The determination of inorganic phosphorus compounds by using molecular emission cavity analysis

The chemical and spectral interferences on the HPO emission within the cavity are investigated. Alkali metals, copper, manganese, iron and sulphate all interfere spectrally, and the alkali metals also suppress the HPO emission. A standard addition method after a batch ion-exchange resin treatment of the sample solution is proposed for the determination of phosphorus (1–1000 mg l^?1 P) in solutions of inorganic samples (e.g., rocks).     

Investigations on the flame-retardation of cellulosic fibrous materials

The thermal behaviours of untreated cellulose (cotton) and samples treated with phosphorus and nitrogen-containing flame-retardants have been studied by means of the derivatograph and quantitative DTA, with the aim of revealing the advantageous features of thermal analysis in the investigation of the flame-retardation of cellulose substrates. The complex thermoanalytical method applied proved to be suitable for the investigation of the efficiency of flame-retardation in parallel with the oxygen index method and the determination of the phosphorus content of the sample. The efficiencies obtained with different methods are in correlation.

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Zusammenfassung Das thermische Verhalten unbehandelter Zellulose (Baumwolle) und mit phosphor- und stickstoffhaltigen Imprägniermitteln behandelter Proben wurde mit Hilfe des Derivatographen und der quantitativen DTA untersucht, um die vorteilhaften Eigenschaften der Thermoanalyse bei der Untersuchung der flammensicheren Imprägnierung von Zellulosesubstraten zu zeigen. Die angewandte komplexe thermoanalytische Methode erwies sich zur Untersuchung der Wirksamkeit der Imprägnierung im Paralleleinsatz mit der Sauerstoffindex-Methode und der Bestimmung des Phosphorgehalts der Probe als geeignet. Die mit den verschiedenen Methoden erhaltenen Wirksamkeitswerte stimmten gut überein.

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Résumé Dans le but de montrer les avantages que présente l'analyse thermique pour l'étude de l'effet des ignifuges sur les substrats cellulosiques, le comportement thermique de la cellulose non traitée (coton) et d'échantillons traités par des ignifuges contenant du phosphore ou de l'azote a été étudié à l'aide d'un Derivatograph et par ATD quantitative. La méthode d'analyse thermique complexe appliquée s'est révélée bien adaptée à l'étude de l'efficacité de l'ignifugation, par comparaison avec les examens effectués en parallèle avec la méthode de l'indice d'oxygène et par dosage de la teneur en phosphore de l'échantillon. Les valeurs de l'efficacité obtenues avec les différentes méthodes sont en corrélation.

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The authors thank Prof. E. Pungor for stimulation of the present work and for discussions.     

Studies on the graft copolymerization of cellulosic materials

Graft copolymers of acrylic acid on cellulosic materials were obtained by use of ceric ion in aqueous medium at various temperatures. The level of incorporation of poly(acrylic acid) grafts and the efficiency of grafting were significantly reduced as the temperature of polymerization was increased from 35° to 60°C. The uptake of cadmium and copperions from aqueous solution by the cellulose-g-poly(acrylic acid) copolymer was examined by equilibrium and dynamic sorption studies. The amount of metal ions removed from solution depended on the metal ion type, initial concentration of the metal ion solution, level of incorporation of poly(acrylic acid) in the graft copolymer and the temperature of the metal ion solution.     

Determination of trace amounts of phosphorus in organic compounds by wickbold combustion

Summary Wickbold combustion in a standard quartz apparatus with a suction burner is suitable for phosphorus determination in acetonesoluble materials if the samples are burned together with an organic halide, e. g. carbon tetrachloride. Probably phosphorus halides are formed which pass through the hot parts of the apparatus fast enough not to react with the quartz walls. The recovery is 95–100% for amounts of phosphorus up to 3.5 mg per combustion.

