Advances in Hollow‐Fiber Reverse‐Osmosis Membrane Modules in Seawater Desalination

Cellulose Triacetate (CTA) Hollow-Fiber (HF) Membranes for Sustainable Seawater Desalination: A Review

“…The RO process was firstly proposed by Reid of Florida University in the beginning of 1953 [ 23 , 36 ]. After then, the workers at Florida University announced a cellulose diacetate (CDA) film with outstanding semipermeable performance in which salt rejection was 96% or more, but its water permeability was still very small and not applicable for commercial application [ 37 , 38 ]. However, their pioneering work clearly showed a possibility of conducting a RO process using a semipermeable membrane for seawater desalination.…”

“…After this invention, accelerated research on cellulose-acetate (CA)-based materials for practical applications was conducted to improve the membrane performance in the industry [ 41 ]. The details in the early history of RO membrane development are available elsewhere [ 37 , 41 , 42 , 43 , 44 , 45 ]. As CA-based polymers, cellulose triacetate (CTA) [ 46 ], cellulose acetate butylate [ 47 ], CA blends such as CDA with CTA [ 45 , 48 ], the cross-linked CA [ 49 ], and the composite membrane (a thin CA film on a porous support consisting of the other polymer) [ 50 ] were demonstrated in addition to the CDA.…”

“…Among them, the HF configuration had superior advantages to the spiral-wound in the total membrane area, the packing density, and the module performance if the original membrane performance was the same. The spiral-wound type CA membrane was commercialized by many companies and used as the industry standard through the 1960s to mid-1970s [ 37 , 56 ]. However, CA-based membranes were still not widely used for the large-scale desalination purpose at that time [ 57 ].…”

“…With the purpose of achieving seawater desalination in mind, a significant portion of research and development was carried out using a CTA-HF membrane and module by Dow Chemical based on a research contract with the Office of Saline Water in the U.S. Department of the Interior [ 37 ]. Their development results of the RO module for brackish water desalination and for seawater desalination were published in 1970 and 1974, respectively [ 59 , 60 ], and the CTA-based HF RO module for low-pressure brackish water desalination was subsequently marketed in 1974 [ 37 ]. The research developments for the CA-based HF were also conducted by other companies such as Monsanto, Toyobo, and others, in addition to Dow Chemical.…”

“…The research developments for the CA-based HF were also conducted by other companies such as Monsanto, Toyobo, and others, in addition to Dow Chemical. After that, following the early work by Dow Chemical, Toyobo successfully developed a CTA-HF RO module for high-pressure one-pass seawater desalination and subsequently marketed it in 1979 [ 37 , 45 , 61 ]. The CTA-HF RO module was often used in the fishing industry as a small-scale desalination apparatus on a shipping boat [ 62 ].…”