Orientadores: Meuris Gurgel Carlos da Silva, Sirlei Jaiana Kleinübing / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-21T03:51:16Z (GMT). No. of bitstreams: 1 Santana_HarrsonSilva_M.pdf: 3086288 bytes, checksum: df57d56b5e16a94632301ad2849fb91b (MD5) Previous issue date: 2012 / Resumo: Este trabalho teve como objetivo avaliar a bioadsorção dos íons Cd2+, Cu2+, Pb2+, Ni2+ e Zn2+ pela macrófita aquática Limnobium spongia em sistema estático. Diagramas de especiação em função do pH, foram simulados usando o software HYDRA, de modo a se conhecer as diferentes espécies em meio aquoso, nas condições estudadas. Observa-se que em pH<5,0 não ocorre precipitação para todos os íons estudados. A técnica de Espectroscopia na Região do Infravermelho (FTIR) foi utilizada para identificação dos grupos funcionais presentes no bioadsorvente, que poderiam estar envolvidos no processo de bioadsorção. Observou-se que os grupos aminos, amidas e ácidos carboxílicos participam do processo de bioadsorção dos íons metálicos estudados. Para análise da superfície do bioadsorvente nas diferentes condições estudadas foi utilizada a Microscopia Eletrônica de Varredura (MEV). A técnica de EDX (Espectroscopia de Raios X por Energia Dispersiva) acoplada a MEV foi utilizada para caracterizar as espécies naturalmente presentes na macrófita e fazer um mapeamento da distribuição das diferentes espécies metálicas bioadsorvidas. Verificou-se grande quantidade de íons Mg2+, Na2+, Al3+, e Ca2+, naturalmente presentes na macrófita e redução destes íons após a bioadsorção dos íons metálicos estudados, indicando que o mecanismo de troca iônica pode estar ocorrendo. Modificações químicas da biomassa foram efetuadas a fim de aumentar a sua capacidade de bioadsorção. O tratamento com NaOH (0,1M) provocou uma elevação na capacidade de remoção de 35, 20, 10, 11 e 15% para os íons Cd2+, Cu2+, Pb2+, Ni2+ e Zn2+, respectivamente. Foi realizado um estudo estático (cinético e de equilíbrio) da bioadsorção das diferentes espécies metálicas pela macrófita L. spongia nas temperaturas de 20, 30 e 40 ºC. Pelo estudo cinético observa-se que nos primeiros 90 minutos o sistema macrófita/íon metálico entra em equilíbrio para todas as espécies estudadas. As quantidades máximas adsorvidas, de acordo com o modelo de Langmuir foram de 0,65; 1,29; 0,69 e 0,83 mmol g-1, para os íons Cd2+, Pb2+, Ni2+ e Zn2+, respectivamente, na temperatura de 40 °C e 0,83 mmol g-1 para o Cu2+ na temperatura de 20 °C. Diferentes soluções eluentes foram testadas na dessorção dos diferentes íons metálicos. Foram estudados, ainda, três ciclos de bioadsorção/dessorção, sendo verificado que a macrófita manteve suas características de bioadsorção / Abstract: This study had the objective of evaluating the bioadsorption of Cd2+, Cu2+, Pb2+, Ni2+ and Zn2+ by macrophyte Limnobium spongia in static system. Speciation diagrams as a function of pH were simulated using the software HYDRA, in order to know the various species in the aqueous solutions under the conditions studied. It is observed that at pH <5.0, precipitation does not occur for all ions studied. The Fourier transform infrared spectroscopy (FTIR) technique was used to identify the functional groups presented in biosorbent, which could be involved in the bioadsorption process. In order to analyze the biosorbent surface in different conditions, the Scanning Electron Microscopy (SEM) was used. The EDX (Energy Dispersive Spectroscopy X ray) technique coupled with SEM was used to characterize the own species of macrophytes and to map the distribution of the various metal species on the bioadsorbent surface. There was a large amount of Mg2+, Na2+, Al3+, and Ca2+ ions naturally presented in the macrophyte and the reduction of these ions after bioadsorption, indicating that the ion exchange mechanism may be occurring. Biomass chemical modifications were performed in order to increase by bioadsorption capacity. The treatment with NaOH (0.1 M) caused an increase in the removal capacity of 35, 20, 10, 11 and 15% for Cd2+, Cu2+, Pb2+, Ni2+ and Zn2+, respectively. A bioadsorption static study was conducted (kinetic and equilibrium) of different metal species by macrophyte at temperatures of 20, 30 and 40 ºC. The kinetic study shows that in 90 minutes the system macrophyte / metal ion comes into equilibrium for all species. The maximum bioadsorbed amounts, according to the Langmuir model, were 0.65, 1.29, 0.69 and 0.83 mmol g-1 for Cd2+, Pb2+, Ni2+ and Zn2+, respectively, at a temperature of 40 ºC and 0.83 mmol g-1 for Cu2+ at 20ºC. Different eluents were tested in solutions of different metal ions desorption. Furthermore, the study of three biosorption/desorption cycles were made and it was verified that the macrophyte kept their biosorption characteristics / Mestrado / Engenharia de Processos / Mestre em Engenharia Química

