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The high free fatty acids content in some vegetable oils can have a negative impact in the sustainable production of biodiesel. The previous treatment of these feedstock oils can contribute to the reduction of the process total costs as well as the environment, turning the biodiesel a more competitive in relation to the fossil diesel. The aim of this work was to adequate low cost vegetable oils to the production of biodiesel by homogeneous catalysis. The feedstock was evaluated by its acidity, by its free fatty acids content, by its saponification index and its specific mass. The Biodiesel produced was characterized by high performance liquid chromatography. The results showed significant free fatty acids and humidity content, which are the main factors in the raising of the production costs. The results also showed that the esterification of the vegetable oils reduced its acidity in about 99%. The transesterification of the Brazilian nut oil previously esterified yields about 98% of biodiesel. Even though the biodiesel processing presents an alternative to the energetic self-sufficiency of Brazil, there are many challenges in the adequacy of these high acidity oils and fats for its production.

The chemical and mineralogical properties of phlogopitite, a rock containing the mineral phlogopite, were studied aiming at employment as an alternative source of potassium. Mineralogical characterization of this rock was performed using X-ray diffractometry, X-ray fluorescence, scanning electron microscopy and infrared spectroscopy. According to the results, phlogopite contains approximately 82.6 g K2O kg-1 (ca. 9%). The kinetics involved in the release of the potassium ions from the mineral were examined using acidic solutions (nitric, citric, oxalic and Mehlich-1) and a salt solution (sodium tetraphenylboron, Na[B(C6H5)4]). The experimental results from the kinetic studies were used to determine the mathematical relationship between the concentration of potassium released and the reaction time. As propriedades químicas e mineralógicas do flogopitito, uma rocha que contém flogopita, foram estudadas tendo em vista o emprego como fonte alternativa de potássio. A caracterização mineralógica da rocha foi realizada por difratometria de raios X, fluorescência de raios X, microscopia eletrônica de varredura e espectroscopia na região do infravermelho. De acordo com os resultados, flogopita contém 82,6 g K2O kg-1 (ca. 9%). A cinética de liberação do íon potássio a partir do mineral foi avaliada em meio ácido (nítrico, cítrico, oxálico e Mehlich-1) e em uma solução salina (tetrafenilborato de sódio, Na[B(C6H5)4]). Os resultados experimentais obtidos a partir dos estudos cinéticos foram ajustados para determinar uma relação matemática entre a concentração de íons potássio liberada em solução e o tempo de liberação.

The synthesis and characterization of silica nanoparticles (NPs) covalently modified with an aminonaphthoquinone are reported. The aminopropylsilicagelnaphthoquinone (APSGNQ) was obtained by nucleophilic substitution of 2-methoxy-1,4-naphthoquinone with aminopropylsilicalgel (APSG) NPs. Solid state 13C and 29Si nuclear magnetic resonance spectra confirmed that the naphthoquinone is covalently bonded to APSG. Due to the solubility of APSGNQ in common organic solvents, solution ultraviolet-visible spectroscopy was used to determine the amount of naphthoquinone on the NPs surface (0.56 mmol of incorporated naphthoquinone per gram of APSGNQ) by comparison with the spectrum of 2-aminobutyl-1,4-naphthoquinone (ABNQ). Elemental analysis indicated that about 8% of the surface propylamine remained unreacted in APSGNQ. These multifunctional silica NPs have potential in medical applications. Nanopartículas de sílica (NPs) modificadas covalentemente com uma aminonaftoquinona foram sintetizadas e caracterizadas. A aminopropilsilicagelnaftoquinona (APSGNQ) foi obtida por substituição nucleofílica do grupo metóxi da 2-metóxi-1,4-naftoquinona por NPs modificadas com o grupo aminopropil (APSG). Os espectros de ressonância magnética nuclear de 13C e 29Si no estado sólido confirmaram que a naftoquinona encontra-se ligada covalentemente à aminopropilsilicagel. Como o composto APSGNQ é solúvel em solventes orgânicos comuns, foi possível quantificar o ancoramento da naftoquinona na superfície das NPs modificadas por espectroscopia no ultravioleta-visível (0,56 mmol de naftoquinona ancorada por grama de APSGNQ), por comparação com o espectro do composto análogo 2-aminobutil-1,4-naftoquinona (ABNQ). Os dados das análises elementares indicaram que aproximadamente 8% da propilamina presente na superfície do composto APSGNQ não reagiu com a metóxinaftoquinona. Essas NPs de sílica multifuncionais têm potencial para aplicações médicas.

Two dendrimers were designed and synthesized that contain a 1,3,5-trisubstituted benzenoid core and incorporate 9 and 21 viologen (4,4′-bipyridinium) units in their branches in addition to hydrophilic (aryloxy) terminal groups. For comparison purposes, model compounds containing one and two viologen units were also studied. These polycationic dendrimers form strong host–guest complexes with the dianionic form of the red dye eosin in dilute CH2Cl2 solutions. Titration experiments, based on fluorescence measurements, showed that each viologen unit in the dendritic structures becomes associated with an eosin dianion. Electrochemical (in MeCN) and photosensitization (in CH2Cl2) experiments revealed that only a fraction of the viologen units present in the dendritic structures can be reduced. This fraction corresponds to the number of viologen units present in the outer shells of the dendrimers. The reasons for incomplete charge pooling are discussed. Comparison with the behavior of polyviologen dendrimers that are terminated with bulky tetraarylmethane groups and were studied previously enabled the role played by the terminal groups in the redox and hosting properties to be elucidated. Sono stati progettati e sintetizzati due dendrimeri contenenti un'unita benzenica sostituita nelle posizioni 1,3,5 come core, 9 e 21 unita viologeno (4,4′-dipiridinio), rispettivamente, nelle ramificazioni e gruppi idrofilici di tipo arilossi come unita periferiche. In CH2Cl2 questi dendrimeri policationici interagiscono con la forma dianionica dell'eosina dando complessi host–guest in cui, come mostrato chiaramente dalle titolazioni basate su misure di fluorescenza, ogni unita viologeno contenuta nella struttura dendritica si associa con un anione eosina. Esperimenti di riduzione elettrochimica (in MeCN) e fotochimica (in CH2Cl2 e in presenza di un opportuno fotosensibilizzatore) hanno inoltre messo in evidenza che non tutte le unita viologeno contenute nei dendrimeri possono essere ridotte; in particolare, sembra che siano riducibili solo quelle presenti nel guscio dendritico piu esterno. Il confronto con il comportamento di composti modello, contenenti una e due unita viologeno, e di dendrimeri precedentemente investigati, che differiscono da quelli discussi in questo lavoro per la presenza di gruppi terminali piu ingombranti di tipo tetraarilmetano, ha fatto luce sui motivi che inibiscono la riduzione di tutte le unita viologeno contenute nelle strutture dendritiche e ha chiarito se e come la natura dei gruppi terminali influenza le proprieta redox e complessanti di questi dendrimeri.