The influence of alcohol:oil molar ratio on the canola oil transesterification reaction in solvent-free medium using free lipase from Thermomyces lanuginosus and Burkholderia cepacia was studied. The experiments conducted in batch reactor for 72 h at 37°C in cosolvent-free reaction system with ethanol addition in three steps showed great potential for ester production. The stepwise addition of ethanol allowed increasing yield throughout the total period of the reaction, even if the course has limited reaction at times, minimizing possible deleterious effects of the alcohol on the enzyme structure. The highest yields were achieved with lipase from T. lanuginosus, despite presenting lower activity values than those of Burkholderia cepacia lipase, which proved to be less selective for ester production. In the reaction medium containing lipase from T. lanuginosus, 100 % yield was obtained using a molar ratio of 12:1. For B. cepacia lipase, the highest yield was 90.73% at a molar ratio of 6:1. In all cases studied, at least 92% of the triacylglycerols from canola oil were consumed.
ABSTRACT:The uptake capacity of Fe(III) ions by NaY zeolite was investigated in this work. Column experiments were undertaken on continuous systems at 30ºC, pH = 3.5, employing a flow rate of 2 mᐉ/min and an average particle size of 0.180 mm. The dynamic system exhibited a distinct ionexchange mechanism which generated a favourable isotherm with an Fe(III) ion uptake of 2.16 mequiv/g. A mathematical model was also applied to represent the dynamics of the sorption process. The dynamic isotherm was successfully modelled by the Langmuir equation while the mathematical model gave a good description of the experimental dynamic data for feed concentrations ranging from 0.2 mequiv/ᐉ to 3.5 mequiv/ᐉ. The ion-exchange kinetics for Fe(III) ions were studied using the first-, second-order and Langmuir kinetic models.
This study was aimed at investigating the equilibrium and interactive effects of binary solutions containing Zn +2 and Fe +3 ions in fixed-bed columns of NaY zeolite. To calculate the dynamic equilibrium through isotherms, experiments were carried out in a fixed-bed column. Reagent-grade ZnCl 2 and FeCl 3 ·6H 2 O solutions were mixed with deionized water to prepare the feed solutions with total ion concentrations in the range of 0.5-5.0 meq/ . Experiments were then carried out using Fe 3+ and Zn 2+ ions in the following concentration ratios: 0.75:0.25, 0.50:0.50 and 0.25:0.75. The experimental equilibrium data were then described using Langmuir-type models (binary Langmuir model, Langmuir-type model, Jain and Snoeyink model, and noncompetitive Langmuir model) as well as ion exchange model. Results of our analysis revealed that NaY zeolite has a higher affinity for Zn 2+ than Fe 3+ ions. The equilibrium data were best fit to the Langmuir-type model. Zn 2+ ions are removed through an ion-exchange process while the Fe 3+ ions may be preferentially adsorbed onto the already exchanged zeolitic sites. This equilibrium model was then applied to a dynamic mathematical model. We describe the equilibrium in this model by assuming the binary Langmuir-type model and mass transfer in the zeolite based on the linear driving force model.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.