A novel highly efficient adsorbent {[Co 4 (L) 2 (μ 3 -OH) 2 (H 2 O) 3 (4,4′-bipy) 2 ]·(H 2 O) 2 } n : Synthesis, crystal structure, magnetic and arsenic (V) absorption capacity

Abstract A novel highly efficient adsorbent-microporous tetranuclear Co(II)-based polymer, {[Co 4 (L) 2 ( μ 3 -OH) 2 (H 2 O) 3 (4,4′-bipy) 2 ]·(H 2 O) 2 } n ( 1 , H 3 L = 4-(N,N′-bis(4-carboxybenzyl)amino) benzenesulfonic acid, 4,4′-bipy = 4,4′-bipyridine), was hydrothermally synthesized. The complex 1 is a metal–organic framework (MOF) material which was characterized by single-crystal X-ray diffraction, BET and platon software. Co-MOF (complex 1 ) reveals excellent adsorption property. The capacity of Co-MOF to remove arsenic As(V) from sodium arsenate aqueous solutions was investigated (The form of As(V) is AsO 4 3- ). The experimental results showed that Co-MOF had a higher stable and relatively high As(V) removal rate (> 98%) at pH 4–10. The adsorption kinetics followed a pseudo-second-order kinetic model, and the adsorption isotherm followed the Langmuir equation. Co-MOF exhibits a very high adsorption capacity of As(V) in aqueous solution (Q max of 96.08 mg/g). Finally, the optimal adsorption conditions for the model were obtained through a Box–Behnken response surface experiment which was designed with adsorption time, dose, temperature and rotational speed of the shaker as the influencing factors to determine two-factor interaction effects. Co-MOF was further characterized using FTIR, PXRD, X-ray photoelectron spectroscopy before and after adsorption As (V). The magnetism of Co-MOF was also discussed.