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A Commemorative Issue in Honor of Docent Constantin Luca: pH in Membrane Processes

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A special issue of Membranes (ISSN 2077-0375). This special issue belongs to the section "Membrane Processing and Engineering".

Deadline for manuscript submissions: closed (30 September 2022) | Viewed by 18646

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Prof. Dr. Gheorghe Nechifor

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Analytical Chemistry and Environmental Engineering Department, University Politehnica of Bucharest, Bucharest 011061, Romania
Interests: environmental quality control; environmental engineering; environmental chemistry; membrane and membrane processes; decontaminations techniques
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Dear Colleagues,

Ten years ago, on a sad December evening, we said goodbye to Professor Doctor Docent Constantin LUCA, director of the Department of Analytical Chemistry and Instrumental Analysis at the University Politehnica of Bucharest.

Professor Dr. Doc. Constantin Luca was a graduate in 1954 of the Faculty of Chemistry of the University of Bucharest with a specialty in Physical Chemistry, who then pursued his passion for research and education within a university, either in Romania or in France.

On his didactic and scientific activity, for over 50 years he achieved over 270 specialist articles, 17 book titles, and 10 patents which cover much expertise such as: analytical chemistry, solutions chemistry, membranes and membrane processes, supramolecular chemistry, high performance materials, pH of aqueous solutions, environmental protection, electrochemical sensors, chemical speciation in aqueous media and equilibrium diagrams.

However, Professor Constantin Luca appreciated much more the training of 75 doctors in chemistry science, whom he always considered his children!

Two of his passions have had the most interesting and appreciated results: solution pH and liquid membranes and membrane processes.

In fact, his book "pH and its Applications" was so appreciated that the Professor was dubbed "The Father of pH".

In the memory of Professor Constantin Luca, we propose to the researchers in the field of membranes a subject that we consider he would have liked very much: the implications of pH in membrane processes.

The great impact of pH upon membrane science and technology continues to give an excellent argument to amplify the theoretical and experimental studies. Membranes and membrane processes represent the main domain in which pH has been capitalized for their potential. Chemical and photochemical oxidation resistance; high selectivity; sensitivity to physical, chemical, and biological parameters; high flow at low pressures; and longer lifetime of the membranes are the characteristics which can be much influenced by pH evolution.

This Special Issue aims to cover a broad range of subjects, from pH implication to membrane preparation, membrane processes, and technologies.

We welcome the submission of full papers, communications, and reviews.

Potential topics include, but are not limited to:

Membrane preparation
Membrane processes based on pH driving force
pH implication on membrane reactors systems
Selective separation
pH sensing membranes
pH control in membrane processes
pH as operating parameter
Membrane degradation
pH on membrane modification on

Prof. Dr. Gheorghe Nechifor
Guest Editor

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Keywords

pH sensitive membrane
selective membranes
membrane nanospecies
nanocarriers
nanoseparation
membrane reactors
selective separations
pH membrane sensors
pH membrane applications

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Published Papers (8 papers)

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Research

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27 pages, 15992 KiB

Open AccessArticle

Chitosan–sEPDM and Melatonin–Chitosan–sEPDM Composite Membranes for Melatonin Transport and Release

by Florentina Mihaela Păncescu, Abbas Abdul Kadhim Klaif Rikabi, Ovidiu Cristian Oprea, Alexandra Raluca Grosu, Aurelia Cristina Nechifor, Vlad-Alexandru Grosu, Szidonia-Katalin Tanczos, Florina Dumitru, Gheorghe Nechifor and Simona Gabriela Bungău

Membranes 2023, 13(3), 282; https://doi.org/10.3390/membranes13030282 - 27 Feb 2023

