Polyvinyl alcohol–alginate ferrophoto gels for mercury(II) removal

• γ-Fe2O3 nanoparticles was synthesized by coprecipitation method.
• The robust PVA–alginate magnetic beads have superior photocatalytic performance.
• The highly porous structure allows easy diffusion of Hg(II) into the interiors of beads.
• 96% of Hg(II) was removed within 270 min at pH 11 under sunlight.
• The removal of Hg(II) well fitted with Langmuir–Hinshelwood (L–H) kinetic model.

Maghemite (γ-Fe2O3) nanoparticles were embedded in polyvinyl alcohol (PVA) and alginate matrix to produce beads that could be easily recovered with external magnetic field after treating mercury, Hg(II) in aqueous solution. 96% of Hg(II) was removed in 4 h under sunlight, at pH 11 and 16% (v/v) of photocatalyst dosage. FESEM results revealed that the beads possessed significant superporosity structure that greatly supported mass transfer of Hg(II) inside the beads. The removal of Hg(II) fitted well with Langmuir–Hinshelwood (L–H) model exhibiting R2 (correlation coefficient) value of 0.9771. Thus, this study proved that it was feasible to treat Hg(II) solution with γ-Fe2O3–PVA–alginate beads.

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