Preparation and performance characterization of ammonium ion sensitive bembrane based on PVC substrate
Ammonium ion selective electrode is an important component of ammonia nitrogen water detection sensor,and ammonium ion sensitive membrane is a key factor affecting electrode performance. Effects of plasticizers,ion additives,and ion carriers on response performance of ammonium ion selective electrodes were investigated,and the changes in performance parameters of the prepared electrode sensitive membrane were also explored,in which PVC was used as sensitive membrane substrate. The effects of 9 types of interfering ions such as Li+and Na+on electrode selectivity and anti-interference ability were also studied in this paper. The research results indicate that the optimal formula for the sensitive membrane is 50％DBP+0.75％ KTPClPB+1.20％ non bacterial agent. Mass ratio of the substrate PVC to DBP is 1∶1,and mass ratio to solvent (PVC∶THF) is about 1∶20. The lower detection limit of the sensitive film under this formula is 1.26×10-5 mol/L. When the concentration of ammonium chloride solution is greater than 10-3 mol/L,the response time is 0.5-2.0 s. While its concentration is less than 10-3 mol/L,the response time is extended to about 5s;The relative standard deviation of the reproducibility performance test is less than 2％,and the electrode life exceeds 90 days,indicating good performance. The characterization results such as XRD show that the membrane has an amorphous microstructure,and the good compatibility of each component is beneficial for enhancing the NH+4 response stability. After adding plasticizers and ionic additives,significant changes about main structure of the ion carrier are not appeared,which indicating integrity of the membrane. Selectivity coefficients of all 9 types of ions are less than 0,indicating that the interference is relatively small. Among them,K+interference is the largest,which can be solved by the proposed K+concentration correction equation,thereby improving the accuracy of ammonia nitrogen ion detection.
desulfurization wastewaterammonium ion selective electrodesensitive membraneplasticizerselectrode performance
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