Cited by 6 | Viewed by 1810

Abstract

Melatonin is the hormone that focuses the attention of the researchers in the medical, pharmaceutical, materials, and membranes fields due to its multiple biomedical implications. The variety of techniques and methods for the controlled release of melatonin is linked to the multitude of applications, among which sports medicine occupies a special place. This paper presents the preparation and characterization of composite membranes based on chitosan (Chi) and sulfonated ethylene-propylene-diene terpolymer (sEPDM). The membranes were obtained by controlled vacuum evaporation from an 8% sEPDM solution in toluene (w/w), in which chitosan was dispersed in an ultrasonic field (sEPDM:Chi = 1:1, w/w). For the comparative evaluation of the membranes’ performances, a melatonin-chitosan-sulfonated ethylene-propylene-diene terpolymer (Mel:Chi:sEPDM = 0.5:0.5:1.0, w/w/w) test membrane was made. The prepared membranes were morphologically and structurally characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), energy-dispersive spectroscopy analysis (EDAX), thermal analysis (TG, DSC), thermal analysis coupled with chromatography and infrared analysis, and contact angle measurements, but also from the point of view of performance in the process of transport and release of melatonin in dedicated environments (aqueous solutions with controlled pH and salinity). The prepared membranes can release melatonin in amounts between 0.4 mg/cm²·per day (sEPDM), 1.6 mg/ cm²·per day (Chi/sEPDM), and 1.25 mg/cm²·per day (Mel/Chi/SEPDM). Full article

(This article belongs to the Special Issue A Commemorative Issue in Honor of Docent Constantin Luca: pH in Membrane Processes)

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17 pages, 6994 KiB

Open AccessFeature PaperEditor’s ChoiceArticle

Obtaining and Characterizing the Osmium Nanoparticles/n–Decanol Bulk Membrane Used for the p–Nitrophenol Reduction and Separation System

by Aurelia Cristina Nechifor, Alexandru Goran, Szidonia-Katalin Tanczos, Florentina Mihaela Păncescu, Ovidiu-Cristian Oprea, Alexandra Raluca Grosu, Cristian Matei, Vlad-Alexandru Grosu, Bogdan Ștefan Vasile and Paul Constantin Albu

Membranes 2022, 12(10), 1024; https://doi.org/10.3390/membranes12101024 - 21 Oct 2022

Cited by 7 | Viewed by 2006

Abstract

Liquid membranes based on nanoparticles follow a continuous development, both from obtaining methods and characterization of techniques points of view. Lately, osmium nanoparticles have been deposited either on flat membranes, with the aim of initiating some reaction processes, or on hollow fiber membranes, with the aim of increasing the contact surface with the phases of the membrane system. This paper presents the obtainment and characterization of a liquid membrane based on osmium nanoparticles (Os–NP) dispersed in ndecanol (nDol) for the realization of a membrane system with a large contact surface between the phases, but without using a liquid membrane support. The dispersion of osmium nanoparticles in n-decanol is carried out by the method of reducing osmium tetroxide with 1–undecenoic acid (UDA). The resulting membrane was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive spectroscopy analysis (EDAX), thermoanalysis (TG, DSC), Fourier transform infra-red (FTIR) spectroscopy and dynamic light scattering (DLS). In order to increase the mass transfer surface, a design for the membrane system was realized with the dispersion of the membrane through the receiving phase and the dispersion of the source phase through the membrane (DBLM-dispersion bulk liquid membrane). The process performance was tested for the reduction of p–nitrophenol (pNP) from the source phase, using sodium tetra-borohydride (NaBH₄), to p–aminophenol (pAP), which was transported and collected in the receiving phase. The obtained results show that membranes based on the dispersion of osmium nanoparticles in n–decanol can be used with an efficiency of over 90% for the reduction of p–nitrophenol and the separation of p–aminophenol. Full article

(This article belongs to the Special Issue A Commemorative Issue in Honor of Docent Constantin Luca: pH in Membrane Processes)

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26 pages, 8931 KiB

Open AccessArticle

pH and pCl Operational Parameters in Some Metallic Ions Separation with Composite Chitosan/Sulfonated Polyether Ether Ketone/Polypropylene Hollow Fibers Membranes

by Anca Maria Cimbru, Abbas Abdul Kadhim Klaif Rikabi, Ovidiu Oprea, Alexandra Raluca Grosu, Szidonia-Katalin Tanczos, Maria Claudia Simonescu, Dumitru Pașcu, Vlad-Alexandru Grosu, Florina Dumitru and Gheorghe Nechifor

Membranes 2022, 12(9), 833; https://doi.org/10.3390/membranes12090833 - 26 Aug 2022

