Removing nitrate from contaminated water using activated carbon prepared from hard pistachio shells

Background: Currently, due to the scarcity of water resources and the water shortage crisis, the preservation of contamination of water resources is of particular importance. Nitrate is one of the most hazardous pollutants in aquatic environments, which leads to many health and environmental problems. Thus, finding environmentally friendly solutions to remove nitrate from water sources is essential. This study examined hard pistachio shells as a raw material for the preparation of activated carbon and their use as an adsorbent. Materials and Methods: The experimental laboratory study explored factors affecting the absorption process including initial nitrate concentration, pH, absorption dosage, and reaction time on nitrate removal efficiency. The structural properties of the adsorbent were investigated by field emission scanning electron microscopy and the point of zero charge (pHpzc). Finally, the adsorption kinetics and isotherms were investigated. Results: Under optimize conditions, including initial nitrate concentration of 50 mg/L, adsorbent dosage of 0.2 g/L, pH equal to 5, and reaction time of 30 min, activated carbon can remove 99.4% of nitrate. The maximum adsorbent capacity was 211.6 mg/g. Nitrate removal follows quadratic kinetics and the Langmuir isotherm. Conclusion: The surface adsorption process using activated carbon prepared from hard pistachio shells can lead to the effective management of pistachio shells and has a significant efficiency in the removal of nitrates with high concentrations.