Special Issue "Membranes for Environmental Applications"

A special issue of Membranes (ISSN 2077-0375). This special issue belongs to the section "Membrane Applications in Water Treatment".

Deadline for manuscript submissions: closed (31 October 2015)

Special Issue Editors

Guest Editor
Dr. Alberto Figoli

Institute on Membrane Technology (CNR-ITM), 87036 (Rende), Italy
Website | E-Mail
Interests: polymeric membranes; hollow-fibers; membrane preparation; membrane characterization; pervaporation; antifouling coatings; self-cleaning membranes; ultra-micro filtration; sustainable membrane preparation
Guest Editor
Dr. Alexey Volkov

A.V.Topchiev Institute of Petrochemical Synthesis, Russian Academy of Sciences, Leninsky pr., 29, Moscow Russia, 119071, Russia
Website | E-Mail
Interests: polymer science; membrane technology; membrane formation; membrane characterization; membrane gas absorption/desorption (pre- and post-combustion); solvent resistant nanofiltration; organophilic pervaporation; gas sorption; vapor sorption in nanoporous materials; gas-liquid contactors

Special Issue Information

Dear Colleagues,

Membranes are gaining more and more interest in many different fields because of the low-energy consumption, the mild operating conditions, the possibility to be integrated with other membranes and conventional processes, and the easy scale-up. Thanks to these peculiarities, membranes have been already successfully used in environmental applications. In addition to well-established membrane operations, new ones have been developed, allowing the possibility of enlarging the applicative spectrum of membrane units.

This Special Issue will highlight the importance of the membranes in Environmental Applications. It welcomes both original contributions and reviews related to applications using membranes, mainly for wastewater treatment, desalination, drinking water production, water reuse, removal of toxic metals from water, Volatile Organic Compounds removal from aqueous or gas streams, CO2 removal, and production and recovery of high-added value products from wastewater.

Dr. Alberto Figoli
Dr. Alexey Volkov
Guest Editors

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All papers will be peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Membranes is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1000 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.


Keywords

  • membranes
  • environmental applications
  • water treatment
  • wastewater treatment
  • toxic compounds removal
  • desalination
  • CO2 removal
  • Volatile Organic Compounds

Published Papers (9 papers)

