Sustainable Synthesis, Characterization and Adsorptive Application of Rice Husk-derived Magnesium Oxide Nanocomposites for Congo Red Removal from Aqueous Solutions
J. Environ. Nanotechnol., Volume 15, No 3 (September 2026) pp. 405-420
Abstract
Water pollution continues to be a major global issue in the twenty-first century, requiring sophisticated and sustainable technology to safeguard human health, improve water quality, and conserve aquatic ecosystems. This work examines eco-friendly manufacture of magnesium oxide nanoparticles using rice husk as sustainable biomass source and assesses their efficacy in adsorbing Congo Red from aqueous solutions. Four MgO–rice husk nanocomposites, labeled RH–MgO-1, RH–MgO-2, RHB–MgO-1, and RHB–MgO-2, were synthesized and characterized through Fourier transform infrared spectroscopy, X-ray diffraction and scanning electron microscopy, to analyze their morphological, structural, and crystalline properties. Batch adsorption tests indicated optimal pH values of 8.5 for RH–MgO-1 (37.8 mg/g), 9.0 for RH–MgO-2 (39.0 mg/g), and 9.5 for both RHB–MgO-1 (43.6 mg/g) and RHB–MgO-2 (45.1 mg/g). The adsorption capabilities were determined using an adsorbent dosage of 0.05 g and contact duration of 45 minutes. The maximum adsorption capacities of 44.7, 58.2, 73.8, and 79.2 mg/g were attained for RH–MgO-1, RH–MgO-2, RHB–MgO-1, and RHB–MgO-2, respectively. Pseudo-first-order model yielded optimal fit for experimental data, whereas Langmuir model effectively characterized adsorption equilibrium, suggesting primarily monolayer adsorption. Thermodynamic evaluation verified that the process was spontaneous and exothermic. The impact of prevalent textile wastewater electrolytes (AlCl3·6H2O and NaCl, CaCl2·2H2O) at concentrations from 0.05 to 0.50 M, alongside heavy metal ions (lead and chromium) at 40 to 200 ppm, on the adsorption efficacy of Congo Red dye was systematically examined. Findings indicate that the synthesized MgO–rice husk nanocomposites are economical, eco-friendly, and highly effective adsorbents, possessing considerable potential for sustainable remediation of dye-contaminated wastewater.
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Reference
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