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Chitin and Chitosan: Properties 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 (30 September 2019) | Viewed by 58759

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Prof. Dr. San-Lang Wang

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Department of Chemistry/Life Science Development Center, Tamkang University, New Taipei City 25137, Taiwan
Interests: marine chitin; applied microbiology; enzyme inhibitors; antidiabetic drugs
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

This Special Issue is dedicated to chitin and chitosan: properties and applications. The development of new polymer materials has recently become an extremely fascinating research topic, especially in relation to chitin and chitosan. Chitin, chitosan, and their derivatives hold great economic merit due to their versatile activities and biotechnological applications. Chitin and chitosan are traditionally prepared from chitin-containing fishery processing (shrimp shells, crab shells, and squid pens) through various procedures including chemical, enzymatic, and microbial treatments. For improving their properties, chemical modifications have also been intensively studied. Compared to synthetic polymers, chitin and their derivatives have advantages of being biocompatible, biodegradable and sustainable.

The aim of this Special Issue is to discuss their manufacturing, modification, characterization, as well as their various physical and chemical applications in biomedical and green industry fields. Both research and review articles are welcome.

Prof. San-Lang Wang
Guest Editor

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Keywords

Chitin/chitosan
Chitin/chitosan modification
Chitin/chitosan film, chitin/chitosan fiber, chitin/chitosan gel
Chitin/chitosan oligomer
Chitinase/chitosanase
Biomacromolecules and functional materials
Chitin/chitosan polymer design and characterization
Chitin/chitosan physical and chemical properties

Published Papers (14 papers)

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Research

14 pages, 4251 KiB

Open AccessArticle

Biological Effects of Chitosan-Based Dressing on Hemostasis Mechanism

by Yi-Wen Wang, Chuan-Chieh Liu, Juin-Hong Cherng, Chien-Seng Lin, Shu-Jen Chang, Zhi-Jie Hong, Cheng-Che Liu, Yaw-Kwan Chiu, Sheng-Der Hsu and Hung Chang

Polymers 2019, 11(11), 1906; https://doi.org/10.3390/polym11111906 - 19 Nov 2019

Cited by 41 | Viewed by 4552

Abstract

There have been numerous recent advances in wound care management. Nevertheless, the assessment of hemostatic dressing is essential to enable surgeons and other physicians and healthcare professionals to make the correct decisions regarding the disposition of severe hemorrhage. Here, we investigated the relative efficacies of chitosan-based and conventional gauze dressings in a rat model of femoral artery hemorrhage and in patients with surgical wounds. Dressing effectiveness was evaluated based on hemostatic profiles, biocompatibility, antimicrobial activity, and blood factor responses in coagulation. Relative to standard gauze dressing, the chitosan fiber (CF) dressing treatment significantly shortened the time to hemostasis in injured rats. Moreover, the CF dressing significantly prolonged partial thromboplastin time, enhanced blood absorption, and reduced antithrombin production without altering the prothrombin ratio. Unlike regular gauze bandages, the CF dressing demonstrated remarkable antibacterial activity. The results of this study indicate the effectiveness of chitosan as a hemostatic dressing and elucidate its underlying mechanism. It is possible that chitosan surgical dressings could serve as first-line intervention in hospital emergency care for uncontrolled hemorrhage. Full article

(This article belongs to the Special Issue Chitin and Chitosan: Properties and Applications)

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17 pages, 4149 KiB

Open AccessArticle

The Production Possibility of the Antimicrobial Filaments by Co-Extrusion of the PLA Pellet with Chitosan Powder for FDM 3D Printing Technology

by Szymon Mania, Jacek Ryl, Jia-Rong Jinn, Ya-Jane Wang, Anna Michałowska and Robert Tylingo

Polymers 2019, 11(11), 1893; https://doi.org/10.3390/polym11111893 - 16 Nov 2019

Cited by 24 | Viewed by 4711

Abstract

The last decades have witnessed a major advancement and development in three-dimensional (3D) printing technology. In the future, the trend’s utilization of 3D printing is expected to play an important role in the biomedical field. This work presents co-extrusion of the polylactic acid (PLA), its derivatives (sPLA), and chitosan with the aim of achieving filaments for printing 3D objects, such as biomedical tools or implants. The physicochemical and antimicrobial properties were evaluated using SEM, FT-IR, DSC, instrumental mechanical test, and based on the ASTM E2149 standard, respectively. The addition of chitosan in the PLA and sPLA filaments increased their porosity and decreased density. The FT-IR analysis showed that PLA and chitosan only formed a physical mixture after extrusion. The addition of chitosan caused deterioration of the mechanical properties of filaments, especially elongation at break and Young’s modulus. The addition of chitosan to the filaments improved their ability to crystallize and provide their antimicrobial properties against Escherichia coli and Staphylococcus aureus. Full article

