Solubilities of calcium and zinc lactate in water and water-ethanol mixture

The solubility of lactate salts, L(+) and DL(±) forms of calcium and zinc lactate in water at temperature between 5 and 80 ‡C, was measured and empirical equations were obtained by regression of solubility-temperature data. The equations can be used to calculate the solubility of calcium and zinc lactate at a given temperature. The change in solubility of L(+) and DL(±) calcium and zinc lactate in water-ethanol mixture at 20 ‡C was also investigated. The solubilities of calcium and zinc lactate were lowered by the addition of ethanol to the solution.     

Efficient adsorption and in-situ ceramics immobilization of simulated trivalent actinides (Nd) by amino-functionalized mesoporous zirconia-silica

It is of great significance to develop a kind of adsorbent which can adsorb and in-situ immobilize radionuclides from aqueous solution. Herein, new amino-functionalized mesoporous zirconia-silica (ZNSi) composites were prepared and applied to adsorb and in-situ immobilize the simulated trivalent actinides (Nd) from aqueous solution. The obtained ZNSi composites exhibited high Nd adsorption capacity (31.14 mg/g) owing to the formation of Nd(OH)₃ via the reaction between Nd³⁺ and OH⁻ derived from the protonation of amino groups. The spent adsorbents with adsorbed Nd³⁺ were successfully changed to stable ZrSiO₄-based glass ceramics by simple sintering treatment. The ZrO₂ and Nd contents had great effect on the phase composition, microstructure evolution and aqueous stability of the obtained ZrSiO₄-based glass ceramics waste forms. The immobilized Nd showed excellent aqueous stability (10⁻⁷ g m⁻² d⁻¹) due to the crystal lattice immobilization of ZrSiO₄. Owing to the efficient adsorption and in-situ immobilization ability, the obtained ZNSi could be potential materials for radioactive wastewater treatment.     

Solubilities of chlormezanone,metaxalone and methocarbamol in supercritical carbon dioxide

The solubilities of three active pharmaceutical ingredients (APIs) in supercritical carbon dioxide were measured in this study using a semi-flow apparatus. These APIs are chlormezanone (C₁₁H₁₂ClNO₃S), metaxalone (C₁₂H₁₅NO₃) and methocarbamol (C₁₁H₁₅NO₅) that are all used as skeletal muscle relaxants. The solubility data are reported for three isotherms at 308.2, 318.2 and 328.2 K, with the pressure range from 12 to 24 MPa. Most solubility data are within the range of 10⁻⁶ to 10⁻⁴ mole fraction for each API. The crossover phenomena were observed from the experimental results for all three systems. These solubility data satisfied the thermodynamic consistency tests. They were then correlated using three semi-empirical models. With the optimally fitted binary interaction parameters, satisfactory correlation agreement is presented for each binary mixture.     

高温高压下甲烷在碳酸氢钠溶液中溶解度测定及模型计算

用新建立的一套测定高温和高压下气体溶解度的实验装置，测定了在不同温度、压力和浓度下，甲烷在碳酸氢钠溶液中的溶解度。用改进的适用于电解质体系的ＰＴ方程对甲烷在碳酸钠溶液中的溶解度进行了计算。     

An electrochemical impedance spectroscopy study of copper in a bentonite/saline groundwater environment

Pure copper samples have been exposed for 6 years in a bentonite test parcel in the Äspö Hard Rock Laboratory, which offers a realistic environment for the conditions that will prevail in a deep repository for high-level radioactive waste disposal in Sweden. After retrieval of the test parcel, a bentonite test package containing the samples was placed in a container and sealed with a thick layer of paraffin, and later on new copper and platinum samples were installed. An electrochemical impedance spectroscopy study has been performed on the pre-exposed and new copper samples for different durations in the retrieved test package.The impedance spectra for copper in the bentonite/saline groundwater environment change considerably with time of exposure. The change is more pronounced at higher than at lower frequencies. It is presumed that the corrosion resistance of pure copper in this environment mainly depends on a thin protective cuprite film that forms readily, and on a thick porous outer corrosion product layer (mainly cuprite) that develops slowly and partly intermixes with the bentonite. The impedance data revealed that both the inner and the outer corrosion product layer were involved in the impairment and the recovery of the corrosion resistance when the copper interface was disturbed during retrieval of the bentonite test package.     

