Osmium Nanoparticles-Polypropylene Hollow Fiber Membranes Applied in Redox Processes.

Ovidiu Oprea,Aurelia Cristina Nechifor,Florentina Mihaela Păncescu,Gheorghe Nechifor,Paul Constantin Albu,Alexandra Raluca Grosu,Szidonia-Katalin Tanczos,Andreia Pîrțac,Constantin Bungău,Vlad-Alexandru Grosu

doi:10.3390/nano11102526

Abstract

Composite membranes play a very important role in the separation, concentration, and purification processes, but especially in membrane reactors and membrane bioreactors. The development of composite membranes has gained momentum especially through the involvement of various nanoparticles, polymeric, oxide, or metal, that have contributed to increasing their reactivity and selectivity. This paper presents the preparation and characterization of an active metal nanoparticle-support polymer type composite membrane, based on osmium nanoparticles obtained in situ on a polypropylene hollow fiber membrane. Osmium nanoparticles are generated from a solution of osmium tetroxide in tert-butyl alcohol by reduction with molecular hydrogen in a contactor with a polypropylene membrane. The composite osmium-polypropylene hollow fiber obtained membranes (Os-PPM) were characterized from the morphological and structural points of view: scanning electron microscopy (SEM), high resolution SEM (HR-SEM), energy dispersive spectroscopy analysis (EDAX), X-ray diffraction analysis (XRD), Fourier transform Infrared (FTIR) spectroscopy, thermal gravimetric analysis, and differential scanning calorimetry (TGA, DSC). The process performance was tested in a redox process of p-nitrophenol and 10-undecylenic (10-undecenoic) acid, as a target substance of biological or biomedical interest, in solutions of lower aliphatic alcohols in a membrane contactor with a prepared composite membrane. The characteristics of osmium nanoparticles-polypropylene hollow fiber membranes open the way to biological and biotechnological applications. These membranes do not contaminate the working environment, operate at relatively low temperatures, provide a large contact area between reactants, allow successive oxidation and reduction operations in the same module, and help to recover the reaction mass by ultrafiltration. The results obtained show that the osmium-polypropylene composite membrane allows the reduction of p-nitrophenol or the oxidation of 10-undecylenic acid, the conversion depending on the concentration in the lower aliphatic alcohol, the nature of the lower aliphatic alcohol, and the oxidant or reducing flow through the membrane contactor.

Highlights

The development of membranes and membrane processes involving compositeThe development of membranes and membrane processes involving composite memmembranes has gained great importance with the progress made in obtaining nanopartibranes has gained great importance with the progress made in obtaining nanoparticles cles with a well-controlled composition, shape, and size distribution [1,2]
This paper presents the preparation and characterization of a composite membrane of active metal nanoparticle-support polymer type, based on osmium nanoparticles obtained in situ on a polypropylene hollow fiber membrane and its use in the transformation of
The present study used osmium nanoparticles-polypropylene hollow fiber membranes selected from previous experiments on osmium nanoparticles-polymer membranes [63], which included three polymers of different hydrophobicity: polyethylene, polysulfone, and cellulose acetate

Summary

Introduction

The development of membranes and membrane processes involving composite memmembranes has gained great importance with the progress made in obtaining nanopartibranes has gained great importance with the progress made in obtaining nanoparticles cles with a well-controlled composition, shape, and size distribution [1,2]. The nature nature of the nanoparticles used in obtaining membranes is of overwhelming importance of the nanoparticles used in obtaining membranes is of overwhelming importance for selecfor selectivity, reactivity, or effect on membrane processes (Figure 1). Polymeric nanoparticles noparticles basedoxide, on carbon, oxide, metals, or their have compounds have used for the based on carbon, metals, or their compounds been used forbeen the preparation preparation of composite membranes both in separation processes and in various reaction of composite membranes both in separation processes and in various reaction processes: processes: esterification, etherification, reduction, and oxidation [2,3,4]. Intense intense studies have followed the influence of the size and shape of nanoparticles from studies have followed the influence of the size and shape of nanoparticles from a certaina certain material on the performance of composite membranes [5,6]

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