SUZIMARA ROVANI

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    Artigo IPEN-doc 30211
    Physico-chemical characterization of agro-waste sugarcane bagasse ash from three brazilian sugarcane mills and obtaining biosilica from ash
    2023 - ROVANI S.; SANTOS, J.J.; CARVALHO, F.B.; RAMOS, N.P.; SALDANHA, M.; MORANDI, M.B.A.; FUNGARO, D.A.
    The interest in transforming biomass into new sources of energy and new materials has been encouraging studies around the world. The ash resulting from the burning of straw and sugarcane bagasse, for example, is a material rich in silica. In the present study, samples of fly ash and bottom ash from sugarcane residues were collected in three different mills (Cerradinho Iracema and Guaíra), located in regions where the soils are classified as oxisols. The ashes were characterized by XRD, EDX, ICP-OES, SEM, FTIR spectroscopy and TGA/DTG techniques. Most ash samples showed silica as the main constituent (42-69%) and silica in crystalline form in all. Biosilica was obtained from ash samples using alkali extraction and acid precipitation. The physical and chemical properties of the extracted biosilica are described. The biosilica samples have amorphous phases and purity ranged from 93 to 97 wt.%. The results showed that the different origins of sugarcane residue ash used as raw material did not affect the quality of the extracted biosilica.
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    Artigo IPEN-doc 27707
    Study of renewable silica powder influence in the preparation of bioplastics from corn and potato starch
    2021 - AZEVEDO, LUCIANA C. de; ROVANI, SUZIMARA; SANTOS, JONNATAN J.; DIAS, DJALMA B.; NASCIMENTO, SANDI S.; OLIVEIRA, FABIO F.; SILVA, LEONARDO G.A.; FUNGARO, DENISE A.
    In the present study, 0.5–1.5% silica powder, from sugarcane waste ash, was incorporated into corn and potato starch bioplastics doped with sodium silicate solution to improve the properties of elongation at break and increase the thermal resistance of the bioplastics. The starch-based bioplastics were produced by casting and characterized by color analyses, transparency, opacity apparent, humidity, thickness, tensile strength, elongation at break, FTIR, DSC, SEM, and biodegradation assay. The addition of 0.5% of silica powder improved the elongation at break of the corn starch-based bioplastics. The sample CS5-P0.5 presented the highest percentage of elongation at the break among the studied samples, increased from 59.2% (without silica powder) to 78.9% (with silica powder). For potato starch bioplastic the addition of 0.5% of silica powder did not improve elongation at break but increased the thermal resistance. Increased until 17 °C for PS5-P0.5 sample and until 11 °C for PS7.5-P0.5 sample. The bioplastics of potato starch were biodegraded in 5 days, and those of corn starch took almost 40 days. Silica powder inhibited the growth of fungi in starch bioplastics.
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    Artigo IPEN-doc 27702
    Uranium removal from aqueous solution using macauba endocarp-derived biochar
    2021 - GUILHEN, SABINE N.; ROVANI, SUZIMARA; ARAUJO, LEANDRO G. de; TENORIO, JORGE A.S.; MASEK, ONDREJ
    The main aim of this study was to evaluate options for addressing two pressing challenges related to environmental quality and circular economy stemming from wastage or underutilization of abundant biomass residue resources and contamination of water by industrial effluents. In this study we focused on residues (endocarp) from Macaúba palm (Acrocomia aculeata) used for oil production, its conversion to activated biochar, and its potential use in uranium (U) removal from aqueous solutions. Batch adsorption experiments showed a much higher uranyl ions (U(VI)) removal efficiency of activated biochar compared to untreated biochar. As a result of activation, an increase in removal efficiency from 80.5% (untreated biochar) to 99.2% (after activation) was observed for a 5 mg L 1 initial U(VI) concentration solution adjusted to pH 3 using a 10 g L 1 adsorbent dosage. The BET surface area increased from 0.83 to 643 m2 g 1 with activation. Surface topography of the activated biochar showed a very characteristic morphology with high porosity. Activation significantly affected chemical surface of the biochar. FTIR analysis indicated that U(VI) was removed by physisorption from the aqueous solution. The adsorbed U(VI) was detected by micro X-ray fluorescence technique. Adsorption isotherms were employed to represent the results of the U adsorption onto the activated biochar. An estimation of the best fit was performed by calculating different deviation equations, also called error functions. The Redlich-Peterson isotherm model was the most appropriate for fitting the experimental data, suggesting heterogeneity of adsorption sites with different affinities for uranium setting up as a hybrid adsorption. These results demonstrated that physical activation significantly increases the adsorption capacity of macauba endocarp-derived biochar for uranium in aqueous solutions, and therefore open up a potential new application for this type of waste-derived biochar.
