Work

Phosphorus removal from aqueous solutions using hematite-coated expanded graphite: Isotherm modeling and thermodynamic insights

Year: 2025

Type: article

Abstract: Hematite-coated expanded graphite, a newly developed nanocomposite, has demonstrated high efficiency as an adsorbent for the removal of various metal ions and inorganic contaminants from aqueous solutions. To enhance its durability and adsorption performance, hematite nanoparticles were synthesized onto expanded graphite, and the adsorption behavior for inorganic pollutants was investigated at different temperatures. The adsorption isotherms were best fitted by the Langmuir model, indicating monolayer adsorption on a homogeneous surface. The maximum adsorption capacity for phosphorus was determined to be 33.3 mg/g at 298 K. A slight decrease in adsorption capacity was observed with increasing temperature, suggesting that the process is exothermic in nature. Thermodynamic analysis revealed a Gibbs free energy change (ΔG) ranging from –22.4 to –22.6 kJ/mol, an enthalpy change (ΔH) of –89.5 kJ/mol, and an entropy change (ΔS) of –0.2 kJ/mol·K, further confirming the spontaneous and exothermic characteristics of the adsorption process. Combined results from isotherm and kinetic studies indicate that α-Fe2O3/EG is a promising adsorbent for the efficient removal of trace amounts of phosphorus from water.

Source: Environmental Engineering Research

DOI: 10.4491/eer.2025.359

Authors: Myungchan Kim, Kanghoon Lee, Duksoo Jang, Sungju Im

Language: English

Topic: Phosphorus and nutrient management

Subfield: Waste Management and Disposal

Field: Environmental Science

Domain: Physical Sciences

SDGs: Clean water and sanitation, Responsible consumption and production

Open Access status: diamond

Funders: Ministry of Environment, National Research Foundation of Korea, Ministry of Science and ICT, South Korea

Awards: G317236198, G5402896961