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The objective of this work is development of a new adsorbent on the base of an organoclay with a chelating ligand covalently attached to the clay mineral surface. The presence of a chelating ligand in the clay structure significantly improves its ability to immobilize heavy metal ions from contaminated sludge of wastewater. Montmorillonite and kaolinite were chosen as typical examples of expandable and non-expandable clay minerals. A two-step modification procedure comprised of sequential modification with oxides and grafting of a chelating agent to the modified clay minerals was used. Modifications with silica and ferric oxide were conducted by reacting the dispersed raw clay minerals with tetraethoxysilane and ferric nitrate solution. A chelating ligand, N-[3-(trimethoxysilyl)propyl]ethylenediamine triacetic acid trisodium salt, was introduced into interlayer space of raw and modified clay minerals in aqueous solutions. Laboratory tests of the organoclay efficiency for purification of wastewater were conducted with the most promising sample, i.e., organoclay with the highest specific loading of chelating agent. Experiments were conducted with model wastewater containing either individual or mixed heavy metal ions. The modified organoclay displayed high adsorption capacity for heavy metal cations even in acidic media. The method of modification presented in this work can be used for synthesis of efficient adsorbents for applications in contaminated areas.

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Research on heavy metal music has traditionally been framed by deviant characterizations, effects on audiences, and the validity of criticism. More recently, studies have neglected content analysis due to perceived homogeneity in themes, despite evidence that the modern genre is distinct from its past. As lyrical patterns are strong markers of genre, this study attempts to characterize heavy metal in the 21st century by analyzing lyrics for specific themes and perspectives. Citing evidence that the “Millennial” generation confers significant developments to popular culture, the contemporary genre is termed “Millennial heavy metal” throughout, and the study is framed accordingly. Utilizing prominent metal albums from the 2000-2009 decade, 250 randomly selected songs are analyzed for the inclusion of 115 different themes and their contextual usage. The frequency of each theme is then ranked by prevalence in order to illustrate common focus in the genre. Results showed that themes of death, storytelling, violence, and social commentary prevail; overall, accentuated topics and their usage point to an aptitude for confronting tenebrous realities and personal attempts to understand them. Characteristic connections between Millennial metal and the Millennial generation are also noted through emphasized individuality, social awareness, and civil liberalism

