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The work aims to synthesize and characterize vegetal charcoal (or biochar) from Syzygium cumini (AC-SC), evaluating the adsorption capacity for dexamethasone drug (DEX) removal, using the kinetic and equilibrium adsorption. The samples were characterized by N

The present work aims to evaluate the removal capacity of Rhodamine B dye (RhB) using nano-porous chitosan (NC) from shrimp shells. NC was characterized by XRD, SEM-EDS, N

Antimicrobial resistance represents a serious concern to public health, being responsible for hospital infections, affecting mainly immunosuppressed patients. Thus, nanotechnology appears as an alternative to solve this problem, through the application of metallic nanoparticles with antimicrobial activity. The present work aims to synthesize and characterize AgNPs from Klebsiella pneumoniae (AgNPs-KP) and Aloe vera extract (AgNPs-AV), evaluating the antimicrobial activity against Klebsiella pneumoniae carbapenemase (KpC) and the cytotoxicity in the L929 cell line. AgNPs were prepared by the biosynthetic method using Klebsiella pneumoniae and were characterized by XRD, FTIR and SEM–EDS. Antimicrobial activity was tested using the MIC and MBC. The cytotoxicity was evaluated by the MTT method and neutral red. The production of ROS and nitrogen RNS tests were performed in the L929 cell line. Thus, it was possible to confirm the production of AgNPs-KP, through morphological, structural and elemental analysis. AgNPs from Klebsiella pneumoniae had potent antimicrobial activity in low concentration against antimicrobial resistant pathogens with MIC 9.76 µg mL−1 and MBC 9.06 µg mL−1. Moreover, AgNPs-KP in concentrations of 10, 30 and 100 µg mL−1 did not show cytotoxic properties for the L929 fibroblast, where only the cytotoxic effect was observed in high concentrations (300 µg mL−1). AgNPs-KP did not produce ROS about the analyzed concentrations and RNS production was only in the highest concentration of 3000 µg mL−1. Therefore, AgNPs biosynthesized by Klebsiella pneumoniae have potential medical applicability as a promising antimicrobial agent, using a simple and low-cost method, correlating nanomedicine as nanostructured materials.

Silver nanoparticles (AgNPs) were synthesized via three routes where silver was reduced by either citric acid (R1), glucose (R2) or glycerol (R3), and were stabilized with (3-aminopropyl) triethoxysilane (APTES). All nanoparticles were encapsulated in silica by the sol-gel process (SiAgE). Structural, textural, morphological and antibacterial properties of SiAgE were determined by: SEM, TGA, XRD, UV–VIS, FT-IR, BET, SAXS and disc diffusion. These SiAgE had antimicrobial properties, and they were used in ethylene polymerization using the Cp2ZrCl2/MAO catalytic system. The catalytic activities were high, and the percentages by weight of the fillers ranged from 1.1 to 1.6 wt%. The antibacterial properties of the nanocomposite films were studied by two tests: disc diffusion and the Parallel Streak method. The polyethylene (PE)/SiAgE nanocomposites inhibited the proliferation of Staphylococcus aureus (Gram positive) and Escherichia coli (Gram negative) bacteria in contact with the films, thus showing potential to be used as active packages in medicine.