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    Resumo IPEN-doc 27665
    Effect of experimental variables on the extraction of nanosilica prepared by sugarcane bagasse ash
    2020 - 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.
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    Artigo IPEN-doc 27252
    Fast, efficient and clean adsorption of bisphenol-A using renewable mesoporous silica nanoparticles from sugarcane waste ash
    2020 - ROVANI, SUZIMARA; SANTOS, JONNATAN J.; GUILHEN, SABINE N.; CORIO, PAOLA; FUNGARO, DENISE A.
    Even with all the biological problems associated with bisphenol-A (BPA), this chemical is still being widely used, especially in thermal paper receipts. In this study, renewable mesoporous silica nanoparticles (MSN), obtained from sugarcane ash, functionalized with hexadecyltrimethylammonium (CTAB) were applied as an adsorbent in the removal of BPA from the aqueous solution. The versatility of this material and its BPA adsorption capacity were tested at different pH values, being practically constant at pH between 4 and 9, with a slight increase in pH 10 and a greater increase in pH 11. The removal time evaluation indicates a very fast adsorption process, removing almost 90% of BPA in the first 20 min of contact. The kinetic model indicates a monolayer formation of BPA molecules on the MSN-CTAB surface. The maximum adsorption capacity (Qmax) was 155.78 mg g-1, one of the highest found in literature, and the highest for material from a renewable source.
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    Artigo IPEN-doc 27156
    Biodegradable films derived from corn and potato starch and study of the effect of silicate extracted from sugarcane waste ash
    2020 - AZEVEDO, LUCIANA C. de; ROVANI, SUZIMARA; SANTOS, JONNATAN J.; DIAS, DJALMA B.; NASCIMENTO, SANDI S.; OLIVEIRA, FABIO F.; SILVA, LEONARDO G.A.; FUNGARO, DENISE A.
    The growing concern with the amount of plastic materials found in the oceans makes it necessary to develop biodegradable materials that have low toxicity to marine animals and humans, but at the same time are resistant to the actions of microorganisms such as fungi or bacteria. On the other hand, agricultural waste rich in inorganic materials (such as silica) is often discarded, while it could be reused as a source of raw material. Considering these points, sodium silicate solution extracted from sugarcane waste ash was utilized to prepare biodegradable bioplastics based on corn starch and potato starch. The starch-based bioplastics were produced by casting and characterized by several physical-chemical techniques evaluating tensile strength, elongation at break, color analyses, transparency, opacity, moisture, and biodegradation assay. Bioplastics prepared with corn starch presented better physical, mechanical, and thermal properties and optical quality than bioplastics based on potato starch. The samples called CS3 and PS3, with 5.0% glycerol, were the most resistant to tensile strengths of 0.73 and 0.36 MPa, respectively. On the other hand, the highest elongation at break values were found for the samples with 7.5% glycerol (CS9, 52.90% and PS9, 49.33%). Corn starch-based bioplastics were more thermally resistant (CS3, 152.86 °C and CS9, 135.20 °C) when compared to potato starch-based bioplastics (PS3, 140.39 °C and PS9, 127.57 °C). In general, the addition of sodium silicate solution improved the mechanical and thermal properties of both types of bioplastics. The potato starch-based bioplastics were biodegraded in 5 days, while those made from corn starch took almost 40 days. The inclusion of sodium silicate inhibited fungal growth for both corn starch and potato starch bioplastics. The results suggest that sodium silicate solution obtained from renewable sources can be incorporated into starch-based bioplastics for production of biodegradable packaging with antifungal activity.
