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Bio-Based Polyelectrolytes: Development and Applications

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A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Biomacromolecules, Biobased and Biodegradable Polymers".

Deadline for manuscript submissions: closed (10 December 2020) | Viewed by 23226

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Special Issue Editors

Dr. Maria Graça Rasteiro

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Chemical Process Engineering and Forest Products Research Centre (CIEPQPF), Department of Chemical Engineering, University of Coimbra, Rua Sílvio Lima, 3030-790 Coimbra, Portugal
Interests: particle technology, including particle characterization; multiphase processes, including modelling and experimental; rheology of suspensions; tomographic techniques for multiphase flow visualization; aggregation/flocculation of particles; valorization of ligno-cellulosic materials—development of natural polyelectrolytes and lignin-based surfactants; remediation of soils; microplastics identification and removal
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Dr. José Gamelas

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CIEPQPF – Chemical Process Engineering and Forest Products Research Centre, Department of Chemical Engineering, University of Coimbra, Rua Sílvio Lima, 3030-790 Coimbra, Portugal
Interests: cellulose chemistry; nanocellulose production and characterization; cellulose and nanocellulose-based organic–inorganic hybrid materials; bio-based polyelectrolytes from lignocellulosic materials; polyoxometalate compounds for sensor applications; recycling of inorganic waste materials; inverse gas chromatography applied to the characterization of powdered and fibrous materials; surface characterization of materials by X-ray photoelectron spectroscopy

Dr. Luis Alves

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CIEPQPF—Chemical Process Engineering and Forest Products Research Centre, Department of Chemical Engineering, University of Coimbra, Rua Sílvio Lima, 3030-790 Coimbra, Portugal
Interests: cellulose chemistry; cellulose dissolution and regeneration; nanocellulose production and characterization; cellulose and nanocellulose-based organic–inorganic hybrid materials; bio-based polyelectrolytes from lignocellulosic materials; lignin-based materials; rheology; surfactants; polymer–surfactant association; microscopy
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

Polyelectrolytes are polymers which contain constitutional units with ionic or ionizable groups and therefore possess the possibility of acquiring a charge. This gives them important characteristics which favor application in different processes/systems, including water and effluent treatment (flocculation); cosmetics; food; pharmaceutical industry; drug delivery applications; and preparation of composites, among others.

Traditionally, polyelectrolytes are synthetic molecules (polymers) varying in molecular weight, charge, and structure. Most often, the synthesis of these polymers is based on the use of oil-based monomers, which impairs its biodegradability and, sometimes, even raises toxicity issues, especially when considering some of the applications mentioned.

In recent years, natural-based polyelectrolytes, also called bio-polyelectrolytes, have started catching the attention of the research community. The big advantage is that these molecules of different origin are biodegradable, usually nontoxic, and, also very important, they quite often correspond to the valorization of waste materials. Some examples of these bio-polylectrolytes are chitosan-based; cellulose-based; lignin-based; starch-based; alginate-based; and pectin-based polyelectrolytes as well as polyelectrolytes produced by micro-organisms. However, for these bio-polyelectrolytes to be effective, it is quite often necessary to carry out some modification of the natural materials, either to improve its reactivity, solubility or improve its resistance (flexibility) to the medium where they are going to be used (pH, ionic content, temperature).

In this Special Issue, the objective is to bring together new developments in the field of bio-polyelectrolyte (natural-based polyelectrolyte) production, including use of different raw materials, pretreatment of the raw materials, waste valorization, modification procedures, toxicity and biodegradability evaluation, characterization methodologies, assembly of polyelectrolytes, and application in different fields, including industrial application.

Prof. Maria Graça Rasteiro
Dr. José Gamelas
Dr. Luis Alves
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 submissions that pass pre-check are 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. Polymers is an international peer-reviewed open access semimonthly 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 2700 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

bio-based polyelectrolytes
cellulose
lignin
polysaccharides
enzymes
biodegradability
waste valorization
characterization of polyelectrolytes
sustainability
applications of polyelectrolyte systems

Published Papers (7 papers)

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Research

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16 pages, 10577 KiB

Open AccessEditor’s ChoiceArticle

Stabilization of Palygorskite Aqueous Suspensions Using Bio-Based and Synthetic Polyelectrolytes

by Eduardo Ferraz, Luís Alves, Pedro Sanguino, Julio Santarén, Maria G. Rasteiro and José A. F. Gamelas

