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1896 KiB

Open AccessArticle

Clarification of Orange Press Liquors by PVDF Hollow Fiber Membranes

by Silvia Simone, Carmela Conidi, Claudia Ursino, Alfredo Cassano and Alberto Figoli

Membranes 2016, 6(1), 9; https://doi.org/10.3390/membranes6010009 - 20 Jan 2016

Cited by 17 | Viewed by 6060

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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1376 KiB

Open AccessArticle

Treatment of the Bleaching Effluent from Sulfite Pulp Production by Ceramic Membrane Filtration

by Mehrdad Ebrahimi, Nadine Busse, Steffen Kerker, Oliver Schmitz, Markus Hilpert and Peter Czermak

Membranes 2016, 6(1), 7; https://doi.org/10.3390/membranes6010007 - 31 Dec 2015

Cited by 43 | Viewed by 9480

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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1358 KiB

Open AccessArticle

YSZ-Reinforced Alumina Multi-Channel Capillary Membranes for Micro-Filtration

by Bo Wang, Melanie Lee and Kang Li

Membranes 2016, 6(1), 5; https://doi.org/10.3390/membranes6010005 - 30 Dec 2015

Cited by 6 | Viewed by 6118

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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2222 KiB

Open AccessArticle

The Effect of Microporous Polymeric Support Modification on Surface and Gas Transport Properties of Supported Ionic Liquid Membranes

by Alsu A. Akhmetshina, Ilsiya M. Davletbaeva, Ekaterina S. Grebenschikova, Tatyana S. Sazanova, Anton N. Petukhov, Artem A. Atlaskin, Evgeny N. Razov, Ilnaz I. Zaripov, Carla F. Martins, Luísa A. Neves and Ilya V. Vorotyntsev

Membranes 2016, 6(1), 4; https://doi.org/10.3390/membranes6010004 - 30 Dec 2015

Cited by 40 | Viewed by 7134

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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708 KiB

Open AccessArticle

Crosslinked PEG and PEBAX Membranes for Concurrent Permeation of Water and Carbon Dioxide

by Colin A. Scholes, George Q. Chen, Hiep T. Lu and Sandra E. Kentish

Membranes 2016, 6(1), 1; https://doi.org/10.3390/membranes6010001 - 23 Dec 2015

Cited by 20 | Viewed by 6964

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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248 KiB

Open AccessArticle

Extraction of Gold(III) from Hydrochloric Acid Solutions with a PVC-based Polymer Inclusion Membrane (PIM) Containing Cyphos^® IL 104

by Ya Ya Nutchapurida Bonggotgetsakul, Robert W. Cattrall and Spas D. Kolev

Membranes 2015, 5(4), 903-914; https://doi.org/10.3390/membranes5040903 - 08 Dec 2015

Cited by 33 | Viewed by 6046

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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851 KiB

Open AccessArticle

Application of Membrane Crystallization for Minerals’ Recovery from Produced Water

by Aamer Ali, Cejna Anna Quist-Jensen, Francesca Macedonio and Enrico Drioli

Membranes 2015, 5(4), 772-792; https://doi.org/10.3390/membranes5040772 - 24 Nov 2015

Cited by 79 | Viewed by 9124

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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1076 KiB

Open AccessArticle

Hollow Fiber Membrane Dehumidification Device for Air Conditioning System

by Baiwang Zhao, Na Peng, Canzeng Liang, Wai Fen Yong and Tai-Shung Chung

Membranes 2015, 5(4), 722-738; https://doi.org/10.3390/membranes5040722 - 16 Nov 2015

Cited by 57 | Viewed by 12710

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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270 KiB

Open AccessReview

On the Recent Use of Membrane Technology for Olive Mill Wastewater Purification

by Javier Miguel Ochando-Pulido and Antonio Martinez-Ferez

Membranes 2015, 5(4), 513-531; https://doi.org/10.3390/membranes5040513 - 28 Sep 2015

Cited by 35 | Viewed by 6036

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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