Extended evaluation of activated carbon–embedded glucomannan membranes for the adsorption of structurally and charge-distinct dyes

Konjac glucomannan (KGM)/activated carbon (AC) composite membranes were previously shown to retain the intrinsic adsorption capability of AC when removing methylene blue. However, the applicability of this composite system to structurally and electrostatically distinct dyes, and its robustness to variations in KGM source have not been fully evaluated. This study extends the earlier work by examining the adsorption of methyl violet B (MV), a bulkier cationic dye, and methyl orange (MO), an anionic dye, using KGM from a different supplier. Stable KGM/AC membranes were fabricated and showed no leakage of AC during experiments. Both MV and MO exhibited Type-I Langmuir adsorption behavior, and the maximum adsorption capacity increased linearly with the AC mass fraction ( MF AC ), demonstrating that AC embedded in the membrane remained accessible. The Langmuir equilibrium constant showed no systematic dependence on MF AC , indicating that the neutral KGM matrix did not alter the affinity of AC for the dyes. The membrane prepared with a different KGM lot performed comparably to that in the previous study, confirming reproducibility. These findings demonstrate that the KGM/AC membrane maintains AC functionality across dyes with molecular properties and is robust with respect to variation in polymer source.