کد مقاله | کد نشریه | سال انتشار | مقاله انگلیسی | نسخه تمام متن |
---|---|---|---|---|
1172121 | 960747 | 2006 | 6 صفحه PDF | دانلود رایگان |
عنوان انگلیسی مقاله ISI
Acid-base properties of silica-based ion-exchanger having covalently bonded aminodi(methylphosphonic) acid
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موضوعات مرتبط
مهندسی و علوم پایه
شیمی
شیمی آنالیزی یا شیمی تجزیه
پیش نمایش صفحه اول مقاله
![عکس صفحه اول مقاله: Acid-base properties of silica-based ion-exchanger having covalently bonded aminodi(methylphosphonic) acid Acid-base properties of silica-based ion-exchanger having covalently bonded aminodi(methylphosphonic) acid](/preview/png/1172121.png)
چکیده انگلیسی
Acid-base properties of an organophosphorous silica-based ion-exchanger with covalently bonded complexone groups-N-propylaminodi(methylphosphonic) acid (AdPA-SiO2) were studied. By comparison of AdPA-SiO2 chemical analysis and data of pH and conductometric titration it was demonstrated that the composition of immobilised layer differ from sample to sample and might consist of 60-88% aminodi(methylphosphonic) acid and 12-40% of residual aminopropyl groups. Regardless of the multifunctional nature of AdPA-SiO2 interfacial layer, its acid-base properties can be predicted. All studied AdPA-SiO2 samples have the properties of strong multiprotic H4L acids with pK1 < 2.6. Incomplete transformation of amino groups to aminodiphosphonic acid plays the key role in determination of the conditions of AdPA-SiO2 ionisation in neutral and weak-basic media. Linear correlation was found for pK2 and amine-to-acid conversion degree (Ï) with pK2 = 8.8 â 4.0Ï. It allows us to determine the conditions of AdPA ionisation for all AdPA-SiO2 samples. The established correlation can be used to check the quality (the degree of interfacial layer heterogeneity) of AdPA-SiO2. The final measurable ionisation constant for AdPA-SiO2, pK3 = 7.9 ± 0.6 is 2-orders of magnitude higher then acidity constant for AdPA homogeneous analogue. It seems that such reduction is caused by increase of electro static interaction between movable counter-ions and negatively charged surface groups. Conductometric study of AdPA-SiO2 also suggests firm fixation of counter-ions in the interfacial layer.
ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Analytica Chimica Acta - Volume 565, Issue 2, 21 April 2006, Pages 157-162
Journal: Analytica Chimica Acta - Volume 565, Issue 2, 21 April 2006, Pages 157-162
نویسندگان
V.N. Zaitsev, L.S. Kostenko, N.G. Kobylinskaya,