Optimization Of Operating Conditions Research Articles

Heterogeneous Aqueous CO2 Reduction Using a Pyrene-Modified Rhenium(I) Diimine Complex.

The development of molecular catalysts and materials that can convert carbon dioxide (CO2) into a value-added product is a great chemical challenge. Molecular catalysts set benchmarks in catalyst investigation and design, but their incorporationinto solid-state materials, and optimization of the electrochemical operating conditions, is still needed. For example, rhenium(I) diimine catalysts show almost quantitative selectivity for the conversion of CO2 to carbon monoxide (CO) in acetonitrile (MeCN), but the modification of diimine backbones can be challenging if the goal is to incorporate such molecules into materials. Presented here is a rhenium(I) complex with a 2-(2'-quinolyl)benzimidazole (QuBIm-H) ligand, where N-alkylation with a pyrene derivative allows access to a catalyst that can be adsorbed onto electrodes for aqueous CO2 reduction chemistry. The rhenium(I) catalysts are inactive for homogeneous CO2 reduction in MeCN. However, when adsorbed on edge-plane graphite, the same complexes show good activity for heterogeneous aqueous CO2 reduction, with 90% selectivity for CO. Comparative electrochemical studies between covalent and noncovalent modification of the graphite surfaces were also carried out for related rhenium(I) tricarbonyl complexes.

Quantitative analysis of trace- and ultratrace-level Dimethylsilanediol (DMSD) in water, soil, sediment and biosolids by liquid chromatography-triple quadrupole tandem mass spectrometry

ABSTRACTDimethylsilanediol (DMSD) is a highly water-soluble degradation product of dimethylsiloxane oligomer and polymer materials that may be found in the environment. In this project, we have developed a water analysis method for DMSD based on liquid chromatography-triple quadrupole tandem mass spectrometry (LC/QQQ MS/MS) using 13C-DMSD as an internal standard with and without solid phase extraction (SPE). This included the modification of SPE extraction method for water samples with colloidal particles that may plug the SPE cartridge, the use of a water-based solvent mixture for DMSD elution to promote better ionisation in instrumental analysis and optimisation of instrumental operation conditions for higher sensitivity in QQQ MS/MS analysis. The water method was successfully applied for analysis of DMSD in soil, sediment and biosolids by coupling the water extraction of DMSD from solid samples with the pre-column SPE extraction of the water extracts. The method detection limit (MDL) for direct water analysis was found to be as low as 2 μg L−1, while the current MDLs for sediment, soil and biosolids are in the range of 10 to 100 ng g−1 dw. The matrix spike recovery varied from 79% to 99% for all samples, confirming its general validity of the method. Compared with the published methods, this method requires less sample processing and has lower MDLs for DMSD analysis in environmental samples.

Optimization of Oleuropein and Luteolin-7-O-Glucoside Extraction from Olive Leaves by Ultrasound-Assisted Technology

The olive orchard cultivation in Mediterranean countries results in huge amounts of lignocellulosic biomass residues. One of the main residues are olive leaves. Olive leaves contain high concentrations of bioactive antioxidant compounds like oleuropein and luteolin-7-glucoside. The production of biactive compounds from olive leaves requires treatments capable of breaking the lignocellulosic structure. Current research focuses on use of inexpensive, quick, and not harmful to the environment treatments, searching a more simplified large-scale operation approach. Recently, advances in applied chemistry have led to possible new emerging industrial techniques like ultrasound-assisted extraction (UAE). This technology is a promising candidate as a green treatment solution for olive leaves utilization in a biorefinery. However, this application goes through prior optimization of technique and operating conditions. The goal of this study was to optimize the extraction of oleuropein and luteolin-7-glucoside from olive leaves through an investigation of the influence of key factors of ultrasound-assisted extraction using an experimental central composite design, in comparison with conventional Soxhlet extraction. The highest extraction efficiency and antioxidant capacity were obtained under optimal increment of temperature and amplitude conditions (40 °C and 30%, respectively). Values for oleuropein, luteolin-7-glucoside were 69.91 g/kg and 1.82 g/kg, respectively.

