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Hydroxy double salts (HDSs) have shown enormous potential for removing dyes from wastewater. However, the powder form of HDSs limits their potential in commercial applications. Herein, we proposed a facile one-step route to incorporate CuZn-HDS into the copper alginate matrix for methyl orange removal. This strategy could not only shape CuZn-HDS to beads but also significantly enhance the adsorption ability of the matrix. The obtained composite hydrogel beads displayed high water stability and excellent adsorption performance for MO, with more than 98% of MO being removed by CuZn-HDS/Alg-0.5. The maximum adsorption capacity of CuZn-HDS/Alg-0.5 for MO was 763.3 mg·g−1 at 298 K. Besides, the adsorption process matched the pseudo-second-order kinetic model and fitted well with the Freundlich model, suggesting that the adsorption of MO onto CuZn-HDS/Alg-0.5 was a multilayer chemical adsorption process. More importantly, CuZn-HDS/Alg-0.5 could selectively adsorb MO from MO & RhB (Rhodamine B) and MO & MB (Methylene blue) mixed solution. Mechanism studies indicated that the removal of MO was attributed to the electrostatic interaction, complexation interaction and ion exchange interaction between MO and CuZn-HDS/Alg-0.5. This work opens a new route for developing eco-friendly and efficient adsorbents to remove dyes from wastewater. [Display omitted] [ABSTRACT FROM AUTHOR]

The relatively high cost, long synthesis duration and low adsorption capacity have limited the application of the primary metal-organic frameworks (MOFs) in the heavy metal removal. Herein, one-minute synthesized primary HKUST-1 MOF with excellent adsorption performance towards Pb2+ has been achieved. The adsorption equilibrium time and maximum uptake capacity of Pb2+ on HKUST-1were 60 min and 819.28 mg/g, respectively. Besides, HKUST-1 exhibited a stronger binding affinity to Pb2+ than the coexisting ions. The adsorption data fitted well with the pseudo-second order model (R2 = 0.9962) and Langmuir model (R2 = 0.9919), suggesting the adsorption behavior was dominated by monolayer chemisorption. Further, the destruction of HKUST-1 crystal structure after Pb2+ exposure and strong correlation between the released Cu2+ and adsorbed Pb2+ collectively confirmed the ion exchange could be the potential mechanism. Besides, the coordination interaction between Pb2+ and the free-standing carboxylate groups in the ligands of HKUST-1 also played an important role in the adsorption process. This work not only provides a new idea for Pb2+ removal by primary MOFs based on cation substitution, but also has great implications for constructing green and low-cost MOFs for the treatment of heavy metals contaminated water. [Display omitted] [ABSTRACT FROM AUTHOR]

The relatively high cost, long synthesis duration and low adsorption capacity have limited the application of the primary metal-organic frameworks (MOFs) in the heavy metal removal. Herein, one-minute synthesized primary HKUST-1 MOF with excellent adsorption performance towards Pb2+ has been achieved. The adsorption equilibrium time and maximum uptake capacity of Pb2+ on HKUST-1were 60 min and 819.28 mg/g, respectively. Besides, HKUST-1 exhibited a stronger binding affinity to Pb2+ than the coexisting ions. The adsorption data fitted well with the pseudo-second order model (R2 = 0.9962) and Langmuir model (R2 = 0.9919), suggesting the adsorption behavior was dominated by monolayer chemisorption. Further, the destruction of HKUST-1 crystal structure after Pb2+ exposure and strong correlation between the released Cu2+ and adsorbed Pb2+ collectively confirmed the ion exchange could be the potential mechanism. Besides, the coordination interaction between Pb2+ and the free-standing carboxylate groups in the ligands of HKUST-1 also played an important role in the adsorption process. This work not only provides a new idea for Pb2+ removal by primary MOFs based on cation substitution, but also has great implications for constructing green and low-cost MOFs for the treatment of heavy metals contaminated water. [Display omitted] [ABSTRACT FROM AUTHOR]