Sulfuric Acid Salts Research Articles

Mechanical and durability performance of 100% recycled aggregate concrete pavers made by compression casting

Sustainable infrastructure developments require optimal use of natural resources and the recycling of the materials generated at the end of the service life of concrete structures. Construction and Demolition (C&D) waste in the form of Recycled Concrete Aggregates (RCA) has been used to manufacture structural and non-structural concrete which is known as Recycled Aggregate Concrete (RAC). However, not all the C&D waste could be incorporated into the structural concrete and the development of innovative construction products for the efficient and economic utilization of RCA is still under investigation. This study aimed to produce concrete pavers with 100% recycled aggregates and a minimum amount of cement through Compression Casting Technique (CCT). A comprehensive experimental investigation was carried out to find out the optimum values of fine to coarse aggregate ratio, cement contents, and casting pressure for the concrete pavers so that a minimum target compressive strength of 35 MPa at 7-days is achieved. The concrete mixes with fine and coarse aggregate contents of 60% and 40%, respectively, cement contents of 15% and 20%, and casting pressure of 20 MPa were found to be the most economical and feasible to produce concrete pavers exhibiting the target compressive strength. The mechanical (i.e., compressive and flexural strength) as well as durability (i.e., drying shrinkage, water absorption, cyclic ponding in sulfuric acid and sodium chloride salt solution) properties were investigated in detail for the pavers made from the selected optimum concrete mixes. The compressive and flexural strength of RAC pavers satisfied the minimum required strength values specified in international standards [GB – 28 635–2012, IS 15658:2021, A231.2–14, ASTM C936, ASTM C 1272, ASTM C902] and local [NHA & AJK] specification. The durability tests showed that the RAC pavers are resilient against salt and acid attack. The porous nature of RAC positively affected the pavers’ compressive strength, especially under a saline environment. The maximum water absorption of the RAC pavers was 6.34% which was found to be in the acceptable range, however, their drying shrinkage was higher than Natural Aggregate Concrete (NAC) pavers. As for the impact of casting technique, the properties of the RAC pavers were improved by employing CCT. To predict compressive strength based on the parameters of this study, an equation is proposed by regression analysis of the obtained compressive strength results which showed reasonable accuracy in predicting the strength of pavers. Finally, this study concluded that it is feasible and reliable to manufacture concrete pavers of 35 MPa compressive strength at 7-days (or 55 MPa at 28-days) by replacing 100% natural aggregates with recycled aggregates (both fine and coarse), using 20% cement content, and employing compression casting.

TO THE STUDY OF THE FLOCCULATION AND COAGULATION PROCESS IN THE PURIFICATION OF WATER FOR INDUSTRIAL APPLICATION

It is an important criterion the choice of lighting technique for industrial applications in water purification. In the article it was examined the research methods of the coagulation and flocculation process. Today, the improvement of these techniques and the use of flocculants and coagulants, which speed up the process of coagulation and flocculation, are relevant. It were considered as coagulants sulfuric acid salts Al2(SO4)3 and FeSO4. It was noted an advantage over aluminum salts since iron salts which can be used to purify water with different salt composition and different pH values, which work better at low temperatures, and are characterized by greater strength and grain size. It was considered the application and influence of the cationic flocculant “PuroFloc 890” or the anionic “Flopam”, which allow water clarification without the use of a coagulant. It was determined and considered the process of coagulant formation. Methods and processes for the intensification of the separation process have been studied, including due to the thickening of particles in the aggregate under the action of coagulants and flocculants (coagulants), separation of the liquid and solid phases. It was found that the advantage of the resulting suspended layer is that it works like a filter, removing fine particles from the water. As the particles accumulate, their concentration increases and the phenomenon of compressed deposition occurs, in which the deposition rate decreases because energy was spent on friction. It is necessary to reduce the speed of the upward flow to reduce the productivity of the illuminator,

A Comparative Study of the Synthesis and Hydrolysis of sym-Triaminobenzene Homologues