(This article belongs to the Special Issue Chitin and Chitosan: Properties and Applications)

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21 pages, 4280 KiB

Open AccessArticle

The Effect of PEGDE Concentration and Temperature on Physicochemical and Biological Properties of Chitosan

by Martha Gabriela Chuc-Gamboa, Rossana Faride Vargas-Coronado, José Manuel Cervantes-Uc, Juan Valerio Cauich-Rodríguez, Diana María Escobar-García, Amaury Pozos-Guillén and Julio San Román del Barrio

Polymers 2019, 11(11), 1830; https://doi.org/10.3390/polym11111830 - 07 Nov 2019

Cited by 19 | Viewed by 5039

Abstract

Chitosan (CHT) is a polysaccharide with multiple claimed properties and outstanding biocompatibility, generally attributed to the presence of protonable amino groups rendering a cationic natural polymer. However, the effect of changes in CHT structure due to hydration is not considered in its performance. This study compares the effects on biocompatibility after drying at 25 °C and 150 °C scaffolds of chitosan, polyethylene glycol diglycidyl ether (PEGDE) crosslinked CHT (low, medium and high concentration) and glutaraldehyde (GA) crosslinked CHT. PEGDE crosslinked CHT showed a reduction in free amino groups and the amide I/II ratio, which exhaustive drying reduced further. In X-ray diffraction (DRX) analysis, PEGDE crosslinked CHT showed multiple peaks, whereas the crystallinity percentage was reduced with an increase in PEGDE concentration and thermal treatments at 150 °C. In a direct contact cell assay, high osteoblast viability was achieved at low and medium PEDGE concentrations, which was improved when the crosslinked scaffolds were thermally treated at 150 °C. This was attributed to its partial hydrophilicity, low crystallinity and low surface roughness; this in spite of the small reduction in the amount of free amino groups on the surface induced during drying at 150 °C. Furthermore, PEGDE crosslinked CHT scaffolds showed strong vinculin and integrin 1β expression, which render them suitable for bone contact applications. Full article

(This article belongs to the Special Issue Chitin and Chitosan: Properties and Applications)

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13 pages, 2400 KiB

Open AccessArticle

Anti-Oxidant and Anti-Diabetes Potential of Water-Soluble Chitosan–Glucose Derivatives Produced by Maillard Reaction

by Thi Ngoc Tran, Chien Thang Doan, Van Bon Nguyen, Anh Dzung Nguyen and San-Lang Wang

Polymers 2019, 11(10), 1714; https://doi.org/10.3390/polym11101714 - 18 Oct 2019

Cited by 37 | Viewed by 3755

Abstract

Chitosan-sugar derivatives demonstrate some useful biology activities (for example anti-oxidant and anti-microbial activities). In this study, water-soluble chitosan–glucose derivatives (WSCGDs) were produced from a water-soluble chitosan hydrochloride (WSC) with 12.5 kDa of molecular weight and 24.05% of degree of acetylation (DA) via Maillard reaction with the heating temperatures of 100 °C and 121 °C. The Maillard reaction between WSC and glucose was investigated by measuring the absorbances at 420 nm and 294 nm, indicating that the reaction took place more effectively at 121 °C. All WSCGDs exhibited higher anti-oxidant activity than WSC, in which WSCGDs obtained at the treatment 121 °C for 2 h, 3 h, and 4 h expressed the highest ability (IC50 range from 1.90–1.05 mg/mL). Increased anti-α-amylase and anti-α-glucosidase activities were also observed in WSCGDs from the treatment at 121 °C. In detail, the highest IC50 values of anti-α-amylase activity were 18.02 mg/mL (121 °C, 3 h) and 18.37 mg/mL (121 °C, 4 h), whereas the highest IC50 values of anti-α-glucosidase activity were in range of 7.09–5.72 mg/mL (121 °C, for 1–4 h). According to the results, WSCGD obtained from 121 °C for 3 h was selected for further characterizing by high performance liquid chromatography size exclusion chromatography (HPLC SEC), colloid titration, FTIR, as well as 1H-NMR, indicating that the derivative of WSC and glucose was successfully synthesized with a molecular weight of 15.1 kDa and degree of substitution (DS) of 34.62 ± 2.78%. By expressing the excellent anti-oxidant and anti-diabetes activities, WSCGDs may have potential use in health food or medicine applications. Full article

