Aqueous-phase synthesis of PAA in PVDF membrane pores for nanoparticle synthesis and dichlorobiphenyl degradation
Introduction
Traditionally, membranes are used for the separations based on size exclusion, solution diffusion or Donnan exclusion [1]. However, membrane modification with novel, advanced functional groups [2] or layer-by-layer deposition of polyelectrolytes and the growth of polymer brushes [3] can extend their area of application toward advanced separations, development of biomaterials or catalysis. In the field of catalysis in particular, there is a growing interest in detoxification of organic chlorinated compounds from aqueous streams. Chlorinated organic compounds constitute a large group of pollutants of international concern due to their high toxicity, persistence and various sources of distribution in the environment.
In recent years, zero-valent nanoscale metal (especially iron) particles have attracted a growing attention in groundwater remediation of chlorinated solvents [4], [5]. However, iron nanoparticles tend to agglomerate in water rapidly to form micron size or larger aggregates, thus losing their reactivity. Various techniques have been employed to control the particle size, by using additives [6], [7] controlled seed mediated synthesis [8], [9] or coating with a protective layer [10]. For a more rapid and complete dechlorination, a second element is often added, resulting in creation of bimetallic nanoparticles. In these systems, the first metal (most commonly Fe, but also Mg, Sn, etc.) is an electron donor to degrade the organic compound and the second metal (usually a more noble metal such as Pd or Ni) promotes the reactivity through hydrogenation, acting as a catalyst. Several bimetallic systems that are used for dechlorination of toxic chlorinated organic compounds, have been reported in the literature: Fe/Ni [11], [12], Ni(B)/Fe(B) [13], Fe/Pd [14], [15], [16], [17], [18], [19], Mg/Pd [20], [21], [22], Sn/Pd [23].
In order to minimize the particle agglomeration and loss, another approach is to synthesize supported nanoparticles on activated carbon [24], [25], resins [23] or membranes, as substrates. Among these, membranes have a distinct advantage because of ease of functionalization and the ability to be operated under convective flow conditions (filtration), thus eliminating the mass transfer issues often encountered in diffusive (batch) mode operation. Membranes have received a special attention (including our research group) and have been successfully employed as platforms for nanoparticle synthesis. Membrane's open structure and high internal surface area ensure a high nanoparticle loading and easy active site accessibility. The most common membrane materials used for this purpose are: cellulose acetate [11], [26], hydrophilized polysulfone [27], polyacrylic acid-modified polyether sulfone [28], [29] and polyvinylidene fluoride [30], [31], [32]: these membranes have proven to be very efficient for the degradation of the organic chlorinated compounds from water.
In recent years there has been a great interest in our laboratory in PVDF membrane modification with PAA by dip coating or solvent phase in situ polymerization of acrylic acid, with subsequent Fe/Pd nanoparticle incorporation [30], [31], [33]. Dechlorination studies using a variety of toxic chlorinated organic compounds were performed and a mathematical model was developed. Currently we investigate a method of PAA modification of PVDF membranes using aqueous-phase polymerization (no organic solvent use) and study the nanoparticle longevity and stabilization by protecting the Fe/Pd nanoparticle surface.
The main goals of present study are: (i) synthesize bimetallic Fe/Pd nanoparticles within the pores of a functionalized membrane (polyacrylic acid-coated polyvinylidene fluoride) using green chemistry, (ii) characterize the membrane and nanoparticles characterization, (iii) study the reactivity toward a target toxic organic compound, 2,2′-dichlorobiphenyl, (iv) evaluate nanoparticle stability during operation (dechlorination) and regeneration, and (v) demonstrate operation under convective flow conditions.
