Abstract—Co-adsorption of ammonium, phosphate,
strontium and arsenate ions from polluted water sources by a
low-cost nut residue biochar, without using any chemicals, was
investigated. The adsorption behavior of biochar was examined
for different experimental parameters and the mechanisms of
adsorption were explored through structural, mineralogical
and chemical analyses, as well as modeling of experimental data.
At equilibrium, a higher ionic strength favored the adsorption
process, whereas the uptake of each ion by the solid increased
significantly when all ions co-existed in the solution, implying no
competition between them for sorption sites. The experimental
data were fitted with great accuracy by the Freundlich isotherm
model. The maximum adsorption capacity of the biochar
achieved for ammonium, phosphate, strontium and arsenate
was 50.3 mg/g, 121 mg/g, 66.9 mg/g and 62.9 mg/g, respectively.
The potential mechanisms of adsorption were the chemical
complexation of all ions with the adsorbent, electrostatic
attraction for ammonium and strontium cations, ligand
exchange for phosphate and arsenate ions and mineral surface
precipitation for phosphate, strontium and arsenate ions.
Keywords—co-adsorption, ammonium, phosphate, strontium,
arsenate, biochar
Cite: Despina Vamvuka, George Asiminas, Antonios Stratakis, and Despina Pentari, "Co-adsorption of Ammonium, Phosphate, Strontium and Arsenate from Contaminated Water by a Low Cost Biochar. Performance and Mechanisms," International Journal of Environmental Science and Development vol. 16, no. 3, pp. 164-173, 2025.
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