(This article belongs to the Special Issue Chitin and Chitosan: Properties and Applications)

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11 pages, 4647 KiB

Open AccessArticle

Cytocompatible and Antibacterial Properties of Chitosan-Siloxane Hybrid Spheres

by Yuki Shirosaki, Manato Nakatsukasa, Saki Yasutomi, Susana Cruz-Neves, Satoshi Hayakawa, Akiyoshi Osaka, Toshinari Maeda and Toshiki Miyazaki

Polymers 2019, 11(10), 1676; https://doi.org/10.3390/polym11101676 - 14 Oct 2019

Cited by 3 | Viewed by 2296

Abstract

Microporous spheres in a hybrid system consisting of chitosan and γ-glycidoxypropyltrimethoxysilane (GPTMS) have advantages in a range of applications, e.g., as vehicles for cell transplantation and soft tissue defect filling materials, because of their excellent cytocompatibility with various cells. In this study, microporous chitosan-GPTMS spheres were prepared by dropping chitosan-GPTMS precursor sols, with or without a cerium chloride, into liquid nitrogen using a syringe pump. The droplets were then freeze dried to give the pores of size 10 to 50 μm. The cell culture tests showed that L929 fibroblast-like cells migrated into the micropores larger than 50 μm in diameter, whereas MG63 osteoblast-like cells proliferated well and covered the granule surfaces. The spheres with cerium chloride showed antibacterial properties against both gram-negative and gram-positive bacteria. Full article

(This article belongs to the Special Issue Chitin and Chitosan: Properties and Applications)

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14 pages, 2345 KiB

Open AccessArticle

An Exochitinase with N-Acetyl-β-Glucosaminidase-Like Activity from Shrimp Head Conversion by Streptomyces speibonae and Its Application in Hydrolyzing β-Chitin Powder to Produce N-Acetyl-d-Glucosamine

by Thi Ngoc Tran, Chien Thang Doan, Minh Trung Nguyen, Van Bon Nguyen, Thi Phuong Khanh Vo, Anh Dzung Nguyen and San-Lang Wang

Polymers 2019, 11(10), 1600; https://doi.org/10.3390/polym11101600 - 30 Sep 2019

Cited by 26 | Viewed by 3938

Abstract

Marine chitinous byproducts possess significant applications in many fields. In this research, different kinds of fishery chitin-containing byproducts from shrimp (shrimp head powder (SHP) and demineralized shrimp shell powder), crab (demineralized crab shell powder), as well as squid (squid pen powder) were used to provide both carbon and nitrogen (C/N) nutrients for the production of an exochitinase via Streptomyces speibonae TKU048, a chitinolytic bacterium isolated from Taiwanese soils. S. speibonae TKU048 expressed the highest exochitinase productivity (45.668 U/mL) on 1.5% SHP-containing medium at 37 °C for 2 days. Molecular weight determination analysis basing on polyacrylamide gel electrophoresis revealed the mass of TKU048 exochitinase was approximately 21 kDa. The characterized exochitinase expressed some interesting properties, for example acidic pH optima (pH 3 and pH 5–7) and a higher temperature optimum (60 °C). Furthermore, the main hydrolysis mechanism of TKU048 exochitinase was N-acetyl-β-glucosaminidase-like activity; its most suitable substrate was β-chitin powder. The hydrolysis experiment revealed that TKU048 exochitinase was efficient in the cleavage of β-chitin powder, thereby releasing N-acetyl-d-glucosamine (GlcNAc, monomer unit of chitin structure) as the major product with 0.335 mg/mL of GlcNAc concentration and a yield of 73.64% after 96 h of incubation time. Thus, TKU048 exochitinase may have potential in GlcNAc production due to its N-acetyl-β-glucosaminidase-like activity. Full article

(This article belongs to the Special Issue Chitin and Chitosan: Properties and Applications)

