Adsorption Performance of Modified Zeolite Granulation on Ammonia Nitrogen

A nitrogen removal granular material (MZ) was prepared from modified zeolite with the addition of polyvinyl alcohol (PVA) and sodium bicarbonate (NaHCO₃), and the effects of factors such as the dosage and pH on the adsorption performance of ammonia nitrogen (NH₄⁺-N) were investigated. The results showed that the removal rate of NH₄⁺-N by MZ was 94.0% under the conditions of MZ dosage of 5 g/L and initial pH of 7. The adsorption process of NH₄⁺-N by MZ was in accordance with the quasi-secondary kinetic model and Freundlich adsorption isotherm model, and this process was jointly affected by liquid film diffusion and intra-particle diffusion, and the saturated adsorption amount of NH₄⁺-N was 8.47 mg/g. The four common cations showed inhibitory effects on the adsorption of NH₄⁺-N by MZ in the order of K⁺ > Na⁺ > Ca²⁺ > Mg²⁺. After five cycles of regeneration, the MZ could still maintain more than 80% of NH₄⁺-N removal. Combined with the analytical results of material characterization, the adsorption of NH₄⁺-N by MZ is mainly due to chemical adsorption based on ion exchange, while physical adsorption contributes less.