Photocatalytically active layered double hydroxide-PVDF composite membranes for effective remediation of dyes contaminated water

Abstract

In this work, polyvinylidene fluoride (PVDF) intercalated CuFe layered double hydroxides (LDH) membranes were fabricated and investigated for UV-LED/persulfate degradation of methylene blue (MB), crystal violet (CV), methyl orange (MO), and Eriochrome black T (EBT) dyes from water. The PVDF-CuFe membrane exhibited improved heterogeneity, surface functionality (CuO, Fe-O, Cu-O-Fe), surface roughness, and hydrophilicity. The process parameters were optimized by response surface methodology, and maximum MB removal (100%) was achieved within 45.22-178.5 min at MB concentration (29.45-101.93 mg/L), PP concentration (0.5-2.41 g/L) and catalyst dosage (1.84-1.95 g/L). The degradation kinetics was well described by a pseudo-first-order model (R² = 0.982) and fast reaction rate (0.029-0.089/min). The MB dye degradation mechanism is associated with HO·/SO₄^•- reactive species generated by Fe³⁺/Fe²⁺ or Cu²⁺/Cu⁺ in PVDF-CuFe membrane and PP dissociation. The PVDF-CuFe membrane demonstrated excellent recyclability performance with a 12% reduction after five consecutive cycles. The catalytic membrane showed excellent photocatalytic degradation of crystal violet (100%), methyl orange (79%), and Eriochrome black T (60%). The results showed that UV-LED/persulfate-assisted PVDF-CuFe membranes can be used as a recyclable catalyst for the effective degradation of dye-contaminated water streams.

Keywords: Dye pollution; Nanoparticles; Photocatalytic membranes: response surface methadology; Photodegradation.