Remoção e recuperação de ions Hg (II) utilizando quitosana natural e reticulada

Orientador : Marisa Masumi BeppuDissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia QuimicaResumo: A quitosana vem sendo largamente investigada para remoção e recuperação de íons metálicos a partir de efluentes industriais. Este material, obtido por desacetilação da quitina, possui em sua estrutura grupos amino e hidroxilas, bastante reativos, que o toma um polímero de grande interesse industrial. Este trabalho objetivou estudar a adsorção e dessorção de íons Hg(II) em quito sana, utilizando-se o método estático e dinâmico de adsorção. Uma etapa de reticulação com glutaraldeído ou epic1oridrina, foi proposta, visando maximizar a adsorção e ainda caracterizar quais grupos funcionais estão envolvidos na adsorção. A reação de reticulação com glutaraldeído ou epic1oridrina, toma os grupos amino ou hidroxilas indisponíveis, respectivamente, podendo-se caracterizar a influência destes grupos na etapa de adsorção. O estudo de adsorção estática foi feito utilizando-se membranas de quito sana na forma natural ou reticulada, variando-se o pH da fase fluida e a concentração dos íons de Hg(II). O estudo de dessorção foi feito utilizandose NaCl, CaCl2 e EDTA como eluente, de modo a verificar a natureza da força de adsorção. A adsorção dinâmica foi feita utilizando-se quito sana reticulada com glutaraldeído, variando-se: vazão, tamanho da coluna, concentração do soluto e tamanho da partícula do adsorvente. Observou-se que a quito sana reticulada com glutaraldeído apresentou maior capacidade de adsorção e que a adsorção foi influenciada pelo pH da solução. O estudo de dessorção mostrou que as espécies metálicas podem ser recuperadas, utilizando-se NaCl como eluente e que a força de adsorção é principalmente de natureza eletrostática. A cinética de adsorção mostrou que não houve diferença na taxa para os três tipos de quito sana, indicando um possível efeito de filme sobre a superfície do adsorvente. A capacidade de adsorção para os experimentos em coluna foi em tomo de 75% daquela avaliada sobre condições de equilíbrio (método estático) e as espécies metálicas puderam ser recuperadas utilizando-se um pequeno volume da solução eluente. O comportamento de adsorção e dessorção dos íons Hg(II) a partir de um efluente industrial foi avaliado, e observou-se o potencial deste material, mesmo a baixas concentrações dos íons metálicosAbstract: Chitosan has been investigated for removal and recovery of heavy metals from industrial effluents. This material, obtained by deacetylation of chitin, contains amino and hydroxyl groups in its structure. These groups, sufficiently reactive, have made this polymer very interesting for many industries applications. The aim of this work was to study the adsorption and desorption of Hg(II) ions in chitosan, using the static and dynamic methods of adsorption. Crosslinking with glutaraldehyde and epichlorohydrin was proposed, aiming to maximize the recovery of metallic species and to understand the adsorption mechanism. These species were chosen in order to verify which groups participate in the adsorption. The study of static adsorption was made using raw and crosslinked membranes of chitosan, as a function of pH and concentration of Hg(II) ions. The desorption was studied using NaCI, CaCl2 and EDTA as eluent, in order to verify the kind of adsorption. The dynamic adsorption was done using glutaraldehyde-crosslinked chitosan, as a function of the particle size, concentration, size of column and flow rate. The capacity of adsorption on glutaraldehyde-crosslinked chitosan was higher than that on raw chitosan and it was found to be pH-dependent. The desorption study showed that metallic species can be easily recovered, using NaCI as eluent, and that the adsorption force is mainly of electrostatic nature. The kinetics of adsorption showed there is no difference in the rate for the three kinds of chitosan, indicating a possible film effect at the surface of adsorbent. For column experiments the adsorption capacity was around 75% of the value found on equilibrium conditions (static method) and could be recovered using a small volume of eluent solution. The behavior of adsorption and desorption of Hg(lI) ions, from an industrial effluent, was evaluated and it was observed the potential of chitosan as adsorbent, even in low concentrations of metallic speciesMestradoMestre em Engenharia Químic

Competitive adsorption of copper and mercury ions on natural and crosslinked chitosan membranes

