Nitrate Removal Using Pumice Aggregate Coated with Zeolite Nanoparticles Modified by Cationic Surfactant from Synthetic Aqueous Solutions

High nitrate concentration in water resources leads to many health and environmental problems. In this study, stabilization of the zeolite nanoparticles modified by cationic surfactant was applied on the pumice bed to remove excess nitrate from aqueous solutions. Zeolite nanoparticles, following modification by CTAB surfactant, were stabilized on the substrate of pumice aggregate and their physical and structural characteristics were investigated by XRD, EDAX, and SEM analyses. In this research, the response surface method based on the Box-Behnken model was used to evaluate the effects of independent variables pH (5-9), temperature (15-45 ºC), and adsorbent dosage (5-15 g) on the response function and to predict the best response value. The results revealed that the maximum nitrate removal efficiency predicted by the model was 52.26 % in optimal conditions (temperature 34°C, pH 5 and adsorbent amount of 15 g). Also, the nitrate removal rate was increased by increasing the adsorbent dosage and contact time, while the removal efficiency decreased with increasing pH and initial nitrate concentration. The study showed that the modified pumice aggregates could be used as an effective and economical adsorbent for removal of pollutants.