Amount Of Sodium Carbonate Research Articles

Recovery of Tungsten and Vanadium from Spent Selective Catalytic Reduction Catalysts by Soda Roasting: A Mechanistic Study

This research investigated how soda roasting, which alters the roasting temperature and sodium carbonate concentration, recovers tungsten and vanadium from used selective catalytic reduction (SCR) catalysts. The ideal sodium carbonate content and roasting temperature were determined to be 800 °C and 30 wt%, respectively. Under these circumstances, tungsten and vanadium recoveries were 82.63% and 90.07%, respectively. In order to understand the roasting process, the compositions and morphologies of the original catalyst and specimens after roasting were examined by X-ray diffraction, scanning electron microscopy, and energy dispersive spectroscopy. In addition, the thermodynamic parameters associated with this process were calculated using the HSC 6.0 program to confirm compositional changes during roasting, the result shows that the chemical reactions among vanadium, tungsten, titanium and sulfur with sodium carbonate have priority in this system, as V2O5= SO3> WO3> TiO2; And the phases formation of vanadium and titanium are different at different temperatures and the amount of sodium carbonate, such as Na2V2O6, NaVO3, Na3VO4, VO2, Na2O* TiO2, Na2O* 3TiO2, 4Na2O* 5TiO2, and so on. Therefore, the recovery of vanadium and tungsten is significantly influenced by the other catalyst components as well as the reaction conditions. Based on this combination of experimental study and theoretical calculations, a technique for recovering tungsten and vanadium from spent SCR catalysts by soda roasting is suggested.

Calcite Precipitation at Cement–Bentonite Interface. Part 1: Effect of Carbonate Admixture in Bentonite

Calcium leaching from cementitious materials into bentonite is a key process for the long-term alteration of cement–clay interfaces of engineered barrier systems. Strong chemical gradients between cement and clay drive the precipitation of minerals such as calcium silicate hydrate (C–S–H) and calcite. To analyze the mineralogical and porosity evolution at the cement–clay interface, composite specimens consisting of cement paste and bentonite mixed with various amounts of sodium carbonate were subjected to immersion and chloride migrations tests and were investigated by electron probe micro-analysis (EPMA), thermogravimetry/differential thermal analysis (TG-DTA), and X-ray diffraction (XRD) after 4–20 months of immersion. The results show that adding sodium carbonate to the bentonite enhanced the formation of calcite in the form of a surface layer on the cement paste. This suggests pore clogging at the interface and implies the existence of a threshold amount of carbonate addition above which pore clogging occurs. This is the first of two papers; the accelerated evolution of the samples in the presence of an electrical field is discussed in the second paper.

Effect of acceptor and donor dopants (Na, Y) on the microstructure and dielectric characteristics of high Curie point PZT-modified ceramics

This study describes the preparation of a solid solution of $${\text{Pb}}^{2 + } [({\text{Zr}}_{0.05}^{4 + } ,{\text{Ti}}_{0.95}^{4 + } )_{0.97} ({\text{Al}}_{1/3}^{3 + } ,{\text{Zn}}_{1/2}^{2 + } ,{\text{W}}_{1/3}^{6 + } )_{0.03} ]{\text{O}}_{3}$$ (PZT) based on the mixed oxide method. A different amount of sodium carbonate and yttrium oxide (0.03 at.%, 0.06 at.%, and 0.1 at.%), where the ratio of Na:Y = 1:1 by mole, was added to PZT to investigate the effect of Na and Y co-doping. The ceramic samples were sintered and then subjected to phase identification, physical properties determination, and dielectric properties measurement. It was assumed that, by integrating into the lattice parameters, there is a substitution preference alternation of Y3+ for host cations in the perovskite lattice, while Na+ replaces the A-position of Pb2+ in the lattice. This resulted in more oxygen vacancy being generated in the lattice. PZT–xNY compositions exhibited an obvious anomaly in the temperature dependence of dielectric loss and dielectric permittivity below the phase transition temperature. In addition, it was found that doping of 0.1 at.% Na and Y resulted in a maximum dielectric constant (ec$$\sim 10,400$$) at Curie temperature (~ 749 K) with dissipation factor tan(δ)$$\sim 2.798$$%. Moreover, the diffusivity estimated using the modified Curie–Weiss law obtained at 1 kHz for all compositions showed that the material exhibits a diffuse-type phase.