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14 pages, 3290 KiB

Open AccessArticle

Influence of Nano Titanium Dioxide and Clove Oil on Chitosan–Starch Film Characteristics

by Wei Li, Kewang Zheng, Hujian Chen, Shirong Feng, Wei Wang and Caiqin Qin

Polymers 2019, 11(9), 1418; https://doi.org/10.3390/polym11091418 - 29 Aug 2019

Cited by 47 | Viewed by 5141

Abstract

The combined effects of nano titanium dioxide (TiO₂-N) and clove oil (CO) on the physico-chemical, biological and structural properties of chitosan (CH)/starch (ST) films were investigated by using a solvent casting method. Results indicated that the incorporation of TiO₂-N could improve the compactness of the film, increase the tensile strength (TS) and antioxidant activity, and decrease the water vapour permeability (WVP). As may be expected, the incorporation of CO into the film matrix decreased TS but increased the hydrophobicity as well as water vapour barrier antimicrobial and antioxidant properties. Fourier-transform infrared spectroscopy (FTIR) data supported intermolecular interactions between TiO₂-N, CO and the film matrix. Use of a scanning electron microscope (SEM) showed that TiO₂-N and CO were well dispersed and emulsified in the film network. Thermogravimetric (TG) and derivative thermogravimetric (DTG) curves demonstrated that TiO₂-N and CO were well embedded in the film matrix, hence this blend film system could provide new formulation options for food packaging materials in the future. Full article

(This article belongs to the Special Issue Chitin and Chitosan: Properties and Applications)

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15 pages, 3557 KiB

Open AccessArticle

Preparation of Modified Chitosan Microsphere-Supported Copper Catalysts for the Borylation of α,β-Unsaturated Compounds

by Wei Wang, Zufeng Xiao, Chaofan Huang, Kewang Zheng, Yin Luo, Yumin Dong, Zitong Shen, Wei Li and Caiqin Qin

Polymers 2019, 11(9), 1417; https://doi.org/10.3390/polym11091417 - 28 Aug 2019

Cited by 8 | Viewed by 3171

Abstract

Chitosan microspheres modified by 2-pyridinecarboxaldehyde were prepared and used in the construction of a heterogeneous catalyst loaded with nano-Cu prepared by a reduction reaction. The chemical structure of the catalyst was investigated by Fourier Transform Infrared Spectroscopy (FT-IR), Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), and X-ray Photoelectron Spectroscopy (XPS). Under mild conditions, such as no ligand at room temperature, the catalyst was successfully applied to catalyze the borylation of α,β-unsaturated receptors in a water-methanol medium, yielding 17%–100% of the corresponding β-hydroxy product. Even after repeated use five times, the catalyst still exhibited excellent catalytic activity. Full article

(This article belongs to the Special Issue Chitin and Chitosan: Properties and Applications)

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9 pages, 3479 KiB

Open AccessArticle

CuS@Corn Stalk/Chitin Composite Hydrogel for Photodegradation and Antibacterial

by Yutong Xiong, Bichong Luo, Guixin Chen, Jihai Cai, Qimeng Jiang, Bin Gu and Xiaoying Wang

Polymers 2019, 11(9), 1393; https://doi.org/10.3390/polym11091393 - 24 Aug 2019

Cited by 22 | Viewed by 4507

Abstract

Copper sulfide nanoparticles (CuS NPs) have recently attracted extensive attention in various fields due to their excellent optical and electrical properties. However, CuS NPs are easy to agglomerate in their preparation on account of the high surface activity. In this study, uniform dispersion of CuS NPs were fabricated with corn stalk as a template and stabilizer, further CuS@corn stalk/chitin composite hydrogel was obtained by crosslinking with chitin. The results reveal that the CuS NPs were evenly dispersed into the composite hydrogels with a three-dimensional network structure, which were verified by the UV-vis spectrum, XRD, FT-IR spectra and SEM. In addition, the as-prepared composite hydrogel with the traits of peroxidase-like activity can convert H₂O₂ into an extremely oxidative and toxic ·OH, which manifested good effects for photodegradation of RhB and antibacterial against Escherichia coli and Staphylococcus aureus. Hence, the composite hydrogels could be used for photocatalytic treatment and sterilization of wastewater, which provides a new idea for the functional application of CuS NPs. Full article

(This article belongs to the Special Issue Chitin and Chitosan: Properties and Applications)

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20 pages, 5042 KiB

Open AccessArticle

The Use of Lanthanum Ions and Chitosan for Boron Elimination from Aqueous Solutions

by Joanna Kluczka, Gabriela Dudek, Alicja Kazek-Kęsik, Małgorzata Gnus, Maciej Krzywiecki, Krzysztof Mitko and Katarzyna Krukiewicz