Solubilities of anthracene,fluoranthene and pyrene in organic solvents: Comparison of calculated values using UNIFAC and modified UNIFAC (Dortmund) models with experimental data and values using the mobile order theory

The solubility of anthracene in 43 organic solvents, fluoranthene (45 solvents) and pyrene (30 solvents) has been calculated using UNIFAC and Modified UNIFAC (Dortmund) models to estimate the activity coefficient of the solute. It was found that both UNIFAC and Modified UNIFAC described better the solubilities in polar solvents like alcohols, ketones, esters and ethers than in nonpolar solvents like alkanes and aromatic hydrocarbons. UNIFAC and the Mobile Order Theory supplement each other well in calculating the solubilities, which means that one can choose the right model depending on the solvent one is using.     

Modelling of long-term diffusion–reaction in a bentonite barrier for radioactive waste confinement

Bentonites have been proposed as buffer material for barriers in geological disposal facilities for radioactive waste. This material is expected to fill up by swelling the void between the canisters containing the waste and the surrounding ground. However, the bentonite barriers may be submitted to changes of humidity, temperature variation, fluid interaction, mass transport, etc. This could modify the physico-chemical performance of the barrier, mainly on the interface with the steel container and with the geological barrier. The engineered barrier development necessitates thus the study of the physico-chemical stability of its mineral component as a function of time under the conditions of the repository in the long-term.The purpose of the present study was two-fold. Firstly, it was hoped to simulate the chemical transformations (geochemical and cation exchange reactions) coupled with diffusion of chemical-elements into the engineered barrier under repository conditions by applying a thermokinetic hydrochemical code (KIRMAT: Kinetic Reactions and Mass transport).Secondly, it was hoped to apply a simplified method to estimate the swelling capacity evolution by a volume balance in the fluid-saturated engineered barrier, considering that the decay of swelling capacity is directly proportional on the volume of transformed montmorillonite and, taking into account that it may be partially compensated by the volume of neo-formed swelling clays.The system modelled herein was considered to consist of 1-m thick zone of water-saturated engineered barrier. This non-equilibrated system was placed in contact with a geological fluid on one side, which was then allowed to diffuse into the barrier, while the other side was kept in contact with a source of metallic iron. Reducing initial conditions(P_O2 0; Eh = − 200 mV) and a constant reaction temperature (100 °C) were considered.The results showed that the EB in contact with the geological fluid was highly transformed after 10,000 years, whereas the most significant chemical processes were illitization, cation exchange and saponization, extending up to 20 cm into the EB. Chemical transformations of minor importance in the EB were identified as well, such as a neo-formation of silicates (quartz, cristobalite), anhydrite, laumontite, magnetite and chlorite in the system.A simplified method based on volume balance showed that the swelling capacity of the bentonite barrier is slightly affected after 10,000 years of diffusion–reaction (D close to 1) because the volume of neo-formed swelling-clays is almost directly proportional to the volume of transformed Na/Ca-montmorillonite, except for a strong illitization and/or neo-formation of non-swelling clays. In the present study, this simple approach predicted that the decay of swelling capacity of the engineered barrier is drastically affected close to the geological barrier-engineered barrier interface. Out this zone the swelling capacity decay lies between 5% and 11%.     

Correlation of solute solubility in supercritical carbon dioxide using a new empirical equation

A new empirical equation is proposed to correlate solute solubility in supercritical carbon dioxide (SCCO₂). The new empirical model has four parameters per each solute that can be obtained by correlation of the experimental solubility data. The input variables of the equation are pressure, temperature and density of pure SCCO₂. The new equation is applied for correlation of solubility of 24 compounds in SCCO₂ at wide range of temperatures and pressures. The overall percent of absolute average relative deviation (%AARD) of the new equation for correlation of the experimental data is 6.54%. Comparison of the results of the present model with a three-parameter and a four-parameter empirical model demonstrates good accuracy of the new empirical model.     