Influence of Sodium Carbonate Amount on Crystalline Phase and Structure Stability for Doping Nickel Hydroxide

Alpha nickel hydroxide has better performances than commercial beta nickel hydroxide. However, the main defect is that α-phase is difficult to synthesize and easily transformed to β-phase Ni(OH)2 upon aging in a strong alkaline solution. In this study, the Al-Co, Al-Yb, Yb-Co and Al-Yb-Co multiple doping was used respectively. By controlling the amount of sodium carbonate, the α-Ni(OH)2 was prepared by ultrasonic-assisted precipitation. And the influence of sodium carbonate on the crystalline phase and structure stability for alpha nickel hydroxide was studied. The results demonstrate that, with increasing amount, the biphase nickel hydroxide transforms to pure alpha nickel hydroxide gradually, and the structure stability is also improved. When the amount of sodium carbonate is 2 g, the sample still keeps α-Ni(OH)2 after being aged for 30 days, for Al-Yb-Co-Ni(OH)2. And when the amount is less than 2 g, the phase transformations exist in the samples with different extents. These results demonstrated that the amount of sodium carbonate is a critical factor to maintain the structural stability of α-Ni(OH)2.

Innovative environmentally friendly technology for copper(II) hydroxide production

The innovative laboratory procedure for the synthesis of copper(II) hydroxide in the form of the aqueous suspension was developed. The reaction mechanism consists of the reaction between copper(II) sulphate pentahydrate and sodium carbonate by successive ion exchange of carbonate ions with the hydroxide ones in a multistep process. Production of copper(II) carbonate and sodium sulphate by reacting of copper(II) sulphate with sodium carbonate was followed by addition of sodium hydroxide solution whereby the product, copper(II) hydroxide, was obtained by releasing an equimolar amount of sodium carbonate. It was determined that, the equimolar reaction of copper(II) sulphate and sodium hydroxide lead to the maximal reactants exploitation. Sodium phosphate, formed in the final process stage by addition of 10 % phosphoric acid solution, acted as a copper(II) hydroxide stabilizer. High yield of the product was obtained by optimizing the synthesis parameters: reaction time, molar ratio of reactants and the reaction temperature. The obtained product was formulated to obtain a commercial product, which is used as a fungicide and bactericide.

A green one-pot three-component cascade reaction: the synthesis of 2-amino-5,8-dihydro-3H-pyrido[2,3-D]pyrimidin-4-ones in aqueous medium.

A one-pot three-component cascade reaction for the green synthesis of a new class of 2-amino-5,8-dihydro-3H-pyrido[2,3-d]pyrimidin-4-ones was developed from the condensation of aromatic aldehydes with 2,6-diaminopyrimidin-4(3H)-one and acetophenone derivatives or various cyclic ketones in the presence of a catalytic amount of sodium carbonate in a mixture of water and ethanol at 60 [Formula: see text]. This reaction led to the construction of two carbon-carbon bonds and one carbon-nitrogen bond in a single synthetic step.

