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.     

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.     

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.     

Effects of [HMIM]HSO<Subscript>4</Subscript> and [OMIM]HSO<Subscript>4</Subscript> on the electrodeposition of zinc from sulfate electrolytes

The effects of the organic additives 1-hexyl-3-methylimidazolium hydrogen sulfate ([HMIM]HSO₄) and 1-octyl-3-methylimidazolium hydrogen sulfate ([OMIM]HSO₄) on current efficiency (CE), power consumption (PC), polarization behavior of the cathode, deposit morphology, and crystallographic orientation during electrodeposition of zinc from acidic sulfate solution were investigated. The results were compared with those of a common industrial additive, gum arabic. Addition of these additives increases current efficiency, decreases power consumption, and improves the surface morphology at lower concentrations. Both the additives showed similar polarization behavior to gum arabic and the extent of polarization was in the order: gum arabic > [OMIM]HSO₄ > [HMIM]HSO₄. The nature of the electrode reactions was studied through measurements of Tafel slopes, transfer coefficients, and exchange current densities. Data obtained from X-ray diffractogram revealed that the presence of any of these additives did not change the structure of the electrodeposited zinc but affected the crystallographic orientation of the crystal planes.     

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.     

Influence of pulse plating parameters on the synthesis and preferred orientation of nanocrystalline zinc from zinc sulfate electrolytes

The influence of pulse electrodeposition parameters (current on-time T_on, current off-time T_off, and pulse current density J_p) was investigated on the surface morphology and grain size of zinc electrodeposited from a sulfate bath containing polyacrylamide and thiourea additives. The grain size and surface morphology of zinc deposits were studied by field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM), and the preferred orientation of the deposits was studied by X-ray diffraction. At constant current off-time and pulse current density, the grain size decreased asymptotically with increasing current on-time. In contrast, increase in the current off-time at constant current on-time and pulse current density resulted in grain growth. A progressive decrease of the grain size was observed with increasing pulse current density at constant current on-time and off-time. Nanocrystalline zinc with an average grain size of 38 nm was obtained at a pulse current density of 1200 mA/cm². The crystallographic orientations developed were correlated with the change in the cathodic overpotential, the angle between the preferred oriented plane and the lowest energy of formation plane (0 0 0 2), and the pulse electrodeposition parameters.     

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].     

Chromium electrodeposition from [BMIm][BF<Subscript>4</Subscript>] ionic liquid

The electrodeposition of black chromium coatings from ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate with chromium chloride, and the chemical composition of the deposits are discussed in this article. The UV–Vis spectra recorded for chromium(III) species in 1-butyl-3-methylimidazolium tetrafluoroborate suggest that along with the chromium(III) complexes containing three ligands, there are some amounts of chromium species containing four ligands in the bath employed. The cathodic process of chromium electrodeposition in the employed ionic liquid is complicated by the electrochemical reduction of water molecules, which is followed by chemical disintegration of tetrafluoroborate ions. The surface morphology of black chromium films deposited potentiostatically (–1.5 to −2.0 V) at 85 °C shows nodules and microcracks increasing in size with cathodic potential. Analysis of the X-ray photoelectron spectra recorded from surface to depth of the deposit has shown that the black oxide-rich chromium coating consists of chromium in both oxide and metallic states with small impurities of other elements (fluorine, boron, carbon and nitrogen) and the surface is covered with a thin layer of organic substances. The results of this study show that 1-butyl-3-methylimidazolium tetrafluoroborate may be considered as a promising substitute of toxic Cr(VI) baths for black chromium plating.     

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].     