Some trends and a prediction of the solubility of gases in liquids and the heat of dissolution

An equation is derived for an approximate calculation of the solubility of gases in liquids and of their heat of dissolution using the energy parameters (force cosntants) of the Lennard-Jones potential data of pure gases and solvents, but without using empirical coefficients determined from the properties of binary systems. The equation describes some trends including the linear dependence of the gas solubility logarithm and the dissolution heat on the square root of the force constant of the Lennard-Jones potential of the gas, the extremal dependence (via the maximum) of the gas solubility on the same constant of the solvent, and the possibility and condition of the appearance of a minimum in the gas solubility with variations in temperature. The theoretical results are compared with experimental data.     

Solubility of CO2 in Aqueous Piperazine and its Modeling using the Kent‐Eisenberg Approach

A systematic investigation of the equilibrium solubility of CO₂ in aqueous piperazine solutions was conducted in a double‐jacketed stirred cell reactor. The solubilities of CO₂ in the solution were measured at 20, 30, 40, and 50 °C with CO₂ partial pressures ranging from 0.4–95 kPa. Generally the aqueous piperazine solution exhibits the same characteristics as conventional alkanolamines. Increasing the CO₂ partial pressure increases the gas loading, however increasing the temperature or concentration decreases the CO₂ loading. The values of the CO₂ loading obtained confirm that the piperazine forms stable carbamates. The equilibrium solubility data were analyzed using a Kent‐Eisenberg approach. Representation of the model is generally in good agreement with that of the experimental data, especially at high temperature.     

Removal of Pb(II) from aqueous solutions by using clinoptilolite and bentonite as adsorbents

In the present study, the ability of natural zeolite clinoptilolite and bentonite (clay) to remove Pb(II) from aqueous solutions has been investigated in batch reactors with a maximum contact time of 120 min. Adsorption tests of Pb(II) were carried out using a solution concentration of 1,036 ppm at initial pH = 4, and solid to liquid ratio of 2 g/100 mL. The effects of agitation speed (0, 100, 200, 500 rpm), temperature (28°C, 45°C, 60°C) and particle size (2.5–5.0 mm, dust) of the minerals were examined. The effect of acidity of the aqueous solution was also examined. Bentonite was found to be more effective for the removal of Pb(II) than clinoptilolite, under the experimental conditions used. The removal of Pb(II) using bentonite reached 100% at ambient temperature and mild agitation (100 rpm), while it was approximately 90% at 60°C without agitation. On the other hand, the highest removal level reached by clinoptilolite was 55%. Clinoptilolite dust is found to be more efficient than granular clinoptilolite. Agitation and temperature affected the uptake of Pb(II), especially in the case of granular clinoptilolite (2.5–5.0 mm). Finally, it can be seen that acidity of the aqueous solution influences the removal of lead by the minerals. The adsorption of lead increases with an increase in pH of the solution from 1 to 4.     

The treatment of waste-air containing mixed solvent using a biofilter 2. Treatment of waste-air containing ethanol and toluene in a biofilter

An experiment for five stages of a biofilter-run was performed to investigate the effect of hydrophilic ethanol and hydrophobic toluene on the biodegradation of hydrophobic toluene and hydrophilic ethanol, respectively, when waste-air containing toluene and ethanol was treated by a biofilter. Removal efficiencies of toluene and ethanol began to decrease when inlet load surpassed 90 g/m³/h and 100 g/m³/h consistent with maximum elimination capacities of toluene and ethanol, respectively. At the end of the biofilter-run, removal efficiencies for toluene and ethanol were decreased and maintained at 65% and 40%, respectively. The concentration of toluene at 1st sampling port was raised by factor of two in the 3rd stage of the biofilter run when the inlet load of ethanol co-feed was increased by 1.5 times, while the process conditions of toluene were maintained the same as those of the 2nd stage of biofilter-run. According to the result of Mohseni and Allen, it may be interpreted that removal efficiency of hydrophobic toluene was affected by the presence of hydrophilic ethanol when high load of hydrophobic toluene was applied like that of the 1st sampling port of the biofilter. However it was not the case when a low load of hydrophobic toluene was applied like those of the 2nd, 3rd and 4th sampling ports since hydrophobicity of toluene is much less that of α-pinene. Thus, it may be suggested that biodegradation of hydrophobic VOC was interfered by hydrophilic VOC dissolved in the biolayer and the degree of interference was proportional to the inlet load of hydrophobic VOC as well as that of hydrophilic VOC and was inversely proportional to the solubility of hydrophobic VOC. However, it was inferred that the existence of hydrophobic toluene from waste-air can hardly inversely hinder the removal of hydrophilic ethanol in the biofilter when timeevolutions of hydrophilic ethanol concentrations of this experiment were compared with those of the previous experiment of biofilter to treat waste-air containing ethanol only.     