STUDY OF THE INFLUENCE BETWEEN BARIUM IONS AND CALCIUM IONS ON MORPHOLOGY AND SIZE OF COPRECIPITATION IN MICROEMULSION

In this paper, we systematically drew a series of inverse-microemulsion quasi-ternary system phase diagrams of OP -10+ C8H17OH + C6H12+ brine ( CaCl2/ BaCl2) by adjusting the ratio of CaCl2and BaCl2. On this basis, microemulsions have been prepared with seven different molar ratios of Ca2+/ Ba2+, and calcium carbonate and barium carbonate coprecipitation products were obtained by reaction with an equimolar amount of sodium carbonate. The influence of barium ion to morphology and composition of nanometer calcium carbonate were studied. These samples were characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The SEM photographs indicated that when the content of Ca2+was higher, some incomplete large cube of coprecipitation particles were formed in solution, but with the content of Ba2+increased gradually, they formed a large number of small spherical particles, with the further increase of Ba2+concentration, the particles mainly had structures of irregular polyhedron eventually. The measurement results of FTIR and XRD indicated that CaCO3coprecipitation products gradually changed from calcite to the vaterite, eventually turned into being aragonite with the further increase of Ba2+concentration.

Sphalerite/silica interaction: Zeta potential distribution measurement

An appropriate measurement is needed to control the calcium ion content and reduce the interaction among fine mineral particles. In this paper, the sphalerite/silica interactions were studied by Zeta potential measurements and a novel Zeta potential distribution (ZPD) measurement method in different concentrations of calcium ion solution. To study mineral surface molecular and atomic absorption states, energy dispersive spectroscopy (EDS) and scanning electron microscope (SEM) were used. Flotation reagent adsorbed on the mineral surface was analyzed by the interactions status. The results show that adsorption of flotation reagent is not conducive when the calcium ion concentration is high in the solution. Reducing the calcium ion concentration is the effective method to reduce particle interactions in the pulp. The specific method is that the appropriate amount of sodium carbonate is added into the gypsum-supersaturated solution. The minerals’ interactions can be interpreted by measuring ZPD.

Comparison of methods for distinguishing sodium carbonate activated from natural sodium bentonites

A lot of natural Ca/Mg-bentonites are turned into Na-bentonites. By adding sodium carbonate to a Ca/Mg-bentonite in the presence of some water Na+ enters the interlayer and Ca/Mg-carbonates precipitate outside. Natural Na-bentonites and activated Na-bentonites are rather similar. Therefore, in the present study methods are tested to distinguish both. This is relevant not only for customs but also for research and development. For activation different amounts of sodium carbonate are added. The dosage ranges from a few % of the CEC to slightly above the CEC corresponding to 1–5mass% Na2CO3. Also the water content may vary from the dried state at which the actual activation (cation exchange) does not take place up to the presence of excess water leading to a complete reaction. Altogether four cases had to be considered separately (Na2CO3 above CEC+excess water or dry and Na2CO3 much below the CEC+excess water or dry). If water was absent (cation exchange was not complete) the sodium carbonate phases could be detected by XRD, IR, or with STA–MS measurements. This result was expected but surprisingly, STA–MS–CO2 measurements were found to be applicable even in the most difficult case (sodium carbonate addition below CEC and excess of water=reaction complete). In the case of some samples activated with 2mass% sodium carbonate only, a weak STA–MS–CO2-peak was observed at about 100°C. Unprocessed materials are free of any carbonates which decompose around 100°C. Therefore, this 100°C peak indicates alkaline activation. This method was applied to five real products with unknown activation and two of which were found to be activated. The pH of the activated materials was only slightly higher than that of a natural Na-bentonite. The measured difference of 0.3 pH units is not considered to be sufficient to unambiguously conclude alkaline activation.

Effects of sodium carbonate on the carbothermic reduction of siderite ore with high phosphorus content

