(299b) Nanofiltration: High Potential, Poorly Defined and Understood

Nanofiltration: High Potential, Poorly Defined and Understood

The membrane mediated process known as nanofiltration is receiving much attention, but some of it due to the erroneous assumption that the technology came out of recent nano-materials advances, or that it performs based on the characteristics of nanoparticles. In reality, nanofiltration (NF) has been employed commercially for four decades, predating today’s popular concept of nanotechnology. Even within the maturing membrane industry, nanofiltration is defined in varying manners. For an important technology to advance to full potential, such definitional incoherence is counterproductive.

The potential of nanofiltration is very high, and could be applied in more unique ways than its sibling membranes processes.  To aid the research and industrial communities’ understanding, this paper defines the current reality of the nanofiltration process, and addresses its history and its probable future. Few realize when the first NF membranes were developed, and for which applications and the origin of the term nanofiltration. Interestingly, the earliest NF membranes were involved in a patent suit that led to a seminal US Supreme Court decision, the only involving patent interpretation in a three decades span. These and other historical highlights are presented to help put the importance of this process in perspective.

The NF process is briefly described in relationship to the better understood membrane classes, reverse osmosis and ultrafiltration (RO and UF). Further definition is provided by description and comparison of NF’s major applications in water treatment, industrial manufacturing and the more exotic emerging uses for medicines, fine chemicals and biofuels.

The lack of communication and common among the industries that use NF explains its incoherent definition. Lack of standardization and poor cooperation among standards setting organizations are described. Specific examples of misunderstandings that serve as roadblocks to the use of this process are given, including differences in definitions by standards groups, a membrane vendors and user groups (industries) are presented. Different views between the municipal water treatment community, industrial engineers, and the research community are described. A more universal definition, of both the process and its mediating membrane is proposed.

Whether defined as “nanotechnology” or not, separation of materials at the molecular level is a key to emerging technologies in several arenas of use. The paper concludes with a summary of recent advances, failed efforts, technical avenues to improve the membranes and the author’s predictions for near and long-term improvements.