Cr(VI) removal from water using cobalt-coated bamboo charcoal prepared with microwave heating

Bamboo charcoal-based, cobalt-coated adsorbent (Co-MBC) was developed by Co(NO3)2 and HNO3 simultaneous impregnating treatment assisted with microwave irradiation. The virgin and modified bamboo charcoals were characterized by means of XRD, SEM-EDS, FT-IR, BET and point of zero charge (pHpzc) measurement. The results showed that Co-MBC exhibited higher surface area of 263 m2/g and pore volume of 0.27 cm3/g than those of the virgin bamboo charcoal (MBC). As an adsorbent, Co-MBC showed an excellent adsorption capability for Cr(VI), the adsorption process followed the Langmuir isotherm model well, the adsorption kinetic followed pseudo-second order model. The adsorption of Cr(VI) onto Co-MBC was spontaneous and exothermic in nature, and the addition of Co2+ was advantageous to the spontaneous process, and the ion exchange mechanism played an significant role.The regeneration shows that the Co-MBC has good reuse performance and the hexavalent chromium was recycled.

► A novel process for the preparation of cobalt-containing bamboo charcoal (Co-MBC) is developed.
► The presence of cobalt significantly affects the surface area and pore structure of the Co-MBC.
► Co-MBC is a useful adsorbent for Cr(VI) and the spent Co-MBC can be readily regenerated for reuse by dilute NaOH solution.