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Highlights • ACHC with abundant amino, hydroxyl and carboxylate groups was prepared successfully. • ACHC can remove efficiently and rapidly MB and Cu(II) from aqueous solution. • The surface chelation was mainly contribute to Cu(II) adsorption. • π-π interaction, hydrogen bond and electrostatic attraction dominated MB adsorption. Abstract The polyaminocarboxylated modified hydrochar (ACHC) was synthesized to introduce abundant amino, hydroxyl and carboxylate multifunctional groups onto the surface of hydrochar by etherification, amination and carboxylated reaction. The ACHC was systematically characterized and used to evaluate adsorption properties of Cu(II) and methylene blue (MB) by batch sorption tests. The adsorption process toward Cu(II) and MB by ACHC obeyed the pseudo-second-order kinetic model and Langmuir model. Characteristic analysis indicated the surface chelation was mainly contribute to Cu(II) adsorption by large amounts of amino and carboxylate groups while π-π interaction, hydrogen bonding and electrostatic attraction dominated MB adsorption. The maximum adsorption capacities of ACHC were 140.65 and 1238.66 mg·g−1 for Cu(II) and MB at 303 K, respectively. Approximately 97% of the adsorptive uptakes for two pollutants were removed within merely 5 min for kinetic experiment. Competitive adsorption of Cu(II) and MB, and treatment of electroplating wastewater by ACHC were also investigated. [ABSTRACT FROM AUTHOR]

• Co-HTC of PVC and bamboo was employed to prepare high-efficiency adsorbent. • The contents of hydroxyl and carboxyl groups of hydrochar increased during Co-HTC. • Adsorption capacity of MB on hydrochar produced by addition of PVC increased significantly. • Electrostatic and hydrogen-bonding interactions are the main mechanisms. Polyvinyl chloride (PVC) was blended into bamboo powder during co-hydrothermal carbonization (Co-HTC) to understand the effects on the physicochemical properties and adsorbing ability of hydrochar. The properties of hydrochar were characterized by Zeta potential, elemental analyses, BET, FTIR, XPS, Boehm titration and SEM. The addition of PVC into bamboo in Co-HTC decreased the BET area, and pore volume and radius of hydrochar, but increased the contents of surface hydroxyl and carboxyl groups. The adsorption ability of hydrochar produced by addition of PVC at 473 K over methylene blue (MB) increased significantly. The main adsorption mechanism was electrostatic attraction by –N(CH 3) 2 + of MB and carboxylate of hydrochar, and hydrogen-bonding interaction through N atom of phenothiazine in MB and C–OH of hydrochar. Thus, Co-HTC offers a facile, green and economical alternative for conversion of waste into high-value adsorbents. [ABSTRACT FROM AUTHOR]