Dear All,
In order to determine the H2S adsorption capacity of zeolite, we prepared a set-up by using a Kips Apparatus. We generated H2S as follows:
FeS + 2 HCl ----> FeCl2 + H2S and sent it to the CuSO4 solution after passing through the zeolite.
CuSO4•5H2O + H2S ----> CuS↓ + H2SO4 + 5H2O.
CuS is precipitated when H2S goes through the system and Cu amount is reduced in time.
We did the measurements several times both in the absence and presence of zeolite. We performed ICP-MS measurements to determine the Cu amount. The strange thing is that the Cu amount increased in the absence of zeolite and decreased when zeolite was used. Isn't it strange? Did we do something wrong?
Which method would you recommend us to determine the H2S amount by using this set-up? Would it be possible to determine H2S adsorption capacity by titration methods? Please try to give the method as detailed as possible!
I really appreciate your kind help in advance.
Ilhan
Dear;
hydrogen sulfide absorbed on crystalline zeolites can be determined by forced desorption of H2S using a hot stream of oxidizing oxygen flowing through the zeolite bed at a temperature higher than 230 C, followed by another bed with vanadium pentoxide to convert SO2 to SO3 this stage is followed by a SO3 absorption apparatus to determine SO3,.
Hello Ilhan,
May be I did not understand the reactions properly or my thought process is skewed, but the way you explained I think your results make sense to me!
In the absence of zeolite no H2S is adsorbed and therefore more H2S reacts with CuSO4 to produce more CuS. That is what you measured! With zeolite, less H2S will precipitate less amount of CuS.
Dear Krishnan,
I measured the Cu amount in the solution not the precipitate!
Thank you
Ilhan
As a matter of fact, a physical approach to determine adsorption is more accurate than (indirect) chemical methods to determine adsorption.
H2S can be measured very sensitively. Analysis of H2S concentrations using GC with sulfur chemiluminescence detection relies on the measurement of H2S in an open flow system sample chamber. H2S present in the gas phase is measured following GC separation from other sulfur compounds and detected using a 355 sulfur chemiluminescence detector (Agilent Technologies, Santa Clara, CA). In the detector, the sample undergoes combustion in a furnace generating sulfur monoxide, which reacts with ozone in a reaction cell to form sulfur dioxide, emitting light (by chemiluminescence). The light intensity is measured using a photomultiplier tube and the signal is linearly proportional to the quantity of sulfur in the sample.
The GC method allows separation of H2S from different natural sulfur compounds (Levitt, Furne, Springfield, Suarez, & DeMaster, 1999). The sensitivity of the instrument allows detection of mixing ratio's as low as 0.5 pg of sulfur and the linear range spans approximately four orders of magnitude based on the vendor’s information.
An open flow system is required with the possibility to input of different concentrations of H2S in a mixing (ratio) recipient. The difference between input and output of the open flow system recipeient gives you the adsorbed amount of H2S in function of time. When these kinetics are integrated (numerically) you obtain the total amount of H2S adsorbed by your zeolite. Accuracy is lower than 5% SD. A zeolite heating device can be included in the recipient, to measure adsorption (and desorption) at different temperatures.
CHeers and have fun.
the only problem with Jamal's solution is the limit of detection. Frank is right GC with special detector can work better.
another point, temperature of SO2 to SO3 over V2O5 should be higher than 450 C
Hi. I would also recommend GC for such experiments.
Please check: https://www.researchgate.net/publication/333778167_Adsorption_and_gas_sensing_properties_of_CuFe2O4_nanoparticles
