SUZIMARA ROVANI

SUZIMARA ROVANI

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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.
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.
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.
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.
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.
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.
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.
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.
An alternative and simple method for the preparation of bare silica nanoparticles using sugarcane waste ash, an abundant and despised residue in the Brazilian industry
2019 - ROVANI, SUZIMARA; SANTOS, JONNATAN J.; CORIO, PAOLA; FUNGARO, DENISE A.
Sugarcane waste ash, a Si-rich waste product, is generated in large quantities and creates a serious disposal problem in the Brazilian ethanol-sugar industry, affecting the environment and public health. Here, a simple method capable of generating bare silica nanoparticles utilizing this residue is demonstrated. Firstly, the crystalline silica present in sugarcane waste ash (SWA) was converted into amorphous by melting a mixture of sodium hydroxide and SWA at 550 °C for 1 h. The silica nanoparticles (SiO2NPs) were formed by lowing pH. This production process of SiO2NPs from SWA was optimized varying the ash:NaOH mass ratio, increasing the silica extraction up to 96%. The sample’s composition was characterized by total X-ray fluorescence spectroscopy, morphology and physical-chemical properties were investigated by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction, specific surface area measurements, Fourier-transform infrared spectroscopy (FTIR) and thermogravimetric analyses (TGA), followed by use as adsorbent for the removal of methylene blue dye. With this process of extraction, nanoparticles smaller than 100 nm were generated, with a surface area of 63 m2 g-1 and a maximum adsorption capacity of 37 mg g-1 for methylene blue. The results indicate a successful process for obtaining an adsorbent from an industrial waste product using a cost effective and rapid synthesis procedure rendering renewable product.
Application of biochar from agro‑industrial waste in solid‑phase extraction for the determination of 17β‑estradiol from aqueous solution
2019 - ROVANI, S.; MEDEIROS, L.F.; LIMA, E.C.; FERNANDES, A.N.
In this study, the biochar produced from coffee wastes and eucalyptus sawdust was employed as an adsorbent in solid-phase extraction devices for the determination of 17β-estradiol from aqueous solution. Parameters such as adsorbent mass, solvent type, eluent volume, ionic strength, breakthrough volume, and the cartridge reuse were evaluated. The best experimental conditions for solid-phase extraction concerning adsorbent mass, elution solvent, eluent volume, ionic strength, breakthrough volume, and cartridge reuse were established. The most suitable conditions for 1.0-mL cartridge were: mass of 50 mg, elution solvent 5.0 mL of acetonitrile/water 90:10 (v:v), 0.003 mol L−1 NaCl concentration, and 17β-estradiol solution volume 50.0 mL. The solid-phase extraction results showed that, although 17β-estradiol recovery was about 60%, the removal efficiency was 100% and the cartridges of 200 and 500 mg can be reused eight and four times, respectively, without any decrease in adsorption capacity. The results demonstrate the potential use of biochar as new adsorbent in solid-phase extraction devices for the removal of estrogens in aqueous solution.

SUZIMARA ROVANI

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