3.1.1 Effect of pH
Although PAHs exist as neutral molecules under ordinary conditions, pH plays a crucial role in the extraction process by affecting the charge species and density on the sorbent surface. Therefore, the effect of solution pH on PAH extraction was investigated by adjusting the pH from 2 to 13. However, no clear effect on PAH recovery was observed over the whole pH rang studied here, indicating that the adsorption of PAHs was not affected by the charges on the surface of the sorbents. Therefore, there is no need to adjust the pH of the sample solutions.