Effect of solution plasma process with bubbling gas on physicochemical properties of chitosan

doi:10.1016/j.ijbiomac.2017.01.049

International Journal of Biological Macromolecules

Volume 98, May 2017, Pages 201-207

https://doi.org/10.1016/j.ijbiomac.2017.01.049 Get rights and content

Highlights

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Solution plasma process with bubbling gas was used to prepare oligochitosan.
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Addition of bubbling gas accelerated the rate of chitosan degradation.
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The main chitosan structure was not affected and was intact in the oligochitosans.

Abstract

In the present work, solution plasma process (SPP) with bubbling gas was used to prepare oligochitosan. The effect of SPP irradiation with bubbling gas on the degradation of chitosan was evaluated by the intrinsic viscosity reduction rate and the degradation kinetic. The formation of OH radical was studied. Changes of the physicochemical properties of chitosan were measured by scanning electron microscopy, X-ray diffraction, and thermogravimetric analysis, as well as ultraviolet-visible, Fourier-transform infrared, and ¹³C nuclear magnetic resonance spectroscopy. The results indicated an obvious decrease in the intrinsic viscosity reduction rate after SPP irradiation with bubbling gas, and that the rate with bubbling was higher than that without. The main chemical structure of chitosan remained intact after irradiation, but changes in the morphology, crystallinity, and thermal stability of oligochitosan were observed. In particular, the crystallinity and thermal stability tended to decrease. The present study indicated that SPP can be effectively used for the degradation of chitosan.

Introduction

Chitosan is a natural nontoxic polymer that is mainly composed of β (1–4)-linked glucosamine and N-acetylglucosamine. The polysaccharide has attracted tremendous research interest owing to its biological properties such as antimicrobial, hypocholesterolemic, immunity, and antitumor effects [1], [2]. However, its high molecular weight and low solubility in aqueous solvents has thus far limited its applications [3], [4]. Oligochitosan shows good solubility and some specific biological, chemical, and physical properties. Therefore, there has been increasing interest in methods for preparing oligochitosan by using a variety of techniques [5], [6], [7]. Solution plasma process (SPP) technology has been recognized as an advanced oxidation process. SPP involves the application of voltage to generate discharge plasma in a liquid, which leads to the formation of active radicals (H radical dot , O, OH) and molecules (e.g., H₂O₂, O₃) [8], [9], [10]. The oxidizing species can effectively degrade the recalcitrant organic substances such as pharmaceutical compounds, dioxins, or agricultural chemicals [11]. Especially, OH radicals play the critical role for the strong oxidation property of SPP technology [12]. The SPP method has been extensively applied in wastewater treatment owing to its excellent performance, including high degradation efficiency, complete degradation, no secondary pollution, and requirements of normal temperature, pressure and low power consumption [9], [13], [14].

In recent years, SPP has also been used to degrade chitosan. For example, the decomposition of chitosan was successfully achieved using a solution plasma system [7], [15]. However, the solution plasma was produced by pulsed discharge without bubbling gas. Bubbling gas is often used to improve the liquid discharge performance in pulsed discharge systems [16]. The injection of gas bubbles can significantly increase the contact surface area of the gas and liquid and enhance higher-energy electron production, thus resulting in the creation of more oxidizing species [17]. In addition, bubbling gas can enhance the mass transfer rate and increase the efficiency of the diffusion of reactive species into the liquid, thus promoting oxidation reactions [9]. We previously carried out studies on the degradation of chitosan by SPP in the presence of H₂O₂ with bubbling gas and concluded that this method could be used for effective degradation of chitosan [18]. At treatment time of 30 min, the intrinsic viscosity reduction rate reached 82.19% and 70.04% with and without bubbling gas, respectively. The results confirmed the decomposition effect of bubbling gas in pulsed discharge systems.

Therefore, in the present study, the effect of SPP with bubbling gas (air) on the degradation of chitosan was evaluated, and the characteristics of the chitosan obtained after SPP irradiation with bubbling gas were investigated, including the morphology, crystallinity, thermogravimetry, and chemical structure.

Section snippets

Materials

Chitosan was obtained from Sinopharm Chemical Reagent Co. Ltd., China. The degree of deacetylation ( $D D$ ) of chitosan is greater than 90%. The viscosity average molecular weight (Mv) of chitosan is 1138 kDa based on viscosity measurements [19]. Acetic acid, ethyl alcohol, and other chemicals were of analytical reagent grade and were obtained from Sinopharm Chemical Reagent Co. Ltd., China. All chemicals were used without any further purification.

