Research Articles

The composition and properties of the products of fast pyrolysis of hardwood, obtained in a two-chamber (drying and pyrolytic) ablation type reactor in the temperature range 450-600ºС, were investigated. It has been found that, upon the additional drying of wood at 200ºС and subsequent pyrolysis, the quality of bio-oil is improved owing to the decrease in the amount of water and acids. It has been shown that the increase of the drying temperature to 240ºС decreases the yield of the main product. Optimum parameters of the drying conditions and the temperature of the pyrolysis of wood, at which the bio-oil yield exceeds 60% and its calorific value makes up 17-20 МJ/kg, have been determined.

An experimental study was conducted to determine the abrasive wear behaviour of different weight percentage bamboo powder filled polyester composites under the multipass mode. The effect of bamboo powder concentration and sliding distance on the weight loss of composites has been analyzed. Worn surface have been analyzed to observe the mechanism of wear. The weight loss depends on bamboo powder concentration. The weight loss decreases with the increase of sliding distance. Samples having 20 weight percentage (wt%) of bamboo powder show the maximum weight loss during abrasion.

Porous cellulose beads were prepared by solubilizing cellulose in sodium hydroxide/urea/sulfourea aqueous solution and then solidifying liquid beads in hydrochloric acid. Scanning electron microscopy (SEM) was used to characterize the morphologies of surface, cross section, and wall structures of the porous cellulose beads, which are folded and porous. The surface acid-base properties of porous cellulose beads were characterized in detail by inverse gas chromatography (IGC). The Lewis basic number Kb was found to be 0.854, which is indicative of a Lewis basic polymeric material. With the discussion of the results of SEM and IGC, a conclusion can be drawn that the porous cellulose beads showed a good ability of adsorbing the smoking tar of cigarettes.

The hydroxymethylation of alkali lignin with formaldehyde in alkaline solution was studied. The influence of reaction conditions of the hydroxymethylation of alkali lignin was followed by modifying the temperature, time, and the ratios of NaOH to lignin and CH2O to lignin. Three different types of alkali lignin were utilized. The reaction was followed by total consumption of formaldehyde, and the resulting products were characterized through FTIR-spectra, thermogravimetry analysis, ash and moisture contents, as well as by the amounts of OH groups.

Oxidation of TMP fibers was compared at 298 K with molecular oxygen, in the presence of either [Co(salen)] in methanol or [Co(sulphosalen)] in water. Electron paramagnetic resonance (EPR) spectroscopy made it possible to reveal and quantify the formation of phenoxy cobalt radicals in the former case and of phenoxy radicals in the latter. These radicals reached the same concentration after 60 min from the onset of reaction. Fiber integrity was more preserved after oxidation in water than in methanol, as assessed by heteronuclear single quantum coherence - nuclear magnetic resonance (2D-HSQC-NMR) spectroscopy, nuclear magnetic resonance spectroscopy of carbon (13C-NMR), and Gel Permeation Chromatography (GPC). These results suggest that efficient radical formation on fibers can be achieved also with water-soluble catalysts. Thus, it is proposed that treatment with molecular oxygen in the presence of [Co(sulphosalen)] in water represents a promising way to approach an environmentally sustainable radicalization of fibers, without heavy modification of the lignin structure.

Sorption of carboxymethyl cellulose (CMC) on the fiber surface was applied during oxygen delignification to enhance the strength properties of softwood kraft pulp. Unlike many previous efforts, the focus was not set on the improvement of selectivity of oxygen delignification, i.e. retaining stable viscosity vs. decreasing kappa number. Instead, without an improved selectivity, handsheets from CMC-treated fibers exhibited a 15% improvement in tensile index and 25% improvement in tear index after a full bleaching sequence in comparison to the untreated reference pulp. Since it is demonstrated that the CMC addition can be incorporated as an integral step in the fiberline process, the method offers an effortless and viable option to produce pulp resulting in stronger paper products.

Graft copolymerization of acrylamide monomer onto cellulose, using ceric ammonium nitrate as initiator, was investigated. Water and metal ions sorption by this grafted cellulose were estimated. The conditions of grafting, e.g. grafting time, dose of initiator, ratio of monomer to cellulose, acid concentration and liquor ratio, were evaluated. The different properties as graft and graft efficiency percentage, as well as polymerization percent, have been determined. Grafted cellulose has been characterized by FTIR and swelling studies. Sorption of different metal ions in the mixture, e.g. Cu, Cr, Ni, and Pb, by grafted cellulose was investigated. The effect of hydrolysis of grafted cellulose by using sodium hydroxide on its swelling properties and metal ions sorption was also investigated. Hydrolysis increases the sorption affinity of grafted cellulose toward water and metal ions .

The isolation of non-cellulosic polysaccharides from almond shells (AS) and their solid residue (ASR) after autohydrolysis was investigated using a two-step alkaline extraction without and in combination with short ultrasonic treatment. The obtained polysaccharide preparations were characterized by yield, chemical composition, and structural features, and the antioxidant activity of the water-soluble preparations tested. The results showed that the use of ultrasound at a reduced extraction time of 10 min as compared to 60 min of the classical procedure, with a 5% NaOH solution, resulted in the greatest yield of hemicelluloses. The AOA of their water-soluble portion ranged between 48 and 80%, indicating the antioxidant potential of these materials. The xylan polymers isolated from both AS and ASR might serve as biopolymer sources in native form or after targeted modification for production of value-added substances and polysaccharide-based antioxidants applicable in food, cosmetics, and other areas.

Butyl and hexyl amides of pectate with various amidation degrees were prepared from citrus pectin by means of alkylamidation of methyl-esterified pectins, followed by the total alkaline pectin methyl esters hydrolysis. These water soluble derivatives were characterized chem-ically as well as by elementary analysis and FT-IR spectroscopy. All prepared pectate amides exhibited the excellent emulsifying efficiency, and pectate hexyl amide also the ability to form stable foam. As the results of the study on the effect of pectin with DE 66% on the function of small intestine in pectin fed rats, the increase of specific activity of alkaline phosphatase, maltase, and aminopeptidase and the decrease of food utilization was demonstrated. The pectin derivatives might serve as emulsifiers and foaming additives in food production and other areas as well as nutraceuticals for obesity treatment.

Tert-butyldimethylsilyl cellulose with a degree of substitution (DS) of up to 2 could be obtained by homogeneous conversion of the biopolymer with tert-butyldimethylchlorosilane in N,N-dimethyl acetamide/LiCl in the presence of imidazole. The cellulose derivatives were characterized in detail by means of two-dimensional NMR spectroscopic techniques including subsequent derivatization of the original polymer by consecu-tive methylation-desilyation-acetylation. The very well resolved NMR spectra indicate that, dependent on the reaction temperature, 2,6-di-O-tert-butyldimethylsilyl moieties are the main repeating units. 3,6-di-O- and 6-mono-O functionalized repeating units were identified in very small amounts if the reaction is carried out at room temperature. Additionally, 2,3,6-tri-O-silylated functions appear if reaction is carried out at temperature of 100°C. Thus, a novel path for regioselective protection of position 2 and 6 for cellulose was established.