Search results for "engineering.material"
showing 10 items of 2352 documents
NOx selective catalytic reduction at high temperatures with mixed oxides derived from layered double hydroxides
2012
[EN] Mixed oxides derived from layered double hydroxides (LDHs) have been investigated as potential catalysts for the NOx removal at high temperatures. The best results were obtained with Co–Al mixed oxides derived from LDHs that are active at 750 ◦C in the presence of oxygen and water. These catalysts could reduce or/and decompose the NOx formed in the dense phase of the FCC regenerator, being deactivated at oxygen concentrations higher than 1.5%. Nevertheless this deactivation is not permanent and they would be regenerated after reduction with hydrogen at 530 ◦C. The influence of the layered double hydroxides (LDHs) preparation method on the catalyst activity was studied, observing that t…
Molybdenum blue: Binding to collagen fibres and microcrystal formation
2005
Collagen fibres have been shown by transmission electron microscopy to progressively bind the polyoxomolybdate ring-complex, termed molybdenum blue. Nucleation of cuboidal molybdenum blue microcrystals occurs on the surface of the collagen fibres, leading eventually to extensive coating of the fibres with microcrystals.
Hydrodesulfurization cobalt-based catalysts modified by gold
2007
Cobalt catalysts supported on amorphous SiO2 and ordered mesoporous silica (MCM-41) were prepared by incipient wetness impregnation. Gold was added by consecutive impregnation or by co-impregnation. The materials were characterised by XPS, XRD and TPR techniques and evaluated in the hydrodesulfurization (HDS) of thiophene in order to investigate the effect of the noble metal on the structure and on the catalytic behaviour of the supported cobalt. Co/MCM-41 exhibited higher HDS activity and higher stability than the Co/SiO2. Moreover, in contrast to silica case, the gold impregnated MCM-41, produced an enhancement of the cobalt catalytic activity, and this is likely to be related to an incre…
Production of Phosphorescent Coatings on 6082 Aluminum Using Sr0.95Eu0.02Dy0.03Al2O4-δ Powder and Plasma Electrolytic Oxidation
2019
In this study, a new approach for producing phosphorescent aluminum coatings was studied. Using the plasma electrolytic oxidation (PEO) process, a porous oxide coating was produced on the Al6082 aluminum alloy substrate. Afterwards, activated strontium aluminate (SrAl2O4: Eu2+, Dy3+) powder was filled into the cavities and pores of the PEO coating, which resulted in a surface that exhibits long-lasting luminescence. The structural and optical properties were studied using XRD, SEM, and photoluminescence measurements. It was found that the treatment time affects the morphology of the coating, which influences the amount of strontium aluminate powder that can be incorporated into the coating …
Covalently modified nanoclays: synthesis, properties and applications
2020
Abstract Clay minerals are phyllosilicates of nanoscale dimensions. According to their ability to entrap and release organic moieties, they have found applications in several fields, such as drug carrier and delivery, support for catalyst, environmental remediation and filler for polymeric matrices. The possibility to modify, by covalent linkage, their surfaces gives the possibility to form new nanomaterials with improved properties respect to the pristine clay minerals. In this chapter, the modifications of the siloxane surfaces of the most representative clay minerals, namely montmorillonite, sepiolites, laponite and halloysite were reviewed and discussed.
Barrier properties of chitosan coated polyethylene
2012
The transfer properties of chitosan coated polyethylene (PE) films were studied. The barrier properties of non coated PE were not affected by relative humidity changes. The presence of the hydrophilic chitosan layer acted as a water reservoir on the polyethylene film surface which significantly promoted its sensitivity to the water vapour. The water vapour permeability increased 1.85 times at a higher RH. Coated PE films showed more than two-order decrease in the oxygen permeability (PO2) and three-order-decrease in the carbon dioxide permeability (PCO2). When the chitosan coated PE surface was exposed to the water vapour, the PO2 and the PCO2 were significantly increased. However, the perm…
Halloysite Nanotubes Coated by Chitosan for the Controlled Release of Khellin
2020
In this work, we have developed a novel strategy to prepare hybrid nanostructures with controlled release properties towards khellin by exploiting the electrostatic interactions between chitosan and halloysite nanotubes (HNT). Firstly, khellin was loaded into the HNT lumen by the vacuum-assisted procedure. The drug confinement within the halloysite cavity has been proved by water contact angle experiments on the HNT/khellin tablets. Therefore, the loaded nanotubes were coated with chitosan as a consequence of the attractions between the cationic biopolymer and the halloysite outer surface, which is negatively charged in a wide pH range. The effect of the ionic strength of the aqueous medium…
Creating Global Markets : Seaborne Trade in Pulp and Paper Products Over the Last 400 Years
2018
The declining cost of sea transport has been a necessary condition for the growth of the global pulp and paper industry, especially in regions remote from economic centres. Thus, pulp and paper industries and international shipping have coevolved, especially since the 1960s, enabling producers to tap global markets and develop global production chains. The paper products trade flows, however, have changed a number of times over the last 400 years. This chapter describes and explains these developments and shows how the technological solutions in global shipping and strategic choices among the pulp and paper companies have been interdependent, especially since the 1960s. peerReviewed
Layered Double Hydroxides: A Toolbox for Chemistry and Biology
2019
Layered double hydroxides (LDHs) are an emergent class of biocompatible inorganic lamellar nanomaterials that have attracted significant research interest owing to their high surface-to-volume ratio, the capability to accumulate specific molecules, and the timely release to targets. Their unique properties have been employed for applications in organic catalysis, photocatalysis, sensors, drug delivery, and cell biology. Given the widespread contemporary interest in these topics, time-to-time it urges to review the recent progresses. This review aims to summarize the most recent cutting-edge reports appearing in the last years. It firstly focuses on the application of LDHs as catalysts in re…
Assessment of Effectiveness of Organo-Mineral Fertilizer Made of Coffee Spent Grounds and Biomass Ash
2019
Optimization of the biodegradable wastes management is one of the main goals of the activities taken up in the European Union. The aim of the present paper is to define the possibilities of supporting the process of golden rod yield (Solidago canadensis L.) by using different mineral-organic fertilizers, in a form of granulated substances, produced from extracted coffee wastes (CSG) as well as from ash which is the result of woody biomass combustion. Golden rod, as a potential energetic plant, is very easy to grow because it covers the grounds which are not utilized agriculturally or the ones localised in the close neighbourhood of industrial areas. For certain experimental purposes, a fiel…