aschaefer023

I have seen different equations for SO2 reacting with NaOH but this site: http://www.monroeenvironmental.com/air-and-gas-cleaning-systems/packed-bed-fume-scrubbers/packed-bed-scrubbers-applications-and-engineering suggests one mole of NaOH reacts with one mole of SO2 to form NaHSO3 and Na2SO3 (in the presence of excess NaOH) I know the constant of 379 SCF per lbmol of gas. So 15cf X 1lbmol/379cf = 0.0396 lbmol gas total (or 17.952 mol) the molar mass of air is 28.97 g/mol and the molar mass of SO2 is 64.07 g/mol so in 1 million grams of gas we have (300,000g SO2 X 1 mol SO2/64.07g) + (700,000 g air X 1 mol air/28.97 g) = 28,845.31 mols (please dont comment on my sig figs I'm just quickly crunching numbers) so 1,000,000 grams / 28,845.31 mols = 34.67 g/mol for the inlet gas 34.67 g/mol X 17.952 mols/15cf = 622.35 grams gas per 15 cf 622.35 g gas X 0.3 g SO2/g gas = 186.71 g SO2 per 15 cf 186.71 g SO2 X 1 mol/64.07 g SO2 = 2.91 mol SO2 per 15 cf of inlet gas if we need one mol NaOH per one mol SO2 (please correct me if you believe this is wrong) then we also need 2.91 mol NaOH per 15 cf of inlet gas to react according to chembuddy.com a solution of 20% NaOH has a density of 1.2219 g/mL so in 1 mL we have 1.2219 g solution X 0.2 g NaOH/g solution = 0.2444 g NaOH per mL molar mass of NaOH is 39.997 g/mol need 2.91 mol NaOH 2.91 mol NaOH X 39.997 g/mol X 1mL/0.2444 g NaOH = 476.27 mL of 20% NaOH solution for every 15 cf converting back to american units and changing so the answer is in hours and not minutes: 476.27 mL/minute X 60 minutes/hr X 1 gallon/3785.41mL = 7.55 gallons of 20% NaOH solution per hour Does this seem right? For the second part of the question I guess you are saying there isn't enough information because we do not know the initial volume of the inlet gas to be neutralized. But I could calculate how much time per cf of initial gas like: 15 ft3/min X 60 min/hr = 900 ft3/hr or that it will be 0.0011 hours per cf of the initial 300,000 ppm SO2 please comment back to let me know what you think of my calculations. Am I going about this correctly? Or am I way off? Thanks

I would just like to know what equations I would need to answer a question like this. I am sure once I have the equation the math will be very simple. Any help or advice would be greatly appreciated. "When using a recirculating packed column scrubber that is 100% efficient how much sodium hydroxide at 20% would be used per hour if the flow rate of 300,000 ppm SO2 was 15 cfm? How many hours could we run the scrubber until the caustic had neutralized all of the SO2?" I assume 100% efficient means the outlet gas stream has a SO2 concentration of 0% but I could be wrong. Can anyone give me any help setting up the equations for these two problems?