Heterogenization of Polyoxometalates on the Surface of Plasma-Modified Polymeric Membranes

Abstract

Novel catalytic membranes have been prepared by linking phosphotungstic acid H3PW12O40 (W12), a polyoxometalate having interesting properties as photocatalyst, on the surface of plasma-modified membranes. Porous flat-sheet membranes made of polyvinylidene fluoride (PVDF) have been prepared by a phase-inversion technique induced by a nonsolvent. These membranes have been modified by plasma treatments on the surface to graft N-containing polar groups that are able to act as binding sites with W12 (PVDF−NH2−W12). A comparison of the surface and bulk properties of the native and modified PVDF membranes has been reported. Catalytic activity of the PVDF−NH2−W12 membranes has been evaluated in the aerobic degradation reaction of phenol in water. Catalytic tests have been carried out in a membrane reactor operating in continuous mode. Better catalytic performances have been observed for the W12 heterogenized on PVDF membrane than for W12 in a homogeneous phase. Moreover, PVDF−NH2−W12 membranes have given proof of their complete stability under photooxidation conditions and their good recycle. This study has shown the possibility of heterogenizing catalysts by a controlled modification of the membrane surface via a plasma technique. This new method is very versatile and can be easily extended to other catalysts. Further studies are actually in progress with other catalysts belonging to the polyoxometalates group.

Preparation of multilayer films containing a crown heteropolyanion and an osmium functionalised pyrrole monomer

“…As a result, they have become promising candidates for functional ultrathin films on a variety of substrate surfaces. The resulting surface based systems have exhibited electrocatalytic properties towards the reduction of various substrates such as NO 2 À , NO, BrO 3 À , IO 3 À , H 2 and H 2 O 2 as well as electrochromic properties [11][12][13][14][15]. In addition, their possible potential application as a pH-sensitive probe was also reported [16,17].…”

Membrane Reactors: Advanced Systems for Intensified Chemical Processes

“…In addition, polymeric catalytic membranes have also been prepared by immobilizing sodium deacatungstate and phosphotungstic acid (H 3 PW 12 O 40 ) on the surface of PVDF membranes modified by Ar/NH 3 plasma discharges [65].…”

Simulating the Favorable Aggregation of Monolacunary Keggin Anions

“…33,34 Secondly, dynamic electrostatic interactions are certain to play a primary role in the supramolecular applications of POMs. These include encapsulation into dendrimers, 35,36 surfactants, 37 and cyclodextrins; 38 their use in ionic liquids; [39][40][41][42] as well as their noncovalent aggregation on surfaces 43,44 and as vescicles, [45][46][47][48] which occurs notwithstanding their high negative charge.…”