Investigation of gel structure of aluminum hydroxycarbonate gel using a tension cell

A tension cell was designed to measure the gel structure of aluminum hydroxycarbonate gel. Equilibrium measurements of the total water outflow versus applied tension given insight into the rigidity of the gel structure. Dynamic measurements of the rate of outflow of water at various applied tensions yield the capillary conductivity of the gel, which is related to the apparent surface area, particle size, and porosity. An aluminum hydroxycarbonate gel with a high apparent viscosity exhibited an increase in viscosity upon aging at 25 degrees, which was accompanied by an increase in the equilibrium tension of the water phase, an increase in delta (-)GH2O, and a decrease in capillary conductivity. In contrast, the apparent viscosity of a low viscosity aluminum hydroxycarbonate gel, which was precipitated from the same reagents but with different precipitation temperature, pH, and stirring speed, exhibited a decrease in equilibrium water tension, a decrease in delta (-)GH2O, and an increase in capillary conductivity during aging at 25 degrees.