Title

The influence of pulp and interfacial chemistry and mode of electrical power input on electroosmotic dewatering of Na-exchanged smectite dispersions

Document Type

Journal Article

Publisher

Elsevier

Place of Publication

Netherlands

School

School of Engineering

Comments

Originally published as: Harris, A., Nosrati, A., & Addai-Mensah, J. (2018). The influence of pulp and interfacial chemistry and mode of electrical power input on electroosmotic dewatering of Na-exchanged smectite dispersions. Applied Clay Science, 162, 214-222. Original article available here.

Abstract

In this study, pulp and interfacial chemistry, gravity settling/drainage and electroosmotic (EO) dewatering behaviour of two types of fine, Na-exchanged smectite clay (high and low Na content montmorillonites) slurries were investigated as a function of background electrolyte ionic strength and time at pH 7.5 with constant voltage (0.5 vs. 1 V/cm initial field strength) or current density (12.5 vs. 25 A/m2). The two smectite variants displayed significantly different mineral chemistry and particle zeta potential, the latter dependent on Ca(II) background. Suppressed swelling and marked reduction in zeta potential magnitude occurred at 0.03–0.3 M Ca(II) ionic strength, the extent of which was greater for low than high Na-smectite pulps. Ca(II) ionic strength of ~0.1 M improved pre-EO gravity dewatering from <5% to 70–80% water recovery for both low and high Na-smectite pulps. Low Na content clay, constant voltage input (1 V/cm initial field strength), 0.1 M Ca(II) and 8 h of operation were found to be most conducive conditions to EO efficacy in terms of minimising the energy consumed per kg water recovered. EO energy consumption of ~0.04–0.1 kWh/kg water recovered observed for 27–44 wt% additional water recoveries are competitive with the performance of conventional thermal and mechanical dewatering

DOI

10.1016/j.clay.2018.06.017

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