Protonated-amino-functionalized bamboo hydrochar for efficient removal of hexavalent chromium and methyl orange

Hydrochar has great potential for wastewater treatment and the functional modification can significantly improve the ability of hydrochar to remove pollutants. Herein, a novel protonated amino-modified bamboo hydrochar (PAHC) was synthesized by the reaction of bamboo hydrochar first with acryloyl chloride, then with amine and finally with hydrochloric acid, and employed to adsorb methyl orange (MO) and Cr(VI). The PAHC was observed by BET, SEM-EDX, FTIR, elemental analysis, and zeta potential to monitor its textural properties before and after adsorption. The amino groups were effectively grafted onto the hydrochar by the Aza-Michael addition reaction through characterization. Adsorption results showed the PAHC possessed high MO/Cr(VI) adsorption amounts (515.35/523.57 ​mg ​g−1 ​at 298 ​K) because the introduction of protonated amine was pivotal in eliminating anionic pollutants by electrostatic interaction. The Langmuir/Freundlich model can well describe MO/Cr(VI) adsorption, which proves the removal process belongs to MO monolayer/Cr(VI) multilayer adsorption. The PAHC also exhibited a good regeneration performance. These results indicate the PAHC is a green and efficient adsorbent with potential application in wastewater treatment.