Mixed adsorption of ionic and non-ionic surfactants on calcium carbonate

Abstract The adsorption of dodecylamine hydrochloride (DDAHC) and polyoxyethylene (20) sorbitan monolaurate (Tween-20) from their single aqueous solutions and from DDAHC—Tween-20 mixed binary solutions on calcium carbonate at 20°C has been investigated. The results show that individual cationic surfactants can be adsorbed on the negatively charged surface of calcium carbonate, leading to a change in the sign of the zeta potential of the calcium carbonate particles to positive. The adsorption of non-ionic surfactants reduces the zeta potential to zero. However, no significant adsorption of DDAHC from mixed binary DDAHC Tween—20 solutions can be detected. The adsorption of Tween-20 from mixed binary solutions decreases when the concentration of DDAHC in the mixture increases. Intensive flocculation of the calcium carbonate particles is found in all the mixed solutions.