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Produção de biochar a partir de sabugo de milho: caracterização, adsorção de nitrogênio amoniacal e Scale-up da pirólise em reator de tambor rotativo

Fri, 03 Jul 2026 00:00:00 GMT

Title: Produção de biochar a partir de sabugo de milho: caracterização, adsorção de nitrogênio amoniacal e Scale-up da pirólise em reator de tambor rotativo Autor: Alberti, Schaline Winck Primeiro orientador: Silva, Edson Antonio da Abstract: Biochar has been extensively investigated as an adsorbent material for environmental applications. Although its use in agriculture has traditionally been associated with soil conditioning and carbon sequestration, biochar also exhibits high potential for wastewater treatment. In this context, the production of biochar from agricultural residues stands out as a sustainable alternative, enabling the valorization of these materials and the development of low-cost adsorbents, while providing additional environmental benefits such as CO₂ emission reduction and promotion of the circular economy. In this research project, biochar was produced by pyrolysis of corn cob, an abundant agricultural residue. Initially, the raw material was conditioned and characterized through thermogravimetric analysis (TGA), moisture and ash content determination, elemental composition, extractives content, lignin, and holocellulose analyses. Biochar production was conducted using a mixed 2 × 3 factorial experimental design, varying the carrier gas (N2 and autopyrolysis), particle size, and temperature, aiming to obtain a biochar with high cation exchange capacity and suitable properties for ionic adsorption. After the experimental design, segregation of corn cob composition during particle size separation was observed, as well as differences in adsorption capacities. This behavior motivated the production of powdered biochar under the best-defined atmospheric and temperature conditions, followed by post-pyrolysis acid treatment with phosphoric acid (H3PO4), resulting in the biochars denoted as Bp and BpH. Subsequently, physicochemical and functional characterizations were performed, including pH, point of zero charge (pHpzc), water retention capacity (WRC), electrical conductivity, Fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and total reflection X-ray fluorescence (TXRF), in addition to planned complementary analyses such as N2 physisorption, toxicity, and leaching tests. Characterization results indicated that acid treatment significantly altered the biochar surface, leading to reductions in pH, ash content, and conductivity, as well as modifications in surface functional groups. The pHpzc obtained for BpH was close to 3, providing a favorable condition for ammonium nitrogen (NH4+ < pKa = 8.8 < NH₃) adsorption. Considering the application in ammonium nitrogen removal, the BpH biochar (acid-treated) showed favorable kinetics, with the pseudo-first-order (PFO) model fitting the data, suggesting an overall kinetic controlled by external mass transfer and progressive site occupation, and an experimental ammonium nitrogen adsorption capacity (q) of ~53 mg g-1 in just 180 min. Equilibrium data showed sigmoidal behavior, and the Sips model provided the best fit, with an estimated maximum capacity of 64.07 mg g-1. In water from a fish farming depuration tank, an ammonium nitrogen adsorption capacity of 1.07 mg g-1 was obtained, similar to that obtained with a synthetic solution of similar concentration, in addition to reductions in concentrations of elements such as Na, P, K, and Ca, and inorganic carbon q = 3.90 mg g-1 and total carbon q = 2.73 mg g-1. In scale-up, corn cob pyrolysis in a rotary drum reactor resulted in a biochar yield of 24.86% and a pyrolytic liquid yield of 20.54% with acidic characteristics. The results demonstrated the viability of integrating corn cob valorization, biochar production, and its application in ammonium nitrogen removal, although operational adjustments and complementary evaluations are necessary for its continuous application. Publisher: Universidade Estadual do Oeste do Paraná Tipo do documento: Tese

Construção de modelos de predição Qsa(P)R com objetivos ambientais e toxicológicos

Wed, 03 Jun 2026 00:00:00 GMT

Title: Construção de modelos de predição Qsa(P)R com objetivos ambientais e toxicológicos Autor: Silva, Natalya Aline Barros Ribeiro da Primeiro orientador: Melo, Eduardo Borges de Abstract: This dissertation aimed to develop QSAR (Quantitative Structure–Activity Relationship) and QSPR (Quantitative Structure–Property Relationship) predictive models for the assessment of toxicological and environmental properties of organic compounds of regulatory interest. The study focused on three main groups of compounds: per- and polyfluoroalkyl substances (PFAS), pesticides classified as persistent organic pollutants (POPs), and substituted diphenyl ethers, including polymethoxylated, polyhydroxylated, methoxylated polychlorinated, and hydroxylated polychlorinated derivatives. The environmental persistence, high mobility, and toxic potential of these substances highlight the need for computational tools capable of supporting risk assessment in a rapid, reliable manner while reducing the dependence on experimental testing. The first study aimed to develop QSAR models to predict oral and inhalation toxicity parameters of PFAS in rats and mice using two-dimensional molecular descriptors and partial least squares (PLS) regression. The second study focused on developing QSAR models based on partial least squares discriminant analysis (PLS-DA) to classify the contact toxicity of pesticides toward honeybees (Apis mellifera), enabling the identification of structural patterns associated with the ecotoxicological potential of these compounds. The third study consisted of developing QSPR models to predict the soil organic carbon sorption coefficient (LogKoc) of substituted diphenyl ethers. Different algorithms for estimating LogP and LogS descriptors were compared, and the application of a hybrid descriptor (LogSp), obtained by combining lipophilicity and water solubility, was evaluated. The results demonstrated that LogP-based descriptors exhibited superior predictive performance, with the MLOGP algorithm showing the best performance among the theoretical methods evaluated. Furthermore, models developed using the hybrid Original_LogSp descriptor outperformed those based solely on individual descriptors, demonstrating that the combination of lipophilicity and water solubility improves the representation of physicochemical properties associated with soil sorption. The developed models exhibited satisfactory statistical robustness, stability, and high predictive performance, meeting the recommended validation criteria for QSAR/QSPR studies. The results demonstrate the potential of these computational approaches as valuable tools for toxicological and environmental assessment, contributing to the understanding of the molecular mechanisms underlying toxicity, mobility, and persistence of organic contaminants. Therefore, this dissertation provides predictive models that can support risk assessment, chemical regulation, and the development of safer compounds while reducing the need for experimental testing and promoting more sustainable strategies for protecting human health and the environment. Publisher: Universidade Estadual do Oeste do Paraná Tipo do documento: Dissertação

