Kinetic and equilibrium studies of phosphorous adsorption: Effect of physical and chemical properties of adsorption agent

• Several materials, with and without thermal treatment, were used as phosphorus removal agents.
• P adsorption depends on the materials composition and porosity.
• Adsorption nature was chemical for zeolites and physical for the remaining material.
• Langmuir and Freundlich models both described the phosphorus adsorption on materials.
• ES reduce in 80% the wastewater phosphorus concentration after 3 h of contact.

Several materials, with and without thermal treatment, were used as phosphorus removal agents. Surface area, porosity and chemical composition were determined for each material aiming to study their effect on phosphorus removal. While, calcined waste eggshell (ES) and natural crushed minerals (calcium (M1), iron (M2) and aluminum (M3)) were not sensible to pH variation, zeolites, USY and HY, exhibited a maximum removal above pH 4. Laboratory adsorption experiments (72 h of equilibrium at 22 °C and 200 rpm) using the different materials revealed a phosphorous removal ability of 26.48, 0.14, 0.14, 0.11, 0.12 and 0.10 mgP g−1 for ES, USY, HY, M1, M2 and M3, respectively. The adsorption revealed to be chemical for USY and HY and physical for the remaining materials. ES demonstrated to efficiently reduce the phosphorus concentration present in wastewater.