Abstract:
Objective To prepare modified carbon nitride with enhanced performance in adsorbing ammonia nitrogen in fish ponds.
Method Carbon nitride (s-C3N4) with basic adsorption capacity was prepared by co-heating of melamine and sodium bicarbonate using the thermal condensation method, and then s-C3N4 was further modified by disodium ethylene diamine tetraacetic acid (EDTA-2Na) to obtain modified carbon nitride (EDTA-s-C3N4). Scanning electron microscope (SEM), X-ray diffraction (XRD), BET surface area, and Zeta potential were used to characterize the materials.
Result The specific surface area of EDTA-s-C3N4 was as high as 17.7012 m2/g, and the surface potential was −19 mV. It had excellent adsorption performance for ammonia nitrogen in fish ponds with the removal rate of 72% at pH=7.5. The adsorption process conformed to quasi-second-order kinetics, and the maximum adsorption capacity estimated by Langmuir isothermal model fitting was 24.2131 mg/g. After five cycles of regeneration, EDTA-s-C3N4 still had a removal rate of 60% for ammonia nitrogen. The toxicity evaluation proved that EDTA-s-C3N4 was safe and non-toxic to zebrafish.
Conclusion EDTA-s-C3N4 has good removal effect on ammonia nitrogen in fish ponds. It is safe and non-toxic, and has good practicality.