Preparation and application of a surfactant‐modified Halloysite nanotubes for the adsorption of nitrates from aqueous solutions: Kinetic and equilibrium studies

Abstract

AbstractThe current research proposes the hexadecyltrimethylammonium bromide‐modified Algerian halloysite nanotubes (HNTs‐CTAB) as adsorbent for nitrate ions removal from aqueous solution via electrostatic interactions. X‐ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), Fourier‐transform infrared spectroscopy (FT‐IR), and nitrogen adsorption–desorption analysis techniques have been used to characterize the prepared adsorbants. The different operating condition that may affect the adsorption of nitrate was carried out. HNTs and HNTs‐CTAB adsorption capacities are considerably pH dependent. The optimum conditions for maximum removal of nitrate from aqueous solution were as follows: adsorbent masse was 40 mg, initial pH was 4, temperature was 25°C, initial nitrate concentration of 100 mg/L and equilibrium time was 3 h. Under optimal value of process parameters, maximum NO3− adsorption capacity of 47.4 mg/g was obtained. Kinetic investigation confirmed that the nitrate adsorption on modified HNTs followed a pseudo‐second‐order with correlation coefficients greater than 0.98 (R2 = 0.9870) and that empirical Freundlich isotherm was best fitted nitrate equilibrium adsorption. The thermodynamic studies indicated that the adsorption of nitrate onto HNTs‐CTAB is endothermic and spontaneous. HNTs‐CTAB displayed high regeneration ability by retaining a capacity above 40 mg/g after four reuse cycles. HNTs‐CTAB containing plentiful nitrate could be returned to the soil directly as an economic slow release fertilizers or a soil amendment due to its environmental‐friendly performance. Therefore, HNTs‐CTAB used for remediation of wastewater might be employed easily as farmland fertilizer.