Polymers 2019, 11(4), 718; https://doi.org/10.3390/polym11040718 - 19 Apr 2019

Cited by 9 | Viewed by 4218

Abstract

Boron is an essential element for plants and living organisms; however, it can be harmful if its concentration in the environment is too high. In this paper, lanthanum(III) ions were introduced to the structure of chitosan via an encapsulation technique and the obtained hydrogel (La-CTS) was used for the elimination of the excess of B(III) from modelling solutions. The reaction between boric acid and hydroxyl groups bound to the lanthanum coordinated by chitosan active centres was the preponderant mechanism of the bio-adsorption removal process. The results demonstrated that La-CTS removed boric acid from the aqueous solution more efficiently than either lanthanum hydroxide or native chitosan hydrogel, respectively. When the initial boron concentration was 100 mg/dm³, the maximum adsorption capacity of 11.1 ± 0.3 mg/g was achieved at pH 5 and the adsorption time of 24 h. The successful introduction of La(III) ions to the chitosan backbone was confirmed by Scanning Electron Microscopy with Energy Dispersive X-Ray Spectroscopy, Fourier-Transform Infrared Spectroscopy, X-Ray Diffraction, X-ray Photoelectron Spectroscopy, and Inductively Coupled Plasma Optical Emission Spectroscopy. Due to its high-performance boron adsorption-desorption cycle and convenient form, La-CTS seems to be a promising bio-adsorbent for water treatment. Full article

(This article belongs to the Special Issue Chitin and Chitosan: Properties and Applications)

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11 pages, 3743 KiB

Open AccessArticle

The Modulation of Chitosan-DNA Interaction by Concentration and pH in Solution

by Fangqin Ma, Yanwei Wang and Guangcan Yang

Polymers 2019, 11(4), 646; https://doi.org/10.3390/polym11040646 - 09 Apr 2019

Cited by 19 | Viewed by 3108

Abstract

Chitosan has been widely used to prepare a DNA carrier for highly efficient and non-toxic gene therapy. In the present study, we investigated DNA charge neutralization and compaction by chitosan in solutions of various pH levels by dynamic light scattering (DLS), magnetic tweezers (MT), and atomic force microscopy (AFM). We found that when chitosan concentration is higher than a critical value (0.2 µM), corresponding the ratio of phosphate and NH₂ in chitosan

k = 1.9

, the electrophoretic mobility of DNA-chitosan complex maintains an almost constant value when pH of solution is less 6.5, the isoelectric point of chitosan. Then it decreases with increasing pH of solution. However, when chitosan concentration is lower than the critical value, the mobility of the complex increases with pH in the range of acidity and reaches the maximum when the pH of the solution approaches the isoelectric point of chitosan. It finally decreases with increasing pH in solutions. The corresponding condensing force of the DNA-chitosan complex measured by single molecular MT changes accordingly with its charge neutralization in the same solution concentration (20 µM) and is consistent with the DLS measurements. This phenomenon might be related to the weakening interaction between DNA and chitosan in low pH solutions, and is verified by measuring the ratio of free chitosan to DNA complex in solutions. We also observed the various morphologies of DNA-chitosan complexes, such as ring, rod, flower, braid, and other structures, under different degrees of deacetylation, molecular weight, solution concentration and pH in solutions by AFM. Full article

(This article belongs to the Special Issue Chitin and Chitosan: Properties and Applications)

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11 pages, 3129 KiB

Open AccessArticle

Synthesis of Self-Healing Waterborne Polyurethane Systems Chain Extended with Chitosan

by Dae-Il Lee, Seung-Hyun Kim and Dai-Soo Lee

Polymers 2019, 11(3), 503; https://doi.org/10.3390/polym11030503 - 15 Mar 2019

Cited by 17 | Viewed by 4577

Abstract

In this study, the self-healing properties of waterborne polyurethane (WPU) were implemented by chitosan as a chain extender of polyurethane prepolymers. The physical properties and self-healing efficiency of WPU were studied by changing the molar fractions of chitosan from 0.1 to 0.3. After thermal treatment for 24 h at 110 °C, the self-healing efficiency for the tensile strength of the highest chitosan content (WPU-C3) was found to be 47%. The surface scratch was also completely restored. The efficiency of the sample with the lowest chitosan content (WPU-C1) was found to be 35%, while that of the control sample without chitosan (WPU-C0) was 4%. The self-healing properties of the as-prepared films were attributed to the exchange reactions between the hydroxyl groups of chitosan and the urethane groups in the films at elevated temperature. It is inferred that self-healing WPU can be synthesized by chain extension with chitosan. Full article

(This article belongs to the Special Issue Chitin and Chitosan: Properties and Applications)

