Process and apparatus for separating sulfate ions from waters and for introducing buffer capacity into waters

摘要

Both cathode chambers are arranged on either side of central anode chambers. An ion exchange membrane intervenes between anode- and cathode chambers. Anions are transported in solution from the cathode chambers through the membranes and into the anode chambers, hence separating them. In the cathode chambers, oxygen or air and/or carbon dioxide are introduced into the fluid in finely-divided form. The oxygen is converted electrochemically at the cathode surfaces to hydroxide ions. The carbon dioxide reacts with calcium or magnesium cations in the fluid, to form corresponding bicarbonates, so raising the buffer capacity in solution. The anode comprises a substrate material coated with less than 20% of electrochemically-active material comprising: graphite, carbon-glass, synthetic doped diamond, chemical elements with atomic number 44-46 and 75-79, their compounds, alloys or oxide compounds. Anode current density exceeds cathode current density by a factor of five or more. The anode current density is greater in the lower part of the cell than in the upper. Spacing between cathode and ion exchange membrane is 0.5 - 7 mm. The interspace so formed between them, contains an electrically-insulating material. Various further anions and cations (listed) may be contained in solution. The process is further detailed. An independent claim is included for corresponding apparatus.