Studies on the Removal of Congo Red Dye by an Adsorbent Based on Fly-Ash@Fe3O4 Mixture

Abstract

The effectiveness of a Fe3O4-loaded fly ash composite for the adsorption of Congo red dye was assessed in this work. The structure and properties of the magnetic adsorbent were established by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), X-ray diffractometer (XRD), vibrating sample magnetometer (VSM), and dynamic light scattering (DLS). The magnetic results showed a saturation magnetization value of 6.51 emu/g and superparamagnetic behavior. The main parameters that influence the removal of Congo red dye adsorbent such as dose, initial concentration, and contact time were examined. The Freundlich adsorption isotherm and pseudo-second-order kinetic model provided the best fit for the experimental findings. The Congo red dye’s maximum adsorption capacity of 154 mg/g was reported in the concentration range of 10–100 mg/L, using the proposed magnetic adsorbent. The results of the recyclability investigation demonstrated that the circular economy idea is valid. The adsorbent that was synthesized was also further characterized by XRD and FTIR techniques after Congo red dye adsorption.

Adsorption and Removal of Industrial Dyes by Water-Stabilized Aluminum-Based Metal–Organic Frameworks

“…As seen from the ζ-potential (Figure c), CAU-23 was positively charged, and the amount of adsorbed CR did not decrease significantly despite the H + ions surrounding the CR molecule competing with the material for adsorption sites, indicating that the material has a higher affinity for −SO 3 groups than H + . Once the pH increases from 8 to 12, the adsorption capacity of CAU-23 decreases dramatically, solely due to the fact that in the weak or basic region, CAU-23 is negatively charged and repels with negatively charged CR . According to the findings shown in Figure c, as the pH of the dye solution increased, dye elimination decreased, while MOF adsorbents exhibited a high degree of adsorption in a neutral medium.…”

“…40 Once the pH increases from 8 to 12, the adsorption capacity of CAU-23 decreases dramatically, solely due to the fact that in the weak or basic region, CAU-23 is negatively charged and repels with negatively charged CR. 41 According to the findings shown in Figure 2c, as the pH of the dye solution increased, dye elimination decreased, while MOF adsorbents exhibited a high degree of adsorption in a neutral medium. Theoretically, when the electrostatic attraction between the adsorbent surface and the adsorbent ions is attractive, the increase in ionic strength will result in an increased removal rate, as seen in Figure 2d, from 96.15 to 99.91% with the addition of 0.1 M Na + .…”

Fabrication and Characterization of Functional Biobased Membranes from Postconsumer Cotton Fabrics and Palm Waste for the Removal of Dyes

“…The volume of the dyes used in the dead-end stirred cell was 300 mL for all separation experiments. In order to check the membrane efficiency, the selected concentration (10 mg L −1 ) of both dyes was higher than the range present in real discharged effluent from pulp and paper industries [ 49 , 50 ]. The functional membranes prepared from EFB, CF, and WFP were called M 1 , M 2, and M 3 , respectively.…”

Hyperbranched-Polyethylenimine-Functionalized Coal Fly Ash as an Adsorbent for the Removal of Hexavalent Chromium and Reuse as a Dye Photocatalyst

“…The Fe 3 O 4 -loaded fly ash composite was found to possess better magnetic characteristics, which resulted in improved adsorption capacity when compared with that of raw CFA and NaOH-treated CFA. 21 Carbon-based compounds such as amine, polydopamine, and β-cyclodextrin were used to modify CFA to prepare polydopamine-βcyclodextrin−CFA composite for the remediation of uranium from water. The maximum adsorption capacity of 536.7 mg/g was obtained with the removal efficiency of 95.6% at pH 5.0 through complexation, hydrogen bonding, and electrostatic interaction.…”

“…The effectiveness of Fe 3 O 4 -loaded fly ash composite for the remediation of Congo red dye from water was investigated. The Fe 3 O 4 -loaded fly ash composite was found to possess better magnetic characteristics, which resulted in improved adsorption capacity when compared with that of raw CFA and NaOH-treated CFA . Carbon-based compounds such as amine, polydopamine, and β-cyclodextrin were used to modify CFA to prepare polydopamine-β-cyclodextrin–CFA composite for the remediation of uranium from water.…”