Siderite ore with high phosphorus content was reduced isothermally at 1,050° C with pulverized coal and different dosages of sodium carbonate. X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy-dispersive analysis of X-rays (EDAX) were used to characterize the samples. The influence of sodium carbonate on the carbothermic reduction process was investigated. Sodium carbonate and its dosage played a considerable role in the carbothermic reduction. The iron particle size in the reduced ore was below 20 µm, and fayalite was abundant without sodium carbonate additive. With a mass ratio of Na2CO3-to-ore of 5% additive, the iron particle size in the reduced ore was generally above 50 µm, and the diffraction intensity associated with metallic iron in the XRD pattern increased. The effect of sodium carbonate on the phase transformation of fluorapatite during carbothermic reduction was also addressed via thermodynamic calculations and aqueous leaching experiments. The results showed that the fluorapatite was not reduced to P2 at 1,050° C, and a portion of the fluorapatite was converted to soluble phosphate. The reduction of siderite can be catalyzed by adding an appropriate amount of sodium carbonate. This catalytic activity was caused by an increase in the reducing reaction activity of FeO and the acceleration of the carbon gasification reactions. The decrease in phosphorous content in the iron concentrate was attributed to an improvement in the separation of the iron phase from the slag phase when sodium carbonate was added and with the formation of soluble phosphate.

Carbothermic reduction of siderite ore with high phosphorus content reinforced by sodium carbonate

A dressing metallurgy flowsheet, which consists of a sodium salt added reinforced reductive roasting–magnetic separation process, is proposed in this paper for the treatment of siderite ore with high phosphorous content. The sodium salt added reinforcement reductive roast process is accomplished by the addition of an appropriate amount of sodium carbonate, which reacts with SiO2 preventing its counter catalysis on FeO, thereby increasing the reducing reaction activity of FeO and further reinforcing the reduction of siderite. The phosphorus compounds were not reduced in the low temperature reduction process and remained as fluorapatite in the gangue phases. Ultrafine grinding–magnetic separation of magnetic minerals is an efficient way to obtain qualified iron concentrate. It is therefore believed that, with an emphasis on the effect of Na2CO3 and its dosage on the reduction of siderite, the technology proposed in this paper will be of benefit to the exploitation of similar refractory iron ore.Dans cet article, on propose un schéma de procédé de préparation métallurgique, consistant d’un procédé de grillage réductif renforcé d’un sel de sodium ajouté et de séparation magnétique, pour le traitement du minerai de sidérite à haute teneur en phosphore. Le procédé de grillage réductif à renforcement de sel de sodium ajouté est accompli par l’addition d’une quantité appropriée de carbonate de sodium qui réagit avec le SiO2, empêchant sa ‘contre catalyse’ du FeO, augmentant donc l’activité de la réaction de réduction du FeO et renforçant davantage la réduction de la sidérite. Les composés de phosphore n'étaient pas réduits dans le procédé de réduction à basse température et restaient sous forme de fluorapatite dans les phases de gangue. Le broyage utrafin-séparation magnétique des minéraux magnétiques est une manière efficace d’obtenir un concentré qualifié de fer. En portant l’emphase sur l’effet du Na2CO3 et de son dosage sur la réduction de la sidérite, on croit donc que la technologie proposée dans cet article bénéficiera l’exploitation de minerai similaire de fer réfractaire.

Estimation of Micellization Parameters of SDS in the Presence of Some Electrolytes for Emulsion Polymerization Systems

AbstractThe critical micelle concentration and the effective degree of dissociation of micelles (α) of sodium dodecyl sulfate, which is the most extensively used surfactant in emulsion polymerization systems, were determined in the presence of various amounts of sodium carbonate and potassium persulfate, and some monomers, such as methyl methacrylate, butyl acrylate, and styrene by means of the conductometric procedure at 25 °C. In addition, the other micellization parameters, such as aggregation number and number of counter‐ions per micelle, were computed directly from the obtained conductivity measurements data. The effect of the combination of sodium carbonate and potassium persulfate, on the critical micelle concentration of the sodium dodecyl sulfate solutions was studied at 60 °C (emulsion reaction temperature). The empirical formulations derived provide an easy way to estimate the critical micelle concentration and the effective degree of dissociation of micelles of a system at a given electrolyte and monomer concentration.

