Abstract:
In the current study activated carbon supported zero-valent iron nanoparticles were synthesised,
characterized and used for phosphate adsorption study. Batch adsorption experiments were carried out to
study the effect of activated carbon supported nZVI nanocomposites on the removal of phosphorus (P) from
50 mg/L P contaminated water at various pH values. When the activated carbon supported nZVI dosage
increased from 2 g/L to 8 g/L the percentage P adsorbed increased from 69 % to 99.5%. The amount of P
adsorbed increased with an increasing concentration of activated carbon supported nZVI dosage and
decreasing pH values. Increasing adsorption of P with increasing adsorbent dosage can be due to higher
adsorption site, however at higher adsorption dosages beyond 8 g/L the adsorption showed a decreasing
trend due to the saturation and overlapping of adsorption sites. When the pH value of the solution increased
from 3 to 11 the percentage removal of P decreased from 99.5 to 12 %. The reduction in adsorption at
increasing pH values can be attributed to the repulsion between hydroxylic ions (OH¯
) on the surface of iron
nanoparticles and the existence of P in the form of phosphate anions (H2PO4¯, HPO4¯and PO4
3¯ ). Langmuir
and Freundlich adsorption models were fitted in the experimental data, and it was found that the Langmuir
model fitted well, and the calculated maximum adsorption capacity of phosphate was 68 mg/g, suggesting
significantly higher and remarkable uptake of phosphate by activated carbon supported nZVI particles. The
findings of this study showed that silica coated ZVI Particles could be promising adsorbents for removal of
phosphates from polluted water bodies effectively.
