Abstract:Regardless of the type of liquid membrane (LM) (Bulk Liquid Membranes (BLM), Supported Liquid Membranes (SLM) or Emulsion Liquid Membranes (ELM)), transport and separation of chemical species are conditioned by the operational (OP) and constructive design parameters (DP) of the permeation module. In the present study, the pH of the aqueous source phase (SP) and receiving phase (RP) of the proposed membrane system were selected as operational parameters. The mode of contacting the phases was chosen as the conve… Show more
“…Catalytic systems based on osmium nanoparticles, coupled with polymer or liquid membrane processes, have been less frequently reported [19][20][21]30,31]. In these hybrid membrane-catalytic processes, p-nitrophenol is reduced to p-aminophenol with osmium nanoparticles.…”
Section: Discussionmentioning
confidence: 99%
“…This hybrid process involves both the conversion of p-nitrophenol in the source phase and the separation of p-aminophenol in the receiving phase through a membrane process. Previously, bulk liquid membranes based on osmium nanoparticles were tested [20,21,30], as well as liquid membranes on support (SLMs) [19,31].…”
Section: Discussionmentioning
confidence: 99%
“…The reactive membrane systems recently tested for the reduction and separation of p-nitrophenol (pNP) from source aqueous solutions use polymers as membrane phases (Figure 1c) or medium-chain n-alcohols, in which nanoparticles are dispersed [19][20][21][22][23].…”
Section: Introductionmentioning
confidence: 99%
“…The reduction reaction takes place in a column-type reactor fed at the base with the emulsion containing the receiving phase, and the source phase is introduced either at the base of the column (co-current) (Figure 7a) or at the top (counter-current) (Figure 7b). The conversion (η%) or extraction efficiency (EE%) for the species of interest using the concentration of the solutions [19][20][21] was calculated as follows:…”
Membrane materials with osmium nanoparticles have been recently reported for bulk membranes and supported composite membrane systems. In the present paper, a catalytic material based on osmium dispersed in n–decanol (nD) or n–dodecanol (nDD) is presented, which also works as an emulsion membrane. The hydrogenation of p–nitrophenol (PNP) is carried out in a reaction and separation column in which an emulsion in the acid-receiving phase is dispersed in an osmium nanodispersion in n–alcohols. The variables of the PNP conversion process and p–aminophenol (PAP) transport are as follows: the nature of the membrane alcohol, the flow regime, the pH difference between the source and receiving phases and the number of operating cycles. The conversion results are in all cases better for nD than nDD. The counter-current flow regime is superior to the co-current flow. Increasing the pH difference between the source and receiving phases amplifies the process. The number of operating cycles is limited to five, after which the regeneration of the membrane dispersion is required. The apparent catalytic rate constant (kapp) of the new catalytic material based on the emulsion membrane with the nanodispersion of osmium nanoparticles (0.1 × 10−3 s−1 for n–dodecanol and 0.9 × 10−3 s−1 for n–decanol) is lower by an order of magnitude compared to those based on adsorption on catalysts from the platinum metal group. The advantage of the tested membrane catalytic material is that it extracts p–aminophenol in the acid-receiving phase.
“…Catalytic systems based on osmium nanoparticles, coupled with polymer or liquid membrane processes, have been less frequently reported [19][20][21]30,31]. In these hybrid membrane-catalytic processes, p-nitrophenol is reduced to p-aminophenol with osmium nanoparticles.…”
Section: Discussionmentioning
confidence: 99%
“…This hybrid process involves both the conversion of p-nitrophenol in the source phase and the separation of p-aminophenol in the receiving phase through a membrane process. Previously, bulk liquid membranes based on osmium nanoparticles were tested [20,21,30], as well as liquid membranes on support (SLMs) [19,31].…”
Section: Discussionmentioning
confidence: 99%
“…The reactive membrane systems recently tested for the reduction and separation of p-nitrophenol (pNP) from source aqueous solutions use polymers as membrane phases (Figure 1c) or medium-chain n-alcohols, in which nanoparticles are dispersed [19][20][21][22][23].…”
Section: Introductionmentioning
confidence: 99%
“…The reduction reaction takes place in a column-type reactor fed at the base with the emulsion containing the receiving phase, and the source phase is introduced either at the base of the column (co-current) (Figure 7a) or at the top (counter-current) (Figure 7b). The conversion (η%) or extraction efficiency (EE%) for the species of interest using the concentration of the solutions [19][20][21] was calculated as follows:…”
Membrane materials with osmium nanoparticles have been recently reported for bulk membranes and supported composite membrane systems. In the present paper, a catalytic material based on osmium dispersed in n–decanol (nD) or n–dodecanol (nDD) is presented, which also works as an emulsion membrane. The hydrogenation of p–nitrophenol (PNP) is carried out in a reaction and separation column in which an emulsion in the acid-receiving phase is dispersed in an osmium nanodispersion in n–alcohols. The variables of the PNP conversion process and p–aminophenol (PAP) transport are as follows: the nature of the membrane alcohol, the flow regime, the pH difference between the source and receiving phases and the number of operating cycles. The conversion results are in all cases better for nD than nDD. The counter-current flow regime is superior to the co-current flow. Increasing the pH difference between the source and receiving phases amplifies the process. The number of operating cycles is limited to five, after which the regeneration of the membrane dispersion is required. The apparent catalytic rate constant (kapp) of the new catalytic material based on the emulsion membrane with the nanodispersion of osmium nanoparticles (0.1 × 10−3 s−1 for n–dodecanol and 0.9 × 10−3 s−1 for n–decanol) is lower by an order of magnitude compared to those based on adsorption on catalysts from the platinum metal group. The advantage of the tested membrane catalytic material is that it extracts p–aminophenol in the acid-receiving phase.
To promote the implementation of liquid membrane separations in industry, we have previously proposed extraction methods called three- and multi-phase extraction. The three-phase multi-stage extraction is carried out in a cascade of bulk liquid membrane separation stages, each comprising two interconnected (extraction and stripping) chambers. The organic liquid membrane phase recycles between the chambers within the same stage. In multi-phase extraction, each separation stage includes a scrubbing chamber, located between the extraction and stripping chambers. The three- and multi-phase multi-stage extraction technique can be realized either in a series of mixer–settler extractors or in special two- or multi-chamber extraction apparatuses, in which the convective circulation of continuous membrane phase between the chambers takes place due to the difference in emulsion density in the chambers. The results of an experimental study of the extraction of phenol from sulfuric acid solutions in the three-phase extractors with convective circulation of continuous membrane phase are presented. Butyl acetate was used as an extractant. The stripping of phenol from the organic phase was carried out with 5–12% NaOH aqueous solutions. The prospects of using three-phase extractors for wastewater treatment from phenol are shown. An increase in the efficiency of three-phase extraction can be achieved by carrying out the process in a cascade of three-phase apparatuses.
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