Asbestos free technology

Chloralp Asbestos-Fr e Technology. Chloralp, a joint venture of Rhone-Poulenc and La Roche, has developed an asbestos-free diaphragm based on the built-in activation concept. The Chloralp separator is made of two vacuum-deposited layers ... 

The largest of these processes remains those for ammonium and sodium persulphate and there are several plants operating on the 2000—10000 ton yr scale. The process involves the oxidation of the sulphate in a sulphuric acid medium at a Pt-based anode and the medium must be free of heavy-metal ions which catalyse the decomposition of persulphate. The current density is high, about 1 A cm" and the current efficiency 60—80%. Two cell technologies are used one uses a cell with an asbestos diaphragm while the other is an undivided concentric tube cell. To avoid reduction of the persulphate at the cathode, the conversion per pass is kept low and the persulphate is crystallized between passes through the cell. 

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