Effects of antimony(III) on zinc electrodeposition from acidic sulfate electrolyte containing [BMIM]HSO<Subscript>4</Subscript>

The effect of antimony(III) on the cathodic current efficiency (CE), power consumption (PC), deposit morphology, and polarization behavior during electrodeposition of zinc from acidic sulfate solutions containing 1-butyl-3-methylimidazolium hydrogen sulfate-[BMIM]HSO₄ was investigated. The results indicated that the addition of Sb(III) alone decreased the CE, increased the PC, and deteriorated the quality of the zinc electrodeposits. However, the combined addition of Sb(III) and [BMIM]HSO₄ was found to be beneficial for zinc deposition and improved the surface morphology of the zinc electrodeposits. Maximum CE and minimum PC were obtained at the combined addition of 0.02 mg dm⁻³ Sb(III) and 5 mg dm⁻³ [BMIM]HSO₄. Depolarization of the cathode was noted in the presence of Sb(III) alone in the electrolyte whereas this effect was partly counteracted by the addition of [BMIM]HSO₄. Cathodic polarization curves were traced and analyzed to determine the electrokinetic parameters such as Tafel slope, transfer coefficient, and exchange current density so as to elucidate the nature of the electrode reactions. The data obtained from X-ray diffractogram revealed that the presence of Sb(III) did not change the structure of the electrodeposited zinc but affected the crystallographic orientation of the crystal planes.     

Effects of 1-butyl-3-methylimidazolium hydrogen sulfate-[BMIM]HSO<Subscript>4</Subscript> on zinc electrodeposition from acidic sulfate electrolyte

A comparative study of the effect of 1-butyl-3-methylimidazolium hydrogen sulfate-[BMIM]HSO₄ and gelatine on current efficiency (CE), power consumption (PC), deposit morphology, and polarization behaviour of the cathode during electrodeposition of zinc from acidic sulphate solutions were investigated. Compared with the traditional industrial additive, gelatine, the addition of [BMIM]HSO₄ was found to increase current efficiency, reduce power consumption, and improve the surface morphology. Maximum CE and minimum PC were obtained at the addition dosage of 5 mg dm⁻³. Meanwhile, simultaneous addition of the two additives induced a blocking effect of the zinc reduction and led to more leveled and fine-grained cathodic deposits. Moreover, cyclic voltammetry results and kinetic parameters such as Tafel slope, transfer coefficient, and exchange current density obtained from Tafel plots led to the conclusion that both additives have a pronounced inhibiting effect on Zn²⁺ electroreduction. The data obtained from X-ray diffractogram revealed that the presence of additives did not change the structure of the electrodeposited zinc but affected the crystallographic orientation of the crystal planes.     

Effects of temperature and current density on zinc electrodeposition from acidic sulfate electrolyte with [BMIM]HSO<Subscript>4</Subscript> as additive

The effects of temperature and current density on cathodic current efficiency, specific energy consumption, and zinc deposit morphology during zinc electrodeposition from sulfate electrolyte in the presence of 1-butyl-3-methylimidazolium hydrogen sulfate ([BMIM]HSO₄) as additive were investigated. The highest current efficiency (93.7%) and lowest specific energy consumption (2,486 kWh t⁻¹) were achieved at 400 A m⁻² and 313 K with addition of 5 mg dm⁻³ [BMIM]HSO₄. In addition, the temperature dependence of some kinetic parameters for the zinc electrodeposition reaction was experimentally determined. Potentiodynamic polarization sweeps were carried out to obtain the expression for each parameter as a function of temperature. In the condition studied, the exchange current density depended on temperature as ln(i ₀) = −a/T + b and the charge transfer coefficient was constant. Moreover, the adsorption of the additive on cathodic surface obeyed the Langmuir adsorption isotherm. The associated thermodynamic parameters indicated the adsorption to be chemical.     

