Phosphate adsorption characteristics of wasted low-grade iron ore with phosphorus used as natural adsorbent for aqueous solution

A low-grade iron ore with phosphorus (LGIOWP), the extensive industrial solid waste generated in mining of high phosphorus iron ore, was investigated to assess the effectiveness for the removal of phosphate from aqueous solution. The factors influencing the adsorption were examined, and the related adsorption mechanism was discussed. The results showed that pH value had a significant effect on the phosphate removal. The optimum pH value for phosphate adsorption was 5.6. The adsorption of phosphate mainly on hematite ligand exchange is likely the key mechanism for phosphate removal when pH is in the range of 1−9. When pH value was above 9, the presence of dolomite played an important role in phosphate removal. The adsorption capacity is enhanced with a higher initial phosphate concentration. Kinetic studies show that the adsorption follow pseudo-second-order kinetic model. Langmuir and Freundlich isotherms were used to simulate the adsorption equilibrium data. The adsorption fits well with the Langmuir isotherm model and the maximum adsorption capacity is found to be 11.44 mg/g. Due to possessing the low cost and high capability, LGIOWP could be a promising material for phosphate removal in the wastewater treatment.