Hydrogen peroxide and supercritical carbon dioxide: a new bleaching stage for Eucalyptus kraft-O(2) pulps

Kraft pulp is currently bleached largely by the elemental chlorine free (ECF) technology with oxygen, chlorine dioxide, and hydrogen as active agents. This technology brought about significant environmental improvements in relation to standard processes based on chlorine gas and hypochlorite, but there is still need for further improvements. This study presents a novel environmentally friendly bleaching stage - the so-called `hydrogen peroxide in supercritical carbon dioxide`, P((SC-CO2)) - that can be adapted to current ECF bleaching processes, with preference in cases where hydrogen peroxide is already used. In this study, the P((SC-CO2)) stage was evaluated as a replacement to the last peroxide stage of the D(EP)DP bleaching sequence and to the first peroxide stage of the D(EP)DP sequence, for an oxygen delignified eucalypt kraft-O(2) pulp. The P((SC-CO2)) stage was run with 0.5% hydrogen peroxide, at 15% consistency, 70 degrees C, and 73 bar. The reaction time was 30 min. The performances of regular P stages and the new P((SC-CO2)) stage were compared. Promising results were observed with the DEP((SC-CO2))DP sequence; the P((SC-CO2)) decreased kappa number from 2.7 to 2.1, and the hexenuronic acid groups from 17.0 to 12.4 mmol kg(-1). The P((SC-CO2)) stage showed poor performance when applied in the D(EP)DP((SC-CO2)) sequence. It is concluded that the process presents potential but requires further optimization to improve selectivity and efficiency.

Determination of carbaryl in tomato ""in natura"" using an amperometric biosensor based on the inhibition of acetylcholinesterase activity

This work reports the utilization of two methodologies for carbaryl determination in tomatoes. The measurements were carried out using an amperometric biosensor technique based on the inhibition of acetylcholinesterase activity due to carbaryl adsorption and a HPLC procedure. The electrochemical experiments were performed in 0.1 mol L-1 phosphate buffer solutions at pH 7.4 with an incubation time of 8 min. The analytical curve obtained in pure solutions showed excellent linearity in the 5.0 x 10(-5) to 75 x 10(-5) mol L-1 range, with the limit of detection at 0.4 x 10(-3) gL(-1). The application of such a methodology in tomato samples involved solely liquidising the samples, which were spiked with 6.0 x 10(-6) and 5.0 x 10(-5) mol L-1 carbaryl. Recovery in such samples presented values of 99.0 and 92.4%, respectively. In order to obtain a comparison, HPLC experiments were also conducted under similar conditions. However, the tomato samples have to be manipulated by an extraction procedure (MSPD), which yielded much lower recovery values (78.3 and 84.8%, respectively). On the other hand, the detection limit obtained was much lower than that for the biosensor, i.e., 3.2 x 10(-6) g L-1. Finally, the biosensor methodology was employed to analyze carbaryl directly inside the tomato, without any previous manipulation. In this case, the biosensor was immersed in the tomato pulp, which had previously been spiked with the pesticide for 8 min, removed and inserted in the electrochemical cell. A recovery of 83.4% was obtained, showing very low interference of the matrix constituents. (C) 2007 Elsevier B.V. All rights reserved.

Surface esterification of cellulose fibres: Processing and characterisation of low-density polyethylene/cellulose fibres composites

Low-density polyethylene was filled with cellulose fibres from sugar cane bagasse obtained from organosolv/supercritical carbon dioxide pulping process. The fibres were also used after chemical modification with octadecanoyl and dodecanoyl chloride acids. The morphology, thermal properties, mechanical properties in both the linear and nonlinear range, and the water absorption behaviour of ensuing composites were tested. The evidence of occurrence of the chemical modification was checked by X-ray photoelectron spectrometry. The degree of polymerisation of the fibres and their intrinsic properties (zero tensile strength) were determined. It clearly appeared that the surface chemical modification of cellulose fibres resulted in improved interfacial adhesion with the matrix and higher dispersion level. However, composites did not show improved mechanical performances when compared to unmodified fibres. This surprising result was ascribed to the strong lowering of the degree of polymerisation of cellulose fibres (as confirmed by the drastic decrease of their zero tensile strength) after chemical treatment despite the mild conditions used. (c) 2007 Elsevier Ltd. All rights reserved.

