Environmentally friendly flameretardants for cellulose-basedmaterials

Flame retardants are commonly used as a way to reduce the risk of fire. However, many of the currently used flame retardants are toxic and hazardous to the environment. Therefore, there are incentives to find safer alternatives. In nature, there are many substances that can function as non-toxic and environmentally friendly flame retardants. Phytic acid is the main storage form of phosphorus in plants and can be found in e.g. nuts and cereals. Amino acids are the building blocks of enzymes and proteins. Many common metal ions are important nutrients.Reference groupAnders Lundberg, Swedish Civil Contingencies Agency (MSB)Leif Andersson, ProtegaMattias Delin, BrandforskRobert McNamee, RISEThomas Gell, GellCon</p

Environmentally friendly flameretardants for cellulose-basedmaterials

Flame retardants are commonly used as a way to reduce the risk of fire. However, many of the currently used flame retardants are toxic and hazardous to the environment. Therefore, there are incentives to find safer alternatives. In nature, there are many substances that can function as non-toxic and environmentally friendly flame retardants. Phytic acid is the main storage form of phosphorus in plants and can be found in e.g. nuts and cereals. Amino acids are the building blocks of enzymes and proteins. Many common metal ions are important nutrients.Reference groupAnders Lundberg, Swedish Civil Contingencies Agency (MSB)Leif Andersson, ProtegaMattias Delin, BrandforskRobert McNamee, RISEThomas Gell, GellCon</p

Studies on environmentally friendly flame retardants for cellulose-based materials

Phosphorus based flame retardants are considered to be the best for cellulose-based materials such as cotton and wood. A non-toxic naturally occurring substance with high phosphorus content is phytic acid, which is used by plants as the main storage of phosphorus. It is prevalent in grains and seeds, so we eat it every day. Phytic acid and phytate complexes with various common and non-toxic metal ions or ammonia have been studied on cotton and wood in orderto systematically assess their performance as flame retardants and elucidate their mechanismsof action. Simple combustion tests have been used to gain a first overview of the relative performance of the flame retardants depending on which ion is combined with the phytic acid, and in which proportions. Analytical methods such as TGA and calorimetry have been used to investigate the thermal properties and thermal degradation of the samples. Spectroscopic techniques suchas MAS NMR have been used to explain the chemistry behind the thermal degradation mechanisms in molecular detail. The main focus has been on cotton samples, but an efficient methodology to control the humidity of wood samples in lab scale has been developed for future investigations on wood. Phytic acid and its complexes have a flame retarding effect on both cotton and wood. The thermal process is similar on both materials. The mechanism is low-temperature charring giving less combustible degradation products, followed by cooling polymerization of the phosphate groups in the phytic acid, and formation of a second barrier to prevent the mixture of combustible volatiles and oxygen. It is important to have ionizable protons available in the flame retardant to induce the main mechanism of charring. Cone calorimeter tests on cotton samples show that the samples self-extinguish. Sodium phytates have a better performance than calcium phytates, as shown from combustion tests and FIGRA index on cotton samples. Possibly the superior flame retarding effect of sodium compared to the other ions is because ofthe radical quenching ability of alkali metals, but further investigations are needed into thisissue. Some of the results are also available in Bachelor and Master theses, and in a recently accepted paper in Green Materials Special Issue on Sustainable Flame Retardants. The results may be of interest to the scientific community as well as for companies and organizations that work for a fire-safe and sustainable living environment

Photosensitized dimerization in pyrimidine-based thin solid films

Thin solid films of thymine and uracil derivatives, incorporating a photosensitizer in the film, were prepared on quartz surfaces using a dip-coating technique. Photosensitized dimerization in these thin solid films was investigated in this study and compared with the conventional, non-photosensitized reaction. Both carbonyl and p-aminobenzoic compounds were selected as photosensitizers. It was found that only p-aminobenzoic compounds such as p-aminobenzoic acid and N-dodecyl p-aminobenzoic acid were effective in causing the photosensitized dimerization of thymine, upon exposure to light of wavelength 313 nm. Uracil surfaces, however, do not photodimerize under these conditions. The concentration of photosensitizer and the solvent selected in the dip-coating process strongly influenced the dimerization process. The reaction rate of sensitized dimerization follows a pseudo-first order reaction.

Solid state characterization of sodium eritadenate

Knowledge of the solid state is of great importance in the development of a new active pharmaceutical ingredient, since the solid form often dictates the properties and performance of the drug. In the present study, solid state characteristics of the sodium salt of the candidate cholesterol reducing compound eritadenine, 2(R), 3(R))-dihydroxy-4-(9-adenyl)-butanoic acid, were investigated. The compound was crystallized by slow cooling from water and various aqueous ethanol solutions, at different temperatures. Further, the compound solution was subjected to lyophilization and to high vacuum drying. The resulting solids were screened for polymorphism by micro Raman spectroscopy (λex = 830 nm) and the crystallinity was investigated by X-ray powder diffraction. Further, thermal analysis was applied to study possible occurrence of solvates or hydrates. Solids obtained from slow cooling showed crystallinity, whereas rapid cooling gave rise to more amorphous solids. Analysis of difference spectra of the Raman data for solids obtained from slow cooling of solution revealed subtle differences in the structures between crystals derived from pure water and crystals derived from aqueous ethanol solutions. Finally, from the thermal analysis it was deduced that crystals obtained from pure water were stoichiometrically dihydrates whereas crystals obtained from aqueous ethanol solutions were 2.5 hydrates; this formation of different hydrates were supported by the Raman difference analysis.Validerad; 2011; 20110831 (joen