Cited by 7 | Viewed by 1902

Abstract

The development of new composite membranes is required to separate chemical species from aggressive environments without using corrective reagents. One such case is represented by the high hydrochloric acid mixture (very low pH and pCl) that contains mixed metal ions, or that of copper, cadmium, zinc and lead ions in a binary mixture (Cu–Zn and Cd–Pb) or quaternary mixture. This paper presents the obtaining of a composite membrane chitosan (Chi)–sulfonated poly (ether ether ketone) (sPEEK)–polypropylene hollow fiber (Chi/sPEEK/PPHF) and its use in the separation of binary or quaternary mixtures of copper, cadmium, zinc, and lead ions by nanofiltration and pertraction. The obtained membranes were morphologically and structurally characterized using scanning electron microscopy (SEM), high resolution SEM (HR–SEM), energy dispersive spectroscopy analysis (EDAX), Fourier Transform InfraRed (FTIR) spectroscopy, thermogravimetric analysis, and differential scanning calorimetry (TGA-DSC), but also used in preliminary separation tests. Using the ion solutions in hydrochloric acid 3 mol/L, the separation of copper and zinc or cadmium and lead ions from binary mixtures was performed. The pertraction results were superior to those obtained by nanofiltration, both in terms of extraction efficiency and because at pertraction, the separate cation was simultaneously concentrated by an order of magnitude. The mixture of the four cations was separated by nanofiltration (at 5 bars, using a membrane of a 1 m² active area) by varying two operational parameters: pH and pCl. Cation retention could reach 95% when adequate values of operational parameters were selected. The paper makes some recommendations for the use of composite membranes, chitosan (Chi)–sulfonated poly (ether ether ketone) (sPEEK)–polypropylene hollow fiber (Chi/sPEEK/PPHF), so as to obtain the maximum possible retention of the target cation. Full article

(This article belongs to the Special Issue A Commemorative Issue in Honor of Docent Constantin Luca: pH in Membrane Processes)

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14 pages, 5830 KiB

Open AccessArticle

New Hybrid Nanofiltration Membranes with Enhanced Flux and Separation Performances Based on Polyphenylene Ether-Ether-Sulfone/Polyacrylonitrile/SBA-15

by Gabriela Paun, Elena Neagu, Viorica Parvulescu, Mihai Anastasescu, Simona Petrescu, Camelia Albu, Gheorghe Nechifor and Gabriel Lucian Radu

Membranes 2022, 12(7), 689; https://doi.org/10.3390/membranes12070689 - 4 Jul 2022

Cited by 7 | Viewed by 2159

Abstract

This study presents the preparation of hybrid nanofiltration membranes based on poly(1,4-phenylene ether ether sulfone), polyacrylonitrile, poly(vinyl pyrrolidone), and SBA-15 mesoporous silica. Laser treatment of polymeric solutions to enhance the hydrophilicity and performance of membranes was investigated. The membranes’ structure was characterized using scanning electron (SEM) and atomic force (AFM) microscopy and contact angle measurements. The addition of PAN in the casting solution produced significant changes in the membrane structure, from finger-like porous structures to sponge-like porous structures. Increased PAN concentration in the membrane composition enhanced the hydrophilicity of the membrane surface, which also accounted for the improvement in the antifouling capabilities. The permeation of apple pomace extract and the content of polyphenols and flavonoids were used to evaluate the efficacy of the hybrid membranes created. The results showed that the hybrid nanofiltration membranes based on PPEES/PAN/PVP/SBA-15: 15/5/1/1 and 17/3/1/1 exposed to laser for 5 min present a higher rejection coefficient to total polyphenols (78.6 ± 0.7% and 97.8 ± 0.9%, respectively) and flavonoids (28.7 ± 0.2% and 50.3 ± 0.4%, respectively) and are substantially better than a commercial membrane with MWCO 1000 Da or PPEES-PVP-based membrane. Full article

(This article belongs to the Special Issue A Commemorative Issue in Honor of Docent Constantin Luca: pH in Membrane Processes)

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18 pages, 6237 KiB

Open AccessArticle

Simultaneous Release of Silver Ions and 10–Undecenoic Acid from Silver Iron–Oxide Nanoparticles Impregnated Membranes

by Gheorghe Nechifor, Alexandra Raluca Grosu, Andreea Ferencz (Dinu), Szidonia-Katalin Tanczos, Alexandru Goran, Vlad-Alexandru Grosu, Simona Gabriela Bungău, Florentina Mihaela Păncescu, Paul Constantin Albu and Aurelia Cristina Nechifor

Membranes 2022, 12(6), 557; https://doi.org/10.3390/membranes12060557 - 27 May 2022

