Hydrogels have emerged as promising water and wastewater treatment materials due to their unique properties, such as hydrophilicity, swellability, and modifiability. Herein, alginate hydrogel (ALG) containing biomass derived from Lantana camara L. stem (LSB) was proposed as a novel bio-composite for the adsorptive removal of methylene blue (MB) from aqueous solutions. The optimized condition to achieved the maximum biosorption capacity and removal efficiency of MB using ALG/LSB bio-composite was obtained at the pH value of 9, polymer concentration of 1.25% w/v, a bio-composite dosage of 0.29 g.L-1 (90 mg.L-1 of ALG containing 0.2 g.L-1 of LSB), initial MB concentration of 50 mg.L-1, environmental temperature of 318 K, and at 50 min. The findings were closer to the Langmuir model (R2=0.9997), which characterizes monomolecular adsorption on homogeneous surfaces. The maximum adsorption capacity of the analyte using the synthesized bio-composite was 178.57 mg.g-1. The adsorption rate was acceptably characterized by the pseudo-second-order kinetic model (R2 = 0.99 and qe = 185.15 mg.g-1). The precision of the Intra-particle diffusion mechanism was evident (R2 = 0.978). The thermodynamic analysis (ΔG° = -11.286 kJ.mol-1, ΔH° = +17793.6 J. mol-1, and ΔS° = +91.445 J. mol-1.K-1 at 318 K) indicated that analyte bio-sorption was both an endothermic and spontaneous process. The ALG/LSB bio-composite was introduced as a novel, cost-effective, efficient, and biocompatible bio-polymeric adsorbent for the removal of cationic dye from aqueous environments.
