Effect of surfactant on zeta potential and rheology behavior of methylene bis(thiocyanate) suspension concentrate

Abstract Methylene bis(thiocyanate) (MBT) is insoluble in water, so suspension concentrate (SC) of MBT is extremely relied on surfactants. In this paper, SC of MBT was prepared with wet-grinding technology, and the effect of surfactants, such as Morwet D425 (D425) and Morwet EFW (EFW) (two kinds of dispersant), on the Zeta potential and rheology behavior of MBT SC were investigated. The results showed that the Zeta potential absolute value of MBT SC increased with the increasing content of D425, and it decreased with the increasing content of EFW at acidic solution (pH = 4.5). In the combination system of D425 and EFW, Zeta potential of MBT SC decreased first and then increased with the increasing content of EFW. The relationship between shear rate ( γ ) and viscosity ( η ) was studied according to Herschel–Bulkley model: η = η 0  +  k/γ, and the relationship between shear rate ( γ ) and shear force ( τ ) was investigated according to: τ = τ 0  +  Kγ n . It was revealed that the mixed fluid belonged to Yield Pseudoplastic Fluid.