Potassium Permanganate Doped Geopolymers for Remedial Applications

This study investigates the use of KMnO 4 doped geopolymers as controlled‐release materials for remedial applications. The geopolymers were prepared by mixing alkali activated Na‐silicate solutions, metakaolin, and various amounts of granular KMnO 4 . Samples were heat treated at 75 °C for 48 h. Concentrations of KMnO 4 in samples 1, 2, and 3 were 1.40 × 10 −1 , 4.63 × 10 −1 , and 6.07 × 10 −1  g/cm 3 , respectively. 1D column experiments showed that a high MnO 4 − release rate lasted for the first few hours, followed by a gradual decrease of MnO 4 − release. Neither cracks nor surface erosion of the geopolymers were observed throughout the experiments. Sample 1 approached exhaustion at the end of the Day 7. It took about 18 d for exhaustion of KMnO 4 releases in samples 2 and 3. Modeling of the observed KMnO 4 releases suggested diffusion and dissolution‐related fast transport as the most important mechanisms. This latter mechanism involves the creation of a connected secondary porosity in the geopolymers by dissolution of KMnO 4 granules. The contribution of Fickian diffusion to the total release decreased as the KMnO 4 content of the samples increased, and the dissolution mechanism became increasingly important.