Polymers 2021, 13(1), 129; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13010129 - 30 Dec 2020

Cited by 8 | Viewed by 2656

Abstract

Palygorskite is a natural fibrous clay mineral that can be used in several applications, for which colloidal stability in aqueous suspensions is a key point to improve its performance. In this study, methods of magnetic stirring, high-speed shearing, and ultrasonication, as well as different chemical dispersants, combined with these methods, namely carboxymethylcellulose, alginate, polyphosphate, and polyacrylate, were used to improve the dispersibility and the formation of stable suspensions of palygorskite in different conditions of pH. The stability and particle size of suspensions with a low concentration of palygorskite were evaluated by visual inspection, optical and electron microscopy, dynamic light scattering, and zeta potential measurements. Moreover, the palygorskite used in this work was initially characterized for its mineralogical, chemical, physical, and morphological properties. It was found that more stable suspensions were produced with ultrasonication compared to the other two physical treatments, with magnetic stirring being inefficient in all tested cases, and for higher pH values (pH of 12 and pH of 8, the natural pH of the clay) when compared to lower pH values (pH of 3). Remarkably, combined with ultrasonication, carboxymethylcellulose or in a lesser extent polyphosphate at near neutral pH allowed for the disaggregation of crystal bundles of palygorskite into individualized crystals. These results may be helpful to optimize the performance of palygorskite in several domains where it is applied. Full article

(This article belongs to the Special Issue Bio-Based Polyelectrolytes: Development and Applications)

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13 pages, 1885 KiB

Open AccessArticle

Antibacterial Activity of N,O-Acylated Chitosan Derivative

by Agnieszka Piegat, Anna Żywicka, Agata Niemczyk and Agata Goszczyńska

Polymers 2021, 13(1), 107; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13010107 - 29 Dec 2020

Cited by 17 | Viewed by 2415

Abstract

The antibacterial activity of N,O-acylated chitosan derivative with linoleic acid (CH_LA) was tested by disc and well diffusion, agar impregnation and microdilution methods against Staphylococcus aureus, Escherichia coli and Helicobacter pylori strains. Hydrophobically modified chitosan (HMC) was expected to exhibit enhanced antibacterial activity and specific mucin interactions. Although diffusion tests have not indicated the antibacterial potential of chitosan (CH) or CH_LA, the results of the microdilution method demonstrated that tested polymers significantly reduced the amount of living bacteria cells in different concentrations depending on the microorganism. Additionally, CH_LA was characterized by enhanced antibacterial activity compared to CH, which may suggest a different mechanism of interaction with S. aureus and H. pylori. Furthermore, the UV-VIS analysis revealed that the amphiphilic character of derivative led to strong CH_LA–mucin interactions. The study proved the high potential of CH_LA in antibacterial applications, especially for the gastrointestinal tract. Full article

(This article belongs to the Special Issue Bio-Based Polyelectrolytes: Development and Applications)

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29 pages, 12277 KiB

Open AccessArticle

Evaluation of Anionic Eco-Friendly Flocculants Prepared from Eucalyptus Pulps with Diverse Lignin Contents for Application in Effluent Treatment

by Kinga Grenda, José A. F. Gamelas, Julien Arnold, Lorenzo Pellizzer, Olivier J. Cayre and Maria G. Rasteiro

Polymers 2021, 13(1), 25; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13010025 - 23 Dec 2020

Cited by 3 | Viewed by 2821

Abstract

Modification of cellulosic-rich materials for the production of cellulose-based polyelectrolytes (PELs) can bring several benefits, such as high biodegradability and low or no toxicity, for numerous applications, when compared with the use of traditional, synthetic PELs. Moreover, cellulose-based PELs originating from wood wastes, contribute to the valorisation of such wastes. In this work, Eucalyptus pulps with diverse lignin contents, extracted from Eucalyptus wood wastes, were anionized by a two–step reaction procedure (periodate oxidation followed by sulfonation). Applying different reaction times (24–144 h) in the sulfonation step allowed for producing a range of cellulose-based anionic PELs with different characteristics. PELs obtained after 24 and 72 h of sulfonation were thoroughly characterized (Fourier transform infrared and ¹H nuclear magnetic resonance spectroscopies, anionic group content (elemental analysis), zeta potential and hydrodynamic diameter (dynamic light scattering)) and subsequently evaluated as flocculants in decolouration processes of model effluents (Methylene Blue and Crystal Violet) and an industrial effluent from a textile industry. Furthermore, possible flocculation mechanisms induced by the use of the various PELs are discussed. Results are compared with those obtained with a commonly applied, synthetic flocculant (polyacrylamide). It is demonstrated that it was possible to obtain water-soluble lignocellulosic PELs starting from raw materials with different degrees of purity and that those PELs are promising eco-friendly alternative flocculation agents for the decolouration of effluents. Full article

