An ethylene glycol (EG)–acetone (AC) system is studied via differential scanning calorimetry in the −140 to +40°С range of temperatures. A phase diagram is plotted over the range of concentrations. It is found that the mixtures in the system are supercooled by more than 30°C. Low-temperature melting is recorded in the region around −98°C, which corresponds to the eutectic point temperature. The devitrification of rapidly cooled samples is observed in the range of concentrations up to ~21 mol % AC, and the temperature of devitrification is determined ( T g ~ −120°C). The plotted phase diagram of the EG–AC system is compared to a water–acetone phase diagram.

In the process of opening phosphate rocks and extracting the main component by acid ex-traction, a stage of isolation of the insoluble residue from the obtained suspensions by filtration is necessary. This will ensure an increase in the concentration of nutrients in the products of pro-cessing natural phosphorites used as model minerals. The insoluble residue on the filter baffle is a filter layer, the dense structure of which prevents the effective process of separating the liquid-solid system. In order to intensify the filtration process of nitric acid suspension based on low-quality high-siliceous phosphorite of the Polpinsky deposit, the effect of sulfate additives: sulfuric acid, ammonium sulfate and potassium sulfate on the structure of the sediment and, accordingly, the filtration time of the suspension and washing of the sediment was studied. The content of the ad-ministered additives varied in the range of 10 -30 weight %. The results of the study of the micro-structure of sediments - vertical cross-section and their surface obtained using the scanning elec-tron microscopy method allowed us to establish that the introduction of the studied additives leads to an increase in the porosity of the layer due to the formation of large druses from single crystals of calcium sulfate dihydrate -gypsum. This improves the filtration properties of the sediment layer, reducing the filtration and washing time. It should be noted that, all other things being equal, the effectiveness of potassium sulfate additives is higher in comparison with sulfuric acid and ammo-nium sulfate additives. Its advantage lies not only in improving the rheological properties of sus-pensions, but also in the presence of potassium in the system as a nutrient component during the processing of nitric acid extract for complex fertilizers. The effective concentration of potassium sulfate in the system was experimentally established at 20 weight. %. At the same time, the maxi-mum value of the filtration rate of the suspension is 0.537 m3/(m2 center dot h), which is 1.08 and 1.03 times higher compared to the filtration of suspensions containing ammonium sulfate and sulfuric acid, respectively. The revealed trend extends to the precipitation washing rate -the maximum value corresponds to 0.750 m3/(m2 center dot h), which exceeds the corresponding comparison samples by 1.1 and 1.15 times.

In this paper, the process of film distillation with a porous condensing surface (FD-PCS) is studied as applied to the tasks of concentration of lithium-containing solutions. Concentration of solutions is a part of a three-stage lithium extraction cycle that includes softening of the brine by the precipitation of Ca2+/Mg2+ cations with sodium carbonate (calculated in PHREEQC) followed by an integrated system consisting of a membrane distillation unit and a crystallizer (deposition of NaCl) and membrane extraction (extraction of Li+). The productivity flows of the film distillation module are investigated (4.15–7.49 kg m−2 h−1 at the temperatures of heating of the evaporation surface of 60 and 80°C, respectively). The complex operation of the three-stage system is modeled in Simulink/MATLAB. The modeling of the process based on the experimental and published data shows a higher efficiency of film distillation with a porous condensing surface in comparison with membrane distillation with a porous condensing surface (4.2 kg of lithium versus 1.4 kg over two months of stationary operation of the system).

For the first time, membranes based on poly(1-trimethylsilyl-1-propyne) (PTMSP) with 5–50 wt% loading of hyper-crosslinked polystyrene sorbent particles (HCPS) were obtained; the membranes were investigated for the problem of effective removal of volatile organic compounds from aqueous solutions using vacuum pervaporation. The industrial HCPS sorbent Purolite Macronet™ MN200 was chosen due to its high sorption capacity for organic solvents. It has been found that the membranes are asymmetric when HCPS content is higher than 30 wt%; scanning electron microscopy of the cross-sections the membranes demonstrate that they have a clearly defined thin layer, consisting mainly of PTMSP, and a thick porous layer, consisting mainly of HCPS. The transport and separation characteristics of PTMSP membranes with different HCPS loading were studied during the pervaporation separation of binary and multicomponent mixtures of water with benzene, toluene and xylene. It was shown that the addition of HCPS up to 30 wt% not only increases the permeate fluxes by 4–7 times, but at the same time leads to 1.5–2 fold increase in the separation factor. It was possible to obtain separation factors exceeding 1000 for all studied mixtures at high permeate fluxes (0.5–1 kg/m2∙h) in pervaporation separation of binary solutions.

