Effect Of Dissolution Temperature Research Articles

Comprehensive analysis of lignin dimer dissolution microscopic mechanism in different aromatic-based deep eutectic solvent

Aromatic-based deep eutectic solvent (DES) is a novel kind of DES that can dissolve lignin efficiently. Density functional (DFT) calculation, molecular dynamics (MD) simulation and multivariate analysis were used to investigate the interaction mechanism of five aromatic-based DES on two lignin dimer models. The effects of dissolution temperature and the type of aromatic hydrogen bond donor (HBD) on the breaking bonds between β-O-4 and 5–5 substructural units or interacting with different functional groups on lignin were investigated. With the introduction of DES, the electrostatic interaction between Cl- and lignin was obvious, while the van der Waals interaction between HBD, Ch+ and lignin was obvious. Among all the aromatic-based DES, choline chloride/p-hydroxybenzoic acid (ChCl/PB) is considered to have efficient dissolution effect. In the process of lignin dissolution, γ-OH was the preferred site for PB and Cl- acting on the lignin dimer (β-O-4), and the proportion of hydrogen bonding with γ-OH is 40 %. It was distributed around the lignin dimer (β-O-4) at 0.28–0.32 nm, and the total interaction energy was −4041.1452 kJ/mol. This study provided novel insights and theoretical basis for the preparation of renewable DES using aromatic components.

Effect of Dissolution Temperature on Purity of LaNi5 Powder Synthesized with the Combustion-Reduction Method

The LaNi5 intermetallic phase has been extensively investigated because of its excellent properties, such as attractive hydrogen storage, medium plateau pressure, and easy activation. LaNi5 phase is generally produced by a complicated method, which involves several steps, i.e. melting, alloying, casting, softening and making them into powder. This study aimed to develop a new LaNi5 synthesis process by modifying the combustion-reduction method. In this method it is very important to produce La2NiO4, because LaNi5 is formed from the process of reducing this phase. The precursor powders La(NO3)3.6H2O and Ni(NO3)2.6H2O were reacted with distilled water as a solvent medium and mixed using magnetic stirring. The synthesis process was carried out at room temperature, 60 °C, 70 °C, and 80 °C for 10 minutes until the solution became transparent green. The solution was then dried for 2 hours at 100 °C to form a transparent green gel. The gel was calcined at a temperature of 500 °C for 2 hours, producing a black powder. The optimal black powder was then reduced using CO gas at 600 °C for 2 hours. The powder samples were characterized using XRD, FTIR, and SEM-EDX. The analysis revealed that synthesis at room temperature was the most optimal method for the reduction process because it produced the most La2NiO4, at 12.135 wt%.

Separation and Recovery of Platinum and Palladium from Spent Petrochemical Catalysts Using Activated Carbon, Analysis of Two Kind of Most Used Catalysts in Petro Chemistry

The goal of this work is the separation and recovery of platinum and palladium from spent catalyst. The recovery consisted of separating the maximum amount of platinum and palladium from catalysts and changing them into usable forms. The petroleum and petrochemical units use Pt and Pd catalyst for reactions such as reforming and hydrogenation. Because these materials contain valuable metals, such as Pt and Pd, these metals should be recycled. Based on economic reasons and the high price of new catalysts, petrochemical companies should solve this problem. The new method in this work may help to recover these metals from spent catalyst. This method may help solve several environmental problems. In this work, the recovery of platinum and palladium from petroleum catalysts has been studied using spent catalysts. Two catalysts were characterized by XRF, XRD, and AAS. Aqua regia, used as a leaching agent, and the effect of dissolution temperature and time, Liquid/Solid (L/S) ratio, size of particles, and elimination of coke were also investigated. Under optimized conditions, the leaching process was done with 98% efficiency. Recovery of platinum and palladium from the leached solutions was done by the adsorption process with Activated Carbon (AC) in an environmentally friendly manner. According to the results, the optimum operating conditions for platinum and palladium removal by activated carbon were a temperature of a solution of 85 and 98℃, pH = 0.5 and 2, time of adsorption 180 and 150 min and adsorbent loading capacity = 18.75 mgPt/gAC and 12.5 mgPd/gAC, respectively. The activated carbon containing platinum and palladium was decomposed by ignition to produce platinum and palladium powder with commercial purity of 96.5% and 96.3% respectively.

Dissolution of Expanded Polystyrene in Cycloalkane Solutions

Feasibility of dissolution and utilization of expanded polystyrene in cycloalkane solutions was investigated in this work. The dissolution process of expanded polystyrene in several cycloalkane solutions decalin, cyclohexane and methyl cyclohexane was studied. The effect of dissolution temperature, mechanical agitation, ultrasonic wave and stirring rate was studied under optimized conditions. Mass transfer coefficients were fitted. The results showed that the dissolution rate of expanded polystyrene in different cycloalkane solutions was ranked as decalin > methyl cyclohexane > cyclohexane; higher dissolution temperature and faster stirring rate could speed up the dissolution of expanded polystyrene; the effect of mechanical agitation was superior to ultrasonic condition; the solubility of top face was better than side face and under face.

