Sharif Digital Repository

Synergistic coupled transport of uranyl ion across a bulk liquid membrane of chloroform has been investigated using a dioxa-diazamacrocycle and oleic acid as carrier and synergistic agents, respectively. Quantitative transport of uranyl ion was achieved within 4 h when the pH of source solution was kept at 5.0–6.0 and mole ratio of carrier to synergistic agent was 1/15. It was found that overall rate and selectivity of the transport is governed by the stripping step. Finally, the influence of some foreign competitor ions including Al3+, Ca2+, CO3 2−, Cu2+, Mg2+, Pb2+, Zn2+ and Th4+ and also the ionic strength on the transport efficiency has been evaluated. © 2018, Akadémiai Kiadó, Budapest,... 

A standard simulating technique test was investigated to assess the atmospheric corrosion behavior of silver coating. The rates of formation of corrosion products were measured in the simulating atmospheres of 100% humidity containing SO 2,H 2S and a complex atmosphere consist of SO 2,H 2S and NO 2 gases ,based on the mass increase method. The concentrations of corrosive gases were chosen according to real world conditions. XRD, SEM and EDS were used to examine the morphology and to determine the composition of the corrosion products under different experimental conditions. Results revealed the formation of Ag 2SO 4 and Ag 2S on the silver coating surfaces in the SO 2 and H 2S containing... 

Metal pH50 and ΔpH50 values were determined and compared for a number of organic systems to select a synergistic system for the separation of Cd from Zn. The largest ΔpH50(Zn-Cd) value was obtained with HRJ-4277 (nonylsalicylic acid)/Cyanex 471X (triisobutyl phosphine sulphide or TIBPS) system and reached 1.53 pH units, indicating excellent separation of Cd from Zn with this system. Shellsol 2046 was chosen as the diluent of the system due to its larger ΔpH50(Zn-Cd) and excellent phase separation compared with other diluents. Distribution isotherms and subsequent McCabe-Thiele diagrams indicate that 99% Cd could be extracted in two stages at pH 3.80 and A / O ratio of 1.5 : 1. The extraction... 

In this study, solvent extraction method has been utilized for separation of molybdenum and vanadium from nitrate solution by utilizing coupling of acid and solvating extractants (D2EHPA and TBP extractants). The outcomes demonstrated that synergistic solvent extraction improves stability of formatted complexes for transfer to the organic phase. The main parameters such as pH value, concentration of extractants, NH4OH concentration as the stripping agent and contact time were optimized at 0.4, 15% (v/v) D2EHPA, 10% (v/v) TBP, 2 M and 30 min, respectively. The maximum separation factor of 24.84 was obtained with a new synergistic mixture of D2EHPA and TBP diluted with kerosene. According to... 

Formation of machinable glass-ceramic in the system MgO-SiO 2-Al2O3-K2O-B2O 3-F with and without addition of MgF2 has been investigated. Crystallization of glass sample was done by controlled thermal heat treatment at nucleation and crystallization temperatures. The results showed that MgF2 in high concentration had a synergistic effect and enhanced the formation of interlockedmica crystals. Non-isothermal DTA experiments showed that the crystallization activation energies of base glasses were changed in the range of 235-405 kJ/mol, while the crystallization activation energies of samples with addition of MgF2 were changed in the range of 548-752 kJ/mol  

In the present study, the thermodynamics and mechanisms of vanadium extraction by a mixture of bis-2-ethylhexyl phosphoric acid (D2EHPA) and tri-n butyl phosphate (TBP) from sulfate medium were investigated. It was found that the maximum extraction percent of vanadium occurs at pH 1.8 under ambient conditions; this phenomenon was ascribed to the predominant presence of cationic species of vanadium (VO2+) at this pH. Based on the Fourier Transform Infrared (FT-IR) spectrums, the POH bond of D2EHPA was found responsible for the extraction of VO2+ species through a cationic exchange mechanism. Employing the slope analysis method showed that the stoichiometric reaction... 

Direct extraction of molybdenum from sulfate solution with synergistic extractants (mixture of D2EHPA and TBP) was studied in the rotation column. The influence of extractant concentration and initial pH of aqueous phase was studied in the bench scale experiments. The outcomes demonstrated that the synergistic solvent extraction enhances the constancy of the extracted complexes for transfer into the organic phase. In the continuous experiments, the effect of different operating parameters such as speed of agitation, inlet solvent flow rate and inlet aqueous flow rate on the holdup, mean drop size, drop size distribution, slip and characteristic velocities and extraction percentage were... 

