Petroleum Chemistry (v.57, #6)

Fabrication of composite nanofiltration membranes from cellulose solutions in an [Emim]OAc–DMSO mixture by T. S. Anokhina; T. S. Pleshivtseva; V. Ya. Ignatenko; S. V. Antonov; A. V. Volkov (477-482).
The dissolution of cellulose in the [Emim]OAc ionic liquid mixed with DMSO as a cosolvent has been studied, and the possibility of fabricating composite cellulose membranes for the nanofiltration of organic media has been explored. It has been shown that the addition of DMSO to [Emim]OAc leads to a decrease in the dissolution time, which has a minimal value at a solvent ratio of 1 : 1. Composite membranes on a poly(ethylene terephthalate) support have been synthesized. The cellulose content in the casting solution was 6, 8, 12, or 16 wt %. It has been found that the rejection factor of the Remazol Brilliant Blue R dye (626 g/mol) varies from 42 to 82% depending on the composition of the casting solution.
Keywords: cellulose; ionic liquids; composite membranes; organic solvent nanofiltration; aprotic solvents

Hydrogen permeability and structure of vanadium alloy membranes by I. S. Sipatov; N. I. Sidorov; E. A. Pastukhov; I. E. Gabis; V. A. Piven; A. A. Esin; S. V. Pryanichnikov; A. A. Vostryakov (483-488).
Experimental data on hydrogen permeability through membrane alloys V85Ni15, V90Ti10, and V90Co10 (at %) are presented. Hydrogen permeability tests have been carried out in the temperature range of 623–873 K at pressures of ~4.5, 14, and 30 kPa. Results of X-ray diffraction analysis of samples are presented. Microstructure of the membrane alloys has been investigated before and after hydrogen permeability tests.
Keywords: hydrogen permeability; vanadium alloys; microstructure; membranes; grain size

Asymmetrical track-etched membranes prepared by double-sided irradiation on the DC-60 cyclotron by A. E. Kurakhmedov; I. A. Ivanov; V. V. Aleksandrenko; A. L. Kozlovskiy; E. Arkhangelsky; M. V. Zdorovets (489-497).
Asymmetric track-etched membranes based on polyethylene terephthalate have been prepared using two-sided irradiation on the heavy-ion accelerator DC-60. A process for cyclotron adjustment to bombardment of a polymer material has been described. A procedure for preparing asymmetric track-etched membranes with different pore lengths and sizes has been specified. The strength characteristics of the resulting membrane have been evaluated. It has been shown that the membrane can be used in processes in which the driving force is hydraulic or osmotic pressure.
Keywords: asymmetric track-etched membranes; cyclotron; polyethylene terephthalate; hydraulic pressure; osmotic pressure

A novel hybrid material based on polytrimethylsilylpropyne and hypercrosslinked polystyrene for membrane gas separation and thermopervaporation by G. S. Golubev; I. L. Borisov; E. G. Litvinova; V. S. Khotimsky; D. S. Bakhtin; A. V. Pastukhov; V. A. Davankov; V. V. Volkov (498-510).
To improve the membrane permeability and separation properties in gas separation processes and thermopervaporative (TPV) recovery of butanol from model fermentation mixtures, hybrid membranes based on polymers with an extremely high free fractional volume—polytrimethylsilylpropyne (PTMSP) and hypercrosslinked polystyrene (HCL-PS)—have been first prepared and experimentally studied. The composite membranes have been fabricated using the commercial sorbent Purolite Macronet MN-200 exhibiting high sorption capacity for organic solvents. It has been found that in the hybrid membranes, HCL-PS sorbent particles are nonuniformly distributed throughout the volume: they are located in the surface layer of the membrane. It has been shown that the introduction of a small amount of a modifying component (0.5–1.0 wt %) into the PTMSP matrix improves the time stability of transport properties and increase by a factor of 1.5–2 the permeability coefficients of the material to light gases (N2, O2, CO2, CH4) and butane vapor. It has been found that hybrid PTMSP/HCL-PS membranes have higher separation factors than those of PTMSP membranes in the TPV separation of a butanol/water binary mixture.
Keywords: thermopervaporation; gas permeability; PTMSP; HCL-PS; hybrid membranes; butanol

