i want to run some adsorption test using biochar but i want to check the pH first
must i necessarily follow the IBI Biochar international guideline ? or i can determine using another method?
can anyone help ?
Your reason for determining pH is different that the reason for the standard guidelines. Your reason is to examine the adsorption of either organic compounds or metal species under conditions that likely would be applicable in the field (in application). This means that the pH (and buffer capacity) of the water you are treating will affect the final pH. If you perform batch adsorption tests, the pH may even be different than if you create a biochar column to treat the water in a flow-through system, as the pH in the latter case may change over time (over pore volume). Hence, you should determine pH the best way that is applicable for your "biochar application" questions. I would suggest that at the minimum, you should measure not only pH, but the buffer capacity of the biochar and of the water that you wish to treat, and the necessary precision of these measurements depends on whether you wish to adsorb ionic, ionizable organics, or metal species that may complex with hydroxide or other ligands that may exist in the water. At a minimum and to have reproducible results, you may consider controlling pH at several values in a series of experiments to see if pH is an important variable. Hope this helps.
Dear Samiratu Isa ,
Chad T Jafvert has already provided very important points highlighting that the reason for pH measurement is different.
Should you wish to avoid the interference of material leaching out from the biochar during your adsorption experiment I recommend to wash the biochar first. This is quite common for lab-based sorption studies (see Table 1 in Article Adsorption of NPK fertilizer and humic acid on palm kernel s...
).Washing can be done with deionised water or mild acidic solutions. If you use mild acidic solutions you need to wash off the residual acid before commencing with the sorption experiment. I recommend to use conductivity as indicator to know whether washing has removed the leachable minerals. Once conductivity is similar to distilled water you can stop washing. In order to know the pH of the washed biochar I recommend to determine the pH of point of zero charge (pHpzc) (Article Influence of Pyrolysis Temperature on Biochar Property and F...
).All the best, Rob.
Dear Samiratu Isa
You can use the following method that I had read in a paper before. I think it will solve your problem.
Recommended procedure for biochar pH measurement
Materials
● pH meter with glass–calomel electrodes.
● Deionised water.
● 100 mL centrifuge tubes or bottles.
● Automatic dispenser to deliver 50 mL.
● Standard buffers (pH 4, 7 and 10).
● Reciprocating shaker.
Procedure
(1) Weigh 5.0 g air-dried biochar sample (ground to
thank you very much
these answers got me deep thinking than before i wil certainly try out and see
thank you
Please refer to the following paper:
Effect of thiourea-modified biochar on adsorption and fractionation of cadmium and lead in contaminated acidic soil. International Journal of Phytoremediation.
DOI: 10.1080/15226514.2019.1678108
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