Photocatalytically regenerable Cu2O/Cu/biochar adsorbents by facilely synchronous carbonization-activation-functionalization pyrolysis of hemp hurds

Abstract The biochar-supported Cu2O/Cu composite (Cu2O/Cu/BC) was fabricated by direct pyrolysis of hemp hurds pretreated with KOH and CuCl2, in which the synchronous carbonization-activation-functionalization was achieved to produce copper-modified biochars. Cu2O/Cu/BCs were characterized by XRD, Raman, XPS, SEM and N2 adsorption-desorption techniques. The adsorption methyl orange by Cu2O/Cu/BCs showed that the incorporation of Cu2O/Cu has improved the adsorption capacity. The adsorption obeyed the pseudo-second-order kinetic model and Langmuir isotherm. The maximum adsorption capacity reached 379.4 mg∙g-1 at 303.5 K. Furthermore, assisted with the photoactivity of Cu2O/Cu heterojunction the saturated adsorbent can be regenerated under simulated sunlight, and the re-adsorption capacity was still as high as 77.1% of the fresh adsorbent after six cycles. The regeneration efficiency was much better than traditional thermal regeneration and solvent treatment. This work should allow to provide a convenient preparation of functionalized biochars and to develop solar-driven, self-regenerative sorbents for water decontamination with high efficiency.