In Situ Growth Synthesis of the CNTs@AC Hybrid Material for Efficient Nitrate-Nitrogen Adsorption

Nitrate-nitrogen (NO₃-N) is a common pollutant in aquatic environments and causes many environmental issues and health problems. This study successfully applied the activated AC@CNT composite synthesized by CNTs in-situ growth and post-treated by myristyltrimethylammonium bromide (MTAB) for NO₃-N adsorption from wastewater. The results show that the highest NO₃-N adsorption capacity of AC@CNTs-M was 14.59 mg·g^-1. The in-situ growth of CNTs gave a higher specific surface area and more mesoporous volume, while MTAB uniformly occupied part of the pore structure after the modification process. The AC@CNTs-M had more surface functional groups of hydroxyl and carboxyl, which are favorable for the adsorption of NO₃-N. The NO₃-N adsorption on AC@CNTs-M was best defined by the pseudo-second-order model, and the isothermal analysis shows that NO₃-N adsorption is a multiple process with a maximum adsorption capacity of 27.07 mg·g^-1. All the results demonstrate the great potential of AC@CNTs-M for NO₃-N adsorption from water, especially in acidic wastewater.