Adsorption of organic surfactants to clay minerals has an effect on the electrical double layer interactions and on the Van der Waals interactions [1-3]. They alter the electro kinetic properties (mobility and zeta potential) and filtration behavior

The present work aims to investigate the effect of sulphanilamide (SA) adsorption on the zeta potential and water loss of raw local bentonite (B) and Na-bentonite (Na-B) suspensions. This was accomplished by separating the fine particles of raw bentonite of size (< 1μm), then activating them by Na+ ions. Adsorption isotherms of SA on B and Na-B were obtained at different SA concentrations ranging from (10–1000 mg/L) using the batch-equilibrium technique. It was found that the adsorbed amount of SA onto B and Na-B increased with increasing SA concentration. The zeta potentials of B and Na-B suspensions (1% w/v) were measured and correlated with the adsorption data. The zeta potentials of B and Na-B suspensions decreased to comparable values with increasing SA concentrations. Moreover the water loss of B and Na-B suspensions decreased with increasing SA concentrations reaching minimum comparable values then increased with increasing SA concentration. The adsorption of SA did not influence the zeta potential and water loss of B and Na-B suspensions. Thus raw local bentonite may be used without treatment in many industrial applications. Index Term-_Sulphanilamide; Raw local bentonite; Nabentonite; Zeta potential; Water loss; Adsorption.