Characterization of the piau fish (Leporinus elongatus) scales and their application to remove Cu(II) from aqueous solutions

Characterization of fish scales of Leporinus elongatus and their application in the removal of Cu(II) from aqueous solutions are described. It was observed that the scales are mainly formed by hydroxyapatite and type I collagen. Adsorption of Cu(II) was performed using batch experiments at 25 0C. The ANOVA statistical results have shown that the Langmuir model was successful applied to determine the maximum adsorption capacity of 2.686 x10-4 mol g-1 and the Langmuir equilibrium parameter (b) of 168.8 L mol-1. The Langmuir separation parameter, RL, has shown favorable adsorption of Cu(II) on the scales

The interaction of a naturally occurring membranous collagen with high-saline dye solutions – mechanistic features from unusual multi-step biosorption

It is known that wastewaters containing dyes are very difficult to treat, since many dyes are stable and recalcitrantmolecules. In this way, sorption may suitable for effectively remove dyes in this specific application field.In this work, a first approach for using polymeric membranous collagen of fish scales for sorption of salinemethylene blue dye (MB) solution found in subsurface procedures of oil well industry. From structural characterization,the sorbent was found to be a composite of fibrillar type I collagen and apatites. The MB sorptionamounts decreased with temperature increasing, with maximum MB sorbed of 2.18 mmol g-1 at 25 0C. In mostsorption tests, residual MB in saline water was undetectable within 200 min of contact time. The sorption kineticdata were well adjusted to a three-parameter multi-step exponential function. The good fitting of such functionwere only obtained taking into account the presence of time-dependent kinetic parameters. The proposed multistepsorption mechanism involved surface interaction and diffusion of MB into the membranous collagen. Theinteraction of positively charged MB ions with the collagenous adsorbent occurred through electrostatic forces.The results point out the collagenous adsorbent for effective procedures of sorption of MB dyes from high-salinewastewaters.Keywords: Biosorption; membranous adsorbents; high-saline water; multi-step kinetics; oil well

Factorial design evaluation of some experimental factors for phenols oxidation using crude extracts form jackfruit (Artocarpus integrifolia)

Este estudo apresenta algumas informações adicionais sobre a utilização alternativa do extrato bruto da jaca, em reações de oxidação seletivas de fenóis. Foram avaliados os substratos catecol, o-, m- e p- cresóis e pirogalol. Estudaram-se também os efeitos do pH, da concentração do tampão fosfato, bem como a utilização de alguns tipos de agentes extratores de biofenóis. Utilizando-se o procedimento convencional univariado, a atividade enzimática foi maior com o substrato catecol, em tampão fosfato pH 5,0, de concentração 0,10 mol L-1 e agente comercial extrator de fenóis Polyclar SB-100â. Usando-se um planejamento fatorial, do tipo 23, constatou-se que os melhores desempenhos catalíticos foram em pH 5,0 e concentração de tampão 0,050 mol L-1, para o substrato catecol. A variação no tipo de extrator não mostrou importância estatística. Pelo método multivariado, obtiveram-se os melhores resultados para a oxidação seletiva do catecol. Assim, conclui-se que para aumentar o desempenho catalítico do extrato, deve-se utilizar preferencialmente a metodologia multivariada. _________________________________________________________________________________________ ABSTRACT:This study presents some additional information on the alternative utilization of Jackfruit crude extracts in selective phenol oxidation reactions, using catechol and the o-, m- e p- cresols and pyrogallol substracts. The effects of pH, concentration of phosphate buffer and kinds of natural phenol extractors are evaluated. By using the conventional univariate procedure, the best enzymatic activities were obtained with the catechol substract, phosphate buffer (pH 5.0) at a concentration 0.10 mol L-1, and the commercial polymer Polyclar SB-100â as natural phenol extractor. Using a full 23 factorial design the best catalytic results were obtained by employing phosphate buffer at pH 5.0 and it 0.050 mol L-1. However, the kind of phenol extractor was not statistically important. The best results for selective catechol oxidation were obtained by using the multivariate technique. In this way, the multivariate methodology is indicated to increase the performance of the crude extract in the selective oxidation reactions

Chemical modification of in natura collagen by acidic catalysis – structural characterization and mechanistic features of Cd(II) sorption by solution microcalorimetry

Chemically-modified in natura collage was prepared under acidic catalysis for using in sorption of Cd(II)from aqueous solutions. Simultaneous determination of the quantity and energetic parameters of Cd(II) sorptionon PGA-scale at pH 8.0 were determined using solution microcalorimetry (SM). The calorimetric enthalpiesof Cd(II) sorption on PGA-scale are all exothermic, and Cd(II) adsorption energies decrease as temperatureincreases. The maximum sorption capacity of PGA-scale for Cd(II) (438 μmol g-1) is superior withmany sorption data reported in the literature. Characterization and SM indicate that the main sites for Cd(II)sorption are located in the collagen structure of PGA-scale. It was found that the interactions PGAscale/Cd(II) are mainly due to chemisorption and diffusion may occur at the PGA-scale/Cd(II) interface. Theresults of this study underline the good features of PGA-scale as a promising material for sorption of Cd(II)from aqueous media.Keywords: Cadmium; biosorbents; fish scales; acidic catalysis; solution microcalorimetry; thermodynamics

Estudo termoquimico das interações de ions metalicos e aminas primarias com silica gel funcionalizada