Here, we investigated the synthetic processes for the methyl derivatives of sym-triaminobenzene and phloroglucinol, the essential chemical reactants coming into use in the production of dyes and pigments, and medicinal drugs for different purposes. The most eco-benign process for the synthesis of triamino derivatives involves the catalytic hydrogenation of corresponding nitroarenes. The present study investigated the hydrogenation of 2,4,6-trinitrotoluene, 2,4,6-trinitroxylene, and 2,4,6-trinitromesitylene over a Pd catalyst. A 1% Pd/Sibunit catalyst was found to be preferable to the 5% analogue with a preserved palladium loading because it shortens the reaction time and provides a higher yield of the target product. The hydrogenation in methanol (or mixed methanol/toluene) at 50-55 °C and 0.5 MPa pressure produced 2,4,6-triaminotoluene, 2,4,6-triaminoxylene, and 2,4,6-triaminomesitylene, which were isolated as sulfuric acid salts in 98, 91, and 97% yields, respectively. The hydrolysis process of the resultant salts was examined, and conditions leading to mono-, di-, and trimethyl derivatives of phloroglucinol (90, 77, and 82%, respectively,) were identified. The hydrogenation of the trinitrobenzene homologues in mixed 7:1 (v/v) acetone/water, followed by hydrolysis to the respective polyphenols, was explored. A successful result was achieved only for 2,4,6-trinitrotoluene. The catalyst activity was shown to decline negligibly throughout 10 cycles of reuse. 2-Methylphloroglucinol was synthesized in a high yield ranging from 85 to 91% calculated as 2,4,6-trinitrotoluene.

Selective turn-on fluorescence detection of formaldehyde in the gas phase

Reliable detection of formaldehyde in gas phase still remains a challenge regarding either sensitivity or selectivity or both. In this study we report on a simple, unique sensor composite, which enables efficient detection of gaseous formaldehyde with both low limit of detection (LOD) and extremely high selectivity. The primary components of the sensor composite include a hydroxylamine sulfuric acid salt ((NH2OH)2·H2SO4) and a fluorescence turn-on probe, which both are coated within the porous matrix of a cellulose plate. The fluorescence probe is based on a perylene diimide (PDI) molecule modified with an aniline group, which is non-fluorescent in its pristine state due to the photoinduced intramolecular electron transfer. Upon interaction with formaldehyde, the hydroxylamine salt will be converted to the corresponding Schiff base through aldimine condensation, releasing the sulfuric acid. The acid released will protonate the aniline group on PDI, resulting in a quick fluorescence turn-on. By measuring the fluorescence increase we can detect formaldehyde both quantitatively and specifically. Under the optimized condition, the sensor demonstrated a LOD of 3.7 ppb, which is much lower than the air quality threshold set by WHO. The sensor was also proven highly selective towards formaldehyde, with negligible response towards other common chemicals. The work reported will not only provide a new sensor for formaldehyde, but moreover open a unique design pathway for sensor composite that combines reactive components with various fluorescence indicators so as to enable highly efficient detection of many other air pollutants and toxic chemicals.

Application and Development of Selective Catalytic Reduction Technology for Marine Low-Speed Diesel Engine: Trade-Off among High Sulfur Fuel, High Thermal Efficiency, and Low Pollution Emission

