pH increases, the degree
of dissociation of 2,4-D molecules becomes higher thereby making
it more negatively charged. This leads to increased electrostatic
repulsion or dispersion between the 2,4-D ions and the CCAC surface
and subsequently a decrease in 2,4-D uptake with increase in
pH as was observed in the pH range studied (Fig. 7). The surface
charge of CCAC is neutral at pH of 3.5 (pHPZC of CCAC). The CCAC
surface is positively charged at pH below 3.5 and negatively charged
at pH above 3.5. Hence, CCAC exhibits higher adsorption potential
for 2,4-D at lower pH. FTIR analysis showed minimal involvement