Cleaner Production of Epoxidized Cooking Oil Using A Heterogeneous Catalyst

A cleaner solvent-free process of used cooking oil epoxidation has been developed. The epoxidation reactions were carried out using “in situ”-formed peroxy acid. A variety of ion exchange resins with different cross-linking percentages and particle sizes such as Dowex 50WX2 50-100, Dowex 50WX2 100-200, Dowex 50WX2 200-400, Dowex 50WX4 50-100, Dowex 50WX4 100-200, Dowex 50WX4 200-400, Dowex 50WX8 50-100, Dowex 50WX8 100-200, Dowex 50WX8 200-400 were used in the synthesis as heterogeneous catalysts. No significant effect of the size as well as porosity of the catalysts on the properties of the final products was observed. In order to develop a more economically beneficial process, a much cheaper heterogeneous catalyst—Amberlite IR-120—was used and the properties of the epoxidized oil were compared with the bio-components obtained in the reaction catalyzed by the Dowex resins. The epoxidized waste oils obtained in the experiments were characterized by epoxy values in the range of 0.32–0.35 mol/100 g. To reduce the amount of waste, the reusability of the ion exchange resin in the epoxidation reaction was studied. Ten reactions were carried out using the same catalyst and each synthesis was monitored by determination of epoxy value changes vs. time of the reactions. It was noticed that in the case of the reactions where the catalyst was reused for the third and fourth time the content of oxirane rings was higher by 8 and 6%, respectively, compared to the reaction where the catalyst was used only one time. Such an observation has not been reported so far. The epoxidation process with catalyst recirculation is expected to play an important role in the development of a new approach to the environmentally friendly solvent-free epoxidation process of waste oils.

Влияние природы лигандов на сорбцию ионов меди (II) активированными углями и ионообменными смолами

В статье приведены результаты сравнительных исследований извлечения ионов меди из водных растворов в отсутствии/присутствии ЭДТА и аммиака с использованием активированного угля NWC и синтетической ионообменной смолы Dowex 50wx8. Рассмотрены кинетические и термодинамические особенности сорбционного процесса. Установлено хорошее соответствие экспериментальных результатов и модели псевдовторого порядка. Для математического описания статического равновесия в процессе сорбции были использованы модели Ленгмюра и Фрейндлиха. Показано влияние природы лигандов на емкость сорбентов и кинетику сорбции ионов Cu(II) из модельных растворов.

Выделение пептидов из ткани головного мозга телят и оценка их тканеспецифической и стимулирующей активности

Разработан метод выделения смеси пептидов из головного мозга телят экстрагированием водным раствором уксусной кислоты с последующим фракционированием экстракта тангенциальной микрофильтрацией и твёрдофазной экстракцией. Выделенная смесь пептидов содержит компоненты с молекулярными массами от 0,1 до 3 кДа. Из этой смеси методом ионообменной хроматографии низкого давления на сульфокатионите Dowex 50WX8 выделен индивидуальный пептид, состоящий из 5 аминокислот: Arg, Lys, Gly, Ser, Leu. Биологическую активность полученного пентапептида оценивали в органотипической культуре эксплантатов мозга крыс линии «Вистар». Показано, что пептид проявляет выраженную тканеспецифическую и стимулирующую активность по отношению к эксплантатам мозга, превышающую активность коммерческих препаратов кортексин и церебролизин.

Optimization of Esterification of Propionic Acid with Ethanol Catalyzed by Solid Acid Catalysts using Response Surface Methodology (RSM): A Kinetic Approach

The esterification of propionic acid and ethanol using waste material as catalyst is emerging and a new technology. In this section a carbon based solid acid catalyst was prepared in laboratory by sulfonating waste rice husk char using concentrated H2SO4 and was compared with a commercial catalyst Dowex 50Wx8-400. Characterization analysis of the catalyst was performed using scaning electron microscope (SEM), EDEX and FTIR. Various reaction parameters such as effect of temperature, effect of the molar ratio of ethanol to propionic acid and effect of catalyst loading were investigated. Reusability of catalyst was also performed 4 cycles for efficiency of prepared catalyst. The activation energy (Ea) of esterification was found to be 39.782 kJ mol−1 using rice husk catalyst and 65.306 kJ mol–1 for Dowex 50wx8-400 catalyst. Response surface methodology (RSM) was applied to find the optimal operating conditions in order to maximize the ethyl propionate conversion.

ESTUDO DA SEPARAÇÃO DO PAR ZIRCÔNIO E HÁFNIO POR TROCA IÔNICA

O zircônio e o háfnio são dois importantes metais para a indústria nuclear. O háfnio ocorrer em todos os minérios de zircônio na faixa de 2 - 3%. Entretanto, o uso do zircônio na indústria nuclear exige que o háfnio esteja em concentrações menores que 100 mg Kg-1. O atual trabalho consiste na separação do par zircônio e háfnio pelo método de troca iônica a fim de se obter um concentrado de zircônio de alta pureza. Os licores de zircônio e háfnio foram produzidos a partir da lixiviação de seus hidróxidos Zr(OH)4 e Hf(OH)4 em meio nítrico por 24 horas. A partir destes dois licores foi preparada uma solução contendo 7,5x10-2 mol L-1 de Zr e 5,8x10-3 mol L-1 de Hf, acidez de 1 M. Os experimentos de troca iônica foram realizados em batelada, com as resinas Dowex 50WX4 50, Dowex 50WX8 100, Dowex 50WX8 50, Amberlite IR-120 e Marathon C a temperatura constante de 28°C. As demais variáveis tais como acidez e agitação foram mantidas constantes. A partir do ajuste dos dados a equação de Langmuir foram calculados o carregamento máximo (qmax), o coeficiente de distribuição (Kd) para o Zr e Hf e o fator de separação. Os resultados de qmax de Zr e Hf, em mmol g-1, mostraram que as resinas mais apropriadas para a remoção em colunas são: Dowex 50WX4 50 (qmax Zr= 2,21, Hf = 0,18), Dowex 50WX8 50 (qmax Zr= 1,89, Hf = 0,13) e Amberlite (qmax Zr = 1,64, Hf = 0,12). A seletividade das resinas para Zr e Hf foi estudada a partir dos fatores de separação que demonstraram que as resinas praticamente não apresentam seletividade. Ensaios de eluição seletiva serão conduzidos visando a separação do par iônico.