Use of Candida rugosa lipase immobilized on sepabeads for the amyl caprylate synthesis: Batch and fluidized bed reactor study

Lipase from Candida rugosa was covalently immobilized on Sepabeads EC-EP for application for amyl caprylate synthesis in an organic solvent system. Several solvents were tested in terms of biocatalyst stability and the best result was obtained with isooctane. The lipase-catalyzed esterification in the selected system was performed in batch and fluidized bed reactor systems. The influence of several important reaction parameters including temperature, initial water content, enzyme loading, acid/alcohol molar ratio, and time of addition of molecular sieves is carefully analyzed by means of an experimental design. Almost complete conversion (> 99%) of the substrate to ester could be performed in a batch reactor system, using lipase loading as low as 37 mg g-1 dry support and in a relatively short time (24 hrs) at 37\ub0C, when high initial substrate molar ratio of 2.2 is used. Kinetics in a fluidized bed reactor system seems to still have a slightly better profile than in the batch system (90.2% yields after 14 hrs). The fluidized bed reactor operated for up 70 hrs almost with no loss in productivity, implying that the proposed process and the immobilized system could provide a promising approach for the amyl caprylate synthesis at the industrial scale

Characterization and radionuclides contents of diatomaceous earth from Kolubara mining basin, Serbia

Diatomaceous earth is of sedimentary origin consists mainly of accumulated skeletons formed as a protective covering of the diatoms. Usually, high absorption capacity of diatomaceous earth provides its wide use as heat insulation, filter and absorbent material. Starting raw material diatomaceous earth from surface coal mine Kolubara, Serbia, was characterized using, scanning electron microscopy (SEM), X-ray diffraction (XRD). Chemical composition of diatomaceous earth was determined by wet chemical methods. In addition, the absorbed gamma ray dose rates is estimated based on the measured activity concentrations of natural radionuclides in clay were determined by gamma spectrometry. This research shows that this material is environmentally safe for further use

Composition and natural radionuclides in clay from Kolubara mining basin, Serbia

The mining basin Kolubara lies about 50 km southwest of Belgrade and stretches across the river Kolubara from Lajkovac to its mouth in the Sava River. During coal exploitation a huge amount of clay is deposited as separate layer. Clay as a raw mineral material has a high economic potential due to their low price and high abundance. This material is used for various applications such as filters, heat insulators, absorbents, catalyst supports, building materialn and advanced environmental applications. Clay from Kolubara mining basin is caracterised by inductively coupled plasma spectroscopy (ICP), X-ray diffraction (XRD), Scanning electron microscopy (SEM). Also, activity concentrations of 40K, 226Ra and 232Th in clay from Kolubara mining, were determined by gamma ray spectrometry with HP Ge detector

Characterization of clay from Kolubara mining basin, Serbia

During coal exploitation in the Kolubara mining basin, Serbia, clay is deposited as accompanying mineral. The aim of the present study is to analyze the activity concentrations of terrestrial (226Ra, 232Th and 40K) and anthropogenic (137Cs) radionuclides in clay collected from Kolubara mining using the high resolution gamma spectrometer with HPGe detector and evaluate external ionizing radiation exposure in outdoor air. The total absorbed gamma dose was in the range of 39-44 nGy/h. In addition, inductively coupled plasma spectroscopy (ICP), X-ray diffraction (XRD), X-ray fluoroscence (XRF), Scanning electron microscopy (SEM) clay from Kolubara mining basin, Serbia, were used. Also, this study is indicative that clay from Kolubara mining is not a significant source of radiation and is suitable for potential use clay in advanced environmental protection area

Characterization of diatomaceous earth from Kolubara mining basin, Serbia

Diatomaceous earth is of sedimentary origin consists mainly of accumulated skeletons formed as a protective covering of the diatoms. Usually, high absorption capacity of diatomaceous earth provides its wide use as heat insulation, filter, and absorbent material. Starting raw material, diatomaceous earth from surface coal mine Kolubara, Serbia, was characterized using X-ray fluoroscence (XRF), X-ray diffraction (XRD), scanning electron microscopy (SEM) were employed to the phases and microstructure of the diatomaceous earth. In addition, concentrations of activity of natural radionuclides 40K, 226Ra and 232Th and anthropogenic radionuclide 137Cs in diatomaceous earth were determined by gamma spectrometry with HPGe detector. It was found that the activity concentrations were in the range of 150-190 Bq / kg for 40K, 5-12 Bq / kg for 226Ra and 22-33 Bk / kg for 232Th. In all samples, the concentration of anthropogenic radionuclide 137Cs was below the detection limit. This research shows that this material is environmentally safe for further use

