Levent Degirmenci

Esterification of Lauric Acid with Glycerol in the Presence of STA/MCM-41 Catalysts

Abstract Esterification reaction between glycerol and lauric acid in the presence of STA/MCM-41 and H2SO4 catalysts indicated that the activity of synthesized catalyst had been comparable to H2SO4. On the other hand, only di glyceride formation instead of favored mono glyceride has been observed with H2SO4 which had rendered the use of heterogeneous STA/MCM-41 catalyst preferable. Temperature had a decreasing effect on lauric acid conversion due to competitive adsorption of water on catalyst structure. The high mono glyceride selectivity obtained in favor of the desired product was due to shape selectivity of the catalyst. High glycerol amount in feed ratio resulted in deformation of long range order of the catalyst structure and hence a decrease in mono glyceride selectivity. Experiments conducted in identical conditions in the presence of recovered catalysts showed a decrease in lauric acid conversion which had been due to loss of STA from catalyst structure.

Effect of Atmosphere and Temperature Treatment on Leoanardite for Increasing Humic Acid Yield

Humic acid is a complex molecule including carboxylic, phenolic, alcoholic, and carbonyl fractions in its structure. Addition of this complex structure in soil improves its fertility by increasing its porosity along with water/nutrient capacity. Although naturally exists in soil, humic acid must be added to soil externally in regions with low soil fertility.The present study was conducted to provide insight on improving the efficiency of humic acid yield during its extraction. Leonardite was selected as raw material due to its higher amounts of humic acid compared to low rank coals, soil, agricultural crop residues, compost, sewage sludge, landfill leachate and animal waste. Leonardite was treated at 200, 300 and 400°C, in the presence of air and nitrogen atmospheres and humic acid was extracted from this treated samples. Compared to untreated leonardite, an improvement in humic acid efficiency was achieved for samples treated at 200°C, in the presence of nitrogen atmosphere. The reasons of this distinct behavior in the presence of nitrogen was elaborated with elemental, FT-IR, UV-Vis and XRD analyses.

Validation of Consecutive Coke and SiC Formation on Ni Core–Shell Microspheres During Methane Decomposition

Nickel based MCM-41(Ni/MCM-41) and silica microsphere (Ni/SiO2) were synthesized and tested against consecutive coke deposition and SiC formation in a model methane decomposition reaction. Results indicated coke deposition on both (Ni/MCM-41 and Ni/SiO2) catalysts and exclusive SiC formation due to utilization of coke deposited on Ni/SiO2 catalyst.Graphical Abstract

Effect of synthesis parameters on isoniazid (INH) release from silica nanospheres

Silica nanospheres containing isoniazid (INH) was synthesized based on a modified Stober process. Synthesis parameters such as type of alcohol used as oil phase, tetra ethyl ortho silicate (TEOS) and ammonia (NH 3 ) amounts, surfactant use and mixing time were altered and their effect on the release of INH was investigated. Results indicated lower amount of INH release when higher amount of TEOS was utilized in synthesis. Time of highest INH release was higher in the case of higher TEOS amount. NH 3 had also a decreasing effect on INH release which had been due to the changes in pore structure. Scanning electron microscope (SEM) results clearly showed the necessity of surfactant use with smooth surfaces obtained with the samples where surfactant was utilized. Finally, mixing time was found to have a decreasing effect on the time of highest INH release and the amount of INH released from the spheres was also higher in the case of higher mixing time.