Renata Lopes

• Federal University of Viçosa

Herein, the development of a niobium-based metal–organic framework (Nb-MOF) designed to serve as a catalytic support for the production of hydrogen (H2) from sodium borohydride (NaBH4) is reported. The Nb-MOF was synthesized via a solvothermal method using niobium ammoniacal oxalate (AmOxaNb) as the metal source and 1,4-benzenedicarboxylic acid (BD...

The performance of nickel and platinum bimetallic nanoparticles (NPs) supported on potassium niobate (KNbO3) is evaluated in the catalytic hydrolysis of sodium borohydride (NaBH4) to generate hydrogen (H2). KNbO3 was synthesized via a hydrothermal route using Nb2O5 and KOH as precursors. X-ray diffraction (XRD) confirmed the crystalline orthorhombi...

Environmental transformations with catastrophic effects have been observed in the world. Among these, it can mention climate change due to greenhouse gases, mainly due to CO2. In this sense, heads of state around the world have committed themselves to new forms of energy that do not harm the planet. Among these, hydrogen has stood out, as it has an...

The present work proposes a spectrophotometric method for deltamethrin determination using silver nanoparticles (AgNPs). The AgNPs are spherical with a diameter of~11 nm and a negative surface charge with zeta potential ranging from −4.1 mV (pH 2) to −48 mV (pH 10). The AgNP colloidal system showed greater stability at higher pH values and for a mo...

An unprecedented electrochemical sensor based on low-cost films combining carbon black (CB) and green-synthesized silver nanoparticles (AgNPs) is proposed for the voltammetric determination of ciprofloxacin, an antibiotic widely used in the treatment of infectious diseases. AgNPs were biosynthesized by using an aqueous plant extract of Camellia sin...

Pb ²⁺ ions are highly toxic to living beings because they tend to bioaccumulate in the body. For this reason, the development of simpler, low‐cost, and easy‐to‐operate techniques that can detect and quantify low concentrations of metal ions would help to identify contaminating media and improve public health. This work proposes a Pb ²⁺ voltammetric...

This study explores the stabilization by niobic acid, of Pt, Ni, Pd, and Au nanoparticles (NPs) for the efficient microheterogeneous catalysis of NaBH4 hydrolysis for hydrogen production. Niobic acid is the most widely studied Nb2O5 polymorph, and it is employed here for the first time for this key reaction relevant to green energy. Structural insi...

The presence of environmental contaminants is a major problem today. In this context, it is necessary to develop new sustainable materials to be used to remediate these contaminants. In this work, the serpentinite rock was impregnated with cobalt, 5%, 10% and 20% and used as a support for the synthesis of carbon nanostructures by CVD (chemical vapo...

Climate change-related disasters have occurred worldwide due to the exhaustive use of fossil fuels. One promising fuel alternative is hydrogen (H2), which has a high energy potential (1.42 × 108 J Kg−1) and is considered the future fuel. However, its storage processes, such as gas compression or liquefaction are still unfeasible due to its low dens...

Leachate from a composting plant was characterized and applied as a biofertilizer in lettuce crops. Characteristics of untreated (UE) and anaerobically treated (TE) leachate samples were compared. The pH of TE (8.2) increased in relation to the UE (5.2) due to an increase in ammonia nitrogen in TE (1197 mg L-1) compared to UE (859 mg L-1). Anaerobi...

Electrolytic paste (EP) from used batteries was innovatively utilized as a support for Ni-Co nanoparticles (Ni-Co NPs) to catalyze hydrogen evolution from NaBH 4. The materials exhibited a porous and heterogeneous morphology, characterized by a ZnMn 2 O 4 interplanar distance of 0.34 nm, as confirmed by SAED analysis. Elemental analysis identified...

In this work, an iron/biochar composite was evaluated as a catalyst for 3,6-dichloro2-methoxybenzoic acid (dicamba) herbicide degradation by heterogeneous Fenton-like process. The biochar was produced from pyrolysis of coffee husks. After FeII adsorption by biochar, the material was submitted to chemical reduction, via borohydride, producing zero-v...

