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, pHpzc 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.