Efficient removal of noxious methylene dye by low-cost and reusable composite beads based on cellulose acetate/banana pseudo-stem fiber

Abstract Converting agricultural waste into an effectual adsorbent material for removing organic pollutants without creating secondary pollution has received considerable attention. Herein, a green approach was employed to construct eco-friendly composite beads with ease-separation and reusability features for the adsorption of methylene blue (MB) dye. The treated banana pseudo-stem fibers (BFs) were functionalized using iminodiacetic acid (IDA) and impregnated into cellulose acetate beads. The developed IDA-BFs@CA composite beads were analyzed by FTIR, TGA, SEM, XRD, UV-Vis, photoluminescence, BET, XPS, and zeta potential characterization tools. The composite beads demonstrated a porous structure; negatively charged surface (−27.4 mV) and acceptable surface area reached 38.29 m 2 /g with a pore volume of 0.097 cm 3 /g. In addition, the removal (%) was greatly improved and reached a maximal value of 85% using CA:IDA-BFs (1:3) blend ratio compared to 60% using CA:IDA-BFs (1:3) ratio. The isotherms study pointed out that the adsorption of MB dye unveiled a favorable correlation with the Langmuir model ( R 2 = 0.987) with a maximum adsorption capacity of 124.3 mg/g at 25 °C, while adsorption data followed the pseudo-second-order kinetic model. Thermodynamically, the adsorption process was endothermic, random, and spontaneous. The removal mechanism involves both physical and chemical adsorption such as electrostatic interactions, H-bonding, and pore filling. Besides, the reusability study implied that the developed beads reserved admirable adsorption properties with a maximal removal efficiency exceeding 79% after six sequential cycles, emphasizing its potential for removing cationic dye from industrial wastewater bodies. Graphical Abstract