Water pollution has become a great problem and aroused worldwide concern. As a new class of materials, metal-organic frameworks (MOFs) exhibit significant potential for wastewater treatment due to their high surface area, porosity, stability and tunability. In this work, flower-like hierarchical Ni-Zn MOF microspheres were synthesized via a facile solvothermal method. The mole ratio of Ni to Zn had a great influence on the morphology and microstructure of the final products. With the increase mole ratio of Zn to Ni, the morphology of MOFs gradually changed from spheroidal structure to rod-like structure. Using the Congo red (CR) experiment to evaluate the adsorption performance, Ni-Zn MOF displayed superior adsorption capacity towards CR (460.90 mg g −1 ), compared with Ni MOF (276.70 mg g −1 ) and Zn MOF (132.20 mg g −1 ). Besides the tuned morphology and pore structure, electron transferring from Zn species to Ni species would also favor the physicochemical adsorption of Ni-Zn MOF towards CR.
Shuang Zheng,Lin Ding,Feilong Hu,Yong Zhang,Zhaofeng Ouyang,Shujuan Yang
In this work, the novel metal organic frameworks/multi-branched nanocellulose (Ni-Zn MOF@Multi CNC) fillers with different three-dimensional nanostructures are fabricated via two in-situ growing strategies, which were blended into Polyether sulfone (PES) matrix to construct composite ultrafiltration (UF) membranes. Furthermore, the effects of two structures of fillers on construction and performance of composite membranes are detailed investigated here. The results confirmed that the obtained PES composite membranes exhibited excellent permeability and selectivity because of the ultra-high hydrophilicity, abundant pores, and more negative charge of Ni-Zn MOF@Multi CNC fillers. Besides, compared with nanosphere structure of Ni-Zn MOF@Multi CNC, the nanoflower filler could provide more pores and cavities to enable higher water permeance, and more active surface charge (more -COO- groups) to increase protein rejection. The Ni-Zn MOF@Multi CNC 0.05 /PES membrane showed an 83 % higher permeance (up to 1151.00 L/m 2 h) and greatly improved BSA rejection (99 %). The Ni-Zn MOF@Multi CNC 0.05 /PES membrane has been successfully applied to different wastewater treatment, and shows expectant ultrafiltration performance.
Ning Zhang,Chuanhui Huang,Ping Tong,Zunmei Feng,Xiaoping Wu,Lan Zhang
Volatile polycyclic aromatic hydrocarbons (PAHs) in water and soil are associated with status in the human body. Development of simple, efficient detection method is challenging due to the coating could be attacked by the abundance of water in the direct-immersion solid-phase microextraction. The stability of coating is essential to the analysis results. In this paper, a stable Ni-Zn MOF/g-C 3 N 4 (MG NFs) nanoflowers with cavity traps structure was firstly reported and acted as solid-phase microextraction (SPME) adsorbent for PAHs. Markedly enhanced moisture and acid stability of the MG NFs was obtained through the doping the hydrophobic graphitic carbon nitride (g-C 3 N 4 ) and metal ions into metal organic frameworks (MOFs). The aperture environment and ambient environment of MG NFs were changed by the doping of the Ni and the g-C 3 N 4, respectively. The moisture and acid stability of MG NFs were prominently increased under the dual protection. Compared to commonly used commercial coatings, the MG NFs own large surface area, unique nanoflowers structure and numerous open metal sites on the nanosheets, which demonstrated significant extraction superiority for PAHs. The MG NFs coated fiber was used for the SPME preconcentration of PAHs and couped with GC–MS for detecting PAHs. It presented low detection limits (0.1–3.0 ng L −1 ), wide linearity (0.3–5000.0 ng L −1 ) and good linearity (the correlation coefficient >0.9951). The inter-day and intra-day relative standard deviation (RSD) (n = 3) for three replicate extractions using one fiber was 3.8%–9.1%, and 3.5%–9.2%, respectively. The fiber-to-fiber reproducibility (n = 3) was 4.2–11.8%. The coupling method was successfully applied in the analysis of real water and soil samples with satisfactory recoveries of 82.9–109.2%, 84.2–106.4%, and the corresponding RSDs were 2.4–11.3%, 3.6–10.8%, respectively. The results indicated the effectiveness of NG NFs coated fiber in further practical application.
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