Adsorption of Azo Dye Methyl Orange from Aqueous Solutions Using Alkali-Activated Polypyrrole-Based Graphene Oxide

Abstract

The adsorption of methyl orange (MO) from aqueous solutions onto a KOH-activated polypyrrole-based adsorbent (PACK) was investigated using batch and fixed-bed column techniques. The structural, thermal, and morphological properties of the PACK, analyzed by various methods, support its applicability as an adsorbent. An adsorption kinetic study revealed a preferably pseudo-second-order (R2 = 0.9996) and rate-limiting step controlled by both film and intra-particle diffusions. The thermodynamic adsorption tests resulted in negative ΔG°, ΔH°, and ΔS° values, which decreased as the temperature and concentration increased, indicating the spontaneous and exothermic adsorption over 25–45 °C. The adsorption isotherms fit the experimental data in the order of Langmuir ≈ Freundlich > Temkin, with evidence of adsorption operating well via the monolayer physical adsorption process, and maximum monolayer adsorption ranging from 520.8 to 497.5 mg/g. The breakthrough curve of the fixed-bed column experiment was modeled using the Thomas, Yoon–Nelson, and Hill models, resulting in an equilibrium capacity of 57.21 mg/g. A 73% MO recovery was achieved, indicating the possibility of column regeneration. Compared to other adsorbents reported, PACK had comparable or even superior capacity toward MO. For cost-effectiveness, similar nitrogen-containing polymeric wastes could be exploited to obtain such excellent materials for various applications.

Effective Removal of Malachite Green from Aqueous Solutions Using Magnetic Nanocomposite: Synthesis, Characterization, and Equilibrium Study

“…On the basis of R 2 values, the adsorption kinetics fit PSO (R 2 = 0:998) better than the PFO (R 2 = 0:991), suggesting that the adsorption of MG onto Fe 3 O 4 @AJPL occurred by the chemisorption mechanism. Moreover, the q e , calculated according to the PSO kinetic model (q e , cal = 18:36 mg/g), was closer to the experimental 9)) [62]:…”

Adsorptive Performance of Polypyrrole-Based KOH-Activated Carbon for the Cationic Dye Crystal Violet: Kinetic and Equilibrium Studies

“…Characterization. The essential features of the adsorbent PACK, including its structural and surface properties as well as its efficacies as an adsorbent of gasses, heavy metal ions, and anionic dyes represented by carbon dioxide (CO 2 ), lead ions (Pb 2+ ), and methyl orange (MO), respectively, have been reported by Alghamdi et al [15][16][17] and Sevilla et al [18] (Table 1). Furthermore, to obtain insight into the surface charge, the pH at which the net surface charge is zero (pH PZC ) was estimated and found to be 6.35 (Figure 2).…”

“…In many cases, modification of such materials has increased their adsorption efficiencies. Conversely, the synthetic adsorbents, including activated carbon, exhibit better performances in the removal of water pollutants ( [16,43]). However, the source of the carbonaceous materials, processing, and activation conditions are important factors in the final properties of the carbon.…”

“…Adsorbent. PACK was prepared as described in the literature [15][16][17][18]. Briefly, HCl-doped polypyrrole (PPy) was prepared using an equimolar quantity (0.08 mol) of the monomer (Py) and the initiator (APS) in cold HCl (1 L, 0.1 M).…”

Conversion of conducting polypyrrole nanostructures to nitrogen-containing carbons and its impact on the adsorption of organic dye

“…For example, the adsorption capacity of alkali-activated carbonized polypyrrole for methyl orange was reported to exceed 500 mg g −1 . 32 The present study merges two research strategies outlined above, /1) the preparation of polypyrrole with controlled nanostructure and (2) their gradual conversion to nitrogencontaining carbonaceous materials followed by their testing in the adsorption of organic dye.…”