## 3 Results
### Thermogravimetric Analysis  
Figure 5 shows thermogravimetric analysis of ODTMA-clay samples. The first decomposition step is related to the mass loss of adsorbed water and gaseous species (\(<\)150 \({}^{\circ}\)C). The lowest mass loss was observed in MW heated samples (0.31%, at 100 \({}^{\circ}\)C) with respect to other samples. Mass loss in the sample not subjected to MW heating (MW free) was 1.53 percent. The weakly bound water molecules in the pores between the interlayer ODTMA ions are expected to be the first target of the energy that the MW will use for the dipole orientation. As a result of the large magnitude of the energy of dipole orientation, which is the basis of dielectric heating, gaseous species and weakly bound water molecules were apparently detached. In the MW heated sample, the observation of low mass loss indicates that weakly bound water between the organic molecule and the clay surface did not form pores again after heating. As a result, MW heating increased the level of hydrophilicity of organo-clay.  
Onset temperatures were shifted to the lower values by MW heating. A low temperature endothermic peak was observed at 65 \({}^{\circ}\)C for the MW free sample. The endothermic peak observed in natural bentonite at around 100 \({}^{\circ}\)C has been reported to shift to 70 \({}^{\circ}\)C in organic bentonite [15]. It was noted that MW heating is an internal process [23].  
The second region in TGA curves (150-550 \({}^{\circ}\)C) is associated with the organic substances. In this region, the surfactant begins to decompose [15]. The initial decomposition temperature of ODTMA is 272 \({}^{\circ}\)C for a MW free sample. In MW heated samples, this temperature decreased to 264 \({}^{\circ}\)C. In the process of removing the impurities in the organo-clay used in water filtration and inactivation of bacteria, MW heating would be sufficient. In the second part of the dehydration stage (120-200 \({}^{\circ}\)C), elimination of adsorbed water still remains effective up to 200 \({}^{\circ}\)C [18]. The secondary thermal degradation step (420 \({}^{\circ}\)C) could be attributed to the desorption of surface hydration water, the loss of structural hydroxyl groups, and a crystal phase change [14; 24]. Although this temperature step did not change in the case of the MW free sample (420 \({}^{\circ}\)C), the MW heated sample showed slight variations (417 \({}^{\circ}\)C). Thus, a small portion of the mass loss in this region is due to the removal of water and the majority of the mass loss is due to the decomposition of the surfactant. In this region, MW heating processes resulted in high mass loss compared to the ODTMA clay sample (MW free sample).  
The third region, which is called dehydroxylation of clay (structural water), is between 550 and 700 \({}^{\circ}\)C [15; 18; 25; 26]. In the MW heated sample, the mass loss did not change significantly compared to the ODTMA clay sample (MW free sample).  
The corresponding results for BDMHDA-clay are similar to those of Figure 5a,b, particularly in the range of temperatures up to 150 \({}^{\circ}\)C. For the sake of completeness, these results are presented in Figure S1a,b.