This work is aimed at investigating a new process of film distillation with a membrane condenser (FDMC) for obtaining fresh water from a reverse osmosis concentrate. The behavior of a number of structural materials during their exposure for 4.5 months in the open air and in sea water has been investigated. In the Simulink/MATLAB program, a model of the FDMC unit with the possibility of using solar radiation as a renewable energy source has been built. The operation of the unit for one month was simulated and it was shown that the area of solar collectors has the greatest influence on the volume of water received during a month of operation. The area of the evaporator has little effect on the overall process performance, but it can reduce the initial costs while maintaining the same payback period. Modeling showed that the recovery of distilled water decreases by 2–3% (from ~71–72 to ~69%) with a decrease in the NaCl concentration of the output stream from 26 to 24 wt %. The mode with a lower concentration of the output solution was found to be optimal due to the absence of both the risk of pipeline clogging and the need for frequent flushing of the evaporating surface. The use of data on solar radiation for the most and least sunny months (April and November, respectively) shows a nonlinear drop (by 46–47%) in productivity for water, which is explained by both nonlinearity of the temperature dependence of water vapor pressure and a nonlinear relationship between the solar collector efficiency and radiation intensity and ambient temperature. Varying the temperature of the cold circuit shows that using a lower temperature increases the water productivity by 5–15%, while keeping the water recovery rate constant.

This work is devoted to the analysis of the relationship between the omniphobic properties of SLIPS coatings based on polymer matrices doped with lubricant and the swelling degree of such organogels. The one-stage method for the creation of matrices based on poly (perfluoroalkyl methacrylates) impregnated with fluori-nated oils with different lubricant content in supercritical (SC) CO 2 medium is proposed. The dependence of the dynamic contact angle hysteresis and the sliding angle on the organogel swelling degree has been studied for water and saturated hydrocarbons droplets. Thermogravimetric analysis and ellipsometry were used to measure the lubricant content in the matrices.

Lithium-rich geothermal waters are considered as an alternative source, and further concentration of lithium is required for its effective recovery. In this work, we have simulated a three-stage lithium recovery process including the brine softening by precipitation Ca2+/Mg2+ cations with sodium carbonate (calculated in PHREEQC), followed by an integrated system consisting of membrane distillation unit (water evaporation), crystallizer (NaCl precipitation), and membrane extraction (Li+ recovery), which was simulated in Simulink/MATLAB. It was shown that the deterioration of membrane performance in time due to scaling/fouling plays a critical role in the performance of the system resulting in the dramatic increase of the replaced membrane modules by a factor of 5. Low cost membranes are required. The process simulation based on the experimental and literature data on the high salinity solutions with the membrane distillation revealed that the specific productivity can be achieved in the range of 9.9–880 g (Li+) per square meter of membranes in the module used before its replacement. The increase of energy efficiency is needed. The mass-flow-rate of saline solution circulated to the crystallizer was set at its almost minimum value as 6.5 kg/min to enable its successful operation at the given parameters of the membrane distillation unit. In other words, the operation of the integrated system having 140 kg of saline solution in the loop and a membrane module of 2.5 m2 for concentration of lithium presence from 0.11 up to 2.3 g/kg would be associated with the circulation of about of 259 tons of saline solution per month between the distillation unit (60 °C) and the crystallizer (15 °C) to yield of up to 1.4 kg of lithium ions. The comprehensive summary and discussion are presented in the conclusions section.