Orientador: Jose de Alencar SimoniTese (doutorado) - Universidade Estadual de Campinas, Instituto de QuimicaResumo: Sílica gel (Fluka) teve sua superfície funcionalizada com o organossilano (CH3O)3Si(CH2)3SH. O material obtido (Sil-SH) mostrou, em trabalhos anteriores, a capacidade de extrair alguns cátions metálicos de soluções aquosas e etanólicas. No intuito de se estabelecer uma sistemática para o mapeamento dos sítios básicos criados com a funcionalização, foram determinadas variações de energia que ocorrem nas interações entre o organossilano imobilizado e os cátions Ag(I), Hg(II), Cu(II), Ni(lI) e Zn(II). Pelo fato de que a Sil-SH contendo os cátions metálicos (Sil-SM) apresenta como característica a presença de sítios ácidos, estudou-se também a interação deste novo material com algumas aminas RNH2 (R = CH3, C2H5 , C3H7 e C4H9), cuja meta foi também o mapeamento destes novos sítios criados. As variações de energia para todos os processos estudados foram obtidas pela técnica de titulação calorimétrica. Os efeitos térmicos decorrentes da interação e também quantidades de cátions e aminas que interagem em cada ponto da titulação foram determinados simultaneamente. A partir deste procedimento, valores de N (capacidade máxima de interação), Qmon (energia integral de interação) e DmonHm (entalpia integral de interação para a formação de uma monocamada) foram obtidos. A energia de interação entre os sítios básicos do organossilano e os cátions metálicos, conforme indicada pelos valores de DmonHm (kJ mol), estão na seqüência: Cu (-80,12 ± 1,09) > Ag (-59,01 ± 0,82) > Hg (-51,14 ± 0,72) > Ni (-32,02 ± 0,49) > Zn (27,14 ± 0,41) em meio aquoso e Cu (-106,47 ± 1,54) > Hg (-37,68 ± 0,54) > Ag (-26,18 ± 0,37) > Zn (-21,93 ± 0,32) em meio etanólico. Para os processos de interação entre as aminas e a SiI-SHg, os valores de DmonHm (kJ mol) seguem a mesma ordem das constantes de basicidade das aminas: SiI-SHg/C2H5NH2 (-44,16 ± 0,68) > SiI-SHg/C4H9NH2 (-30,49 ± 0,43) > Sil-SHg/CH3NH2 (-27,83 ± 0,42) > SiI-SHg/C3H7NH2 (-25,37 ± 0,46) A etilamina foi escolhida como referência para se avaliar a acidez relativa dos cátions metálicos na SiI-SM. Os valores de DmonHm (kJ mol) na seqüência: Zn/C2H5NH2 (-107,46 ± 1,39) > Ni/C2H5NH2 (-75,43 ± 1,01) > Cu/C2H5NH2 (-62,46 ± 0,93) > Hg/C2H5NH2 (-44,16 ± 0,68) > Ag/C2H5NH2 (-28,52 ± 0,40), mostram que o caráter duro-mole parece ser o fator predominante no processo de interação.Abstract: Sílica gel (Fluka) had its surface functionalized with the organosilane (CH3O)3Si(CH2)3SH. The material obtained (SiI-SH) has shown, in previous studies, the capacity of extracting some metallic cations from aqueous and ethanolic solutions. With the purpose of establishing a method to chart the basic sites criated with the functionalization, energy variations that occur in the interactions between the immobilized organosilane and Ag(l), Hg(II), Cu(II), Ni(lI) e Zn(II) cations were determined. Because the SiI-SH with the metallic cations (SiI-SM) also has as a characteristic the presence of acid sites, the interaction of this new material with some amines RNH2 (R = CH3 , C2H5 , C3H7 e C4H9), was studied with the objective whose of charting these newly created sites. The variations of energy for all the processes studied were obtained by the titration calorimetric technique, in which thermic effects as well as quantities of cations and amines that interact in each titration point were determined simultaneously. From this procedure, values of N (maximum capacity of interaction), Qmon (integral energy of interaction) and DmonHm (molar integral entalpy of interaction for a monolayer) were obtained. The interaction energy between the basic sites of the organosilane and the metallic cations, as indicated by DmonHm (kJ mol), are in the sequence: Cu (-80,12 ± 1,09) > Ag (-59,01 ± 0,82) > Hg (-51,14 ± 0,72) > Ni (-32,02 ± 0,49) > Zn (27,14 ± 0,41) in an aqueous medium and Cu (-106,47 ± 1,54) > Hg (-37,68 ± 0,54) > Ag (-26,18 ± 0,37) > Zn (-21,93 ± 0,32) in the ethanolic medium. For the interaction processes between the amines and SiI-SHg, the DmonHm (kJ mol) values follow the same order of the basicity constants of the arnines: SiI-SHg/C2H5NH2 (-44,16 ± 0,68) > SiI-SHg/C4H9NH2 (-30,49 ± 0,43) > SiI-SHg/CH3NH2 (-27,83 ± 0,42) > SiI-SHg/C3H7NH2 (-25,37 ± 0,46) Ethylamine was choosen as a reference base in order to evaluate the relative acidity of the metallic cations in the SiI-SM. The DmonHm in the sequence Zn/C2H5NH2 (-107,46 ± 1,39) > Ni/C2H5NH2 (-75,43 ± 1,01) > Cu/C2H5NH2 (-62,46 ± 0,93) > Hg/C2H5NH2 (-44,16 ± 0,68) > Ag/C2H5NH2 (-28,52 ± 0,40), show that, apparently, there is predominance of the hard-soft character in the interaction process.Doutorad