Section snippets
Materials
All chemicals used were of reagent grade. Ferrous chloride, deionized ultrafiltered (DIUF) water were purchased from Fisher Scientific. Potassium persulfate was purchased from EM Science and ethylene glycol (EG) from Mallinckrodt. Acrylic acid and potassium tetrachloropalladate (II) were purchased from Sigma–Aldrich. Naphthalene-d8 and 2,2′-dichlorobiphenyl (DiCB) were purchased from Ultra Scientific. Hydrophilic polyvinylidene fluoride (PVDF) microfiltration membranes (DVPP) with a thickness
Functionalized membrane characterization
The functionalization of the PVDF membranes with PAA was characterized by FTIR-ATR spectroscopy and stimulus-responsive water flux to pH. The organic functionalities for the hydrophilized PVDF and PAA-coated PVDF membranes were studied by FTIR-ATR spectroscopy. The PAA-coated PVDF membrane shows a peak at 1710 cm−1, which is not present in the spectrum for the blank PVDF membrane. This peak is due to the presence of CO bond stretching in carboxylic acid groups, indicating successful PAA
Conclusions
In this paper, the synthesis of an effective dechlorination system (using green chemistry) that incorporates Fe/Pd nanoparticles into a PAA-coated PVDF membrane, is presented. High active site (Pd) accessibility and fast dechlorination rates at a relatively low metal loading (about one order of magnitude lower, compared to solution phase), are among the major advantages of this method. The dechlorination rates are highly dependent on Pd content. The immobilization of Fe2+ on the Fe/Pd-modified
Acknowledgements
This study was supported by the National Institute of Environmental Health Sciences/National Institutes of Health Superfund Research Program (P42ES07380).
References (37)
Advanced functional polymer membranes
Polymer
(2006)- et al.
Remediation of PCB contaminated soils using iron nanoparticles
Chemosphere
(2007) - et al.
Hydrodechlorination of trichloroethene using stabilized Fe–Pd nanoparticles: reaction mechanism and effects of stabilizers, catalysts and reaction conditions
Appl. Catal. B: Environ.
(2008) - et al.
Catalytic dechlorination of monochlorobenzene with a new type of nanoscale Ni(B)/Fe(B) bimetallic catalytic reductant
Chemosphere
(2008) - et al.
Nanoscale Pd/Fe bimetallic particles: catalytic effects of palladium on hydrodechlorination
Appl. Catal. B: Environ.
(2007) - et al.
Dechlorination kinetics of monochlorobiphenyls by Fe/Pd: effects of solvent, temperature, and PCB concentration
Appl. Catal. B: Environ.
(2008) - et al.
Dechlorination of hexachlorobenzene by using nanoscale Fe and nanoscale Pd/Fe bimetallic particles
Colloids Surf. A
(2009) - et al.
Supported Pd/Sn bimetallic nanoparticles for reductive dechlorination of aqueous trichloroethylene
Chemosphere
(2009) - et al.
Degradation of trichloroethylene by zero-valent iron immobilized in cationic exchange membrane
Desalination
(2008) - et al.
Preparation and characterization of PAA/PVDF membrane-immobilized Pd/Fe nanoparticles for dechlorination of trichloroacetic acid
Water Res.
(2008)
Development and characterization of poly(vinylidene fluoride)-poly (acrylic acid) pore-filled pH-sensitive membranes
J. Membr. Sci.
In vitro investigation of potential application of pH-sensitive poly(vinylidene fluoride)–poly(acrylic acid) pore-filled membranes for controlled drug release in ruminant animals
J. Membr. Sci.
Creation of functional membranes using polyelectrolyte multilayers and polymer brushes
Langmuir
Nanotechnology and water treatment: applications and emerging opportunities
Crit. Rev. Microbiol.
Stabilization of Fe–Pd nanoparticles with sodium carboxymethyl cellulose for enhanced transport and dechlorination of trichloroethylene in soil and groundwater
Ind. Eng. Chem. Res.
Synthesis of iron nanoparticles via chemical reduction with palladium seeds
Langmuir
Precise seed-mediated growth and size-controlled synthesis of palladium nanoparticles using a green chemistry approach
Langmuir
Cited by (99)
Fabrication of 3D-printed PLA filter with immobilized Prussian blue for aqueous cesium removal
2023, Journal of Water Process EngineeringNew insights of g-C<inf>3</inf>N<inf>4</inf>/Bi<inf>2</inf>WO<inf>6</inf> nanocomposite surface assembled on PVDF hybrid membrane for the treatment of pirimicarb pesticides
2023, Journal of the Taiwan Institute of Chemical EngineersFabrication of antifouling two-dimensional MoS<inf>2</inf> layered PVDF membrane: Experimental and density functional theory calculation
2022, Separation and Purification TechnologyRecent trends in application of nanoscale zero-valent metals and metal single atoms in membrane processes
2022, Journal of Environmental Chemical EngineeringReduction of nitrobenzene by a zero-valent iron microspheres/polyvinylidene fluoride (mZVI/PVDF) membrane
2022, Separation and Purification TechnologyCurrent trends of nano-enhanced polymeric membranes for water and wastewater reclamation
2022, Novel Materials for Environmental Remediation Applications: Adsorption and Beyond