Pyrolysis experiments with resids and isolated asphaltenes from Arabian Light and Arabian Heavy feedstocks were compared with previous experiments with Hondo and Maya feeds to determine the effect of reaction environment on reaction paths, kinetics, and mechanisms. The experiments were at temperatures of 400, 425, and 450 °C for holding times ranging from 20 to 180 min in microbatch reactors. Reaction products were recovered as gas, maltene, asphaltene, and coke lumps. The maltene, asphaltene, and coke product fractions were collected by a solvent extraction sequence where heptane-soluble material was defined as maltene, toluene-soluble material as asphaltene, and toluene-insoluble material as coke. Gas chromatography revealed the presence of C 1 -C 5 paraffins, C 2 -C 5 olefins, isoparaffins, H 2 S, and CO 2 . Results were summarized by a lumped reaction network that allowed for quantitative kinetics analysis. Comparison of relative kinetics and apparent activation energies yielded insight into thermal reaction pathways, feedstock effects, and asphaltene environment effects. At 400 and 425 °C, isolated asphaltene reacted selectively to maltene. At 450 °C, asphaltene reacted predominately to coke. Isolated maltene pyrolysis indicated that asphaltene and coke formed in series, i.e., maltene f asphaltene f coke.

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The aim of this study is to investigate the antibacterial properties and characterization of chitosan-silver nanoparticle composite materials. Chitosan-silver nanoparticle composite material was synthesized by adding AgNO3and NaOH solutions to chitosan solution at 95°C. Different concentrations (0,02 M, 0,04 M, and 0,06 M) of AgNO3were used for synthesis. Chitosan-silver nanoparticle composite materials were characterized by Transmission electron microscopy (TEM), X-ray diffraction (XRD), ultraviolet (UV) spectrophotometer, and Fourier transform infrared (FTIR) spectrometer techniques.Escherichia coli,Acinetobacter baumannii,Staphylococcus aureus,Enterococcus faecalis,Pseudomonas aeruginosa, andStreptococcus pneumoniaewere used to test the bactericidal efficiency of synthesized chitosan-Ag nanoparticle composite materials. The biological activity was determined by the minimum bacterial concentration (MBC) of the materials. Antibacterial effect of chitosan-silver nanoparticle materials was increased by increasing Ag amount of the composite materials. The presence of small amount of metal nanoparticles in the composite was enough to significantly enhance antibacterial activity as compared with pure chitosan.

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