Development and experimental validation of an overlay mortar with biocide activity

Biodeterioration of concrete by microorganism colonisation may be a problem in several structures, especially in irrigation and hydroelectric canals. The main problem in such structures is the proliferation of algae and cyanobacteria that affect the performance of the structure, increase the maintenance costs and affects its durability. A research was conducted to develop a novel cement-based material with biocide activity that can be used as an overlay mortar in existing structures, such as canals and pipes. With this aim, ten commercial biocides were evaluated in a laboratory campaign to assess the effectiveness of the compounds against the microbial colonisation of concrete. Both mono- and multicomponent formulations were designed from the commercial products, to increase their antimicrobial effect obtaining a set of biocide formulations. The formulations were submitted to a flowchart process to determine their influence on the physical properties of the concrete, evaluate the release of the actives, and their antimicrobial efficiency both before and after accelerated aging processes. During the campaign, some formulations were observed to diminish the strength of the concrete. Such behaviour was normally due to the interaction of the active with the cement hydration process. Other formulations showed a high release of active from the concrete in water, compromising the durability of the treatment. In general, monocomponent formulations did not succeed to fulfill all the requirements, thus multicomponent formulations were analysed. One studied multicomponent formulation presented particularly good results in all properties analysed. This product did not significantly change the properties of concrete and the release of active in water from the concrete was low, while the antimicrobial effects were long lasting.Peer ReviewedPostprint (author's final draft

Efficient uses of some types of surfactant products

The present work is part of a more complex study referring to chemical substances known under the name of „surfactants” or „tensioactive agents” which can alter the conductivity of fibers, textile materials, etc. in order to diminish some negative physiological effects on the human body. The use of raw materials, indigenous or imported, refers to the strategy adopted by each firm, concerning their own technology, which should include both organization and management of production processes, and ways of introducing the technical progress with economic efficiency.surfactant, textile industry, latex, deformer, isoelectric point, technical progress

Epoxy resins produce improved plastic scintillators

Plastic scintillator produced by the substitution of epoxy resins for the commonly used polystyrene is easy to cast, stable at room temperature, and has the desirable properties of a thermoset or cross-linked system. Such scintillators can be immersed directly in strong solvents, an advantage in many chemical and biological experiments

Scalable Freeze-Tape-Casting Fabrication and Pore Structure Analysis of 3D LLZO Solid-State Electrolytes.

Nonflammable solid-state electrolytes can potentially address the reliability and energy density limitations of lithium-ion batteries. Garnet-structured oxides such as Li7La3Zr2O12 (LLZO) are some of the most promising candidates for solid-state devices. Here, three-dimensional (3D) solid-state LLZO frameworks with low tortuosity pore channels are proposed as scaffolds, into which active materials and other components can be infiltrated to make composite electrodes for solid-state batteries. To make the scaffolds, we employed aqueous freeze tape casting (FTC), a scalable and environmentally friendly method to produce porous LLZO structures. Using synchrotron radiation hard X-ray microcomputed tomography, we confirmed that LLZO films with porosities of up to 75% were successfully fabricated from slurries with a relatively wide concentration range. The acicular pore size and shape at different depths of scaffolds were quantified by fitting the pore shapes with ellipses, determining the long and short axes and their ratios, and investigating the equivalent diameter distribution. The results show that relatively homogeneous pore sizes and shapes were sustained over a long range along the thickness of the scaffold. Additionally, these pores had low tortuosity and the wall thickness distributions were found to be highly homogeneous. These are desirable characteristics for 3D solid electrolytes for composite electrodes, in terms of both the ease of active material infiltration and also minimization of Li diffusion distances in electrodes. The advantages of the FTC scaffolds are demonstrated by the improved conductivity of LLZO scaffolds infiltrated with poly(ethylene oxide)/lithium bis(trifluoromethanesulfonyl)imide (PEO/LITFSI) compared to those of PEO/LiTFSI films alone or composites containing LLZO particles