Evaluation of Sampling Methods for Measuring Exposure to Volatile Inorganic Acids in Workplace Air. Part 2: Sampling Capacity and Breakthrough Tests for Sodium Carbonate-Impregnated Filters

In France, the MétroPol 009 method used to measure workplace exposure to inorganic acids, such as HF, HCl, and HNO3, consists of a closed-face cassette fitted with a prefilter to collect particles, and two sodium carbonate-impregnated filters to collect acid vapor. This method was compared with other European methods during the development of a three-part standard (ISO 21438) on the determination of inorganic acids in workplace air by ion chromatography. Results of this work, presented in a companion paper, led to a need to go deeper into the performance of the MétroPol 009 method regarding evaluation of the breakthrough of the acids, both alone and in mixtures, interference from particulate salts, the amount of sodium carbonate required to impregnate the sampling filter, the influence of sampler components, and so on. Results enabled improvements to be made to the sampling device with respect to the required amount of sodium carbonate to sample high HCl or HNO3 concentrations (500 μL of 5% Na2CO3 on each of two impregnated filters). In addition, a PVC-A filter used as a prefilter in a sampling device showed a propensity to retain HNO3 vapor so a PTFE filter was considered more suitable for use as a prefilter. Neither the material of the sampling cassette (polystyrene or polypropylene) nor the sampling flowrate (1 L/min or 2 L/min) influenced the performance of the sampling device, as a recovery of about 100% was achieved in all experiments for HNO3, HCl, and HF, as well as HNO3+HF and HNO3+HCl mixtures, over a wide range of concentrations. However, this work points to the possibility of interference between an acid and salts of other acids. For instance, interference can occur through interaction of HNO3 with chloride salts: the stronger the acid, the greater the interference. Methods based on impregnated filters are reliable for quantitative recovery of inorganic volatile acids in workplace atmosphere but are valuable only in the absence of interferents.

Detection of Spatial Inhomogeneity in Poly(acrylic acid) Gels by Measuring Time-Dependent Diffusion Coefficients of a Probe in NMR Experiments: Effect of the Degree of Cross-Linking and Degree of Swelling

Inhomogeneities in poly(acrylic acid) (PAA) gels differing in their degree of cross-linking were detected as a function of the degree of swelling, Q, defined as the mass of the swollen gel divided by the mass of the dry polymer, Q = Mswollen/Mdry. Q was in the range 2.8−10.0 for the gels studied. The networks were prepared at 70 °C by simultaneous polymerization and cross-linking of a mixture of acrylic acid (AA), sodium carbonate, cross-linker (1,4-butanediol diacrylate), and the redox couple sodium persulfate/sodium isoascorbate as the initiator. Two types of networks were prepared by using the same monomer concentration (30 wt %) and the same amount of sodium carbonate but different amounts of the cross-linker, 1.1 and 0.5 wt %, respectively, in the monomer mixture. The corresponding notation is GEL1 and GEL2. Detection of heterogeneities was based on measuring the diffusion coefficients of the probe molecule poly(ethylene glycol) (PEG) as a function of the degree of swelling and diffusing time, Δ, by means of field-gradient 1H NMR spectroscopy. The inhomogeneities emerged as the degree of swelling of the gels was reduced. For the highly swollen gels (Q = 10.0 and 5.2 for GEL1 and Q = 10.0 and 5.1 and 4.5 for GEL2) only one diffusion coefficient was detected, independent of the diffusing time, Δ, in the range 30−500 ms. For less swollen gels (Q = 2.9−4.5 for GEL1 and 2.8−3.9 for GEL2) two diffusion coefficients were detected, Dfast and Dslow, with values that depended on Δ; for these less swollen gels the diffusion distances dfast and dslow, and the relative fractions of the fast and slow diffusion components, ffast and fslow, were calculated. We defined a specific degree of swelling, Qs, above which the diffusion of the probe in the two gel systems changed from one to two components. A larger value of Qs in GEL1 was taken as an indicator of a more inhomogeneous gel. Analysis of the effect of Δ on the diffusion coefficients, diffusion distances, and fractions of slow and fast diffusion components indicated that the gels form a highly cross-linked region in a narrow Q range. In this Q range, the polymer chains interact and form a highly restricted diffusion region. The extent and distribution of the cross-links form different restricted diffusion regions in GEL1 and GEL2 systems.