Heavy metal (HM) containing quantum dots (Qdots) are increasingly used in commercial products due to their unique electronic, optoelectronic, optical and magnetic properties. Once disposed to the landfill, environmental weathering is likely to compromise HM Qdot integrity, leading to release of heavy metal ions. To minimize any negative environmental impact of HM Qdots, there is an increasing demand for developing HM free or environmentally-friendly surface modified HM Qdot alternatives. In this study, synthesis of HM free ZnS:Mn/ZnS and surface modified HM CdS:Mn/ZnS Qdots (using N-acetylcysteine, NAC, and Dihydrolipoic acid, DHLA) and their potential toxicity assessment using E. coli as a model system is reported. NAC and DHLA are known antioxidants and therefore expected to reduce HM induced toxicity and improve colloidal stability of Qdots. All Qdots were synthesized at room temperature using a reverse micelle microemulsion method. Qdots were fully characterized using UV-visible absorption spectroscopy, fluorescence emission spectroscopy, zeta potential, Nuclear Magnetic Resonance spectroscopy (NMR) and High Resolution Transmission Electron Microscopy (HRTEM). Qdot environmental weathering was simulated by treating Qdots with concentrated acid (6N HCl). Qdot toxicity was evaluated on E. coli growth and viability using growth curves, turbidity and bactericidal assays (CFU). Results show that Zn based Qdots exhibit reduced toxicity on E.coli growth and viability when compared to Cd based Qdots. In addition, surface modification with NAC and DHLA minimized toxicity of Cd based Qdots. In summary, Zn based Qdots appear to be more environmental-friendly than Cd based Qdots

Wastewater contaminated with heavy metal ions (HMIs), stemming from human activities and natural disasters, poses substantial threats to both the environment and human health. The unchecked release of untreated wastewater into natural water bodies leads to severe pollution, upsetting ecological balance. To address this pressing challenge, microalgae-based biosorption technology has emerged as a promising solution for the efficient removal of HMIs from wastewater. Microalgae, with their extensive surface area and intricate cell wall structures, exhibit remarkable efficacy in HMIs biosorption. This thesis aims at elucidating the fundamental principles governing the interactions between HMI and microalgal cells to help enhance the biosorption capacity of HMI by microalgae from two perspectives: 1) conditioning of biomass by either optimizing the cultivation conditions or downstream processing; and 2) conditioning of the biosorption process for optimal performance of given algal biomass. It was demonstrated that among the tested cultivation conditions, i.e., culture pH, phosphate concentration, nitrate concentration, and dissolved inorganic carbon (DIC) conditions, which all have significant impacts on cell surface structure and therefore biosorption of HMI, DIC is the most significant factor. Furthermore, it was demonstrated that downstream processing of biomass such as lipid extraction with sonication for cell disruption could help enhance specific surface area and removal of lipids from cell wall surfaces, resulting in remarkably elevated HMI biosorption capacities. As for research on biosorption mechanisms, a correlation between HMI properties, i.e., ionic radius and electronegativity, and their biosorption capacities onto certain microalgal biomass, was established, which was validated with both experimental data and literature data. Furthermore, systematic studies on biosorption kinetics, isotherm, and thermodynamics, as well as cell surface characterization, and determination of HMI intracellular and extracellular contents of cells after biosorption were carried out, which converged on the conclusion that biosorption was predominantly monolayer surface adsorption. A mathematical model was proposed and validated, which is a rigid model accounting for the effects of cell size and HMI radius only. Analysis of model differentiation from experimental data led to the hypothesis that the nanostructures on cells, mostly like pili, were the major locations where binding sites for HMI were housed. This research represents a significant step towards ensuring the responsible and sustainable use of microalgae for environmental engineering, promising a cleaner and healthier future.

When heavy metal fans traverse through their everyday life, they are faced with countless opportunities to engage in social interactions with others. Such interactions question, establish, and strengthen fans’ heavy metal identities whilst providing them with a sense of community and belonging through engaging with others who also share a preference for heavy metal music. This thesis is built on a qualitative research approach, complimented by an insider and ethnographic orientation in order to explore identity expression, the feeling of belonging and community, everyday life processes, and the role of heavy metal music in the everyday life of heavy metal fans. Through social interactions based on shared musical preference, heavy metal fans are able to meaningfully engage with others through which communal affiliations are strengthened and reinforced. Despite mainstream, and largely negative attitudes towards heavy metal, the music provides a safety net for listeners and is a driving force in their experience of the reciprocal relationship between personal identity and group membership and community. Due to the deep connection listeners have with heavy metal, the music becomes something which fans are able to call theirs alone.

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