I'm performing CDI experiments wherein to find deionization rate i need to know the ionic concentration of influent and effluent. Can anybody please explain how to find?
A simple and inexpensive way to continuously monitor ionic concentration is to use electrical conductivity (EC) meters. Electrical conductance is tightly associated with ionic concentration, particularly if the identity of the major ions does not change significantly over time. Just put one EC meter probe in the influent stream and one EC meter probe in the effluent stream. EC readings will fluctate with fluctuations in ionic concentration of the influent and/or effluent streams. If the identity of the major ions is known, then electrical conductance readings can be converted to total ion concentration with high accuracy.
Specific conductance is one of the most continuously measured water quality parameters. Measures the capacity of water to carry electrical current. Its value depends on the ionic concentration in the water which is carried by the current.
The greater the ionic concentration in the water, the greater the specific conductance. The most common conductive ions found in water are calcium, magnesium, sodium, chloride and sulfate, among others.
There is a relationship between the specific conductance measured continuously and the ionic concentration of sodium, calcium, chloride and sulfate, in general of the total dissolved solids, using parametric and non-parametric regression models.
This relationship will give you the ionic concentration in the influent and effluent of your plant at any time.
There are non-expensive portable meters that provide readings in Conductivity in microSiemens/cm and in TDS in ppm, which are very economical.
Singh, T. and Kalra, Y.P., 1975. Specific conductance method for in situ estimation of total dissolved solids. J. Am. Water Works Assoc., v. 67, no. 2. p. 99.
If there are any heavy metallic ions not present then you can try with Ion chromatography (IC) which could be beneficial.
Additionally, for heavy metallic ions AAS & ICP technique could be a promissing ones.
Md. Mahmudur Rahman Sir, feed water does not contain any heavy metal ions.
example, I will send feed water say 1M NaCl to the CDI device and run the process then i will collect another side the pure water and check the conductivity [ if init conductivity was 58.97 mS/cm then final pure water has slight changes say around 55.07 mS/cm] so to find the deionization rate i need a concentration of influent and effluent.
By using Ion Chromatography (IC) you can easily tedect & quanyify the amount of Na ion in water body.
As James C. Trask already explained: If the identity of the major ions is known, then electrical conductance readings can be converted to total ion concentrations with high accuracy. Using the concentrations of the major ions you can deduct your very own specific conversion formula, just check from time to time if the concentrations are still valid.
yes sir i tried keeping the conductivity probe in the influent and effluent i found variations in the conductivity, the effluent was 58.70 mS/cm but the influent was 60.88 mS/cm. so should I need to consider these values as ionic concentrations of influent and effluent directly?
The difference in electrical conductivity is only 3.6%; I would consider the results to be nearly equivalent. However, there is no guarantee that the ionic composition will also remain the same. If this is important, verification and occasional confirmation through chemical analyses must be conducted.
More can certainly be elaborated on this topic (refer to relevant textbooks for further details), but this is actually unnecessary sice your question is unfortunately completely without context, as the actual problem is not known.
Always willing to help or discuss!
PF
Mahima--one way to help determine whether or not the difference in conductivities of influent and effluent are real (and not due to small errors in readings) is to do the following, using a single conductivity probe used for your measurements: collect a sample from the influent in one sample container and a sample from the effluent in another sample container. Using your dry and clean conductivity probe, measure the conductivity of one of these samples, dry off your probe, and then immediately measure the conductivity of your other sample with the same probe. Do this several times, with several sets of samples. If the effluent conductivity readings are consistently lower than the influent conductivity readings, then it is likely that these results reflect real differences in conductivity (and of ionic concentrations) between the influent and effluent, and is not just an artifact of small errors in probe readings.
James C. Trask yes sir I did similar passion as you said, but lacking to calculate salt adsorption capacity
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