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

Herein, we synthesize the ZnAl-LDHs/NH 2 -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, –NH 2 , 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.