Effect of ionic liquid additive [BMIM]HSO<Subscript>4</Subscript> on zinc electrodeposition from impurity-containing sulfate electrolyte. Part I: current efficiency,surface morphology,and crystal orientations

The effects of ionic liquid additive 1-butyl-3-methylimidazolium hydrogen sulfate-[BMIM]HSO₄ on the current efficiency (CE), surface morphology, and crystallographic orientations during zinc electrodeposition from acidic sulfate solutions containing some common impurities such as copper, iron, cobalt, nickel, and lead were investigated. The results indicated that all the metallic impurities studied exerted a deleterious effect on the zinc electrodeposition process by decreasing the CE, influencing the purity, and inducing changes in morphology of the cathodic deposits. The addition of [BMIM]HSO₄ was observed to relieve the harmful effects of these impurities to some extent, and led to reduce the impurity content in the zinc deposits and improve the CE and the quality of the cathodic deposits. The data obtained from X-ray diffraction revealed that the presence of these impurities alone and in combination with [BMIM]HSO₄ did not change the structure of the electrodeposited zinc but affected the crystallographic orientation of the crystal planes.     

Nucleation and growth of zinc on aluminum from acidic sulfate solution with [BMIM]HSO<Subscript>4</Subscript> as additive

The nucleation and first stages of the growth of zinc on aluminum from acidic sulfate solution in the absence and presence of 1-butyl-3-methylimidazolium hydrogen sulfate-[BMIM]HSO₄ as additive were investigated using cyclic voltammetry, chronoamperometric current–time transients, and scanning electron microscopy techniques. The dimensionless chronoamperometric current–time transients for the zinc electrodeposition on aluminum electrode from the solution free of [BMIM]HSO₄ showed the zinc deposition can be interpreted by a model involving instantaneous nucleation with hemispherical diffusion controlled growth of nuclei. The addition of [BMIM]HSO₄ induced a blocking effect on the zinc electrocrystallization process through its cathodic adsorption on the electrode surface. This effect led to increase the number density of active sites, decrease the nucleation and growth rate of these nuclei, and produce more leveled and fine-grained cathodic deposits without affecting the instantaneous nucleation mechanism. Surface morphology analysis revealed the crystal structure of the zinc deposits formed did not change by the adsorption of [BMIM]HSO₄ at the first stages of deposition.     

Optimization of [Bmim][HSO4]-Catalyzed Transesterification of Camelina Oil

1-Butyl-3-methylimidazolium hydrogen sulfate ([Bmim][HSO₄]) is utilized to catalyze transesterification of camelina oil with methanol. The major compositions of camelina biodiesel are saturated fatty acid esters (C16:0, C18:0), monounsaturated, and polyunsaturated fatty acid esters (C18:2, C18:3). The effects of reaction temperature, reaction time, M_methanol:M_{Camelina oil}, and M_[Bmim][HSO4]:M_{Camelina oil} on biodiesel production are investigated in detail, and a general mathematical model is developed to well predict the biodiesel yield. Also, [Bmim][HSO₄] is thermally stable to recycle for four times with a high biodiesel yield. The fuel properties of camelina biodiesel are all comparable to the American Society for Testing Materials (ASTM) standards.     

Recovery of magnetic ionic liquid [bmim]FeCl<Subscript>4</Subscript> using electromagnet

Recovery of 1-butyl-3-methylimidazolium tetrachloroferrate ([bmim]FeCl₄) from its mixture with water was investigated. The [bmim]FeCl₄ rich phase in the mixture forming two-phase was successfully separated, while homogeneous mixtures could not be separated. However, the concentration of the homogeneous mixture varied as a function of the magnetic field strength. Therefore, a combination of magnetic field and conventional methods to recover magnetic ILs from reaction mixtures will be very useful and have great potential.     

Electropolymerization of benzotriazole in room temperature ionic liquid [bmim]PF<Subscript>6</Subscript>

The electropolymerization of benzotriazole on an Au electrode was investigated via cyclic voltammetry and chronoamperometry in a room temperature ionic liquid medium, 1-butyl-3-methylimidazolium hexafluorophosphate ([bmim]PF₆) containing glacial acetic acid. The chronoamperometric investigation revealed that the instantaneous nucleation predominated the potentiostatic electropolymerization of benzotriazole at the oxidation peak potential. Scanning electron microscopy indicated that the polymer film was compact and relatively smooth and infrared spectroscopy suggested the polymer chains were formed mainly via coupling of the unsaturated nitrogen atoms. The polymer was found to be highly electroactive, showing a quasi-reversible and stable pair of redox peaks centering at 0.9 V versus Ag/AgCl in 0.1 mol L⁻¹ H₂SO₄.     