Application of Biochar Derived from Different Types of Biomass and Treatment Methods as a Fuel Source for Direct Carbon Fuel Cells

The direct carbon fuel cell (DCFC) is an emerging technology for energy production. The application of biomass in DCFCs will be a major transition from the use of coal to generate energy. However, the relationship between biomass or biochar composition and the electrochemical performance of a DCFC is yet to be studied. The performance of a DCFC using fuel sources derived from woody and non-woody biomass were compared in this study. The effect of pyrolysis temperature ranges from 550 °C to 850 °C on the preparation of biochar from rubber wood (RW) and rice husk (RH) were evaluated for power generation from DCFCs. In addition, the effect of applying chemical pre-treatment and post-treatment on biochar were further investigated for DCFC performance. In general, the power density derived from rubber wood biochar is significantly higher (2.21 mW cm−2) compared to rice husk biochar (0.07 mW cm−2). This might be due to the presence of an oxygen functional group, higher fixed carbon content, and lower ash content in rubber wood biochar. The acid and alkaline pre-treatment and post-treatment have altered the composition with a lower ash content in rubber wood biochar. The structural and compositional alterations in alkaline pre-treatment bring a positive effect in enhancing the power density from DCFCs. This study concludes that woody biochar is more suitable for DCFC application, and alkaline pre-treatment in the preparation of biochar enhances the electrochemical activity of DCFC. Further investigation on the optimization of DCFC operating conditions could be performed.

Optimization of Design Parameters and Operating Conditions of Electrochemical Capacitors for High Energy and Power Performances

Theoretical expressions for performance parameters of different electrochemical capacitors (ECs) were optimized by writing MATLAB scripts to solve them and also via MATLAB R2014a optimization tool box. Performance of different kind of ECs at given circumstances were compared through theoretical equations and simulation of various models subject to conditions of device components, using optimal coefficient associated to battery-kind material and constant associated to electrolyte material KBMopt and KEopt , as well as our symmetric electric double layer capacitor (EDLC) experimental data. Estimations of performance parameters were feasible and achievable once details of electrodes mass ratio, operating potential range ratio and specific capacitance of electrolyte are known. Performances of asymmetric EC with suitable electrode mass and operating potential range ratios using aqueous electrolytes, and that with suitable electrode mass and operating potential range ratios using organic electrolyte with appropriate operating potential range and specific capacitance were factors of 2.2 and 5.56, respectively, greater than those of symmetric EDLC and asymmetric EC using the same aqueous electrolyte, respectively. This enhancement came along with reduction in cell mass and volume. Also, storable and deliverable energies of asymmetric EC with suitable electrode mass and operating potential range ratios using proper organic electrolyte were factor of 12.9 greater than those of symmetric EDLC using aqueous electrolyte, with reduction in cell mass and volume. Storable energy, energy density and power density of asymmetric EDLC with suitable electrode mass and operating potential range ratios using proper organic electrolyte were factor of 5.56 higher than those of similar symmetric EDLC using aqueous electrolyte with reduction in cell mass and volume by a factor 1.77. Also, introduction of asymmetric EDLC with the same type of electrode, and suitable electrodes mass ratio, working potential range ratios and proper organic electrolyte enhanced performance of conventional symmetric EDLC using aqueous electrolyte with reduction in cell mass and volume. These results can obviously reduce number of experiments to determine optimum manufacturing state of EC, and also demonstrated that institution of asymmetric electrode and organic electrolyte was very successful in improving performance of EC with reduction in cell mass and volume. These results can as well be a guideline for design, fabrication and operation of electrochemical capacitor with outstanding storable energy, energy and power densities. Key words: Electrodes symmetry; Modelling and simulation; Performance parameters; Electrolytes type; Working potential range; Asymmetric capacitors.

