Felipe Silva Semaan

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Felipe verified their affiliation via an institutional email.

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• PhD
• Professor (Associate) at Fluminense Federal University

Maleic anhydride (CAS: 108-31-6) is a very interesting molecule since it has both a C=C bond and an anhydride carboxyl in its structure, forming a strained and very reactive five-membered cycle. This reactivity allows it to be used as a raw material both in the laboratory and industry. Important industrial substances such as tetrahydrofuran, butyro...

Developing new sensors presenting low-cost, portability, and disposability features is of paramount in the electrochemical field. Thus, this work proposes the fabrication of lab-made composite electrodes using acrylonitrile butadiene styrene, graphite, and aluminum oxide. In this investigation, the amount of aluminum oxide (0 to 12.25 w/w) was care...

Monitoring nitrate in aquatic systems is of fundamental importance since its presence at high levels can result in adverse effects on human health. Thus, in this work, manufactured carbon black (CB)/polylactic acid (PLA)-based 3D-printed electrochemical sensors modified with electrodeposited silver particles (AgPs) for nitrate analysis in real wate...

Interactions between riboflavin (of known and reversible electrochemical behavior) and boric acid (electrochemically inactive) were explored to expand the applicability of voltammetric techniques allied to composite sensors aiming at minimum sample consumption. The electrochemical cell used in this research consists of three electrodes: a working e...

The 3D photoelectrochemical cell was developed with epoxy resin and a working composite electrode produced with a blend of 3D printer commercial conductive filament of polylactic acid biopolymer and carbon black (PLA/CB) mixed with silica/tungsten (VI) oxide (SiO 2 /WO 3 ) synthesized was used for the determination of imidacloprid in water samples....

A novel composite material based on acrylonitrile‐butadiene‐styrene (ABS) and carbon black (CB) was proposed here. Different ratios between CB and ABS (40 : 60–60 : 40 %, w/w) were studied to obtain a substrate with improved electrochemical properties. These materials were characterized by techniques such as cyclic voltammetry (CV), electrochemical...

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This work integrated a lab-made conductive graphite/polylactic acid (Grp/PLA, 40:60% w/w) filament into a 3D pen to print customized electrodes (cylindrical design). Thermogravimetric analysis validated the incorporation of graphite into the PLA matrix, while Raman spectroscopy and scanning electron microscopy images indicated a graphitic structure...

In this work, silver nanoparticles (AgNPs) obtained from photographic waste were synthesized and electrodeposited via cyclic voltammetry using epoxy-graphite composite as an electrochemical substrate. Both electrodes, unmodified (Epoxy/C) and modified (Epoxy/C/AgNPs), were characterized electrochemically by electrochemical impedance spectroscopy (E...

Brief overview regarding our third year of work

73) Titular(es): UNIVERSIDADE FEDERAL DO RIO DE JANEIRO-UFRJ; UNIVERSIDADE FEDERAL FLUMINENSE. (72) Inventor(es): ANA LUISA SILVA; GRASIELLI CORREA DE OLIVEIRA; RICARDO CUNHA MICHEL; EDUARDO ARIEL PONZIO; FELIPE SILVA SEMAAN. (57) Resumo: ELETRODOS COMPÓSITOS BASEADOS EM GRAFITE E POLÍMEROS TERMOPLÁSTICOS O presente invento refere-se em um de seus...

Saccharin is a synthetic artificial sweetener, widely used in several dietary products. In this work, a graphite and paraffin-based composite electrode (80% m/m in graphite) modified by electrodeposition of silver film was developed to quantify saccharin in samples of commercial sweeteners through cyclic voltammetry. The electrodeposition step cons...

This study presents the use of dry bean pods as a solid phase for fluorescein removal from water. The non-pretreated solid phase did not display any sorption properties for the chosen dye. However, interesting sorption properties were observed following a chemical derivative treatment with nitric acid. The study was carried out using both batch and...

