Filtration of oil from oily wastewater via hydrophobic modified quartz sand filter medium

To improve the hydrophobicity and lipophilicity of a quartz sand filter medium, two coupling agents, DN101 and KH570, were employed. The filter medium surface wettability and oil removal efficiency before and after modification were investigated, and the characteristics are summarized. The test results show that, after modification by the grafting of an organic long-chain coupling agent to the filter medium surface, the lipophilic to hydrophilic ratio increased from 1.31 (UQS) to 12.09 (MQD-Ti) and 5.11 (MQD-Si), and the oil removal efficiencies of MQD-Ti and MQD-Si improved by 21.7% and 6.9%, respectively. The stronger hydrophobicity resulted in higher quality factor values of 0.668 m(-1) and 0.548 m(-1) for MQD-Ti and MQD-Si, respectively, compared to 0.533 m(-1) for UQS. This means that improving the filter medium surface hydrophobicity and oil removal efficiency via filter medium surface modification is effective.