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TECHNOLOGY OF SULPHATE BLEACHING IN THE PROCESSING OF WOOD IN 21ST CENTURY
Abstract
There is a positive trend in global demand for soluble and purified cellulose, including
cellulose used for the production of disposable medical and sanitary and hygienic products. Modern bleaching technology offers two options: elemental chlorine-free (ECF) and chlorine-free (TCF) bleaching. ECF is the dominant bleaching process, but it does not completely eliminate the waste of organochlorine substances and obtain products that fully meet consumer requirements. Improvements are directed to the working conditions of bleaching, especially in the initial stage of bleaching, with the aim of reducing the formation of active chlorine during bleaching, as well as to the combined use of existing and new technologies, including the use of oxygen delignification , enzymatic treatment, improved chlorination, extraction with alkali and others together with the use of oxygen, ozone and hydrogen peroxide.
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Currently, one of the most serious environmental problems is water contamination by oil spills. The use of sorbents is considered one of the most promising approaches to treat this problem .In this study, polyurethane foam (PUF)was used as basal body material and chitin was used as a filler to decrease the cost of the sorbent .The technological parameters of the synthesis process and a heat resistance of the new sorbent were investigated .Three oil-water phases :distilled water, artificial seawater, and artificial river water were tested on the oil adsorption capacity of PPU10M in the ranges of contact time from 5 to 120 min .The results showed that PPU10M had high heat resistance, up to 300 о C and it only lost 5 %of the mass .There was not much of the synthesis process between the combined sorbent and the primitive PUF .At the same time, the PPU10M reached the high oil adsorption capacity in all three oil-water phases; oil adsorption capacity reached 13.78 g/g (distilled water); 14.96 g/g (artificial seawater) and 14.46 g/g (artificial river water .)The removal percentage obtained was about 55-59 .%The study on adsorption kinetic of crude oil for adsorbent PPU10M showed that the pseudo-second-order model was best suitable for the crude oil adsorption process with the correlation coefficient R 2 = 0.998 .The combined sorbent can be used up to 15 cycles while the oil capacity did not change significantly .The amount of regenerated oil reached up to 98 .%Therefore, it showed that PPU10M was a potential oil adsorbent with many advantages for the removal process of oil pollution from water.
The anthropogenic impact on urban rivers is very significant. Industrial enterprises, municipal, and agricultural organizations discharge wastewater directly into the rivers. In the samples of the studied water, certain properties were found. The water in the river is cloudy, brown in color, and in some places has a sharp smell. Extraneous impurities and foam were detected in water. Moreover, various chemicals were found, which are not characteristic to natural waters. The analyzed water is highly polluted as shown by the following chemical indicators, which reported results higher than the Maximum Allowable Concentration: Fe concentration is 24 times higher than standard, Cu is 5 times higher, Mn is 6 times higher, Al is 366 times higher, Hg is 3 times higher, Zn is 4 times higher, NO2 is 2.5 times higher, hydrocarbon pollution is 2.8 times higher, NH4 is 1.9 times higher. Therefore, it is necessary to immediately develop effective methods for monitoring the state of the watercourse, both economic and energetic. To save the sustainable development of the natural system.
Nowadays, oil and its derivatives were considered one of the major energies and they also have been one of the main sources of environmental pollution, especially for water pollution. The tendency in this time of researchers was to find new adsorption, that has high sorption capacity, economical and easy production. By accordance with the present trend, in this study, chitin was used with the dose up to 50% as a filler in the composition of adsorbents basic on polyurethane foam (PUF). The effect of the size (small size: 1-3 mm and large size: 5-10 mm) and the dose (10, 20 and 50%) of filler in the foaming composition to technological parameters of the collected adsorbent, as well as to its absorption capacity were investigated. The results showed that the adsorbents filling with a lower dose of chitin (10 and 20%) were better foaming than the one containing a higher dose of filler. At the same time, the adsorbents containing small chitin also formed the foam better than one filling large size. For 2 types of PUF, the adsorbent from elastic PUF has higher sorption capacity than the semi-elastic adsorbent with the same dose of the filler. For the results of sorption effectivity of the adsorbents presented that the adsorbent with the small size of filler observed greater the absorbency than the one with large size. In which, the elastic adsorbent containing 10% chitin with small size has the highest oil absorption capacity, which reached 13.13 g/g. To compare the sorption capacity of the adsorbent between relation to oil and water, it shown that its oil capacity is significantly higher than the sorption capacity of water.
