Investigation of the electro-oxidation of artificial Black Sea water using cyclic voltammetry on metal sulfide electrodes (I)

Black Seawater is an alternative hydrogen source because it has hydrogen sulfide content. Seawater electrolysis is a promising method to produce hydrogen. The anodic oxidation of hydrogen sulfide is a novel approach for directly generating electricity via fuel cells. Therefore, four materials (Cu, Stainless Steel 304 (SS), V₂O₅ and Ni) were examined in artificial seawater containing hydrogen sulfide (HS⁻). We developed active metal sulfide electrodes for oxidizing HS⁻. Alongside the corrosion potentials, the progression of the oxidation and reduction reactions was obtained by the cyclic voltammetry method. The active behaviors of the metal sulfide (MS_x) layers were determined by applying Electrochemical Impedance Spectroscopy (EIS). Although the Cu₂S electrode acts as the active catalyst during HS⁻ ion oxidation, NiS is the most suitable metal sulfide because it exhibits a higher corrosion resistance than Cu₂S. While V₂O₅ demonstrates catalytic activity at high temperatures (≥30 °C), FeS layers corrode easily in the artificial seawater environment.     

Application of Different Multi-criteria Decision Techniques to Determine Optimum Flavour of Prebiotic Pudding Based on Sensory Analyses

The selection of optimum aroma among vanilla, strawberry and cacao for prebiotic pudding was aimed based on sensory analyses by performing multi-criteria decision techniques [analytic hierarchy process (AHP), simple additive weighting (SAW), technique for order preference by similarity to ideal solution (TOPSIS) and elimination et choix traduisant la realite-elimination and choice translating reality (ELECTRE)]. In the first part of the study, the physicochemical (pH, viscosity, dry matter and ash content) and functional properties (bulk density, water-holding capacity and oil-holding capacity) of the dietary fibres (lemon, inulin, apple and wheat) were determined. According to our results, there are significant differences between the fibres (P?<?0.05). In the second part of the study, the INU/OLI dietary fibre was added to the different flavoured pudding samples (cacao, strawberry and vanilla). Some of their physicochemical (bulk density, dry matter and viscosity) and sensorial properties (appearance, consistency of appearance, consistency in the mouth, taste and smell, adhesiveness and general acceptability) were identified. In the last part of the study, multi-criteria decision techniques (AHP, SAW, ELECTRE and TOPSIS) were applied to obtain the ranking of the pudding samples based on the sensorial scores. According to the results of this study, strawberry-flavoured pudding (not including fibre) was mostly preferred. By considering the ranking of the puddings, it was seen that strawberry flavour was the most appropriate for prebiotic pudding. As a result of this study, it was found that multi-criteria decision techniques may be performed to sensorial scores in the food industry to reduce many results to one result thus facilitating the comparison of samples and the explication of results obtained from sensory analysis.     

A novel two‐part interconnector for solid oxide fuel cells

A two‐part interconnector is developed for solid oxide fuel cell stacks to reduce cost and to improve sealing. The novel interconnector involves a metallic core for current collection and gas distribution and a ceramic support to house the metallic core and to separate two short stacks. The new interconnector reduces usage of expensive metallic alloys and substantially reduce mismatch between stack components due to higher expansion coefficient of metals. The new interconnectors also improve sealing with glass–ceramics eliminating chromium evaporation which is a major reason for sealing failure in fully metallic interconnectors. A proof of concept short stack is manufactured and tested in this study. A comparable performance with a convectional interconnector is obtained with new interconnector, while substantially improving the sealing quality. Copyright © 2014 John Wiley & Sons, Ltd.     

The synthesis and characterization of 2-(2′-pyridyl)benzimidazole heteroleptic ruthenium complex: Efficient sensitizer for molecular photovoltaics

The novel ligand 1-(2,4,6-trimethylbenzyl)-2-(2′-pyridyl)benzimidazole and its heteroleptic ruthenium (II) complex were synthesized. The complex was characterized using spectroscopic methods and cyclic voltammetry. Charge-separation was investigated within nanoporous titanium dioxide employing surface photovoltage spectroscopy. The performance of the ruthenium complex as a charge transfer photosensitizer in nanocrystalline, titanium dioxide-based, dye sensitized solar cells was studied under standard AM 1.5 sunlight using an electrolyte consisting of 0.6 M 1-butyl-3-methyl-imidazolium iodide, 0.1 M lithium iodide, 0.05 M iodine and 0.5 M 4-tert-butyl pyridine in 3-methoxy propyonitrile. The novel complex had a photocurrent density of 9.47 mA cm⁻², 600 mV open circuit potential and 0.60 fill factor yielding an efficiency of 3.4%. The photovoltaic performance of the colorant was compared with that of cis-bis(isothiocyanato)(2,2'-bipyridyl-4,4'-dicarboxylato) (2,2’-bipyridyl-4,4’-di-nonyl) ruthenium(II); both compounds exhibited similar efficiency, while the fill factor value was higher for the novel dye.     