Preparation of superabsorbent polymer with slow‐release phosphate fertilizer

AbstractA superabsorbent polymer with slow‐release phosphate fertilizer was prepared by esterification of polyvinyl alcohol (PVA) and phosphoric acid (H3PO4), which was a slow‐release fertilizer at the same time. The product's water absorbency (WA) was about 480 times its own weight if it was allowed to swell in distilled water at room temperature for 24 h. WA under various conditions, such as varying the reaction time, the amount of sodium carbonate (Na2CO3), the reaction temperature, and the concentration of phosphoric acid ([H3PO4]), were investigated and optimized. The optimal sample of the product was characterized by FTIR and elemental analysis. The results showed that phosphoric groups had grafted on PVA molecule chains, and the content of P2O5 in the product was 31.2%. The water retention property and phosphate slow‐release mechanism of the product were studied as well. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 92: 3417–3421, 2004

Flotation of sodium carbonate and sodium bicarbonate salts from their saturated brines

The flotation behavior of sodium carbonates and sodium bicarbonate has been studied with dodecyl amine hydrochloride (DAH) and sodium dodecyl sulfate (SDS) as part of a research program to evaluate the potential of flotation technology for use in the trona industry. Laboratory microflotation experiments generally show that flotation of sodium carbonate salts is possible at least to some extent with cationic (DAH) and anionic (SDS) collectors if the salt is thermodynamically stable under the prevailing experimental conditions. Anhydrous sodium carbonate does not float at any collector concentration because of its instability at the temperatures considered. Sodium carbonate monohydrate can be floated to completion with DAH and SDS at temperatures higher than 40 °C where it is thermodynamically stable but not at lower temperatures. Sodium carbonate decahydrate is difficult to float (30% yield) even at room temperature where it is thermodynamically stable. Even modest flotation of decahydrate is not possible for temperatures exceeding 32 °C under which conditions the decahydrate salt becomes unstable. In general, the sodium carbonate salts are difficult to float even when they are thermodynamically stable because of their strong water structure making influence.In contrast, strong and complete flotation of sodium bicarbonate can be achieved with both DAH and SDS at all temperatures. Such a flotation response was expected since sodium bicarbonate is stable at these temperatures and since the sodium bicarbonate salt does not promote the formation of water structure. Addition of sodium carbonate to the saturated bicarbonate solution, however, destroys the flotation of sodium bicarbonate completely. It is evident that the amount of sodium carbonate in the saturated solution is a most important parameter which controls the flotation response of sodium bicarbonate.Finally trona, sodium sesquicarbonate, the double salt of sodium carbonate and bicarbonate, was found not to float at room temperature with either the DAH or SDS collectors. These flotation results are discussed with regard to interfacial water structure as influenced by salt properties.

Surface Mediated Organometallic Synthesis: Formation of [H~5Os~1~0(CO)~2~4]^- by Hydrogenation of Silica-Supported [Os(CO)~3(OH)~2]~n as a Springboard for a High-Yield Synthesis of [H~4Os~1~0(CO)~2~4]^2^- Starting from alpha-[Os(CO)~3Cl~2]~2 and Working in Ethylene Glycol Solution

