Mechanistic Study of Phosphoric Acid Activated Magnesium Oxide Nanoparticles for the Removal of Crystal Violet and Methylene Blue from Textile Wastewater

Abstract

The discharge of toxic dyes from textile industries into water bodies poses significant environmental and health hazards. This study explores the green synthesis of magnesium oxide nanoparticles (MgONPs) using Cola acuminata leaf extract, optimized through the Taguchi Design of Experiment to enhance surface area for effective toxic dye removal. The synthesized MgONPs were further surface-activated using phosphoric acid (MgONPs@H3P4) to improve functional moieties for selective removal of crystal violet (CV) and methylene blue (MB) from textile effluent. Comprehensive characterization using FTIR, XRD, HRSEM, and BET analysis confirmed the functional groups, morphological, structural, and surface properties of the nanomaterials. The adsorption performance of MgONPs@H3P4 was evaluated under varying pH, contact time, adsorbent dosage, and temperature conditions, with equilibrium data fitted to isotherm and kinetic models. Results demonstrated that MgONPs@H3P4 exhibited superior adsorption capacities for CV (497.50 mg/g) and MB (484.50 mg/g) at the pH (8), contact time (40 min), adsorbent dosage (25 mg/L), and temperature (50 °C). The experimental data followed pseudo-second-order kinetics and Langmuir isotherm models, indicating monolayer adsorption on the nanoadsorbent surface. Thermodynamic analysis revealed that the adsorption process was spontaneous and endothermic. Reusability studies confirmed the high stability of MgONPs@H3PO4, maintaining over 85 % removal efficiency after ten cycles. Furthermore, MgONPs@H3PO4 showed the adsorption costs of 0.16 and 0.15 US$/g for the removal of a unit weight of CV and MB from textile wastewater which can significantly reduce with ten reusability cycles. The CV and MB adsorption mechanisms indicated electrostatic interaction, hydrogen bonding, cation π-πinteraction, surface complexation and physical adsorption through various internal and surface moieties. This study highlights the potential of bio-inspired, surface-modified MgONPs as an efficient and sustainable adsorbent for textile wastewater remediation.

Department(s)

Chemical and Biochemical Engineering

Keywords and Phrases

Adsorption mechanism; Dye removal; Magnesium oxide nanoparticles; Reusability; Taguchi optimization

International Standard Serial Number (ISSN)

2213-3437

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2025 Elsevier, All rights reserved.

Publication Date

01 Jun 2025

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