Arabinosylated phenolics obtained from SO2‐steam‐pretreated sugarcane bagasse

A pentose‐rich hydrolysate fraction obtained by extraction of steam‐pretreated sugarcane bagasse was analysed with regard to dissolved phenolics. The liquid obtained after steam pretreatment (2% SO₂ (w/w) at 190 °C for 5 min) was divided into two parts: one containing dissolved compounds originating from hemicellulose (with xylose as the dominating compound), and the other containing predominantly dissolved compounds originating from lignin. Using nuclear magnetic resonance, the main dissolved compounds originating from lignin were identified as the glycosylated aromatics, 5‐O‐(trans‐feruloyl)‐L‐Arabinofuranose and 5‐O‐(trans‐coumaroyl)‐L‐Arabinofuranose, together with p‐coumaric acid and small amounts of more common free phenolics such as p‐hydroxybenzaldehyde, p‐hydroxybenzoic acid and vanillin. The phenolic compounds were analysed and quantified using reversed‐phase high‐performance liquid chromatography. The findings show that SO₂ steam explosion opened up new degradation pathways during lignin degradation. Copyright © 2012 Society of Chemical Industry     

Chemical images

Chemical sensors can be used to generate a vast amount of information about the emissions from bio- and chemical processes, from food and bacteria and from a number of products. These emissions are either wanted or should be avoided. Wolfgang Göpel was one of those who recognized early the large potential of chemical sensor arrays and different modes of operation of a given sensor. We describe how large area field effect devices, with catalytic metal gates, can be used for the construction of a response image of a gaseous emission. More specifically, we discuss the new possibilities obtained through the use of catalytic metals with a gradient in thickness. Some basic features of such sensing surfaces are demonstrated and, finally, time-dependent response images from aging meat are used to demonstrate the potential of the method used. It is based on a scanning light pulse technique (SLPT) which measures local polarization or work function changes in two dimensions and, e.g. a sensing surface consisting of bands of different catalytic metals with a gradient in thickness.     

Separate versus Simultaneous Saccharification and Fermentation of Two‐Step Steam Pretreated Softwood for Ethanol Production

Abstract

In two previous studies, optimal conditions were identified for two‐step steam pretreatment of SO₂‐ and H₂SO₄‐impregnated softwood. In the present study the yield of sugar and ethanol was determined in a process development unit where pretreatment was performed in a 10‐L reactor and simultaneous saccharification and fermentation (SSF) or enzymatic hydrolysis (EH) were performed in 30‐L reactors. The study showed that a steam pretreatment reactor should be larger than 2 L to yield acceptable results. Two pretreatment combinations were studied. In the H₂SO₄ case, the first pretreatment step was at 180°C for 10 min with 0.5% H₂SO₄ and the second step at 210°C for 2 min with 1% H₂SO₄. In the SO₂ case, first step was at 190°C for 2 min followed by a second step at 210°C for 5 min. The concentration of SO₂ was 3% in both steps. EH and SSF were performed on the whole slurry after the second pretreatment step to determine the yield of sugars and ethanol. The liquid after the first pretreatment step was also analyzed and fermented. When SSF and EH were performed at the same dry matter content and enzymatic activity, the ethanol yield in SSF exceeded the yield obtained with EH in both pretreatment cases, even when 100% yield in the fermentation step was assumed. Thus SSF is a better process if yield is the main priority. Comparison of the yields with the two acid catalysts showed higher yields with SO₂ in both SSF and EH. The overall ethanol yield following SSF of SO₂‐impregnated and pretreated wood reached 81% of the theoretical, that is, 357 liters per metric ton of dry raw material.     

On the physics of power,energy and economics of renewable electric energy sources - Part II

Renewable Energy Technologies (RETs) are often recognized as less competitive than traditional electric energy conversion systems. Obstacles with renewable electric energy conversion systems are often referred to the intermittency of the energy sources [1] and the relatively high maintenance cost. However, due to an intensified discourse on climate change and its effects, it has from a societal point of view, become more desirable to adopt and install CO₂ neutral power plants. Even if this has increased the competitiveness of RETs in a political sense, the new goals for RET installations must also be met with economical viability. We propose that the direction of technical development, as well as the chosen technology in new installations, should not primarily be determined by policies, but by the basic physical properties of the energy source and the associated potential for inexpensive energy production. This potential is the basic entity that drives the payback of the investment of a specific RET power plant. With regard to this, we argue that the total electric energy conversion system must be considered if effective power production is to be achieved, with focus on the possible number of full loading hours and the Degree of Utilization [2]. This will increase the cost efficiency and economical competitiveness of RET investments, and could enhance faster diffusion of new innovations and installations without over-optimistic subsidies. This paper elaborates on the overall problem of the economy of renewable electric energy conversion systems by studying the interface between physics, engineering and economy reported for RET power plants in different scientific publications. The core objective is to show the practical use of the Degree of Utilization and how the concept is crucial for the design and economical optimization disregarding subsidies. The results clearly indicate that the future political regulative frameworks should consider the choice of renewable energy source since this strongly affects the economical output from the RET power plants.     

Options for the Swedish steel industry - Energy efficiency measures and fuel conversion

The processes of iron and steel making are energy intensive and consume large quantities of electricity and fossil fuels. In order to meet future climate targets and energy prices, the iron and steel industry has to improve its energy and resource efficiency. For the iron and steel industry to utilize its energy resources more efficiently and at the same time reduce its CO₂ emissions a number of options are available. In this paper, opportunities for both integrated and scrap-based steel plants are presented and some of the options are electricity production, fuel conversion, methane reforming of coke oven gas and partnership in industrial symbiosis. The options are evaluated from a system perspective and more specific measures are reported for two Swedish case companies: SSAB Strip Products and Sandvik AB. The survey shows that both case companies have great potentials to reduce their CO₂ emissions.     

Upper Cretaceous–Cenozoic clay minerals of the Baikal region (eastern Siberia)

The Baikal region is located in a single climate zone and includes the Baikal foredeep on the eastern margin of the Siberian craton and the Baikal rift evolving at the western boundary of the Baikal orogenic area. Late Cretaceous–Cenozoic deposition in the two dissimilar tectonic units occurred in different environments, which is recorded in the architecture of sedimentary sequences and in the stratigraphic distribution of clay mineralogy.Clay minerals are mostly derived from weathered rocks of different ages. The geological ages of the source weathering mantles and their regular changes in different tectonic and climatic conditions can be inferred from the stratigraphic position in the Upper Cretaceous–Cenozoic sedimentary sequences that fill the Baikal foredeep. These inferences agree with data on fossil soils, flora, and fauna. Clay minerals show genetic relationships with stages of postdepositional alteration and processes of soil formation and hydrothermalism.In general, the Cenozoic history of erosion, deposition, and postdepositional changes of rocks in the Baikal region has been controlled by the interplay of climate and tectonic factors.