Effects of inorganic sulfates on the microstructure and properties of ion-exchange treated palygorskite clay

► The structure and properties of sulfates modified palygorskite clay were investigated. ► Effects of sulfate type and loading on rheological, zeta-potential of clay were studied. ► The zeta-potential of treated samples followed the sequences: Al3+ < Zr4+ < Na+ < Zn2+. ► The shear modulus and viscosity of suspension improved after addition of 2.0% ZnSO4.