The influence of hyper-crosslinked polystyrene (HCPS) MacronetTM MN200 on the gas transport properties and aging of the highly permeable glassy polymer poly(1-trimethylsilyl-1-propyne) (PTMSP) was studied and analyzed in detail. The gas transport characteristics of dense PTMSP membranes containing 0–10.0 wt % HCPS were studied. It was shown that the introduction of a small amount of HCPS into the PTMSP matrix led to a 50–60% increase of the permeability coefficients of the material for light gases (N2, O2, CO2) and slowed down the deterioration of polymer transport properties over time. The lowest reduction in gas permeability coefficients (50–57%) was found for PTMSP containing HCPS 5.0 wt % after annealing at 100 °C for 300 h. It was found that HCPS sorbed residues of tantalum-based polymerization catalyst from PTMSP. In order to investigate the influence of catalysts on transport and physical properties of PTMSP, we purified the latter from the polymerization catalyst by addition of 5 wt % HCPS into polymer/chloroform solution. It was shown that sorption on HCPS allowed for almost complete removal of tantalum compounds from PTMSP. The membrane made of PTMSP purified by HCPS demonstrated more stable transport characteristics compared to the membrane made of the initial polymer. HCPS has a complex effect on the aging process of PTMSP. The introduction of HCPS into the polymer matrix not only slowed down the physical aging of PTMSP, but also reduced chemical aging due to removal of active reagents.

The ternary system water–ethylene glycol–dimethyl sulfoxide (H2O–EG–DMSO) was investigated by differential scanning calorimetry in the temperature range of 188–298 K. In the concentration range from ∼10 to ∼50 mol% DMSO, crystallization or glass formation are not observed when the temperature is lowered to 188 K. Significant supercooling of the solution in this composition range is explained by the existence of spatial networks of H2O and EG.

This article describes a new technique for the preparation of hollow fiber (HF) membrane samples using an automatic manipulator unit. The manipulator uses a syringe needle to form a HF of a given geometry. The needle in automatic mode is sequentially immersed, first into the polymer solution and then into the coagulation bath. The possibility of using a manipulator to obtain HF samples was studied on the known polysulfone (PSf)/N-methylpyrrolidone (NMP)/pore-forming additive system. A series of HF membrane samples were made within 29 h from twelve 1 mL PSf casting solutions. This was 15 times faster than obtaining samples of HF membranes at the multifunctional research laboratory facility. From the point of view of the consumption of the components of the casting solution, the use of the manipulator was 30 times more economical, and the consumption of water for precipitation and washing was 8000 times less. The developed method made it possible to study samples of HF by scanning electron microscopy (SEM), ultrafiltration, and evaluate its mechanical properties without spinning the membranes. Using the new technique, the optimal composition of the casting solution for the wet spinning of HF PSf membranes was selected during two weeks. Thus, the manipulator makes it possible to significantly reduce the time of the new membrane preparation, reduce the volume of used polymer, and thus makes it promising to study expensive or new membrane materials.

The study addresses the relationship between the omniphobic properties of coatings based on polymer matrices doped with liquid lubricants (Slippery Liquid-Infused Porous Surfaces, SLIPS) and the degree of swelling of the matrices in the lubricant. A method for fabrication of matrices based on poly(perfluoroalkyl methacrylates) impregnated with fluorinated oils with different lubricant contents by one-stage synthesis in supercritical (SC) CO2 is proposed. The dependence of the contact angle hysteresis and the sliding angle on the degree of swelling was studied for water and saturated hydrocarbon droplets. The lubricant content in the matrices was determined by thermogravimetric analysis and ellipsometry.

A novel concept of film distillation equipped with the membrane condenser (FD-MC) was proposed and implemented for the concentration of brine salt solutions. In this thermo-gradient method, the water was evaporated from the thin liquid film flowing alongside the hot surface, and then directly condensed on the cold surface of the porous membrane placed at the distance of few millimeters from the feed. The change of the membrane positioning from the hot feed solution to the cold water stream (coolant circuit) enables to overcome the common challenges of the membrane distillation process like long-term stability towards pores wetting, membrane scaling, and latent heat loss. Comparing with the air gap membrane distillation with membrane condenser (AGMD-MC), FD-MC demonstrated higher water flux (14.7 kg/m(2).h) and stable performance during the concentration of NaCl solution from 50 up to 230 g/kg (microcrystal formation was noticed) even in the presence of organic pollutants (kerosene or surfactants). A mathematical model of heat and mass transfer in FD-MC process was proposed and successfully verified. With the respect to the temperature of hot (40-100 degrees C) and cold (10-60 degrees C) circuits, the energy consumption and thermal efficiency of FD-MC process were in the range of 2.7-3.2 MJ/kg and up to 97%, respectively.

