Synthesis of bioinspired sorbent and their exploitation for methylene blue remediation

In this research article, novel starch phosphate grafted polyvinyl imidazole (StP-g-PIMDZs) was synthesized. Firstly, a phosphate group was attached to starch polymer via a phosphorylation reaction. Next, 1-vinyl imid-azole (VIMDZ) was grafted on the backbone of starch phosphate (StP) through a free radical polymerization reaction. The synthesis of these modified starches was confirmed by 1H NMR, 31P NMR and FT-IR techniques. The grafting of vinyl imidazole onto StP diminished the crystallinity. Due to the insertion of the aromatic imidazole ring, the StP-g-PIMDZs demonstrated greater thermal stability. The StP and StP-g-PIMDZs were used as sorbents for the adsorption of methylene blue dye (MBD) from the model solution. The maximum removal percentage for starch, StP, StP-g-PIMDZ 1, StP-g-PIMDZ 2 and StP-g-PIMDZ 3 was found to be 60.6%, 66.7%, 74.2%, 85.3 and 95.4%, respectively. The Pseudo second order kinetic model and Langmuir adsorption isotherm were best suited to the experimental data with R2 = 0.999 and 0.99, respectively. Additionally, the thermody-namic parameters showed that the adsorption process was feasible, spontaneous, endothermic and favored chemi-sorption mechanism.

Automated summary

Novel starch phosphate grafted polyvinyl imidazole (StP-g-PIMDZs) was synthesized by attaching a phosphate group to starch polymer and grafting 1-vinyl imidazole onto the backbone of starch phosphate. The modified starches showed diminished crystallinity and increased thermal stability. They also exhibited high adsorption capacity for methylene blue dye, with StP-g-PIMDZ 3 achieving a maximum removal percentage of 95.4%. The adsorption process followed a pseudo second order kinetic model and Langmuir adsorption isotherm, and was thermodynamically feasible, spontaneous, endothermic, and favored chemi-sorption mechanism.