Nature’s allies: Unleashing the potential of oxalic acid-modified Saccharum spontaneum  (kashful stalks) for methylene blue removal from water and wastewater

In this research, we present a sustainable approach for the decontamination of methylene blue from water and wastewater, employing oxalic acid-modified Saccharum spontaneum (Kashful stalks) as an eco-friendly adsorbent. The material was strategically modified to improve its effectiveness and adsorption capabilities. The improved material was comprehensively characterized using field emission scanning electron microscopy, Fourier transform infrared spectroscopy, and pH at isoelectric point (pH ZPC ). A detailed study was conducted to assess the material optimization under varying states, like contact time, concentration, pH, and temperature. The Freundlich isotherm model demonstrated the best fit for the interaction, with an R 2 > 0.99. The kinetics of interaction is best given by pseudo-second-order kinetic indicating chemisorptions. The maximum adsorbability recorded was 54.55 mg/g, indicating the exceptional adsorption capability of the modified material. The material is also efficient in the presence of various ions and real water situations. The thermodynamic investigation demonstrates that the adsorption process is endothermic, viable, and spontaneous, enhancing the viability of the material for large-scale decontamination purposes. The dye-loaded material demonstrated successful regeneration in an alcoholic medium, making it suitable for multiple adsorption–desorption cycles without compromising its efficiency. Graphical abstract