The effects of 4-ethylpyridine and 2-cyanopyridine on zinc electrowinning from acidic sulfate solutions

The effects of 4-ethylpyridine and 2-cyanopyridine on the electrowinning of zinc in the presence and absence of antimony have been studied. The results are compared with those of a common industrial additive, gum arabic. Addition of either compound reduced current efficiency, increased power consumption and lowered the surface quality of electrodeposited zinc. Both the additives showed similar polarization behaviour to gum arabic. Addition of 0.04mgdm–3 antimony increased current efficiency, reduced power consumption and altered the surface morphology and crystallographic orientations. Combinations of antimony with 4-ethylpyridine resulted in very good current efficiencies, and zinc morphology and quality.     

Acidic ionic liquid [bmim]HSO4: An efficient catalyst for acetalization and thioacetalization of carbonyl compounds and their subsequent deprotection

Acetalization/thioacetalization of carbonyl compounds, under solvent free conditions, has been described using acidic ionic liquid 1-Butyl-3-methylimidazolium hydrogen sulfate ([bmim]HSO₄) at room temperature, in conjunction with microwave energy and ammonium chloride. The catalyst retains its acidity, catalytic activity, and recyclability in ammonoium chloride, whereas its decomposition is observed under microwave irradiation. The same catalyst has also been used for the deprotection of acetals, thioacetals as well as for transthioacetalization under microwave irradiation.     

Study on ionic liquid [bmim]PF<Subscript>6</Subscript> and [hmim]PF<Subscript>6</Subscript> as plasticizer for PVC paste resin

Two kinds of room temperature ionic liquids, [bmim]PF₆ (1-butyl-3-methylimidazolium hexafluorophosphate) and [hmim]PF₆ (1-hexyl-3-methylimidazolium hexafluorophosphate), were respectively used as plasticizer for PVC paste resin. The mechanical properties, thermal and ultraviolet ray stabilities, and migration characteristics of the PVC paste resin samples were determined by universal testing machine, TG/DTA, and HPLC. The results showed that the tensile strength and elastic modulus decreased, the elongation at break and thermal stability of PVC paste resin membranes were improved with the increasing of [bmim]PF₆ or [hmim]PF₆ dosages. The immersed time and temperature could accelerate leaching and migration of plasticizers in plasticized PVC paste resin films. Moreover, the effect of solvent environment on migration amount was also studied.     

Microwave-Assisted Esterification of Oleic Acid Using an Ionic Liquid Catalyst

The combination of 1-butyl-3-methylimidazolium hydrogen sulfate ([Bmim]HSO₄) ionic liquid (IL) and microwave heating was used to esterify oleic acid as a green approach in biodiesel synthesis. To compare the heating systems, conventional heating and the ultrasonic method were employed but the microwave method was found to be more effective. H₂SO₄ and 1-methyl imidazole hydrogen sulfate ([Hmim]HSO₄) were also used in the esterification of oleic acid and their catalytic activities were compared to that of [Bmim]HSO₄. ILs provided some advantages such as reusability, easy recyclability, and very stable activity. There was only a small decrease in the catalytic activity of [Bmim]HSO₄ after four successive applications, which means that ILs can be reused, contrary to homogeneous catalysts. The combination of IL catalysts and microwave irradiation proved to be a potential alternative method for biodiesel production.     

Investigating acidic ionic liquid-based ultrasonic-assisted extraction of leonurine from Herba Leonuri

An ultrasonic-assisted extraction (UAE) method based on the acidic ionic liquid (IL) of 1-methyl-3-H-imidazolium hydrogen sulfate ([HMIM][HSO₄]) has been successfully developed to extract leonurine from Herba Leonuri. The results indicate that the acidity of the IL has remarkable effect on the extraction efficiency. In addition, several parameters affecting the extraction efficiency, such as ultrasonic power and time, concentration of IL and solid-liquid ratio, were also optimized. Using the proposed approach, the extraction efficiency of leonurine from Herba Leonuri powder reached 0.136‰ within 30 min using only 20 mL of 1 mol·L^?1 [HMIM][HSO₄] aqueous solution.     