The use of additive manufacturing or three-dimensional (3D) printing has revolutionized different fields of science. Among the well-known advantages of this new technology, its low cost, reproducibility, large-scale production, and freedom to manufacture custom-made devices can be highlighted. In electrochemistry, 3D printing has been widely used i...

Resumo Acidentes ambientais que envolvem o vazamento de combustíveis e seus derivados apresentam alta toxicidade ao meio em que é veiculado. Combustíveis possuem compostos orgânicos como benzeno, tolueno, etilbenzeno e xilenos (BTEX), sendo estes os principais agentes de contaminação de solos e recursos hídricos. Este trabalho teve como objetivo a...

This work presents the development and characterization of an electrochemical sensor of tin hexacyanoferrate (SnHCF), produced from the modification by drop casting of the boron-doped diamond electrode (BDD), and its subsequent evaluation in the determination of dopamine (DP) in a synthetic saliva sample. The sensors, BDD-SnHCF and unmodified BDD,...

This work exploits the applicability of a chemically reduced graphene oxide (CRGO) modification on the electrochemical response of a glassy carbon electrode (GCE) for the first-time sensitive determination of furosemide in natural waters. The batch injection analysis (BIA) is proposed as an analytical method, where CRGO-GCE is coupled to a BIA cell...

In this study we propose an in situ low-cost electrochemical treatment by cyclic voltammetry (CV) for graphene oxide (GO) synthesis on the surface of graphite/ABS composite electrodes. Higher efficiencies were achieved while CV treatments were carried out in alkaline (KOH) background electrolyte, applying an elevated number of successive cycles (10...

This work presents the development of a new electrochemical method for the indirect determination of atorvastatin (ATO) using Pb²⁺ as a probe at a potential value of -0.40 V. The square-wave voltammetric parameters such as the frequency (50 Hz), amplitude (100 mV) and step size (2 mV) were adjusted to obtain the most symmetrical and intense probe p...

The main objective of this work was to evaluate the presence of lead and cadmium in galvanized steel tubes by hot-dip used exclusively for drinking water supply. In this research, samples of galvanized tubes were removed from walls of residential buildings with 30 years of use. In the process of hot galvanizing, the manufacturing standards allow or...

An electrochemical gold nanoparticle sensor was developed for the detection of zinc, cadmium and lead ions, due to its electronic properties provided by the large surface/volume ratio and its easy surface modification. Linear ranges for Zn2+, Cd2+ and Pb2+ solutions were 0.469–3.051 µM, 3.968–68.970 µM and 7.937–137.900 µM, respectively. Sensitivit...

Aiming at the use of 3D printing as a tool in the design of electronic components and sensors, the present work has developed a preliminary evaluation of the influence of printing conditions on the electrochemical behavior of PLA and commercial carbon conductor-based composites. For this, characterization experiments were carried out by means of in...

Caffeine is widely present in food and drinks, such as teas and coffees, being also part of some currently commercialized medicines, but despite its enhancement on several functions of human body, its exceeding use can promote many health problems. In order to develop new fast approaches for the caffeine sensing, graphite-epoxy composite electrodes...

The present work describes the synthesis of iron oxide magnetic nanoparticles (IONP) and citrate-capped IONP (IONP-citrate), via conventional chemical routes and ultrasound-assisted approaches. IONP and IONP-citrate samples were characterized by x-ray diffraction (XRD), vibrational spectroscopy (FTIR), differential scanning calorimetry (DSC), scann...

This work presents the development and characterization of a new chemically modified electrode exploiting recordable Au-rewritable compact discs (AuCDs) as substrate for drop casting of a chemically-reduced graphene-oxide slurry focusing on simple and low-cost electrochemical sensors. Increase in electrochemical responses in cyclic voltammetric and...