Extraction of the RO Phase from Steel Slag

Through the XRD and XRF analysis of the converter steel slag, we can identify the chemical components and the mineral phase and ensure the extraction method of RO phase from steel slag. The possibility of the extraction of silicate phase from steel slag with Salicylic acid ethanol (SAE) solution was studied firstly. Then, the effect of dissolution temperature of steel slag, dissolution time of the samples, concentration of salicylic acid and specific surface area of steel slag on the extraction mass of silicate phase were analyzed by orthogonal experiment, and the optimum experiment conditions of the extraction of silicate phase from steel slag with SAE solution were concluded. Finally, the RO phase was obtained by the extraction and separation of the intermediate phase from steel slag using potassium hydroxide-sucrose (KOSH) solution. The effect of extraction was determined by detecting the chemical and mineral composition of the extracted residue with XRD and XRF. The results show that the SAE solution can be used to extract the silicate phase from steel slag and the best extraction conditions were 40 degrees of dissolution temperature, 3 h of solution time, salicylic acid concentration 0.2 g/ml and the specific surface area of steel slag 600 m2/kg. Then the intermediate phases (mainly C2F) from steel slag were extracted by KOSH solution, which can get a relatively pure RO phase. The experiment provides a basis for further exploring the cause of the difference in activity of RO phase and improving the utilization ratio of steel slag.

Cellulose dissolution and regeneration using various imidazolium based protic ionic liquids

A new series of six protic ionic liquids (PILs) comprising substituted imidazolium cations paired with lactate or glycolate anions were synthesized for cellulose dissolution. All the six synthesized PILs were able to dissolve about 5wt% of cellulose. Especially, 1-ethyl imidazolium lactate showed highest dissolution power since 5wt% of cellulose solution was obtained within 20min at 80°C. The effects of dissolution temperature on cellulose dissolution time were also investigated. As the dissolution temperature increases, dissolution time reduces significantly. The regeneration of cellulose with higher yield was achieved by adding anti-solvent like deionized water to the cellulose solution. Both the initial and regenerated cellulose samples were characterized by X-ray diffraction (XRD), thermogravimetric analysis (TGA) and scanning electron microscope (SEM) analysis. The results showed that the crystalline structure of initial cellulose (cellulose I) gets converted to cellulose II. In addition, all regenerated cellulose possessed nanostructure and lower thermal decomposition temperature than the initial cellulose and had new vistas in the industrial applications.

Dissolution of cellulose with ionic liquid in pressurized cell

In recent years, ionic liquids (ILs) have emerged as a potentially attractive “green” solvent for the dissolution of cellulose for further chemical processing. Generally, the dissolution of cellulose in ILs via a conventional heating system requires high temperature and long pretreatment time. This article investigates the effect of pressure on the dissolution of cellulose in IL [emim][OAc] (1-ethyl-3-methylimidazolium acetate). The effects of dissolution temperature and dissolution pressure on cellulose dissolution time were investigated using High Pressure Solubility Measurement System (HPSMS).

Dissolution of cellulose in phosphate-based ionic liquids

Two kinds of alkylimidazolium salts containing dimethyl phosphate or diethyl phosphate were obtained as room temperature ionic liquids synthesized by one step, and both of them have the ability to dissolve untreated cellulose. Especially, 1-ethyl-3-methylimidazolium diethylphosphonate ([EMIM]DEP) could obtain 4 wt% cellulose solution within 10 min under 90. The effects of dissolution temperature on cellulose dissolution time and degree of polymerization were investigated. As dissolution temperature increased, dissolution time was greatly reduced. Both the original and regenerated cellulose samples were characterized with wide-angle X-ray diffraction, thermogravimetric analysis and scanning electron micrograph. The results showed that the crystalline structure of cellulose was converted to cellulose II from cellulose I in native cellulose. It was also found that the regenerated cellulose had good thermal stability with [EMIM]DEP ionic liquid.