Characterization of clay mineral from Kolubara mining basin, Serbia, with a determined layered structure

The clay minerals deposit from the mining basin Kolubara, Serbia, is a natural sediment material with high economic potential in many fields. The chemical composition of starting clay determined by inductively coupled plasma spectrometry shows that its main composition of SiO2 is 88.00 wt.%. Organic impurities from clay have been removed by heat treatment at 600 °C for 2 h in air. After thermal treatment, an aqueous solution of HCl sedimentary mineral was chemically treated. Surface properties of starting clay and thermally and chemically treated clay (treated clay) were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and particle size distribution method. The XRD analyses of the starting and treated clay confirmed that quartz is a significant phase, followed by the appearance of feldspar and smectite clays. The SEM method showed impressively layered microstructure on various magnifications for both groups of investigated materials. The average particle diameter value for starting clay was about 23 μm and about 53 μm for treated clay. These methods showed that the starting clay changed the surface properties during thermal and chemical treatment, resulting in the merging of clay layers

Synthesis of spherical SBA-15 silica particles without the use of additional cosurfactant

The synthesis of SBA-15 material with spherical particles is performed by the template method by using only a surfactant Pluronic P123 under acidic conditions. In the synthesis of SBA-15 with spherical particles, an HCl solution was used after specialised chemical treatment of clay purification. The dominant presence of the spheres with diameters up to around 2 μm was confirmed by the scanning electron microscopy(SEM) method. In contrast, the Energy-dispersive X-ray spectroscopy(EDS) confirmed that the spheres consisted only of SiO2 in composition. In addition to the methods mentioned above, X-ray diffraction (XRD), and Fourier-transform infrared spectroscopy(FTIR) methods were used to characterise SBA-15 materials. Application of HCl solution after chemical treatment of clay purification represents the application of technology in the synthesis of spherical SBA-15

The influence of hydrochloric acid on the features of SBA-15 particles

The template method synthesis of both SBA-15 materials with elongated and spherical particles was performed using a surfactant Pluronic P123. The HCl (p.a.) was used to synthesize material with elongated particles connected in chain structures grouped into shapes resembling sheaves of wheat. In the synthesis of spherical SBA-15 with diameters ranging from 0.5 to 2 μm, a spent HCl solution which was obtained after chemical treatment of clay was used where the dominant presence of the spheres was confirmed by the SEM method. In addition to the methods mentioned above, XRD, EDS and FTIR methods characterize SBA-15 materials

Use of Candida rugosa lipase immobilized on sepabeads for the amyl caprylate synthesis: Batch and fluidized bed reactor study

Lipase from Candida rugosa was covalently immobilized on Sepabeads EC-EP for application for amyl caprylate synthesis in an organic solvent system. Several solvents were tested in terms of biocatalyst stability and the best result was obtained with isooctane. The lipase-catalyzed esterification in the selected system was performed in batch and fluidized bed reactor systems. The influence of several important reaction parameters including temperature, initial water content, enzyme loading, acid/alcohol molar ratio, and time of addition of molecular sieves is carefully analyzed by means of an experimental design. Almost complete conversion (> 99%) of the substrate to ester could be performed in a batch reactor system, using lipase loading as low as 37 mg g-1 dry support and in a relatively short time (24 hrs) at 37°C, when high initial substrate molar ratio of 2.2 is used. Kinetics in a fluidized bed reactor system seems to still have a slightly better profile than in the batch system (90.2% yields after 14 hrs). The fluidized bed reactor operated for up 70 hrs almost with no loss in productivity, implying that the proposed process and the immobilized system could provide a promising approach for the amyl caprylate synthesis at the industrial scale