The increasing production of electronic waste and the rising demand for renewable energy are currently subjects of debate. Sustainable processes based on a circular economy are required. Then, electronic devices could be the main source for the synthesis of new materials. Thus, this work aimed to synthesize graphene oxide (GO) from graphite rod of...

Dicamba, renowned for its limited sorption capacity, presents a substantial risk of contaminating surface and groundwater if the disposal of spray tank effluent is not adequately controlled. In this work, a dicamba effluent underwent treatment through a Fenton-like process employing an iron/hydrochar (Hy-Fe) composite, synthesized via hydrothermal...

Essential oils (EO) have diverse applications, such as antibacterial and antifungal activity. However, they are susceptible to oxidation in the presence of air, light, and moisture. In addition, they are thermally unstable. In this sense, it is necessary to develop techniques to increase the lifespan of EO. In this work, EO was obtained from cloves...

As plantas do gênero Psidium (Myrtaceae) apresentam, dentre seus usos relevantes, atividades biológicas relacionadas aos seus compostos ativos, com destaque ao óleo essencial (OE) presente na folha. Os OEs extraídos das folhas de Psidium guajava, Psidium cattleyanum e Psidium gaudichaudianum possuem aplicações em larvas de Aedes aegypti, herbicida...

In the classical approach, students have to verify assumptions using, amongst others, a "pure solution" or "the common-ion effect" concerning the situation they are studying to solve ionic solubility equilibria calculations. Furthermore, the simultaneous equilibria are shown in a non-trivial way. We propose a new way to understand these equilibria...

Contributing to the development of sustainable electroanalytical chemistry, electrochemically reduced graphene oxide (ERGO) films obtained from residual graphite of discharged Zn-C batteries are proposed in this work. Graphite from the cathode of discarded Zn-C batteries was recovered and used in the synthesis of graphene oxide (GO) by the modified...

This work describes a green synthesis, the characterization, and biological evaluation of silver nanoparticles (AgNPs). The AgNPs suspension was synthesized using aqueous leaf extract of Eucalyptus grandis, which presented a characteristic band at 407 nm in the UV-Vis spectrum. The AgNPs presented a spherical shape and size of 9.7 ± 0.3 nm. The nan...

In this work, cellulose-based composite biofilms doped with silver nanoparticles (AgNPs) have been produced by eco-friendly process. The AgNPs were synthesized from Ilex paraguariensis with an average size of 45 nm, a characteristic plasmon band at 450 nm and zeta potential of -23 mV. The biofilm has been synthesized by casting method, using differ...

Biochar is a material of great ecological interest obtained from the carbonization of biomass. Its structure is composed of graphene-like aggregates, and it contains useful functional groups such as carboxyl. Using these groups, biochar functionalization with triazole groups that improve support characteristics has been achieved to anchor and stabi...

In this work, the hydrochar process optimization was carried out from Brewer’s spent grains (BSG) using wet pyrolysis (WP) with one-pot acid activation. The Doehlert Matrix was used as an experimental design to evaluate the influence of temperature (100, 125, 150, 175, and 200 °C) and residence time (4, 14, and 24 h), totaling nine experiments. The...

Inclusion complexes (ICs) of 2-hydroxypropyl-b-cyclodextrin with the essential oil (EO) from Seculo XXI cultivar of Psidium guajava were prepared using kneading (KN) and freeze-drying (FD) methods. The resulting ICs clusters have a nanometric size, with a diameter of approximately 80 and 40nm for KN and FD, respectively. Complexation efficiency was...

Catalytic supports from natural resources such as biochar are highly appealing for ecological and economic reasons. Here, biochar from pyrolysis of coffee husk, an agribusiness residue, was used as support in the design of a Pd–Fe3O4-based nanocatalyst applied as H2O2 sensor. The oxidation of o-phenylenediamine by H2O2 was favorably catalyzed at pH...

