Olive branches activated carbon: synthesis, phenol adsorption and modeling

The present study investigated both the feasibility of activated carbon (AC) production from olive tree branches and its application as an adsorbent for aqueous phase phenol removal. The response surface methodology (RSM) based modeling approach was also employed for both activated carbon production and phenol adsorption process optimization. Several olive branches activated carbon (OBAC) samples were synthesized under a varying set of chemical activation conditions. The OBAC synthesized at carbonation temperature of 700 °C, impregnation ratio (I-R) of 2.0 mL/g and acid strength of 60% yielded maximum BET specific surface area (SSA) of 1420 m²/g along with an average pore diameter of 43.46 Å. The study also revealed that the produced activated carbon has a high thermal stability and possesses several active surface functional groups. Furthermore, the application of olive branches activated carbon (with the highest SSA) showed good phenol removal efficiency from synthetic wastewater under a varying set of operating conditions for pH, initial phenol concentration and adsorbent dosage. The kinetic study showed that the adsorption process follows pseudo-First-order kinetics (R² = 0.9872) with a rate constant of 0.127 min⁻¹. The developed RSM models for activated carbon production and phenol adsorption had R² values of 0.9829 and 0.9113, respectively, with good modeling and optimization outcomes. In summary, the present results show that the olive branches-based activated carbon possesses a high specific surface area and can be successfully used as an adsorbent for toxic aqueous phase pollutants such as phenol under a varying set of process conditions.