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Sourcing and Re-Sourcing End-of-Use Textiles
Published in Judith S. Weis, Francesca De Falco, Mariacristina Cocca, Polluting Textiles, 2022
Wolfgang Ipsmiller, Andreas Bartl
In literature, several attempts can be found distinctively concerning the disintegration of cellulose, mainly from cotton fibres from pure cotton fabric or blended fabrics also containing cotton as well as lignocellulosic biomass. There are efforts to use methods to treat the latter – although substrates are different, yet all contain cellulose – for fibrous waste treatment. The processes already discussed generally use catalytic procedures (Hou, Ling, Shi, & Yan, 2019) and/or thermo-baric steam treatment or ‘steam explosion’, hitherto known mainly from bio-refinery applications (Pavlov, Denisova, Makarova, Budaeva, & Sakovich, 2015; Ruiz et al., 2020), where the cellulose polymer structure is maintained for the most part, but the external structure is made void. This leads to a powder-like cellulose polymer substance known as microcrystalline cellulose that is reported to be used in the pharmaceutical industry (Uesu, Pineda, & Hechenleitner, 2000).
Cellulose-Based NanoBioMaterials
Published in Bhupinder Singh, Om Prakash Katare, Eliana B. Souto, NanoAgroceuticals & NanoPhytoChemicals, 2018
Michael Ioelovich, Sumant Saini, Teenu Sharma, Bhupinder Singh
Microcrystalline cellulose (MCC) is produced by depolymerization of cotton or wood cellulose with dilute (1.5–2.5 M) solutions of mineral acids at elevated temperatures to achieve a low constant DP of 120–300 (Nada et al., 2009; Ioelovich, 2016a, 2018b). For example, pieces of pure cellulose are put in a reactor, which is filled with a 10-fold amount of 10% hydrochloric acid. The reactor is closed, and the reaction system is heated at 100°C for 1 h and then cooled. The hydrolyzed cellulose is discharged, separated from the acidic phase by filtration or centrifugation, washed, and concentrated to 30%–40% solid content. The wet product is bulk-dried and disaggregated to rod-like MCC particles with a length of 50–100 μm and a diameter of 10–30 μm (Figure 11.4a). Another technology is that the wet product is dispersed in water and spray-dried to obtain elliptical MCC particles with average diameter from 50 to 200 μm, as aggregates of rod-like MCC particles (Figure 11.4b).
The Role of Polymers in Solid Oral Dosage Forms
Published in Ijeoma F. Uchegbu, Andreas G. Schätzlein, Polymers in Drug Delivery, 2006
Richard A. Kendall, Abdul W. Basit
Polymers have been used for many years as excipients in conventional immediate-release oral dosage forms, either to aid in the manufacturing process or to protect the drug from degradation upon storage. The judicious choice of excipients is also necessary to enhance the in vivo behavior of the dosage form. Disintegration and subsequent drug release and dissolution and, therefore, absorption and bioavailability (i.e., pharmacokinetics) can, to a certain extent, be controlled by the choice of excipients. Microcrystalline cellulose is often used as an alternative to carbohydrates as diluents in tablet formulations of highly potent low-dose drugs. Starch and cellulose are used as disintegrants in tablet formulations, which swell on contact with water, resulting in the tablet “bursting,” increasing the exposed surface area of the drug, and improving the dissolution characteristics of a formulation. Polymers including polyvinyl-pyrrolidone and hydroxypropyl methylcellulose (HPMC) also find uses as binders that aid the formation of granules that improve the flow and compaction properties of tablet formulations prior to tableting. Occasionally, dosage forms must be coated with a “nonfunctional” polymeric film coating in order to protect a drug from degradation, mask the taste of an unpalatable drug or excipient, or improve the visual elegance of the formulation, without affecting the drug release rate [8,9]. Low-viscosity grades of HPMC or polyvinyl-pyrrolidone are suitable for such applications.
