Activated Biocarbons for the Removal of Dibutyl Phthalate from Water: Influence of Salinity, Temperature and Working Cycles

The global deterioration of water quality caused by industrial, agricultural, and domestic pollutants poses significant threats to aquatic ecosystems and human health. The significance of this study lies in addressing a critical gap in the remediation of emerging contaminants by evaluating biochar-based adsorption under environmentally relevant hydrochemical conditions. Four activated biocarbons—A-ac-NiO-ext-1:1, A-ac-Fe3O4-NiO-ext-1:1, A-ac-Fe3O4-1:2, and A-ac-Alg—synthesized from apple pomace were investigated. Their adsorption performance was evaluated under four salinity conditions (M0–M3; total dissolved solids: 0–6123 mg/L), at temperatures of 298, 318, and 338 K, and over three consecutive adsorption–desorption cycles. DBP concentrations were determined by GC–MS. The maximum adsorption capacity, 6.25 mg DBP/g, was achieved by A-ac-Fe3O4-1:2 at 338 K under M3. Salinity effects were material-dependent: A-ac-NiO-ext-1:1 exhibited decreased adsorption with increasing ionic strength, whereas A-ac-Fe3O4-1:2 showed enhanced adsorption, potentially due to salting-out effects. A-ac-Fe3O4-NiO-ext-1:1 maintained stable performance across salinity conditions, while A-ac-Alg exhibited a nonlinear response. The main novelty of this study was the systematic comparative evaluation of four differently functionalized apple pomace-derived activated biochars, integrating the effects of salinity, temperature, thermodynamics, and cyclic reusability within a unified experimental framework.