Cellulose nanocrystal-mediated synthesis of silver nanoparticles via microwave assisted method for biofouling control in membrane distillation

Biofouling in membrane distillation (MD) severely impacts the process performance and significantly reduces membrane lifespan. Herein, polyvinylidene fluoride (PVDF) membrane was modified with silver nanoparticles (AgNPs) embedded on cellulose nanocrystals (CNCs), mainly to improve their antibacterial properties. The synthesis of CNC-capped AgNPs was conducted via microwave assisted methods, where CNCs acted both as reducing and capping agents of AgNPs. Transmission electron microscopy (TEM) confirmed the successful synthesis of unevenly distributed AgNPs, markedly exhibiting an average diameter of 13.3 +/- 3.94 nm. The antibacterial activity of CNC-capped AgNPs was assessed via minimum inhibitory concentration (MIC). Embedment of CNC-capped AgNPs on the PVDF membrane was performed via the phase-inversion technique, where tap water was used as coagulating agent. Evaluation of the antibacterial activity of pristine PVDF and CNC/AgNP-modified PVDF membrane was assessed via disc diffusion and cell viability. Five different strains of bacteria were tested including Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus, Staphylococcus epidermis and Staphylococcus saprophyticus. In comparison to unmodified PVDF membrane, the CNC/AgNPmodified PVDF membrane exhibited strong antibacterial activity, largely because of a decrease in the number of live cells (up to 98 %) following contact with the modified membrane. These results indicate the potential application of CNC/AgNP-modified PVDF membrane toward mitigation of biofouling in MD and other membrane-based water purification processes.