Ibraheem O. Ali

Novel Synthesis of Nay Zeolite from Rice Husk Silica: Modification withZno and Zns for Antibacterial Application

Zeolite Y in the sodium form (NaY) was synthesized using amorphous silica ash derived from waste rice husks under hydrothermal conditions. Structural characterization of NaY before and after modification with ZnO and ZnS has been done using powder X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), N2 adsorption-desorption at -196 °C, scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The effects of the Na2O/SiO2 and Si/Al ratios, aging temperature and crystallization time on the optimized synthesis of NaY were thoroughly investigated. Thus the regulated Na+ impurity concentration in the starting hydrogel was found to act as a template-assisted synthesis of zeolite NaY by the potential incorporation of Al atoms into the zeolite framework. Results of surface analyses indicate that the interactions of ZnO and ZnS with NaY zeolite are distinguishable and thus the higher interaction is observed for the latter. While ZnII has experienced electrostatic bonding interaction with the framework oxygen atoms, creation of mesopores in NaY due to local destruction of the zeolite lattice around the growing ZnS particles was evidenced. Wonderfully, ZnS/NaY exhibited a high performance in prohibiting the growth of Escherichia coli (E. coli) and negligible from P. Aeruginosa, and these important features make it a potential candidate as an antimicrobial agent for controlling implant-related infections.

Controllable synthesis of NaP zeolite and its application in calcium adsorption

NaP zeolite particles were prepared through a template-free hydrothermal condition at 100ºC. Parameters like Na2O/SiO2 and SiO2/Al2O3 molar ratios, gel aging time and aging temperature were investigated for regulating the crystallization of the final product. The samples at different synthesis stages were characterized with N2 adsorption at −196ºC, field emission scanning electron microscopy (FE-SEM), temperature programmed desorption of ammonia adsorption, X-ray diffraction, thermogravimetric and differential scanning calorimetry analysis and Fourier transform infrared spectroscopy. The experimental results evidenced that a high ordering crystallinity of NaP zeolite was obtained at Na2O/SiO2 and SiO2/Al2O3 molar ratios of 1.10 and 1.40, respectively, and a temperature of 100°C for 4 days of aging. FE-SEM image exhibited polycrystalline aggregates of NaP zeolite with crystallite sizes ranging up to 5.04 μm with cactus/cabbage like structures. The quantitative analysis of the total number of acid sites was found to increase as Na2O increases. The NaP zeolite sample with a Na2O/SiO2 molar ratio of 1.13 exhibited a large fraction of the acid sites on its external surface, contrary to that synthesized with a relevant ratio of 1.10. The optimized NaP zeolite could be successfully bestowed with excellent sorption properties of Ca(II) in aqueous solution. The kinetic parameters for Ca(II) adsorption were thoroughly investigated.中文摘要本文通过无模板水热法在100°C条件下制备了NaP沸石分子筛, 并研究了Na2O/SiO2和SiO2/Al2O3摩尔比、凝胶老化时间和老化温度等参数, 以调节最终产品的结晶度. 不同合成阶段的样品,用−196°C氮吸附、场发射扫描电子显微镜(FE-SEM)、氨程序升温脱附、X-射线衍射、热重和差示扫描量热分析以及傅里叶变换红外光谱法进行了表征. 实验结果表明, 在Na2O/SiO2和SiO2/Al2O3摩尔比分别为1.10和1.40, 100°C温度下老化4天, 可以获得高度有序结晶化的NaP分子筛. FE-SEM图像显示NaP分子筛的多晶聚集体晶粒尺寸可达5.04 μm, 具有仙人掌/卷心菜样结构. 定量分析发现酸位点总数随Na2O的增加而增加, Na2O/SiO2摩尔比为1.13的NaP沸石样品与1.10摩尔比合成的样品相比, 在外表面上具有大量的酸位点. 优化后的NaP分子筛在水溶液中具有优异的钙离子吸附性能, 本文对 钙离子吸附动力学参数进行了详细研究.