Experimental setup

The experimental setup is shown in Fig. 1. The

Degradation of chitosan by SPP irradiation with bubbling gas

Fig. 2 shows a plot of the change in the intrinsic viscosity reduction rate of chitosan over irradiation time under SPP irradiation with and without bubbling gas. Overall, the intrinsic viscosity reduction rate of chitosan increased with increasing irradiation time, with an initial substantial increase within 120 min, followed by a more gradual increase. This pattern might be explained by the fact that chitosan consists of long molecular chains and a large amount of glycosidic bonds in the early

Conclusion

In the present study, the SPP method with bubbling gas was employed to prepare oligochitosan. The results showed that the degradation process of chitosan could be accelerated by applying bubbling gas compared with SPP alone. The SEM, TGA, and XRD analyses demonstrated that the crystalline structure and the chitosan chains of chitosan were destroyed with further degradation over longer treatment time. The results of UV–vis, FTIR, and ¹³C NMR spectroscopy showed that the main chain structure of

Acknowledgement

The study was supported by the 2014–2015 Research Funds for the Introduced Talents of Shenyang Agricultural University (20153033).

References (41)

A. Anitha et al.
Chitin and chitosan in selected biomedical applications
Prog. Polym. Sci.
(2014)
W.H. Xia et al.
Biological activities of chitosan and chitooligosaccharides
Food Hydrocolloid
(2011)
Q. Chen et al.
Hydrolysis of chitosan under microwave irradiation in ionic liquids promoted by sulfonic acid-functionalized ionic liquids
Polym. Degrad. Stab.
(2012)
P. Zou et al.
Advances in characterisation and biological activities of chitosan and chitosan oligosaccharides
Food Chem.
(2016)
N.Q. Hien et al.
Degradation of chitosan in solution by gamma irradiation in the presence of hydrogen peroxide
Carbohydr. Polym.
(2012)
Q.Z. Huang et al.
Heterogeneous degradation of chitosan with H₂O₂ catalysed by phosphotungstate
Carbohydr. Polym.
(2008)
I. Prasertsung et al.
Preparation of low molecular weight chitosan using solution plasma system
Carbohydr. Polym.
(2012)
B. Jiang et al.
Degradation of azo dye using non-thermal plasma advanced oxidation process in a circulatory airtight reactor system
Chem. Eng. J.
(2012)
B. Jiang et al.
Review on electrical discharge plasma technology for wastewater remediation
Chem. Eng. J.
(2014)
G.R. Stratton et al.
Plasma-based water treatment: conception and application of a new general principle for reactor design
Chem. Eng. J.
(2015)

H. Zhang et al.

Degradation of microcystin-LR in water by glow discharge plasma oxidation at the gasesolution interface and its safety evaluation

Water Res.

(2012)

H. Ge et al.

Parameter optimization of excited OH radical in multi-needle to plate negative DC corona discharge

J. Electrostat.

(2011)

F.M. Huang et al.

Degradation of methyl orange by atmospheric DBD plasma: analysis of the degradation effects and degradation path

J. Electrostat.

(2012)

B. Sun et al.

Characteristics of gas-liquid pulsed discharge plasma reactor and dye decoloration efficiency

J. Environ. Sci.

(2012)

T. Tantiplapol et al.

Influences of solution plasma conditions on degradation rate and properties of chitosan

Innov. Food Sci. Emerg.

(2015)

W.J. Bian et al.

Actions of nitrogen plasma in the 4-chrolophenol degradation by pulsed high-voltage discharge with bubbling gas

Chem. Eng. J.

(2013)

H. Zhang et al.

Inactivation of Microcystis aeruginosa by DC glow discharge plasma: impacts on cell integrity, pigment contents and microcystins degradation

J. Hazard. Mater.

(2014)

J. Huang et al.

Biochemical activities of low molecular weight chitosans derived from squid pens

Carbohydr. Polym.

(2012)

Y.C. Huang et al.

Degradation of chitosan by hydrodynamic cavitation

Polym. Degrad. Stab.

(2013)

B. Sun et al.

Optical study of active species produced by a pulsed streamer corona discharge in water

J. Electrostat.

(1997)

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View full text

Effect of solution plasma process with bubbling gas on physicochemical properties of chitosan

Highlights

Abstract

Introduction

Section snippets

Materials

Experimental setup

Degradation of chitosan by SPP irradiation with bubbling gas

Conclusion

Acknowledgement

Prog. Polym. Sci.

Food Hydrocolloid

Polym. Degrad. Stab.

Food Chem.

Carbohydr. Polym.

Carbohydr. Polym.

Carbohydr. Polym.

Chem. Eng. J.

Chem. Eng. J.

Chem. Eng. J.

Water Res.

J. Electrostat.

J. Electrostat.

J. Environ. Sci.

Innov. Food Sci. Emerg.

Chem. Eng. J.

J. Hazard. Mater.

Carbohydr. Polym.

Polym. Degrad. Stab.

J. Electrostat.