Optimization and influence of multi-hollow surface dielectric barrier discharge plasma operating conditions on the physical quality of peanut

An experiment was conducted to investigate the effects of atmospheric pressure plasma generated by multi-hollow surface dielectric barrier discharges on physical quality of peanut (Arachis Hypogea L). Multi-hollow surface dielectric barrier discharge is a novel plasma device applicable in food industry applications due to the capacity of the generated plasma to treat the surface of food without changing the quality. Response surface methodology was used to optimize the plasma treatment for surface treatment as raw peanut forms over a range of power (10–40 W), air flow rate (0.5–20 L/min) and time (1–15 min). The weight loss, hardness, contact angle, color parameters, microstructure, and sensory quality evaluation were evaluated during plasma treatments and modeled by response surface methodology and compared the means. Second order polynomial model adequately described the plasma treated experimental data except for sensory attributes with an insignificant lack of fit (p > 0.05). The result revealed that extreme conditions caused a decrease in L*,b*, hardness, contact angle, increased weight loss, color change and changed the microstructure of the treated peanuts.

Extraction of oleuropein and luteolin-7-O-glucoside from olive leaves: Optimization of technique and operating conditions

Olive leaves have become a promising source of phenolic compounds and flavonoids with high added value. Phenolic compounds and flavonoids are important sources of antioxidants and bioactives, and one of the processes used to effectively produce them is extraction via solvents, using aqueous ethanol solutions. To obtain the highest extraction yield per kg of biomass, olive leaves were extracted using a conventional technique (dynamic maceration) and an emerging technology, such as pressurized liquid extraction. Studies of the factors that influence these processes were performed: temperature, leaf moisture content, solvent/solid, and aqueous ethanol concentration were optimized using the central composite and Box-Behnken experiment designs. Pressurized liquid extraction resulted in more efficient oleuropein and luteolin-7-O-glucoside extraction than dynamic maceration. The operational conditions for maximizing the recovery of phenolic compounds and flavonoids and antioxidant capacity were determined to be 190 °C, leaf moisture content of 5%, and aqueous ethanol concentration of 80%.

Continuous electrochemical reactor improved by the addition of Moringa oleífera lam extract: optimization of operational conditions for Blue 5G dye removal

Wastewaters from textile industries are known for their difficulty to treat, several alternative technologies are applied for their treatment. In this context, the study examined a hybrid treatment system, composed of electrocoagulation combined with a natural coagulant (extract of Moringa oleífera lam seeds) to remove reactive dye Blue 5G aqueous solutions. The work evaluated the use of milder operating conditions to improve the efficiency of treatment, with reduced demands for electrical power and coagulant. The following factors were evaluated: electric current intensity, natural coagulant concentration and hydraulic retention time. A quadratic model was adjusted and validated at a 5% significance level. The overall optimization resulted in conditions of 0.28 A for electrical current intensity, 1000.00 mg L-1 of aqueous extract of Moringa oleífera lam and 5 min for hydraulic retention time. While operating under optimal conditions, the removal of 71.38% of color and 5.22 mg L-1 of iron residual concentration was achieved.

Hydraulics characteristics of forward osmosis membrane module boundary based on FBG sensing technology: Hydraulic properties and operating condition optimization

To obtain more information on the hydraulic properties of membrane interface, the fiber Bragg grating (FBG) sensing technology was imported to investigate the effect of feed solution (FS) flow rate, draw solution (DS) flow rate and cross-flow direction on the membrane flux and membrane shear-force distribution of forward osmosis (FO) process. Results from experimental work demonstrated that a non-uniform spatial variation of the shear-force distribution exists along the membrane, and higher shear force is distributed in the middle position which resulted in higher diffusion load on the particular location of the membrane rind. Besides, increasing the inlet flow simply to a certain value didn't result in a higher shear force and lower the effect of concentration polarization (CP). Compared to co-current mode, counter-current mode showed the better hydraulic characteristics of higher shear-force, faster scouring frequency and consistent shear-force distribution, which will enhance the utilization of membrane and exhibit higher flux by increasing the inlet flow. Moreover, with the increase of FS and DS flow, the stress distribution showed more uniformed. Higher FS flow is more beneficial to FO process which will reduce ECP and improve flux in comparison to increasing DS flow which will produce adverse influence on ICP and diminish flux.

