One of themost important factors affecting the capacity of adsorbent
in wastewater treatment is solution pH. The efficiency of adsorption
is dependent on the solution pH, since variation in pH leads to the functional group such as OH− group, cationic dye adsorption is
favoured at pH N pHpzc, whereas, anionic dye adsorption is favoured at
pH b pHpzc where the surface becomes positively charged