In recent years, the International Maritime Organization (IMO), Europe, and the United States and other countries have set up different emission control areas (ECA) for ship exhaust pollutants to enforce more stringent pollutant emission regulations. In order to meet the current IMO Tier III emission regulations, an after-treatment device must be installed in the exhaust system of the ship power plant to reduce the ship NOx emissions. At present, selective catalytic reduction technology (SCR) is one of the main technical routes to resolve excess NOx emissions of marine diesel engines, and is the only NOx emission reduction technology recognized by the IMO that can be used for various ship engines. Compared with the conventional low-pressure SCR system, the high-pressure SCR system can be applied to low-speed marine diesel engines that burn inferior fuels, but its working conditions are relatively harsh, and it can be susceptible to operational problems such as sulfuric acid corrosion, salt blockage, and switching delay during the actual ship tests and ship applications. Therefore, it is necessary to improve the design method and matching strategy of the high-pressure SCR system to achieve a more efficient and reliable operation. This article summarizes the technical characteristics and application problems of marine diesel engine SCR systems in detail, tracks the development trend of the catalytic reaction mechanism, engine tuning, and control strategy under high sulfur exhaust gas conditions. Results showed that low temperature is an important reason for the formation of ammonium nitrate, ammonium sulfate, and other deposits. Additionally, the formed deposits will directly affect the working performance of the SCR systems. The development of SCR technology for marine low-speed engines should be the compromise solution under the requirements of high sulfur fuel, high thermal efficiency, and low pollution emissions. Under the dual restrictions of high sulfur fuel and low exhaust temperature, the low-speed diesel engine SCR systems will inevitably sacrifice part of the engine economy to obtain higher denitrification efficiency and operational reliability.

Paper-Based Vapor Detection of Formaldehyde: Colorimetric Sensing with High Sensitivity

We report on a novel colorimetric sensor system for highly sensitive detection of formaldehyde (FA) in the gas phase. The sensor is constructed with paper towel as a substrate coated with the sulfuric acid salt of hydroxylamine ((NH2OH)2·H2SO4) together with two pH indicators, bromophenol blue and thymol blue. Upon exposure to FA, the hydroxylamine will react with the absorbed FA to form a Schiff base (H2C=N-OH), thus releasing a stoichiometric amount of sulfuric acid, which in turn induces a color change of the pH indicator. Such a color change was significantly enriched by incorporating two pH indicators in the system. With the optimized molar ratio of the two pH indicators, the color change (from brown to yellow, and to red) could become so dramatic as to be visible to the eye depending on the concentration of FA. In particular, under 80 ppb of FA (the air quality threshold set by WHO) the color of the sensor substrate changes from brown to yellow, which can even be envisioned clearly by the naked eyes. By using a color reader, the observed color change can be measured quantitatively as a function of the vapor concentration of FA, which produces a linear relationship as fitted with the data points. This helps estimate the limit of detection (LOD), to be 10 ppb under an exposure time of 10 min, which is much lower than the air quality threshold set by WHO. The reported sensor also demonstrates high selectivity towards FA with no color change observed when exposed to other common chemicals, including solvents and volatile organic compounds. With its high sensitivity and selectivity, the proposed paper-based colorimetric sensor thus developed can potentially be employed as a low-cost and disposable detection kit that may find broad application in detecting FA in indoor air and many other environments.

A predictive model for salt nanoparticle formation using heterodimer stability calculations

Abstract. Acid–base clusters and stable salt formation are critical drivers of new particle formation events in the atmosphere. In this study, we explore salt heterodimer (a cluster of one acid and one base) stability as a function of gas-phase acidity, aqueous-phase acidity, heterodimer proton transference, vapor pressure, dipole moment and polarizability for salts comprised of sulfuric acid, methanesulfonic acid and nitric acid with nine bases. The best predictor of heterodimer stability was found to be gas-phase acidity. We then analyzed the relationship between heterodimer stability and J4×4, the theoretically predicted formation rate of a four-acid, four-base cluster, for sulfuric acid salts over a range of monomer concentrations from 105 to 109 molec cm−3 and temperatures from 248 to 348 K and found that heterodimer stability forms a lognormal relationship with J4×4. However, temperature and concentration effects made it difficult to form a predictive expression of J4×4. In order to reduce those effects, heterodimer concentration was calculated from heterodimer stability and yielded an expression for predicting J4×4 for any salt, given approximately equal acid and base monomer concentrations and knowledge of monomer concentration and temperature. This parameterization was tested for the sulfuric acid–ammonia system by comparing the predicted values to experimental data and was found to be accurate within 2 orders of magnitude. We show that one can create a simple parameterization that incorporates the dependence on temperature and monomer concentration on J4×4 by defining a new term that we call the normalized heterodimer concentration, Φ. A plot of J4×4 vs. Φ collapses to a single monotonic curve for weak sulfate salts (difference in gas-phase acidity >95 kcal mol−1) and can be used to accurately estimate J4×4 within 2 orders of magnitude in atmospheric models.