(This article belongs to the Special Issue Bio-Based Polyelectrolytes: Development and Applications)

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12 pages, 2733 KiB

Open AccessArticle

Chitosan Films in Food Applications. Tuning Film Properties by Changing Acidic Dissolution Conditions

by Elodie Melro, Filipe E. Antunes, Gabriela J. da Silva, Inês Cruz, Philippe E. Ramos, Fátima Carvalho and Luís Alves

Polymers 2021, 13(1), 1; https://0-doi-org.brum.beds.ac.uk/10.3390/polym13010001 - 22 Dec 2020

Cited by 36 | Viewed by 4446

Abstract

Food contamination due to the presence of microorganisms is a serious problem. New food preservation systems are being studied to kill or inhibit spoilage and pathogenic microorganisms that contaminate food and reduce the shelf life of products. Chitosan films with potential application to food preservation have witnessed great developments during the last years. Chitosan is a cationic polysaccharide with the ability to form films and possess antimicrobial properties. It is water-insoluble but can be dissolved in acidic solutions. In the present work, three different acids (acetic, lactic and citric) were used in chitosan dissolution and both, the resultant solutions and formed films were characterized. It was observed that chitosan water-acetic acid systems show the highest antimicrobial activity due to the highest chitosan charge density, compared to the mixtures with lactic and citric acid. This system showed also the higher solution viscosity compared to the other systems. Chitosan–acetic acid films were also the ones presenting better mechanical properties; this can be attributed to the fact that lactic and citric acids remain in the films, changing their properties, which does not happen with acetic acid. Films produced from chitosan dissolved in water/acetic acid system are resistant, while very fragile but elastic films are formed when lactic acid is used. It was demonstrated that a good selection of the type of acid not only facilitates the dissolution of chitosan but also plays a key role in the properties of the formed solutions and films. Full article

(This article belongs to the Special Issue Bio-Based Polyelectrolytes: Development and Applications)

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18 pages, 2623 KiB

Open AccessArticle

Characterization of Two Cactus Formulation-Based Flocculants and Investigation on Their Flocculating Ability for Cationic and Anionic Dyes Removal

by Bouthaina Othmani, José A. F. Gamelas, Maria Graça Rasteiro and Moncef Khadhraoui

Polymers 2020, 12(9), 1964; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12091964 - 30 Aug 2020

Cited by 11 | Viewed by 3184

Abstract

Dye invasion in wastewaters is undeniably one of the crucial environmental concerns in addition to the supplement of toxic synthetic chemical flocculants used for color removal using the conventional coagulation-flocculation process. With the aim to improve the flocculation stage in terms of reagents safety and ensure dyes removal, the present study explores the flocculating effectiveness of two natural, stable, and eco-friendly cactus formulations, namely 60 °C oven-dried (DP) and lyophilized (LP) cladodes. Both formulations were assessed to treat cationic (Methylene blue; MB) and anionic (Methyl Orange; MO) dye solutions as a substitution attempt for the currently questioned employed synthetic chemical flocculants. Obtained results demonstrate that, in conjunction with alum as coagulant, the lyophilized powder (LP) bio-based flocculant appears to be the most efficient cactus formulation, showing a significant color (83%) and a turbidity (69%) abatement for the cationic dye (MB) and, respectively, 63% and 62% for the anionic one (MO). Additionally, the flocculation activity of the LP formula remained high over an eight-month period of storage. Moreover, based on the Fourier transform infrared (FTIR) spectroscopic analysis and the chemical characterization of cactus formulations, the occurring flocculation mechanisms of the dye removal are presumed to be based on both adsorption and bridging phenomena. Further, the significant color and turbidity decline achieved upon the addition of the lyophilized cactus cladodes powder (LP), enhancing thus the coagulation performance of the alum-based coagulant, proved the effectiveness of this bio-flocculant compared to the commonly used chemical flocculant (polyacrylamide). Hence, it was suggested that lyophilized cactus cladodes as a natural flocculant could be one of the effective surrogates to chemical flocculants conventionally used in wastewater treatment for the sake of a safer and sustainable environment. Full article

