Reusable Nanocomposite Membranes for Highly Efficient Arsenite and Arsenate Dual Removal from Water

Nanocomposite membranes (NCMs) of poly(vinylidene fluoride-hexafluoropropylene),
PVDF-HFP, with different yttrium carbonate and magnetite loadings,
are prepared, and their dual adsorption capacity over neutral arsenite
and anionic arsenate species is evaluated. The nanoparticles (NPs) and the
corresponding NCMs are fully characterized in morphology, microstructure,
thermal, and surface properties. The nanocomposite membranes present a
micrometric porous structure with a homogeneous distribution of the active
nanoparticles. Chemical, thermal, and water-contact angle characteristics of
the NCMs point out that they maintain the chemical and thermal stability
of the polymer while improving the wettability. Arsenic removal depends on
NP loading and pH of the media. For instance, efficiencies close to 100%
are achieved for arsenate species under acidic conditions, while adsorption
capacity over arsenite is also incremented above 80%. Fe3O4/PVDF-HFP
nanocomposite shows a dual affinity for the adsorption of As(III) and As(V)
species, with the maximum adsorption capacities of 92.82 and 137.08 mg g−1,
respectively. In addition, both NCMs are easily activated and reused without
significant efficiency loss. Consequently, the nanocomposite membranes represent
low-cost, reusable, and efficient water remediation systems suitable for
the long-term removal of As(III) and As(V) under conditions mimicking real
polluted surface and groundwater