Solid acid carbon catalysts for sustainable production of biofuel enhancers via transesterification of glycerol with ethyl acetate

SO3H-bearing carbons prepared from sugars or glycerol were used as catalysts for the production of acetins via a transesterification route. Two methods of preparation of functionalized carbon catalysts were compared: a) an energy-efficient, one-pot synthesis including partial carbonization of precursors with H2SO4 coupled with simultaneous in-situ functionalization and b) a two-step method including template synthesis of carbon followed by functionalization of the obtained product with sulfuric acid or diazonium salt. The synthesized carbons were used in an eco-friendly process of glycerol transesterification with ethyl acetate under different reaction conditions. All the prepared samples were found to effectively catalyze the reaction, producing a mixture of mono-, di- and triacetins (MA, DA and TA, respectively); however, the efficient production of the target compounds, namely DA and TA, which are valuable biofuel additives, was found to be strongly dependent on the content of sulfonic groups on the surface of these catalysts. A direct correlation between –SO3H concentration and glycerol conversion, as well as the yield of higher esters was established. Moreover, the applied method of one-pot combined partial carbonization and functionalization with H2SO4 was shown to be a convenient way to obtain carbonaceous solid acid catalysts that can be used as promising alternatives to modified carbons produced by conventional two-step techniques.

Electrodialysis concentration of sulfuric acid

An urgent task is the development of new resource-saving technologies for deep processing of wastes from the hydrometallurgical industry for the purpose of their reuse. Membrane technologies make it possible to create closed technological cycles with the reuse of recovered components in production, which allows solving many environmental problems. At the Abinsk Electric Steel Works Ltd. (Russia), during the production of copper-coated steel wire, a large amount of waste containing sulfuric acid and heavy metal salts is generated. The chemical treatment of such effluents with slaked lime and alkali produces a large amount of sludge, which causes environmental problems and leads to the irreversible loss of sulfuric acid. The problem of separating acids and salts can be solved using diffusion dialysis through anion-exchange membranes, however, to return the acid to the production cycle, the purified acid must be additionally concentrated. In this work, we studied the process of electrodialysis concentration of sulfuric acid using heterogeneous ion-exchange membranes Ralex® CMHPP and Ralex® AMHPP (manufactured by MEGA a.s., Czech Republic) which have a polypropylene reinforcing mesh resistant to acids. The main parameters of the electrodialysis concentration process have been determined – the dependence of the concentration of the regenerated sulfuric acid on the concentration at the inlet to the electrodialysis cell and on the current density, as well as the energy consumption for the process. It is shown that with the help of electrodialysis concentration it is possible to obtain sulfuric acid with a concentration of up to 180 g/L, which makes it possible to return it to the production cycle.

Utilization of coffee pulp waste for rapid recovery of pectin and polyphenols for sustainable material recycle

Coffee pulp is one of the major underutilized byproduct of coffee processing in farm level. Disposal of this agro-industrial waste has become one of the most challenging tasks for coffee planters. However, most of the efforts are towards the management of coffee pulp as an effluent, and not-on re-use. The problem is compounded due to the large volumes produced in diluted forms, which makes it expensive to reuse. The preliminary proximate analysis of coffee pulp indicated it to be rich in pectin and polyphenols. The efficacy of various chemicals like ethanol, sulfuric acid, hydrochloric acid, nitric acid, ammonium oxalate and metal salts for effective precipitation of pectin from coffee pulp was evaluated. HPLC characterization of the extracted and concentrated polyphenols fractions was analyzed. The maximum extraction of pectin was achieved by using metal salts and ethanol with 6.0% and 6.7% on wet weight basis respectively. The equivalent weight of extracted pectin (1180.5 mg/g) was found to be higher than that of commercial pectin (724.8 mg/g). The methoxyl content of the commercial pectin and crude pectin were 9.3 and 5.6% respectively. Gallic, vanillin, catechin, ethyl catechol, coumaric, Caffeic, and ferulic acid were the major polyphenols as quantified by the HPLC. The polyphenol fraction showed a good antioxidant activity with phosphomolybdate, FRAP, DPPH, and ABTS radicals respectively. The sustainable utilization of coffee pulp as a source of pectin and polyphenols with good antioxidant activities could help to solve the problem of waste generated in coffee processing in farm level.

