Highly efficient removal of As(V) using metal–organic framework BUC-17

Arsenic contamination is a great threat worldwide due to its toxicity and hardly degradable. The development of highly efficient adsorbents is an essential challenge in the water treatment field. A 2D metal–organic framework [Co3(tib)2(H2O)12](SO4)3 (BUC-17) has been synthesized by hydrothermal method, and was utilized as an efficient adsorbent to remove As(V) from contaminated water. The results showed that BUC-17 have higher adsorption capacity toward As(V) than most counterpart adsorbents, its maximum uptake capacity reached 129.2 mg g−1 at 298 K. The adsorption kinetics and isotherm behaviors were well fitted with pseudo-second-order and Langmuir model, respectively. The thermodynamic parameters such as free energy change ΔG°, enthalpy change ΔH° and entropy change ΔS° were both negative during the sorption process, suggesting that the adsorption process of BUC-17 towards As(V) was spontaneous and exothermal. The influence of pH and foreign ions on the adsorptive removal of As(V) using BUC-17 were investigated. The results showed that pH values have significant influence while co-existed anions (unless phosphate) exert slight effect on adsorption capacity. Finally, a corresponding adsorption mechanism was proposed and confirmed by scanning electron microscopy, Fourier Transform infrared spectra (FTIR) and X-ray photoelectron spectroscopy analysis.