Physical Vapor Deposited Thin Films of Lignins Extracted from Sugar Cane Bagasse: Morphology, Electrical Properties, and Sensing Applications

The concern related to the environmental degradation and to the exhaustion of natural resources has induced the research on biodegradable materials obtained from renewable sources, which involves fundamental properties and general application. In this context, we have fabricated thin films of lignins, which were extracted from sugar cane bagasse via modified organosolv process using ethanol as organic solvent. The films were made using the vacuum thermal evaporation technique (PVD, physical vapor deposition) grown up to 120 nm. The main objective was to explore basic properties such as electrical and surface morphology and the sensing performance of these lignins as transducers. The PVD film growth was monitored via ultraviolet-visible (UV-vis) absorption spectroscopy and quartz crystal microbalance, revealing a linear relationship between absorbance and film thickness. The 120 nm lignin PVD film morphology presented small aggregates spread all over the film surface on the nanometer scale (atomic force microscopy, AFM) and homogeneous on the micrometer scale (optical microscopy). The PVD films were deposited onto Au interdigitated electrode (IDE) for both electrical characterization and sensing experiments. In the case of electrical characterization, current versus voltage (I vs V) dc measurements were carried out for the Au IDE coated with 120 nm lignin PVD film, leading to a conductivity of 3.6 x 10(-10) S/m. Using impedance spectroscopy, also for the Au IDE coated with the 120 nm lignin PVD film, dielectric constant of 8.0, tan delta of 3.9 x 10(-3)) and conductivity of 1.75 x 10(-9) S/m were calculated at 1 kHz. As a proof-of-principle, the application of these lignins as transducers in sensing devices was monitored by both impedance spectroscopy (capacitance vs frequency) and I versus time dc measurements toward aniline vapor (saturated atmosphere). The electrical responses showed that the sensing units are sensible to aniline vapor with the process being reversible. AFM images conducted directly onto the sensing units (Au IDE coated with 120 nm lignin PVD film) before and after the sensing experiments showed a decrease in the PVD film roughness from 5.8 to 3.2 nm after exposing to aniline.

Agro-Based Biocomposites for Industrial Applications

Leaf fibers are fibers that run lengthwise through the leaves of most monocotyledonous plants such as pineapple, banana, etc. Pineapple (Ananas comosus) and Banana (Musa indica) are emerging fiber having a very large potential to be used for composite materials. Over 150,000 ha of pineapple and over 100,000 ha of banana plantations are available in Brazil for the fruit production and enormous amount of agricultural waste is produced. This residual waste represents one of the single largest sources of cellulose fibers available at almost no cost. The potential consumers for this fiber are pulp and paper, chemical feedstock, textiles and composites for the automotive, furniture and civil construction industry.

Evaluation of the antioxidant activity of passion fruit (Passiflora edulis and Passiflora alata) extracts on stimulated neutrophils and myeloperoxidase activity assays

The antioxidant activity of methanol extracts from Passiflora edulis and Passiflora alata pulp, and P. edulis rinds, healthy or infected with the passion fruit woodiness virus (PWV), was investigated using the oxidant activities of the neutrophil and the neutrophil granule enzyme myeloperoxidase (MPO), both playing key roles in inflammation. The reactive oxygen species produced by stimulated neutrophils were evaluated by lucigenin-enhanced chemiluminescence (CL) and the activity of purified MPO was measured by SIEFED (Specific Immunological Extraction Followed by Enzymatic Detection), a technique for studying the direct interaction of a compound with the enzyme. The rind extracts of P. edulis possessed higher and dose-dependent inhibitory effects on CL response and on the peroxidase activity of MPO than total pulp extracts from both passion fruit species. The quantification of isoorientin in the extracts showed a correlation with their antioxidant activity, suggesting the potential of P. edulis rinds as functional food or as a possible source of natural flavonoids. (C) 2011 Elsevier Ltd. All rights reserved.

