The first hollow-fibre RO membrane, USA

Founded in 1802 as a gunpowder manufacturer, DuPont eventually became the world’s second largest chemical company with the development of materials that included nylon, neoprene and Teflon. In the early 1960s, soon after Loeb and Sourirajan’s membrane work at UCLA was published, DuPont began to conduct membrane research as a way to expand its textile fibre business.

The DuPont B10 SWRO permeator. – Tom Pankratz

by Tom Pankratz

Its developmental B1–4 membrane was based on 6-nylon fibres and, although it provided successful separation, it had a very short lifespan. The next generation – the B5 – was the first membrane to use an aromatic polyamide and led to the commercialisation of the B9 brackish water membrane in 1969, followed by the introduction of the B10 ‘permeator’ for seawater applications in 1976.

Although the fibres continued to be spun in Waynesboro, Virginia, and assembled into elements in Glasgow, Delaware, the RO membrane was pulled from DuPont’s Organic Chemical Group in 1977 and rebranded within the Permasep Polymer Products Group run by Bob Keller. By winning five of six Riyadh, Saudi Arabia, water plant projects, the company was successful enough to keep going.

The membrane group was restructured in 1978 with Irving Moch as the technical manager, and it captured a 70% share of the seawater market until the mid-1980s.

By the late 1990s, DuPont had put the Permasep Products business up for sale, but was unable to come to terms with several potential buyers. Apparently, the membrane material was a ‘first cousin’ of Kevlar and Nomex – highly successful proprietary DuPont products – and DuPont was not willing to fully disclose the chemistry of the membranes, and the prospective buyers would not have full control of the raw materials.

DuPont closed its Permasep group in 1999, and by 2004 it had shut down the Waynesboro and Glasgow manufacturing sites, sold its residual inventory, archived its intellectual property and adjudicated all warranties, permanently leaving the membrane business.