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Bestimmung von Phosphorspuren in organischen Verbindungen durch Wickbold-Verbrennung

Zusammenfassung Die Wickbold-Verbrennung in einer normalen Quarz-Apparatur mit Saugbrenner ist zur Phosphor-Bestimmung in acetonlöslichen Substanzen geeignet, wenn gleichzeitig mit den Proben eine organische Halogen-Verbindung, z. B. Tetrachlorkohlenstoff, verbrannt wird. Vermutlich werden dabei Phosphorhalogenide gebildet, die die heißen Zonen der Apparatur so schnell passieren, daß keine Reaktion mit den Quarzwänden stattfindet. Die Wiederfindungsrate für Phosphormengen bis 3,5 mg pro Verbrennung beträgt 95–100%.

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Presented at the 8th International Microchemical Symposium, Graz, August 25–30, 1980.     

Magnetic cellulosic materials based on TEMPO-oxidized viscose fibers

A simple method for preparation of magnetic cellulose fibers by coating (2,2,6,6-tetramethylpiperidin-1-yl)oxyl (TEMPO)-oxidized viscose with oleic-acid-coated or uncoated, freshly prepared magnetic nanoparticles (MNp) is presented. MNp attachment was facilitated by chemical activation of the cellulose fibers through introduction of negatively charged carboxylic groups using the well-established TEMPO-mediated oxidation protocol. The resulting composite materials preserved the intrinsic properties of the cellulose fibers, but gained notable specific features due to the presence of magnetic nanoparticles. The obtained composite materials were characterized using spectral (Fourier-transform infrared spectroscopy) and microscopic (scanning electron microscopy) methods. Thermogravimetric analyses were carried out to evaluate the thermal stability of the magnetic fibers. The magnetic properties were evaluated using vibrating-sample magnetometry.     

The mechanism of consumption of ceric salt with cellulosic materials

Efforts were made in the present study to elucidate the mechanism of graft copolymerization of cellulose in the presence of a ceric salt as initiator. When cellulose is treated with an aqueous solution of the ceric salt, ceric ion is consumed in a roughly first-order reaction in the oxidation of cellulose and in the adsorption on cellulose, and the ratio of the rate constants of oxidation and adsorption is about 1:3 in the case of sulfite pulp. Ceric ion is adsorbed so strongly on cellulose as not to be readily desorbed by treatment with water, dilute acid, or dilute alkali. The number of moles of adsorbed ceric ion was approximately equal to the number of moles of the total carbonyl groups in the cases of cotton and sulfite pulp, which are low in hemicellulose content, and was several times as large in the cases of kraft pulp and semichemical pulp, which contain about 22% hemicellulose. In these samples, however, it was interesting to note that the amount of the adsorbed ceric ion was roughly equal to the amount consumed in oxidation. Cellulose on which ceric ion is adsorbed reacts with methyl methacrylate to yield graft copolymers; a higher molecular weight of grafts, smaller number of grafts, and lower graft efficiency than in a standard polymerization were observed. Since the stability of the adsorbed ceric ion is high, a contribution of the adsorbed ceric ion to the graft copolymerization appears small, and the oxidation reaction, which proceeds slightly more slowly than adsorption, seems more important to the graft copolymerization.     

The effect of the presence of volatile organoselenium compounds on the determination of inorganic selenium by hydride generation

As a result of microbiological activity it is possible to find dimethylselenium (DMSe) and dimethyldiselenium (DMDSe) in a wide type of environmental samples, such as soils, sediments, sewage sludges and plants where methylation can take place.Selenium determination by hydride-generation (HG) techniques requires its presence as Se(IV). Consequently, inorganic speciation by hydride generation techniques is done by first determining Se(IV) and then, after reduction of Se (VI) to Se(IV), the total selenium. Therefore, the concentration of Se (VI) is evaluated as the difference between total inorganic selenium and Se(IV). In the present work it could be demonstrated that DMSe and DMDSe are forming other volatile species by reaction with sodium borohydride, applying the same reduction condition as for inorganic selenium. These species are subsequently detected by several atomic techniques (atomic absorption AAS, atomic fluorescence AFS and inductively coupled plasma-mass spectrometry ICP-MS). The error that their presence can cause in determination of inorganic selenium has been evaluated. The magnitude of this error depends on the specific analytical detector used.The coupling of pervaporation-atomic fluorescence is proposed for the identification of these species and pervaporation-gas chromatography-atomic fluorescence for their individual quantification.     

