Separating Nanoclay Minerals via Electrophoretic Deposition

Abstract

This paper presents the possibility of separating nanoclays from aqueous synthetic slurry of two clays by EPD. Na-Montmorillonite (NM) from Southern Clay Products and kaolinite (K) from Source Clays Repository were used at 2:1 weight ratio at 3.5% solid loading for making the synthetic slurry. Effect of applied potential [2 and 4V] and electrode gaps [1 and 2centimeters] was investigated on the yield and on the NM/K ratio of the deposit. Stainless steel was used for working and counter electrodes. AUTOLAB (pgstat302N) was used in the conduct of EPD. Open circuit potential of the slurries was used as reference potential for EPD. Slurries were stirred at constant rate of 300 rpm during EPD for twenty minutes. Shimadzu XRD-7000 was used to determine NM/K ratio of the dried deposit. ANOVA of two-factor fixed effect Model was employed with F-test at 5% significance level.NM slurries have negative bulk potential [163-170 mV], while positive bulk potential to kaolinite slurries. NM slurries had higher bulk conductivities [1.616 mS/cm] and pH [~10.2] than kaolinite slurries. These distinct slurry properties could lead to their differential electrophoresis during EPD. Effect of the interaction of applied potential and electrode gap for the yield and the NM/K ratio was significant. High potential [4V] - low electrode [1cm] gap had the highest yield of deposit. NM/K ratios of the deposits were compared to the clay ratio of the synthetic slurry. High potential [4V]–high electrode [2cm] gap showed highest NM/K ratio at an average of 5.2 :1 from 2:1. This means Na-MMT has been successfully separated from kaolinite from aqueous synthetic clay slurry by EPD at specific potential – electrode gap combination.