In the present work, an approach is presented on the use of nanomaterials and devices for the Defense area, aiming to describe, in its more general scope, aspects related to the use of concepts, tools and approaches pertinent to nanotechnology, which influences several other technologies that drive the Defense area. In particular, the development o...

A handcrafted, low cost sustainable electrochemical sensor based on graphite/PLA was developed and proposed for the simultaneous quantification of Pb2+ and Cd2+ in bijou (metallic ores) on the basis of square-wave anodic stripping voltammetry (SWASV). The proposed electrode was characterized by different complementary strategies such as cyclic volt...

A lab-made affordable composite electrode based on acrylonitrile-butadiene-styrene (ABS) and graphite was developed and applied for the simultaneous determination of vitamins B2 (riboflavin, VB2) and B6 (pyridoxine, VB6) in pharmaceutical samples. Different ABS-graphite composite electrodes (AGCE) were prepared in proportions ranging from 40 to 80%...

Given the possibility of exposure to various metals by inappropriate use of some commercially available hygiene products, it becomes necessary to develop simpler and more cost-affordable procedures to quantify those analytes in different matrices, allowing a local quality control even for smaller producers and industries. In this context, electroan...

The combination of two low-cost classical procedures based on titrimetric techniques is presented for the determination of pyridoxine hydrochloride in pharmaceuticals samples. Initially some experiments were carried out aiming to determine both pKa1 and pKa2 values, being those compared to values of literature and theoretical procedures. Commercial...

Spectrofluorimetric determination of furosemide in pharmaceutical – a didactical approach, from theory to practice. The purpose of this paper is to present a complete possible application of simple strategies to teach basic concepts of molecular spectrofluorimetry. An ordinary anti-hypertensive drug was chosen in order to demonstrate many theoretic...

Undoubtedly, the interactions between matter and heat have changed both the world and humanity’s evolution. From the discovery of fire to our current reality, passing through all of scientific history, heat control has allowed to protect ourselves, process food, manipulate metals, change and sterilize materials, accelerate synthetic pathways or eve...

In this work we report a family of mixed-ligand copper(II) clusters obtained with different nuclearities: [Cu3(μ-OH)(μ-dppi)3(μ-hfac)3] (1), [Cu4(μ-dppi)4(Hdppi)2(hfac)4] (2), [Cu5(μ-O)2(μ-dppi)(μ-Hdppi)2(μ-hfac)3(hfac)2] (3) and [Cu6(μ-O)2(μ-dppi)2(μ-Hdppi)(μ-hfac)6] (4) complexes, where hfac = hexafluoroacetylacetonate, dppi = diphenylphosphinate...

Graphite/silicone composites (SGCE) in different ratios were prepared and characterized for different strategies, such as thermogravimetry (TG), Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). A electrochemical characterization of the different electrodes was performed by applying cyclic voltammetry; experiments covered a potential...

Quinones are important scaffolds that are present in a variety of natural products or synthetic bioactive molecules. Arylation is an important strategy for accomplishing structural modifications, leading to new potential candidates for use as drugs. In the present work, palladium-catalysed, ligandless and phosphine-free Suzuki coupling reactions be...

This study presents some results regarding the development and characterization of graphite-epoxy composites for use as working electrodes in electroanalysis. Such composites were preliminary assessed by TGA-DTA, AFM, XDR and cyclic voltammetry (CV), standing for a suitable stable and low cost material for electroanalytical purposes. The described...

In this work an overview regarding smart electrochromic windows as a promising technology capable of providing significant energy savings in buildings is presented. Electrochromic windows are devices able to control of light and acclimatization of indoor spaces. Therefore, these technologies allow energy savings with lighting and HVAC systems of th...

This paper reports a new procedure for V2O5 synthesis using the combination of two traditional methods, melt quenching and sonochemistry, called melt sonoquenching. The resulting nanomaterial was characterized by several methods in order to verify physical and chemical characteristics, and its possible use as electrochromic electrode material. Scan...