Functionalized Ionic Liquid-Catalyzed 1-Feruloyl-sn-glycerol Synthesis

Feruloyl Glycerol (FG) is a potential antioxidant and UV absorbing ingredient in food and cosmetic industries. Transesterifications of ethyl ferulate (EF) with glycerol to synthesize FG were performed using different functionalized ionic liquids (1‐butylsulfonic‐3‐methylimidazolium tosylate, [BSO₃HMIM]TS; 1‐propylsulfonic‐3‐methylimidazolium tosylate, [PSO₃HMIM]TS; 1‐butylsulfonic‐3‐methylimidazolium trifluoromethanesulfonate, [BSO₃HMIM]OTF; 1‐butylsulfonic‐3‐methylimidazolium hydrogen sulfate, [BSO₃HMIM]HSO₄; N‐methylimidazolium hydrogen sulfate, [HMIM]HSO₄; 1‐butyl‐3‐methylimidazolium hydroxide, [BMIM]OH; 1‐butyl‐3‐methylimidazo tetrachloride molysite, [BMIM]FeCl₄; and 1‐hexyl‐3‐methylimidazo tetrachloride molysite, [BMIM]FeCl₄) as catalysts, respectively. High EF conversion (98.0 ± 1.5 %), 1‐FG (1‐feruloyl‐sn‐glycerol) yield (88.7 ± 1.1 %) and reaction selectivity for 1‐FG (90.5 ± 2.1 %) were obtained using [BSO₃HMIM]TS as catalyst. The activation energy (E_a), the Michaelis–Menten kinetic constant (K_m), and the maximum initial reaction rate (v_max) of the transesterification are 65.9 ± 3.3 kJ/mol, 1.8 ± 0.1 mol/L, and (1.6 ± 0.4) × 10^?2 mol/(L min), respectively. Effects of catalyst loading, reaction temperature, and the molar ratio of EF to glycerol on EF conversion and reaction selectivity for 1‐FG (1‐FG yield/EF conversion) were also investigated.     

Electrodeposition of zinc-nickel alloy coatings from a chloride bath containing NH4Cl

Zinc-nickel alloys were electrodeposited on steel from chloride baths containing NH₄Cl using different plating conditions. Current density, temperature and nickel percentage in the baths were found to strongly influence the composition of the deposits and the morphology. At low current densities transition from anomalous to normal codeposition was observed. The changes in potential, current efficiency, composition and morphology which follow the transition were studied. No increase in the partial current of hydrogen reduction was observed at the potential values from which anomalous codeposition begins; this fact, plus the formation of zinc ammonium complexes, seems to exclude the precipitation of zinc hydroxide at the electrode surface. The electrodeposition of zinc-nickel alloys is discussed emphasizing the importance of kinetic parameters and cathodic potentials.     

Simple, efficient and recyclable palladium catalytic system for Heck reaction in functionalized ionic liquid network

In functionalized ionic liquid network of [BMIM][TPPMS] and [BMIM][OAc], PdCl₂(CH₃CN)₂ efficiently catalyzed the Heck reaction of bromobenzene to ethyl cinnamate with yield of 60% and without the activity loss even after 11 recycling uses. The beneficial influences of this ionic liquid network on activity and stability were explained in terms of synergic ligand effects of [BMIM][TPPMS] and [BMIM][OAc], no accumulation of sodium or ammonium bromides by using [BMIM][OAc] as base, and the positive effect of [BMIM]Br by avoiding the formation of palladium black. The generality of this ionic liquid system to the different substrates also gave the pleasing results.     

Influence de l'antimoine et du cuivre sur la cementation du cobalt par le zinc

Zinc sulphate solution (160g/l Zn²⁺) used for zinc electrowinning is purified for cobalt by cementation with metallic zinc powder. Industrial practice shows that considerable acceleration of this operation is achieved by the presence of trace impurities in solution. Eventually, CuSO₄ and Sb₂O₃ are deliberately added to the solution. The aim of this work is to elucidate the mechanism of action of those impurities.Zn²⁺ ions present in the solution are responsible for the slow speed of cobalt deposition (160g/l Zn²⁺; 10 mg/l Co²⁺).The cathodic part of the cementation reaction was simulated on a flat electrode through potentiostatic deposits at ?730 mV/ENH (potential at zero current of metallic zinc in the solution). The deposits were studied by anodic dissolution, radioactive tracers, X-ray diffraction and fluorescence, atomic absorption spectrophotometry, optical and electronic microscopy (transmission and scanning). The results were compared with cementation on zinc plate and zinc powder.Antimony and copper are deposited together with cobalt and form alloys with reduced cobalt activity. Total voltage available to overcome the inhibitor effect of zinc ions is thus increased and the reduction of cobalt ions accelerated. Antimony, copper and cobalt triple alloys resist particularly well to corrosion with hydrogen evolution. Copper has a higher accelerating effect on cobalt cementation than antimony, but the latter stabilizes the deposit very effectively.The electrochemical methods used and the knowledge of the mechanism of action of the impurities open new trends for industrial practice.     