Orientadores: Marisa Masumi Beppu, Eric GuibalTese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia QuimicaResumo: Nos últimos anos, a quitosana, um polissacarídeo linear obtido através da desacetilação da quitina, tem sido descrito como um biopolímero para remoção de metais pesados a partir de efluentes industrias, devido a presença de grupos amino e hidroxilas em suas estruturas, os quais podem atuar como sitios ativos. Vários métodos têm sido utilizados para modificar a quitosana natural, como reticulação com glutaraldeído (GLA) ou eplicloridrina (ECH). As propriedades de adsorção de diferentes espécies metálicas individuais vêm sendo largamente estudadas, embora, a maioria dos efluentes industriais não contenha somente uma espécie metálica, mas várias. Este trabalho foi proposto objetivando-se investigar o fenômeno de adsorção em um sistema binário sintético, constituído dos íons Hg(II) e Cu(II), utilizando-se quitosana natural ou reticulada como bioadsorvente. Membranas de quitosana foram obtidas e seguiu-se com o levantamento das propriedades cinéticas e de equilíbrio, em sistemas monocomponentes e de mistura. O estudo de equilíbrio monocomponente mostrou que a quitosana possui maior afinidade pelos íons Hg(II) quando comparado aos íons Cu(II). Observou-se que a reticulação aumentou a capacidade de adsorção. Para os sistemas de misturas pôde-se observar que o Hg é menos afetado pela presença de Cu. Usando somente dados monocomponentes de equilíbrio os efeitos de adsorção competitiva dos diferentes íons na mistura foram avaliados utilizando o modelo de Langmuir Estendido e a Teoria da Solução Adsorvida Ideal (IAST). A modelagem da cinética de adsorção mostrou que a difusão externa (efeito de filme) é menos significativa que a difusão intrapartícula para íons Cu(II), e o contrário para os íons Hg(II). Ao aumentar a concentração de Hg, a cinética do Cu foi fortemente influenciada. Obtiveram-se bons resultados de dessorção para os íons Hg(II) utilizando-se soluções de NaCl e KI como eluente, e para os íons Cu(II) utilizando-se H2SO4 e tiouréia. Estes resultados indicam que para os íons Hg(II) a adsorção pode-se dar tanto por quelação, troca-iônica ou atração eletrostática, enquanto para os íons Cu(II), o mecanismo de quelação é mais significativo. Utilizaram-se as técnicas de espectroscopia de foto-elétrons (XPS) e estrutura fina de absorção de raios-X (EXAFS) utilizando radiação Síncrotron. Pela técnica de XPS, pôde-se observar que as espécies de Cu(II) são reduzidas sobre a quitosana reticulada com glutaraldeído. A técnica EXAFS confirmou que a adsorção destas espécies se dá nos grupos amino e hidroxilas, embora não tenha sido possível diferenciá-los entre siAbstract: Recent investigations have described chitosan, a linear polysaccharide obtained from deacetylation of chitin, as a suitable biopolymer to remove heavy metal ions from wastewater, since the amino and hydroxyl groups present in its structure can act as chelating sites. Several methods have been used to modify natural chitosan, such as crosslinking with glutaraldehyde (GLA) or epiclorohydrin (ECH). The adsorption of different heavy metal ions in single systems has been investigated. However, in real systems it is more common to observe several ions in solution, which may interfere and compete for adsorption sites. The aim of this work was to study the adsorption of copper and mercury ions on natural and crosslinked chitosan membranes (single and binary systems), in order to evaluate the competition of different metallic ions for the chelation sites of chitosan. Chitosan membranes were prepared and used to obtain the single and binary kinetic and equilibrium properties. The values of adsorption capacity for mercury ions were higher than those for copper ions for all kinds of chitosan membranes. The highest adsorption capacities were found for crosslinked chitosan. It is possible to notice that the presence of copper ions in the mixture has a more significant impact on mercury adsorption than the other way around. Using only the monocomponent data, the competitive adsorption effects of the different ions in mixture were evaluated using the Langmuir Extended Model and Ideal Adsorbed Solution Theory (IAST). The adsorption kinetic modeling showed that external diffusion (boundary layer) is more significant than intraparticle diffusion for copper ions and the opposite for mercury ions. By increasing the mercury concentration, the copper kinetics was strongly influenced. The best desorption results were obtained for Hg(II) ions using NaCl and KI solutions as elutants. For Cu(II) ions, the best results were obtained by using H2SO4 and thioreia solutions. These results indicated that the adsorption mechanism for Hg(II) ions on chitosan is either by chelation, ion-exchange and electrostatic attraction, while for Cu(II) ions the chelation is more significant mechanism. X-ray photoelectron spectroscopy (XPS) and extended X-ray absorption fine structure spectroscopy (EXAFS) were used to investigate the complex properties. The XPS results showed a possible reduction of Cu(II) ions on glutaraldehydecrosslinked chitosan. The EXAFS results confirmed that copper and mercury adsorption could have happen both on amino and hydroxil groupsDoutoradoEngenharia de ProcessosDoutor em Engenharia Químic