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Research

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Open AccessArticle Clarification of Orange Press Liquors by PVDF Hollow Fiber Membranes
Received: 7 December 2015 / Revised: 9 January 2016 / Accepted: 13 January 2016 / Published: 20 January 2016
Cited by 7 | PDF Full-text (1896 KB) | HTML Full-text | XML Full-text
Abstract
Press liquors are typical by-products of the citrus juice processing characterized by a high content of organic compounds and associated problems of environmental impact, which imply high treatment costs. However, these wastes contain a great number of health promoting substances, including fibers, carotenoids [...] Read more.
Press liquors are typical by-products of the citrus juice processing characterized by a high content of organic compounds and associated problems of environmental impact, which imply high treatment costs. However, these wastes contain a great number of health promoting substances, including fibers, carotenoids and phenolic compounds (mainly flavonoids), whose recovery against waste-destruction technologies is very attractive for new business opportunities. In this work, the clarification of orange press liquor by using microfiltration (MF) membranes is studied as a preliminary step to obtain a permeate stream enriched in antioxidant compounds which can be further processed to produce extracts of nutraceutical and/or pharmaceutical interest. MF poly(vinylidene fluoride) (PVDF) hollow fibers were prepared by the dry/wet spinning technique. A series of fibers was produced from the same polymeric dope, in order to investigate the effect of selected spinning parameters, i.e., bore fluid composition and flowrate, on their properties. The morphology of the produced fibers was analyzed by Scanning Electron Microscopy (SEM). Fibers were further characterized for their mechanical properties, porosity, bubble point, pore size distribution and pure water permeability (PWP). Some of the produced fibers exhibited high permeability (pure water permeability ~530 L/m2·h·bar), coupled to good mechanical resistance and pore size in the range of MF membranes. These fibers were selected and used for the clarification of press liquor from orange peel processing. In optimized operating conditions, the selected fibers produced steady-state fluxes of about 41 L/m2·h with rejections towards polyphenols and total antioxidant activity of 4.1% and 1.4%, respectively. Full article
(This article belongs to the Special Issue Membranes for Environmental Applications)
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Open AccessArticle Treatment of the Bleaching Effluent from Sulfite Pulp Production by Ceramic Membrane Filtration
Received: 31 October 2015 / Revised: 24 December 2015 / Accepted: 30 December 2015 / Published: 31 December 2015
Cited by 7 | PDF Full-text (1376 KB) | HTML Full-text | XML Full-text
Abstract
Pulp and paper waste water is one of the major sources of industrial water pollution. This study tested the suitability of ceramic tubular membrane technology as an alternative to conventional waste water treatment in the pulp and paper industry. In this context, in [...] Read more.
Pulp and paper waste water is one of the major sources of industrial water pollution. This study tested the suitability of ceramic tubular membrane technology as an alternative to conventional waste water treatment in the pulp and paper industry. In this context, in series batch and semi-batch membrane processes comprising microfiltration, ultrafiltration and nanofiltration, ceramic membranes were developed to reduce the chemical oxygen demand (COD) and remove residual lignin from the effluent flow during sulfite pulp production. A comparison of the ceramic membranes in terms of separation efficiency and performance revealed that the two-stage process configuration with microfiltration followed by ultrafiltration was most suitable for the efficient treatment of the alkaline bleaching effluent tested herein, reducing the COD concentration and residual lignin levels by more than 35% and 70%, respectively. Full article
(This article belongs to the Special Issue Membranes for Environmental Applications)
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Open AccessArticle YSZ-Reinforced Alumina Multi-Channel Capillary Membranes for Micro-Filtration
Received: 2 November 2015 / Revised: 23 December 2015 / Accepted: 25 December 2015 / Published: 30 December 2015
Cited by 3 | PDF Full-text (1358 KB) | HTML Full-text | XML Full-text
Abstract
The combined phase-inversion and sintering method not only produces ceramic hollow fibre membranes with much lower fabrication costs than conventional methods, but these membranes can also be designed to have greatly reduced transport resistances for filtration processes. The bottleneck of this technique is [...] Read more.
The combined phase-inversion and sintering method not only produces ceramic hollow fibre membranes with much lower fabrication costs than conventional methods, but these membranes can also be designed to have greatly reduced transport resistances for filtration processes. The bottleneck of this technique is the weak mechanical property of the fibres, due to the small dimensions and the brittle nature of the ceramic materials. In this study, yttrium stabilised zirconia (YSZ) reinforced alumina seven-channel capillary microfiltration membranes were prepared with a pore size of ~230 nm and their mechanical property and permeation characteristics were studied. It is found that the addition of YSZ can effectively enhance the mechanical property of the membrane and also increase pure water permeation flux. The Al2O3-YSZ seven-channel capillary membranes could reach a fracture load of 23.4 N and a bending extension of 0.54 mm when being tested with a 6 cm span, to meet the requirements for most industrial microfiltration applications. Full article
(This article belongs to the Special Issue Membranes for Environmental Applications)
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Open AccessArticle The Effect of Microporous Polymeric Support Modification on Surface and Gas Transport Properties of Supported Ionic Liquid Membranes
Received: 30 October 2015 / Revised: 25 December 2015 / Accepted: 25 December 2015 / Published: 30 December 2015
Cited by 14 | PDF Full-text (2222 KB) | HTML Full-text | XML Full-text
Abstract
Microporous polymers based on anionic macroinitiator and toluene 2,4-diisocyanate were used as a support for 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf2N]) immobilization. The polymeric support was modified by using silica particles associated in oligomeric media, and the influence [...] Read more.
Microporous polymers based on anionic macroinitiator and toluene 2,4-diisocyanate were used as a support for 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim][PF6]) and 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([emim][Tf2N]) immobilization. The polymeric support was modified by using silica particles associated in oligomeric media, and the influence of the modifier used on the polymeric structure was studied. The supported ionic liquid membranes (SILMs) were tested for He, N2, NH3, H2S, and CO2 gas separation and ideal selectivities were calculated. The high values of ideal selectivity for ammonia-based systems with permanent gases were observed on polymer matrixes immobilized with [bmim][PF6] and [emim][Tf2N]. The modification of SILMs by nanosize silica particles leads to an increase of NH3 separation relatively to CO2 or H2S. Full article
(This article belongs to the Special Issue Membranes for Environmental Applications)
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Open AccessArticle Crosslinked PEG and PEBAX Membranes for Concurrent Permeation of Water and Carbon Dioxide
Received: 17 November 2015 / Revised: 11 December 2015 / Accepted: 17 December 2015 / Published: 23 December 2015
Cited by 8 | PDF Full-text (708 KB) | HTML Full-text | XML Full-text
Abstract
