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14 pages, 2298 KiB

Open AccessArticle

Numerical Study of Drift Influence on Diffusion Transport through the Hybrid Membrane

by Monika Krasowska, Anna Strzelewicz, Gabriela Dudek and Michał Cieśla

Membranes 2022, 12(8), 788; https://doi.org/10.3390/membranes12080788 - 17 Aug 2022

Cited by 2 | Viewed by 1165

Sodium alginate membranes filled with iron oxide nanoparticles consist of a mixture of organic and inorganic phases. This design offers the possibility to combine the polymer’s easy processability and superior separation performance. For a better understanding of the mechanisms of mixture separation, we [...] Read more.

Sodium alginate membranes filled with iron oxide nanoparticles consist of a mixture of organic and inorganic phases. This design offers the possibility to combine the polymer’s easy processability and superior separation performance. For a better understanding of the mechanisms of mixture separation, we analyze the diffusion motion of a particle in the hybrid membrane environment. We model structures of two-dimensional heterogenic membranes, which resemble real membrane structures, and then we simulate a random walk on them. We investigate how the additional action of drift changes the motion properties of the diffusing particles through the polymeric membrane filled with inorganic powder. We test the effect of two parameters: the distribution of obstacles (filling) in the membrane and the value of drift on the nature of diffusion. It appears that the synergy between drift, the diffusion, and the membrane structure affect the occurrence of the superdiffusive and subdiffusive character of particle motion as measured by the time-averaged mean square displacement. An important point is the observation that the strong drift supports subdiffusive motion as it increases the chances of particle trapping. Moreover, there exists the optimal value of drift, for which the transport through a membrane speeds up and does not cause trapping. Full article

(This article belongs to the Special Issue State-of-the-Art Membrane Science and Technology in Poland 2021-2022)

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21 pages, 12843 KiB

Open AccessArticle

The Impact of Operational Parameters on Polypropylene Membrane Performance during the Separation of Oily Saline Wastewaters by the Membrane Distillation Process

by Wirginia Tomczak and Marek Gryta

Membranes 2022, 12(4), 351; https://doi.org/10.3390/membranes12040351 - 22 Mar 2022

Cited by 5 | Viewed by 1758

Abstract

In the present study, membrane distillation (MD) was applied for the treatment of oily saline wastewaters produced on ships sailing the Baltic Sea. For comparison purposes, experiments were also carried out with model NaCl solutions, the Baltic Seawater and oil in water emulsions. [...] Read more.

In the present study, membrane distillation (MD) was applied for the treatment of oily saline wastewaters produced on ships sailing the Baltic Sea. For comparison purposes, experiments were also carried out with model NaCl solutions, the Baltic Seawater and oil in water emulsions. The commercial Accurel PP V8/2 membranes (Membrana GmbH, Germany) were used. In order to investigate the impact of the operational parameters on the process performance, the experiments were conducted under various values of the feed flow velocity (from 0.03 to 0.12 m/s) and the feed temperature (from 323 to 343 K). The obtained results highlight the potential of PP membranes application for a stable and reliable long-term treatment of oily wastewater. It was demonstrated that the permeate flux increased significantly with increasing feed temperature. However, the lower temperature ensured the limited scaling phenomenon during the treatment of oily wastewaters. Likewise, increasing the feed flow velocity was beneficial to the increase in the flux. Moreover, it was found that performing a cyclic rinsing of the module with a 3% HCl solution is an effective method to maintain a satisfactory module performance. The present study sheds light on improving the MD for the treatment of oily wastewaters. Full article

(This article belongs to the Special Issue State-of-the-Art Membrane Science and Technology in Poland 2021-2022)

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19 pages, 7336 KiB

Open AccessArticle

Fabrication of Polyamide-6 Membranes—The Effect of Gelation Time towards Their Morphological, Physical and Transport Properties

by Mohammad Ebrahimi, Wojciech Kujawski and Kateryna Fatyeyeva

Membranes 2022, 12(3), 315; https://doi.org/10.3390/membranes12030315 - 10 Mar 2022

Cited by 2 | Viewed by 2588

Abstract

Porous polyamide-6 membranes were fabricated via a non-solvent induced phase inversion method, and the influence of gelation time on the properties of the membranes was investigated. Membrane samples with various gelation times were prepared. The evaluation of the membranes’ properties was carried out [...] Read more.

