## 3 Results  
### Drying of Granules  
A sample of 5 grams of ODTMA- or BDMHDA-clay granules was subjected to the MW irradiation for 90 s, 180 s, 270 s, 360 s, and 450 s. After each duration, sample mass was measured. The sample was then immediately placed in the MW oven for another duration. After 360 s of MW irradiation of ODTMA-clay sample, mass loss was about 2.3% (Figure 1). Mass losses of BDMHDA-clay were essentially similar, and will be discussed later. It has been observed [14; 15] that MW heating causedlarger mass losses in several clays and organo-clays than conventional heating. MW heating makes it possible to easily remove weakly bound water molecules. These water molecules are weakly retained between the surfactant ion layers as previously explained [16]. In addition, the moisture in the surface is easily removed by MW. In the current study, after about 6 min of MW heating the complexes started to deteriorate.  
Results of drying of granules based on ODTMA and BDMHDA in a conventional oven at 60 \({}^{\circ}\)C yielded after 30 min removal of \(0.2\pm 0.1\) g water from 32 g granules (including 3% humidity) to which 1 g of water had been added. A larger removed amount of \(0.9\pm 0.1\) g water was observed by MW heating for 90 s of ODTMA-clay granules (whose temperature was 145 \({}^{\circ}\)C). A smaller loss of \(0.6\pm 0.1\) g was observed for BDMHDA-clay granules (at 135 \({}^{\circ}\)C).  
The results (Table 1) indicate that in comparison to an ordinary oven, removal of water was achieved by the MW oven within about a 20-fold shorter time. It is noted that the ordinary oven was operated at a maximum of 800 W, whereas the MW was operated at 700 W.  
The results in Table 2 demonstrate that MW heating removed water more efficiently from ODTMA-clay granules than from BDMHDA-clay granules whose critical micelle concentrations are 0.3 and 0.6 mM, respectively. This result is consistent with the outcome that the magnitude of free energy of interaction of ODTMA cations with the clay surface exceeds that of BDMHDA cations. This was seen by the smaller extent of release of ODTMA cations from the complex than that of BDMHDA cations in suspension [17] and during filtration [8]. It can be rational  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \multicolumn{3}{c}{**Conventional Oven 1  } & \multicolumn{3}{c}{**MW Oven **} \\ \hline
**Time (h)** & **Granules (g)** & **Time (min)** & **Granules (g)** & **Granules (g)** \\ \hline
0.0 & 61.5 & 92.3 & 123.1 & 0.0 & 61.5 & 92.3 & 123.1 \\
0.5 & 57.1 2  & 84.7 & 111.8 & 5.0 & 41.2 2  & 69.7 & 100.4 \\
1.0 & 52.2 & 79.5 & 110.2 & 7.0 & 39.3 & 64.3 & 87.3 \\
1.5 & 45.7 & 71.0 & 102.1 & 8.0 & - & 62.3 & 80.6 \\
2.0 & 40.0 & 64.1 & 88.1 & 9.0 & - & 60.0 & 79.8 \\
2.5 & - & 59.8 & 84.7 & - & - & - & - \\of more water molecules reduces the magnitude of the interaction between the organic cations and the surface sites.  
In the following experiments the MW oven was operated at 700 W and drying of granules with a water content of 5% to 40% was studied. The results (Table 3) demonstrate that at a humidity of less than 30%, a sharp increase of temperature and the ignition point of the material was reached. By reducing the heating time from 2 min to 1 min (or less), the ignition could be avoided.