http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/4323 2025-09-27T04:19:43Z http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/9667 Título: Proposta para reutilização de corantes da indústria têxtil através da aplicação de nanomateriais em processos adsortivos por meio da celulose bacteriana Autor: SOUTO, Thaís Jeruzza Maciel Póvoas Primeiro orientador: MORAES, Alex Souza Abstract: Currently, the state of the environment has demonstrated how important/vital it is to invest in technologies that work with systems that allow the reuse or disposal of products, since technologies are aimed at greater sustainability, either by reducing the load of pollutants and effluents or reusing these environmental liabilities in a practical application, generating savings. Thus, to mitigate the environmental impacts of the production of dyes and organic pigments from the chemical processes existing within the textile industry, between its molecule and its synthesis, this work sought to investigate the structural and morphological properties of the bioadsorbent, for application in adsorptive processes in the generation of a by-product and promoting the characterization of synthetic commercial dyes. As a bioadsorbent material, bacterial cellulose was used as an alternative method of removing dyes through adsorption, functioning as an absorbent capable of separating effectively due to its purity, elasticity, and biocompatibility. To analyze the adsorption parameters made by bacterial cellulose, the study methodology used was the UV/Vis analysis, ICP-OES, Principal Component Analysis (PCA) and Thermogravimetric Analysis (TGA). Thus, it was analyzed how much the use of recyclable technologies can promote a new way of using dyes, since nanofiltration can be contemplated by the membrane separation technique, which implies the promotion of sustainability. As results obtained, it was observed that the textile dyes, through the adsorption kinetics, presented a removal rate for C8 of approximately 16%, for C10. Adsorption kinetics can be well expressed by the pseudo-second order model, indicating the importance of chemical adsorption in the process. When carrying out the Thermogravimetric Analysis, it was noticed that the bacterial cellulose begins to lose its structural stability at 360ºC, reaching the apex at 555ºC, disappearing from the experiment, forming a subdye for reuse in a new dyeing process. In this way, it was concluded that with the amount of metals identified in the chemical composition of the dye, it is pointed out how important the use of bacterial cellulose was, also, in the promotion of disposal, since the metal develops resistance to the environment, and likewise would be a source of inorganic pollutant with high mobility and high toxicity. After analyzing the data, the result is the importance of Bacterial Cellulose (BC) in the removal of dyes in textile industrial effluents, as it degrades at a certain temperature and the dye becomes purified to be reused, thus protecting the environment and human health. Instituição: Universidade Federal Rural de Pernambuco Tipo do documento: Tese 2022-12-16T00:00:00Z http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/8570 Título: Estudo eletroquímico e eletroanalítico dos biomarcadores de doenças humanas 7-metil-guanosina, orto tirosina e 3-nitro-tirosina Autor: NASCIMENTO, Raphael Fonseca do Primeiro orientador: OLIVEIRA, Severino Carlos Bezerra de Abstract: Oxidative damage in biological molecules, such as double-stranded DNA (dsDNA) and proteins are associated with numerous pathologies in the human body, such as cancer. Thus, it is of great relevance to investigate the redox mechanisms that occur in vivo for different biological processes. The present study aims to investigate the redox behavior of the biomarkers of human diseases, 7-methyl-guanosine (7-mGuo), ortho-tyrosina (o-Tyr) and 3-nitro-tyrosine (3-NO2-Tyr) on glassy carbon electrode (GCE) using voltammetric techniques, such as cyclic voltammetry (CV), square wave voltammetry (SWV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS). The electrochemical results of o-Tyr and 3-NO2-Tyr were also compared with the para-tyrosine (p-Tyr). Electroanalytical methodologies for the detection and quantification of these species were also investigated and developed in the absence and presence of possible interferences. Oxidation of the 7-mGuo on GCE occurs in single step pH-dependent irreversible pathway with the transfer of one electron and one proton with formation of polymer products absorbing on the electrode surface. An oxidation mechanism of 7-mGuo has been proposed. An electroanalytical method for quantification of 7-mGuo at physiological pH, using GCE and DPV was proposed, with a detection limit of 3.26 μmol L-1 and limit of quantification of 10,88 μmol L-1. Electrochemical detection of 7-mGuo was also investigated in the presence of potential interference of guanine, guanosine and 7-methylguanine (7-mGua). The study showed that the anodic peak of 7-mGuo suffered no interference of these species, since oxidation occurs in a very different potential. In general, the p- and o-Tyr undergo oxidation in a single irreversible step pH-dependent, with the transfer of one electron and one proton, from the phenolic group to formation of Tyr phenoxy radical (Tyr●). However, while the p-Tyr● radical preferably polymerizes, forming a resistive film on the GCE surface, the o-Tyr● reacts preferentially with water with formation of o- and p-quinone derivatives, that are adsorbed and reversibly reduced on the GCE surface. In relation the 3-NO2-Tyr its oxidation occurs, in general, in two irreversible steps. The first step is pH-dependent, while the second is pH-independent, indicating the absence of protons in the process. The first process correspond to the oxidation of the phenolic group to form 3-NO2-Tyr●, which reacts in different ways, polymerizing, forming a resistive film on the GCE surface and/or being directly electro-oxidized to a cationic product (second step). The voltammetric data also showed that the 3-NO2-Tyr phenol group is more difficult to oxidize when compared to p- and o-Tyr molecules. Moreover, unlike p-Tyr and o-Tyr that present no cathodic peak, 3-NO2-Tyr suffers in acid medium electro-reduction in a single irreversible step with formation of two electroactive products. Such processes were