Porous polyamide-6 membranes were fabricated via a non-solvent induced phase inversion method, and the influence of gelation time on the properties of the membranes was investigated. Membrane samples with various gelation times were prepared. The evaluation of the membranes’ properties was carried out by various analyses and tests, such as scanning electron microscopy, atomic force microscopy, contact angle, wet and dry thickness, mean pore size measurements, porosity, water uptake, mechanical resistance, hydrodynamic water fluxes, membrane hydrodynamic permeability, and retention testing. The scanning electron microscopy images (both surface and cross-section) demonstrated that the increase in gelation time from 0 (M₀) to 10 (M₁₀) min led to the morphological change of membranes from isotropic (M₀) to anisotropic (M₁₀). The wet and dry thickness of the membranes showed a downward tendency with increasing gelation time. The M₀ membrane exhibited the lowest bubble contact angle of 60 ± 4° and the lowest average surface roughness of 124 ± 22 nm. The highest values of mean pore size and porosity were observed for the M₀ sample (0.710 ± 0.06 µm and 72 ± 2%, respectively), whereas the M₁₀ membrane demonstrated the highest tensile strength of 4.1 MPa. The membrane water uptake was diminished from 62 to 39% by increasing the gelation time from 0 to 10 min. The M₀ membrane also showed the highest hydrodynamic water flux among the prepared membranes, equal to 28.6 L m⁻² h⁻¹ (at Δp = 2 bar). Full article

(This article belongs to the Special Issue State-of-the-Art Membrane Science and Technology in Poland 2021-2022)

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22 pages, 7199 KiB

Open AccessArticle

Study of the Electrical Conductivity of Ion-Exchange Resins and Membranes in Equilibrium Solutions of Inorganic Electrolytes

by Oleksandr Petrov, Natalia Iwaszczuk, Irina Bejanidze, Tina Kharebava, Volodymyr Pohrebennyk, Nato Didmanidze and Nunu Nakashidze

Membranes 2022, 12(2), 243; https://doi.org/10.3390/membranes12020243 - 20 Feb 2022

Cited by 1 | Viewed by 2360

Abstract

The study of the electrical conductivity of ion-exchange membranes in equilibrium electrolyte solutions is of great importance for the theory of membrane processes, in particular for practical electrodialysis. The purpose of the work is to determine the electrical conductivity of industrial ion-exchange membranes [...] Read more.

The study of the electrical conductivity of ion-exchange membranes in equilibrium electrolyte solutions is of great importance for the theory of membrane processes, in particular for practical electrodialysis. The purpose of the work is to determine the electrical conductivity of industrial ion-exchange membranes MK-40 and MA-40, as well as their basis—granules of a bulk layer of industrial ion exchangers KU-2-8 and EDE-10p, by differential and modified contact methods in electrolyte solutions and the development of a new methodology that will give the values that are closest to the true ones; determination of the dependence of electrical membrane conductivity depending on the type of counterion and concentration equilibrium solution and granules of a bulk layer of ion exchangers on the volume fraction of a dry ion exchanger with different degrees of compaction. It is shown that the dependence of the electrical conductivity of diaphragms on the electrolyte concentration, according to theoretical ideas, disappears under compression. It has been experimentally established that the difference method gives lower values of electrical conductivity in the region of low concentrations. The data obtained by the contact method are in good agreement with the results obtained for compressed diaphragms. The membrane conductivity decreases with increasing ion size. Full article

(This article belongs to the Special Issue State-of-the-Art Membrane Science and Technology in Poland 2021-2022)

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11 pages, 3292 KiB

Open AccessCommunication

Three-Stage Membrane Treatment of Wastewater from Biodiesel Production-Preliminary Research

by Magdalena Lech, Agnieszka Klimek, Damian Porzybót and Anna Trusek

Membranes 2022, 12(1), 39; https://doi.org/10.3390/membranes12010039 - 28 Dec 2021

Cited by 3 | Viewed by 2003

Abstract

As biodiesel production as renewable fuel increases, so does the amount of wastewater resulting from this technology. Wastewater is generated during the so-called biodiesel washing, i.e., washing out glycerol and methanol with water. The purified biodiesel must meet international standards, such as EN [...] Read more.