Change of quality indexes of premixes in the storage process

The analysis of literature sources shows that the type and material from which the packaging is made has an important place in the system of factors which influence on the storage of feed products and also prevents reducing the quality of raw materials and finished products. Therefore, the purpose of our research is the technological justification of changing the quality indexes of premix samples with salts of trace elements of different chemical nature in the process of storage. For the solution of the tasks, common zootechnical and statistical methods of the research were used. The use of premixes in feeding pigs is based on the fact that they should be used taking into account the biogeochemical properties of the region for which they are calculated. Foods depending on regional properties have a special biochemical composition and excess or lack of individual substances should be offset by the composition of premix. Ignoring this provision necessarily leads to the inappropriate use of BAR, the misbalance of the diet in relation to the physiological needs and inefficiency of the industry. In turn, it requires the purchase and conservation of products for the period of use. Various chemical structures and structures of BAR during the storage process react differently and change qualitative indexes, which leads to a decrease in the productive activity of active substances. It was determined that the humidity of premixes varied within the limits of 12.0-13.0 %, which exceeded the normative, but was not critical, the highest acidity had premix with sulfuric acid salts (6.9 units), the least - premix with lysates (5.7 unit). According to the results of the study, positive qualitative responses were found for the presence of vitamins A, D and B2, macro- and micronutrients: potassium, magnesium, copper, zinc, cobalt, iodine. The above facts of changes in the properties of premixes in the process of storage must be taken into account when providing technological bases for feeding pigs in order to obtain high gains and the quality of manufactured products. Key words: premix, micro-and macro elements, combined fodders, fodder mixes, chelating compounds, feeding, using, pigs' livestock.

Surface composition and properties of Ganymede: Updates from ground-based observations with the near-infrared imaging spectrometer SINFONI/VLT/ESO

Ganymede's surface exhibits great geological diversity, with old dark terrains, expressed through the surface composition, which is known to be dominated by two constituents: H2O-ice and an unidentified darkening agent. In this paper, new investigations of the composition of Ganymede's surface at global scale are presented. The analyses are derived from the linear spectral modeling of a high spectral resolution dataset, acquired with the near-infrared (1.40–2.50 μm) ground-based integral field spectrometer SINFONI (SINgle Faint Object Near-IR Investigation) of the Very Large Telescope (VLT hereafter) located in Chile. We show that, unlike the neighboring moon Europa, photometric corrections cannot be performed using a simple Lambertian model. However, we find that the Oren-Nayar (1994) model, generalizing the Lambert's law for rough surfaces, produces excellent results. Spectral modeling confirms that Ganymede's surface composition is dominated by H2O-ice, which is predominantly crystalline, as well as a darkening agent, but it also clearly highlights the necessity of secondary species to better fit the measurements: sulfuric acid hydrate and salts, likely sulfates and chlorinated. A latitudinal gradient and a hemispherical dichotomy are the strongest spatial patterns observed for the darkening agent, the H2O-ice, and the sulfuric acid: the darkening agent is by far the major compound at the equator and mid-latitudes (≤ ± 35°N), especially on the trailing hemisphere, while the H2O-ice and the sulfuric acid are mostly located at high latitudes and on the leading hemisphere. This anti-correlation is likely a consequence of the bombardment of the constituents in the Jovian magnetosphere which are much more intense at latitudes higher than ±35°N. Furthermore, the modeling confirms that polar caps are enriched in small, fresh, H2O-ice grains (i.e. ≤50 μm) while equatorial regions are mostly composed of larger grains (i.e. ≥200 μm, up to 1 mm). Finally, the spatial distribution of the salts is neither related to the Jovian magnetospheric bombardment nor the craters. These species are mostly detected on bright grooved terrains surrounding darker areas. Endogenous processes, such as freezing of upwelling fluids going through the ice shell, may explain this distribution. In addition, a small spectral residue that might be related to brines and/or hydrated silica-bearing minerals are located in the same areas.