Synergistic effects of Cyanex 272 mixed with D2EHPA and Cyanex 302 mixed with D2EHPA were investigated for the separation of cobalt and nickel from a dilute sulfate media with the aim of reducing the reagent cost. Selective extraction of cobalt over nickel improved with respect to D2EHPA, but worsened with respect to Cyanex 272. By the application of the slope analysis method, the stoichiometric coefficient of the extractant was found to be four for cobalt and five for nickel, in a mixture of D2EHPA with Cyanex 302. However, it was four for both cobalt and nickel in a mixture of D2EHPA with Cyanex 272. Fourier Transform Infrared Spectroscopy (FT-IR) was utilized to examine the... 

The corrosion inhibition effect of zinc acetylacetonate (ZAA) and benzothiazole (BTH) mixture was evaluated for mild steel in 3.5% NaCl solution. To this end, ZAA:BTH mixtures ranged from 6:1 to 1:6 mol ratios were examined by weight loss and open circuit potential to obtain optimal mole ratio. The optimal mixture of ZAA:BTH at 1:5 mol ratio showed a significant corrosion inhibition efficiency proved by electrochemical impedance spectroscopy and polarization studies. The addition of the optimal mixture of ZAA:BTH to epoxy coating showed a considerable increase of corrosion protection evaluated by salt spray exposure  

In this work, a newly formulated sulfonate-based surfactant and two other commercial sulfate-based surfactants with the capability of tolerating harsh underground reservoir conditions, such as high-saline formation water and high temperature, were prepared. Sodium metaborate as an effective alkali compound was also used to provide alkali-surfactant combination. Interfacial tension (IFT) measurements as well as wettability examinations for different salinities and mixture conditions were performed for an extended range of the chemical concentrations. The wettability tests including both contact angle measurements and Amott cell tests were performed on saturated Berea sandstone plug samples... 

PVDF/nanoclay nanocomposites were prepared via melt mixing method. The intercalated dispersion of the nanoclay in PVDF matrix was confirmed by XRD. According to FTIR, DSC and XRD results, the presence of nanoclay facilitated transition from α-to-β crystalline phase. Electron beam irradiation decreased the melting point of the nanocomposites. The decrease in melting point of the nanocomposites was about 11 C at 500 kGy. The crystallinity of nanocomposites increased at an irradiation dose of 100 kGy and decreased at higher irradiation doses. The extent of crosslinking of the nanocomposites increased significantly with irradiation up to 300 kGy. The nanoclay intensified the increase in yield... 

Different concentrations of CaF2 were incorporated in mica glass-ceramics to evaluate their effects on the crystallization and microstructure. The kinetics of phase transformations, and the microstructures of the final crystalline phase were found to be dependent on the concentration of nucleation agents. The results showed that CaF2 in high concentration had a synergistic effect and enhanced the formation of interlocked mica crystals. Non-isothermal DTA experiments showed that the crystallization activation energies of base glasses were changed in the range of 235-405 kJ/mol, while the crystallization activation energies of samples with addition of CaF2 were changed in the range of 419-747... 

In this work, a newly formulated sulfonate-based surfactant and two other commercial sulfate-based surfactants with the capability of tolerating harsh underground reservoir conditions, such as high-saline formation water and high temperature, were prepared. Sodium metaborate as an effective alkali compound was also used to provide alkali-surfactant combination. Interfacial tension (IFT) measurements as well as wettability examinations for different salinities and mixture conditions were performed for an extended range of the chemical concentrations. The wettability tests including both contact angle measurements and Amott cell tests were performed on saturated Berea sandstone plug samples... 

The present work reports the synthesis of a Pt-modified NiO–Al2O3 nanocomposite derived from graphene-supported layered double hydroxide (Pt–NiO/G) and demonstrates its catalytic activity. The resulting Pt–NiO/G nanocomposite was characterized by FT-IR, XRD, FE-SEM, TEM and XPS techniques and used for catalytic reduction of p-nitrophenol (P-NP) to p-aminophenol (P-AP). The influence of graphene on catalytic activity was comparatively considered by preparation of Pt–NiO nanoparticles derived from layered double hydroxide. The superior catalytic performance of Pt–NiO/G was ascribed to the synergistic effect between Pt and NiO. Furthermore, reduction of P-NP was considered to follow a...