As biodiesel production as renewable fuel increases, so does the amount of wastewater resulting from this technology. Wastewater is generated during the so-called biodiesel washing, i.e., washing out glycerol and methanol with water. The purified biodiesel must meet international standards, such as EN 14214 or the American ASTM D6751 standard. To fully say that biodiesel technology is environmentally friendly, the amount of wastewater should be minimized. It is also desirable that the purified water can be recycled to the technology. For this purpose, wastewater pre-treated by flotation, during which mainly oils are removed, was subjected to three-stage membrane separation. For each of the stages, the membrane was selected and characterized in terms of its separation capacity and stream stability. Starting with microfiltration, which was mainly aimed at reducing turbidity, affects the permeate flux in the following steps. Then, ultrafiltration and nanofiltration membranes were selected. These membranes were aimed at reducing the concentration of inorganic and organic substances. Consequently the cascade was composed of: MF-0.45 µm, UF-150 kDa, and NF-characterized by an 80% degree of desalination. The final permeate has a salt concentration of less than 0.15 g/L and can be reused in biodiesel technology. Full article

(This article belongs to the Special Issue State-of-the-Art Membrane Science and Technology in Poland 2021-2022)

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25 pages, 11384 KiB

Open AccessArticle

Membrane Distillation of Saline Water Contaminated with Oil and Surfactants

by Wirginia Tomczak and Marek Gryta

Membranes 2021, 11(12), 988; https://doi.org/10.3390/membranes11120988 - 17 Dec 2021

Cited by 8 | Viewed by 2710

Abstract

Application of the membrane distillation (MD) process for the treatment of high-salinity solutions contaminated with oil and surfactants represents an interesting area of research. Therefore, the aim of this study is to investigate the effect of low-concentration surfactants in oil-contaminated high-salinity solutions on [...] Read more.

Application of the membrane distillation (MD) process for the treatment of high-salinity solutions contaminated with oil and surfactants represents an interesting area of research. Therefore, the aim of this study is to investigate the effect of low-concentration surfactants in oil-contaminated high-salinity solutions on the MD process efficiency. For this purpose, hydrophobic capillary polypropylene (PP) membranes were tested during the long-term MD studies. Baltic Sea water and concentrated NaCl solutions were used as a feed. The feed water was contaminated with oil collected from bilge water and sodium dodecyl sulphate (SDS). It has been demonstrated that PP membranes were non-wetted during the separation of pure NaCl solutions over 960 h of the module exploitation. The presence of oil (100–150 mg/L) in concentrated NaCl solutions caused the adsorption of oil on the membranes surface and a decrease in the permeate flux of 30%. In turn, the presence of SDS (1.5–2.5 mg/L) in the oil-contaminated high-salinity solutions slightly accelerated the phenomenon of membrane wetting. The partial pores’ wetting accelerated the internal scaling and affected degradation of the membrane’s structure. Undoubtedly, the results obtained in the present study may have important implications for understanding the effect of low-concentration SDS on MD process efficiency. Full article

(This article belongs to the Special Issue State-of-the-Art Membrane Science and Technology in Poland 2021-2022)

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20 pages, 5199 KiB

Open AccessEditor’s ChoiceArticle

Upgrading Biogas from Small Agricultural Sources into Biomethane by Membrane Separation

by Aleksandra Janusz-Cygan, Jolanta Jaschik and Marek Tańczyk

Membranes 2021, 11(12), 938; https://doi.org/10.3390/membranes11120938 - 27 Nov 2021

Cited by 7 | Viewed by 2670

Abstract

The agriculture sector in Poland could provide 7.8 billion m³ of biogas per year, but this potential would be from dispersed plants of a low capacity. In the current study, a membrane process was investigated for the upgrading biogas to biomethane that [...] Read more.

