Environment Protection Engineering Vol. 43 2017 No. 4 DOI: 10.5277/epe170407 AREF ALSHAMERI 1, 2 , HONGPING HE 1 , AMMAR SALMAN DAWOOD 3 , JIANXI ZHU 1 SIMULTANEOUS REMOVAL OF NH 4 + AND PO 4 3− FROM SIMULATED RECLAIMED WATERS BY MODIFIED NATURAL ZEOLITE. PREPARATION, CHARACTERIZATION AND THERMODYNAMICS Natural zeolite was modified by NaCl, AlCl3 and thermal treatment for the removal of NH4 + and PO4 3− ions. The characteristics of the modified zeolite (AlZ) and its mechanism for the NH4 + and PO4 3− removal were studied and compared. The results showed that the surface area and the Na + and Al 3+ content increased whereas the content of Ca 2+ , K + and Mg 2+ decreased after zeolite modification. On natural zeolite when activated with the 1 M NaCl and 10 cm 3 /g of pillaring dosage, high adsorption efficiencies for the NH4 + (97.80%) and PO4 3− (98.60%) were obtained. The results of various analyses indicated that the Na + exchange is the main mechanism for NH4 + removal whereas the adsorption mech- anism for PO4 3− followed the complexation with Al–OH groups present in the AlZ. In addition, the kinetics study showed that the adsorption of NH4 + and PO4 3− followed pseudo-second order model while the adsorption isotherm of NH4 + and PO4 3− is consistent with the Langmuir isotherm model. Moreover, the Gibbs free energy change for the simultaneous removal of the ions indicates that NH4 + is adsorbed faster compared to PO4 3− . The simultaneous removal of NH4 + and PO4 3− by AlZ adsorbent is cost effective in water treatment at low ion concentrations. 1. INTRODUCTION Eutrophication is a major problem of surface water resulting primarily from NH 4 + and PO 4 3− pollution [1]. NH 4 + and PO 4 3− ions are major components of most fertilizers and detergents. More often these chemicals find their way into water bodies either through _________________________ 1 CAS Key Laboratory of Mineralogy and Metallogeny, and Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, PR China, corresponding author H. He, e-mail address: hehp@gig.ac.cn 2 Geological Survey and Mineral Resources Board, Ministry of Oil and Minerals, Sana’a, Yemen. 3 College of Engineering, University of Basrah, Basrah, Iraq.