ABSTRACT: A method for routine determination of fluorine, chlorine and bromine in household products was developed and validated. In this work, halogen analyses were made based on oxygen bomb combustion followed by ion chromatography (IC). The chromatographic analysis was performed by an IonPac AS19 hydroxide-selective anion-exchange column, a reagent free ion chromatograph eluent generator and an anion self-regenerating suppressor in 10 min. The response was linear (r ≥ 0.9995) in the entire investigated domain. The limit of detection for the halogens was in the range of 2 to 9 × 10(-3) mg/L and the limit of quantification was lower than 8 mg/Kg with 20 µL of injection volume. The certified reference material of ERM-EC 681k was pretreated using an oxygen bomb combustion procedure to demonstrate the precision of the proposed method. The quantitative analysis results obtained by IC for the target elements were 797 ± 9 mg/Kg chlorine and 786 ± 25 mg/Kg bromine, which were in good agreement with the certified values of 800 ± 4 mg/Kg chlorine, 770 ± 5 mg/Kg bromine for ERM-EC 681k, respectively. This validated method was successfully applied for the analysis of fluorine, chlorine and bromine in household product samples, and the variation of halogen contained among the tested samples was remarkable.
Journal of chromatographic science 06/2012; · 0.88 Impact Factor
ABSTRACT: AbstractA novel micro-micro/mesoporous silicoaluminophosphate ZSM-5-SAPO-5/MCM-41 (define as MZS-5) composite material with regular
spherical morphology was synthesized through a novel process of the self-assembly of CTAB surfactant micelles with silica-alumina
source which originated from the alkaline treatment of ZSM-5 zeolite. The physical properties of the MZS-5 composite material
were characterized by XRD, FT-IR, Nitrogen adsorption–desorption, SEM and Py-FTIR techniques. Catalytic tests showed that
the MZS-5 composite catalyst exhibited higher catalytic activity compared with the conventional microporous ZSM-5, SAPO-5
zeolite and mesoporous Al-MCM-41 molecular sieve for catalytic cracking of 1,3,5-triisopropylbenzene (TIPB). The remarkable
catalytic reactivity of TIPB molecules was mainly attributed to the presence of the hierarchical zeolite structure. In the
MZS-5 structure, the mesopores provided pathways for transportation of larger molecules and the microporous ZSM-5 and SAPO-5
zeolite provided acidic sites for catalytic activity.
Graphical AbstractA novel micro-micro/mesoporous silicoaluminophosphates MZS-5 catalyst exhibited higher catalytic activity than microporous
ZSM-5, SAPO-5 and mesoporous Al-MCM-41 for catalytic cracking of 1,3,5-triisopropylbenzene due to its hierarchical porosity.
Journal of Porous Materials 04/2012; 18(1):69-81. · 1.24 Impact Factor
ABSTRACT: Novel hierarchical zeolites with continuous micrometer-scale macropores and mesopores other than popular nanometer-scale mesopores
and micropores were synthesized by transforming the skeletons of the silica monolith into zeolites through both the steam-assisted
conversion and nanocasting methods. Results showed the novel hierarchical zeolites exhibited high catalytic activity for catalytic
cracking large molecules.
KeywordsHierarchical zeolites-Catalytic cracking
Catalysis Letters 04/2012; 136(3):266-270. · 2.24 Impact Factor
ABSTRACT: Zeolite beta monoliths with hierarchical porosity were prepared by the steam-assisted conversion of pre-seeded bimodal pore
silica gel using the Layer-by-Layer process. The bimodal pore silica gel acts as both macrotemplates and silica source. The
zeolite beta monoliths were characterized by X-ray diffraction, scanning electron microscopy, IR absorption spectra and nitrogen
adsorption measurements. This zeolite beta monolith had hierarchical porosity: the unique micropores within the zeolite, the
small macropores generated by aggregation of crystallites and three dimensionally interconnected macropores formed by template
of silica gel. It is believed that the hierarchical structured zeolite monoliths will show good properties and potential applications
the fields of catalyst, ion exchange, and adsorption.
Journal of Porous Materials 11/2008; 15(6):643-646. · 1.24 Impact Factor
ABSTRACT: Cu/SiO2 catalyst with bimodal pore structure was prepared by co-gelation reactions of tetramethoxysilane (TMOS) and copper nitrate
in the presence of poly (ethylene oxide) (PEO) with an average molecular weight of 10,000 and the catalyst of acetic acid.
In this process, the interconnected macroporous morphology was formed when transitional structures of spinodal decomposition
were frozen by the sol–gel transition of silica. The addition of copper into the silica–PEO system had a negligible effect
on the morphology formation. In gel formation, it was found that the crystallite sizes of the CuO estimated from the peak
width in the Cu/SiO2 with the presence of PEO were not small as expected. It was considered that there was no obvious interaction between the Cu
cation and PEO, most of the copper ions in wet silica gel were present in the outer solution. They easily aggregated as copper
salts in the drying process of wet gel and decomposed into CuO particles in heating. While in the Cu/SiO2 with the absence of PEO, the Cu was selectively entrapped as small particles in the gel skeleton due to the interaction between
Cu aqua complex and silica gel network.
Journal of Materials Science 01/2007; 42(19):8320-8325. · 2.02 Impact Factor
ABSTRACT: A hierarchical zeolite catalyst was synthesized by transforming the skeletons of a bimodal pore silica gel into a zeolite through a steam-assisted conversion method, and shows high catalytic activity and a long catalyst lifetime for catalytic cracking of large molecules.
Chemical Communications 05/2006; · 6.17 Impact Factor