The agriculture sector in Poland could provide 7.8 billion m³ of biogas per year, but this potential would be from dispersed plants of a low capacity. In the current study, a membrane process was investigated for the upgrading biogas to biomethane that conforms to the requirements for grid gas in Poland. It was assumed that such a process is based on membranes made from modified polysulfone or polyimide, available in the market in Air Products PRISM PA1020 and UBE UMS-A5 modules, respectively. The case study has served an agricultural biogas plant in southern Poland, which provides the stream of 5 m³ (STP) h⁻¹ of biogas with a composition of CH₄ (52 vol.%), CO₂ (46.3 vol.%), N₂ (1.6 vol.%) and O₂ (0.1 vol.%), after a pretreatment. It was theoretically shown that this is possible to obtain the biomethane stream of at least 96 vol.% of CH₄ purity, with the concentration of the other biogas components below their respective thresholds, as required in Poland for gas fuel “E”, with methane recovery of up to 87.5% and 71.6% for polyimide and polysulfone membranes, respectively. The energetic efficiency of the separation process is comparable for both membrane materials, as expressed by power excess index, which reaches up to 51.3 kW_th kW_el⁻¹ (polyimide) and 40.7 kW_th kW_el⁻¹ (polysulfone). In turn, the membrane productivity was significantly higher in the case of the polyimide membrane (up to 38.3 kW_th m⁻²) than those based on the polysulfone one (up to 3.13 kW_th m⁻²). Full article

(This article belongs to the Special Issue State-of-the-Art Membrane Science and Technology in Poland 2021-2022)

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12 pages, 2318 KiB

Open AccessArticle

Low- and High-Pressure Membrane Separation in the Production of Process Water for Coke Quenching

by Anna Trusek, Maciej Wajsprych and Andrzej Noworyta

Membranes 2021, 11(12), 937; https://doi.org/10.3390/membranes11120937 - 27 Nov 2021

Cited by 1 | Viewed by 1976

Abstract

Although the time for operating mines and coking plants in many countries is coming to an end due to climate change, we must still ensure that the pollution generated by this source of the economy is minimized. Despite the several stages of treatment [...] Read more.

Although the time for operating mines and coking plants in many countries is coming to an end due to climate change, we must still ensure that the pollution generated by this source of the economy is minimized. Despite the several stages of treatment of the coke-oven effluent, completed with nitrification and denitrification processes preceding final sedimentation, the stream obtained does not meet the requirements of water for coke quenching. That is why the stream after biodegradation and sedimentation was treated on membrane units to ensure water reusing in the coking plant. As the subjected stream contained both solid and dissolved pollutants, a two-stage system was proposed: low- and high-pressure membrane filtration. Industrial modules were tested on pilot units operating under industrial plant conditions. In the case of the ultrafiltration process, all the tested ultrafiltration modules fulfilled the primary task. All of them separated almost completely the turbidities present in the stream, which would have disturbed the operation of the high-pressure plant. Considering the decrease in permeate flux and the possibility of cleaning, a PCI membrane made of PVDF tubes with a diameter of 12.5 mm and pore size of 20 μm was selected. Regarding the high-pressure membrane filtration, the reverse osmosis membrane was significantly better in the removal efficiency of both organic and inorganic dissolved substances. An operating pressure of 3 MPa was chosen for the system. Hence, membrane processes, which are not used as stand-alone treatment units for coke-oven effluents, function well as a final treatment stage. Full article

(This article belongs to the Special Issue State-of-the-Art Membrane Science and Technology in Poland 2021-2022)

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10 pages, 4277 KiB

Open AccessReview

Membrane-Based Solutions for the Polish Coal Mining Industry

by Krzysztof Mitko and Marian Turek

Membranes 2021, 11(8), 638; https://doi.org/10.3390/membranes11080638 - 18 Aug 2021

Cited by 7 | Viewed by 2667

Abstract

Poland still relies largely on coal for energy generation, which creates environmental problems connected to the mining process, particularly the issue of saline waste water discharge. Membrane-based zero liquid discharge systems can be employed to recover important resources from coal mine waste waters, [...] Read more.

Poland still relies largely on coal for energy generation, which creates environmental problems connected to the mining process, particularly the issue of saline waste water discharge. Membrane-based zero liquid discharge systems can be employed to recover important resources from coal mine waste waters, such as demineralized water, salt, magnesium hydroxide, and gypsum. In this paper, we present a historical overview of proposed membrane-based solutions for the Polish coal mining industry and discuss possible further areas of research. Full article

(This article belongs to the Special Issue State-of-the-Art Membrane Science and Technology in Poland 2021-2022)

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