Simultaneous separation and degradation of surfactants laden in produced water using PVDF/TiO2 photocatalytic membrane

Massive volume of produced water laden with surfactants is generated from enhanced oil recovery (EOR) platform. Besides surfactants, this produced water also holds various organic and inorganic pollutants which requires intensive treatment before being discharged offshore. Current research focused on a radical solution for actual application in which the PVDF-TiO2 hollow fiber photocatalytic membranes were fabricated to simultaneously separate and degrade the surfactants laden in produced water. The characterization study portrayed the membranes with increasing TiO2 nanoparticles exhibited an improvement in surface hydrophilicity, porosity and tensile strength; besides, having an appropriate surface morphology and topology to remove the surfactants from produced water. Nevertheless, an excessive loading of TiO2 nanoparticles beyond 2 wt% had deteriorated the membrane performances in terms of flux and surfactant rejection measured as COD removal. These deteriorations were justified by the agglomeration of excessive TiO2 nanoparticles as observed occluding the pores on membrane surface. In predicting the membrane flux and rejection amidst the simultaneous separation and degradation of surfactants from produced water, two statistical models were subsequently derived by manipulating the produced water pH and air bubble flow rate (ABFR) of reactor operating conditions. The models permitted the fundamental comprehension of the correlations between the membrane flux and rejection parameters against the reactor operating conditions. Considering these correlations, the optimization of reactor operating conditions was finally evaluated and determined to achieve at the pH of 6.00 and ABFR of 0.41 L/min, giving rise to the membrane flux and rejection of 47.95 ± 1.34 L/m2h and 66.73 ± 0.76%, respectively.

Novel Formaldehyde-Free Electroless Copper for Plating on Next Generation Substrates

The deposition of electroless Copper on dielectric substrates and the subsequent electrolytic build-up of a thicker Copper layer are widely used steps within the production of modern Printed Circuit Boards (PCB), and while there have been numerous developments within PCB production, the current manufacturing technologies continue to be reliant on the autocatalytic deposition of Copper from a solution containing formaldehyde as the reducing agent, even though the chemistry is known to pose a risk to human health. Further, as the high volatility of formaldehyde generally increases the exposure to the hazard, it is understood that critical air concentrations can easily be exceeded. With this in mind it is clear that the development of environmental and user friendly electroless Copper baths has become a subject of importance. Nevertheless, the introduction of “green” plating chemistry into the market remains a challenge due to high industrial standards in terms of performance and cost-efficiency, which have been established by the conventional plating products and limit their replacement. In the case of the electroless Copper baths, formaldehyde-free alternatives have to show excellent substrate coverage with metal, provide coatings with high conductivity and uniformity and should lead to very good reliability results. Moreover, the solution, and final Copper layer have to function with the diverse range of dielectric materials that are currently employed. Due to application needs, there has been a shift within PCB design towards the use of very smooth substrate materials with low coefficients of thermal expansion. Such materials offer the opportunity for further miniaturization of circuits and are optimal for adoption within packaged die components (IC substrates). However, smooth substrate topographies typically lead to a limited adhesion of the electroless Copper layer, and increases the risk of delamination or blister formation. To prevent this, the properties of the metal film itself, as well as the chemical properties of the Copper bath, from which it is deposited, are critical, with a key factor being that the deposited layer is generated under internal tensile stress, as this has been shown to be of importance in reducing blister occurrence. While formaldehyde based plating solutions have been modified to satisfy this requirement through the adoption of additives and organic substances, there is still very little experience available regarding chemical approaches utilizing other reducing agents. Changing the reducing agent generally requires a complete redesign of the electroless system, including careful selection of the complexing agents and additives, readjustment of the chemical concentrations and optimization of the baths physical operating conditions. In this work we describe a new type of formaldehyde-free electroless Copper solution suitable for a broad set of applications and materials, and specifically the processing of next-generation substrates. This new plating solution has been successfully applied in both laboratory and production-scale environments, with its performance being evaluated and benchmarked against an existing formaldehyde-containing reference. The obtained metal layer has been characterized through a number of analytical techniques, including microscopy, XRF, SEM, adhesion tests as well as non-blister performance. Based on the data obtained we believe that the newly developed solution utilizing a non-formaldehyde reducing agent provides a suitable technology for PCB production without a loss of process performance, and thus provide a sustainable “green” alternative to the industry.

