Investigations on phosphorus recovery characteristics by active carbon prepared from date stones in aqueous solutions

The efficiency of raw date stones (RDS), its derived activated carbon (DS-AC) and a commercial active carbon (AC) in recovering phosphorus (P) from aqueous solutions was investigated in batch mode under different experimental conditions. The chemical activation process using sulfuric acid (H2SO4) revealed that compared to RDS, the DS-AC has improved physico-chemical characteristic including a high specific surface (612 m2/g) and an important micro-pore volume (0.27 cm3/g). This has resulted in the increase of P adsorption capacity by about 50.5%, reaching a value of 25.2 mg/g. Moreover, the P recovery by DS-AC seems to be relatively rapid and significantly affected by the pH of the aqueous media and the presence of other ions, especially calcium. This adsorption process might be mainly chemical involving cation exchange process. Adsorption isotherms have been applied to study the P adsorption behavior and to determine the adsorption capacity of the absorbents. Regression analysis was used to study the empirical statistics of the experiments and to identify the significance of the parameters used to enhance the P adsorption capacity. This study proves that DS-AC can be considered as a promising and economic material for P ions recovery from aqueous solutions for a further subsequent use in other domains such as agriculture.