Screening of GO-coated microporous polymeric filters for efficient paraquat removal: effect of support surface on membrane roughness and flux stability

TL;DR

This paper explores how different support materials affect the performance of graphene oxide membranes in removing paraquat, a pesticide, from water.

Contribution

The study introduces a systematic comparison of support materials to optimize GO membrane performance for efficient paraquat removal.

Findings

M-GO membranes showed the highest water flux and stable paraquat rejection over multiple cycles.

M-GO retained 66% of its initial flux after 42 hours of continuous operation.

Membranes performed well in simulated agricultural water with high ionic strength and organic matter.

Abstract

We report the fabrication and systematic evaluation of three thin-layer graphene oxide (GO) composite membranes prepared by vacuum-filtering a GO dispersion (nominal loading 0.42 mg cm−2) onto low-cost microporous supports (mixed cellulose ester, nylon, PVDF; 0.45 µm pore, 12 cm2). The membranes (M-GO, N-GO, P-GO) were characterized by AFM, SEM, XPS, and contact angle measurements to reveal support-dependent GO morphology and surface chemistry. At low (0.2 bar) transmembrane pressure (TMP), M-GO exhibited the highest steady-state water flux (425 ± 10 L m−2 h−1, n = 3), followed by N-GO and P-GO, while all GO-coated membranes achieved near-complete paraquat rejection (≤ LOD = 0.04 ppm) for feed concentrations of 0.1–1.0 ppm. Reusability tests on M-GO demonstrated ≥95% removal over five consecutive 1 h cycles with a flux recovery ratio (FRR) ≥ 65% after hydraulic flushing. In a 42 h continuous stability test at 0.2 bar, M-GO retained 66% of its initial flux and maintained ≥ 99% paraquat rejection. Tests in a simulated agricultural matrix (paraquat 5 ppm, 100 mM NaCl, 10 ppm humic acid) show a moderate flux decline (stabilizing at ∼55–60% of initial flux) with paraquat rejection > 90%, indicating robustness to ionic strength and natural organic matter. The head-to-head comparison isolates the decisive role of support surface roughness and porosity in governing GO layer formation, flux stability, and antifouling behavior, a pathway to low-pressure, high-flux membranes for cationic pesticide removal.

We report the fabrication and systematic evaluation of three thin-layer graphene oxide (GO) composite membranes prepared by vacuum-filtering a GO dispersion onto low-cost microporous supports (i.e. mixed cellulose ester, nylon, and PVDF).

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