For a biosorbent, effect of pH variation from (3 ~ 10) on % removal efficiency of Nitrates from water is recorded. Max. removal is at pH 7. Does this wavy graph make sense?
Graph seems strange. However, it could well be because of the adsorbent used and presence of other competing cations. What active surfaces are available on the bio-adsorbent surface and how they react at different pH. Bear in mind that a particular adsorbent surface could have a myriad of active sites with different properties. What about the effect of pH on the biosorbent? Will it change the properties of the active sites? Has a pHzpc been determined?
Highest adsorption seen at pH7. Then it declines rapidly at pH6 and improves at pH4.7 before declining again. This could become a potential method for reusing the adsorbent by regenerating it by adjusting the pH. Worth further study.