کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
612742 880705 2006 4 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
The impact of ionic strength and background electrolyte on pH measurements in metal ion adsorption experiments
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی شیمی کلوئیدی و سطحی
پیش نمایش صفحه اول مقاله
The impact of ionic strength and background electrolyte on pH measurements in metal ion adsorption experiments
چکیده انگلیسی

Our understanding of metal ion adsorption to clay minerals has progressed significantly over the past several decades, and theories have been promulgated to describe and predict the impacts of pH, ionic strength, and background solution composition on the extent of adsorption. Studies evaluating the effects of ionic strength on adsorption typically employ a broad range of background electrolyte concentrations. Measurement of pH in these systems can be inaccurate when pH values are measured with liquid junction pH probes calibrated with standard buffers due to changes in the liquid junction potential between standard, low ionic strength (0.05 M) buffers and high ionic strength solutions (>0.1 M). The objective of this research is to determine the extent of the error in pH values measured at high ionic strength, and to develop an approach for accurately measuring pH over a range of ionic strengths using a combined pH electrode. To achieve this objective, the adsorption of cobalt (10−5 M) onto gibbsite (10 g/L) from various electrolyte solutions (0.01–1 M) was studied. The pH measurements were determined from calibrations with standard buffers and ionic strength corrected buffer calibrations. The results show a significant effect of the aqueous solution background electrolyte anion and ionic strength on pH measurement. The 0.5 and 1 M ionic strength metal ion adsorption edges shifted to lower pH with increasing ionic strength when pH was calibrated with standard buffers whereas no shift in the adsorption edges was observed when calibrated with ionic strength corrected buffers. Therefore, to obtain an accurate pH measurement, pH calibration should contain the same electrolyte and ionic strength as the samples.

Adsorption edge data shifts to lower pH (the left) when pH measurements are calibrated with standard buffers (□, ○). When calibrated with ionic strength corrected buffers (■, ●) they align with low ionic strength data (▴, —).Figure optionsDownload as PowerPoint slide

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Colloid and Interface Science - Volume 301, Issue 1, 1 September 2006, Pages 329–332
نویسندگان
, , ,