Efficient adsorption of fluoride ions by polyethyleneimine modified diatomite under different conditions in a fixed bed column

ABSTRACT This study investigated the removal efficiency of fluoride ions (F – ) using polyethyleneimine modified diatomite earth (PEI&DT) in a fixed bed column under different conditions. Scanning electron microscopy showed that the PEI&DT had high porosity and thermogravimetric analysis showed that the diatomite was successfully modified by polyethyleneimine (PEI). Adsorption of F – by PEI&DT was measured in the fixed bed column using breakthrough time and saturation time, which increased with increasing bed height, but decreased with increasing F – concentration and flow rate. The Thomas model, which had a very good fit (average = R 2 > 0.9632), showed that the maximum q 0 value was 97.06 mg/g. The Yoon–Nelson model predicted theoretical required times (τ theo ) were close to the experimental values (τ exp ), and the mean error (β) < 9% showed the model was accurate. These results demonstrated that PEI&DT has high potential as an adsorbent for the removal of F – in a fixed bed column.