Flerskiktat papper : en sammanställning av historia, teknik och forskningsresultat

Until the beginning of the 1900:th century the paper making process was handicraft. The paper machines that have been developed since then are as impressing in size as fascinating when it comes to the technique. The process has always been improved to give a better paper for lower costs, with as short manufacture time as possible. Stratified forming has been a reality since 1830. From the beginning it was applied to board and paperboard. Now it is also the most common method for making tissue and one paper mill in Austria use it for fine paper. Stratified forming can be categorized as separate forming or simultaneous forming. Separate forming means using several headboxes and sometimes even several wires. Simultaneous forming means using only one stratified headbox. This method has many advantages over separate forming, inter alia improved economy, quality, wood exchange and higher runability of the paper machine. Several experiments have been done with simultaneous forming of different fibres by placing a fibre with high bulk in the middle layer and a smooth fibre on the surface layers. The results has shown that by using this method both the bending stiffness and surface properties are improved, or a lower grammage paper is obtained with maintaining quality. Simultaneous forming can also be used to stratify fillers in layers where they are most efficient. In that way both paper quality and economy is improved. Simultaneous forming is also used for fractionated pulp. Fractionation means separating springwood fibre from summerwood fibre, and placing them in separate layers. Research results of fractionated pulp show about the same result as simultaneous forming of different fibres.

The value of a saved tree : The lifecycle of CO2-emissions associated with the combination of printing paper and electricity production of wood in the U.S. and Sweden

The pulp- and paper production is a very energy intensive industry sector. Both Sweden and the U.S. are major pulpandpaper producers. This report examines the energy and the CO2-emission connected with the pulp- and paperindustry for the two countries from a lifecycle perspective.New technologies make it possible to increase the electricity production in the integrated pulp- andpaper mill through black liquor gasification and a combined cycle (BLGCC). That way, the mill canproduce excess electricity, which can be sold and replace electricity produced in power plants. In thisprocess the by-products that are formed at the pulp-making process is used as fuel to produce electricity.In pulp- and paper mills today the technology for generating energy from the by-product in aTomlinson boiler is not as efficient as it could be compared to the BLGCC technology. Scenarios havebeen designed to investigate the results from using the BLGCC technique using a life cycle analysis.Two scenarios are being represented by a 1994 mill in the U.S. and a 1994 mill in Sweden.The scenariosare based on the average energy intensity of pulp- and paper mills as operating in 1994 in the U.S.and Sweden respectively. The two other scenarios are constituted by a »reference mill« in the U.S. andSweden using state-of-the-art technology. We investigate the impact of varying recycling rates and totalenergy use and CO2-emissions from the production of printing and writing paper. To economize withthe wood and that way save trees, we can use the trees that are replaced by recycling in a biomassgasification combined cycle (BIGCC) to produce electricity in a power station. This produces extra electricitywith a lower CO2 intensity than electricity generated by, for example, coal-fired power plants.The lifecycle analysis in this thesis also includes the use of waste treatment in the paper lifecycle. Both Sweden and theU.S. are countries that recycle paper. Still there is a lot of paper waste, this paper is a part of the countries municipalsolid waste (MSW). A lot of the MSW is landfilled, but parts of it are incinerated to extract electricity. The thesis hasdesigned special scenarios for the use of MSW in the lifecycle analysis.This report is studying and comparing two different countries and two different efficiencies on theBLGCC in four different scenarios. This gives a wide survey and points to essential parameters to specificallyreflect on, when making assumptions in a lifecycle analysis. The report shows that there arethree key parameters that have to be carefully considered when making a lifecycle analysis of wood inan energy and CO2-emission perspective in the pulp- and paper mill in the U.S. and in Sweden. First,there is the energy efficiency in the pulp- and paper mill, then the efficiency of the BLGCC and last theCO2 intensity of the electricity displaced by BIGCC or BLGCC generatedelectricity. It also show that with the current technology that we havetoday, it is possible to produce CO2 free paper with a waste paper amountup to 30%. The thesis discusses the system boundaries and the assumptions.Further and more detailed research, including amongst others thesystem boundaries and forestry, is recommended for more specificanswers.

New activism and communication in Australian risk society : a case study of the Otway Ranges Environment Network

This paper overviews a case study of environmental grassroots activism in Victoria, Australia, between 1995 and 2003. The Otway Ranges Environment Network (OREN) is significant for its successful communication campaign to change forest practices and policy decision-making in the Otway Ranges, and for its intervention in a long-standing and exclusive relationship between government and the timber industry. This paper describes and analyses pivotal parts of the OREN campaign: firstly, the group's strategy to boycott paper and pulp manufacture Kimberly-Clark Australia; and secondly, its decision to participate in the West Victoria Regional Forest Agreement (RFA) process to negotiate the future of Otway forest. Informed by the empirical research and the works of social theorists Ulrich Beck and Jurgen Habermas, this paper outlines a strategic approach to communication that is effective, fair and sustainable, and that can be applied by other non-profits - especially those that operate in politically volatile environments with a grassroots agenda.

