Adsorption properties for ammonia nitrogen by polyacrylic acid/sodium alginate-based titanium dioxide composite hydrogel

• Published in: Desalination and water treatment 2023-12, Vol.316, p.383-394
• Main Authors: Guo, Chang-Zi, Han, Yi, Zhao, Wan-Qin, Xu-Li
• Format: Article
• Language: English
• Subjects: Adsorption mechanism; Ammonia nitrogen; Composite hydrogel; Performance characterization; Recycling
• ISSN: 1944-3986
• DOI: 10.5004/dwt.2023.30208

Polyacrylic acid/sodium alginate-based titanium dioxide (PAA/SA@TiO2) composite hydrogel has the good nitrogen removal properties in the nitrogen-containing wastewaters. Under the optimal adsorption conditions, which include pH 7, temperature 35°C, adsorbent dosage 6 g/L, adsorption equilibrium time 70 min, the adsorption efficiency is 85.56%, 79.46%, and 67.63% when the initial ammonia nitrogen concentrations of 100, 200, and 300 mg/L, respectively, indicating that the hydrogel has good adsorption performance for ammonia nitrogen. The adsorption process conforms to the monolayer adsorption of the Langmuir model, and the adsorption kinetic process belongs to the pseudo-second-order kinetic model of chemical adsorption. The structure of PAA/SA@TiO2 composite hydrogel is stable. The thermogravimetric analysis revealed that its main chain of the composite hydrogel began to break and degrade only at 446°C with thermally decomposed hydroxyl and carboxyl groups. At 800°C, the thermal loss rate was 48%. After 5 cycles of adsorption regeneration, the adsorption efficiency only drops by about 10%. The research results showed that PAA/SA@TiO2 composite hydrogel had great application prospects in the field of nitrogen-containing wastewater treatment, which provided the theoretical basis and operating parameters for the hydrogel applying in the nitrogen-containing wastewaters treatment.