Performance Test and Operating Condition Optimization of Parallel Plate Plasma Reactor for Carbon Dioxide Decomposition

Performance Test and Operating Condition Optimization of Parallel Plate Plasma Reactor for Carbon Dioxide Decomposition

From rotating disk electrode to single cell: Exploration of PtNi/C octahedral nanocrystal as practical proton exchange membrane fuel cell cathode catalyst

PtNi/C octahedral nanocrystal catalyst is prepared through surfactant-assisted solvothermal approach using cetyltrimethylammonium bromide as structure directing agent, and its performance on rotating disk electrode and membrane electrode assembly are investigated through experiment and simulation. Its mass activity and specific activity at 0.9 V vs. RHE are about 6.1 and 6.6 times high of commercial Pt/C, respectively. The membrane electrode assembly that is fabricated using PtNi/C octahedral catalyst in cathode exhibits enhanced power generation performance and durability. Its cell voltage at 1000 mA cm−2 is increased by 34 mV compared with the control, and its maximum power densities are raised by 160.2 mW cm−2 and 0.27 kW gPt−1. After 100 h galvanostatic durability test, the attenuation rates of its cell voltage at 1000 mA cm−2 and maximum power density are 6.9% and 14.3% (10.9% and 18.4% for the control), respectively. The simulation results also reveal that PtNi/C octahedral catalyst not only has high half cell performance, but also shows actual application potential in single cell, which demonstrates the feasibility that the excellent performance of PtNi/C octahedral catalyst at rotating disk electrode level can be realized in single cells through optimization of membrane electrode assembly fabrication and cell operation conditions.

Optimization of Ni loading and operating conditions for carbon dioxide reforming of methane over NiO/CeO2 catalyst using response surface methodology

Optimization of Ni loading and operating conditions for carbon dioxide reforming of methane over NiO/CeO2 catalyst using response surface methodologyModelling and optimization of Carbon Dioxide Reforming of Methane (CORM) reaction over NiO/CeO2 catalyst were developed using Response Surface Methodology (RSM). Relationship between responses, i.e. CH, conversion, H2 and CO selectivities, and three independent variables, i.e. reactor temperature, CO2/CH4 ratio, and wt. % Ni in the CeO-supported catalyst, were presented as empirical mathematical models. The models showed a good fitting to the experimental data statistically. The NiO/CeO2 showed a potential catalyst for the CORM process, though some coking formations were found. The catalysts exhibited a promising catalytic performance with the unity H2/CO ratio in the product, high methane conversion, and low reverse water gas shift reaction. The reactor temperature, CO2/CH4 ratio, and wt. % Ni in the CeO2-supported catalyst being 840oC, 1, and 6.5%, respectively were suggested with respect to CH4 conversion, H2 and CO selectivity, and H2/CO ratio of 75.7%, 68.5%, 54.5%, and 1.03, respectively. Keywords: Carbon dioxide reforming of methane, NiO/CeO, catalyst, Response Surface Methodology AbstrakPermodelan dan optimisasi reaksi pembentukan kembali metana dengan karbondioksida (CORM) melalui katalis NiO/CeO2 telah dikembangkan dengan menggunakan Response Surface Methodology (RSM). Hubungan antara respon-respon (konversi CH, selektifitas H2 and CO) dengan tiga peubah tak bergantung (temperatur reaktor; rasio CO2/CH4, dan % berat Ni dalam katalis berpenyangga CeO) dinyatakan dalam model matematika empiris. Model empiris tersebut secara statistik menunjukkan korelasi yang baik terhadap data-data eksperimen. NiO/CeO2 tersebut menunjukkan sebuah katalis yang berpotensi untuk proses CORM. Katalis tersebut menunjukkan kinerja katalitik yang menjanjikan dengan rasio H2/CO mendekati satu dalam produk, konversi metana yang tinggi, dan reaksi reverse water gas shift yang rendah. Temperatur reactor 840oC, rasio CO2/CH4, 1, dan 6.5 wt. % Ni adalah direkomendasikan dengan konversi CH4 75.7%, selektifitas H2 68.5%, selektifitas CO 54.5%, dan rasio H2/CO 1.03. Kata Kunci: Pembentukan kembali metana dengan karbondioksida, Katalis NiO/CeO2, Response Surface Methodology