Mathematical modeling of concentration dependences of electric conductivity and diffusion permeability of anion-exchange membranes soaked in wine by M. V. Porozhnyy; V. V. Sarapulova; N. D. Pismenskaya; P. Huguet; S. Deabate; V. V. Nikonenko (511-517).
The formation of organic colloidal particles in the pores and on the surface (fouling) of membranes used in the food industry is a significant constraint on the further development of membrane technology. A model to describe the effect of these particles on electric conductivity and diffusion permeability has been proposed. It is based on a microheterogeneous two-phase model constructed in terms of the concepts of nonequilibrium thermodynamics and effective medium theory. The model takes into account the presence of two phases: (i) the gel phase comprising a polymer matrix and fixed ions whose charge is compensated for by mobile ions and (ii) the electrically neutral solution filling the intergel spaces. Each of the phases is characterized by intrinsic thermodynamic and kinetic parameters. The model takes into account changes in the values of these parameters caused by the formation of organic nanoparticles in meso- and macropores (fouling). It is assumed that the formation of colloidal particles in the intergel solution leads to a decrease in the ion mobility. In addition, these particles are capable of deprotonating a portion of the fixed ions and thereby decreasing the exchange capacity of the membrane. A high degree of hydration of these particles is responsible for an increase in the volume fraction of intergel spaces. Selection of relevant model parameters provides good agreement between calculation and experimental results.
Keywords: anion-exchange membrane; fouling; modeling; microheterogeneous model; colloidal particles

The influence of catalytic additives on electrochemical properties of bipolar membranes by N. V. Sheldeshov; V. I. Zabolotskii; A. V. Bespalov; N. V. Kovalev; N. V. Alpatova; A. V. Akimova; T. V. Mochalova; V. I. Kovaleva; A. Yu. Boyarishcheva (518-522).
The influence of organic, inorganic, and hybrid catalytic additives on the current–voltage characteristics of the bipolar region of industrial MB-1 and MB-3 bipolar membranes and analogues of an MB-2 bipolar membrane is investigated by the method of frequency spectrum of electrochemical impedance. It is shown that the introduction of compounds accelerating water dissociation reaction into the bipolar region makes it possible to obtain bipolar membranes with lower operating voltage when compared to industrial bipolar membranes.
Keywords: bipolar membrane; water dissociation; catalytic additive; frequency spectrum of electrochemical impedance; current–voltage characteristic

The possibility of using the seeded calcium carbonate precipitation technology developed previously by the author for the utilization of concentrates of existing reverse osmosis units has been explored. In modern reverse osmosis plants, scale inhibitors are used to prevent calcium carbonate scaling of membranes; the role of antiscalants consists of adsorption on the surface of forming crystals and slowing down their growth. The presence of antiscalants in the concentrate decreases the growth rate of the “seed” crystals and hampers the utilization of the concentrate. To increase the rate of crystallization, it is necessary to increase the supersaturation of the solution or increase the amount of seed crystals to be introduced. The dependence of the calcium carbonate growth rate in the antiscalant-containing concentrate on the added “seed” dose, recovery, and the pH has been studied. Various antiscalants have been compared in terms of performance, and their type most suitable for the process has been chosen. The results of comparison of the operating costs of a reverse osmosis plant involving concentrate utilization, depending on the antiscalant type used, are presented.
Keywords: concentrate; antiscalants; reverse osmosis plant; calcium carbonate crystallization; seed crystals; concentrate utilization

The fabrication of tubular microfiltration membranes from PKh18N15 corrosion-resistant steel by the method of radial isostatic pressing and magnetron plasma ion deposition of the surface layer is described. Scanning electron microscopy has been used to study the structure of the substrate and surface layers of the membrane. The flux values of tubular membranes have been found to be 1.39 × 10−8, 1.88 × 10−8, and 5.53 × 10−8 m3/(m2 Pa s) for the membranes with pore sizes of 1, 5, and 20 μm, respectively. The possibility of regenerating tubular membranes and restoring their productivity by backwashing has been shown. The service life of the membranes with different pore sizes has been determined during the treatment of make-up water for the sample preparation system of the primary circuit coolant of a pressurized water reactor (WWER).
Keywords: composite membranes; magnetron sputtering; stainless steel; service life; flux

Experimental data on the pressure gradient-dependent flux through UPM-50M, UFM-50, OPMN-P, and OFAM-K membranes in the separation of molasses distillery slop have been obtained. During the separation of the molasses distillery slop, a dynamic fluid membrane forms above the surface of the active layer on the test semipermeable membrane, which is compacted with increasing pressure and serves as an additional membrane. Evidence has been presented that the reverse osmosis membrane OFAM-K is superior for use at an effective working pressure of P = 4.0 MPa in the separation of the molasses distillery slops to the OPMN-P, UPM-50M, and UFM-50 membranes in terms of performance criteria (environmental friendliness, economy, import substitution, production of a discolored flow (volume) of permeate with good solute permeation and retention parameters) based on the results of statistical processing of experimental data.
Keywords: molasses distillery slop; dynamic membrane; rejection factor; flux; membrane