Biomass valorization is essential, particularly in emerging countries. Here, hydrochar from arabica coffee straw was functionalized with a triazole group (HD-TRz) for use as a support of palladium nanoparticles (PdNPs-HD-TRz) applied in the Ullmann coupling reaction for the first time. It provided remarkably excellent selectivities, conversions at...

In this work, graphene quantum dots (GQDs) were synthesized by hydrothermal carbonization (HTC) of brewer’s spent grains. Doehlert matrix design was used to evaluate the effects of temperature and residence time on the GQDs’ properties, including their photocatalytic activity, totaling 9 experiments. Methyl orange (MO) was used as a model molecule...

Zero-valent iron nanoparticles (EGnZVI) were synthesized using Eucalyptus grandis (EG) leaf extract as a reducing/stabilizing agent. The studied materials (EG leaves, extract and EGnZVI) were characterized using the XRD, FTIR, Raman spectroscopy, SEM, TEM/EDS techniques. The results indicate that several organic compounds, including phenolics, pres...

Photocatalysts were synthesized from anodic paste of alkaline batteries waste. After washing step, the material was calcined at different temperatures such as 600 °C (AB-600), 700 °C (AB-700) and 800 °C (AB-800). However, only the temperature of 600 °C produced a Zn/ZnO heterostructure. The Zn/ZnO heterostructure consisted by hexagonal wurtzite str...

In this work, the removal of methyl orange (MOR) and methylene blue (MBL) by composites based on iron supported on biochar was evaluated. The biochar was produced from pyrolysis of arabica coffee (Coffea arabica) husks, following Fe(II) adsorption. The adsorbed Fe(II) was submitted to chemical reduction, via borohydride, producing zero-valent iron...

In this work, an iron ore tailings sample (IOT), collected from a tailings dam in Minas Gerais, Brazil, was characterized. The IOT presented point of zero charge of ∼ 6, specific surface area of 4 m² g⁻¹, and was mainly composed of hematite and quartz. Subsequently, experiments were performed to evaluate the adsorption of an anionic dye, Direct Red...

In this work, Co-doped titanate nanotubes decorated with Cu2O/CuO nanoparticles heterostructures (TNTs-Co-Cu) were successfully synthesized by hydrothermal method followed by an impregnation method. The photocatalysts were characterized by TEM, XRD, Raman spectroscopy, XPS, N2 adsorption/desorption, DRS, and Photoluminescence. The results confirm t...

In this work, biochar and bio-oil were produced from the sewage sludge of cosmetics industry effluent treatment plant via pyrolysis under N2 atmosphere, at 500 and 600 °C and 30 and 60 minutes. The biochar presented micrometric particles with a porous structure, with a surface area between 203 and 231 m² g–1 and amorphous aspect containing crystall...

The transformation and use of the biomass are of fundamental energetic and ecological interest. The general objective of this review is to provide an overview of biochar (a major biomass product) as a support for nanocatalysts and other reagents, its mode of coordination and activation with nanoparticles and applications. This includes the physico-...

The biomass use is of considerable ecological and economical interest and here, biochar, a byproduct of biomass carbonization, is magnetized with Fe3O4 for its use as gold nanoparticle (NP) support towards catalysis of p-nitrophenol (4-NP) reduction. Biochar was synthesized from coffee straw biomass via pyrolysis, while magnetite functionalization...

Dendrimers have already been successfully used in nanoparticle (NP) catalysis for many years, particularly for Pd NP protection towards carbon-carbon coupling reactions. In this paper, assemblies between Pd nanoparticles and...

In this work, a method for food dyes determination in fibrous fruit pulps was developed. The analytes Tartrazine, Twilight Yellow FCF, Erythrosine, Orange G and Allura Red were analyzed by reverse phase chromatography with diode array (DAD) detection. The sample preparation consisted of a simple procedure, based on initial pH adjustment of the samp...

