Modification of NaY zeolite by lanthanum and hexadecyl trimethyl ammonium bromide and its removal performance for nitrate.

Abstract

Nitrate in the effluent of wastewater treatment plants (WWTPs) is the main nitrogen resource in natural water. The excessive nitrogen in natural water causes ecological issues such as aqueous eutrophication. A novel modified NaY zeolite (SMZ-La) with hexadecyl trimethyl ammonium bromide (HDTMA) and lanthanum (La) as modifying agents for -N adsorption was investigated in this study. Results showed that SMZ-La had a higher adsorption capacity (3.82mg -N/g) than zeolite only modified with HDTMA or La (2.75 and 2.23mg -N/g, respectively). Moreover, the adsorption process was endothermic with a maximum theoretic adsorption of 14.49mg -N/g. X-ray photoelectron spectroscopy (XPS) analysis indicated that adsorption rate principally depended on chemisorption between SMZ and -N. Thermogravimetric analysis showed that HDTMA was loaded on the surface of NaY zeolite with double layer. Scanning electron microscope and X-ray spectroscopy analysis illustrated that La was primarily loaded in the pore of NaY zeolite, and the loading of HDTMA and La did not affect the original crystal structure of NaY zeolite. The novel adsorbent provided a promising perspective for nitrogen control in WWTPs and natural water. PRACTITIONER POINTS: A novel modified zeolite (SMZ-La) was prepared successfully with HDTMA and La. SMZ-La had an excellent adsorption capacity compared to SMZ and NaY-La. There were both physical and chemical adsorptions in the adsorption process of SMZ-La on -N.