Preparation of porous biomass-derived hydrothermal carbon modified with terminal amino hyperbranched polymer for prominent Cr(VI) removal from water.

Herein, a series of functionalized hydrochars with high density of nitrogen-containing functional groups were engineered by co-processing of terminal amino hyperbranched polymer and walnut shell biomass in the hydrothermal carbonization media. Hydrothermal Carbonization with optimized key parameters was implemented to determine the impact of added polymer to the biomass on the properties of the obtained hydrochars. Consequently, the optimum hydrochar which was achieved with the values of 250 °C, 60 min, and 50% (w/w) for temperature, time, and polymer/biomass weight ratio, demonstrated a highly improved surface area of 544 m2.g-1 and the highest adsorption capacity for Cr(VI) removal which was obtained from Freundlich isotherm model and described by the pseudo-second-order kinetic model to be 363.22 mg.g-1 (at pH = 2.0). This work suggests that the co-hydrothermal carbonization promotes the uniform incorporation of polymers into the hydrochar matrix and provides adsorbents for the effective removal of Cr(VI) from water.