I was intrigued to read the article about Akira Fujishima and the marvelous properties of titanium dioxide (C&EN, June 8, page 30). In 1960, the Department of the Interior’s Office of Saline Water (OSW) wanted to make plastic covers for solar stills that were wettable in order to prevent the condensate from forming drops, which lowered efficiency by reflecting sunlight and by falling back into the saline basin.
My solution, in an OSW-sponsored project at the Franklin Institute Laboratories for Research & Development, was to coat the polyvinyl fluoride covers with TiO2 formed by hydrolysis of tetraisopropyl titanate deposited from solution. In an outdoor test, I was pleased to see filmwise condensation continuing after many months’ exposure to the sun.
If interest is renewed in large-scale solar distillation of seawater, TiO2-coated plastic covers may perform a useful role.
Robert A. Erb
Valley Forge, Pa.