A study to examine the ageing behaviour of cold plasma-treated agricultural seeds

Abstract Cold plasma (low pressure) technology has been effectively used to boost the germination and growth of various crops in recent decades. The durability of these plasma-treated seeds is essential because of the need to store and distribute the seeds at different locations. However, these ageing effects are often not ascertained and reported because germination and related tests are carried out within a short time after the plasma-treatment. This research aims to fill that knowledge gap by subjecting three different types of seeds (and precursors): Bambara groundnuts (water), chilli (oxygen), and papaya (oxygen) to cold plasma-treatment. Common mechanisms found for these diverse seed types and treatment conditions were the physical and chemical changes induced by the physical etching and the cold plasma on the seeds and subsequent oxidation, which promoted germination and growth. The high glass transition temperature of the lignin-cellulose prevented any physical restructuring of the surfaces while maintaining the chemical changes to continue to promote the seeds germination and growth. These changes were monitored over 60 days of ageing using water contact angle (WCA), water uptake, electrical conductivity, field emission scanning electron microscopy (FE-SEM) and X-ray photoelectron spectroscopy (XPS). The vacuum effect was also investigated to separate its effect from cold plasma (low pressure). This finding offers a framework for determining how long agricultural seeds that have received plasma treatment can be used. Additionally, there is a need to transfer this research from the lab to the field. Once the impact of plasma treatment on seeds has been estimated, it will be simple to do so

Flotation selectivity of novel alkyl dicarboxylate reagents for calcite-fluorite separation

A series of amino acid-based surfactants with a fixed alkyl chain length and with two carboxyl groups separated by a spacer of one, two or three carbon atoms have been synthesized and evaluated as potential collectors for flotation of calcite and fluorite. A monocarboxylate amino acid-based surfactant having the same length of the hydrocarbon tail was also included for comparison in the study. Experiments using a Hallimond flotation tube showed that although the flotation reagents solely differ in terms of spacer, their efficacy in terms of flotation recovery varied very much. Whereas on calcite at pH 10.5 only the monocarboxylate collector gave a high yield, on fluorite at the same pH both the monocarboxylate and the dicarboxylate collectors with one carbon between the carboxyl groups gave good results. On calcite at the natural pH the monocarboxylate collector was most efficient but the dicarboxylate collectors with a two and a three-carbon spacer also gave a reasonable recovery. On fluorite at the natural pH the dicarboxylate collectors with a two- and a three-carbon spacer were most efficient. The zeta-potential and the flotation recovery of the mineral particles as a function of added collector were assessed and the adsorption was also monitored by diffuse reflectance infra-red spectroscopy. Taken together, the results showed that small changes in the head group region of the collector can radically affect flotation recovery. This type of knowledge is important to understand flotation selectivity in a mixture of similar minerals

Revisiting sulphide mineral (bio) processing : a few priorities and directions

Large efforts are being made to streamline the conventional (chemical and physical) technological schemes of ore processing, remediation and environmental protection towards reducing overall costs, limiting the use of dangerous substances, decreasing waste streams and improving waste disposal and recycling practice. Hitherto, search for such innovations has been performed mainly empirically and there is an urgent need to shift these technologies to be more innovative and effective. Alternative biotechnological solutions and solutions mimicking natural processes are also being proposed. However, except for bioleaching, practical exploitation of the biotechnological potential in extractive industries and accompanying environmental protection measures remains far from feasibility.Understanding of the fundamental concepts of aquatic chemistry of minerals–selective adsorption and selective redox reactions at mineral–bacteria–solution interfaces, impact innovating conventional and bio-flotation, as well as (bio)remediation/detoxification of mineral and chemical wastes. Molecular-level knowledge and coherent understanding of minerals contacted with aqueous solutions is required that underlie great opportunities in controlling abiotic and biotic mineral–solution interfaces towards the grand challenge of tomorrow’s science and mineral processing technology.Godkänd; 2013; 20130412 (alijav

Selective flotation of calcium minerals using double-headed collectors

A study was performed involving a series of double-headed carboxylate collectors with varying distance between the head groups (one, two or three carbon atoms). A collector with the same alkyl chain length but with only one carboxylate group was also included. All these were amino-acid based amphiphiles and the polar head group was connected to the hydrophobic tail via an amide linkage. Selective flotation recovery of different calcium minerals using these collectors was investigated. The double-headed collector with one carbon atom between the carboxylate groups was an apatite and fluorite specific reagent while the monocarboxylate surfactant showed high specificity for calcite. The flotation behavior of a simple conventional collector of the same alkyl chain length, a fatty acid salt, was also determined under identical flotation conditions in order to understand the effect of the amide group. Complementary experiments (ζ potential measurements, adsorption isotherm determinations) were also performed for these reagents. In order to shed light on the selectivity obtained with the dicarboxylate surfactants, the distances between the head groups were calculated and compared with the distances between neighboring calcium atoms on the surface of the minerals. It was found that the high degree of selectivity could be rationalized by perfect matching of these distances. To the best of our knowledge this is the first study where flotation selectivity in complex calcium mineral systems has been explained in terms of molecular recognition governing the interaction between the collector and the mineral surface.Validerad;2019;Nivå 2;2019-07-08 (johcin)</p