Discovery of conolidine derivative DS39201083 as a potent novel analgesic without mu opioid agonist activity.

We discovered a novel compound, 5-methyl-1,4,5,7-tetrahydro-2,5-ethanoazocino[4,3-b]indol-6(3H)-one sulfuric acid salt (DS39201083), which was formed by derivatization of a natural product, conolidine. DS39201083 had a unique bicyclic skeleton and was a more potent analgesic than conolidine, as revealed in the acetic acid-induced writhing test and formalin test in ddY mice. The compound showed no agonist activity at the mu opioid receptor.

Comparative methods for reduction and sulfonation of graphene oxide for fuel cell electrode applications

Abstract Graphene oxide (GO) was synthetized, reduced and further sulfonated for the preparation of electrodes. GO was obtained using modified Hummer's method from graphite flakes. The partial reduction of graphene oxide (rGO) was performed by chemical and thermal process and subsequently functionalized using sulfuric acid or aryl diazonium salt of sulfanilic acid as sulfonating agents to afford rGO-SO3H. The influence of the reduction processes on the sulfonation reactions of rGO was evaluated through XRD, TGA, FT-IR and Raman techniques. Electrochemical properties of both rGO and sulfonated rGO materials as modified glassy carbon electrode were evaluated using a K3FeCN6 solution as a reference redox system. XRD confirmed the partial reduction of GO by two methods and FT-IR demonstrated that SO3H groups were successfully grafted on GO. VC results confirmed that both reduction and sulfonated methods leads to a better material with superior electrochemical properties compared to GO and rGO. Thermally reduced GO and functionalized with sulfuric acid [rGOT-SO3H(1)] showed the best electron transfer activity compared to those chemically reduced or sulfonated with sulfanilic acid. The electrochemical properties observed for rGOT-SO3H(1) suggest than can be a suitable support material of nanoparticles for the preparation of electrodes for fuel cells applications.

Sulfonation of Graphene Oxide for Fuel Cells Electrode and Membrane Applications

Graphene oxide (GO) and reduced graphene oxide (rGO) have been widely used for high capacity energy conversion and storage in fuel cells and lithium ion batteries, respectively. Particularly, for proton exchange membrane fuel cells (PEMFC) applications the incorporation of sulfonic acid functional groups (-SO3H) into GO/rGO structure has emerged as a powerful strategy to produce promising new support of noble catalysts and ionomer materials, due to a significant increase in the hydrophilicity of rGO improving the nano-catalyst dispersion and ion-exchange capacity (IEC). In this study, GO was synthesized and sulfonated (sGO) for the development of electrodes and membranes. GO was obtained by a modified Hummer’s method from graphite powder, thermally reduced and sulfonated by means of two sulfonating agents: sulfuric acid and aryl diazonium salt of sulfanilic acid. The influence of the sulfonation agents on the physicochemical properties of rGO-SO3H was evaluated through XRD, TGA, FT-IR and Raman techniques. Electrochemical behavior of both materials as modified glassy carbon electrode was investigated in K3FeCN6 solution as a reference redox system. The results demonstrated that the sulfonated materials have superior electron transfer activity and electrochemical properties compared to GO. In addition, the IEC for a commercial membrane modified with rGO-SO3H improved significantly.

