In the Column treatment of aqueous solution of Chromium Removal by Adsorption
Ali Safaa Can you give a reference to a study that used the procedure you mention.
Treating bark with acid (HCl) first and then with base (NaOH) second is a common method for isolating plant compounds for analysis or extraction, such as tannins, lignin, and cellulose. This method is known as acid-base treatment or A/B extraction.
The reason for this order of treatment is that acid treatment hydrolyzes and breaks down the plant cell walls, making the cell contents more accessible for extraction. Acid treatment can also help to remove impurities, such as pigments and waxes, from the sample.
After acid treatment, the sample is then neutralized with a base, typically sodium hydroxide (NaOH), to restore the pH to a neutral or slightly alkaline state. The neutralization step is important to prevent the acid from interfering with subsequent analytical techniques or reactions.
The use of acid and base treatments in this order allows for selective extraction of different plant compounds based on their solubility and chemical properties. For example, tannins are more soluble in acidic solutions, while lignin and cellulose are more soluble in basic solutions.
Treating the bark with base first would result in a saponification reaction, where the ester linkages in the plant compounds would be hydrolyzed by the base, resulting in a loss of their original structure and properties. Therefore, treating the bark with acid first and then with base is the preferred order for A/B extraction of plant compounds from bark.
The use of acid and base treatments in this order allows for the selective extraction of different plant compounds based on their solubility and chemical properties and purification.
Henrik Rasmus Andersen Rajat Kumar yes, Thank you very much, Currently I don‘t have Reference, but a i did a quick search i find a related one that says
(The electrostatic interactions of metal ion cations are increased by sodium hydroxide (NaOH), while at the same time providing optimal conditions for ion exchange, while hydrogen-chloride (HCl) dissolves the polysaccharides of the cell wall and also replaces light metal ions with a proton, thereby increasing the biosorption binding sites)
https://encyclopedia.pub/entry/16300
Some Researchers use only Acids, others only Base, and some use both, they said that it increases the pores of the bark or any waste (Residue) for better Adsorption, like Activation, also NaOH is detergent like decolorizing agent for cleaning from mud, dirt etc…
And then by comparing Raw and Treated waste, it is supposed that treated one must give better results of Chromium Removal
the image below is from proposal thesis of my supervisor
If the intend is to use the treated bark as a chromate absorber it might make sense to have the base treatment last in order to leave the anion exchange sites charged with hydroxide that can be exchanged with chromate (also an anion). I suspect bark isn't a very efficient sorbent for chromate so it might also contribute to the removal by reducing chromate to chrome(III). If the reduction mechanish is important it would likely be better to have the acid last and as low as possible pH during the treatment.
The reason for this order of treatment is that acid treatment hydrolyzes and breaks down the plant cell walls, making the cell contents more accessible for extraction.
Theia'a Al-Sabha Why do you want the cell content more accessible for extraction in a chrom sorption column?
Treating bark with acid (HCl) first and then with a base (NaOH) is a common process known as acid-base extraction or acid-base treatment. This method is used to extract specific compounds from the bark or plant material.
The reason for using acid first and then base is based on the chemical properties of the compounds present in the bark. Different compounds have different solubilities in acidic and basic solutions, and the acid-base treatment takes advantage of these properties to selectively extract desired compounds.
Here's a general explanation of the process:
By sequentially treating the bark with acid and base, different classes of compounds can be selectively extracted into separate solutions. This process allows researchers or chemists to target specific compounds of interest, isolating them for further analysis or use.
It's worth noting that the specific choice of acids, bases, and the order of treatment may vary depending on the target compounds and the desired outcome of the extraction process. Different plants or barks may require variations in the extraction method to achieve optimal results.
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