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    Artigo IPEN-doc 26782
    Extração de sílica a partir das cinzas de resíduo da cana-de-açúcar em diferentes condições de extração alcalina
    2019 - FUNGARO, D.A.; ROVANI, S.
    Uma amostra de cinzas geradas durante a queima de resíduos de cana-de-açúcar foi triturada com NaOH sólido variando-se a relação cinzas: NaOH (m/m). As misturas foram submetidas ao processo de fusão a 450 oC por 1 h. Após o resfriamento, a sílica da massa fundida foi lixiviada para a fase líquida na forma de silicato de sódio. Seguindo a separação do sólido e do líquido, partículas de sílica foram precipitadas pela adição de ácido sulfúrico até pH 7 à solução de silicato de sódio. O rendimento das amostras mostrou-se constante e uma pureza de 89% foi alcançada. As amostras de cinzas e de sílica produzidas foram caracterizadas por difração de raios-X, fluorescência de raios-X e análise elementar.
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    Artigo IPEN-doc 26758
    Caracterização físico-química das propriedades de cinzas de cana-de-açúcar de diferentes usinas brasileiras
    2019 - ROVANI, S.; CARVALHO, F.; SANTOS, J.; RAMOS, N.; MORANDI, M.; SALDANHA, M.; FUNGARO, D.
    O interesse em transformar biomassa em novas fontes de energia e novos materiais vem fomentando estudos em todo o mundo. As cinzas resultantes da queima de palha e bagaço de cana, por exemplo, é um material rico em sílica. No presente estudo, amostras de cinzas de resíduos de cana-de-açúcar foram coletadas nas usinas de Cerradinho (Chapadão do Céu, GO), Iracema (Iracemápolis, SP) e Guaíra (Guaíra, SP), localizadas em regiões onde os solos são classificados como Latossolos. As cinzas foram caracterizadas pelas técnicas de XRD, EDX, MEV, espectroscopia no IV e DTG. A maioria das amostras de cinzas apresentou sílica como principal constituinte (42-69%) e a sílica na forma cristalina em todas. Diferenças significativas nas concentrações de outros elementos foram observadas.
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    Resumo IPEN-doc 26531
    Comparative study of methods for the synthesis of silica nanoparticles from sugarcane waste ash
    2019 - ROVANI, SUZIMARA; FUNGARO, DENISE; CARVALHO, FELIPE; SANTOS, JONNATAN
    Adding 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.
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    Capítulo IPEN-doc 26704
    Removal of Crystal Violet dye from aqueous solution using ash-based adsorbent materials
    2019 - FUNGARO, DENISE A.; ROVANI, SUZIMARA; BERTOLINI, THARCILA C.R.; FILHO, FLAMARION F.
    Crystal Violet (CV) is widely used for various purposes and enters into the aquatic systems from the effluents of textile, paint, medical and biotechnological industries. A considerable amount of this dye is lost during manufacturing and processing operations. Contaminated wastewater containing CV must be treated before releasing in the environment because it is highly cytotoxic and carcinogenic to mammalian cells, present mitotic poisoning nature and is nonbiodegradable being classified as a recalcitrant molecule. This chapter reports the removal of CV dye from water using surfactant-modified zeolite from coal fly ash (MZSF), surfactant-modified zeolite from coal bottom ash (MZSB) and nanosilica from sugarcane waste ash (SiO2NP). The adsorbent materials were characterized to obtain chemical and mineralogical composition and others physicochemical properties. The adsorption kinetic of CV onto adsorbents was discussed using the pseudo-first order, pseudo-second order, and Elovich models. The Langmuir and Freundlich isotherm models were used to describe the equilibrium adsorption data. The maximum adsorption capacities were 36.7 mg g-1 and 21.1 mg g-1 for CV/MZSF and CV/MZSB, respectively. The adsorption process of CV/SiO2NP achieves equilibrium in 60 min of contact time, and the maximum adsorption capacity was 117.98 mg g-1. Application of the adsorbent materials synthesized from agricultural waste and coal combustion products can ensure the sustainability and cost-effectiveness of treating effluent containing CV dye, especially effluent from the textile industries generated in large quantity.