Previous studies have proved that commercial, off-the-shelf, geodetic-quality Global Positioning System (GPS) receivers can monitor water level using multipath interferometric characteristics from the sea surface. A Lomb–Scargle periodogram (LSP) is typically used to extract the multipath frequency from the signal-to-noise ratio (SNR), which relates to the vertical distance between the antenna phase center and the reflecting surface, and subsequently, estimate sea levels. A wavelet transform can be used to analyze the time series with a nonstationary power at different frequencies, as can be the case for multipath signals. In addition, wavelet transform analysis estimates the local energy and instantaneous frequency of the signal at every epoch, which is beneficial for water-level estimation. Therefore, we attempt to extract the instantaneous multipath frequency using wavelet transform analysis for water leveling with a geodetic GPS receiver. This study analyzed SNR data of GPS L1C from three test sites: the Kachemak Bay site PBAY (AK, USA), the Friday Harbor site SC02 (WA, USA), and the Brest Harbor site BRST (France). These sites are located in different multipath environments, from a rural coastal area to a busy harbor, and they experience different tidal regimes. The results show that the wavelet analysis has potential for the retrieval of sea level heights. For measurement site PBAY the comparison of the results obtained by the wavelet and LSP analysis yield consistency within a few percent. At the other two sites, SC02 and BRST, the agreement is significantly lower.
This work describes the effect of the hot chlorine dioxide delignification (DHT) on the properties of bagasse fiber and the formation of AOX. The bagasse pulp was subjected to both DHT and normal temperature chlorine dioxide delignification (D0), and the AOX contents in the effluent were determined respectively. The GC–MS results showed that the main components of the D0 stage wastewater were chlorinated hydrocarbons and chlorinated diphenyls. In contrast, those AOXs in the DHT stage wastewater were very few. The GC–MS, ATR-FTIR, and XPS results showed the DHT process is more effective in the removal of the residual phenolic lignin and the hemicellulose-linked HexA compared with D0. Furthermore, in comparison, the AOX content could be reduced by 50% with DHT. The fully bleached pulp obtained via DHTEpD process has a higher brightness than that obtained by D0EpD, which provides a reliable theoretical basis for industrial application. © 2018 Springer Science+Business Media B.V., part of Springer Nature
Sustainability education (SE) is included in school curricula to integrate the principles, values, and practices of sustainable development (SD) into all education. This study investigates lower secondary school subject teachers as educators for sustainability. A survey was used to study the perceptions of 442 subject teachers from 49 schools in Finland. There were significant differences between the subject teachers’ perceptions of their SE competence, and the frequency with which they used different dimensions of SE (ecological, economic, social, well-being, cultural) in their teaching varied. Teachers’ age had a small effect, but gender, school, and its residential location were nonsignificant factors. Teachers could be roughly classified into three different subgroups according to their perceptions of the role of SE in their teaching; those who considered three SE dimensions rather often and used holistic sustainability approaches in their teaching (biology, geography, history); those who considered two or three dimensions often but were not active in holistic teaching (mother tongue, religion, visual arts, crafts, music, physical and health education, and home economics) and those who used one SE dimension or consider only one holistic approach in their teaching (mathematics, physics, chemistry and language). Subject teachers’ awareness of their SE competence is important to encourage them to plan and implement discipline-based and interdisciplinary SE in their teaching. The specific SE expertise of subject teachers should be taken into account in teacher training and education.
