Jeong Hwan Chun

Novel thin nanocomposite RO membranes for chlorine resistance

Abstract Sulfonated poly(arylene ether sulfone) material containing amino groups (aPES) is successfully synthesized using aromatic substitution polymerization. This material was shown to be a novel thin-film composite (TFC) reverse osmosis (RO) membrane material with high chlorine resistance. Graphene oxide (GO) and aminated graphene oxide (aGO) nanoparticles were also prepared. TFC membranes were prepared using an interfacial polymerization (IP) reaction with trimesoyl chloride (TMC) and amine solution, containing synthesized materials, on a polysulfone (PS) ultrafiltration (UF) support membrane. The synthesized aPES and fabricated TFC RO membranes were characterized by nuclear magnetic resonance spectroscopy and scanning electron microscope. Moreover, RO performances, salt rejection, and water flux were measured using cross-flow cell instrument. The chlorine resistance was evaluated using sodium hypochlorite solution. The membrane fabricated with aPES/GO/aGO was compared with the typical polyamide (PA) ...

Composite membranes based on sulfonated poly(ether ether ketone) and SiO 2 for a vanadium redox flow battery

Organic-inorganic composite membranes were prepared with sulfonated poly(ether ether ketone) (SPEEK) and different amounts of silica to improve chemical stability and vanadium hindrance for a vanadium redox flow battery. The durability of the prepared composite membrane was verified using a self-made dummy cell system and fully charged vanadium cathode half-cell electrolyte, which contained oxidative vanadium ions (VO2+). The prepared composite membranes, with covalent crosslinking between the organic polymer and inorganic particles, resulted in reduced vanadium permeability and enhanced chemical stability. Ion exchange capacity, water uptake, proton conductivity, and vanadium permeability decreased with increasing silica content. Selectivity was defined to consider both permeability and proton conductivity and resulted in a membrane that exhibited both high proton conductivity and low ion permeability simultaneously. The prepared 1 wt% silica composite membrane showed 133-fold higher selectivity compared with that of a Nafion112 membrane. After the stability test, the composite membrane showed little change compared to the membrane before the stability test, which confirmed the commercial prospect of SPEEK/SiO2 composite membrane for a vanadium redox flow battery.

Fabrication and characterization of the chlorine-tolerant disulfonated poly(arylene ether sulfone)/hyperbranched aromatic polyamide-grafted silica composite reverse osmosis membrane

Abstract In this study, hyperbranched aromatic polyamide-grafted silica (HBP-g-silica) and disulfonated 4,4-bis(3-aminophenoxy)phenyl sulfone (aPES) composite membrane was prepared to enhance the chlorination resistance of reverse osmosis (RO) membrane for desalination process. As the commercial polyamide (PA) RO membrane is very weak against free chlorine in desalination process, inorganic nanoparticle and new membrane material were introduced to RO membrane’s active layer. The HBP-g-silica which includes lots of PA chains on the surface of silica and the new material aPES for RO membrane were characterized by 1H-NMR and Fourier transform infrared spectroscopy (FT-IR). The surface morphology of synthesized RO membrane was characterized by scanning electron microscope, and the performance, salt rejection, and water flux were evaluated before and after chlorination test. After the chlorination test, salt rejection was decreased by 36.2% and water permeation was increased only by 5.6% compared to the perfor...

Novel thin-film composite membrane for seawater desalination with sulfonated poly(arylene ether sulfone) containing amino groups

Abstract Sulfonated poly(arylene ether sulfone) containing sulfonic acid and amino groups (SDADPS) were successfully synthesized using direct-step polymerization as a novel thin-film composite (TFC) reverse osmosis (RO) membrane material for high chlorine resistance. TFC membranes were prepared using an interfacial polymerization (IP) reaction with trimesoyl chloride (TMC) and amine solution, containing m-phenylenediamine (MPDA) and SDADPS, on a polysulfone (PS) ultrafiltration (UF) support membrane. The synthesized SDADPS and fabricated TFC RO membranes were characterized by nuclear magnetic resonance spectroscopy and scanning electron microscope. Moreover, RO performances, salt rejection and water flux, were measured using a cross-flow cell instrument. Chlorine resistance was evaluated using sodium hypochlorite solution. The membrane fabricated with SDADPS was compared with a typical polyamide (PA) TFC membrane which was prepared by IP reaction with TMC and MPDA on a PS support membrane. The SDADPS RO m...