Two novel Zn (II)​-based metal–organic frameworks for rapidly selective adsorption and efficient photocatalytic degradation of hazardous aromatic dyes in aqueous phase

Two novel Zn-MOFs constructed from 5-hydroxy-2-nitroisophthalic acid (H₂DIPA) and 5-(4-carboxy-2-nitrophenoxy)-2-nitroisophthalic acid (H₃BPPA), namely: {[Zn₂(DIPA)₂(bimp)₅]·DMF·2H₂O}_n (Zn-MOF 1), {[Zn₂(HBPPA)₂(bibp)₂]·2H₂O}_n (Zn-MOF 2) (bimp = 1,4-di(1H-imidazol-1-yl)butane, bibp = 4,4′-bis(imidazolyl) biphenyl), have been synthesized under solvothermal conditions and characterized by single crystal X-ray diffraction, elemental analysis, IR spectra, powder X-ray diffraction (PXRD) and thermogravimetric analysis (TG). The single-crystal X-ray diffraction analysis indicates that Zn-MOF 1 exhibits an uncommon 3-nodal framework with a (4·6·8)(4·6³·8²)(6⁶) topology, whereas Zn-MOF 1 exhibits an uninodal 4-connected framework with a (4⁴·6²) topology. Moreover, both of the two Zn-MOFs exhibit exceptional dye adsorption capacities towards the organic dyes with high adsorption rates and excellent adsorption amounts. Particularly, Zn-MOF 1 can selectively adsorb the cationic dye malachite green (MG) whereas Zn-MOF 2 adsorb the anionic dye methyl orange (MO) when there exists another kind of dye in the system. The adsorption process can be illustrated by pseudo-second order kinetic and Langmuir isotherm, and the feasible adsorption mechanism could be the electrostatical interactions, hydrogen bonding between the MOFs and the dyes. Meanwhile, the two Zn-MOFs also show good photocatalytic degradation capabilities toward MB/MV dyes under UV irradiation, and the mechanism studies demonstrate that the main active species are ·OH radicals. Therefore, this functional MOF materials can be treated as a convenient and cost-efficient solution for the sewage handling and environmental protection.     

硫酸—氯酸钠—氯化钠法制二氧化氯中ClO2／Cl2的选择性研究

利用原料一次加入进行间歇反应、抽真空连续吸收产品气体的实验方法，进行了硫酸－氯酸钠－氯化钠法制二氧化氯中ＣｌＯ２／Ｃｌ２的选择性研究。实验结果表明：当采用较高的反应原料浓度、酸度和反应温度、ＮａＣｌ／ＮａＣｌＯ３的摩尔配比为１．１进行反应时，可获得产品气体中较高的ＣｌＯ２／Ｃｌ２的选择性     

高渗透支撑SBS膜制备与CH4/N2分离性能

苯乙烯–丁二烯–苯乙烯嵌段共聚物(SBS)具有软硬段互相结合的独特结构,可通过挤压实现对气体分子的分离。本文以多孔α-Al₂O₃陶瓷管为载体,利用一系列x-SBS/四氢呋喃(THF)树脂溶液制备了相应的SMS-x分离膜。FTIR、XRD、SEM等表征测试结果表明,SBS树脂与载体之间可较好结合,分离膜厚度均小于50 μm。气体测试表明,在0.05~0.3 MPa压力范围内,SMS-20分离膜对CH₄/N₂气体选择性(α)最优,在0.1 MPa时,α(CH₄/N₂) =3.81,CH₄的摩尔通量为1.41×10⁻⁶ mol·m⁻²·s⁻¹·Pa⁻¹。在0.3 MPa,SMS-10的CH₄摩尔通量最大,可达3.47×10⁻⁶ mol·m⁻²·s⁻¹·Pa⁻¹。此外,通过不同比例混合气体的测试验证了本文制备的分离膜同样可胜任相应的分离工作。本文制备的所有分离膜在0.1 MPa压差下可稳定分离气体长达7 d,具有良好的性能稳定性。因此,多孔α-Al₂O₃支撑型SBS分离膜可兼备优异的渗透通量及气体选择性,在煤层气CH₄的富集方面提供有利选择。