Activated biochar loaded CuAl-layered double hydroxide composite for the removal of aniline aerofloat in wastewater: Synthesis, characterization, and adsorption mechanism

It is challenging to completely biodegrade and oxidise aniline aerofloat wastewater. Rapid and efficient treatment of aniline aerofloat wastewater remains a challenge. Herein, inspired by the structural characteristics of aniline aerofloat and the fact that it can collect chalcopyrite well, a CuAl-layered double hydroxide composite-activated biochar adsorbent was studied. It was subsequently applied to aniline aerofloat wastewater treatment. In this study, a CuAl-layered double hydroxide/K₂CO₃activated biochar composite (CKBC) was synthesised by hydrothermal method with K₂CO₃activated biochar (KBC) as a carrier. KBC was prepared from rice straw biochar activated by K₂CO₃. The materials were characterised using a scanning electron microscope (SEM), X-ray diffraction (XRD), nitrogen adsorption analysis, and Fourier transform infrared spectroscopy (FTIR) analysis. The effects of pH, initial aniline aerofloat concentration, and adsorption time were investigated. The results demonstrated that under the conditions of pH 6, 80 mg/L concentration, and adsorption for 2 h, 96.6 % aniline aerofloat could be removed. The KBC and CKBC adsorption kinetics demonstrated a higher fitting degree with the Elovich equation, KBC adsorption isotherm data followed the Freundlich model, and CKBC could be better described by the Temkin model. X-ray photoelectron spectroscopy (XPS), FTIR, and SEM were used to explore the adsorption mechanism. The results demonstrate that the interaction between CKBC and aniline aerofloat predominantly includes pore filling, hydrogen bonding, π-πinteractions, complexation, and electrostatic attraction. Based on the above merits, designing comprehensive composites offers new insights into adsorbents and reveals their applications.