Corrosion inhibition of mild steel by alkylimidazolium ionic liquids in hydrochloric acid

The acid corrosion inhibition process of mild steel in 1 M HCl by 1-butyl-3-methylimidazolium chlorides (BMIC) and 1-butyl-3-methylimidazolium hydrogen sulfate ([BMIM]HSO₄) has been investigated using electrochemical impedance, potentiodynamic polarization and weight loss measurements. Potentiodynamic polarization studies indicate the studied inhibitors are mixed type inhibitors. For both inhibitors, the inhibition efficiency increased with increase in the concentration of the inhibitor and the effectiveness of the two inhibitors are in the order [BMIM]HSO₄ > BMIC. The adsorption of the inhibitors on mild steel surface obeyed the Langmuir's adsorption isotherm. The effect of temperature on the corrosion behavior in the presence of 5 × 10⁻³ M of inhibitors was studied in the temperature range of 303-333 K. The associated activation energy of corrosion and other thermodynamic parameters such as enthalpy of activation (ΔH), entropy of activation (ΔS), adsorption equilibrium constant (K_ads) and standard free energy of adsorption (ΔG_ads) were calculated to elaborate the mechanism of corrosion inhibition.     

Brønsted acidic ionic liquids as novel catalysts for Prins reaction

Prins reaction, used to prepare dioxanes, has been limited by complex catalyst separation and reusability. In this article, six water-stable Brønsted acidic task-specific ionic liquids ([HMIM]BF₄,[(CH₂)₄SO₃HMIM][HSO₄], [(Ac)₂BIM]Br, [NMP][HSO₄], [BMIM][HSO₄] and [BMIM][H₂PO₄] were synthesized and used as environmentally benign catalysts for Prins reaction under mild reaction conditions for the first time. The process is highly effective and environmentally benign. Furthermore, [BMIM][HSO₄] was conveniently separated with the products and easily recycled to catalyze Prins reaction again with excellent yields.     

Ionic liquid effects on the reaction of β-enaminones and tert-butylhydrazine and applications for the synthesis of pyrazoles

In order to evaluate the effect of a series of 10 different ionic liquids ([BMIM][BF₄], [BMIM][Br], [OMIM][BF₄], [BMIM][PF₆], [DBMIM][Br], [DBMIM][BF₄], [BMIM][OH], [BMIM][SCN], [HMIM][HSO₄] and [HMIM][CF₃CO₂]) the cyclocondensation reaction between 4-dimethylamino-1-phenyl-3-alken-2-ones (RC(O)CHCHNMe₂, where R = Ph, 4-Me-Ph, 4-F-Ph, 4-Cl-Ph, 4-Br-Ph, 4-NO₂-Ph, thien-2-yl, fur-2-yl, pyrrol-2-yl, pyrid-2-yl, hexyl, dimethoxymethyl) and tert-butylhydrazine was performed. The effects of each ionic liquid are discussed and the best yields for the cyclocondensation reaction studied were obtained using [BMIM][BF₄].     

Electrochemical behavior of K<Subscript>4</Subscript>Fe(CN)<Subscript>6</Subscript> in [bmim]PF<Subscript>6</Subscript>/TX-100/H<Subscript>2</Subscript>O based microemulsions

The electrochemical behavior of potassium ferrocyanide [K₄Fe(CN)₆] at Pt/ionic liquid (IL) microemulsion interfaces was investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). H₂O/TX-100/bmimPF₆ was used to prepare three IL microemulsions: water in 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF₆) (W/IL), bicontinuous (WIL) and bmimPF₆ in water (IL/W). The results show that the IL microemulsion systems have relatively narrower potential windows compared with the pure IL system. The redox potential gap is about 100 mV in the pure water and the three IL microemulsions. The redox potentials of K₄Fe(CN)₆/K₃Fe(CN)₆ and the redox peak currents decrease in the order pure water, IL/W, WIL, W/IL. Furthermore, the peak currents increase linearly with the square root of the scan rate, while the diffusion coefficient increased in the order W/IL, WIL, IL/W. The Nyquist plots obtained in the WIL and IL/W systems show capacitive resistance arcs at high frequencies and 45° straight lines at low frequencies, implying that the electrochemical reactions are controlled by charge transfer and diffusion steps. For the W/IL system there is only a 45° straight line in the Nyquist plot, indicating that diffusion is the controlling step at all frequencies.     

