Removal of Congo red dye from industrial effluents using metal oxide-clay nanocomposites: Insight into adsorption and precipitation mechanisms

• DOI: 10.1016/j.wri.2024.100253
• Publication Date: 2024-03-15T04:31:34Z
• Authors: T.E. Rasilingwani; J.R. Gumbo; V. Masindi; S. Foteinis
• Keywords: Bentonite; Congo red; Langmuir adsorption model

The efficacy of magnesium oxide (MgO)-bentonite clay nanocomposite (MgO nanoparticles embedded in powdered bentonite clay) for water and wastewater treatment applications is examined herein. Congo red (CR), a widely used azo dye, was as the model contaminant. For CR concentrations ≤120 mg/L, optimum dosage ≤1 g/L, achieving removal ≥99% contact times (mixing durations) ≤10 min, whereas temperature pH had no significant effect on process. dye followed pseudo-second-order than first order model. Furthermore, adsorption isotherms Langmuir isotherm rather Freundlich (R2 ≥ 0.99), hence confirming monolayer homogenous adsorption. surface morphological physicochemical characteristics were also identified, results suggest that governed by electrostatic attraction between protonated hydroxyl groups (i.e., -OH2+), surface, negatively charged –SO3-groups dye. When real printing ink wastewater, practically removed (⁓100%), dyeing (PDW), more challenging effluent contains salts other contaminants, ≥80%. Overall, produced MgO-bentonite hold great promise sustainable removal, typical contaminant released many industries including printing, tannery textile, paper, plastic, paint coatings.