Turning Prosopis juliflora invasive biomass into a sustainable adsorbent: Mechanistic and reusability studies for methylene blue removal

This research examined the effectiveness of invasive Prosopis juliflora biomass as a viable adsorbent for methylene blue sequestration from liquid. It focused on characterizing the inherent nature of the adsorbent material, assessing its effectiveness in sequestering the adsorbate from liquids, and examining the effects of pH (1–11), contact time (0–240 min), dye concentration (5–150 mg/L), sorbent mass (0.1–2 g), and temperature (20–40 °C) on batch sorption performance. The results revealed over 95% removal and a 28.65 mg/g maximum sorption capacity per unit mass when individual factors were optimized. The adsorbent structure was scanned using scanning electron microscopy, its moieties were determined via Fourier transform infrared spectroscopy, and its area was quantified through the Brunauer‒Emmett–Teller method. Characterization confirmed that Prosopis juliflora seed powder is suitable for methylene blue sequestration. The pseudo-second-order, Elovich, Lagergren, and Weber‒Morris models were used to prioritize the most appropriate adsorption kinetics. The sorption data were most accurately fitted by pseudo-second-order kinetics, with an R2 of 0.99. Among the isotherm models tested, including the Dubinin–Radushkevich, Temkin, Langmuir, and Freundlich isotherms, the Freundlich model had the best fit, with an R2 of 0.99. Desorption studies revealed a preliminary recovery rate of 80.18%. In conclusion, Prosopis juliflora biomass has high potential as a proficient adsorbent for methylene blue removal from aqueous media.