The effect of thiourea on zinc electrowinning from industrial acid sulphate electrolyte

The effect of thiourea, with and without glue and antimony additions, on the current efficiency (CE) and polarization behaviour of zinc deposition and on the morphology and preferred orientation of the zinc deposits electrowon (at 430 A m^–2 and 35°C) from industrial acid sulphate electrolyte (55 g l^–1 Zn and 150 g l^–1 H₂SO₄) has been determined. Increasing concentrations of thiourea in the electrolyte decreased the CE for zinc deposition; the additional presence of antimony did not significantly alter the decrease in CE but the presence of glue resulted in a further substantial decrease in CE. Thiourea changed the zinc deposit morphology and orientation, and also altered the shape of the zinc deposition cyclic voltammogram.     

Alkoxyl side-chain effects of acidic ionic liquids catalysts for the esterification of n-butyl butyrate

Three kinds of alkoxy group-functionalized acidic ionic liquids (ILs) are reported in this work, namely, 1-(methoxyethyl)-3-methylimidazolium hydrogen sulphate [MOE-MIM]HSO₄, 1-(ethyoxyethyl)-3-methylimidazolium hydrogen sulphate [EOE-MIM]HSO₄, and 1-(propyoxyethyl)-3-methylimidazolium hydrogen sulphate [POE-MIM]HSO₄. The short side chain on the cation of [MOE-MIM]HSO₄ decreases the solubility of the IL in butanol and butyric acid and facilitates the separation of the IL from a reaction medium. The yield of butyl butyrate is up to 99.5%. After 10 rounds of recycling, the catalytic performance of [MOE-MIM]HSO₄ shows no significant changes.     

Preparation of well-defined dendrimer encapsulated ruthenium nanoparticles and their application as catalyst and enhancement of activity when utilised as SCILL catalysts in the hydrogenation of citral

Silica supported dendrimer encapsulated ruthenium nanoparticles were prepared and evaluated as catalysts in the hydrogenation of citral. The dendrimer encapsulated nanoparticles were prepared using the generation 4 (G4), generation 5 (G5) and generation 6 (G6) hydroxyl-terminated poly(amidoamine) (PAMAM-OH) dendrimers as templating agents with different Ru metal:dendrimer ratios. The effects of ionic liquids as catalyst coatings on the catalytic activity were investigated for the ionic liquids [BMIM][NTf₂], [OMIM][NTf₂], [BMIM][BF₄], [BMIM][PF₆], [EMIM][OcS] and [EMIM][EtS]. An enhancement in catalytic activity was observed when utilising [BMIM][NTf₂] as an ionic liquid coating with selectivity towards citronellal.     

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.     

Electropolymerization of pyrrole in ionic liquid microemulsion

The direct electropolymerization of pyrrole in [BMIM]PF₆ microemulsion was investigated for the first time. The H₂O/TX-100/[BMIM]PF₆ (W/IL), bicontinuous (BC), [BMIM]PF₆/TX-100/H₂O (IL/W) subregions can be used as electrolytes for pyrrole electropolymerization. The use of IL microemulsion remarkably reduces the amount of IL. Furthermore, electrochemical measurements indicated that W/IL microemulsion was the optimal medium and its polymerization rate was the fastest. Compared with molecular solvent system (0.25 mol L⁻¹ [BMIM]PF₆/acetonitrile) and neat [BMIM]PF₆, the resultant films electrodeposited in W/IL microemulsion possessed excellent electrochemical activity and uniform morphology. All the results indicated that the H₂O/TX-100/[BMIM]PF₆ microemulsion as electrolyte medium is the most suitable for electropolymerization of pyrrole. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

磺酸功能化离子液体催化甘油与甲醇醚化反应

考察了[HSO₃-bmim]CF₃SO₃、[HSO₃-bmim]P-TSA、[HSO₃-bmim]HSO₄和[HSO₃-bmim]H₂PO₄四种磺酸功能化离子液体对甘油与甲醇醚化反应的影响。结果表明,离子液体的催化性能与其酸强度相关联,[HSO₃-bmim]CF₃SO₃离子液体的酸强度最强,其催化性能也最好。以[HSO₃-bmim]CF₃SO₃为催化剂,在w([HSO₃-bmim]CF₃SO₃)/w(甘油)=0.5:1(质量比)、n(甲醇)/n(甘油)=8:1(摩尔比)、反应温度190℃、反应时间8 h时,甘油的转化率为84.5%,单甲基甘油醚的选择性为41.4%,二甲基甘油醚和三甲基甘油醚的联合选择性为34.1%。在此基础上,提出了离子液体[HSO₃-bmim]CF₃SO₃催化甘油与甲醇醚化反应的反应机理。