Solubility analysis of clozapine and lamotrigine in supercritical carbon dioxide using static system

The experimental techniques used to obtain the solubilities of clozapine and lamotrigine in supercritical carbon dioxide include a simple static technique. The solubility measurements were performed at temperatures between 318 and 348 K and pressures between 121.6 and 354.0 bar. These chemicals have solubilities with values ranging from 3.6 × 10⁻⁶ to 4.2 × 10⁻⁵ (clozapine) and 1 × 10⁻⁶ to 6 × 10⁻⁵ (lamotrigine) mole fraction. The solubility data were correlated using four semi-empirical density-based models (Chrastil, Bartle, K-J and M-T models). Correlation of the results shows good self-consistency of the data obtained with the Bartle model for clozapine with an overall average absolute relative deviation (AARD%) of 11.21. The calculated results with each four models show satisfactory agreement with the experimental data for lamotrigine with an overall AARD% 11.72, 8.99, 2.75, 3.86 for Chrastil, K-J, Bartle, M-T models, respectively. Using the correlation results, the heat of drug-CO₂ solvation and that of drug vaporization were approximated.     

The process dynamics of filler retention in paper using a CPAM/bentonite retention aid system

In an effort to develop robust control strategies for the wet‐end of papermaking, an experimental program was carried out to model the dynamic behaviour of the filler retention in paper using a Fourdrinier pilot paper machine and a cationic poly(acrylamide)/bentonite retention aid system. A dynamic simulation model of the pilot paper machine was developed from first‐principles. To describe the wet‐end chemistry effect, the first‐pass retention was included in the model as a new independent variable. The important factors affecting the dynamics of the wet‐end are first‐pass retention and the parameters related to the white water circulation.     

褐煤气化半焦对地下水有机污染的模拟脱除

通过自制的煤炭地下气化模拟系统,采用富氧空气/水蒸气两阶段气化工艺,完成内蒙褐煤的地下气化模拟实验。利用傅里叶红外光谱、低温氮气物理吸附仪和扫描电镜对气化残留半焦的表面官能团、孔结构及表面形貌进行表征,进而考察了半焦对苯酚模拟废水中苯酚及煤气洗涤水中总有机碳（TOC）的脱除效果。实验结果表明：半焦孔径主要分布在1~4nm之间,表面有较丰富的含氧官能团及较多的孔洞和裂隙,其孔结构、含氧官能团及孔洞裂隙均有利于污染物在半焦内的迁移和吸附;气化半焦对苯酚的吸附符合Langmuir等温吸附模型,为单分子层吸附;实验条件下最大吸附率为97.95%,吸附量为2.44mg/g;气化半焦对煤气洗涤水中TOC的脱除随吸附时间的变化具有阶段性,脱除率可达88.1%。     

催化波极谱法测定化探样品中钨量及钼量

试样经碱熔分解,水提取,铁、锰、钴、镍元素呈氢氧化物沉淀与钨、钼分离。在0.34 moL/L硫酸-2 g/L苯羟乙酸-24 g/L氯酸钠-0.08g/L辛克宁体系中,钨和钼均能产生灵敏的极谱催化波,峰电位约为-0.70 V和-0.07 V(对饱和甘汞电极)。方法检出限为W 0.29μg/g、Mo 0.26μg/g,精密度(RSD,n=12)为W 1.21%~10.1%、Mo 2.7%~12.4%,准确度(RE,n=12)为W-3.7%~2.33%、Mo-4.79%~3.17%。适用于化探样品中钨钼元素的连续测定。     