Enhancement of the catalytic activity of Mg/Al layered double hydroxide for glycerol oligomers production

In this study, the impact of rehydration on the catalytic properties of Mg/Al layered double hydroxides (LDH) for glycerol ligomerization was assesed. Although previous works have employed other LDH derived materials in this reaction, little information on recyclability is published. After observing the initial results on how basicity and surface area were related to the catalytic activty, an LDH modification strategy was developed with the addition of acetic acid. Changes on the basic site distribution were noticed and consequently, selectivity to diglycerol was improved. The best catalytic performance (reaction with 4 wt% cat., at 240 °C for 8 hours) led to 64% of glycerol conversion (XGly) and 37% of diglycerol selectivity (Sdi). Aditionally, reciclying of modified LDH was better than the non acid treated material, presenting higher yield of diglycerol. Catalyst deactivation was related to the harsh reaction conditions and to the blockage of active species by impurities. Loss of metallic species by leaching to the reaction products was not oberseved, an advantage in comparison with previous works.Funding for this research was provided by: Conselho Nacional de Desenvolvimento Científico e Tecnológico (APQ-1015-3.06/14, E1-0079-0004301) Consejería de Economía, Innovación, Ciencia y Empleo, Junta de Andalucía (P20_00375, UMA18-FEDERJA-126) Funding for open access charge: Universidad de Málag

PARTICIPAÇÃO DE JOVENS TENISTAS EM COMPETIÇÕES DE 12 A 16 ANOS: A PERCEPÇÃO DE UM GRUPO DE TREINADORES

The aim of the study was to describe how tennis players from 12 to 16 years old participate in youth competitions, according to the perception of a group of coaches. The study was of the descriptive-exploratory type, of qualitative nature. Semi-structured interviews were conducted with 11 tennis coaches from four Brazilian states. The results allowed us to consider that there is a need to propose and implement tennis competitions models that are more suitable for young tennis players. It was concluded, according to the interviewees’ view, that many athletes end up competing without motivation, causing many dropouts, resulting from a bad transition from the Tennis 10’s stages to the traditional model. On the other hand, it was noticed the emergence of ideas arising from the diversification of suitable and attractive competitions for different groups of tennis players in the age group.El objetivo del estudio fue describir cómo se realiza la participación de tenistas de 12 a 16 años en las competiciones, según la percepción de un grupo de entrenadores. El estudio fue de tipo descriptivo-exploratorio, de carácter cualitativo. Se realizaron entrevistas semiestructuradas con 11 entrenadores de tenis de cuatro estados brasileños. Los resultados permitieron considerar que existe la necesidad de proponer e implementar modelos de competiciones de tenis más adecuados para los jóvenes. Se concluyó, según la visión de los entrevistados, que muchos tenistas terminan compitiendo sin motivación, provocando muchos abandonos, resultado de una mala transición de las etapas de Tennis 10’s al modelo tradicional. Por otro lado, se notó el surgimiento de ideas derivadas de la diversificación de competiciones adecuadas y atractivas para diferentes grupos de tenistas de este grupo de edad.O objetivo do estudo foi descrever como transcorre a participação de tenistas dos 12 aos 16 anos nas competições infantojuvenis, segundo a percepção de um grupo de treinadores. O estudo foi do tipo descritivo-exploratório, de cunho qualitativo. Foram realizadas entrevistas semiestruturadas com 11 treinadores de tênis de quatro estados brasileiros. Os resultados permitiram considerar que existe a necessidade de se propor e implementar modelos de competições de tênis mais adequados aos jovens. Concluiu-se, conforme a visão dos entrevistados, que muitos atletas acabam competindo sem motivação, ocasionando muitas desistências, decorrentes de uma má transição dos estágios do Tennis 10’s para o modelo tradicional. Por outro lado, percebeu-se o surgimento de ideias advindas da diversificação de competições adequadas e atrativas para diversos grupos de tenistas nessa faixa etária

