Spicing up membrane distillation: Enhancing PVDF membrane performance with cinnamic acid

The increasing demand for freshwater is driving the rapid development of new water treatment materials. Furthermore, there is significant pressure to replace the toxic substances often used in membrane production with environmentally friendly, biocompatible, and natural compounds. In this work, poly(vinylidene fluoride) (PVDF) membranes were modified for the first time with a naturally occurring, non-toxic, biodegradable substance – cinnamic acid. The application of its molecules for membrane modification allows for diminishing the problem of bioaccumulation and toxicity in the environment. The procedure was selected with the accordance of green chemistry principles (green modifier – cinnamic acid, and green solvent – ethanol), and employed to chemically bind the modifier to the membrane surface. The modified membranes exhibited an increase in the hydrophobicity of the surface. The water contact angle increased from 124.7° for the pristine membrane to 139.3° for the membrane modified with a 10 % concentrated solution of cinnamic acid (PVDF-Cin10). All membranes possessed an excellent salt rejection coefficient. Membrane antiwetting features have been determined under challenging conditions of salt (3 M NaCl) and low surface tension liquid (sodium dodecyl sulfate). The dynamic goniometric studies were implemented to evolve membranes' wetting stability.