Soft phosphorylation of cellulose and starch for effective remediation of methylene blue dye and heavy metal-contaminated water

A soft strategy for the phosphorylation of cellulose and starch has been developed to produce functionalized bioabsorbents (P-Cellulose / P-Starch) for the decontamination of polluted water. The proposed synthesis pathway utilizes only phosphorus pentachloride (PCl5), without the need for urea or acids. The biopolymers were successfully phosphorylated, as confirmed by structural characterization techniques, including solid-state (NMR), xray diffraction (XRD), infrared spectroscopy (FTIR), and thermogravimetric analysis (TGA). Furthermore, detailed insights into the morphological and structural changes as well as the adsorption capabilities of the prepared materials, were thoroughly discussed using results from scanning electron microscopy (SEM), potential zeta measurement, and inductively coupled plasma spectrometer (ICP). Remarkably, the prepared bio-absorbents exhibited enhanced sorption properties for Methylene Blue (MB) through a wide pH range compared to their native forms. These findings shed light on how the molecular structure, reactivity, networking, and functional groups of P-Cellulose and P-Starch contribute to adsorptions efficiency. In addition to demonstrating the bioabsorbents regeneration and reuse, the prepared materials achieved heavy metal removal efficiencies of u to 70 %, significantly outperforming their native forms, which removed only 30 %. This highlights the critical role of phosphate groups and flexible networks in the uptake of contaminants from water.