NH3 Removal from Sour Water by Clinoptilolite Zeolite: A Case Study of Tabriz Refinery

Sour water (SW) is one of the refinery effluents that is very dangerous for the environment and humans. In refineries, the use of conventional methods to remove contaminants, including ammonia (NH3), from SW is not very effective. This study proposes a method to remove NH3 from the refinery's SW and reduce its associated risks. In this study, for the first time, using the adsorption method and clinoptilolite adsorbent, the concentration of NH3 in SW decreased and reached the standard limit, which could be as an innovation for this research. The effect of pH, adsorbent dose, initial pollutant concentration, contact time, and temperature were investigated. Thermodynamics, kinetics, and isotherms were studied. The results were used to remove NH3 from the SW of Tabriz refinery. The optimal values ​​of the aforementioned parameters were 11, 1 g/100 mL, 50 mg/L, 30 min, and 25 °C, respectively. The results of the thermodynamic analysis showed that the adsorption process was exothermic, reversible and spontaneous in the test conditions. Experimental data were fitted better to the pseudo-second-order kinetics model and Langmuir isotherm model. After passing the SW through two consecutive fixed substrates, the NH3 concentration decreased from 400 mg/L to 2.3 mg/L, and the R% was 93.4%. According to the results of this study the proposed method can be used as a suitable method and suitable adsorbent to remove NH3 from the SW of refineries and effluents, due to its simplicity and high efficiency and the clinoptilolite due to its cheapness, abundance and ability to resuscitation.