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24 pages, 3157 KiB

Open AccessEditor’s ChoiceArticle

Chitosan Grafted Adsorbents for Diclofenac Pharmaceutical Compound Removal from Single-Component Aqueous Solutions and Mixtures

by Areti Tzereme, Evi Christodoulou, George Z. Kyzas, Margaritis Kostoglou, Dimitrios N. Bikiaris and Dimitra A. Lambropoulou

Polymers 2019, 11(3), 497; https://doi.org/10.3390/polym11030497 - 14 Mar 2019

Cited by 45 | Viewed by 4643

Abstract

The main purpose of this study was to investigate the synthesis of some cross-linked carboxyl-grafted chitosan derivatives to be used as selective adsorbents for diclofenac (DCF) pharmaceutical compounds from aqueous mixtures. Four different materials were synthesized using succinic anhydride (CsSUC), maleic anhydride (CsMAL), itaconic acid (CsITA), and trans-aconitic acid (CsTACON) as grafting agents. After synthesis, scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) were performed before and after DCF adsorption. In addition, a complete adsorption evaluation was carried out for all materials studying some important parameters. The optimum pH was 4; the amino groups of DCF can be protonated at pH = 4 (–NH⁺), so this groups can easily attract the clear negatively carboxyl moieties (–COO⁻) of the chitosan adsorbents. The Q_m for CsTACON was higher than those of the other materials, at all temperatures studied. By altering the temperature from 25 to 35 °C, an increase (16%) of Q_m (from 84.56 to 98.34 mg g⁻¹) was noted, while similar behavior was revealed after a further increase of temperature from 35 to 45 °C, improving by 5% (from 98.34 to 102.75 mg g⁻¹). All isotherms were fitted to Langmuir, Freundlich, and Langmuir-Freundlich (L-F) models). In addition, a kinetic model was proposed taking into account not only the interactions but also the diffusivity of the molecule (DCF) into the polymeric network. The behavior of the prepared chitosan materials in simultaneously removing other compounds (synergetic or antagonistic) was also evaluated by experiments performed in mixtures. DCF presented the highest removal from the mixture in the order: CsTACON (92.8%) > CsITA (89.5%) > CsSUC (80.9%) > CsMAL (66.2%) compared to other pharmaceutical compounds (salicylic acid, ibuprofen and ketoprofen). Desorption was achieved by using different eluants (either water or organic). The highest desorption ability was found for acetone (100% for CsTACON, CsSUC, CsMAL and 77% for CsITA) for all materials. Full article

(This article belongs to the Special Issue Chitin and Chitosan: Properties and Applications)

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20 pages, 3716 KiB

Open AccessArticle

Synthesis, Characterization, and Sludge Dewaterability Evaluation of the Chitosan-Based Flocculant CCPAD

by Chunhong Shi, Wenquan Sun, Yongjun Sun, Lei Chen, Yanhua Xu and Mengdan Tang

Polymers 2019, 11(1), 95; https://doi.org/10.3390/polym11010095 - 08 Jan 2019

Cited by 25 | Viewed by 3685

Abstract

Carboxymethyl chitosan (CMCS), acrylamide, and methacryloxyethyltrimethyl ammonium chloride were used as co-monomers to produce a sludge dewatering agent carboxymethyl chitosan-graft-poly(acrylamide-methacryloxyethyltrimethyl ammonium chloride) (CCPAD) by UV-induced graft polymerization. Single-factor experiments and response surface methodology were employed to investigate and optimize the grafting rate, grafting efficiency, and intrinsic viscosity influenced by the total monomer concentration, CMCS concentration, cationic degree, pH value, and illumination time. The structure, surface morphology, and thermal stability of CCPAD were characterized by infrared spectroscopy, hydrogen nuclear magnetic resonance, X-ray diffraction, scanning electron microscopy, and differential thermal-thermogravimetry. The raw sludge with 97.9% water content was sourced from the concentrated tank of a sewage treatment plant and used in the sludge condition experiments. In addition, CCPAD was applied as the sludge conditioner to investigate the effects of cationic degree, intrinsic viscosity, and pH on the supernatant turbidity, moisture content, specific resistance to filtration, and sludge settling ratio. Moreover, the mechanism of sludge conditioning by CCPAD was discussed by examining the zeta potential and extracellular polymeric substance (EPS) content of the supernatant. The sludge dewatering results confirmed that CCPAD had excellent performance for improving sludge dewaterability. Full article

(This article belongs to the Special Issue Chitin and Chitosan: Properties and Applications)

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