Hi,
I built a stirring-type calcium hydroxide reactor (it sits on a stir plate with a rare earth magnet stir bar) that is 40" tall out of 4" diameter PVC with an integral pH probe. I typically add one cup of fresh calcium hydroxide (from BRS, purchased approximately 2 months ago) to the reactor to charge it. The reactor stirs constantly at 300 rpm with a standing 20" column of swirling milky undissolved calcium hydroxide and 20" of clear kalkwasser above that. Fresh water is introduced to the bottom of the reactor and CaOH-saturated kalkwasser is pushed out the top at 1 ml/min when the reactor is on. The reactor runs for approximately 14 hours per day, adding approximately 840 cc of CaOH-saturated water to the tank.
My dilemma is this. When I first fill the reactor with fresh CaOH and RODI water, the pH is 12.3. Given pH probe errors, I assume this is saturated. However, the pH of the effluent begins to drop linearly as soon as it comes online and by 10 days after filling is down to 9.5. Bear in mind, that there is still a 20" high vortex of milky CaOH swirling continuously at 300 rpm at the bottom of the reactor at this point. I feel like 1 cup of CaOH should last a bit longer than 10 days but would appreciate your insight into this matter.
Thanks,
Mike
I built a stirring-type calcium hydroxide reactor (it sits on a stir plate with a rare earth magnet stir bar) that is 40" tall out of 4" diameter PVC with an integral pH probe. I typically add one cup of fresh calcium hydroxide (from BRS, purchased approximately 2 months ago) to the reactor to charge it. The reactor stirs constantly at 300 rpm with a standing 20" column of swirling milky undissolved calcium hydroxide and 20" of clear kalkwasser above that. Fresh water is introduced to the bottom of the reactor and CaOH-saturated kalkwasser is pushed out the top at 1 ml/min when the reactor is on. The reactor runs for approximately 14 hours per day, adding approximately 840 cc of CaOH-saturated water to the tank.
My dilemma is this. When I first fill the reactor with fresh CaOH and RODI water, the pH is 12.3. Given pH probe errors, I assume this is saturated. However, the pH of the effluent begins to drop linearly as soon as it comes online and by 10 days after filling is down to 9.5. Bear in mind, that there is still a 20" high vortex of milky CaOH swirling continuously at 300 rpm at the bottom of the reactor at this point. I feel like 1 cup of CaOH should last a bit longer than 10 days but would appreciate your insight into this matter.
Thanks,
Mike