▎ 摘　　要

The current research aimed to develop an eco-friendly three-dimensional (3D) graphene oxide/high molecular weight chitosan (GO/HCS) composite for the removal of Reactive Black 5 (RB5) dye. The adsorption performance of the 3D GO/HCS adsorbent was elucidated by varying the adsorbent dosage (1-50 mg), agitation speed (50-250 rpm), initial RB5 concentration (100-600 mg/L), pH (2-11), temperature (30-70 degrees C) and contact time (1-90 min). The equilibrium behaviour of the 3D GO/HCS adsorbent was best described by the Langmuir isotherm (SNE: 2.27 to 3.92), demonstrating a maximum adsorption capacity of 638.93 mg/g. The kinetic study showed a relatively fast RB5 dye adsorption by the as-synthesised 3D GO/HCS composite. The dye uptake by the composite was thermodynamically spontaneous (Delta G: -39.15 to -17.90 kJ/mol) and endothermic (Delta H: 5.60 to 31.64 kJ/mol). The adsorption mechanisms were assayed by pH test, Fourier transform infrared and X-ray photoelectron spectroscopy. The results substantiated that electrostatic attraction and pi - pi stacking were the prevailing uptake mechanisms. The 3D GO/HCS composite exhibited high structural stability and RB5 dye removal efficiencies within pH of 2-10. Furthermore, the exhausted 3D GO/HCS adsorbent was easily recovered from the liquid phase. The adsorbent was successfully applied in 5 cycles of adsorption-regeneration, preserving 90% of its adsorption capacity. The excellent adsorption and regeneration efficiencies inferred that the 3D GO/HCS macrostructure was highly efficient and recyclable for aqueous RB5 dye sequestration. (C) 2020 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.