Mechanism of xanthation reaction in viscose process

Gondhalekar, Sachin C.; Pawar, Pravin; Dhumal, Sunil S.; Thakre, Shirish

doi:10.1007/s10570-018-2213-5

Cited by 17 publications

(7 citation statements)

References 20 publications

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“…Therefore, increasing cellulose accessibility requires pores to be opened up, and fibril aggregates and highly ordered regions to be altered (Krässig 1993). The greater the reactivity is, the lower will be the consumption of reagents (CS 2 and NaOH) during cellulose xanthogenation and the easier its dissolution in the aqueous alkaline solution (the so-called dope) (Ibarra et al 2010a;Gondhalekar et al 2019;Arce et al 2020). Thus, high reactivity of dissolving pulps avoids many operational problems during the production of viscose (Chen et al 2016).…”

Section: Reactivity and Accessibilitymentioning

confidence: 99%

Dissolving-grade pulp: a sustainable source for fiber production

Quintana,

Valls,

Roncero

2024

Wood Sci Technol

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The global textile fiber output increased five times from 1975 to 2020. Also, in 2010, the combined demand for man-made and natural fibers was projected to increase by 84% within 20 years. Clothing materials are largely made from cotton or petroleum-based synthetic fibers; both sources, however, have adverse environmental impacts. Thus, cotton requires vast amounts of land, water, fertilizers and pesticides, and synthetic fibers are not biodegradable. This scenario has raised the need for further exploration of cellulose polymers as sustainable sources for the textile industry. Cellulose, the most abundant renewable organic material on earth, is an outstanding polymer that by chemical derivatization or modification can offer a broad range of applications. Dissolving-grade pulp (DGP), which consists of highly pure cellulose, is the most suitable material for manufacturing cellulose derivatives and regenerated fibers. The latter are typically obtained by using the viscose process, which has considerable adverse environmental impacts. Although the textile industry has progressed substantially, further efforts are still needed to make its entire production chain more sustainable. This article provides an in-depth introduction to the potential of fibers with a high cellulose content, known as dissolving-grade pulps. It reviews the properties of DGP, the cooking and purifying methods typically used to obtain it, and the process by which paper-grade pulp can be converted into dissolving-grade pulp. Also, it discusses traditional and recently developed technologies for producing regenerated cellulose fibers. Finally, it examines the potential for recovering cellulose from textile waste as a novel sustainable practice.

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Section: Reactivity and Accessibilitymentioning

confidence: 99%

Dissolving-grade pulp: a sustainable source for fiber production

Quintana,

Valls,

Roncero

2024

Wood Sci Technol

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“…Using the stoichiometric value of CS 2 required for the xanthation phase, 23.5% w CS 2 /w cellulose (Gondhalekar et al, 2019), CS 2 consumption can be calculated by Eq. 4.…”

Section: α-Cellulosementioning

confidence: 99%

Deep Eutectic Solvents as pretreatment for viscose production

Arce

Llano

Mowinckel

et al. 2023

Preprint

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Viscose from dissolving pulp is one of the most used fabrics in the world. However, its production involves a very hazardous compound: CS2. Therefore, reducing its consumption is of utmost importance. In this sense, dissolving pulp can be pretreated, increasing the reactivity of the cellulose and reducing the CS2. Deep eutectic solvents have been used in biomass pretreatment as delignifying agents since their selectivity towards lignin is high. The ones used with lignocellulosic biomass usually comprise a quaternary ammonium and an organic acid. In previous studies, the formed by choline chloride and lactic acid has excellent results among different DES. However, the optimal conditions of the treatment have not been found, which is the aim of this study. This study showed that no harsh conditions are needed to increase reactivity since temperatures below 100 ºC and time below 120 min could be used. Additionally, the study of the influence of the operating conditions led to the mathematical model of reactivity to find the optimal conditions. At the best conditions, reactivity increased to 97.97%, with a CS2 consumption reduction of more than 16%.

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“…CS2 consumption was calculated using Fock reactivity, α-cellulose content and the stoichiometric value required for the xanthation phase (23.5 % w CS2/w cellulose) (Gondhalekar et al 2019). Considering Fock's reactivity as a reaction yield of xanthation and the α-cellulose content of the pulp, the theoretical quantity of fibres (TF) is obtained using equation 2.…”

Section: Cs2 Consumption Calculationmentioning

confidence: 99%

Technical and environmental improvement of the bleaching sequence of dissolving pulp for fibre production

et al. 2020

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Reactivity of dissolving pulp is one of the main parameters to determine its availability to be transformed into viscose. It is related to the use of carbon disulphide (CS2). An industrial sequential totally chlorine free bleaching process is used as case study. It is carried out in two stages: 1) Alkaline extraction (EOP) and 2) peroxide bleaching (PO). In order to assess how to decrease the use of carbon disulphide, several experiments were performed at laboratory scale for the two stages mentioned before by modifying the operating conditions: NaOH and H2O2 dosages, time and temperature. Reactivity using a modified Fock's method and pentosan content was analysed along with quality pulp parameters: α-cellulose, viscosity and lignin content (kappa number). Results showed that reactivity increases through the bleaching process and varies with the chemical dosage in both stages. Pulp obtained at the best conditions had the following characteristics: reactivity, 95.3 %; α-cellulose 91.17 %; intrinsic viscosity, 448 mL/g; kappa number, 1.81 and pentosan content 2.86 %, and as a result, CS2 usage was reduced by 11.88 %. At the best conditions obtained in this work, NaOH dosage in PO stage was reduced to zero and temperature was slightly lower, when compared with industrial operating conditions.

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Mechanism of xanthation reaction in viscose process

Cited by 17 publications

References 20 publications

Dissolving-grade pulp: a sustainable source for fiber production

Dissolving-grade pulp: a sustainable source for fiber production

Deep Eutectic Solvents as pretreatment for viscose production

Technical and environmental improvement of the bleaching sequence of dissolving pulp for fibre production

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