Kinetics of oxidation of an arabinogalactan from larch (Larix sibirica L.) in an aqueous medium in the presence of hydrogen peroxide

Борисов, И. М.; Широкова, Е. Н.; Mudarisova, R. Kh.; Муслухов, Р. Р.; Zimin, Yu. S.; Медведева, С. А.; Толстиков, Г. А.; Monakov, Yu. B.

doi:10.1023/b:rucb.0000030804.76265.60

Cited by 13 publications

(3 citation statements)

References 8 publications

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“…Non-selective oxidation of cellulose can be performed in a wide variety of oxidative systems, in the presence of nitrogen oxides [ 75 , 76 ], nitrates and nitrites [ 77 ], peroxides [ 78 ], sodium chlorite [ 79 ], permanganates [ 80 , 81 ], and even ozone [ 82 , 83 ] or lead (IV) tetraacetate [ 77 ] as non-specific oxidants. Most of these reactions occur under severe conditions (aggressive pH, high pressure, elevated temperature) and entail chemical degradation reactions (depolymerization) along with the synthesis of functionalized cellulose.…”

Section: Selective Oxidation Of Cellulose By Different Methodsmentioning

confidence: 99%

Selective Oxidation of Cellulose—A Multitask Platform with Significant Environmental Impact

Duceac¹,

Tanasă²,

Coseri³

2022

Materials

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Raw cellulose, or even agro-industrial waste, have been extensively used for environmental applications, namely industrial water decontamination, due to their effectiveness, availability, and low production cost. This was a response to the increasing societal demand for fresh water, which made the purification of wastewater one of the major research issue for both academic and industrial R&D communities. Cellulose has undergone various derivatization reactions in order to change the cellulose surface charge density, a prerequisite condition to delaminate fibers down to nanometric fibrils through a low-energy process, and to obtain products with various structures and properties able to undergo further processing. Selective oxidation of cellulose, one of the most important methods of chemical modification, turned out to be a multitask platform to obtain new high-performance, versatile, cellulose-based materials, with many other applications aside from the environmental ones: in biomedical engineering and healthcare, energy storage, barrier and sensing applications, food packaging, etc. Various methods of selective oxidation have been studied, but among these, (2,2,6,6-tetramethylpiperidin-1-yl)oxyl) (TEMPO)-mediated and periodate oxidation reactions have attracted more interest due to their enhanced regioselectivity, high yield and degree of substitution, mild conditions, and the possibility to further process the selectively oxidized cellulose into new materials with more complex formulations. This study systematically presents the main methods commonly used for the selective oxidation of cellulose and provides a survey of the most recent reports on the environmental applications of oxidized cellulose, such as the removal of heavy metals, dyes, and other organic pollutants from the wastewater.

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Section: Selective Oxidation Of Cellulose By Different Methodsmentioning

confidence: 99%

Selective Oxidation of Cellulose—A Multitask Platform with Significant Environmental Impact

Duceac¹,

Tanasă²,

Coseri³

2022

Materials

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confidence: 98%

“…The low-molecular-weight fractions were prepared by oxidative destruction of AG using H 2 O 2 and atmospheric oxygen in aqueous medium. The structures of the oxidized AG fractions were previously reported [5].The modified compounds were obtained by reacting 5-ASA with AG and its oxidized fractions in water at pH 7. The synthesized compounds are light-violet to black powders that are very soluble in water but insoluble in acetone, alcohols, and ether.…”