In this work, bimetallic nanoparticles of cobalt and copper (NPLIB) were synthetized from obsolete Li-ion batteries cellphones and applied for the first time in the Cr(VI) removal. NPLIB has approximately 50 and 40% of Co and Cu content, respectively. The material is composed of Cu0 and Co0 but also presents metal oxides on its surface. The nanopar...

In this work, iron-based nanomaterials (IONs-1 and IONs-2) were synthesized from zero-valent iron nanoparticles (IONs-0) and characterized. IONs-1 were synthesized from IONs-0 by hydrogen peroxide treatment, followed by calcination at 350 °C. IONs-2 were synthesized from IONs-0 by sequential treatment with hydrogen peroxide and sodium hydroxide, re...

In this work, alkaline and nickel-metal hydride spent batteries were used as precursors of metals for the synthesis of polymetallic materials. These materials were synthesized via chemical reduction. Materials produced from nickel-metal hydride spent batteries (PM-NiMH) have a nanometric size, whereas the alkaline spent batteries (PM-Alk) have a mi...

This study evaluated the immobilization of Fe/Ni nanoparticles (Fe/Ni-NPs) on silica, bentonite and chitosan beads (CBs). The material generated by supporting Fe/Ni-NPs on CBs (Fe/Ni-CB) presented more advantageous characteristics for application in fluidized bed reactors (FBRs) than the others, such as high mechanical resistance and chemical stabi...

Silver nanoparticles (AgNPs) stabilized with glutathione (GSH) were used as nanosensors for the determination of fluoroquinolones such as ciprofloxacin (CIP), norfloxacin (NOR) and enrofloxacin (ENRO) in aqueous systems. The AgNPs were stabilized with GSH (Ag-GSH NPs), whereas the decrease of the surface plasmon resonance (SPR) band at 400 nm and t...

In this work biochars were synthetized from arabica coffee husks and were used for Fe (II) adsorption by a pyrolysis process at 350 and 600 °C. The in natura material before and after pyrolysis exhibited amorphous structure, showing levels of C, H, and N, for both biochars, around 70; 0.25; and 2.5% (m/m), respectively. The Point of Zero Charge (PZ...

Iron nanoparticles (nZVI) stand out in environmental remediation due to their high reactivity. However, they have low chemical stability when exposed to oxygen and water, reducing their effectiveness. The objective of this work was to develop and validate a method to evaluate the efficiency of nZVI from synthetic lots L01 and L02, from the degradat...

In this study, the copper nanoparticles (Cu NPs) reactivity for degradation of the reactive dye black 5 (RP5), picric acid (PA) and 2,4-D herbicide was evaluated. The RP5 degradation occurred by oxidative via, through hydroxyl radicals generated in situ, with active participation of Cu(I) and H2O2. The use of catalase confirmed the hydrogen peroxid...

In this work, magnetic cobalt nanoparticles (CoNPs) were synthesized and applied to the removal of Remazol golden yellow RNL (RGY) from aqueous solutions and textile wastewater. The CoNPs were characterized and the Co content found in the CoNPs was 60.38% (m/m). The analysis of X-ray Diffraction (XRD) and Raman Spectroscopy indicated the presence o...

Recent studies have shown Cu(0) as a promising material for the removal of organic and inorganic pollutants. However, there is no review addressing the studies performed. This fact may be related to the toxicity of the particles and the copper released in solution that has not motivated researchers, which entails in a reduced number of publications...

The cobalt nanoparticles (NPs-Co) were synthesized and applied in the removal of Cr(VI). The obtained nanomaterials presented magnetic properties and were characterized by the techniques of Transmission Electron Microscopy and X-ray diffraction. The NPs-Co, with a diameter of less than 50 nm, had a composition based on metallic cobalt and cobalt ox...

We showed some inconsistencies in the teaching of Chemistry of Solution in universities by proposing that historical development of research of Chemistry of Solutions occurred with the formation of two distinct concepts, the XIX century concept, and the XX century concept. XIX century concept was created before the Arrhenius' electrolytic theory an...

