Capacitive deionization and disinfection of water using graphene oxide-dendrimer-silver coated electrodes

Abstract

This study is aimed to explore highly efficient water desalination and disinfection using a new capacitive deionization (CDI) system. The novel nanocomposite based on graphene oxide was synthesized and grafted five generations of dendrimer and silver nanoparticles; subsequently, the CDI electrodes were coated by the new nanocomposite. The introduced nanocomposite was characterized using Fourier-transform infrared spectrometry, thermogravimetric analysis, Brunauer–Emmett– Teller surface area analysis, surface wettability, and field emission scanning electron microscopy. Different affecting parameters, including total dissolved solids (TDS) (500–20,000 mg L–1), number of coliforms (500–100,000 MPN), different amounts of silver nanoparticles (0.2% and 5%), and contact time (15–120 min) were evaluated. The new electrodes can be converted to TDS from 20,000 to 400 mg L–1. Thus, the new electrodes with an electrosorption capacity of 46.29 mg g−1 presented 98% ion removal in saltwater treatment. The CDI system can also kill 99.9% of coliforms in the NaCl solution (500 mg L–1) containing 1,000; 10,000; 100,000 MPN of coliforms within 30, 60, and 120 min, respectively. Moreover, the coliform removal performance was successful in high TDS water (5,000 mg L–1). The new nanocomposite indicated high adsorption/desorption capacity in alternating cycles and regeneration quickly, which makes it an excellent candidate in the continuous process.