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The HKUST-1@SBA-15 composites with hierarchical pore structure were constructed by in situ self-assembly of metal-organic framework (MOF) with mesoporous silica. The structure directing role of SBA-15 had an obvious impact on the growth of MOF crystals, which in turn affected the morphologies and structural properties of the composites. The pristine HKUST-1 and the composites with different content of SBA-15 were characterized by XRD, N adsorption-desorption, SEM, TEM, FT-IR, TG, XPS, and CO-TPD techniques. It was found that the composites were assembled by oriented growth of MOF nanocrystals on the surfaces of SBA-15 matrix. The interactions between surface silanol groups and metal centers induced structural changes and resulted in the increases in surface areas as well as micropore volumes of hybrid materials. Besides, the additional constraints from SBA-15 also restrained the expansion of HKUST-1, contributing to their smaller crystal sizes in the composites. The adsorption isotherms of CO on the materials were measured and applied to calculate the isosteric heats of adsorption. The HS-1 composite exhibited an increase of 15.9% in CO uptake capacity compared with that of HKUST-1. Moreover, its higher isosteric heats of CO adsorption indicated the stronger interactions between the surfaces and CO molecules. The adsorption rate of the composite was also improved due to the introduction of mesopores. Ten cycles of CO adsorption-desorption experiments implied that the HS-1 had excellent reversibility of CO adsorption. This study was intended to provide the possibility of assembling new composites with tailored properties based on MOF and mesoporous silica to satisfy the requirements of various applications.

The feasibility of the electrogeneration of H2O2 and degradation of an organic pollutant by a novel electro-Fenton (EF) process was demonstrated using dual rotating graphite felt disks to supply oxygen instead of the traditional aeration method, with methyl orange (MO) as the model pollutant. The effects of rotating speed, current density, and pH on the generation of hydrogen peroxide (H2O2) were investigated. At a current density of 50 A/m2, a rotating speed of 10 rpm, and a pH of 3, the concentration of H2O2 reached 116 mg/L in 1 h, which was much higher than that at 0 rpm (37 mg/L). The complete removal of 25 mg/L MO was achieved within 15 min, while the total organic carbon removal efficiency reached 58.7% at 2 h, which was almost 3-fold higher than that at 0 rpm (14.9%). The rotation of disk cathodes resulted in the efficient production of H2O2 without oxygen aeration, offering a potentially cost-effective EF method for degrading organic pollutants.

Chemically modified graphite felt as an efficient cathode in electro-fenton for p-nitrophenol degradation. (2014) Electrochimica Acta, 140. 376-383.

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Conjugated microporous polymers (CMPs), linked by a covalent bond to form an extension of the aromatic ring skeleton, are microporous materials characterized by a highly conjugated structure and high stability. The present study reported on a novel strategy for the synthesis of CMPs with built-in magnetic nanoparticles for excellent enrichment of trace hydroxylated polycyclic aromatic hydrocarbons (OH-PAHs) in human urine. We modified Fe3O4 nanoparticles with boronic acid groups and then reacted the nanoparticles with reactive monomers of polyphenylene conjugated microporous polymer (PP-CMP) to anchor the magnetic components in the PP-CMP framework. Chemical bonding between Fe3O4 nanoparticles and PP-CMP networks, together with equally firm covalent linkage and rigidity of the PP-CMP network, endows the magnetic PP-CMP with remarkable chemical stability and durability, even in harsh conditions. Magnetic PP-CMP has the characteristics of high conjugation ability, highly porous structure, and magnetism, which makes it an ideal magnetic adsorbent for trace analytes with aromatic conjugation structure. The adsorption mechanism of OH-PAHs on magnetic PP-CMP was investigated and demonstrated that hydrophobic interaction was important for the contribution of interaction between adsorbents and target analytes, together with the assistance of π-π stacking interaction. For the application, the magnetic PP-CMP was used for the enrichment of trace OH-PAHs in human urine of both smokers and nonsmokers in combination with high-performance liquid chromatography with fluorescence detection (HPLC-FLD). It showed good selectivity and excellent sensitivity to these OH-PAHs. Their detection limits were low and in the range of 0.01-0.08 μg·L(-1). The OH-PAHs were detected with different amounts from 0.054 to 0.802 μg·L(-1) in urine samples from smokers and nonsmokers. The recoveries were found to be 76.0%-107.8%. The results indicate that the magnetic PP-CMP offers an efficient enrichment method for trace OH-PAHs in human urine.

Four new microporous isostructural anionic lanthanide metal-organic frameworks (Ln-MOFs), [(CH)NH][Ln(TATAT)(HO)]· x(solvent) {Ln = Tb, Eu, Dy, and Gd; HTATAT = 5,5',5″-(1,3,5-triazine-2,4,6-triyl)tris(azanediyl)triisophthalate}, were successfully constructed. The Ln-MOFs are three-dimensional (3D) anionic frameworks and have two sizes of square channels (8.9 × 8.9 Å and 4.3 × 4.3 Å) with a Lewis basic nitrogen-decorated pore environment. The 3D frameworks of Ln-MOFs can be simplified as (4,6)-connected she networks. Because of the anionic framework properties, Ln-MOFs can efficiently select and separate cationic dyes in the presence of anionic or neutral dyes of similar sizes. The adsorption amounts of methylene blue for Tb-MOF, Eu-MOF, Dy-MOF, and Gd-MOF are 147, 141, 133, and 143 mg g, respectively. Moreover, Tb-MOF and Eu-MOF allow easy detection and identification of ethanol, acetonitrile, and diethyl ether through solvatochromism. Diethyl ether vapor also rapidly changes the colors of Tb-MOF and Eu-MOF. The photoluminescence experiments show that the absolute quantum yields of Tb-MOF (upon excitation at 341 nm), Eu-MOF (upon excitation at 396 nm), Dy-MOF (upon excitation at 341 nm), and Gd-MOF (upon excitation at 370 nm) are 32.5%, 11.0%, 2.1%, and 7.1%, respectively. In addition, Tb-MOF can detect Co ion with high selectivity and quenching efficiency of 87%.