Integração de geotecnologias e análise hidrogeotécnica na segurança de barragem de um lago urbano sob eventos pluviométricos

Mon, 09 Mar 2026 00:00:00 GMT

Title: Integração de geotecnologias e análise hidrogeotécnica na segurança de barragem de um lago urbano sob eventos pluviométricos Autor: Costa, Leonan Coelho da Primeiro orientador: Makrakis, Maristela Cavicchioli Abstract: This research evaluated the safety of the barrage of the Municipal Lake of Toledo, Paraná, by means of the integration of geotechnologies and hydrogeotechnical monitoring, considering the influence of two pluviometric events on the hydrological dynamics of the microbacia of Sanga Panambi. The study was structured in two complementary studies. Initially, an integrated topobatimetric characterization of the Municipal Lake and Sanga Panambi was carried out, using surveys with GNSS RTK, ecobathmeter, unmanned aerial vehicle and geoprocessing tools, aiming to represent the morphology, or relay and armament capacity of two water bodies. Subsequently, hydrogeotechnical monitoring of the barrage was carried out, with records of precipitation, linimetric levels, phreatic line by half of piezometers and vacuums in the lake in Sanga Panambi, integrated by statistical and spatial analyses. The topobathymetric results will allow identifying flat areas, transition zones, deep depressions and assessment patterns, in addition to estimating normal volume of 49,759.69 m³ and maximum volume of 143,157.86 m³ for the Municipal Lake. The difference between the scenarios shows the regulatory function of the reservoir in the damping of pressure peaks. The hydrogeotechnical monitoring demonstrates a consistent relationship between precipitation events, elevation of the reservoir levels, increase in current vazões and temporary alterations in the piezometric conditions of the mass. The water located in the lake presents a lower amplitude of variation, while the points located in Sanga Panambi will respond more quickly and intensely to the rainwater. Despite the sensitivity of the structure to rainfall events, no critical conditions of geotechnical instability or compromise of hydraulic performance have been identified during the monitored period. It is concluded that the integration between geotechnologies and pluviometric, linimetric, fluviometric and piezometric data constitutes an efficient approach to characterize urban water systems, assess cliffs and support the monitoring of barrage security. The results provide technical subsidies for urban and environmental planning, cliff management, development and updating of barrage safety instruments and adoption of preventive measures in urban areas subject to hydrological variability. Publisher: Universidade Estadual do Oeste do Paraná Tipo do documento: Tese

Síntese e obtenção de catalisador à base de vidro soda-cálcico funcionalizado com NaOH para reações de transesterificação na produção de biodiesel e despolimerização do PET em PTA

Mon, 29 Jun 2026 00:00:00 GMT

Title: Síntese e obtenção de catalisador à base de vidro soda-cálcico funcionalizado com NaOH para reações de transesterificação na produção de biodiesel e despolimerização do PET em PTA Autor: Moreira, Luis Carlos Fagundes Primeiro orientador: Schneider, Ricardo Abstract: This study aimed to develop and evaluate heterogeneous catalysts produced from recyclable soda-lime vitreous waste, combined with eggshells and NaOH, for application in two environmentally relevant chemical pathways: the transesterification of vegetable oils for biodiesel production and the depolymerization of polyethylene terephthalate (PET) to obtain terephthalic acid (PTA). The proposal is based on the valorization of municipal solid waste through its transformation into sustainable catalytic materials, aligned with the principles of green chemistry and the circular economy. The samples were characterized using various analytical techniques, including Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, laser-induced optical emission spectroscopy (LIBS), X-ray diffraction (XRD), and particle size analysis by laser scattering. The results of these analyses confirmed significant structural and chemical changes in the glass matrix, such as the presence of hydroxylated groups, modification of the silicate network, the elimination of carbonates, and the incorporation of elements such as sodium and calcium, which are directly associated with catalytic activity in basic reactions. Particle size analysis, through statistical analysis of the data, confirmed the good uniformity in sphere size, validating the methodology used in their manufacture. In the catalytic tests, we obtained a 60% methyl ester content in the production of biodiesel from the transesterification of soybean oil, and conversions exceeding 70% in the depolymerization of PET for PTA recovery, even under moderate operating conditions. These results highlight the potential of the developed catalysts as substitutes for conventional catalysts. Future studies aimed at improving their physicochemical properties, as well as optimizing reaction parameters and conditions, could increase their catalytic efficiency. Publisher: Universidade Estadual do Oeste do Paraná Tipo do documento: Dissertação