Nejdet Sen

Improvement of catalytic activity of lipase from Candida rugosa via sol–gel encapsulation in the presence of calix(aza)crown

Lipase from Candida rugosa (CRL) was encapsulated within a chemically inert sol-gel support in the presence of calix(aza)crowns as the new additives. The catalytic activity of the encapsulated lipases was evaluated both in the hydrolysis of p-nitrophenyl palmitate (p-NPP) and the enantioselective hydrolysis of racemic Naproxen methyl ester. It has been observed that the percent activity yields of the calix(aza)crown based encapsulated lipases were higher than that of the free lipase. Improved enantioselectivity was observed with the calix(aza)crown-based encapsulated lipases as compared to encapsulated free lipase. The reaction of Naproxen methyl ester resulted in 48.4% conversion for 24h and 98% enantiomeric excess for the S-acid, corresponding to an E value of >300 (E=166 for the encapsulated free enzyme). Moreover, the encapsulated lipases were still retained about 18% of their conversion ratios after the sixth reuse in the enantioselective reaction.

Removal of Trichloroethylene (TCE) in up Flow Anaerobic Sludge Blanket Reactors (UASB)

ABSTRACT Low concentrations of chlorinated aliphatic compounds may be found in wastewater and contaminated soils from different industrial sources and in the air arising from these sources. Low levels of Volatile Organic Compounds (VOC)s can be removed by adsorption, incineration and biofiltration methods. These methods have some disadvantages, such as low removal efficiency or high operation costs. Chlorine has been removed from the chlorinated aliphatic compounds by anaerobic conditions. The aim of this research was the investigation of biological treatment of VOCs in high flow speed reactors. The resistance capacity of micro-organisms was investigated in an upflow anaerobic sludge blanket reactor (UASB) with automated control system, by feeding with co-substrate additions, by loading different ratios of organic matter, varying hydraulic retention time (HRT), maintaining stable concentrations of COD and Volatile Fatty Acids (VFA), pH, alkalinity, temperature (35°C) etc. during the anaerobic treatment. Glucose, sodium sulphate, calcium chloride, ammonium bicarbonate, potassium phosphate and methanol were used as the co-substrates. In these studies the removal rates of TCE were approximately 86.4–90.0%. The decomposition ratios were calculated for TCE as 0,231 mg g−1 VSS d−1. The highest methane ratio in the obtained biogas was 67.8% for TCE. Also, inhibition concentrations (IC) in 24 hours were determined as IC50; 31.1 and IC25; 9.9.

Methane Production from Anaerobic Treatment of Volatile Organic Compounds (Voc)

Worldwide increasing energy problems guided to workers to find new and renewable energy sources. There are many new studies on energy investigation using different materials and technology. These studies were quite important for continuing development, comfortable life and industrial improvement. This investigation is considerable for removal of volatile organic compounds (VOC) frequently found in many wastewaters and methane production behind the wastewater treatment. The study performed in the up flow anaerobic condition sludge blanket (UASB) rectors. Used VOCs are trichloroethylene, chloroform, dichloromethane and tetrachlorethylene. Removal ratio of these compounds were 87.8% trichloroethylene (TCE), 96.5% chloroform (CF), 67.1% dichloromethane (DCM) and 97.3% tetrachlorethylene (PCE). Methane ratios in the gas production were 67.1% for trichloroethylene (TCE), 72.4% for chloroform (CF), 69.6% dichloromethane (DCM) and 69.8% tetrachlorethylene (PCE).

Gasoline- and diesel-like products from heavy oils via catalytic pyrolysis

ABSTRACT Heavy oil is less expensive than light crude oil, but heavy oil is more expensive to obtain light oil products. Conventional light crude oil resources are decreasing, therefore heavy oil resources will be needed more in the future. There are huge differences from field to field for heavy oil deposits. In terms of final productive use, heavy oil is considered as an unconventional resource. Heavy oil upgrading depends on four important factors: catalyst selection, heavy oil classification, process design, and production economics. Heavy and extra-heavy oils are unconventional reservoirs of oil. Globally, 21.3% of total oil reserves are heavy oil. Heavy oil is composed of long chain organic molecules called heavy hydrocarbons. The thermal degradation of the heavy hydrocarbons in heavy oil generates liquid and gaseous products. All kinds of heavy oils contain asphaltenes, and therefore are considered to be very dense material. The most similar technologies for upgrading of heavy oils are pyrolysis and catalytic pyrolysis, thermal and catalytic cracking, and hydrocracking. The amount of liquid products obtained from pyrolysis of heavy oil was dependent on the temperature and the catalyst. Pyrolytic oil contains highly valuable light hydrocarbons as gasoline and diesel components range. The constant increase in the use of crude oils has raised prices of the most common commercial conventional products and consequently seeking for new alternative petroleum resources, like some unconventional oil resources, becomes an interesting issue. The mass contents of gasoline, diesel, and heavy oil in the crude oil are 44.6%, 38.3%, and 17.1%, respectively. The gasoline yield from the heavy oil catalytic (Na2CO3) pyrolysis is higher than the diesel efficiency for all conditions. The yield of gasoline products increases with increasing pyrolysis temperature (from 230°C to 350°C) and percentage of catalyst (from 5% to 10%). The yields of gasoline-like product are from 21.5% to 39.1% in 5% catalytic run and from 32.5% to 42.5% in 10% catalytic run. The yields of diesel-like product are from 9.3% to 29.8% in 5% catalytic run and from 15.5% to 33.7% in 10% catalytic run.

Enhancing Effect of Calix[4]arene Amide Derivatives on Lipase Performance in Enantioselective Hydrolysis of Racemic Arylpropionic Acid Methyl Esters

Calix[4]arene amide derivatives were employed as new additives within the sol-gel encapsulation of lipase from Candida rugosa (CRL) to improve its catalytic properties. Evaluation of catalytic activity of the encapsulated lipases was acheived by enantioselective hydrolysis of both racemates, Naproxen methyl ester and 2-phenoxypropionic acid methyl ester, in aqueous buffer solution/isooctane reaction system. Results show that enantioselectivity was improved by using calix[4]arene amide derivatives-based encapsulated lipases. The reaction of naproxen methyl ester resulted in 47.6% conversion (x) in 24 h with 88.9% enantiomeric excess of substrate (ees), analogous to an enantioselectivity (E) value of 297 (E = 137 for the encapsulated free enzyme). The conversion of 2-phenoxypropionic acid methyl ester, obtained was 48.4% with E value of 327, enantiomeric excess of substrate (ees) of 92% for the reaction time of 1 h (E = 211 for the encapsulated free enzyme).

Calculation of higher heating values of hydrocarbon compounds and fatty acids

ABSTRACT Hydrocarbon compounds are formed by carbon and hydrogen elements. The higher heating values (HHVs) of the hydrocarbon compounds can be calculated based on the carbon (C) and hydrogen (H) contents of the chemical structures. HHVs (MJ / kg) as a function of the carbon (C) and hydrogen (H) fractions of N-saturated hydrocarbons can be calculated by the following equation: According to this Equation, the HHV is a function of the percentages of the carbon (C) and hydrogen (H) of pure n-saturated hydrocarbon compounds. This Equation represents the correlation obtained by means of regression analysis. It is found that the calculated values shows mean difference of 0.18%. The correlation coefficient is 0.9955. HHVs as a function of the iodine value (IV) and the saponification value (SV) of fatty acids can be calculated by the following equation: