methylene blue removal in airlift bioreactor packed with coelastrella biosorbent

Water contamination by methylene blue (mb) is a significant environmental challenge that requires cost-effective purification strategies. the green algae coelastrella was used as an adsorbent inside the airlift bioreactor as an effective and inexpensive material. experiments were conducted over a range of conditions, including initial mb concentration (3-30 mg/l), contact time (0-60 min), air flow rate (200-300 ml/min), algae dosage (0.1-2 g/l), and temperature (20-40 ˚c). diverse characterization techniques were employed to comprehensively understand the process and its outcomes. these techniques include energy dispersive spectroscopy (eds), fourier transform-infrared (ft-ir) spectroscopy, uv-visible (uv-vis) spectrophotometry, and scanning electron microscopy (sem). adsorption isotherms were analyzed in this study, with a focus on the langmuir, freundlich, and temkin models. the langmuir model had the highest (r² = 0.9998), indicating monolayer adsorption with a maximum adsorption capacity of 30 mg/g. additionally, kinetic studies found the pseudo-second-order model to be the most accurate (r² = 0.9990). under optimal conditions, the process achieved a high removal efficiency of 98.9%. finally, mass transfer adsorption models were examined using three models. when these models were compared, the liquid film diffusion model had the highest value (r² = 0.9736). these results suggest that algae biomass is an effective, green adsorbent for mb removal, presenting a viable alternative to conventional treatments.