Varronia verbenacea and Achyrocline satureioides essential oils in granules and microparticles: Stability and in vitro release studies
Published in Drying Technology, 2021
J. C. K. Monteiro Filho, R. A. F. Rodrigues
A reduction in α-humulene and trans-caryophyllene was also observed after 60 days in all samples. In addition to the low solid concentration of 14% verified in the formulations, which induces expulsion of the core material as shown by Fernandes et al.,[102] the results obtained by Garcia et al.[76] showed that mixtures presenting higher microcrystalline cellulose proportions could lead to a decreased retention rate since the hydrophobic nature of microcrystalline cellulose promotes the expulsion of its contents. One condition that could have enhanced essential oil retention is the increased lactose in the formulation since lactose can form a glassy layer on the outer side of the powder in the microcapsule, which would entrap the core material more efficiently[103] and exert less of a hydrophobic effect than microcrystalline cellulose does.[92]
Mesoporous CeO2 Catalyst Synthesized by Using Cellulose as Template for the Ozonation of Phenol
Published in Ozone: Science & Engineering, 2019
Lan-He Zhang, Jing Zhou, Zheng-Qian Liu, Jing-Bo Guo
Various synthetic nano-CeO2 methods have been reported, including hydrothermal method, precipitation, liquid evaporation method, sol-gel method, and template preparation (Chen et al. 2016; Wu et al. 2004; Fisher et al. 2016). Diverse morphologies CeO2 could be obtained by adding different surfactants or modifiers, which has a tremendous impact on its performance. The rod, wire, and fibrous CeO2 with large specific surface area and narrow pore size could be used to improve the activity and oxygen storage ability of the catalyst (Bai et al. 2016). The template preparation is one of the most promising methods to synthesize the nano-CeO2 with strong stability and regular structure (Mu et al. 2015; Lolli et al. 2016). Solsona et al. (2017) prepared porous ceria materials using different templates (urea, activated carbon, and polymer) and applied in removal of VOCs. In the past, many macromolecule organics, such as polyvinylpyrrolidone (Si et al. 2006) and cetyl trimethyl ammonium bromide (Hua and Soucek 2007), had been used as template agent, but most of these templates are so expensive that they cannot be widely used in the actual production. Some researchers had utilized the bio-renewable cellulose with hydroxyl groups as the template, since nucleation could be formed between the hydroxyl groups of the cellulose and the metal precursor, which can avoid the growth and aggregation of the metal precursor (Huang and Kunitake 2003). Santra, Joarder, and Sarkar (2014) synthesized cerium loading cellulose nanocomposite via sol-gel formation technique for fluoride adsorption, and almost 90% of adsorbed fluoride could be eluted. Miao et al. (2006) dispersed cellulose in the ionic liquid solution and titanium tetrabutyloxide as the Ti precursor to prepare mesoporous TiO2 films with 10 ~ 20 nm in crystal size. The microcrystalline cellulose (MCC), as the product of cellulose hydrolysis, possessed special properties such as lower degree of polymerization and higher surface areas (Liu, Tao, and Zhang 2012). However, reports using MCC as template to synthesize CeO2 in the heterogeneous catalytic processes were rare.
An overview of cotton and polyester, and their blended waste textile valorisation to value-added products: A circular economy approach – research trends, opportunities and challenges
Published in Critical Reviews in Environmental Science and Technology, 2022
Karpagam Subramanian, Manas Kumar Sarkar, Huaimin Wang, Zi-Hao Qin, Shauhrat S. Chopra, Mushan Jin, Vinod Kumar, Chao Chen, Chi-Wing Tsang, Carol Sze Ki Lin
Valorization of textile waste into higher value-added products has gained increasing interest from researchers striving for sustainable energy supplies and effective textile waste management. (Johnson et al., 2020) compared different valorization processes and products from cotton waste to their virgin alternative products, shedding light on potential new markets for products from waste cotton that do not compete with virgin cotton applications. Cotton and other textile wastes have been repurposed for value-added products such as composites, microbial fuel cells, potassium-ion exchange, environmental applications of biochar (catalyst/adsorbent), sound absorbers, thermal insulators and electromagnetic interference (EMI) shields (Shirvanimoghaddam et al., 2020). Valorization of waste jeans to recover cotton fiber and polyester showed economic returns up to $1,629/ton and reduction in carbon footprint by 1,440 kg of CO2-eq/t of waste (Yousef et al., 2020). The cotton part of waste jeans can be valorized to produce biogas, bioethanol and sugars (Hasanzadeh et al., 2018; Nikolic et al., 2017). (Haslinger et al., 2019) demonstrated the chemical upcycling of dyed pre- and postconsumer cotton waste to new man-made cellulosic fibers retaining the color and with better properties than commercial viscose or lyocell. High-quality activated carbon that can be used for various adsorbent applications was produced from cotton biomass waste materials (Sartova et al., 2019). Microcrystalline cellulose was prepared from waste cotton fabrics by catalytic hydrolysis of phosphotungstic acid (H3PW12O40) (Hou et al., 2019; Shi et al., 2018). Industrial cotton wastes like cotton oil, cotton silver waste, short staple cotton waste and cotton gin waste were valorized to produce cellulose nanocrystals (CNCs), which have promising applications in biomedicine and hydrogels (Maciel et al., 2019). Spherical CNCs extracted from viscose fiber waste are considered an effective value-added alternative with high potential as Pickering emulsion stabilizers in ‘green food’ and nanofillers in high-performance composites (Ye et al., 2018). Wastes from colored cotton fabrics are considered promising raw materials for the production of regenerated cellulose fibers (Ma et al., 2020). Utilization of textile waste as an energy feedstock in the form of biochar was explored, and it was found that cotton and cotton-blended wastes can potentially be used to produce a solid fuel as a substitute fuel in coal/waste co-firing systems (Hanoğlu et al., 2019). Diverse mixed fiber wastes are processed and used as composite blend mixtures for textile fiber-reinforced composite (TRFC), an alternative low-carbon, nontoxic material that can be used in high-end building applications (Echeverria et al., 2019). Our research group has successfully demonstrated recovery of glucose sirup and polyester fiber from cotton and polyester waste fabric (Li et al., 2019b). Cotton/polyester blended wastes are also used as low-cost feedstock for producing fungal cellulase through SSF (Hu et al., 2018; Sahu & Pramanik, 2018).