Sildenafil citrate and furosemide are two drugs very well-known and used. Sildenafil citrate is a drug widely used and effective in the current treatment of erectile dysfunction, but it is also efficient in the treatment of pulmonary hypertension. Furosemide is a drug class of loop diuretics, so classified by acting on the loop of Henle. It is ille...

Dos experimentos de Alessandro Volta, William Nicholson, Anthony Carlisle, dentre tantos outros no século XVIII até os dias atuais, a pesquisa em eletroquímica tem mostrado ser fundamental para o desenvolvimento da sociedade, estando presente em nossas vidas de forma mais frequente e intensa do que imaginamos. Basta olhar para o computador pessoal,...

Sulfide derivatives are sulfur compounds mostly found in oil and its presence may cause serious consequences to the pipe in the withdrawal of oil, as well as its refining. For these reasons, its determination and removal are highly relevant to the oil industry. In this work, a graphite-epoxy composite electrode modified by nickel film was developed...

This chapter aims to present main aspects of biomimetic sensors, their obtainment and analytical applications, briefly revisiting fundamentals of voltammetry. These fields have experienced an impressive growth in recent years; basic and applied researches on bioinspired chemically modified electrodes are opening, this way, a wide range of new speci...

Data from theoretical, thermal, and spectroscopic methods were compared in order to map a possible mechanism for the thermal decomposition of furosemide, a diuretic compound, in solid state. TG/DTG curves suggested a two-stage decomposition process. The first product of decomposition is water (m/z = 18), released due to a dimerization resulting in...

Different solid composites made by mechanical dispersions of graphite particles into heated paraffin (from 65 to 80% graphite, in mass) were prepared and assessed in order to optimize their use in electrochemical and electroanalytical procedures for bioanalysis. Besides these, composites were also evaluated by thermoanalytical techniques aiming to...

In order to use composite electrodes as modification platform for analytical purposes, carbon was used as solid and paraffin as liquid phase in the composite preparation. To the electrodes use, first the electroactive area was determined and then the modifications were done. To this purpose, Prussian blue, neutral red and metallic copper were used....

The present work presents a simple and didactic approach regarding some concepts involved in voltammetric techniques, starting from some basic principles of electrochemistry and advancing to the field of electroanalysis, passing through a discussion of mass transport phenomena, and culminating in a breakdown between different types of voltammetric...

A Eletroquímica pode ser brevemente definida como o setor de estudos da Química que se interessa por fenômenos que envolvem transferências eletrônicas por interfaces. Há um crescimento exponencial dos interessados por esta área, fazendo com que a mesma esteja em processo de constante reavaliação e crescimento. As pesquisas em Eletroquímica e Eletro...

Carbon is an element easily found in different polymorphic arrangements, existing in at least three main well-established forms (diamond, graphite and fullerenes), each of which can exist in a variety of materials with different electrochemical and mechanical properties; such characteristics lead to many advantages of carbon electrodes such as low...

Polyurethanes (PU's) are an important class of thermoplastic and thermoset polymers obtained by polycondensation reactions among different polyols, isocyanates and chain extenders, leading to a wide variety of polymers with many different properties and applications. Their mechanical, thermal and chemical properties can be guided by the reaction be...

The present study reports some aspects of ion-pair formation between pyridoxine and dodecyl sulphate under suitable conditions of pH, and its application with analytical purposes. Electrochemical behavior of the analite onto a graphite-polyurethane electrode was assessed by both cyclic and square-wave voltammetries under different conditions (pH fr...

A graphite-paraffin composite electrode has been used for the determination of ethambutol, an antituberculosis drug, in pharmaceutical samples by anodic oxidation. Voltammetric studies were used to characterise the electrochemical behaviour of the ethambutol in different pH solutions (3.0, 8.0 and 12.0). Quantification was carried out using amperom...