Membrane technology can be used for both post combustion carbon dioxide capture and acidic gas sweetening and dehydration of natural gas. These processes are especially suited for polymeric membranes with polyether functionality, because of the high affinity of this species for both H [...] Read more.
Membrane technology can be used for both post combustion carbon dioxide capture and acidic gas sweetening and dehydration of natural gas. These processes are especially suited for polymeric membranes with polyether functionality, because of the high affinity of this species for both H2O and CO2. Here, both crosslinked polyethylene glycol diacrylate and a polyether-polyamide block copolymer (PEBAX 2533©) are studied for their ability to separate CO2 from CH4 and N2 under single and mixed gas conditions, for both dry and wet feeds, as well as when 500 ppm H2S is present. The solubility of gases within these polymers is shown to be better correlated with the Lennard Jones well depth than with critical temperature. Under dry mixed gas conditions, CO2 permeability is reduced compared to the single gas measurement because of competitive sorption from CH4 or N2. However, selectivity for CO2 is retained in both polymers. The presence of water in the feed is observed to swell the PEG membrane resulting in a significant increase in CO2 permeability relative to the dry gas scenario. Importantly, the selectivity is again retained under wet feed gas conditions. The presence of H2S is observed to only slightly reduce CO2 permeability through both membranes. Full article
(This article belongs to the Special Issue Membranes for Environmental Applications)
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Open AccessArticle Extraction of Gold(III) from Hydrochloric Acid Solutions with a PVC-based Polymer Inclusion Membrane (PIM) Containing Cyphos® IL 104
Membranes 2015, 5(4), 903-914; https://doi.org/10.3390/membranes5040903
Received: 17 November 2015 / Accepted: 3 December 2015 / Published: 8 December 2015
Cited by 11 | PDF Full-text (248 KB) | HTML Full-text | XML Full-text
Abstract
Abstract: Poly(vinyl chloride) (PVC) based polymer inclusion membranes (PIMs), with different concentrations of Cyphos® IL 104 as the membrane extractant/carrier, were studied for their ability to extract Au(III) from hydrochloric acid solutions. Some of the PIMs also contained one of the following plasticizers [...] Read more.
Abstract: Poly(vinyl chloride) (PVC) based polymer inclusion membranes (PIMs), with different concentrations of Cyphos® IL 104 as the membrane extractant/carrier, were studied for their ability to extract Au(III) from hydrochloric acid solutions. Some of the PIMs also contained one of the following plasticizers or modifiers: 2-nitrophenyloctyl ether, dioctylphthalate, 1-dodecanol, 1-tetradecanol, or tri(2-ethylhexyl) phosphate. The best performance, in terms of extraction rate and amount of Au(III) extracted, was exhibited by a PIM consisting of 25 wt% Cyphos® IL 104, 5 wt% 1-dodecanol, and 70 wt% PVC. An almost complete back-extraction of the Au(III) extracted from this membrane was achieved by using a 0.10 mol L−1 Na2SO3 receiver solution at pH 8. The stoichiometry of the extracted Au(III)/Cyphos® IL 104 adduct was determined as [P]+ [AuCl4] H+ [PO2] where [P]+ and [PO2] represent trihexyl(tetradecyl) phosphonium and bis(2,4,4-trimethylpentyl) phosphinate ions, respectively. Back-extraction of Au(III) is suggested to occur by reduction of Au(III) to Au(I), with the formation of the species [Au(SO3)2]3− in the aqueous receiver solution. Loss of 1-dodecanol from the newly developed PIM to the aqueous solutions in contact with it was observed, which indicated that this membrane was suitable for single use in the efficient recovery of Au(III) from hydrochloric acid solutions of electronic scrap or recycled jewelry. Full article
(This article belongs to the Special Issue Membranes for Environmental Applications)
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Open AccessArticle Application of Membrane Crystallization for Minerals’ Recovery from Produced Water
Membranes 2015, 5(4), 772-792; https://doi.org/10.3390/membranes5040772
Received: 28 October 2015 / Accepted: 17 November 2015 / Published: 24 November 2015
Cited by 15 | PDF Full-text (851 KB) | HTML Full-text | XML Full-text
Abstract
Produced water represents the largest wastewater stream from oil and gas production. Generally, its high salinity level restricts the treatment options. Membrane crystallization (MCr) is an emerging membrane process with the capability to extract simultaneously fresh water and valuable components from various streams. [...] Read more.
Produced water represents the largest wastewater stream from oil and gas production. Generally, its high salinity level restricts the treatment options. Membrane crystallization (MCr) is an emerging membrane process with the capability to extract simultaneously fresh water and valuable components from various streams. In the current study, the potential of MCr for produced water treatment and salt recovery was demonstrated. The experiments were carried out in lab scale and semi-pilot scale. The effect of thermal and hydrodynamic conditions on process performance and crystal characteristics were explored. Energy dispersive X-ray (EDX) and X-ray diffraction (XRD) analyses confirmed that the recovered crystals are sodium chloride with very high purity (>99.9%), also indicated by the cubic structure observed by microscopy and SEM (scanning electron microscopy) analysis. It was demonstrated experimentally that at recovery factor of 37%, 16.4 kg NaCl per cubic meter of produced water can be recovered. Anti-scaling surface morphological features of membranes were also identified. In general, the study provides a new perspective of isolation of valuable constituents from produced water that, otherwise, is considered as a nuisance. Full article
(This article belongs to the Special Issue Membranes for Environmental Applications)
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Open AccessArticle Hollow Fiber Membrane Dehumidification Device for Air Conditioning System
Membranes 2015, 5(4), 722-738; https://doi.org/10.3390/membranes5040722
Received: 24 July 2015 / Accepted: 9 November 2015 / Published: 16 November 2015
Cited by 17 | PDF Full-text (1076 KB) | HTML Full-text | XML Full-text
Abstract
In order to provide a comfortable living and working environment indoors in tropical countries, the outdoor air often needs to be cooled and dehumidified before it enters the rooms. Membrane separation is an emerging technology for air dehumidification and it is based on [...] Read more.
In order to provide a comfortable living and working environment indoors in tropical countries, the outdoor air often needs to be cooled and dehumidified before it enters the rooms. Membrane separation is an emerging technology for air dehumidification and it is based on the solution diffusion mechanism. Water molecules are preferentially permeating through the membranes due to its smaller kinetic diameter and higher condensability than the other gases. Compared to other dehumidification technologies such as direct cooling or desiccation, there is no phase transition involved in membrane dehumidification, neither the contact between the fresh air stream and the desiccants. Hence, membrane dehumidification would not only require less energy consumption but also avoid cross-contamination problems. A pilot scale air dehumidification system is built in this study which comprises nine pieces of one-inch PAN/PDMS hollow fiber membrane modules. A 150 h long-term test shows that the membrane modules has good water vapor transport properties by using a low vacuum force of only 0.78 bar absolute pressure at the lumen side. The water vapor concentration of the feed humid air decreases dramatically from a range of 18–22 g/m3 to a range of 13.5–18.3 g/m3. Most importantly, the total energy saving is up to 26.2% compared with the conventional air conditioning process. Full article
(This article belongs to the Special Issue Membranes for Environmental Applications)
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Review