Combination of cellulosic materials and metallic ions

Cellulosic materials (DP, SCP) and PVA fibers were treated with four kinds of metallic ions (Ca²⁺, Fe²⁺, Fe³⁺, Ce⁴⁺), and the adsorption behavior was studied to elucidate the manner in which the celluloses and the metallic ions were combined. The effects of treatment temperature, time, and concentration upon the amount of the metallic ions adsorbed were examined. With Ca²⁺ and Fe²⁺, the effects of such factors on the adsorption were slight, while with Fe³⁺ and Ce⁴⁺ the effects of time, temperature, and ion concentration were pronounced. Also, it was evident that the amount (molar) of equilibrium adsorption of Ca²⁺ or Fe²⁺ was approximately the same as the content of carboxyl groups in the cellulose sample, and the amount of equilibrium adsorption of Fe³⁺ or Ce⁴⁺ was approximately the same as that of total carbonyl group content. When the samples which had adsorbed these metallic ions were treated with 0.1N hydrochloric acid, the Ca²⁺ and Fe²⁺ were completely desorbed while about 80% of the adsorbed Fe³⁺ and Ce⁴⁺ remained. These results indicate that there are two types of combinations of cellulosic materials and metallic ions involved: one is thought to be an ionic bond, while the other is considered to be a chelate bond.     

Dibenzodioxin adsorption on inorganic materials

Dibenzodioxin adsorption/desorption on solid surfaces is an important issue associated with the formation, adsorption, and emission of dioxins. Dibenzodioxin adsorption/desorption behaviors on inorganic materials (amorphous/mesoporous silica, metal oxides, and zeolites) were investigated using in situ FT-IR spectroscopy and thermogravimetric (TG) analysis. Desorption temperatures of adsorbed dibenzodioxin are very different for different kinds of inorganic materials: approximately 200 degrees C for amorphous/mesoporous silica, approximately 230 degrees C for metal oxides, and approximately 450 degrees C for NaY and mordenite zeolites. The adsorption of dibenzodioxin can be grouped into three categories according to the red shifts of the IR band at 1496 cm(-1) of the aromatic ring for the adsorbed dibenzodioxin: a shift of 6 cm(-1) for amorphous/mesoporous silica, a shift of 10 cm(-1) for metal oxides, and a shift of 14 cm(-1) for NaY and mordenite, suggesting that the IR shifts are proposed to associated with the strength of the interaction between adsorbed dibenzodioxin and the inorganic materials. It is proposed that the dibenzodioxin adsorption is mainly via the following three interactions: hydrogen bonding with the surface hydroxyl groups on amorphous/mesoporous silica, complexation with Lewis acid sites on metal oxides, and confinement effect of pores of mordenite and NaY with pore size close to the molecular size of dibenzodioxin.     

Testing the retardancy effect of various inorganic chemicals on smoldering combustion of Pinus halepensis needles

