Adsorptive Removal of Toxic Dye Using Novel Lima Bean‐Derived Activated Carbon@Al ₂ O ₃ Composite: Kinetic, Isothermal, Phytotoxicity, Antimicrobial Study

ABSTRACT Malachite green (MG) is particularly concerning due to its environmental persistence and acute toxicity to a wide range of aquatic and terrestrial organisms. For the refinement of water, we introduce a novel adsorbent, activated carbon derived from waste biomass of Lima bean pods synthesized and combined with Al 2 O 3 material to form the composite. This novel adsorbent is utilized to remove hazardous MG dye from aqueous solutions in batch mode experiments. The results indicated that the composite achieved an impressive removal efficiency of 99.43%. The composite's maximum adsorption capacity could reach 1250 mg g −1 at a pH of 8, with an adsorbent dosage of merely 0.03 g L −1 . The optimal contact time for achieving maximum dye removal was determined to be 135 min at 298 K. Characterization of the synthesized composite was conducted using XRD, FT‐IR, RAMAN, SEM, EDS, and BET techniques. The adsorption process conformed to pseudo‐second‐order kinetics and the Freundlich isotherm, indicating physisorption. The thermodynamic analysis demonstrated that the adsorption process was spontaneous and exothermic. Additionally, the material exhibited good recyclability, and the phytotoxicity study reveals successful removal of the dye from the solutions. Adsorbent has shown antimicrobial properties toward Escherichia coli ( E. coli ). It may be concluded that, current adsorbent is best versatile adsorbent.