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• Two novel Co-mofs show unparalleled topologies frameworks. • Co-MOF 2 has proposed ultra-high adsorption capacity on CR (capacity: 810.7 mg g-1). • Co-MOF 2 has excellent adsorption potential in CR from the real wastewater. Removal the hazards of Azo organic dyes from waterbody through porous heterogeneous materials is considered as a low-cost and high-efficient method. Intriguingly, two metal organic frameworks (MOFs), {[C o 3 (L) 3 (H 2 O)]·3.5(C 4 H 2 O 2)} n and [Co 4 (L) 4 (bit) 2 ] n designated as MOF 1 and 2 , have been synthesized through the traditional solvothermal method. MOF 2 exhibits significant removal effect on organic dye (congo red (CR)) from waterbody owing to more imidazole rings in the structure than 1. After optimizing the experimental conditions, the highest adsorption capacity (810.7 mg g-1) and high removal rate (97.28%) of 2 are obtained in 500 ppm CR solution. Pseudo second-order kinetics and Langmuir isotherms more accurately described the adsorption process of 2. In addition, 2 exhibits high recyclability, stability and adsorption performance through a simple organic solvent release system. Moreover, 2 also exhibits high adsorption performance in real wastewater. The possible mechanism of selective adsorption involves the π-π stacking interaction, hydrogen bond, synergistic effect of electrostatic interaction and pore filling. All the bench experiments have indicated that 2 is a promising potential sorbent in the practical wastewater treatment and CR dyes recovery. Preliminary screening displays that 2 has proposed ultra-high adsorption capacity on CR, and its maximum adsorption capacity could reach 810.7 mg g-1. In addition, the adsorption process in accordance with the Langmuir isothermal model and the second-order kinetic model. Even in dye mixtures, CR could be selectively adsorbed, and the removal rate maintained 88% after six cycles. Finally, through dye classification, infrared analysis, SEM and BET tests, it was supposed that the adsorption of CR by 2 with the synergistic of electrostatic, π-π stacking and hydrogen bond interaction. In actual river water, the maximum adsorption capacity is as high as in bench results in deionization system. Therefore, our work provided 2 has excellent adsorption performance and potential application in CR extraction from the real wastewater. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract Two metal-organic frameworks (MOFs) {[Zn(L 1)]·2DMA·H 2 O} n (1) and {[Zn(L 2)]·2DMA·H 2 O} n (2) (H 4 L 1 /H 4 L 2 = 5,5'-(1,4/3-xylylenediamino) diisophthalic acid) were synthesized under solvothermal conditions and structurally characterized. Both of the crystals are isomorphs and featuring the dia topological 3D interpenetrated framework, and constructed with Zn(II) cations and two isometric aromatic tetracarboxylate ligands, respectively. The optical adsorption and diffuse-reflection spectrum show that the two crystals could be the potential UV photocatalytic materials, and photocatalytic studies exhibit great degradation activity of three organic dyes (methylene blue (MB), Rhodamine B (RhB) and Methyl orange (MO)). Graphical abstract Two dia isomorphic Zn-MOFs are synthesized based on two isomeric semi-rigid aromatic tetracarboxylate acids. The study of optical property and photocatalysis property of 1 and 2 indicates both are good candidates for the photocatalytic degradation of Rhodamine B, Methylene Blue and Methyl Orange. Image 1 [ABSTRACT FROM AUTHOR]

In this work, five novel Cd/Zn-based MOFs with different topological framework, namely {[Cd(bimb)(Hbipa)]·H 2 O} n (1), {[Cd 3 (dimb) 3 (bipa) 2 (H 2 O) 2 ·2H 2 O} n (2) , [Cd(bimd)(Hbipa)(H 2 O)] n (3) , {[Zn(bipd)(Hbipa)]·H 2 O} n (4) and [Zn(bimb)(Hbipa)] n (5) had been synthesized and characterized. Worth noting, Complex 1 and 2 had effective separation behaviors towards MO and MBE dyes respectively, which could reach the adsorption equilibrium within a quite short time even if there existed another kind of dye in the system. Meanwhile, Complex 3 – 5 showed great performance in CR adsorption. Additionally, Complex 3 – 5 also showed excellent photocatalytic degradation capabilities toward MB and MV dyes under UV irradiation. According to the study, these five metal-organic frameworks can be used as a kind of functional materials in the adsorption and photocatalytic degradation of organic dyes in wastewater. [Display omitted] • Produce novel Cd/Zn -based MOFs that possess novel 3D structure. • Selectively absorb specific aromatic dyes in a mixed aqueous system. • Exhibit efficient photocatalytic degradation abilities towards MB/MV in aqueous solution. [ABSTRACT FROM AUTHOR]