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Open AccessReview On the Recent Use of Membrane Technology for Olive Mill Wastewater Purification
Membranes 2015, 5(4), 513-531; https://doi.org/10.3390/membranes5040513
Received: 6 August 2015 / Accepted: 24 September 2015 / Published: 28 September 2015
Cited by 14 | PDF Full-text (270 KB) | HTML Full-text | XML Full-text
Abstract
Many reclamation treatments as well as integrated processes for the purification of olive mill wastewaters (OMW) have already been proposed and developed but not led to completely satisfactory results, principally due to complexity or cost-ineffectiveness. The olive oil industry in its current status, [...] Read more.
Many reclamation treatments as well as integrated processes for the purification of olive mill wastewaters (OMW) have already been proposed and developed but not led to completely satisfactory results, principally due to complexity or cost-ineffectiveness. The olive oil industry in its current status, composed of little and dispersed factories, cannot stand such high costs. Moreover, these treatments are not able to abate the high concentration of dissolved inorganic matter present in these highly polluted effluents. In the present work, a review on the actual state of the art concerning the treatment and disposal of OMW by membranes is addressed, comprising microfiltration (MF), ultrafiltration (UF), nanofiltration (NF), and reverse osmosis (RO), as well as membrane bioreactors (MBR) and non-conventional membrane processes such as vacuum distillation (VD), osmotic distillation (OD) and forward osmosis (FO). Membrane processes are becoming extensively used to replace many conventional processes in the purification of water and groundwater as well as in the reclamation of wastewater streams of very diverse sources, such as those generated by agro-industrial activities. Moreover, a brief insight into inhibition and control of fouling by properly-tailored pretreatment processes upstream the membrane operation and the use of the critical and threshold flux theories is provided. Full article
(This article belongs to the Special Issue Membranes for Environmental Applications)
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