Antifouling performance of spiral wound type module made of carbon nanotubes/polyamide composite RO membrane for seawater desalination

Abstract

Robust nanocomposite reverse osmosis (RO) module was assembled using crosslinked polyamide (PA) and carbon nanotubes (CNT) membranes, and their fouling resistance in real seawater desalination conditions was evaluated. The CNT-PA nanocomposite membrane was used to build a 2 in. and 4 in. RO module. The modules were tested for fouling in the laboratory using bovine serum albumin (BSA) dissolved in simulated seawater. The synthesis of the crosslinked CNT polyamide structure resulted in a lower foulant interaction and high salt rejection rates (99.87 wt%). The RO-laboratory scaled modules showed excellent antifouling behavior compared with commercial antifouling membranes, maintaining a continuous operation without substantial pressure drop variations. Pilot-plant tests with real seawater were performed at the water plaza facility, Kitakyushu city, Japan. A RO industrial vessel built with CNT-PA nanocomposite modules showed superior antifouling performance with a stable operation for more than 100 days due to changes in surface charge and superficial fouling blocking. In contrast, antifouling commercial vessel showed 2.3 times higher foulant deposition. These CNT-PA nanocomposites RO antifouling modules for uninterrupted operation performance are ideal for desalination plants because they require less operation maintenance than commercial membranes, promoting green desalination technology, which is becoming increasingly important due to current environmental concerns.