Preparation and electrochemical properties of spherical LiFePO<Subscript>4</Subscript> and LiFe<Subscript>0.9</Subscript>Mg<Subscript>0.1</Subscript>PO<Subscript>4</Subscript> cathode materials for lithium rechargeable batteries

The spherical LiFePO₄/C and LiFe_0.9Mg_0.1PO₄/C powders were successfully prepared from spherical FePO₄ via a simple uniform-phase precipitation method at normal pressure, using FeCl₃ and H₃PO₄ as the reactants. The FePO₄, LiFePO₄/C, and LiFe_0.9Mg_0.1PO₄/C powders were characterized by scanning electron microscopies (SEM), powder X-ray diffraction (XRD), X-ray photoelectron spectrometer (XPS), and tap-density testing. The uniform spherical particles produced are amorphous, but they were crystallized to FePO₄ after calcining above 400 °C. Due to the homogeneity of the basic FePO₄, the final products, LiFePO₄/C and LiFe_0.9Mg_0.1PO₄/C, are also significantly uniform and the particle size is of about 1 μm in diameter. The tap-density of the spherical LiFePO₄/C and LiFe_0.9Mg_0.1PO₄/C are 1.75 and 1.77 g cm⁻³, respectively, which are remarkably higher than the non-spherical LiFePO₄ powders (the tap-density is 1.0–1.3 g cm⁻³). The excellent specific capacities of 148 and 157 mAh g⁻¹ with a rate of 0.1 C are achieved for the LiFePO₄/C and LiFe_0.9Mg_0.1PO₄/C, respectively. Comparison of the cyclic voltammograms of LiFePO₄/C and LiFe_0.9Mg_0.1PO₄/C shows enhanced redox current and reversibility for the sample substituting Mg on the Fe site. LiFe_0.9Mg_0.1PO₄/C exhibits better high-rate and cycle performances than the un-substituted LiFePO₄/C.     

Effects of 2-picoline on zinc electrowinning from acidic sulfate electrolyte

The behaviour of 2-picoline with and without antimony during electrowinning of zinc from acidic sulfate solutions was studied and was compared with that of gum arabic which is commonly used in industry as a levelling agent. The effects of these additives on current efficiency, power consumption, deposit quality, polarization behaviour, crystallographic orientation and surface morphology were determined. The addition of 2-picoline reduced current efficiency, increased power consumption and lowered the surface quality of electrowon zinc. Addition of antimony increased current efficiency, reduced power consumption and produced improved surface morphology and crystal orientations, (101) (112) (102) (103) (114) over a wide range of their combinations.     

Chemical and electrochemical characterization of TiO<Subscript>2</Subscript>/Al<Subscript>2</Subscript>O<Subscript>3</Subscript> atomic layer depositions on AZ-31 magnesium alloy

In this study, innovative TiO₂/Al₂O₃ mono/multilayers were applied by atomic layer depositions (ALD) on ASTM-AZ-31 magnesium/aluminum alloy to enhance its well-known scarce corrosion resistance. Four different configurations of ALD layers were tested: single TiO₂ layer, single Al₂O₃ layer, Al₂O₃/TiO₂ bilayer and Al₂O₃/TiO₂/Al₂O₃/TiO₂ multilayer deposited using Al[(CH₃)]₃ (trimethylaluminum, TMA), and TiCl₄ and H₂O precursors. All depositions were performed at 120°C to obtain an amorphous-like structure of both oxide layers. The four coatings were then investigated using different techniques, such as scanning electron microscope (SEM), stylus profilometer, glow discharge optical emission spectrometry (GDOES) and polarization curves in 0.05-M NaCl solution. The thickness of all the coatings was around 100 nm. The layers compositions were successfully investigated by the GDOES technique, although obtained data seem to be affected by substrate roughness and differences in sputtering rates between ceramic oxides and metallic magnesium alloy. Corrosion resistance showed to be strongly enhanced by the nanometric coatings, giving lower corrosion current densities in 0.05-M NaCl media with respect to the uncoated substrate (from 10⁻⁴ to 10⁻⁶ A/cm² for the single layers and from 10⁻⁴ to 10⁻⁸ A/cm² for the bi- and multilayers). All polarization curves on coated samples also showed a passive region, wider for the bi-layer (from −0.58 to −0.43 V with respect to Ag/AgCl) and multilayer (from −0.53 to −0.38 V with respect to Ag/AgCl) structures.