Synthesis and characterization of copper(II) complexes of sulfadiazine with amino acids: catalytic activity toward oxidation of phenol and catechol

New copper complexes of DL-methioninoylsulfadiazine (MTS) and L-cystinoylsulfadiazine (CYS) were prepared and characterized using elemental analysis, IR, electronic spectroscopy, EPR spectroscopy, and thermal analysis. The mode of binding indicates that copper binds to MTS through carbonyl oxygen with the amino group nitrogen while for CuII–CYS the copper binds through carbonyl oxygen and SH with removal of its proton. The proposed structures were supported by conformational analysis which showed predominance of the trans form of copper(II)-L-cystinoylsulfadiazine. The two complexes enhanced oxidation of phenol and catechol in the presence of H2O2 under mild conditions. The catalyst shows proficiency toward oxidation of phenol and catechol compared to the auto-catalytic oxidation. CuII–MTS exhibited higher catalytic activity than CuII–CYS. The phenol and catechol oxidation is inhibited by Kojic acid.

Tuned interactions of silver nanoparticles with ZSM-5 zeolite by adhesion-promoting poly(acrylic acid) deposited by electrospray ionization (ESI)

Abstract The electrospray ionization (ESI) method was used for deposition of thin films of poly(acrylic acid) (PAA) on Cu/ZSM-5 (5 wt.% Cu) and Ag–Cu/ZSM-5 (1 wt.% Ag and 4 wt.% Cu) composites. For comparative purposes, the ZSM-5 zeolite was synthesized under hydrothermal conditions and loaded with PAA under the same treating conditions as the composites. This method allowed the formation of uniform polymer films of controlled thickness on conductive substrates. The structural characteristics were characterized by X-ray photoelectron spectroscopy, Fourier-transform infrared spectroscopy, atomic force microscopy and X-ray diffraction (XRD). The deposited PAA layer over ZSM-5 acts as a common dispersing and stabilizing agent through coordination-driven guest-templated polymer via interaction of Ag+ and Cu2+ with carboxylic acid groups, thus increasing and controlling the adhesion and the release of metallic species. A short exposure to light and temperature has reduced the metal ions to Cu0 and Ag0 metallic nanoparticles. The results of XRD analysis let suggest that the interaction of Cu and Ag with carboxylic groups of PAA inhibits the formation of large metallic silver particles. These samples were being studied for their potential as antibacterial agents toward the bacterial strains such as Staphylococcus pneumonia, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa as Gram positive and Gram negative bacteria, respectively. Aspergillus fumigatus and Candida albicans as Fungi were also evaluated. The Cu/ZSM-5 and Ag–Cu/ZSM-5 nanocomposites coated with a 10 nm thick PAA layer exhibit significant antibacterial activity.

HYDROTHERMAL SYNTHESIS AND CHARACTERIZATION OF NANO SIZED ZSM-5 AND THEIR EFFECT ON THE DECOLORIZATION OF INDIGO CARMINE DYE

Silica sources can influence different effects of ZSM-5 crystallization and it leads to change in the properties of the final product. The crystallinity of nanosized ZSM-5 zeolite from precursors mixtures containing different silica sources, e.g. tetraethylorthosilicate (TEOS), colloidal silica (CS), silicic acid(SA) and fumed silica(FS) have been studied. The produced samples are investigated using XRD, SEM, FT-IR, pyridine adsorption and N2 adsorption measurements. XRD results show that the product obtained by different silica sources is nano sized ZSM-5 phase. SEM results show that silica sources influences on shape of the produced ZSM-5; the sample which was prepared by silicic acid crystallized in spherical shape crystals, the samples which was prepared by TEOS crystallized in cubical shape crystals, the sample which was prepared by colloidal silica crystallized in spherical shape crystals with smaller aggregated but the sample which was prepared by fumed silica crystallized in round shape crystals. N2 adsorption results show that silica sources influences on pore diameter and pore volume of the produced ZSM-5.The adsorption of indigo carmine dye by ZSM-5 has been studied. It was found that the synthesized zeolite by SA exhibited significantly higher adsorption capacity for indigo carmine than other ZSM-5 states due to the difference in morphological properties. The optimum ZSM-5 loading is 1 g at pH 4 after 180 min.