Cellulose extraction method

The first recommended soil method for oxime carbamates is the method of Honing et al. by HPLC/MS. The LOQ of the method, specifically for aldicarb, methomyl, and oxamyl, is 0.05mgkg. Soil (lOg) is Soxhlet extracted for 16h with acetone-dichloromethane (1 1) using double-thickness cellulose extraction thimbles (80 X 22-mm i.d.). Prior to extraction, the Soxhlet system and the thimbles are cleaned for 14 h by refluxing with methanol. The extracts are removed and concentrated nearly to dryness in a rotary evaporator operating at 35 °C evaporation to dryness... 

With tanning extracts adulterated with cellulosic extracts, the indirect method does not, however, give reliable results, since cellulosic extracts contain non-tannins which are fixed by the hide powder. In such a case the tannin should be determined by the direct method, since these non-tannins have no appreciable action on permanganate the difference between the results of the two methods will give an approximate indication of the extent of the adulteration, if this is at all marked. 

As regards extracts, their composition varies greatly according both to the methods of preparation and purification and to the degree of concentration. With these the possibility of adulteration, especially with glucose, molasses, cellulose extracts and mineral salts, is to be considered. Addition of sulphurous anhydride or sulphites is allowed, for either clarification or preservation of the extract the proportion of total sulphurous acid may reach and even exceed 2%. 

Treated papers should maintain at a pH in the range 7 and 8.5. The pH should not be higher than 8.5 to prevent alkaline hydrolysis of cellulose. The acidity or alkalinity may be determined as the amount of water-soluble acidity or as the hydrogen ion concentration (pH) of the paper extract. The pH is more indicative of the stability of paper than is the total acidity. The pH can be determined by either a hot or cold extraction method. In the cold extraction method,... 

This is a classical extraction method in which samples are placed in cellulose thimbles covered with cotton-wool, as shown in Figure 2.16. A certain quantity of solvent is added into the system and is heated to an appropriate temperature which allows the solvent to boil. Then, the solvent vapor condenses in a condenser and drops of solvent fall down onto solid sample particles. Once the side-vessel is full, the solvent runs back to the bottom flask. This process is repeated for several hours until adequate recovery of the analytes is obtained. 

Abstract This chapter deals with the structure, properties and applications of natural fibres. Extraction methods of Natural Fibres from different sources have been discussed in detail. Natural fibres have the special advantage of high specific strength and sustainability, which make them ideal candidates for reinforcement in various polymeric matrices. Natural fibres find application in various fields like construction, automobile industry and also in soil conservation. It is the main source of cellulose, an eminent representative of nanomaterial. Extractions of cellulose from plant-based fibres are discussed in detail. Various mediods used for characterization of cellulose nanofibres and advantages of these nanofibres have also been dealt with. 

Sisal varies in quality. The large variations in its chemical compositions are because of its different sources, age, extraction methods, etc. [23]. Eor example, Wilson [13] indicated that sisal fiber contains 78% cellulose, 8% lignin, 10% hemicelluloses, 2% waxes, and about 1% ash by weight, whereas Rowell et al. [24] found that sisal contains 43-56% cellulose, 7-9% lignin, 21-24% pentosan, and 0.6-1.1% ash. The work carried out by Chand and Hashmi [25] showed that the cellulose and lignin contents of sisal vary from 49.62 to 60.95% and 3.75 to 4.40%, respectively, depending on the age of the plant. 

However, there are some methods for extraction of cellulose from plants. Han and Rowell s (1996) method describes a procedure for extraction of holocellulose, hemicelluloses, cellulose and lignin [18]. The method consists of four principle steps (1) preparation of sample (grinding of the wood), (2) removal of extractives, (3) preparation of holocellulose (removal of lignin), (4) preparation of a-cellulose (removal of hemicellulose). Several other procedures for a-cellulose extraction from wood samples have already been described during the last decades. Older methods used benzene-methanol instead of toluene-ethanol as organic solvent for the second step. Toluene-ethanol works as well as benzene-methanol mixture, and reduces health risks associated with the use of benzene and methanol. 

In addition, Borella et al. (2004) presented a method that is quite similar to Han and Rowell s (1996) method. They foxmd that fine milling the samples is very important for (1) avoiding sample inhomogeneity leading to increased measurement uncertainty, and (2) permitting complete a-cellulose extraction. 

As shown in Figure 21.7, at first, kenaf fiber was prepared from the bast part of kenaf stems. The cellulose extraction of kenaf fiber was then carried out using the Han and Rowell method [18]. Since cellulose is very hygroscopic material, the obtained cellulose was packed imder vacuum packaging. Cellulose and the other materials were blended in the internal mixer and were then compressed using the hot press machine to be converted into sheet form. Finally, the sheet forms of treatments were evaluated by standard tests [21]. 

The source of nanofiber is varied either from animal or plant that contains different amount of chemical composition. Thus, in nanofiber production, different natural fibers need to imdergo several chemical and physical treatments. In addition, every extraction method gave different results in term of quality and yields, hence other techniques of cellulose nanofiber production need to be explored. Furthermore, as found in previous research, combination of chemical, enzymatic, and physical... 

In some cases the isolation of cellulose micro/nanofibrils involves enzymatic pretreatment followed by mechanical treatments [22,23]. The morphology and aspect ratio of the extracted nanofibers may vary depending upon the raw materials and extraction techniques [24]. Examples of various cellulose nanofiber extraction methods, including microfibrillar cellulose (MFC) are shown in Table 5.1. 

Nanocellulose can broadly be defined as a set of particles having at least one dimension in nanoscale obtained by different mechanical/chemical, or only chemical, or acid-hydrolysis methods. According to a survey of the literature, there is no standardized nomenclature for cellulose-based nanoparticles, while various terms have been used to describe a particular set of cellulose nanoparticles. Because of inconsistency in use of these terms, there are some particle types depending on source materials of cellulose and method of extraction. However, depending on their aspect ratio, nanocelluloses have already been characterized with different terms like microfibrillated cellulose (MFC-diameter 10-100 nm) [34], nanofibrillated cellulose (NFC-diameter 4-20 nm) [35], CNCs (CNCs-diameter 3-5 nm) [34, 36], tunicate CNCs (t-CNCs-diameter 20 nm) [34, 37], algae cellulose particles (AC-diameter 20 nm) [38,39], bacterial cellulose particles (BC-diameter 6-50 nm) [40, 41]. It can commonly be called "nanocellulose,"... 

Microcrystalline cellulose extraction involving pre-treatment with soda anthraquinone method, and bleached with ozone and peroxide, later hydrolysis with 2.5 MHCl at 105°C for 15 min. Wanrosh et al. (2011)... 

Incorporation of maleic anhydride and styrene into cellulose produces a symmetrical amphiphilic graft copolymer. Poly(styrene-a/ acrylonitrile) has been grafted onto cellulose in the presence of zinc chloride [54]. Similarly poly(styrene-ran-maleic anhydride) has been grafted onto cellulose acetate, obtaining up to 70% graft yield [55]. Recently binary mixtures of styrene and maleic anhydride has been graft copolymerized onto cellulose extracted from Pinus needles by using a simultaneous irradiation method [56]. 

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