The industrial effluent contaminated with organic pollutants has been causing an increase in the toxicity of the ecosystem, causing a great environmental impact. Thus, the present work aims the green synthesis of silver nanoparticles (AgNPs) from Aloe vera, its characterization and antimicrobial activity against Pseudomonas aeruginosa (ATCC 27853) and Staphylococcus aureus (ATCC 25923). AgNPs were characterized by X-ray diffraction (XRD), Scanning Electronic Microscopy with Energy Dispersive Spectroscopy (SEM-EDS), Zeta Potential (ZP) and N2 porosimetry (BET/BJH method). Antimicrobial activity were carried out by Minimal Inhibitory Concentration (MIC) method. The XRD demonstrated characteristic peaks of AgNPs at 38.29°; 44.55° and 64.81°, and SEM-EDS micrographs showed that AgNPs produced by biomolecules of Aloe vera extract resulted in a weight concentration around 92.59% silver, 7.15% oxygen and 0.26% chlorine. Regarding zeta potential, all samples showed negative electric charge (around −35.3 mV), while N2 porosimetry resulted in a surface specific area of 6.09 m2 g−1, with a volume and diameter pore of 0.032 cm³ g−1 and 33.47, respectively. Antimicrobial activity was observed at 15.62 µg mL−1 and 31.25 µg mL−1 for P. aeruginosa and S. aureus, respectively. Thus, AgNPs can be considered a promising nanoparticle for degradation of organic pollutants in aqueous solution as well as an adjuvant for treatment of microbial infections.

The pollution of wastewater with dyes has become a serious environmental problem around the world. In this context, the work aims to synthesize and characterize a supported nanocatalyst (NZ-180) from rice husk (RH) and alum sludge (AS) incorporating silver (AgNPs@NZ-180) and titanium nanoparticles (TiNPs@NZ-180) for Rhodamine B (RhB) dye degradation, under UV and visible irradiation. Central rotatable composite design (CRCD) was used to determine ideal conditions, using nanocatalyst and dye concentration such as input variables and degradation percentage like response variable. Samples were characterized by XRD, SEM-EDS, N2 porosimetry, DLS, and zeta potential analyses. TiNPs@NZ-180 showed the best photocatalytic activity (62.62 and 50.82% under UV and visible irradiation, respectively). Specific surface area has increased from 35.90 to 418.90 m2 g−1 for NZ-180 and TiNPs@NZ-180, respectively. Photocatalytic performance of TiNPs@NZ-180 has reduced to 8 and 10% after 5 cycles under UV and visible light irradiation. Ideal conditions found by CRCD were 2.75 g L−1 and 20 mg L−1 for nanocatalyst and RhB concentrations, respectively. Therefore, (agro)industrial waste present such an alternative material for application in the removal of wastewater with dyes, which helps in the reduction of the impact of chemicals/pollutants on human and animal health.

The disposal of solid waste containing toxic metals in the composition is a problem of environmental and human contamination. The amount of waste as printed circuit boards has been increasing year by year. New processes that aim at recycling and subsequent application implementing a circular economy of this waste have been gaining importance. This study proposes the printed circuit boards characterization for the copper recycling by acid leaching in two steps, green synthesis of copper nanoparticles using ascorbic acid (vitamin C), and later application of nanoparticles into surfactant degradation through the Fenton-like process. Acid leaching proved a possible methodology for recycling copper, obtaining over 90% recovery. The printed circuit boards show to be a copper secondary source with a weight percentage of about 26 and recovery of 97% in two leaching stages. The synthesis of CuNPs was inferred through UV–Vis with absorption peak in 585 nm and modification of the coloration over time of solutions to dark brown. The syntheses were performed at 70 °C, 80 °C, and 90 °C and in 0.17, 0.5, 0.83, 1, 2, and 3 h, and the stability of copper nanoparticles was verified in 168, 720, and 960 h after syntheses. Stable nanoparticles were produced with different diameters, and they were applied as a catalyst in the Fenton reaction to degrade an amine-based surfactant used in the mining industry. The total carbon degradation found was 57%. It was possible to observe that the recycling of printed circuit boards is strategic to obtain copper from a secondary source, and the synthesis of copper nanoparticles could be used as a product to applicate in the circular economy using the Fenton process.

Nanostructured zinc oxide (ZnO) prepared by combustion in solution was used to obtain nanocomposites. The ZnO particles were characterized by Brunauer-Emmett-Teller (BET), X-ray diffraction (XRD), and scanning electron microscopy (SEM), showing crystallite size of 32 nm and a superficial area of 32.6 m2 g-1. Nanocomposites with 1, 3, and 5 wt.% of ZnO in the polymeric matrix were obtained using the in situ polymerization of ethylene with catalytic activities between 1500-1700 kg (molZr h PE)-1. The high-density polyethylene nanocomposites (PEZnO) were characterized by thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), SEM, and transmission electron microscopy (TEM). The nanocomposites with 1 wt.% ZnO gave excellent mechanical properties, and all were active against Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria.