(This article belongs to the Special Issue Bio-Based Polyelectrolytes: Development and Applications)

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23 pages, 4742 KiB

Open AccessArticle

Uncommon Sorption Mechanism of Aromatic Compounds onto Poly(Vinyl Alcohol)/Chitosan/Maleic Anhydride-β-Cyclodextrin Hydrogels

by Cesar M. C. Filho, Pedro V. A. Bueno, Alan F. Y. Matsushita, Bruno H. Vilsinski, Adley F. Rubira, Edvani C. Muniz, Dina M. B. Murtinho and Artur J. M. Valente

Polymers 2020, 12(4), 877; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12040877 - 10 Apr 2020

Cited by 8 | Viewed by 3094

Abstract

Aromatic hydrocarbons are extensive environmental pollutants occurring in both water and air media, and their removal is a priority effort for a healthy environment. The use of adsorbents is among the several strategies used for the remediation of these compounds. In this paper, we aim the synthesis of an amphiphilic hydrogel with the potential for the simultaneous sorption of a set of monocyclic and polycyclic aromatic hydrocarbons associated with toxicity effects in humans. Thus, we start by the synthesis of a copolymer-based in chitosan and β-cyclodextrin previously functionalized with the maleic anhydride. The presence of β-cyclodextrin will confer the ability to interact with hydrophobic compounds. The resulting material is posteriorly incorporated in a cryogel of poly(vinyl alcohol) matrix. We aim to improve the amphiphilic ability of the hydrogel matrix. The obtained hydrogel was characterized by swelling water kinetics, thermogravimetric analysis, rheological measurements, and scanning electron microscopy. The sorption of aromatic hydrocarbons onto the gel is characterized by pseudo-first-order kinetics and Henry isotherm, suggesting a physisorption mechanism. The results show that the presence of maleic anhydride-β-cyclodextrin and chitosan into hydrogels leads to an increase in the removal efficiency of the aromatic compounds. Additionally, the capacity of this hydrogel for removing these pollutants from a fossil fuel sample has also been tested. Full article

(This article belongs to the Special Issue Bio-Based Polyelectrolytes: Development and Applications)

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Review

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20 pages, 8186 KiB

Open AccessEditor’s ChoiceReview

Structural Polymorphism of Single pDNA Condensates Elicited by Cationic Block Polyelectrolytes

by Kensuke Osada

Polymers 2020, 12(7), 1603; https://0-doi-org.brum.beds.ac.uk/10.3390/polym12071603 - 19 Jul 2020

Cited by 8 | Viewed by 3512

Abstract

DNA folding is a core phenomenon in genome packaging within a nucleus. Such a phenomenon is induced by polyelectrolyte complexation between anionic DNA and cationic proteins of histones. In this regard, complexes formed between DNA and cationic polyelectrolytes have been investigated as models to gain insight into genome packaging. Upon complexation, DNA undergoes folding to reduce its occupied volume, which often results in multi-complex associated aggregates. However, when cationic copolymers comprising a polycation block and a neutral hydrophilic polymer block are used instead, DNA undergoes folding as a single molecule within a spontaneously formed polyplex micelle (PM), thereby allowing the observation of the higher-order structures that DNA forms. The DNA complex forms polymorphic structures, including globular, rod-shaped, and ring-shaped (toroidal) structures. This review focuses on the polymorphism of DNA, particularly, to elucidate when, how, and why DNA organizes into these structures with cationic copolymers. The interactions between DNA and the copolymers, and the specific nature of DNA in rigidity; i.e., rigid but foldable, play significant roles in the observed polymorphism. Moreover, PMs serve as potential gene vectors for systemic application. The significance of the controlled DNA folding for such an application is addressed briefly in the last part. Full article

(This article belongs to the Special Issue Bio-Based Polyelectrolytes: Development and Applications)

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