Advances in nanocatalysts design for biofuels production

The exploitation of nanocatalysts, at the boundary between homogeneous and heterogeneous catalysis, is tracking new efficient ways to produce renewable biofuels in environmentally friendly conditions. Their solid state makes them recyclable, and their nanomateric particle size enables high activities approaching those offered by homogeneous catalysts, as well as novel and unique catalytic behaviors not accessible to solids above the nanometer range. Furthermore, the use of magnetically active materials has led to the development of nanocatalysts easily recoverable through the application of magnetic fields. In this mini-review, latest achievements in the production of advanced biofuels using stable, highly active, cheap and reusable nanocatalysts are described. Specifically, biodiesel and high density fuels have been chosen as major topics of research for the design of catalytic nanomaterials

Sunflower oil methanolysis over modified CaO catalysts

Oil methanolysis over modified CaO catalysts was studied to assess the catalytic performance and to define an appropriate kinetic model. CaO was modified by commercial glycerol and a deep eutectic solvent (DES), choline chloride : glycerol (ChCl : Gly), to obtain catalytically active complexes of CaO and glycerol. The main goal was to investigate the effect of the obtained complexes on the reaction rate and fatty acid methyl ester (FAME) content and to describe the variation of the triacylglycerol (TAG) conversion degree during the reaction time. Fourier transform infrared spectroscopy (FTIR) was applied to confirm the formation of CaO complexes with glycerol or the glycerol-based DES. Different catalyst loadings (0.5, 1, and 5 % of oil weight) and methanol-to-oil molar ratios (6 : 1 and 12 : 1) were applied for investigation of the sunflower oil methanolysis at 60 oC. Two kinetic models were employed yielding the kinetic parameters, which depended on the catalyst loading and the methanol-to-oil molar ratio. Both models showed valid applicability for describing the kinetics of the reactions catalyzed by both complexes (the mean relative percent deviation was lower than 10 %).</jats:p

Continuous biodisel productions: A review

Continuous biodiesel production on laboratory and industrial scale was analyzed, with focus on their advantages and disadvantages. Attention was paid to specific characteristics of industrial processes in order to point out the advanced technologies. The well-known base-catalyzed continuous biodiesel production processes are related to problems caused by the immiscibility of the reactants (alcohol and oil), application of relatively high operating temperature (usually the boiling temperature of alcohol or one near it) and obtained yield of methyl ester yields lower than desired. One way to overcome these problems is to employ special reactor design favoring the emulsion process and increasing the overall rate of biodiesel production process, even at room temperature and atmospheric pressure. The second way is to apply heterogeneous catalysts in continuous processes, which will probably be the optimal approach to economically justified and environmentally friendly biodiesel production

Mortality Of Malignant Melanoma In Central Serbia, In The Period 1999-2015

Introduction: Malignant melanoma is one of the rarest but the most deadly form of skin cancer.&#x0D; Objective: The objective of this paper was to analyze the epidemiological characteristics and trends of mortality from malignant melanoma of the population of Central Serbia in the period 1999-2015.&#x0D; Methods:  The study was designed as a retrospective descriptive epidemiological study. Standardized mortality rates were used in statistical data processing.  A linear trend model and regression analysis were used to examine trends in malignant melanoma mortality.&#x0D; Results:  In Serbia, malignant melanoma mortality shows an increasing trend. The overall age-adjusted melanoma death rate was 2.6 per 100 000 with a higher death rate among men (3.03per 100 000) than among women (2.1 per 100 000). Malignant melanoma mortality rates increase with age in both sexes and are highest in the age group of 75 and older. The highest increase in mortality in men is recorded in the age group of 65-69 years, with an average percentage increase of 21.33 (95% CI, 8.40 - 51.05), while in women the largest increase in mortality was recorded in the age group 35-39 years, with an average percentage increase of 31.4  and in the age group of 70-74 years, 12.9 .&#x0D; Conclusions: The trend of increasing mortality from malignant melanoma in Serbia is similar to those in most developed countries. Education and improvement of the awareness of the general population and among health professionals remain vital to reducing melanoma mortality in the future.</jats:p

The gas holdup in a multiphase reciprocating plate column filled with carboxymethylcellulose solutions

Gas holdup was investigated in a gas-liquid and gas-liquid-solid reciprocating plate column (RPC) under various operation conditions. Aqueous carboxymethylcellulose (sodium salt, CMC) solutions were used as the liquid phase, the solid phase was spheres placed into interplate spaces, and the gas plase was air. The gas holdup in the RPC was influenced by: the vibration intensity, i.e., the power consumption, the superficial gas velocity, the solids content and the rheological properties of the liquid phase. The gas holdup increased with increasing vibration intensity and superficial gas velocity in both the two- and three-phase system. With increasing concentration of the CMC PP 50 solution (Newtonian fluid), the gas holdup decreased, because the coalescence of the bubbles was favored by the higher liquid viscosity. In the case of the CMC PP 200 solutions (non-Newtonian liquids), the gas holdup depends on the combined influence of the rheological properties of the liquid phase, the vibration intensity and the superficial gas velocity. The gas holdup in the three-phase systems was greater than that in the two-phase ones under the same operating conditions. Increasing the solids content has little influence on the gas holdup. The gas holdup was correlated with the power consumption (either the time-averaged or total power consuption) and the superficial gas velocity