Preparation of a new lignosulfonate-based thinner: introduction of ferrous ions

In developing a new lignosulfonate-based thinner for bentonite mud formulations, ferrous ions (Fe2+) were introduced. With the increase of Fe2+ amount introduced in the synthesis, the adsorption amount of the prepared samples on the bentonite increases obviously and then has a decrease, and the opposite holds true for the main rheological parameter values (apparent viscosity, plastic viscosity and yield point) of the treated bentonite mud. The improved adsorption and thinning abilities could result from the bridging of chelated Fe2+ between the modified lignosulfonate molecule and the bentonite surface, and the decreased adsorption and thinning properties may be attributed to the molecular shrinkage of Fe2+-chelated lignosulfonate derivative. On the basis of the results obtained, the optimum Fe2+ amount was found.