The use of graphite and polyolefins as starting materials to prepare nanocomposites is convenient because both are inexpensive and have very different properties, one is conductive and the other is insulating. The formation of nanocomposites can extend the applicability of both commodities. In this work we synthesized nanocomposites of polyethylene (PE) with two types of graphites, graphite oxide (GO) and reduced graphite oxide (RGO), by in situ polymerization using a supported metallocene catalyst. The functional groups on the graphites were used to support the metallocene catalyst by a previous treatment with methylaluminoxane. The nanocomposites were obtained with good catalytic activities and presented excellent morphology and dispersion; their elastic modulus and crystallization temperatures were higher than those of neat PE. However, the nanocomposites PEGO were insulant, whereas PERGO had a conductivity of 1.1 × 10 −5 S cm −1 with 3.1 wt% filler. This is a significant result compared to the conductivity obtained using non-supported graphite nanosheets where more than 15 wt% of graphite nanosheets are needed to obtain conductivities higher than 10 −7 S cm −1 . This improvement in the percolation threshold was attributed to the good morphology of the PERGO nanocomposites obtained due to the control of the graphitic sheets and the support methodology.

This work aimed to produce graphene oxide with few graphene layers, a low number of defects, good conductivity and reasonable amount of oxygen, adequate for use as filler in polymeric composites. Two starting materials were evaluated: expanded graphite and graphite flakes. The method of oxidation used was the Staudenmaier one, which was tested over different lengths of time. No appreciable differences were found among the oxidation times and so the lowest oxidation time (24 h) was chosen as the most adequate. An investigation was also conducted into suitable temperatures for the reduction of graphite oxide. A temperature of 1000 ºC gave the best results, allowing a good quality material with few defects to be obtained. The reduction was also evaluated under inert and normal atmosphere. The best results were obtained when the least modified material, e. g., graphite flakes, was used as a starting material, oxidized for 24h and reduced at 1000 ºC for 30 s in a quartz ampoule under a normal atmosphere.