Optimization of operational conditions for a thermoelectric refrigerator and its performance analysis at optimum conditions

In this study, a portable mini thermoelectric refrigerator driven by a Peltier element is designed, constructed and tested. The Peltier element combined with fans on both sides is mounted onto a refrigerator box. An optimization for the operating conditions of the thermoelectric refrigerator is performed. The operating conditions of the system are the ambient temperature and voltages of the fans and Peltier element. Performance analysis for the optimum conditions obtained is presented. Results show that the optimum voltages of the Peltier element, inner and outer fans maximizing the cooling coefficient of performance of the system (COP) are 12 V, 3 V and 9 V, respectively. The optimum ambient temperature is 293 K. Results also show that the cooling COP of the system decreases from 0.351 to 0.011 while the temperature of the cooled space changes from 293 K to 254.8 K. The proposed thermoelectric refrigerator is used to keep drinks, foods or medicines fresh and cool.

Process performance optimization and mathematical modelling of a SBR-MBBR treatment at low oxygen concentration

Abstract In this study, performances of a SBR-MBBR in terms of COD, TN removal efficiency and sludge production were compared to that of an A/O-MBBR. The SBR-MBBR (40% filling ratio) at 24, 18 and 12 h HRT had a COD and TN removal efficiencies of 88 and 75%, 92 and 72%, 90 and 47%. Increasing the filling ratio to 60% with 12 h HRT, the COD and TN removal efficiencies raised to 93% and 66%, respectively. Thus, increasing the filling ratio of the MBBR the TN removal was improved. The A/O-MBBR configuration achieved a COD and TN removal efficiencies, respectively, of 85% and 72%. This configuration obtained the highest sludge yield due to an increase of the sludge production. Nitrification and denitrification activity tests, performed on attached and suspended biomass, revealed a specialization of the microbial community with the suspended biomass responsible for the denitrification process while the attached biomass for the nitrification. Moreover, a mathematical model consisting of a system of impulsive ordinary differential equations was developed to simulate the SBR-MBBR process. The mathematical model was successfully calibrated and validated through the collected experimental data, resulting in a suitable tool for process efficiency prediction and optimization of operational process conditions.

Operational Optimisation for Hybrid Membrane-Distillation Systems

Hybrid membrane-distillation systems are reported to be an energy-efficient separation processes compared to conventional distillation process; especially for separating close-boiling mixtures. However, several optimization methods are available and can be applied to find a cost-effective design and operation of hybrid membrane-distillation systems. This work evaluates the hybrid system design in terms of energy and compares the performance (i.e. the accuracy and computational efficiency) of stochastic optimisation method (Simulated Annealing) and deterministic method (Pattern search method) for optimisation of process operating conditions. The parallel hybrid membrane-distillation system for the separation of ethylene-ethane mixture is selected for analysis. The decision variables manipulated for the optimisation are the stage cut and permeate pressure. Results show that pattern search is faster than Simulated Annealing but that is more able to find the close-global results. The difference between the optimal result found by Simulated Annealing and pattern search is about 0.02 % for the total operating costs, 0.3 % for the stage cut and 5 % for the permeate pressure. These findings suggest that it is possible to use deterministic method for optimisation complex system. However, to locate an optimal solution and increase confidence in the result, a variety of initial points should be tested.