Evaluating the effectiveness of a training program that builds teachers' capability to identify and appropriately refer middle and high school students with mental health problems in Brazil: an exploratory study

Background: in Brazil, like many countries, there has been a failure to identify mental health problems (MHP) in young people and refer them to appropriate care and support. the school environment provides an ideal setting to do this. Therefore, effective programs need to be developed to train teachers to identify and appropriately refer children with possible MHP. We aimed to evaluate teachers' ability to identify and appropriately refer students with possible MHP, and the effectiveness of a psychoeducational strategy to build teachers' capability in this area.Methods: To meet the first objective, we conducted a case-control study using a student sample. To meet the second, we employed longitudinal design with repeated measures before and after introducing the psychoeducational strategy using a teacher sample. in the case control study, the Youth Self-Report was used to investigate internalizing and externalizing problems. Before training, teachers selected 26 students who they thought were likely to have MHP. Twenty-six non-selected students acted as controls and were matched by gender, age and grade. the underlying principle was that if teachers could identify abnormal behaviors among their actual students, those with some MHP would likely be among the case group and those without among the control group. in the longitudinal study, 32 teachers were asked to evaluate six vignettes that highlighted behaviors indicating a high risk for psychosis, depression, conduct disorder, hyperactivity, mania, and normal adolescent behavior. We calculated the rates of correct answers for identifying the existence of some MHP and the need for referral before and after training; teachers were not asked to identify the individual conditions.Results: Teachers were already able to identify the most symptomatic students, who had both internalizing and externalizing problems, as possibly having MHP, but teachers had difficulty in identifying students with internalizing problems alone. At least 50.0% of teachers learned to identify hypothetical cases as problematic and to make the appropriate referral, and 60.0% of teachers who before training could not identify normal adolescence learned to do so.Conclusions: the strategy was partially effective but could be improved mainly by extending its duration, and including discussion of actual cases.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Universidade Federal de São Paulo UNIFESP, Dept Psychiat, BR-04038030 São Paulo, BrazilUniversidade Federal de São Paulo UNIFESP, Dept Psychiat, LINC, BR-04038030 São Paulo, BrazilNatl Inst Dev Psychiat Children & Adolescents INP, São Paulo, BrazilUniversidade Federal de São Paulo UNIFESP, Dept Psychiat, BR-04038030 São Paulo, BrazilUniversidade Federal de São Paulo UNIFESP, Dept Psychiat, LINC, BR-04038030 São Paulo, BrazilWeb of Scienc

Production of chemically modified chitosan microspheres by a spraying and coagulation method

Chitosan microspheres can be used in several applications, as biomaterials, in biotechnology processes and as adsorbents. The control of particle size in microsphere production is important to make these applications viable. This study focuses on the production and morphological characterization of chitosan microspheres. Microspheres were prepared by a spraying and coagulation process. Particles underwent chemical modifications with glutaraldehyde, epichlorohydrin or acetic anhydride treatments. The microspheres presented a fairly good sphericity (0.74) but an irregular micro-surface morphology. The mean particle size (MPS) ranged from 140 to 281 mum and the mean standard deviation (MSD) from 119 to 238 mm. The conditions were modelled to provide desired MPS and MSD by using the response surface methodology (RSM).347352Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Characterization of resistance response of Coffea canephora genotypes to Meloiddogyne incognita (Est I2) root-knot nematode

