Surface chemical and selective flocculation studies on iron oxide and silica suspensions in the presence of xanthan gum

The changes in the surface chemical properties of iron oxide and silica suspensions consequent to the addition of xanthan gum were studied. The adsorption density of xanthan gum for iron oxide was found to be maximum at pH similar to 2, whereas almost nil adsorption was found for silica throughout the pH range investigated. The isoelectric points (i.e.p.) of iron oxide and silica were found to be located at pH similar to 8.4 and presumably less than pH 2 respectively. The addition of xanthan gum shifted the i.e.p. of iron oxide towards more acidic pH values, in proportion with the concentration of xanthan gum added, with a concomitant change in the zeta potentials to more electronegative or less electropositive values. The maximum flocculation of iron oxide (98%) was observed in the wide pH regime of 2-9 with the optimum dosage of xanthan gum (20-50 ppm). The electrokinetic and flocculation characteristics of the silica were not altered much by the addition of xanthan gum, akin to the adsorption result. FTIR spectral investigations provide evidence in support of hydrogen bonding and chemical interaction forces between iron oxide and xanthan gum. Maximum separation efficiency of 65% for iron oxide-silica mixture was observed in selective flocculation tests.

Automated summary

The study showed that the addition of xanthan gum altered the isoelectric point and zeta potential of iron oxide suspensions, while having little effect on the electrokinetic and flocculation characteristics of silica. Additionally, FTIR spectral investigations provided evidence of hydrogen bonding and chemical interaction forces between iron oxide and xanthan gum, leading to a maximum separation efficiency of 65% for iron oxide-silica mixture in selective flocculation tests.