SUZIMARA ROVANI
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Resumo IPEN-doc 27665 Effect of experimental variables on the extraction of nanosilica prepared by sugarcane bagasse ash2020 - FUNGARO, D.A.; CARVALHO, F.B.; ROVANI, S.; SANTOS, J.Sugarcane bagasse is one of the important biomass sources in Brazil, which is used as a fuel in the sugar industry. As a result, a large quantity of ash is generated and creates a serious disposal problem. The waste bagasse ash can be used as a valuable material to obtain nanosilica. Initially, NaOH was mixed with sugarcane bagasse ash (ash:NaOH 1:2 w/w) and the resultant mixture was fused at 350 °C for 30 min. Next, sodium silicate was solubilized in water and nanosilica was produced by neutralizing with acid. The structure, properties and yield of silica produced is strongly influenced by the extraction method used. Therefore, the silica extraction was conducted using various type of acid (hydrochloric, sulfuric and acetic), acid concentration (0.5; 4.0; and 8.0 mol L-1) and gelation pH (2, 4 and 7 for hydrochloric and sulfuric acids and 4, 5 and 7 for acetic acid). The synthesized nanosilica characteristics were studied using various techniques. Experimental results showed that hydrochloric acid and sulfuric acid produced nanosilica materials with similar yield and purity in each different process parameter. The production of nanosilica particles with the addition of acetic acid was the least favorable under the study conditions, probably due to its weak acid characteristic. The purity of all the synthesized silica nanoparticles is in the range of 94-98% and impurities such as sulfur and iron were presents as main minor compound. The study reveals that the industrial waste material sugarcane bagasse ash acts as an alternative source for the production of nanosilica powder widely used in areas such as ceramics, chemicals, catalysis, chromatography, energy, electronics, coatings, stabilisers, emulsifiers and biological sciences.Resumo IPEN-doc 26531 Comparative study of methods for the synthesis of silica nanoparticles from sugarcane waste ash2019 - ROVANI, SUZIMARA; FUNGARO, DENISE; CARVALHO, FELIPE; SANTOS, JONNATANAdding value to agro-industrial solid waste is a challenge for sustainable and green chemistry. Brazil is the worlds largest producer of sugarcane, producing about 633 million tons per year, and generates huge amounts of sugarcane waste ash (SWA) which is a rich source of silica. Therefore, the development of a process related to the use of this raw material rich in Si for the production of silica nanoparticles (SiNPs) is fundamental. SiNPs are presently applied in paints, biopolymers, catalysts, adsorbents, among others [1]. In this study, SiNPs were produced from SWA by different routes and yield and purity of products obtained were evaluated. The synthesis of SiNPs was carried out by the two-step method. First, NaOH was mixed with SWA, and the resultant mixture was fused at 350 C for 30 min or 1 h, varying the ash:NaOH ratio (1:1.5 or 1:2). After, was added distilled water in the funded solid and refluxed for 1 h to leave all the sodium silicate dissolved in the aqueous medium [2]. Then, HCl or H2SO4 6.0 mol L-1 was added, dropwise, until pH decrease to 2.0. The yield of SiNPs extraction was around 67 % for samples obtained with ash:NaOH ratio 1:1.5, 30 min or 1 h of muffle and HCl solution. So, fusion time was not significant for the yield of the synthesis. Subsequent experiments were conducted at 30 min, ash:NaOH (1:2) and HCl or H2SO4 (Table 1). The yield of silica nanoparticles extraction was 93 % and 67 % with HCl and H2SO4, respectively. The silica obtained with H2SO4 showed lower yield, but higher purity, when compared to the silica obtained with HCl. The yield of silica extraction was higher with ash:NaOH ratio 1:2 and with the HCl. However, the highest purity was obtained with H2SO4.Resumo IPEN-doc 25150 Adsorption of bisphenol-A in aqueous solution using silica nanoparticles obtained from sugarcane ash2018 - ROVANI, SUZIMARA; SANTOS, JONNATAN J.; CORIO, PAOLA; FUNGARO, DENISE A.Scientists around the world have searched minimize problems related to the incorrect disposal of solid wastes and water contamination. Brazil, for example, is the largest producer of sugarcane in the world, generates around 3-12 million of tons ash/year or more, and this waste can be transformed into valueadded material. In this study, we tried to solve two problems at the same time, manufacturing an adsorbent material and applies it in the remediation of contaminated water with bisphenol-A (BPA), an endocrine disrupting compounds, which alters plasma sex hormone levels in fishes [1]. The silica nanoparticles were synthetized through the addition of silicate obtained from sugarcane ash in the solution of water/butyl alcohol (1:1) with 2.5% wt. of hexadecyltrimethylammonium bromide under constant stirring. Then, 0.5 mol L-1 H2SO4 solution was added to suspension until pH 4. The nanosilica formed was washed with distilled water, filtered and dried. The silica nanoparticles and BPA adsorbed on silica were characterized by different techniques. The maximum BPA adsorption capacity obtained was 80 mg g-1. From TEM images (Fig. 1A-B) of the silica nanoparticles it is seen that all particles has less than 20 nm. Fig. 1C shows the