As placas de circuito impresso (PCIs), principal componente dos equipamentos eletroeletrônicos (EEEs), apresentam composição variada. No geral, elas são constituídas por materiais cerâmicos, poliméricos e elementos metálicos, sendo que alguns deles possuem valor econômico, como, por exemplo, cobre, prata, ouro, níquel e paládio. Por outro lado,existem elementos que são prejudiciais ao meio ambiente e à saúde, como chumbo, mercúrio e cádmio. Em relação à prata, além de possuir um alto valor econômico também pode ser reinserida na cadeia produtiva na forma de outros produtos, como por exemplo, nanopartículas. A prata presente nas PCIs pode ser recuperada através da combinação de processamento físico e hidrometalúrgico. Nesse trabalho foi estudada a composição de PCIs provenientes de celulares obsoletos por meio de processamento físico (cominuição e separação magnética) e caracterização química (ICP-OES). A fração magnética, a qual apresentou maior teor de prata, correspondente a 0,23% das PCIs, foi utilizada para o processamento hidrometalúrgico em duas etapas, sendo a primeira a lixiviação em meio ácido sulfúrico (H2SO4) e uma segunda lixiviação em ácido sulfúrico em meio oxidante (H2O2). Após a lixiviação, a prata foi recuperada na forma de AgCl através do processo de precipitação seletiva, sendo avaliado o uso de dois agentes precipitantes o cloreto de sódio, NaCl e ácido clorídrico, HCl. O sólido obtido após a etapa de purificação pode ser usado como precursor na síntese de nanopartículas de prata (AgNPs) as quais apresentam potencial de aplicação em diversos setores da indústria. Para a síntese de AgNPs foram utilizados a glicose como agente redutor e dois agentes estabilizantes: o citrato de sódio e a polivinilpirrolidona (PVP). As AgNPs foram caracterizadas através das seguintes técnicas instrumentais: espectrofotometria na região do UV-vis, difratometria de raiosX (DRX), espalhamento de luz dinâmico (DSL), microscopia hiperespectral de campo escuro (MHCE) e microscopia eletrônica de varredura com emissão por campo (MEV/FEG). Na síntese de AgNPs utilizando o citrato de sódio como agente estabilizante, os melhores resultados foram obtidos a partir da relação molar de 1:2 para Ag:Glicose e da relação molar de 1:5 para Ag:Citrato de sódio, adotando uma temperatura de 60 °C, resultando em AgNPs com duas faixas de diâmetros de 47 e 2 nm. A síntese de AgNPs utilizando o PVP como agente estabilizante, as melhores condições foram obtidas utilizando uma relação molar Ag:Glicose de 1:2, sob temperatura de 60 °C e uma relação mássica Ag:PVP de 1:4,45, sendo formadas AgNPs com duas faixas de diâmetros de 65 e 5 nm. As propriedades ópticas e morfológicas indicaram AgNPs polidispersas predominantemente com formato esférico. As propriedades antibacterianas das AgNPs foram avaliadas frente a bactéria E. coli., e os resultados sugerem que AgNPs são fortes agentes inibidores para bactérias Gram-negativas Printed circuit boards (PCBs) are the main component in practically all electronic equipment (EEE), and have a varied composition, but, in general, it consists of ceramic, polymeric materials and metallic elements, where some of them have a high economic value, such as copper, silver, gold, nickel and palladium, as well as elements that are harmful to the environment and health, such as lead, mercury and cadmium. Regarding silver, in addition to having a high economic value, it can also be reinserted into the production chain in the form of another product such as nanoparticles. Silver is present in the PCBs and can be recovered through the combination of physical and hydrometallurgical processing. In this work, the composition of PCBs from obsolete smartphones was studied through physical processing (comminution and magnetic separation) and chemical characterization (ICP-OES). The magnetic fraction, which had the highest silver content, corresponding to 0.23% of the PCBs, was recovery from hydrometallurgical processing, which involved two stages, the first leaching in sulfuric acid medium and second leaching in sulfuric acid in oxidizing medium (addition of hydrogen peroxide - H2O2). After the leaching, the silver was recovered as AgCl through a selective precipitation process applying to precipitating agents sodium chloride, NaCl and hydrochloric acid, HCl. The solid obtained after the purification stage can be used as a precursor in the synthesis of silver nanoparticles (AgNPs) which have potential for application in several sectors of the industry. In the AgNPs synthesis, with glucose as reducing agent and was used two stabilizers: sodium citrate and polyvinylpyrrolidone (PVP). AgNPs were characterized by the following instrumental techniques: UV-vis spectrophotometric, X-ray diffraction (XRD), dynamic light scattering (DLS), dark field hyperspectral microscopy (DFHM) and Field Emission Gun Scanning Electron Microscopy (SEM/FEG). Synthesis of AgNPs using sodium citrate as stabilizing agent, the best results were obtained from the molar ratio of 1:2 for Ag:Glucose and the molar ratio of 1:5 for Ag: Sodium citrate, temperature of 60 °C, resulting in AgNPs with two diameter ranges of 47 and 2 nm. In the synthesis of AgNPs using PVP as stabilizing agent, the best conditions were obtained using a molar ratio Ag:Glucose of 1:2, under a temperature of 60 °C and a mass ratio Ag:PVP of 1: 4,45, AgNPs are formed with two diameters of 65 and 5 nm. The optical and morphological properties indicated polydispersed AgNPs predominantly spherical in shape. The antibacterial properties of AgNPs were evaluated against E. coli. bacteria, and the results suggest that AgNPs are strong inhibitory agents for Gram-negative bacteria.