The determination of minoxidil (MX) with potassium permanganate as a carrier in a flow injection method is described. The detection at 550 nm was linear from 1.0 × 10-5 to 5.0 × 10-4 mol L-1. The limit of detection (3/slope) was 8.92 × 10-6 mol L-1, with an analytical frequency of 32 h-1. The proposed method was applied to commercial samples, with...

The combination of two low-cost classical procedures based on titrimetric techniques is presented for the determination of pyridoxine hydrochloride in pharmaceuticals samples. Initially some experiments were carried out aiming to determine both pKal and pKa2 values, being those compared to values of literature and theoretical procedures. Commercial...

The thermal properties of verapamil hydrochloride (VRP) and its physical association as binary mixtures with some common excipients were evaluated. Thermogravimetry (TG) was used to determine the thermal mass loss, as well as to study the kinetics of VRP thermal decomposition, using the Flynn-Wall-Ozawa model. Based on their frequent use in pharmac...

A solid graphite–polyurethane composite electrode has been used to determine release profiles of verapamil, a calcium-channel blocker. The electro-oxidation process was characterized by cyclic voltammetry and electrochemical impedance spectroscopy and showed no adsorption of analyte or oxidation products, unlike at other carbon-based electrodes. Qu...

A graphite-polyurethane composite electrode has been used for the determination of furosemide, a antihypertensive drug, in pharmaceutical samples by anodic oxidation. Cyclic voltammetry and electrochemical impedance spectroscopy were used to characterize the electrooxidation process at +1.0 V vs. SCE over a wide pH range, with the result that no ad...

Two fast flow injection procedures with fluorimetric detection based on the furosemide emission are presented. The first configuration used a phosphate buffer solution pH 3.00, 0.2 ionic strength (μ) solution flowing at 3.0 ml min as carrier, a 80 cm sample loop (400 µl total sample injection), and a 40 cm long reactor coil, which was kept at room...

A fast flow injection procedure with spectrophotometric detection based on the furosemide complexation with Fe(III) ions in ethanolic media is described. As carrier the flow single line system configuration used an ethanolic 10 mol L Fe(III) solution flowing at 1.0 mL min, a 50 cm sample loop (250 µL total sample injection), and a 50 cm long reacto...

A photometric flow titration based on the redox reaction between KMnO 4 and minoxidil isdescribed. The best titration results were observed at 3.20 x 10 -4 mol L -1 KMnO 4 and 1.00 x 10 -3 mol L -1minoxidil, using the minoxidil solutions as titrant. The flow rate was fixed at 17 mL min -1 and the titrantwas added to the system in aliquots of 500 μL...

A photometric flow titration based on the redox reaction between KMnO4 and minoxidil is described. The best titration results were observed at 3.20 x 10-4 mol L-1 KMnO4 and 1.00 x 10-3 mol L-1 minoxidil, using the minoxidil solutions as titrant. The flow rate was fixed at 17 mL min-1 and the titrant was added to the system in aliquots of 500 µL, th...

Furosemide is a loop diuretic widely used as an antihypertensive. Its analysis, in pharmaceutical formulations, is often required for quality control and to develop new formulations. The aim of this work is to describe the development of a fast chromatographic procedure to determine furosemide in tablets. Adequate sample masses were prepared by dis...

A flow injection spectrophotometric method based on furosemide reaction with potassium permanganate is described. A flow system using as carrier a 3.0 x 10 -4 mol/l potassium permanganate solution was developed. This system used a 50 cm sample loop and a 100 cm reactor, which was kept at 50°C. The permanganate flow rate was 2.2 ml min -1 . The anal...

This work presents alternatives for Fe and Co determination in pharmaceutical samples using flow analysis. The first procedure describes Fe extraction in mineral/vitamin complexes. The best conditions were reached when HNO3 concentration and volume, sample mass and shaking time were 1.0 mol l−1, 5 ml, 25 mg and 10 min. Three mineral/vitamin complex...