For the first time, the effect of the side-chain in polyalkylmethylsiloxane towards pervaporative removal of methyl tert-butyl ether (MTBE) from water was studied. The noticeable enhancement of separation factor during the pervaporation of 1 wt.% MTBE solution in water through the dense film (40–50 µm) can be achieved by substitution of a methyl group (separation factor 111) for heptyl (161), octyl (169) or decyl (180) one in polyalkylmethylsiloxane. Composite membrane with the selective layer (~8 µm) made of polydecylmethylsiloxane (M10) on top of microfiltration support (MFFK membrane) demonstrated MTBE/water separation factor of 310, which was 72% greater than for the dense film (180). A high separation factor together with an overall flux of 0.82 kg·m−2·h−1 allowed this M10/MFFK composite membrane to outperform the commercial composite membranes. The analysis of the concentration polarization modulus and the boundary layer thickness revealed that the feed flow velocity should be gradually increased from 5 cm·s−1 for an initial solution (1 wt.% of MTBE in water) to 13 cm·s−1 for a depleted solution (0.2 wt.% of MTBE in water) to overcome the concentration polarization phenomena in case of composite membrane M10/MFFK (Texp = 50 °C).

A scheme of a membrane distillation unit with the possibility of using solar energy collectors has been proposed for treatment of water–salt solutions. This scheme has been tested in the Simulink (MATLAB) simulation environment using a seawater desalination process as a model system. Based on solar radiation data received in Vietnam, a distillation process has been simulated using a solar collector and an electric heater. Experimental approbation of the model has been carried out by the desalination of a NaCl solution by membrane distillation with a porous condenser. The calculated productivity of the modeled system agrees with the obtained experimental data. Simulation showed the possibility of reducing energy consumption by 61% in the process of desalination of an aqueous solution of NaCl using low-grade heat.

The mitigation of the physical aging of thin-film composite (TFC) poly[1-trimethylsilyl-1-propyne] (PTMSP) membranes was studied via the simultaneous application of a polymer-selective layer crosslinking and mixed-matrix membrane approach. For the first time, a recently developed highly porous activated carbon material (infrared (IR) pyrolyzed poly[acrylonitrile] (PAN) or IR-PAN-a) was investigated as an additive to a PTMSP-selective layer for the reduction of aging in TFC membranes. The total electric energy spent on the IR irradiation treatment of IR-PAN-a particles was twice lower than conventional heating. The flat-sheet porous microfiltration membrane MFFK-1 was used as a support, and the crosslinked PTMSP/PEI loaded with a porous filler was applied as a selective layer (0.8–1.8 µm thick) to the TFC membranes. The initial IR-PAN-a sample was additionally milled to obtain a milled IR-PAN-aM sample with a monomodal particle size distribution of 500–800 nm. It was shown that IR-PAN-a, as a filler material with a high surface area and pore volume (2450 m2/g and 1.06 cm3/g, respectively) and a well-developed sponge-like structure, leads to the increase of the N2, O2, and CO2 permeance of PTMSP-based hybrid membrane material and the decrease of the aging of PTMSP. The simultaneous effect of crosslinking and the addition of a highly porous filler essentially improved the aging behavior of PTMSP-based TFC membranes. The monomodal and narrow particle size distribution of highly porous activated IR-pyrolyzed PAN is a key factor for the production of TFC membranes with reduced aging. The highest stability was achieved by the addition of a milled IR-PAN-aM sample (10 wt%). TFC membrane permeance was 6300 GPU (30% of initial permeance) after 11,000 h of aging at ambient laboratory conditions.

DSC and DTA were used to construct the phase diagram of the water–monoethanolamine (MEA) system in a temperature range of 133–313 K. The phase diagram is characterized by the supercooling of a liquid phase and devitrification at ∼150 K. MEA·2H2O (congruently melted at 238 K), MEA·H2O (incongruently melted at 248 K), and limited solid solutions of MEA in H2O were detected.

The monoethanolamine–dioxane system was examined by the DSC performed at various cooling/heating rates in the temperature range from −140 to +25 °C. Rapid cooling revealed that the system undergoes a glass transition at about −120 °C, while in the case of slow cooling, the crystallization of two dioxane phases was observed at +4 and −20 °C. The phase diagram of eutectic type with strong supercooling of the liquid phase was obtained for this system.