Osmium Recovery as Membrane Nanomaterials through 10–Undecenoic Acid Reduction Method

Abstract

The recovery of osmium from residual osmium tetroxide (OsO4) is a necessity imposed by its high toxicity, but also by the technical-economic value of metallic osmium. An elegant and extremely useful method is the recovery of osmium as a membrane catalytic material, in the form of nanoparticles obtained on a polymeric support. The subject of the present study is the realization of a composite membrane in which the polymeric matrix is the polypropylene hollow fiber, and the active component consists of the osmium nanoparticles obtained by reducing an alcoholic solution of osmium tetroxides directly on the polymeric support. The method of reducing osmium tetroxide on the polymeric support is based on the use of 10-undecenoic acid (10–undecylenic acid) (UDA) as a reducing agent. The osmium tetroxide was solubilized in t–butanol and the reducing agent, 10–undecenoic acid (UDA), in i–propanol, t–butanol or n–decanol solution. The membranes containing osmium nanoparticles (Os–NP) were characterized morphologically by the following: scanning electron microscopy (SEM), high-resolution SEM (HR–SEM), structurally: energy-dispersive spectroscopy analysis (EDAX), Fourier transform infrared (FTIR) spectroscopy. In terms of process performance, thermal gravimetric analysis was performed by differential scanning calorimetry (TGA, DSC) and in a redox reaction of an organic marker, p–nitrophenol (PNP) to p–aminophenol (PAP). The catalytic reduction reaction with sodium tetraborate solution of PNP to PAP yielded a constant catalytic rate between 2.04 × 10−4 mmol s–1 and 8.05 × 10−4 mmol s−1.

Simultaneous Release of Silver Ions and 10–Undecenoic Acid from Silver Iron–Oxide Nanoparticles Impregnated Membranes

“…45 µg/mL). This observation is in agreement with previous data, which showed that the loss of 10-undecenoic acid in a membrane can be reduced by using electrolyte additives (NaCl or NaNO3) [28][29][30].…”

“…These observations are in agreement with the previous results [28][29][30] and are correlated with the size and distribution of macro-porous pores of the membrane surface on which the dispersion of silver-containing oxide nanoparticles is impregnated in the first days of contact (Figure 8). At a longer operating time, a balance is achieved between the concentration of ions in the impregnated membrane and that of the ions in the receiving aqueous system.…”

“…The research in this study was initiated after the loss of membrane material, in the aqueous contact phases, of a liquid membrane system based on n-alkyl alcohols-oxide nanoparticles containing silver and 10-undecenoic acid [28][29][30]. If, in the considered membrane system, the loss of membrane material (silver ions and 10-undecenoic acid) was a disadvantage of using that device, the present research aims at the simultaneous release, either from a polymeric membrane or through an impregnated polymeric membrane, of the two chemical species.…”

Obtaining and Characterizing the Osmium Nanoparticles/n–Decanol Bulk Membrane Used for the p–Nitrophenol Reduction and Separation System

“…Among the metallic nanoparticles, those based on osmium have been relatively little studied [ 14 , 15 , 16 ], with one of the reasons being toxicity [ 17 ]. In reality, osmium is an inert metal with remarkable potential mechanical, thermal, electrical and catalytic properties, and its toxicity is related to osmium tetroxide that appears on the metal surface from contact with air [ 18 ].…”

“…In recent years, osmium nanoparticles have been deposited either on flat membranes with the aim of initiating reaction processes [ 14 ], or on hollow fiber membranes with the aim of increasing the contact surface between the phases of the membrane system [ 15 , 16 ].…”