Performance of surfactant-modified *BEA-type zeolite nanosponges for the removal of nitrate in contaminated water: Effect of the external surface.

Hierarchical *BEA-type nanosponges zeolite with a high external surface area (116 m.g) and small crystal size, synthesized in the presence of a dual-porogenic organic compound, were modified with a cationic surfactant (HDTMABr: hexadecyltrimethyl ammonium bromide) in order to create a new anion exchanger system: the surfactant-modified zeolite nanosponges (SMZ). For comparison, two other surfactant-modified *BEA-type zeolite materials, SMZ and SMZ, were obtained by modifying the synthesized conventional micron-size microcrytals and nanocrystals *BEA-type zeolite with HDTMABr, respectively. Textural and structural properties were determined for the three prepared materials using N adsorption/desorption analysis, XRD, SEM, and TEM. Nitrate adsorption isotherms were drawn in a large concentration range [0.8-24.2 mmol.L] and fitted with Langmuir isotherm model. The maximum nitrate removal capacity (1338 mmol.Kg/83 mg.g) was obtained for SMZ material. This value is the highest ever observed for nitrate removal using surfactant-modified zeolite. The nitrate removal kinetics were fitted with the pseudo second-order model for both materials SMZ and SMZ.