Effect of temperature and starch concentration on the creep/recovery behaviour of the grape molasses: modelling with ANN, ANFIS and response surface methodology

In this study, the effect of starch concentration (5, 7.5 and 10 %) and temperature (60, 70 and 80 °C) on the creep and recovery behaviour of grape molasses was investigated. Adaptive neuro-fuzzy inference system (ANFIS) and artificial neural network (ANN) models were established for the prediction of the compliance values (J(t)) based on temperature, starch concentration and time of the creep or recovery phases. The root mean square error, mean absolute error and R ² values were used for the comparison of the models which showed that the ANFIS model performed better than the ANN model for the desired purpose. The Burger model fitted the J(t) versus time data with R ² values ranging from 0.987 to 0.999. Response surface methodology (RSM) was performed to investigate the dependency of the creep (G ₀ , G ₁ , n ₀ and n ₁ ) and recovery (J _KV , B, C, J _max , J _∞ and  % recovery) parameters to temperature and starch concentration. As a result of this study, it was observed that deformation of the grape molasses samples increased with decrease in starch concentration and increase in temperature. The gel strength (S) values of the samples were also calculated and modelled by RSM. As increase in starch concentration caused an increase in S value, there was an inverse proportion between the temperature and S value.     

The effects of microwave power and dielectric properties on the microwave-assisted decomposition kinetics of AIBN in n-butanol

The effects of microwave power and solvent–reactant dielectric properties on the kinetics of the decomposition of AIBN in n-butanol were investigated. According to the kinetic data, k increases with increasing microwave power, the dependence becomes stronger at high temperature. The Arrhenius parameters (E_a,mw, k_0,mw) were higher than thermal counterparts. To elucidate the nature of microwave effect on chemical reactions, various models to relate the Arrhenius parameters to temperature, microwave power and the dielectric properties of the reaction medium were developed, nonlinear regression analysis was performed to estimate the model parameters and statistical analysis was conducted for model evaluation.     

Effects of electrolyte pattern on mechanical and electrochemical properties of solid oxide fuel cells

In order to enhance the electrochemical performance and reduce the operation temperature of a conventional electrolyte supported solid oxide fuel cell (SOFC), a three layered electrolyte with various geometry is designed and fabricated. Novel three layered electrolytes comprise a dense and thin scandia alumina stabilized zirconia (ScAlSZ) electrolyte layer sandwiched between two hallow ScAlSZ electrolyte layers each having the same thickness as the support but machined into a filter like architecture in the active region with circular, rectangular and triangular cut off patterns. The percent of thin electrolyte layer in the active region is kept constant as 30% for all designs in order to investigate the effect of pattern geometry on the mechanical properties and the performance of the electrolytes. Single cells based on novel electrolytes are manufactured and electrochemical properties are evaluated. A standard electrolyte and electrolyte supported cell are also fabricated as a base case for comparison. Although the electrolyte having triangular patterns has the highest peak power at all operation temperatures considered, it exhibits the lowest flexural strength.     

Treatment of poultry slaughterhouse wastewaters by electrocoagulation

Treatment of poultry slaughterhouse wastewater (PSW) by electrocoagulation (EC) has been investigated batchwise in this paper. Effects of the process variables such as medium pH, electrode material, current density, and operating time are investigated on chemical oxygen demand (COD) and oil-grease removal efficiencies, electrical energy consumption, and sacrificial electrode consumption. The highest COD removal efficiency is reached with aluminum as 93%, and maximum oil-grease removal is obtained with iron electrodes as 98%. Combined use of both electrode materials in the EC unit may yield high process performances with respect to both COD and oil-grease removals. Further work needs to be carried out at pilot scale to assess the technical end economic feasibility of the process.     

Contact time optimization of two-stage batch adsorber design using second-order kinetic model for the adsorption of phosphate onto alunite

The adsorption of phosphate onto alunite in a batch adsorber has been studied. Four kinetic models including pseudo first- and second-order equation, intraparticle diffusion equation and the Elovich equation were selected to follow the adsorption process. Kinetic parameters, rate constants, equilibrium adsorption capacities and related correlation coefficients, for each kinetic model were calculated and discussed. It was shown that the adsorption of phosphate onto alunite could be described by the pseudo second-order equation. Adsorption of phosphate onto alunite followed the Langmuir isotherm. A model has been used for the design of a two-stage batch adsorber based on pseudo second-order adsorption kinetics. The model has been optimized with respect to operating time in order to minimize total operating time to achieve a specified amount of phosphate removal using a fixed mass of adsorbent. The results of two-stage batch adsorber design studies showed that the required times for specified amounts of phosphate removal significantly decreased. It is particularly suitable for low-cost adsorbents/adsorption systems when minimising operating time is a major operational and design criterion, such as, for highly congested industrial sites in which significant volume of effluent need to be treated in the minimum amount of time.     

Treatment of dairy wastewaters by electrocoagulation using mild steel electrodes

The removal of COD and oil-grease from dairy wastewater was experimentally investigated using direct current (DC) electrocoagulation (EC). In the EC of dairy wastewater, the effects of initial pH, electrolysis time, initial concentration of COD, conductivity and current density were examined. The COD and oil-grease in the aqueous phase were effectively removed when iron was used as sacrificial anode. The optimum operating range for each operating variable was experimentally determined. The batch experimental results revealed that COD and oil-grease in aqueous phase was effectively removed. The overall COD and oil-grease removal efficiencies reached 98 and 99%, respectively. The optimum current density, pH and electrolysis time for 18,300 mg COD/L and 4570 mg oil-grease/L were 0.6 mA/cm2, 7 and 1 min, respectively. Mean energy consumption was 0.003 kWh/kg of COD.