The fire retarding performance of 28 different inorganic chemical substances was tested by measuring the relative particle fire hazard properties of Pinus halepensis needles treated with these chemicals. The tests were performed using a new method, based on a specifically designed apparatus for monitoring the forest species temperature, under precisely controlled temperature and static air atmosphere conditions. The relative ignition and smoldering combustion properties determined were: the ignition delay time, the combustion rate, the heat content and the mass residue of forest samples. The key elements for the effectiveness of fire retardants were the delay of ignition and the reduction of heat and combustion rate. The chemicals examined were: Cu, Fe, Al₂O₃, Fe₂O₃, SiO₂·H₂O, NaHCO₃, KI, KBr, KCl, NaCl, CaCO₃, MnSO₄·5H₂O, CuSO₄·5H₂O, MgCl₂·6H₂O, Na₂B₄O₇·10H₂O, Na₂HPO₄, Na₂CO₃, Na₂SiO₃, ZnSO₄·7H₂O, Zn₃(PO₄)₂·2H₂O, NH₄Br, NH₄Cl, NH₄HCO₃, (NH₄)₂CO₃, NH₄H₂PO₄ (MAP), (NH₄)₂SO₄ (AS), (NH₄)₂HPO₄ (DAP) and a commercial retardant containing both DAP and AS. Among them the best performance was exhibited by ammoniac phosphates, followed by ammoniac sulfates and silica.     

Novel flame retardants containing cyclodextrin nanosponges and phosphorus compounds to enhance EVA combustion properties

A novel flame retardant intumescent system, aimed to improve the fire stability of ethylene vinyl acetate copolymer (EVA), has been prepared by melt blending of the copolymer and a complex of cyclodextrin nanosponge-phosphorus compounds. As compared to traditional systems, this complex, stable in processing conditions, has the advantage that nanosponges act as both carbon sources and foam forming agents while the phosphorus compounds are able to directly generate phosphoric acid in situ. In this context, cyclodextrin nanosponges undergo dehydration in presence of the acid source, generating water vapour and char, and thus protecting the copolymer against combustion. Different acid sources have been investigated in order to reach the optimum interaction with the nanosponges. Raman measurements and thermogravimetric analyses have shown that the cavities of nanosponges entrapped the phosphorus derivatives forming stable complexes at the temperature of EVA processing. Different amounts of these complexes (5, 10 and 15 wt.%) have been added to EVA via melt blending and their flame retardancy properties measured by UL94 test and cone calorimetry. Strongly modified burning kinetics, as compared to the behaviour of the neat copolymer, have been found by UL94 test: V2 classification has been achieved for every formulation regardless of the type and the amount of complex used. EVA combustion behaviour by cone calorimetry has also been significantly affected: the heat release rate decreased dramatically down to ca. 20% in the presence of these new additives.     

Adsorption of organic compounds onto polyelectrolyte immobilized-surfactant aggregates on cellulosic fibers

The adsorption of anionic surfactants with different hydrophobic chain lengths onto cellulose fibers pretreated with a cationic polyelectrolyte has been investigated. Five steps are involved in the adsorption process, which was ascribed to the formation of monolayer and bilayer surfactant aggregates. Electrostatic interaction between the residual surface charges followed by hydrophobic interaction among the alkyl chains are considered the main factors in the adsorption process. The adsorption of the anionic surfactant was found to greatly enhance the retention of organic compounds onto the polyelectrolyte-treated cellulose. The coadsorption phenomenon, which was dependent on the saturation level of the adsorbed surfactant, has been explained in terms of the accumulation of the organic solute on the hydrophobic core generated by the adsorbed layer.     

Desorption reaction of ferric ions adsorbed on cellulosic materials by acids

Factors affecting the desorption reaction of ferric ions adsorbed on cellulose and oxidized poly(vinyl alcohol) fibers by acids were investigated. The desorbing effect generally increased with increasing acid concentration, treating temperature, and treating time, although the magnitude of this effect varied somewhat from one acid to another. Oxalic acid, hydrochloric acid, sulfuric acid, sulfurous acid, and phosphoric acid are examples of those acids which show large desorbing effects. Scission of the cellulose chain was also observed under the desorption conditions used for such acids. The desorption reaction may be divided into two stages, an initial fast reaction and a subsequent slow reaction; the activation energies were calculated for each reaction, and values of 7–10 kcal/mole and 5–6 kcal/mole were obtained for cellulose and oxidized poly(vinyl alcohol) fibers, respectively.     

