AUTHOR]