Evaluation of The Selectivity, Performance, and Regeneration Capability of Ni/Cr-Gambier Leaf Extract Composites for Anionic Dyes Removal

This study investigated the potential of Ni/Cr layered double hydroxide (LDH) and its composite with gambier leaf extract (GLE) as an adsorbent for anionic dye removal from the solution. Ni/Cr LDH material was synthesized via the co-precipitation method and combined with GLE to form Ni/Cr-GLE composite using aquatic solvent under nitrogen conditions. Characterization revealed significant structural changes in Ni/Cr-GLE, as seen in XRD, FT-IR, and BET analysis, which showed the integration of GLE and an increase in surface area. FT-IR analysis confirmed the presence of catechin compounds on the GLE, while BET showed a surface area of 0.65 m²/g on Ni/Cr-GLE, higher than 0.42 m²/g on Ni/Cr LDH. Selectivity studies on anionic dyes showed a high affinity of Ni/Cr-GLE towards methyl orange (MO), with a maximum adsorption capacity (Qmax) of 214.285 mg/g, much higher than that of 36.363 mg/g on Ni/Cr LDH. The isotherms of Ni/Cr-GLE conformed to the Freundlich model, while the adsorption kinetics followed the PSO model. In addition, the adsorption process occurs spontaneously, absorbing heat (endothermic). Regeneration results showed the ability of Ni/Cr-GLE to maintain its adsorption capacity after several reuse cycles, indicating its structural stability.