The separation of inorganic isomeric cis-trans compounds by paper chromatography and the effect of configuration on rf values

It has been established that of all the inorganic isomeric cis–trans compounds that have been separated by paper chromatography up to the present, the cis isomers have higher rf values than the trans, forms On the basis of this regularity, a new method has been suggested for the determination of the configuration of inorganic isomeric cis-trans compounds     

The effect of limestone on the combustion of fuel blends

Combustion profiles of coal-limestone-paper blends were studied using thermogravimetric/ Fourier transform infrared spectroscopy (TG/FTIR). The role of limestone in promoting the initial combustion of coal-paper blends and its ability to absorb sulphur oxides were examined.     

Enzymatic conversion of cellulosic materials to sugars and alcohol

This techno-economic study deals with the production of sugars and alcohols from cellulosic materials. It covers such key subjects as: potential raw materials; the state-of-the-art on production technologies; the economics of extant processes; and finally infers implications for developing countries from the foregoing. It is clear that a large number of cellulose-, starch-, and sugarcontaining plants can be processed to produce sugars and alcohols. Sugar-containing plants such as sugarcane, sweet sorghum, and nipa palm are the best candidates for the high-yield production of alcohol fuel. Likewise, the starch-containing crops such as cassava, sweet potatoes, yams, taro, and tannia are good candidates, but require an additional step to break down starch to sugar. However, the emphasis of this report is on the major part of biomass containing cellulose and which, therefore, needs special treatment before it can be used to produce glucose and alcohols. To utilize cellulosic containing raw materials the following steps are necessary:

1. Growth, harvest, and delivery of raw materials to processing plants; or, alternatively, the collection and delivery of cellulosic “waste” products.
2. Pretreatment or conversion of the raw material by mechanical, physical, chemical, or enzymatic methods to break down the cellulose to sugars and to modify or remove unwanted side-products, usually lignin and hemicellulose.
3. Recovery and purification of sugars from reaction mixture.
4. Fermentation of sugars to alcohol and purification by distillation.
5. Treatment of process residues to reduce pollution and to recover potentially valuable side-products.

From the considerable research and development work carried out in all areas of pretreatment, it appears acid and enzymatic hydrolysis processes hold the most promise for developing countries. Though acid hydrolysis technology is more advanced, greater ultimate potential is seen in the enzymatic hydrolysis, which is, therefore, recommended for developing countries. The economics of producing alcohol from cellulosic materials is at this time not favorable. Nevertheless, it is recommended that further research and development be undertaken in this area in order to accomplish one or more commercially attractive processes for producing alcohol from fermenting cellulose. If this was accomplished, the developing countries could gain in the following manner:

? Increase self-sufficiency since alcohols can to a great part substitute for petroleum fuels.

? Achieve a better balance of trade.

? Be able to increase employment, especially in rural areas.

? Achieve a higher level of technical competence in biotechnology and related areas.

? Be in a position to expand chemical industries.

? Establish an improved agricultural base by being able to utilize alternative crops and by being able to use what was previously termed agricultural wastes.

     

1, 1-dichloroalkylphosphonates: Convenient starting materials for low-coordinated trivalent phosphorus compounds

Diisopropyl 1,1-dichloroalkylphosphonates bearing various groups (alkyl, aryl, allyl, benzyl, phenylthiolate, trimethylsilyl) in the α-position were reduced to the corresponding primary 1,1-dichlorophosphines by the LiAlH₄-AlCl₃ system in diethyl ether. Subsequent dehydrochlorination with tertiary amines in the presence of trapping dipolar compounds (ethyl diazoacetate or n-hexylazide) led to the expected 1,2,4-diazaphospholes or 3H-1,2,3,4-triazaphospholes.     

Biodegradable thermoactive packaging using phase change material particles on cellulosic materials

Cellulose - Environmental concerns about the use of non-renewable raw materials and non-biodegradable waste production have increased exponentially in recent decades. Phase change materials respond...