**4. Conclusions**

Nanofiltration membranes including capsaicin were prepared and characterized through contact angle measurements, AFM, ATR infrared spectroscopy and cross-flow tests. The ATR infrared spectroscopy showed that capsaicin reacted with the TMC, forming a new covalent link, which did not exist in the control membrane without capsaicin. In addition, AFM imaging showed that the surface of membranes with capsaicin in the active layer presented reduced roughness compared to the control membrane.

The results presented in this chapter show that capsaicin-based composite membranes present higher hydrophilic characteristics than traditional composite membranes. These properties of the capsaicin molecule can be attributed to its hydroxyl and amide groups, resulting in affinity to water. The hydrophilic character of the membranes with capsaicin was also reflected higher water permeability by the membranes.

It was also found that higher hydrophilicity and permeability could mostly be attributed to capsaicin present on the active layer of the membranes. This is because the presence of capsaicin in the porous membrane support layer did not show significant flux increases. Although capsaicin in the porous support increased salt rejection, we concluded that the application of capsaicin on the support layer of the membrane is not necessary. It is expected that nanofiltration membranes with capsaicin will result in better anti-biofouling properties than typical commercial membranes and, therefore, their service life would be longer. Future work will test this hypothesis.
