Document Type: Research Article
In this research the biochar ability of Conocarpus and Paulownia plant as adsorbents to remove Nitrate, Ammonium and phosphate from water was investigated. For this purpose the effect of contact time, initial concentration and pH of solution on removal of Nitrate, Ammonium and phosphate by the biochar of Conocarpus and Paulownia plants have studied. The Conocarpus and Paulownia plants have modified by ferrous chloride for nitrate removal. Conocarpus and Paulownia have modified by potassium hydroxide for ammonia removal. Also, Conocarpus have modified by ferrous chloride and Paulownia have modified by Potassium hydroxide for phosphate removal. The studied adsorbent properties with FTIR and SEM, which their physical properties are: density, organic material percent, ash percent, mass moisture and special surface have determined by methylene blue method. The Pseudo-First-order order, Pseudo-Second-order, Elovich, Intraparticle diffusion and power have used for describing the kinetic data. In addition, the Langmuir model, Freundlich, Temkin, Halsy and Langmuir-Freundlich have used for describing the isotherm adsorption data. The results of this study showed that the Nitrate, Ammonium and phosphate adsorption level have increased by passing the time and after 60 and 120 minute, they have reached their maximum level respectively. The maximum Ammonium adsorption level in modified biochar of Conocarpus was in pH=6, and in Palonia biochar was in pH=2 and the maximum nitrate adsorption was in pH=2. In addition, the maximum phosphate adsorption was in pH=8. By increasing the initial concentration of phosphate and nitrate, the removal efficiency has increased. The maximum phosphate removal efficiency in the concentration of 14mg/L in modified paulownia and Conocarpus biochar was 100%. In addition, the concentration of 50mg/L nitrate in modified Paulownia biochar was 98.37%. the maximum Ammonium removal efficiency in concentration of 5 mg/ L by modified Conocarpus biochar was 82%.