Effective As(V) removal using in situ grown Ti-based MOFs on ZnAl-LDHs

Herein, we synthesize the ZnAl-LDHs/NH2-MIL-125 composite via in situ growth of Ti-based metal–organic framework (MOFs) using layered double hydroxide (LDHs) as a carrier. The composite exhibits excellent performance for As(V) removal, achieving an adsorption capacity of 1634.0 mg/g in wastewater with an As(V) concentration of 1500 mg/L at pH of 10. The porous flower-like structure of the composite inherits the benefits of both the spatial structure of MOFs and the arsenic-affinity of LDHs. This results in an abundant active surface containing –OH, –NH2, M–O–M, and –COO– species, collectively contributing to As(V) adsorption. The adsorption progress governing As(V) removal follows the Langmuir isotherm and pseudo-second-order (PSO) kinetic models, revealing a monolayer and chemisorption mechanism. This study showcases the feasibility of the in situ growth of a MOF on LDHs to synthesize high-capacity adsorbents, offering a potential solution for As(V) removal from wastewater.