Effects of aging on the yielding behaviour of acid and salt induced Laponite gels

The synthetic clay Laponite, when dispersed in water, shows rich phase behaviour that depends on both clay and ionic concentrations. The flow properties of this clay dispersion can be tuned by incorporating different additives such as acid and salt. In this work, we use rheology to study the mechanical properties of Laponite gels when prepared by adding sulfuric acid (H2SO4) and common salt (NaCl). The acid induced Laponite gels form a visco-elastic solid with increasing idle time, while the salt induced Laponite gel transforms to a soft solid almost immediately after sample preparation. Furthermore, in the acid induced Laponite gels, a nonmonotonic evolution of yield stress with idle time is observed. No such observation is evident for the salt induced Laponite gels. These observations are connected to the underlying morphology of the sample which is governed by the osmotic pressure driven aging behaviour of the suspensions. We use cryogenic scanning electron microscopy images for a qualitative understanding of the gel morphologies which we relate to the acquired rheological data. The aging dynamics and the subsequent structural evolution of the sample are further verified by performing a UV–Vis spectroscopy study and found to be in agreement with the rheological and Cryo-SEM experiments.

Extraction and reaction mechanism of potassium from associated phosphorus and potassium ore

Potassium and phosphate were extracted at low temperature by acid hydrolysis process to decompose a new type of associated phosphorus and potassium ore. The main factors affecting the dissolution rate were investigated, such as grinding fineness, the amount of sulfuric acid and fluoride salt, reaction time and temperature, etc. Meanwhile, the effects of various factors on the formation of soluble potassium and phosphate were also discussed. The reaction products and residues were determined by X-ray diffraction (XRD), scanning electron microscopic (SEM) analysis and other means. The results showed that the dissolution rates of potassium and phosphorus were 70wt% and 93.7wt%, respectively, under the conditions of a grain size of 95.64wt% lessthan 0.074 mm, 9.78 g•g-1 sulfuric acid, 0.5 g•g-1 ammonium fluoride, 160 °C and a reaction time of 2 h. The thermodynamic and chemical reaction mechanism was revealed that the primary reaction could be completed spontaneously in a temperature range of 298-433 K. The increase of reaction temperature had an important influence on ion exchange reaction, which was more conducive to the spontaneous process. The research will open up a new way for efficient use of potassium ore resources.

Production of furfural from xylose at atmospheric pressure by dilute sulfuric acid and inorganic salts

In this paper, the dehydration of xylose to furfural was carried out under atmospheric pressure and at the boiling temperature of a biphasic mixture of toluene and an aqueous solution of xylose, with sulfuric acid as catalyst plus an inorganic salt (NaCl or FeCl3) as promoter. The best yield of furfural was 83% under the following conditions: 150mL of toluene and 10mL of aqueous solution of 10% xylose (w/w), 10% H2SO4 (w/w), 2.4g NaCl , and heating for 5h. FeCl3 as promoter was found to be more efficient than NaCl. The addition of DMSO to the aqueous phase in the absence of an inorganic salt was shown to improve the yield of furfural.

Graft polymerization of acrylic acid and methacrylic acid onto poly(vinylidene fluoride) powder in presence of metallic salt and sulfuric acid

Poly(vinylidene fluoride) (PVDF) powder was grafted with acrylic acid (AAc) or methacrylic acid (MAA) by the pre-irradiation induced graft polymerization technique. The presence of graft chains was proven by FT-IR spectroscopy. The degree of grafting (DG) was calculated by the acid–base back titration method. The synergistic effect of acid and Mohr's salt on the grafting kinetics was examined. The results indicated that adding sulfuric acid and Mohr's salt simultaneously in AAc or MAA solutions led to a strong enhancement in the degree of grafting. The grafted PVDF powder was cast into microfiltration (MF) membranes using the phase inversion method and some properties of the obtained MF membranes were characterized.

Phase Behaviour of Ices and Hydrates

The primary volatile ‘rock-forming’ minerals in the icy satellites of the outer solar system include water-ice and various hydrated crystals of methane and ammonia. The rich polymorphism of these substances as a function of pressure and temperature are described in this chapter. This polymorphism has a fundamental influence on the exchange of mass and energy between the core and the surface of icy satellites. We describe the current state-of-the-art in our understanding of the high pressure phase behaviour and the measurements of thermoelastic and transport properties of these substances. In addition we describe the structures and properties of hydrated phases of methanol, sulfuric acid, and various sulfate salts.