Wave propagation through alumina-porous alumina laminates

A Brazilian disk geometry of an alumina layered composite with alternating dense and porous layers was dynamically loaded using a Split-Hopkinson Pressure Bar (SHPB)apparatus under compression. High-speed imaging and transmitted force measurements were used to gain an insight into stress wave propagation and mitigation through such a layered system. Uniformly distributed porosities of 20 and 50 vol % were introduced into the interlayers by the addition of fine graphite particles which volatilized during heat treatment. Brazilian disk samples were cut from the cylinders which were drilled out of the sintered laminated sample. The disks were subjected to dynamic impact loading in perpendicular and parallel orientations to the layers in order to investigate the influence of the direction of impact. The dynamic failure process of the layered ceramic consisted of the initiation and propagation of the cracks mainly along the interphases of the layers. Upon impact, the impact energy was dissipated through fracture in parallel orientation (0 deg) but transmitted in perpendicular (90 deg) orientations. The high degree of correlation between the transmitted force, microstructure and orientation in which the layered systems were impacted is discussed.Comment: 39 pages, 14 figures, 2 tables. Accepted for publication in the Journal of the European Ceramic Societ

Development of defoamer system for plastic painting water-dispersing paint

The basic types of defoamers and their applicability in different systems. Determination evaluation criteria steps defoamers. The regularities of the actions of defoamers of different chemical nature, and their mixtures in water-dispersion paint for painting of plastic. Obtained data set for defoaming action of additives of different chemical nature. The dependence of the speed of defoaming from chemical nature of defoamers and their number is studied. Found optimal concentration of defoamers and their mixtures in water dispersion system for painting of plastic products showed the presence of a synergistic effect when using a mixture of defoamers in the present systems. The mechanism of their defoaming actions was suggest

Tannin-boron wood preservatives

Tannin-boron wood preservatives are alternative products to replace water-borne formulations based on copper. Interesting results in protection against fungus (pycnoporus sanguineus) were achieved with formulations based of 20% tannin solutions containing boric acid (Thevenon et al. 2009). In this paper two upgrades are introduced: extension of preservation properties to softwood species (scots pine) and analysis of the side-properties achieved after treatment. A detailed study on tannin penetration in beech and scots pine is presented. Microscope analysis demonstrates that impregnation in scots pine have two preferential directions: Longitudinal through tracheids and radial through parenchyma rays, while in beech the liquid penetrates the wood cell mainly longitudinally through large and easy accessible vessels. Commercialization of exterior-door wood preservative will be also dependent on the side-properties derived from the treatment. For this reason, properties such as mechanical resistance and behavior against fire have been investigated. The mechanical tests have shown a strong increasing of compression resistance and surface hardness for beech and scots pine samples. The tests against fire have been monitored considering ignition, flame and ember time. A broad positive effect on fire-repellence is shown when wood is treated with tannin-boron formulations. (Résumé d'auteur

Dispersants and Seafood Safety Assessment of the potential impact of Corexit® oil dispersants on seafood safety

The April 20, 2010 explosion and subsequent sinking of the Deepwater Horizon oil production platform (DWH) resulted in the largest oil spill in U.S. history. On April 29th, a Spill of National Significance was declared as roughly 53 thousand barrels of oil per day flowed into the Gulf of Mexico (GOM). The U.S. Coast Guard estimated 4.9 million barrels of crude oil escaped before the damaged DWH wellhead was sealed on July 15, 2010 (National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling 2010). Oil spill clean-up methods included skimming operations, burning of surface oil, siphoning oil into tankers directly from the wellhead, and the application of chemical dispersants. The first 3 methods mentioned above physically removed spilled oil from GOM waters. The last method, chemical dispersion, distributed insoluble fractions of the oil into the water-column. This was done for 3 reasons: 1) to reduce the exposure of response personnel at-sea to volatile organic compounds emanating from the surface slick; 2) to prevent concentrated surface oil from reaching, and damaging, fragile coastal wetlands, beaches and shoreline communities; and 3) to accelerate the break-down of spilled oil by natural microorganisms in the environment. The oil spill response contingency plan (RCP) applicable to the GOM (EPA Regions 4 and 6 within the National Response Plan framework) pre-authorized the use of Nalco Co. (Naperville, IL) oil dispersants Corexit® 9527 and Corexit® 9500 among other pre-approved product formulations. From April 22 to July 19, 2010 an estimated 1.1 million gallons of Corexit® dispersant were applied over approximately 300 square miles of oiled surface waters in the GOM and 771,000 gallons were injected directly into the oil free-flowing from the wellhead 5,100 feet beneath the surface (National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling 2010). Corexit® 9527 comprised approximately 215,000 gallons (~11%) of the total dispersant volume applied to the surface oil slick and was discontinued on May 22. The unprecedented volume of chemical dispersants used to combat the DWH oil spill elicited public concerns for the health of responders, coastal communities, marine life, and the safety of seafood from impacted areas of the GOM. This document will address the latter of these concerns

