Chem. J. Chinese Universities ›› 2021, Vol. 42 ›› Issue (10): 3082.doi: 10.7503/cjcu20210147

• Analytical Chemistry • Previous Articles     Next Articles

Sampling of Ammonium Ion in High Salinity Waters Using Diffusive Gradients in Thin Films Technique

FENG Zhongmin, YANG Lan, SUN Ting()   

  1. Department of Chemistry,College of Sciences,Northeastern University,Shenyang 110819,China
  • Received:2021-03-04 Online:2021-10-10 Published:2021-10-10
  • Contact: SUN Ting E-mail:sun1th@163.com
  • Supported by:
    the National Natural Science Foundation of China(21777021)

Abstract:

Eutrophication is directly related to the concentration of ammonium ion. A new diffusive gradients in thin film(DGT) technique, using sodium cobalt hexacyanoferrate, was developed and evaluated for sampling ammonium ion in high salinity waters. Sodium cobalt hexacyanoferrate was prepared using double-dropwise addition method and characterized by means of SEM, XRD and nitrogen adsorption-desorption analysis. The adsorption rate and capacity for ammonium ion by sodium cobalt hexacyanoferrate and the effects of time, pH and co-existing ions on the sampling of ammonium ion by DGT devices based on sodium cobalt hexacyanoferrate were investigated. The adsorption process reached equilibrium after 60 min and was fitted well with pseudo-second-kinetic rate model. The adsorption capacity was 90.00 mg/g at the initial concentration of ammonium ion of 300 mg/L. Langmuir and Freundlich models could both fit well the adsorption behavior. The binding gel could be eluted by 1 mol/L KCl and the elution efficiency was 85.68%(n=6). The uptake mass of ammonium ion by DGT device as a function of time over 24 h demonstrated excellent linearity(r2=0.994). The uptake mass of ammonium ion was quantitative over pH range 4—8 and typical ion concentration ranges(up to Na+ 10000 mg/L, K+ 25000 mg/L, Mg2+ 20000 mg/L, Ca2+ 25000 mg/L). The results demonstrate that the DGT devices based on sodium cobalt hexacyanoferrate can accurately adsorb ammonium ion in high salinity waters.

Key words: Diffusive gradients in thin films technique(DGT), Ammonium ion, High salinity, Co-existing ion

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