Cited by 8 | Viewed by 1810

Abstract

The bio-medical benefits of silver ions and 10–undecenoic acid in various chemical-pharmaceutical preparations are indisputable, thus justifying numerous research studies on delayed and/or controlled release. This paper presents the effect of the polymer matrix in the simultaneous release of silver ions and 10–undecenoic acid in an aqueous medium of controlled pH and ionic strength. The study took into consideration polymeric matrices consisting of cellulose acetate (CA) and polysulfone (PSf), which were impregnated with oxide nanoparticles containing silver and 10–undecenoic acid. The studied oxide nanoparticles are nanoparticles of iron and silver oxides obtained by an accessible electrochemical method. The obtained results show that silver can be released, simultaneously with 10–undecenoic acid, from an impregnated polymeric membrane, at concentrations that ensure the biocidal and fungicidal capacity. Concentrations of active substances can be controlled by choosing the polymer matrix or, in some cases, by changing the pH of the target medium. In the studied case, higher concentrations of silver ions are released from the polysulfone matrix, while higher concentrations of 10–undecenoic acid are released from the cellulose acetate matrix. The results of the study show that a correlation can be established between the two released target substances, which is dependent on the solubility of the organic compound in the aqueous medium and the interaction of this compound with the silver ions. The ability of 10–undecenoic acid to interact with the silver ion, both through the carboxyl and alkene groups, contributes to the increase in the content of the silver ions transported in the aqueous medium. Full article

(This article belongs to the Special Issue A Commemorative Issue in Honor of Docent Constantin Luca: pH in Membrane Processes)

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20 pages, 4474 KiB

Open AccessArticle

pH and Design on n–Alkyl Alcohol Bulk Liquid Membranes for Improving Phenol Derivative Transport and Separation

by Paul Constantin Albu, Szidonia-Katalin Tanczos, Andreea Ferencz (Dinu), Andreia Pîrțac, Alexandra Raluca Grosu, Dumitru Pașcu, Vlad-Alexandru Grosu, Constantin Bungău and Aurelia Cristina Nechifor

Membranes 2022, 12(4), 365; https://doi.org/10.3390/membranes12040365 - 26 Mar 2022

Cited by 4 | Viewed by 2286

Abstract

Regardless of the type of liquid membrane (LM) (Bulk Liquid Membranes (BLM), Supported Liquid Membranes (SLM) or Emulsion Liquid Membranes (ELM)), transport and separation of chemical species are conditioned by the operational (OP) and constructive design parameters (DP) of the permeation module. In the present study, the pH of the aqueous source phase (SP) and receiving phase (RP) of the proposed membrane system were selected as operational parameters. The mode of contacting the phases was chosen as the convective transport generator. The experiments used BLM-type membranes with spheres in free rotation as film contact elements of the aqueous phases with the membrane. The target chemical species were selected in the range of phenol derivatives (PD), 4–nitrophenol (NP), 2,4–dichlorophenol (DCP) and 2,4–dinitrophenol (DNP), all being substances of technical-economic and environmental interest. Due to their acid character, they allow the evaluation of the influence of pH as a determining operational parameter of transport and separation through a membrane consisting of n–octanol or n–decanol (n–AlcM). The comparative study performed for the transport of 4–nitrophenol (NP) showed that the module based on spheres (Ms) was more performant than the one with phase dispersion under the form of droplets (Md). The sphere material influenced the transport of 4–nitrophenol (NP). The transport module with glass spheres (Gl) was superior to the one using copper spheres (Cu), but especially with the one with steel spheres (St). In all the studied cases, the sphere-based module (Ms) had superior transport results compared to the module with droplets (Md). The extraction efficiency (EE) and the transport of 2,4–dichlorophenol (DCP) and 2,4–dinitrophenol (DNP), studied in the module with glass spheres, showed that the two phenolic derivatives could be separated by adjusting the pH of the source phase. At the acidic pH of the source phase (pH = 2), the two derivatives were extracted with good results (EE > 90%), while for pH values ranging from 4 to 6, they could be separated, with DCP having doubled separation efficiency compared to DNP. At a pH of 8 in the source phase, the extraction efficiency halved for both phenolic compounds. Full article

(This article belongs to the Special Issue A Commemorative Issue in Honor of Docent Constantin Luca: pH in Membrane Processes)

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27 pages, 5154 KiB

Open AccessArticle

Considerations on the Controlled Delivery of Bioactive Compounds through Hyaluronic Acid Membrane

by Eugenia Eftimie Totu, Daniela Mănuc, Tiberiu Totu, Corina Marilena Cristache, Roxana-Mădălina Buga, Fatih Erci, Camelia Cristea and Ibrahim Isildak

