Biosorption of methylene blue from industrial wastewater using silicon dioxide nanoparticles and Cladophora glomerata

Methylene Blue is a common pollutant in industrial wastewater, posing environmental risks, impacting aquatic ecosystems, and degrading the aesthetic quality of water. Biosorption has emerged as an effective alternative for wastewater treatment, utilizing various absorbents, including algae, for the removal of dyes. This study investigates the biosorption efficiency of Methylene Blue using Cladophora glomerata macroalgae and silicon dioxide nanoparticles, which were characterized using SEM and FTIR. Key parameters, including adsorbent dosage, pH, and contact time, were evaluated to optimize the removal process. Under optimal conditions (temperature: 20 ± 2 °C, stirring speed: 300 rpm, contact time: 60 min, pH: 5, initial dye concentration: 20 mg/L, and adsorbent dose: 1.3 g/L), silicon dioxide nanoparticles demonstrated nearly 100 % dye removal. Cladophora glomerata achieved 95.55 % removal within 50 min at a dosage of 1.0 g/L. A hybrid approach combining both adsorbents reached similar removal efficiency in 50 min at a lower dose of 0.6 g/L. Kinetic analysis revealed that the biosorption process followed the pseudo-second-order non-linear model, exhibiting high correlation coefficients (average R² = 0.996, 0.997, and 0.999). The biosorption data were well described by the Elovich kinetic model (R² > 0.9) and fitted both the Langmuir and the Freundlich isotherms, indicating a good fit of the experimental data, confirming monolayer adsorption on heterogeneous surfaces. These findings suggest that Cladophora glomerata, a macroalga, and silicon dioxide nanoparticles are efficient, cost-effective, and environmentally friendly adsorbents for removing Methylene Blue from industrial wastewater.