infrared spectra of samples. The band at 1058 cm-1 is due to the Si–O–Si asymmetric stretching, the band at 965 cm-1 is due to Si-OH bending vibrational absorption, the bands at 799 and 446 cm-1 are due to the Si–O–Si symmetric stretching. The presence of other bands in the blue spectra are attributed of BPA adsorbed on silica nanoparticles, at 554 cm-1 is due to aromatic ring deformation vibration of di-substituted benzenes, at 834 cm-1 is assigned to C-H vibrations out of the plane and at 1512 cm-1 is due to aromatic C=C stretching vibration [2]. The results of characterization of the silica nanoparticles manufactured showed that the material presents potential to be employed as adsorbent for remediation of water contaminated with endocrine disrupting compounds.Resumo IPEN-doc 25008 Adsorption study of acid orange 8 dye using silica nanoparticles obtained from sugarcane ash2017 - ROVANI, SUZIMARA; SANTOS, JONNATAN J.; CORIO, PAOLA; FUNGARO, DENISE A.Developing of new adsorbents becomes a very important need, especially because of the increase of contaminants present in rivers, oceans and any other water body capable of became potable. Biosorbents has a special feature, because they can solve two problems at the same time, once they are prepared from a natural source, giving a utility for wasted materials, and bioremediate a water body, adsorbing contaminants on their surface. In this context, the properties of a biosorbent prepared from sugarcane ash by surfactant mediated synthesis has been studied to the adsorption of acid orange 8 dye, a model molecule, aiming future applications for removal of emerging contaminants of water. According to the results of adsorption kinetic (Fig. 1A), the acid orange 8 dye removal was higher than 89% and 95% in 4 h of contact time for an initial concentration of 200 and 150 mg L-1, respectively. FTIR-ATR analyses (Fig. 1B) indicated the presence of bands: at 799 and 446 cm-1 are due to symmetric stretching of siloxane groups, at 1058 cm-1 is due the Si–O–Si asymmetric stretching, at 2925 cm-1 and 2850 cm-1 are due to the bending of –CH3 and –CH2, respectively, for silica-CTAB sample and additionally, at 1031, 689 and 641 cm-1 are due sulfur groups (S=O), out-of-plane deformation of ring and aromatics groups, respectively, of acid orange 8 dye. In TGA analysis (Fig. 1C), the peak between 150 to 235 °C for silica-CTAB sample has been attributed to the unbound CTAB less stabilized bonding sites on the silica surface due to hydrophobic– hydrophobic interactions of interdigitated CTAB and the peak around 256 °C indicates a stronger bonding of the surfactant to the silica surface due to the electrostatic binding of the ammonium cation head group to the electronegative silica surface [1]. For the silica-CTAB + dye sample, the substitution of the interdigitated CTAB of a second layer by dye was observed by the disappearance of the DTG peak between 150 to 235 °C. The displacement the DTG peak of 256 for 300 °C and appearance of the DTG peak around 435 °C are related to the dye adsorption. These aspects demonstrate the potential of silica nanoparticles obtained from sugarcane ash as new biosorbent for removal of organic compounds, such as, dye from aqueous solution and can be used to alleviate environmental problems.Resumo IPEN-doc 25007 Surfactant mediated synthesis of silica nanoparticles using sugarcane ash waste as renewable source2017 - ROVANI, SUZIMARA; SANTOS, JONNATAN J.; CORIO, PAOLA; FUNGARO, DENISE A.Green silica from renewable source can be used in very different materials, since addictive for construction materials or polymers to traditional products as glass, silicone rubber as well as source for silicon. Brazil is the world’s largest producer of sugarcane and generates huge amounts of sugarcane ash waste (SAW) which is a rich source of silica. This work investigates a method to produce pure silica nanoparticles from SAW. Initially, sodium silicate was obtained from sugarcane ash waste adapting the methodology published by Alves, et al., 2017. Subsequently, sodium silicate was added to a mixture of water/butyl alcohol (1:1) with 2.5% wt. of hexadecyltrimethylammonium bromide under constant stirring at 60 °C. Then, 0.5 mol L-1 sulfuric acid solution was added slowly to suspension until pH 4 and the resulting gel was aged at 60 °C for 8 h. The aged nanosilica gel was washed with distilled water, filtered and oven dried at 120 °C. The silica nanoparticles were characterized by different techniques. In the Figure 1 can be observed energy dispersive spectra (EDS) and transmission electron microscopy (TEM) images of sugarcane ash waste (A and B) and of silica nanoparticles (C and D). EDS of SAW shows the presence of several different elements (being Si, Fe, Al, P, Cl and S more abundant) and only Si and O were observed after synthesis procedure (Cu signal comes from TEM grid). Transmission electron microscopy image of samples exhibit a drastic alterations of the material size ranging from several micrometers (Fig. 1C) to less than 20 nm (Fig. 1D). The results indicate that was possible to obtain pure silica in a nano- size from waste material to reduce disposal and pollution problems.Resumo IPEN-doc 23239 Sugarcane biomass ash as a renewable source of nanosilica2017 - ROVANI, SUZIMARA; SANTOS, JONNATAN J.; CORIO, PAOLA; FUNGARO, DENISE A.