Biodiesel production had received a considerable attention as a green, non-toxic and renewable alternative to petroleum diesel. To avoid using vegetable oils, which are expensive and compete with food, as feedstock, w...Biodiesel production had received a considerable attention as a green, non-toxic and renewable alternative to petroleum diesel. To avoid using vegetable oils, which are expensive and compete with food, as feedstock, waste oils have been proposed. However, these waste materials contain a large amount of free fatty acids that complicates the production process. In this work, biodiesel production using an alternative feedstock;namely oils from date-pits, has been investigated. These oils have the same favorable features of straight oils, and at the same time are considered waste, since they are extracted from a waste material. The yield of oils extracted using n-hexane in a Soxhlet apparatus was compared to that of oils extracted using methanol-chloroform solvent mixture. The extracted oils were then converted to biodiesel via transesterification with methanol in presence of Novozym𪥣 or Eversa®Transform. The highest oils extraction yield of 11.7%, per dry weight sample, was obtained using Soxhlet extraction apparatus compared to 8.9% using methanol-chloroform mixture. The highest biodiesel production yield was 30% of the oil used, achieved after 6 hours using Novozym𪥣 at 40°C, 5:1 methanol to oil molar ratio and 10wt% enzyme loading. By using a chemical alkaline catalyst, NaOH, at the same conditions, the yield was 27%.展开更多
Post synthetic modification of a hydrophilic metal-organic framework(MOF),HKUST-1,with stearic acid(SA)was carried out to enhance the stability of HKUST-1 in aqueous solution to be used as a support for formate dehydr...Post synthetic modification of a hydrophilic metal-organic framework(MOF),HKUST-1,with stearic acid(SA)was carried out to enhance the stability of HKUST-1 in aqueous solution to be used as a support for formate dehydrogenase(FDH)used for CO_(2)conversion to formate.SA modification improved the hydrophobicity without affecting the morphology and crystal structure of MOF.Adsorption of FDH on the modified MOF(SA@HKUST-1)was compared to that of the native HKUST-1 and ZIF-L.The adsorption kinetics on all MOFs was found to follow pseudo-second order kinetics and the isotherm was best described by Freundlich model.The high stability of SA@HKUST-1 and enhanced hydrophobic interaction between support and CO_(2)resulted in high catalytic efficiency and stability of FDH@SA@HKUST-1.The immobilized enzyme retained 95.1%of its initial activity after 4 cycles of repeated use.It was also shown that FDH@SA@HKUST-1 retained morphology and crystal structure after repeated use.Results of the present work provide novel insight into the influence of hydrophobic MOFs on the activity and stability of immobilized FDH.These findings are expected to assist in developing highly active and stable biocatalysts for CO_(2)hydrogenation at commercial level.展开更多
文摘Biodiesel production had received a considerable attention as a green, non-toxic and renewable alternative to petroleum diesel. To avoid using vegetable oils, which are expensive and compete with food, as feedstock, waste oils have been proposed. However, these waste materials contain a large amount of free fatty acids that complicates the production process. In this work, biodiesel production using an alternative feedstock;namely oils from date-pits, has been investigated. These oils have the same favorable features of straight oils, and at the same time are considered waste, since they are extracted from a waste material. The yield of oils extracted using n-hexane in a Soxhlet apparatus was compared to that of oils extracted using methanol-chloroform solvent mixture. The extracted oils were then converted to biodiesel via transesterification with methanol in presence of Novozym𪥣 or Eversa®Transform. The highest oils extraction yield of 11.7%, per dry weight sample, was obtained using Soxhlet extraction apparatus compared to 8.9% using methanol-chloroform mixture. The highest biodiesel production yield was 30% of the oil used, achieved after 6 hours using Novozym𪥣 at 40°C, 5:1 methanol to oil molar ratio and 10wt% enzyme loading. By using a chemical alkaline catalyst, NaOH, at the same conditions, the yield was 27%.
基金The authors express their gratitude to Zayed Center of Health Sciences(grant number 31R236)the College of Graduate Studies(PhD fund 31N438)at UAE University,for financially supporting this study.
文摘Post synthetic modification of a hydrophilic metal-organic framework(MOF),HKUST-1,with stearic acid(SA)was carried out to enhance the stability of HKUST-1 in aqueous solution to be used as a support for formate dehydrogenase(FDH)used for CO_(2)conversion to formate.SA modification improved the hydrophobicity without affecting the morphology and crystal structure of MOF.Adsorption of FDH on the modified MOF(SA@HKUST-1)was compared to that of the native HKUST-1 and ZIF-L.The adsorption kinetics on all MOFs was found to follow pseudo-second order kinetics and the isotherm was best described by Freundlich model.The high stability of SA@HKUST-1 and enhanced hydrophobic interaction between support and CO_(2)resulted in high catalytic efficiency and stability of FDH@SA@HKUST-1.The immobilized enzyme retained 95.1%of its initial activity after 4 cycles of repeated use.It was also shown that FDH@SA@HKUST-1 retained morphology and crystal structure after repeated use.Results of the present work provide novel insight into the influence of hydrophobic MOFs on the activity and stability of immobilized FDH.These findings are expected to assist in developing highly active and stable biocatalysts for CO_(2)hydrogenation at commercial level.