Estimation of H2S solubility in ionic liquids using a rigorous method

Prediction of acid gases solubilities in ionic liquids (ILs), have recently emerged as promising mediums for refining of natural gas, using powerful paradigms is of great importance from technical and economical point of view. In this respect, this study aims at appraising the effectiveness of one of the new generation soft computing methodologies called gene-expression programming (GEP) for estimating the hydrogen sulfide (H₂S) solubility in ionic liquids (ILs). A total data set of 465 experimental data belonging to 11 ionic liquids, which gathered from literatures, were used to develop a general correlation. The temperature and pressure accompanied with acentric factors and critical temperature and pressure of ILs were used as independent input variables, while H₂S solubility as dependent output variables. The modeling results showed the coefficient of determination (R²) of 0.9902 and 0.0438% mean absolute relative error (MARE) for the predicted solubilities from the corresponding experimental values. Therefore, the model is comprehensive and accurate enough to be used to predict the H₂S solubility in various ILs. In addition, the GEP-model predictions were compared with the outputs of two well-known engineering approaches named Soave–Redlich–Kwong (SRK) and Peng–Robinson (PR). Results showed that the proposed evolutionary-based method was more accurate than the widely used aforementioned thermodynamic models.     

Synthesis of vaterite CaCO3 as submicron and nanosized particles using inorganic precursors and sucrose in aqueous medium

It is reported the synthesis of CaCO₃ vaterite as stable nanoparticles and submicron-sized by a simple and relatively rapid procedure. XRD, SEM and FTIR techniques have been used to characterize the precipitated products. The synthesis is based on chemical precipitation of inorganic salt precursors, calcium nitrate tetrahydrate and sodium bicarbonate, and using the disaccharide sucrose as an additive in aqueous medium. The role of the disaccharide sucrose is to control the vaterite precipitation after nucleation and growth. It has been found that an increase in sugar concentration promotes the crystal precipitation of vaterite with spherulitic morphology, as revealed by SEM, and changed the surface of the precipitated particles. There is a significant difference between CaCO₃ precipitation in the absence and presence of sucrose. Addition of 0% of sucrose leads to 83% of calcite as identified by XRD methods. In contrast, addition of 67% of sucrose in aqueous medium produces 100% vaterite. The present results may be useful to provide a quick, simple, inexpensive and novel method for the controlled synthesis of new advanced biomaterials based on vaterite particles without hazardous chemicals and inert atmosphere, with great possibilities for industrial scale production.     

Drying of Liquid and Pasty Products in a Modified Spouted Bed of Inert Particles

A novel type of a dryer is presented in which finely dispersed liquids or pastes are dried in a modified spouted bed of inert particles. Due to unique configuration of a drying chamber and gas distributors, the dryer combines advantages of the spouted bed, swirling bed, and counter-rotating impinging streams. Correlations and graphs for design calculations are given.     

Simultaneous measurement of the concentration of a supercritical gas absorbed in a polymer and of the concomitant change in volume of the polymer. The coupled VW-pVT technique revisited

The purpose of this article is to re-examine the simultaneous measurements of the concentration of a supercritical gas in a polymer and of the concomitant change in volume of the polymer with the coupled VW-pVT technique [Hilic S, Pádua AAH, Grolier J-PE. Rev Sci Instrum 71 (11) (2000) 4236-41; Hilic S, Boyer SAE, Pádua AAH, Grolier J-PE. J Polym Sci B: Polym Phys 39 (2001) 2063-2070]. The experimental set-up consists of an original coupling of two techniques, a vibrating-wire sensor VW to weigh the polymer sample during the sorption and a pressure decay pVT-method to measure the quantity of gas, transferred from a high-pressure calibrated volume, which is absorbed by the polymer sample. The present study is related to the sorption and desorption of light gases (like CH₄, CO₂, H₂S, N₂) usually found in petroleum products circulating in pipelines made of semicrystalline polymers (like polyolefins and fluorinated polymers).Results for CO₂ in medium-density polyethylene, MDPE, and in poly(vinylidene fluoride), PVDF (or PVF₂), in the range of temperatures up to 391 K and pressures up to 43 MPa, are reported and discussed. Experiments allow the apparent concentration of gas dissolved in the polymer to be established; the associated swelling of the polymer is estimated using the Sanchez-Lacombe equation of state. Then, the data of the corrected concentration of the gas in the polymer are correlated with the semi-empirical ‘dual-mode’ model. Whenever possible to compare our results are in good agreement with existing literature data.