pH is a critical parameter that significantly influences the adsorption process. Adjusting the pH using 0.1M NaOH or HCl helps optimize the conditions for better adsorption, as it affects the surface charge of the adsorbent and the ionization state of the adsorbate.

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0.1 molar solutions of HCl and NaOH are readily available in the lab and when used for pH adjustment have a very low tendency to form buffers or complexes that could interfere with the test work.