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confidence: 99%

Arabinogalactan Poly- and Oligosaccharides Modified with 5-Aminosalicylic Acid

et al. 2005

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Arabinogalactan poly-and oligosaccharides from Siberian larch (Larix sibirica L.) were modified with 5-aminosalicylic acid. The chemical composition and certain physicochemical properties were studied. The optimal conditions for preparing the modified compounds were found. These compounds were demonstrated to possess anti-ulcer and anti-inflammatory activity in tests on experimental animals.One of the methods for creating improved forms of medicinal compounds is their modification with natural polysaccharides. Among the polysaccharides that can be used for this purpose, arabinogalactan (AG) isolated by aqueous extraction from wood of the Siberian larch is of great interest because it is very soluble in water and has biological activity [1-4]. The use of water-soluble oxidized macromolecules and oligomers of AG as a polymeric matrix for formulating medicinal preparations is currently of great interest.We investigated the reaction of AG and its oxidized low-moleclar-weight fractions with an anti-ulcer preparation of 5-aminosalicylic acid (5-ASA). The low-molecular-weight fractions were prepared by oxidative destruction of AG using H 2 O 2 and atmospheric oxygen in aqueous medium. The structures of the oxidized AG fractions were previously reported [5].The modified compounds were obtained by reacting 5-ASA with AG and its oxidized fractions in water at pH 7. The synthesized compounds are light-violet to black powders that are very soluble in water but insoluble in acetone, alcohols, and ether. The natural arabinogalactan (AG na ) and polymeric (AG pol ) and oligomeric (AG ol ) fractions of oxidized polysaccharide were modified by reaction with 5-ASA, which has carboxylic, hydroxyl, and amino groups. It can be assumed that 5-ASA, like salicylic acid, is a relatively weak acid that will be partially dissociated in aqueous medium. Therefore, the form (molecular or ionized) of 5-ASA that reacts with AG must be determined. Thus, the dissociation constants of the carboxylic and hydroxyl groups of salicylic acid are K a = 1·10 -3 (pK a = 3.00) and K a = 1.5·10 -14 (pK a = 13.82), respectively [6]. Apparently these functional groups in 5-ASA are weakly dissociated. The presence of amino groups in 5-ASA typifies it also as an organic base that can accept its own protons formed by dissociation. As a result, it is obvious that the degree of dissociation of the carboxylic groups of 5-ASA should increase. Therefore, aqueous solutions of 5-ASA will contain not only acid molecules but also bipolar + H 3 NC 6 H 3 (OH)COO -ions. Dissociation of sodium salts of the acid (prepared by neutralization of an aqueous solution of the acid with base) in neutral medium will also form H 2 NC 6 H 3 (OH)COO -ions. In acid medium, + H 3 NC 6 H 3 (OH)COOH ions will most likely dominate; in basic medium, H 2 NC 6 H 3 (OH)COO -. Changing the pH of a solution is known to change the degree of dissociation of weak acids and the ratio between the concentrations of 5-ASA molecules and ions and, therefore, the UV spectra. The electronic spectrum of 5-ASA ...

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Regioselective oxidation of recycled cellulosic fibres for enhancement in the mechanical strength of resulting papers

Satapathy,

Patankar

2024

Can J Chem Eng

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The worldwide recycling rate for paper is about 60% and there are ongoing efforts to enhance the recycling rates to 80%. The low strength of recycled paper primarily due to the contaminants in it fetches lower value to the recycled paper in the market and also limits its recyclability. The ways to circumvent the problem of contamination of paper have been addressed by adding additives. However, the use of additives increases the cost of the final recycled paper. Oxidation has been explored as an alternative to enhance the tensile strength of paper in this work as it can be used in existing paper recycling facilities without any modifications. Pulp fibres were collected from an active paper recycling mill and subjected to oxidation at various oxidation levels from 0.25 up to 1.5 mmol/g. It was found that the tensile strength of the paper increased by up to 89% with an increase in oxidation level up to 1 mmol/g and later decreased with a further increase in the oxidation level up to 1.5 mmol/g. The brightness of the paper increased by up to 3% with an increase in oxidation level up to 0.85 mmol/g and then a decrease with further enhancement in the oxidation level. The oxidized samples were also studied with infrared spectroscopy, x‐ray diffraction, electron microscopy, and optical properties to study the behaviour of the resulting material. A ring crush test and corrugating medium test were also performed on the oxidized pulp samples to establish the feasibility of the material for packaging applications.

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Kinetics of oxidation of an arabinogalactan from larch (Larix sibirica L.) in an aqueous medium in the presence of hydrogen peroxide

Cited by 13 publications

References 8 publications

Selective Oxidation of Cellulose—A Multitask Platform with Significant Environmental Impact

Selective Oxidation of Cellulose—A Multitask Platform with Significant Environmental Impact

Arabinogalactan Poly- and Oligosaccharides Modified with 5-Aminosalicylic Acid

Regioselective oxidation of recycled cellulosic fibres for enhancement in the mechanical strength of resulting papers

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