Membranes 2022, 12(3), 303; https://doi.org/10.3390/membranes12030303 - 8 Mar 2022

Cited by 1 | Viewed by 2879

Abstract

(1) Background: The standard treatment for periodontal disease, a chronic inflammatory state caused by the interaction between biofilms generated by organized oral bacteria and the local host defense response, consists of calculus and biofilm removal through mechanical debridement, associated with antimicrobial therapy that could be delivered either systemically or locally. The present study aimed to determine the effectiveness of a hyaluronic acid membrane matrix as a carrier for the controlled release of the active compounds of a formulation proposed as a topical treatment for periodontal disease, and the influence of pH on the complex system’s stability. (2) Methods: The obtained hyaluronic acid (HA) hydrogel membrane with dispersed melatonin (MEL), metronidazole (MZ), and tetracycline (T) was completely characterized through FTIR, XRD, thermal analysis, UV-Vis and fluorescence spectroscopy, fluorescence microscopy, zeta potential and dielectric analysis. The MTT viability test was applied to check the cytotoxicity of the obtained membranes, while the microbiological assessment was performed against strains of Staphylococcus spp. and Streptococcus spp. The spectrophotometric investigations allowed to follow up the release profile from the HA matrix for MEL, MZ, and T present in the topical treatment considered. We studied the behavior of the active compounds against the pH of the generated environment, and the release profile of the bioactive formulation based on the specific comportment towards pH variation. The controlled delivery of the bioactive compounds using HA as a supportive matrix was modeled applying Korsmeyer–Peppas, Higuchi, first-order kinetic models, and a newly proposed pseudo-first-order kinetic model. (3) Results: It was observed that MZ and T were released at higher active concentrations than MEL when the pH was increased from 6.75, specific for patients with periodontitis, to a pH of 7.10, characterizing the healthy patients. Additionally, it was shown that for MZ, there is a burst delivery up to 2.40 × 10⁻⁵ mol/L followed by a release decrease, while for MEL and T a short release plateau was recorded up to a concentration of 1.80 × 10⁻⁵ mol/L for MEL and 0.90 × 10⁻⁵ mol/L for T, followed by a continuous release; (4) Conclusions: The results are encouraging for the usage of the HA membrane matrix as releasing vehicle for the active components of the proposed topical treatment at a physiological pH. Full article

(This article belongs to the Special Issue A Commemorative Issue in Honor of Docent Constantin Luca: pH in Membrane Processes)

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16 pages, 1260 KiB

Open AccessFeature PaperEditor’s ChoiceReview

Prolonging the Life Span of Membrane in Submerged MBR by the Application of Different Anti-Biofouling Techniques

by Noman Sohail, Ramona Riedel, Bogdan Dorneanu and Harvey Arellano-Garcia

Membranes 2023, 13(2), 217; https://doi.org/10.3390/membranes13020217 - 9 Feb 2023

Cited by 5 | Viewed by 2900

Abstract

The membrane bioreactor (MBR) is an efficient technology for the treatment of municipal and industrial wastewater for the last two decades. It is a single stage process with smaller footprints and a higher removal efficiency of organic compounds compared with the conventional activated sludge process. However, the major drawback of the MBR is membrane biofouling which decreases the life span of the membrane and automatically increases the operational cost. This review is exploring different anti-biofouling techniques of the state-of-the-art, i.e., quorum quenching (QQ) and model-based approaches. The former is a relatively recent strategy used to mitigate biofouling. It disrupts the cell-to-cell communication of bacteria responsible for biofouling in the sludge. For example, the two strains of bacteria Rhodococcus sp. BH4 and Pseudomonas putida are very effective in the disruption of quorum sensing (QS). Thus, they are recognized as useful QQ bacteria. Furthermore, the model-based anti-fouling strategies are also very promising in preventing biofouling at very early stages of initialization. Nevertheless, biofouling is an extremely complex phenomenon and the influence of various parameters whether physical or biological on its development is not completely understood. Advancing digital technologies, combined with novel Big Data analytics and optimization techniques offer great opportunities for creating intelligent systems that can effectively address the challenges of MBR biofouling. Full article

(This article belongs to the Special Issue A Commemorative Issue in Honor of Docent Constantin Luca: pH in Membrane Processes)

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