Kinetic studies of sulfentrazone herbicide dechlorination by Fe/Ni nanoparticles were performed in the presence of different electrolytes such as: Cl-, SO42-, NO3-, Cu2+, Na+ and Zn2+. In the presence of Cl- and SO42- the reaction occurred efficiently, reaching approximately 100% of dechlorination after 30 minutes of reaction. In the presence of NO...

The application of desiccant herbicides in the bean crop is fundamental in the production of quality seeds, since it anticipates the harvesting season, which makes it possible to obtain seeds in the period of physiological maturation, when they are reported with maximum accumulation of dry matter, high vigor levels and germination percentage. Howev...

The damage caused to the environment by the textile industry, creates a demand for simple and inexpensive methods that remove waste water dyes. In this sense, this work had as objective to evaluate and optimize the adsorptive capacity of the chitosan microspheres, of the direct red azo dye 80. The materials were characterized by SEM and FTIR techni...

In this study, direct black dye removal was investigated using iron nanoparticles (Fe NPs), copper (Cu NPs), and Fe/Cu (Fe/Cu NPs). NPs were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD). Using a dose of 0.25 g L⁻¹ of Fe, Cu, and Fe/Cu NPs, a degradation efficiency of 13, 26, and 43% respectively was obtained....

In this study, ciprofloxacin (CIP) degradation by zero-valent copper nanoparticles (nZVC) was investigated. The nZVC were characterized by transmission electron microscopy (TEM), X-ray spectroscopy by dispersion in energy (EDS) and X-ray diffraction (XRD). Approximately 100% of degradation was obtained at CIP concentration of 20 mg L⁻¹, pH 3.5 and...

The removal of the beta-lactam antibiotics (ceftriaxone and cefadroxil) through zero-valent copper nanoparticle (nZVC) was studied in this work. Excellent removal degrees (> 85%) were obtained for both analytes in only 20 min of reaction. Studies were performed in both oxic and anoxic conditions, and in the presence of t-butyl alcohol (TBA), an inh...

In this work, polymetallic nanoparticles were synthesized from printed circuit boards waste (PN-PCBs) through chemical reduction. The Transmission Electron Microscopy analyzes proved that the PN-PCBs have a spherical morphology with a diameter of approximately 30 nm. The energy-dispersive X-ray spectroscopy showed that the PN-PCBs consist mainly of...

This work presents the determination of amoxicillin (H3Amox+) in capsules by potentiometric titration. An optimized method was done with a standard amoxicillin solution that was title with NaOH solution. The initial pH was 4.35. As expected, the first equivalence point was not observed, because the fraction of H3Amox+ was about 2.4%. Thus, HCl solu...

The Fundão dam collapsed releasing 60 million tons of mining waste into the environment. The mining wastes should be better studied, since some of them are deposited on the alluvial plains soil and at the bottom of the rivers, like sediments, of the region affected. Thus, this work aims to perform the chemical, physical and adsorptive characterizat...

In this work, ozone oxidation of the antibiotics amoxicillin (AMX), cephalexin, and ceftriaxone was investigated in different samples: (i) aqueous solutions (100 mg L⁻¹), (ii) an industrial wastewater containing AMX at 125 mg L⁻¹ (chemical oxygen demand 6000 mg O2 L⁻¹), and (iii) a heavily contaminated industrial wastewater containing the antibioti...

In this work, the complexation of the hazardous β-lactamic antibiotic amoxicillin (AMX) with Fe3+ ions during coagulation was investigated. New bands in the ultraviolet-visible (UV-vis) spectra suggested that AMX molecules bind to Feaq3+ and also displace ligands from a stable Fe thiocyanate complex. Electrospray ionization mass spectrometry (ESI-M...

The degradation of the Reactive Blue 4 (RB4) dye by zero-valent copper nanoparticles (nZVC) was investigated. Degradation rates of approximately 90% were reached within 10 minutes of reaction. Total Organic Carbon (TOC) analysis shows that the dye molecules undergo mineralization, therefore indicating the degradation process is oxidative. Experimen...