assigned to the reduction of the nitro group to form hydroxylamine and amine. Thus, is clearly demonstrated that the nitro group attached, as well as the phenolic group position at the Tyr molecule, strongly influence its redox properties. The redox mechanism of o-Tyr and 3-NO2-Tyr are presented and discussed. A voltammetric method for detection and quantification of 3-NO2-Tyr in physiological medium using DPV was also proposed and a concentration range of 20 to 200 μmol L-1, presented a correlation coefficient of 0.998 and a detection limit of 6, 21 μmol L-1. The knowledge of redox mechanisms of the biomarkers of human diseases, 7-mGuo, o-Tyr and 3-NO2-Tyr, as well as the proposed electroanalytical methods for their quantification correlates and are important in the literature, as basic knowledge to future interpretation and applications in molecular biochemistry. Instituição: Universidade Federal Rural de Pernambuco Tipo do documento: Tese 2019-12-20T00:00:00Z http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/8568 Título: Determinação de disruptores endócrinos (bisfenol A e ftalatos) em utensílios e brinquedos para lactentes usando HPLC-UV-VIS e estudo de bioacessibilidade Autor: LIMA, Gabriel Acioly de Primeiro orientador: LAVORANTE, André Fernando Abstract: Bisphenol A and phthalates are chemical compounds used in the production of polymers. Studies show that these compounds are endocrine disruptors and when in contact with the body affect the hormonal system, generating various health problems to the individual. Thus, this research aims to develop a method for the determination of bisphenol A and dibutyl phthalates (DBP), bis-2-ethylhexyl (DEHP), di-n-octyl (DNOP) and diisodecyl (DIDP) in utensils and toys intended for infants, as well as to evaluate the bioaccessibility of these compounds in artificial saliva. For this, ultrasound assisted liquid extraction and detection on HPLC-UV-VIS at 230 nm were performed. Gradient elution was performed with a binary mixture of methanol (solvent B) and deionized water (solvent A) ranging from 70% B to 93% B from 3 min to 5 min at a flow rate of 1.0 mL min-1. The column used was Agilent C18 and had a total elution time of 20 min. After establishing the analysis parameters, the method was validated, finding detection limits of 0.003 to 0.051 mg L-1 and quantitation limits of 0.011 to 0.155 mg L-1 for bisphenol A and phthalates analyzed. Extraction in an ultrasonic system was performed with chloroform and optimized with a factorial design 24, where optimal conditions were defined as 1.50 g of sample in 10 mL of chloroform, with ultrasound extraction time of 20 min at 65 °C. Matrix effect tests showed that the method does not suffer this type of interference and recovery studies showed values from 73.2 to 103 %. Ten commercially acquired samples from the city of Recife-PE were analyzed, and the results presented phthalate concentration values between 0.101 and 30.808 mg Kg-1, being considered below the limits established by ANVISA, and bisphenol A concentration values between 0.060 and 21.131 mg Kg-1. Migration tests with artificial saliva were performed and the results showed that all samples presented bisphenol A migrations in concentrations allowed by the current legislation. In nine samples, DBP migration values were detected above those allowed by ANVISA. One of the samples analyzed revealed inconsistencies in the packaging information as it claimed to have no phthalates. The proposed method has been shown to be suitable for analysis of endocrine disruptors in utensils and toys intended for infants within the parameters required by ANVISA. Instituição: Universidade Federal Rural de Pernambuco Tipo do documento: Dissertação 2019-12-20T00:00:00Z http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/8567 Título: Grilo preto (Gryllus assimilis) como candidato a material de referência certificado : um estudo de homogeneidade e massa mínima Autor: PEREIRA, Raphael Henrique de Moura Primeiro orientador: LAVORANTE, André Fernando Abstract: The analytical quality is a parameter of relevance in chemical analyses for guaranteeing the reliability and traceability of analytical results. Normally, it is achieved using Certified Reference Materials – CRM. However, not all matrices are available as CRMs in the market. As the edible insects are considered the future food in terms of meat substitution, the CRM production using this matrix type becomes fundamental. The present work has studied the utilization of black cricket insect (Gryllus assimilis) as a RM candidate by means of preparation, bottling and minimum mass determination and homogeneity assays, as well as the nutrient determination of this matrix. The sample preparation process consisted of milling, sieving and freeze-drying, followed by quartering and bottling of the material with posterior irradiation. The obtained batch was composed by 40 bottles containing 4 g of dried material and with maximum particle size of 80 μm. The residual humidity determination was carried out by the comparison of two drying methods (oven and freeze-dryer), while the mass minimum determination was performed by comparing the obtained values for analytical portions of 20 mg, 150 mg and 500 mg, applying the EDXRF (Cl, P and S) and FAAS (Cu, Fe, Mn and Zn) techniques. As the main property of the RM candidate, the homogeneity was assessed by the FAAS technique for evaluating the distribution of Cu, Fe, Mn and Zn in the material. The chemical characterization of the candidate was carried out through the EDXRF and ICP-OES techniques. The candidate showed residual water content of 7%, in which the best method for this determination was oven-drying. The results of minimum mass assay indicated that, among the analytical portions studied, 500 mg was the recommended minimum mass for the use of RM candidate, however, for some chemical elements, lower masses could be employed (between 150 e 500 mg). The preparation and bottling of the RM candidate was considered adequate since the homogeneity has been demonstrated for Cu, Fe, Mn and Zn at the 95% confidence level. With the chemical characterization, the material, besides of being protein source, had high concentrations of the Ca, Cl, K, Mg, Na, P and S nutrients, showing nutritional relevance. Instituição: Universidade Federal Rural de Pernambuco Tipo do documento: Dissertação 2019-12-19T00:00:00Z