The simulation analysis and operation conditions optimization of low-head water bulb tubular turbine based on different guide vane outlet angle

The work of low-head water turbine mainly relies on the large flow rate, but the larger flow at different positions of the flow channel are easy to cause different hydraulic loss, and they may also have a poor stability. The paper based on a typical case of low-head water turbine unit over the Yellow River, according to the efficiency of the low-head water turbine and the hydraulic loss theory, and according to the real machine guide vane and the surface shape of turbine vane, and when a fixed vane turning, change the guide vane outlet angle and calculate the computing velocity and energy characteristics, then the unit was found with the high est efficiency between the 200 m3 / s - 250 m3 / s, and then we put forward the concept of conditions interval optimization from the angle of theory. Do corresponding numerical simulation on its working conditions and the real machine test under the same working condition, the test results consistent with theoretical calculation. In combination with theoretical calculation and the real machine test conclusion, and on the basis of the conclusion of low-head water turbine to make condition optimization and through the actual operation to achieve a certain effect, which provide a solution for the economical and safe operation of the low-head water turbine.

An effective approach for improving flotation recovery of molybdenite fines from a finely-disseminated molybdenum ore

An effective flotation approach is proposed for improving the recovery of molybdenite fines from a finely-disseminated molybdenum ore. To maximize the flotation recovery of molybdenum, process mineralogy of raw ore, contrast tests, optimization of operation conditions and particle size analysis were systematically investigated. Process mineralogy suggests that in the raw ore, 61.63% of molybdenite particles distribute in the <20 μm size fraction, and intergrow with muscovite and pyrite as the contained and disseminated type. Contrast tests indicate that conventional flotation responds to poor collection efficiency for particles less than 25 μm. Oil agglomerate flotation (OAF) process demonstrates an obvious superiority in improving the flotation recovery of molybdenite fines. Furthermore, the flotation results of OAF process reveal that the dosage of transformer oil plays a critical role on the average size of collected mineral particles (d 50 p ), agglomerates (d 50 a ) and the molybdenum recovery. In addition, industrial tests illustrate that compared with the Mo-S bulk flotation approach, OAF process not only increases Mo recovery and grade of molybdenum concentrate by 22.75% and 17.47% respectively, but also achieves a sulfur concentrate with a superior grade of 38.92%.

FLOW-INJECTION SPECTROMETRIC DETERMINATION OF SODIUM DICLOFENAC IN PHARMACEUTICAL FORMULATIONS

A flow-injection spectrometric method for determination of sodium diclofenac in pharmaceutical formulations was developed on this work. Sodium diclofenac solutions were injected into a stream of deionized water that reacted with potassium permanganate on acid medium producing Mn2+ ions whose exhibit maximum absorbance at 450 nm. The methodology used optimize experimental parameters was 33 factorial design and response surface. The proposed method obeyed the Beer’s Law over the range 25-160 mg L-1, applied in tablets and ampoules samples. Results were compare with the reference method. It was verified at the 95% confidence level, through paired t -test application – there is no statistic difference between them. The detection limit was valued in 2.6 mg L-1, relative standard deviation for 10 consecutive injections was 1.5% (100.0 mg L-1 sodium diclofenac solution) and the sample throughput was 80 samples h-1. Regarding optimization of operational conditions, the FIA spectrometric method presented analytical performance as good as other elaborated flow analyzers. Offers a simple and inexpensive way to this drug indirect determination aiming quality control on pharmaceutical industry’s assembly line. However, it can not be used for adulteration screening analysis due to non-selectivity and non-specificity of redox reactions.