Hydrothermal decoration of iron oxide nanoparticles on expanded graphite for adsorptional of phosphorus

This study is to investigate the feasibility of iron oxide nanoparticles coated expanded graphite (EG) as adsorbents by hydrothermal decoration method for phosphorus removal from aqueous solution. Batch adsorption experiments were performed at various temperatures to investigate thermodynamic of the process using hematite coated EG (Hematite/EG) and FeOOH coated EG (FeOOH/EG). The impact of natural organic matter (NOM), ionic strength, and pH during the adsorption was also evaluated. The results show that the equilibrium data were well fitted with Langmuir isotherm model, and the calculated maximum adsorption capacities were 4.07 mg-P/g and 0.43 mg-P/g for FeOOH/EG and Hematite/EG, respectively. In both adsorption processes, thermodynamic parameters explained that the adsorption of phosphate onto the materials was endothermic in nature, feasible and spontaneous, and increased as the increasing of temperature. pH was investigated as the critical parameter on the adsorption of phosphorus, while the impacts of natural organic matter and ionic strength were negligible. Our study suggested that the hydrothermal decoration of iron oxide nanoparticles on EG could be used as the adsorbent for the removal of phosphorus from wastewater.