Meloidogynose is prominent among the factors that limit yield in C. canephora in the western Amazon, Brazil. It is caused by species of “root-knot nematode”; the most important and aggressive of these species for coffee is M. incognita. The aim of this study was to assist the selection of resistant genotypes by characterizing the reaction of 32 C. canephora clones to M. incognita (Est I2). These genotypes are selected plants from the Germplasm Bank of Embrapa Rondônia of the botanical varieties Conilon, Robusta and intervarietal hybrids. The experiments were conducted under greenhouse conditions by inoculating six seedlings for each clone with 10 ml of suspension containing 5000 eggs of a pure inoculum of M. incognita. At 150 days after inoculation, evaluations were made of fresh weight of roots (FWR), total number of galls (NG), total number of eggs (NE), and the nematode reproduction factor (RF=final population/initial population). In contrast with the susceptible controls of arabica coffee (RF=1.2) and tomato plants (RF=31.3), six clones of the Conilon botanical variety, five clones of the Robusta botanical variety and eight intervarietal hybrids reacted as resistant to M. incognita, exhibiting RF < 1 and a reduced number of galls (NGmean = < 10). The clones identified as resistant in this study were integrated in the coffee breeding program in Rondônia for development of cultivars resistant to the root-knot nematode adapted to tropical conditions

Effects of the vacation period on the health-related physical fitness of schoolchildren

O objetivo do estudo foi verificar os efeitos do período de férias de verão nos níveis de aptidão física relacionada à saúde (ApFRS) de escolares do 7º e 8º ano do ensino fundamental. O delineamento do estudo caracteriza-se como observacional, considerado longitudinal de curto prazo. As avaliações físicas foram realizadas antes e após o período de férias escolares de verão. Os componentes da aptidão física analisados foram: Aptidão cardiorrespiratória- teste de corrida ou caminhada de 6 minutos, composição corporal- medidas de índice de massa corporal, circunferência de cintura e relação cintura:estatura, força/resistência muscular- teste de resistência abdominal (sit-up) e flexibilidade- teste de sentar e alcançar. Como análise estatística, utilizou-se o teste t pareado, adotando-se p≤0,05. Observou-se aumento significativo no índice de massa corporal, circunferência de cintura, relação cintura/estatura e flexibilidade após o período de férias. No entanto, não houve alterações significativas para aptidão cardiorrespiratória e força/resistência muscular. Além disso, analisando meninos e meninas separadamente, não foram encontradas diferenças para a relação cintura/estatura e apenas as meninas apresentaram melhorias na força/resistência muscular.The aim of the study was to verify the effects of the summer vacation period on the health-related physical fitness (HRPF) of students in the 7th and 8th grades of elementary school. The study design is characterized as observational, considered short-term longitudinal. Physical evaluations were carried out before and after the summer school vacation period. The components of physical fitness analyzed were: Cardiorespiratory fitness - 6-minute running or walking test, body composition- measures of body mass index, waist circumference and waist-to-height ratio, muscle strength/endurance - abdominal endurance test (sit -up) and flexibility - test of sitting and reaching. As a statistical analysis, the paired t-test was used, adopting p≤0.05. A significant increase was observed in the body mass index, waist circumference, waist-to-height ratio and flexibility after the vacation period. However, there were no significant changes in cardiorespiratory fitness and muscle strength/endurance. Furthermore, analyzing boys and girls separately, no differences were found for waist-to-height ratio and only girls showed improvements in muscle strength/endurance. It was concluded that the vacation exposure factor improved the levels of flexibility and increased the variables of body composition, not generating significant changes in cardiorespiratory fitness, while muscle strength/endurance improved only in girls

Impacts of Fire in Social Wasps Community in an Area of Regenerating Brazilian Savanna

Fire is one of the most common natural harassments and it is characterized as an important component of the systems, although little studied regarding the influence of this event in social wasps communities. One month after the end of the collections, the area of Regenerating Brazilian Savanna of the present study undertook a fire in exactly half of the points sampled, which motivated one further year of sampling. The aim of this study was to compare the social wasps fauna collected before and after the fire, indicating a possible impact on their populations. In the first year of collection, before the fire, 21 species (seven genera) were sampled with a total amount of 297 individuals. In the second year, after the fire, 14 species were collected (reduction of 33,33% in richness) and six genera, with an abundance of 153 wasp individuals of Vespidae (loss of 48,48% of individuals). The area 1 in the first year, presented an abundance of 182 individuals (61,27%) and 16 species (76,19%) and the area 2, 115 (38,73%) and 19 species (90,47%). For the area 1 in the second year, 74 individuals (48,36%) and 12 species (85,71%) were captured and for the area 2 there were 79 individuals (51,64%) distributed among nine species (64,28%). However, we did not find significant values for both the abundance and for the richness among the areas and the years of sampling. Nine species were not registered in the second year, although two presented their registration only after the fire