Study on the adsorbing performance of ammonia nitrogen by polyacrylic acid-grafted sodium alginate-based titanium dioxide(PAA/SA@TiO2)composite hydrogel
The polyacrylic acid-grafted sodium alginate-based titanium dioxide(PAA/SA@TiO2)composite hydrogel showed excellent adsorption performance for ammonia nitrogen.The optimal adsorption conditions is pH=7,T=35℃,adsorbent dosage 6 g·L-1 and adsorption equilibrium time of 70 minutes.At that time,the adsorption efficiencies were 85.56%,79.46%and 67.63%for initial ammonia nitrogen concentrations of 100,200 and 300 mg·L-1,respectively.The adsorption process is the Langmuir model of monolayer adsorption,and the adsorption kinetics belongs to the pseudo-second-order kinetics model of chemical adsorption.Thermal gravimetric analysis(TGA)showed that the main chain,hydroxyl and carboxyl groups,of PAA/SA@TiO2 composite hydrogel began disrupting and degrading at 446℃with thermal loss rate of 48%at 800℃.The PAA/SA@TiO2 composite hydrogel possessed a stable structure,and the adsorption efficiency only decreased by approximately 10%after 5 cycles of adsorption and regeneration.The research indicated that the PAA/SA@TiO2 composite hydrogel had great potential in the nitrogen-containing wastewater treatment.The results provided theoretical basis and operational parameters for the application of hydrogels.
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