The widespread adoption of genetically engineered (GE) crops has clearly led to changes in pesticide use, but the nature and extent of these impacts remain open questions. We study this issue with a unique, large, and representative sample of plot-level choices made by U.S. maize and soybean farmers from 1998 to 2011. On average, adopters of GE glyphosate-tolerant (GT) soybeans used 28% (0.30 kg/ha) more herbicide than nonadopters, adopters of GT maize used 1.2% (0.03 kg/ha) less herbicide than nonadopters, and adopters of GE insect-resistant (IR) maize used 11.2% (0.013 kg/ha) less insecticide than nonadopters. When pesticides are weighted by the environmental impact quotient, however, we find that (relative to nonadopters) GE adopters used about the same amount of soybean herbicides, 9.8% less of maize herbicides, and 10.4% less of maize insecticides. In addition, the results indicate that the difference in pesticide use between GE and non-GE adopters has changed significantly over time. For both soybean and maize, GT adopters used increasingly more herbicides relative to nonadopters, whereas adopters of IR maize used increasingly less insecticides. The estimated pattern of change in herbicide use over time is consistent with the emergence of glyphosate weed resistance.
The pulp and paper industry is highly dependent on forest and water resources. It has more concerns on fair utilization of these resources and their conservation for its further expansion. Present study emphasizes on the use of rice straw (agro waste) in papermaking to protect wood based resources. It further deals with ozone bleaching (Z) prior to elemental chlorine free bleaching that proved to be significant in terms of reducing the effluent load specially the reduction in toxic, recalcitrant and carcinogenic compounds. Z based sequences resulted in pulp brightness of ∼85% that was 3.6% higher than the elemental chlorine free bleaching. Bleached pulps of Z based sequences were found to be having better strength properties than elemental chlorine based sequence and thus may be adopted as improved bleaching technology. The analysis of handsheets prepared after pulp bleaching was performed using X-Ray diffraction, ATR-FTIR and SEM. Incorporating ozone stage resulted in marked reduction of 58% and 63% in total solids in bleaching wastewater. Reduction of more than 80% in BOD, COD and adsorbable organic halides was achieved in Z based bleaching in comparison to chlorine bleaching. The amount of chlorophenols, guaiacols, catechols, vanillins and syringols became negligible (approx. 90% reduction) in effluents of Z based bleaching sequences. The chlorine dioxide followed by peroxide bleaching after Z stage was found to be the most promising to reduce the effluent load.
Water samples from streams in suburban region of new builds were analyzed in order to suggest methods and parameters for pollution monitoring. Concentrations of total nitrogen (TN) varied from 0.6 to 9.0 mg/L, ammonium - from 0 to 6.8 mg/L, total organic carbon (TOC) from 8.3 to 21.1 mg/L. Electric conductivity (EC) varied from 80 to 640 mkSm/cm, optical density at 254 nm - from 0.41 to 1.07. Increased concentrations of TN and ammonium at several sampling sites confirmed wastewater discharge from dwelling area. Polluted waters also showed higher values of electric conductivity and molar fractions for sodium and chloride ions, lower values of optical density (in range 230 - 420 nm) and TOC. Fluorescence intensity (I) was measured at excitation wavelength 230 and 270 nm, emission wavelengths 300-350 nm (protein-like fluorescence, present in wastewaters), 420 nm (humic-like fluorescence, present in natural and waste waters). Character of correlation between fluorescence intensity and TN (marker of pollution) and TOC depended on wavelengths, fluorescence signal correction and dilution of sample. Only I at 230 nm excitation and 350 nm emission for 10-fold diluted sample of water could be recommended for water monitoring. EC can be used as additional parameter in studied streams. © 2017 Il'ina Kh.V.,Gavrilova N.M.,Bondarenko E.A.,Andrianova M.Ju.,Chusov A.N.