A análise de imagens digitais é um método analítico baseado na decomposição da imagem, cujos os valores RGB variam proporcionalmente com a concentração do analito. Para a determinação de etanol, empregou-se a reação de óxido-redução na qual o cromo (VI) é reduzido a cromo (III) ou cromo (II), sendo o etanol oxidado a aldeído acético, gerando mudanç...

In this work the development and validation of analytical methodology for determination of copper in sugarcane spirit samples is carried out. The digital image based (DIB) method was applied along with spot test from the colorimetric reaction employing the RGB color model. For the determination of copper concentration, it was used the cuprizone - a...

This study evaluates aerobic and anaerobic biodegradability and toxicity of a real pharmaceutical wastewater, which focuses on antibiotics production. Zahn-Wellens and Organization for Economic Cooperation and Development (OECD) methodologies were applied in order to verify the wastewater's biodegradability and Microtox® analysis was performed for...

This work investigates the effect of different variables on acetamiprid degradation in aqueous systems by Fe/Ni nanoparticles. The variables studied were pH (2.0 to 5.0), temperature (283 to 313 K), and nanoparticles dosage (0.200 the 0.500 g.L-1). The reactions monitoring was made by HPLC. The degradation was greater than 90% in only 5 reaction mi...

This study investigated the reductive degradation of acetamiprid (5 mg L-1) in aqueous medium (at pH 2.0) induced by zero-valent iron (50 mg). The process was monitored using high-performance liquid chromatography (HPLC) to determine the degradation rate as a function of reaction time, and direct infusion electrospray ionization mass spectrometry (...

A multiclass method has been optimized and validated for the simultaneous determination of 113 pesticides residues belonging to several classes in peanuts. It has been based on QuEChERS methodology (quick, easy, cheap, effective, rugged and safe) and ultra high performance liquid chromatography coupled to triple quadrupole tandem mass spectrometry...

Antibiotics are considered emerging environmental issues and the presence of its traces in the environment can induce the development of resistant pathogens and promote allergies. Biological treatment is the most widely used method for industrial wastewater treatment, but it has been proved inefficient for the removal of all hazardous constituents...

This paper describes the optimization of a multiresidue chromatographic analysis for the identification and quantification of 20 pesticides in bovine milk, including three carbamates, a carbamate oxime, six organophosphates, two strobilurins, a pyrethroid, an oxazolidinedione, an aryloxyphenoxypropionate acid/ester, a neonicotinoid, a dicarboximide,...

An efficient analytical method for the simultaneous quantification of 27 veterinary drugs from five different classes (benzimidazoles, betalactams, quinolones, sulfonamides and tetracyclines) in bovine milk using a novel extraction procedure (liquid-liquid extraction with fast partition at very low temperature) and liquid chromatography coupled to...

A multiresidue method for the quantification of 128 pesticides in banana is described. It involves the application of a modified QuEChERS procedure followed by UHPLC–MS/MS (Ultra High Performance Liquid Chromatography coupled to Tandem Mass Spectrometry) analysis. The method was validated according to the European Union SANCO/12495/2011 guidelines...

A multiresidue method for the quantification of 13 sulfonamides in animal feed is described. It involves the application of a modified QuEChERS procedure followed by HPLC–MS/MS (high performance liquid chromatography coupled to tandem mass spectrometry) analysis. The best conditions for the extraction solution and PSA (primary secondary amine) mass...

A simple, selective and fast multiresidue method was developed for the determination of 32 veterinary drug residues belonging to several families, in gilthead sea bream (Sparus aurata) by ultra high performance liquid chromatography coupled to tandem mass spectrometry (UHPLC-MS/MS). The extraction was based on modified QuEChERS (quick, easy, cheap,...

A multiclass method has been optimized and validated for the simultaneous determination of 20 veterinary drug residues belonging to several classes, as quinolones, sulfonamides, macrolides, anthelmintics, avermectins and diamino derivatives, and benzathine, used as a marker of the presence of penicillin, in muscle chicken. It has been based on QuEC...