Chemical characterization of pitch deposits produced in the manufacturing of high-quality paper pulps from hemp fibers

Instituto de Recursos Naturales y Agrobiología, CSIC, P.O. Box 1052, E-41080, Seville, Spain E-mail address: [email protected] composition of pitch deposits occurring in pulp sheets and mill circuits during soda/anthraquinone pulping and elemental chlorine-free pulp bleaching of bast fibers of industrial hemp (Cannabis sativa) has been studied. Pitch deposits were extracted with acetone, and the extracts analyzed by gas chromatography (GC) and gas chromatography/mass spectrometry (GC/MS). Acetone extracts (15-25% of pitch deposits) were constituted by the defoamers used at the mill and by lipophilic extractives from hemp fibers. Acetone-insoluble residues (75-85% of pitch deposits) were analyzed by pyrolysis-GC/MS in the presence and absence of tetramethylammonium hydroxide. These residues were constituted by salts of fatty acids (arising from hemp fibers) with calcium, magnesium, aluminum and other cations that were identified in the deposits. It was concluded that inappropriate use of defoamer together with the presence of multivalent ions seemed to be among the causes of hemp extractives deposition in the pitch problems reported here.This study has been supported by the Spanish Ministerio de Ciencia y Tecnología (MCYT) and FEDER funds (projects 2FD97-0896-C02-02 and AGL2002-00393). A.G. acknowledges a "Ramón y Cajal" contract of the Spanish MCYT. We also thank CELESA (Tortosa, Spain) for providing the samples.Peer reviewe

Stabilizing biopolymers in water-based drilling fluids at high temperature using antioxidants, a formate salt, and polyglycol

Biopolymers degrade in water-based drilling fluids when exposed to high temperatures for some time, thus leading to hole-cleaning problems such as stuck pipe. To stabilise biopolymers in drilling fluids, the mechanisms by which they degrade at elevated temperatures must be understood. The degradation mechanisms of thermally labile biopolymers, therefore, include acid-catalysed hydrolysis and oxidation-reduction (redox) reactions. In this paper, an attempt is, therefore, made to investigate whether the combination of anti-oxidants, formate salt, and polyglycol could stabilise biopolymers in water-based drilling fluids with pH 8 to 10 above 200°C. Novel clay-based drilling fluids were formulated with sodium carbonate, sodium bicarbonate, biopolymers, antioxidants, a formate salt, a defoamer and polyglycol. The rheological properties of the drilling fluid formulations were measured using Model 800 and Model 1100 viscometers before and after hot-rolling dynamically in a roller oven for sixteen hours to condition the fluids. Presented results showed that xanthan gum in bentonite-water suspension remained stable up to 1000°C, and konjac gum in bentonite-water suspension remained stable up to 65°C. Experimental data also indicated that after dynamic aging for 16 hours, the antioxidant, formate salt and polyglycol increased the stability temperatures of the biopolymers - konjac gum and xanthan gum – in water-based drilling fluid formulations above 200°C. The best additives package that increased the stability temperatures of the biopolymers was potassium formate, sodium erythorbate, and 0.7% polyethene glycol. This additive package also maintained the suspension capability of the drilling fluid formulations. These additives can, therefore, be used to stabilise water-based drilling fluids containing biopolymers in the 150-232°C temperature range without using expensive and formation damaging synthetic polymers