PREPARATION METHOD OF NZVI-PVDF HYBRID FILMS WITH CATION-EXCHANGE FUNCTION FOR REDUCTIVE TRANSFORMATION OF CR(VI)

Xiangyu Wang,Shan Cong

doi:10.3846/16486897.2017.1339048

Abstract

Poly (vinylidene fluoride) (PVDF) microporous film was successfully synthesized and functionalized by poly acrylic acid (PAA) for immobilization of nanoscale zero-valent iron (NZVI). PAA was innovatively introduced onto PVDF film via in situ polymerization of acrylic acid (AA) and followed by ion exchange procedure. The as-prepared PAA/PVDF-NZVI hybrids (PPN) were characterized in terms of morphology (SEM) and surface functional groups (FTIR). FTIR spectra confirms the functionalization of PVDF film by coating of PAA within its micropores. And SEM images suggested that NZVI were well immobilized onto the surface of the support. Over the reaction course, the resultant PPN hybrids demonstrated high reactivity, excellent stability and reusability for Cr(VI) removal. Results showed that lower pH and initial concentration facilitated the removal of Cr(VI) by PPN. Compared with bare NZVI, PAA/PVDF film-immobilized NZVI resulted in a lower activation energy for Cr(VI) removal, indicating that Cr(VI) reduction process with PPN is a surfacecontrolled chemical reaction. Moreover, a two-parameter pseudo-first-order model was provided and well-described the reaction kinetics of Cr(VI) over PPN under various conditions.

Highlights

The widespread use of toxic heavy metals in industrial processes constitutes the primary source for water pollution and it’s accumulating in the ecosystem causes serious risk to the environment and the living systems
The activation energy of Cr(VI) reduction with pristine nanoscale zero-valent iron (NZVI) was 46.31 kJ mol−1, indicating that the NZVI supported by poly acrylic acid (PAA)/Polyvinylidene fluoride (PVDF) films result in a lower activation energy, and that a faster chemical process during the Cr(VI) reduction by pristine NZVI can be anticipated through the approach of Cr(VI) immobilization with PAA/PVDF films
SEM characterization of PAA/PVDFNZVI hybrids (PPN) indicates that the synthesized nanoscale zero-valent iron particles were homogeneously dispersed in the film

Summary

Introduction

The widespread use of toxic heavy metals in industrial processes constitutes the primary source for water pollution and it’s accumulating in the ecosystem causes serious risk to the environment and the living systems. Due to its excellent physical and chemical properties (including large specific surface area, high reactivity, and low-cost), NZVI was chosen to be remediation agent for treatment of Cr(VI) wastewater. The NZVI particles reduce toxic heavy metals through oxidation of the Fe0 core and subsequent allocation of electrons to the pollutant at a relatively fast reaction rate because of its larger specific surface area and higher surface reactivity (Wang et al 2008; Shu et al 2007, 2010; Shih et al 2011; Qiu et al 2013).

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