‘CHOU GAGS CRITICS IN BANDOENG or how the media framed Premier Zhou Enlai at the Bandung Conference, 1955

At the Asian-African Conference at Bandung, Indonesia, in April 1955, the world's press concentrated its gaze on Premier Zhou Enlai of the People's Republic of China. Premier Zhou's every gesture, interaction and statement was scrutinized for evidence that his motivations at Bandung were antagonistic to Western interests. This preoccupation with the motivations of the Chinese was, however, no new phenomenon. By 1955, literary tropes of the ‘Yellow Peril’ had been firmly established in the Western imagination and, after 1949, almost seamlessly made their transition into fears of infiltrating communist Chinese ‘Reds’.

The first half of this paper explores the historical roots of the West's perceptions of the Chinese, through the literary works of Daniel Defoe to the pulp fiction of Sax Rohmer's Dr Fu Manchu series, which ran from 1917 to 1959. It then examines how this negative template was mobilised by the print media at the height of the Cold War to characterize Premier Zhou Enlai, not only as untrustworthy, but also as antagonistically anti-Western. This reading of representations of Premier Zhou at Bandung, as well as the literary tropes propagated in support of eighteenth and nineteenth-century imperial expansion, exposes a history of Western (mis)interpretations of China, and sheds light upon the media network's role in constructing a Chinese enemy in the mid-1950s.

Preparation and characterization on cellulose nanofiber film

In this study, cellulose nanofibers were obtained from wood pulp using a chemo-mechanical method and thin films were made of these cellulose nanofibers. The morphology of the films was studied by scanning electron microscopy (SEM). SEM image analysis revealed that the films were composed of cellulose nanofibers with an average diameter of around 32 nm. Other properties were also characterized, including the degree of crystallinity by X-ray diffraction, chemical bonding by infrared attenuated total reflectance analysis, and thermal properties by differential scanning calorimetry. The foldable, strong, and optically translucent cellulose nanofiber films thus obtained have many potential applications as micro/nano electronic devices, biosensors and filtration media, etc.

By-product recovery in industrial wastewater pollution control

By-products from most industries become waste when they are not recovered. This article gives examples of by-product recovery from industries such as pulp and paper, dairy, pig farm and food processing.

Although the recovery of by-products will require new processes, the investments on those processes will be paid-back easily from the benefits brought by those by-products. Also, in order to have a sustainable development, by-product recover will play a significant role in all industries in the near future.

Fabrication of carbon nanofiber by pyrolysis of freeze-dried cellulose nanofiber

The possibility of fabricating carbon nanofibers from cellulose nanofibers was investigated. Cellulose nanofiber of ~50 nm in diameter was produced using ball milling in an eco-friendly manner. The effect of the drying techniques of cellulose nanofibers on the morphology of carbon residue was studied. After pyrolysis of freeze-dried cellulose nanofibers below 600 °C, amorphous carbon fibers of ~20 nm in diameter were obtained. The pyrolysis of oven-dried precursors resulted in the loss of original fibrous structures. The different results arising from the two drying techniques are attributed to the difference in the spatial distance between cellulose nanofiber precursors.

Novel polymer-ceramic composites for protection against ballistic fragments

For the first time, internally reinforced aggregate polymer ceramic composites were evaluated against fragment simulating projectiles (FSPs) of various calibers to investigate their ballistic impact response. Samples were prepared by mechanically mixing B4C and cBN over a range of ratios and combinations with either thermosetting phenolic or epoxy resin and aramid pulp. Dry mixtures were then molded in a closed die using a heated platen press. The resulting tiles were then mounted as ‘‘strike faces’’ to an aramid backing material using an epoxy resin. Backed targets were tested in a fully instrumented firing range against 5.56 mm FSPs to test ballistic limit. A further series of tests using 7.62, 12.5, and 20 mm FSPs was conducted to examine round deformation across a range of fragments calibers. Round deformations were measured after impact and plotted against shot velocity. It was found that the polymer ceramic composite materials were effective round deformers and, like sintered ceramic strike faces, demonstrated improved ballistic performance at an equivalent areal density and impressive multihit capability.