Stepwise complexometric determination of aluminium, titanium and iron concentrations in silica sand and allied materials

Nijhuma Kayal,Nahar Singh

doi:10.1186/1752-153x-1-24

Abstract

BackgroundThis study aimed at measuring the quantities of Al, Ti and Fe in silica sand and allied materials employing a complexometric method in the same analyte and a stepwise indirect titration with EDTA. The method involves the complexation of Al, Ti and Fe with excess EDTA and the selective de-complexation of TiO-EDTA and Al-EDTA complexes with tartaric acid and NaF respectively. In addition to its simplicity, rapidity and accuracy, the proposed method does not require the use of a separation technique or any sophisticated instrumentation.ResultsEach of the test samples were analyzed five times using the proposed method. The method's accuracy was confirmed by analyzing the US National Institute of Standards and Technology's (NIST) Standard Reference Materials (SRM) 81a, 89 and IPT SRM 61 using the procedure proposed, in addition to analyzing Ti and Fe levels by spectrophotometry and that of Al by complexometry.ConclusionThe study shows that there is good agreement between the proposed and existing methods. The standard deviations of the measurements were calculated by analyzing five replicates of each sample, and were found to be less than 1.5% in our method.

Highlights

This study aimed at measuring the quantities of Al, Ti and Fe in silica sand and allied materials employing a complexometric method in the same analyte and a stepwise indirect titration with EDTA
The quantities of Fe and Al are determined by complexometry, while that of Ti is determined by spectrophotometry after Ti(OH)4 has dissolved
It has been observed that EDTA released on the addition of tartaric acid should be titrated under hot conditions, because at room temperature EDTA is released partially and poor results are obtained

Summary

Introduction

This study aimed at measuring the quantities of Al, Ti and Fe in silica sand and allied materials employing a complexometric method in the same analyte and a stepwise indirect titration with EDTA. Silica sand is a white or colourless crystalline compound, occurringabundantly as quartz, sand, flint, agate and in many minerals [1]. It is used as an essential raw material in the production of glass, foundry, abrasives, filters, ceramics, in chemical and hydraulic fracturing and on oil fields [2]. The quantities of Fe and Al are determined by complexometry, while that of Ti is determined by spectrophotometry after Ti(OH) has dissolved This method has the disadvantage that Fe is co-precipitated when present in large amounts

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