Contemporaneous Adsorption Analysis for Removal of Dyes from Multi-dye System

In this research, simultaneous adsorption of rhodamine B (RB) and methyl orange (MO) from mono-dye system (RB/MO) and multi-dye system (RB + MO) was analyzed for antagonistic/synergistic effect. Adsorbent characterization was performed using SEM, EDX, porosimetry, TGA, pH_pzc and XRD analysis. Meanwhile, influence of operating conditions viz. contact time (0–3 h), pH (2–12), dye concentration (1–100 mg/L) and adsorbent dose (0.1–4 g/L) on dyes adsorption from mono-component system was evaluated. Subsequently, rate constants for dyes removal were determined using several kinetic models i.e., pseudo-first-order, intra-particle diffusion, pseudo-second-order, Elovich and liquid-film diffusion models. On the other hand, Langmuir, Freundlich, Elovich, Dubinin-Radushkevich and Temkin isotherm models adopted to explicate maximum adsorption ability and adsorption process mechanism. From results, it was noted that pseudo-second-order (K₂: RB = 1.088 min⁻¹; MO = 0.03 min⁻¹) and Langmuir model best suited experimental data for both RB and MO dye removal. The maximum adsorption ability (mg/g) was found to be 77.52 and 47.84 for RB and MO, respectively at 60 min with dose 2 g/L at neutral pH. In contrast, maximum adsorption ability (mg/g) was found to be 71.9 and 81.3 for RB and MO, respectively from multi-component system. Furthermore, Langmuir competitive model facilitated in analysis of synergistic (cooperative) or antagonistic (competitive) effect for removing dyes from a multi-dye system (RB + MO) and synergistic effect was observed.