On quantifying the dissolution behaviour of milk protein concentrate

Milk protein concentrate (MPC) is a newly developed dairy powder with wide range of applications as ingredients in the food industry, such as cheese, yogurt, and beverage. MPC has relatively poor solubility as a result of their high protein content (40–90 wt%), with distinct dissolution behaviour in comparison to skim milk or whole milk powders. Here, a focused beam reflectance measurement (FBRM) was used to monitor the dissolution process of an MPC powder, with the data used to develop a kinetic dissolution model based on the Noyes–Whitney equation. The model was used to estimate the dissolution rate constant k and the final particle size in suspension d ∞, describing dynamic dissolution behaviours and final solubility respectively of a particular powder. In this work, the effects of dissolution temperature, storage duration and storage temperature on dissolution properties of an MPC powder were also investigated. A quantitative understanding of relationship between process and storage conditions with powder functionality could be achieved from k and d ∞ profiles. This approach can potentially be applied to predict the dissolution behaviour of specific dairy powders in a more robust manner than conventional solubility tests.

Recovery of Platinum and Palladium from the Spent Petroleum Catalysts by Substrate Dissolution in Sulfuric Acid

In this study, the recovery of platinum and palladium from petroleum catalysts has been elaborated using a method consisting mainly of dissolving alumina substrate in sulfuric acid thereby concentrating the precious metals in the residue. The effect of dissolution temperature and time, concentration of sulfuric acid, and pulp density on the dissolution of alumina substrate was investigated systematically. The optimum dissolution conditions for the platinum catalysts AR-405 and R-134 were: sulfuric acid 6.0mol/L, dissolution temperature 100°C, dissolution time 2~4 h, pulp density 220 g/L. The dissolution of R-134 catalyst the substrate consisting only of γ-Al 2 O 3 phase was higher than that of AR-405 which contained the mixture of γ-Al 2 O 3 or α-Al 2 O 3 . The optimum conditions for LD-265 are: sulfuric acid concentration 8.0mol/L, dissolution temperature 100°C, pulp density 220 g/L and time 18 h. It was found that platinum and palladium which was impregnated to alumina substrate as fine particles, also dissolved to some extent during sulfuric acid treatment. They could be recovered by a cementation process using aluminum powder. The complete recovery of Pt from AR-405 and R-134 catalysts was possible by the proposed method. Nevertheless, the method may not be applicable to LD-265 catalyst due to the time-consuming substrate dissolution process.

A study of the bio-accessibility of welding fumes

The respiratory bio-accessibility of a substance is the fraction that is soluble in the respiratory environment and is available for absorption. In the case of respiratory exposure the amount of absorbed substance plays a main role in the biological effects. Extensive bio-accessibility studies have always been an essential requirement for a better understanding of the biological effects of different workplace aerosols, such as welding fumes. Fumes generated using three different welding techniques, manual metal arc (MMA) welding, metal inert gas (MIG) welding, and tungsten inert gas (TIG) welding were investigated in the present study. Each technique was used for stainless steel welding. Welding fumes were collected on PVC membrane filters in batches of 114 using a multiport air sampler. Three different fluids were applied for the solubility study: deionised water and two kinds of lung fluid simulants: lung epithelial lining fluid simulant (Gamble's solution) and artificial lung lining fluid simulant (Hatch's solution). In order to obtain sufficient data to study the tendencies in solubility change with time, seven different leaching periods were used (0.5, 1, 2, 4, 8, 16, 24 h), each of them with three replicates. The effect of dissolution temperature was also studied. The total amounts of selected metals in the three different welding fumes were determined after microwave-assisted digestion with the mixture of aqua regia and hydrofluoric acid. The most obvious observation yielded by the results is that the solubility of individual metals varies greatly depending on the welding technique, the composition of the leaching fluid and leaching time. This study shows that the most reasonable choice as a media for the bio-assessment of solubility might be Hatch's solution by a dissolution time of 24 h.

Effect of dissolution temperature on the structures of sodium hyaluronate by flow field-flow fractionation/multiangle light scattering

Molecular weight distribution (MWD) and structural deformation of ultrahigh molecular weight (MW) sodium hylaluronate (10 5–10 8 g/mol) were studied under different sample dissolution temperature conditions, using on-line flow field-flow fractionation (FlFFF) and multiangle light scattering (MALS). Sodium hyaluronate (NaHA) materials from sarcoma fluid have been studied by dissolving them in water at three different temperature conditions (5 °C, 50 °C, and 90 °C). Frit inlet asymmetrical flow field-flow fractionation (FI-AFlFFF), with field programming, was utilized for the separation of NaHA by MW, and on-line observation of light scattering of fractionated NaHA by MALS was performed in order to determine the MWD and molecular conformation. In these experiments, NaHA molecules exhibited an extended structure from a formerly rather compact geometry when the dissolving temperature was raised to 90 °C. This study also showed a clear difference in the MWD of NaHA when a preliminary filtration process was applied.

Dilute Solution Properties of Low-temperature Polymerized Polyvinyl Chloride. I. Effects of Dissolution Temperature and Time

Dilute Solution Properties of Low-temperature Polymerized Polyvinyl Chloride. I. Effects of Dissolution Temperature and Time