Use of polymer as template in microwave synthesis of saponite. Study of several factors of influence

•Delaminated saponites were prepared at pH 8 at different dilutions and with polymer.•Higher slurry concentration favored order in the tetrahedral sheet and purity.•H2O/Si = 125 led to the saponite with the best AlT/AlO ratio, C.E.C. and BET area.•The effect of polymer depended on the heat source and the slurry dilution.•The presence of polymer improved order in the tetrahedral sheet and purity.

Several saponites were synthesized at pH = 8 by microwaves or conventional hydrothermal aging with different slurry dilutions (H2O/Si molar ratios of 250, 125 and 50) at 453 K under autogenic pressure. The influence of using a polymer as template, during the synthesis, and its molecular mass was investigated. The saponite prepared with medium dilution slurry by microwaves had the best incorporation of Al3 + in tetrahedral positions (AlT/AlO = 9.2), in agreement with its highest C.E.C. (0.87 mEq/g). Additionally, this sample showed the highest surface area (461 m2/g). In general, the increase of the slurry concentration and the presence of polymer improved the order in the tetrahedral sheet and decreased the amorphous silica content. The effect of polymer, on the stacking, was low but depended on the dilution and heat source (microwaves or conventional). The use of polymer and its molecular mass modified the saponite porosity and the incorporation of Al3 + in the tetrahedral sheet.