New high yield routes to the high nuclearity hydrido carbonyl clusters [H5Os10(CO)24]- and [H4Os10(CO)24]2-, model systems for the chemisorption of CO and H2 on metal surfaces, are reported. [H5Os10(CO)24]- is obtained in good yields by hydrogenation (1 atm) at 200°C of physisorbed [Os(CO)3(OH)2]n whereas in refluxing ethylene glycol solution, that is less acidic than the silica surface, [H4Os10(CO)24]2- is obtained in high yield starting from [Os(CO)3(OH)2]n or, more conveniently, from α-[Os(CO)3Cl2]2 in the presence of the stoichiometric amount of sodium carbonate. The quantitative equilibrium $$[{\text{H}}_{\text{4}} {\text{Os}}_{{\text{10}}} ({\text{CO}})_{24} ]^{2 - } \mathop {\underset { + {\text{H}}^{\text{ + }} } \leftrightarrows }\limits^{ + {\text{OH}}^ - } {\text{ }}[{\text{H}}_{\text{5}} {\text{Os}}_{{\text{10}}} ({\text{CO}})_{24} ]^ -$$ is confirmed.

Dephosphorization of high-phosphorous manganese ores from Andhra Pradesh and southern Orissa, India, by roasting

Because conventional (physical) methods of ore dressing are not suitable for reducing the phosphorus contents of high-phosphorous manganese ores from Andhra Pradesh (AP) and the adjoining area in southern Orissa, India, the adoption of chemical methods becomes imperative. An attempt was therefore made to reduce the phosphorus content of partially beneficiated manganese ores from AP by roasting with sodium carbonate and then leaching with hot water. However, due to the higher phosphorus contents of the manganese ores from Nishikhal mines in southern Orissa, and because of their apparent resistance to dephosphorization by roasting with Na2CO3 alone, a mixture of Na2CO3 and NaCl was found to be necessary to reduce the phosphorus content to below 0.15%. Free-energy calculations at 700°C and above indicated that Na2CO3 (or Na2O as the active component) is a more active reagent than NaCl. Various process parameters, such as the temperature and time of roasting, the amount of sodium carbonate and the temperature and time of leaching, were studied to arrive at the optimum conditions for dephosphorization.

Alkoxide-catalysed hydrolyses of a chlorotriazine in alcohol–water mixtures. A new indirect probe for hydroxide-catalysed hydrolysis

Pseudo-first order rate constants (kobs) and product ratios are reported for competing hydrolyses and alcoholyses of the reactive dichlorotriazine dye (2) in water containing small amounts (usually <0.05 M) of added alcohols (methanol, propan-1-ol, and four polyols: α- or β-methylglucopyranoside, mannitol or sorbitol) at pH 11.2. Additional data are reported in the presence of ethane-1,2-diol, prop-2-yn-1-ol and 2,2,2-trifluoroethanol. Dissection of kobs for solvolysis of the dye (DX) into the separate contributions from hydrolysis (kDOH) and alcoholysis (kDOR) shows that kDOH increases in polyol–water mixtures for 2, but not for the monofluorotriazine (1), and kDOH also increases for 2 in aqueous trifluoroethanol. The results are consistent with alkoxide-catalysed hydrolysis for 2, but with an uncatalysed or weakly-catalysed hydrolysis for 1, and provide indirect support for the possibility of a third order process in which hydroxide could act as a base catalyst. Additional kinetic data for 2 in methanol–water mixtures, containing both sodium carbonate and tetraalkylammonium salts, show rate enhancements particularly when the amount of sodium carbonate is low.

Catalysis of coal gasification by Na lignosulfonate

Steam gasification of a model coke was conducted under various experimental conditions using a specially designed thermogravimetric analyser. The reactivity of a heat-treated German hard-coal char was determined in the range 973–1173 K. The char was also loaded with different amounts of sodium lignosulfonate by an incipient wetting technique, and the reactivity was measured under identical conditions. The sodium lignosulfonate enhanced the gasification rate considerably. The reactivity was even higher than that of char samples loaded with corresponding amounts of sodium carbonate. Sodium lignosulfonate is a more efficient catalyst in the range 973–1023 K, and this can be attributed to its better dispersion throughout the carbon matrix. Its higher efficiency coupled with its low cost qualifies sodium lignosulfonate as a highly suitable catalyst for any low-temperature allothermal gasification process.