Arsenic (V) removal with modifiable bulk and nano p(4-vinylpyridine)-based hydrogels: The effect of hydrogel sizes and quarternization agents

Macrogels and nanogels (5 × 6 mm and 370 nm dimensions, respectively) based on 4-vinylpyridine (p-(4VP)) were prepared using redox and microemulsion techniques. The p(4-VP)-based materials were quaternized with HCl/alkyhalides having different chain lengths to tune the charges (macro and nanogels) and size of nanogels. By developing positive charge on the p(4-VP) materials, they behaved as ion exchangers and used in removal of As(V) from aqueous environments. The prepared p(4-VP) materials were also rendered responsive to magnetic field by in situ incorporation of magnetic metal nanoparticles inside macro p(4-VP) hydrogels and by encapsulation of separately prepared magnetic ferrites by nanosized p(4-VP) particles. Nanoparticles quaternized with HCl (p(4-VP)-HCl) (1 g) removed over 95% of As(V) from a stock solution (10 mg L− 1, 1000 mL) in 15 min whereas bulk hydrogels removed > 82% of the As(V) from an equivalent solution in ~ 12 h. Parameters effecting the As(V) removal, including pH, temperature and ionic strength, were also investigated. The synthesized magnetic p(4-VP) composites could be reused after elution with NaOH and regeneration with quaternization agents; these procedures were facilitated using an externally applied magnetic field. The Langmuir and Freundlich adsorption isotherms were also applied to study the removal of As(V) from aqueous environments.

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► As(V) removal using smart macro and nanosized p(4-VP) based hydrogels.
► The effect of hydrogel size and quarternization agents on As(V) removal from aqueous media by modifiable benign hydrogels.
► The investigation of the parameter such as pH, T and ionic strength on As(V) removal.
► The reusability of modified p(4-VP) based materials in toxic metal elimination.