On the adsorption issue of activated carbon
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This post was last edited by zfc318 on 2010-11-11 at 17:27. I used activated carbon for adsorption in water treatment, by passing the wastewater through carbon columns. Theoretically, the organic content in the water coming out should be zero or very low; however, in practice, the organic content in the samples obtained was always between 20-30 ppm. Some of the organic compounds in our wastewater are small molecules – could it be that these small molecules cannot be adsorbed, which is why there is still 20-30 ppm of organic matter in the water coming out? Everyone, please show me what the reason is.
What are the detection indicators for organic matter in wastewater? It’s absolutely impossible for there to be no organic matter.
This post was last edited by Kind Cat on 2010-11-11 at 17:24; it’s possible that the adsorption time was too short, so complete adsorption did not occur. For substances in the same series, the adsorption amount increases as the molecular weight increases; therefore, it is possible that the smaller molecules are not adsorbed
Reply to 3# fangqiong: We conduct TOC analysis to measure the removal of organic substances. After adsorption using activated carbon, the TOC level can be reduced from 80 ppm to 20–30 ppm; we use coconut shell carbon for this purpose.
Reply to 4# Kind Cat: I use 100g of activated carbon in my filter; it can process 500ml of water at a time, and the processing time is 1 hour.
Normally, activated carbon can absorb COD in water down to 0, but that is an ideal situation.
This post was last edited by fangqiong on 2010-11-12 09:56. Activated carbon adsorption seems to be related to molecular weight, after all, adsorption relies on the pores present. In my understanding, if the molecular weight is not appropriate, either adsorption won’t occur or the substance will easily desorb; in any case, achieving a removal level of 0 is quite idealistic.
It is necessary to first pass the water through other filter media before using activated carbon for adsorption, which will yield better results. Achieving a COD level of 0 in the effluent is too idealistic. After all, it is wastewater, so its original COD level must be very high. Generally, treated wastewater can be used as reclaimed water for purposes such as watering plants and washing cars.
It’s impossible to reduce organic matter absorption to zero through adsorption, because adsorption and desorption are balanced processes that occur simultaneously; therefore, it’s not possible to reach a level of zero.
It is highly unlikely that the COD level in the effluent will be 0; small molecules cannot be adsorbed, and this might be related to the micropores of the activated carbon. Please check the iodine value of your activated carbon. We are a manufacturer of activated carbon, and my email address is yelulu780@yahoo.com.cn. Feel free to send me an email if you have any questions
The original poster’s view really needs to be corrected: the adsorption capacity of activated carbon is selective; it cannot effectively adsorb all organic solvent molecules, and it also reaches saturation quite easily. Activated carbon has an excellent adsorption effect on aromatic solvents such as benzene and toluene, but in practice it is not possible to achieve 100% adsorption!