Phenol removal from aqueous solutions by nanoporous MCM-41 silica adsorbent modified with diamine group

Phenol and its derivatives are common organic pollutants existing in wastewater of many industries such as oil refineries, coal processing, coking operations, petrochemical, Cementite, resin and plastic manufacturing industries. Correspondingly, Phenol is very toxic for human and environment. In the present study, removal of Phenol from aqueous solution using the mesoporous MCM-41 silica functionalized with diamine group (NH2-MCM-41) was investigated.
This experimental study was done in samples of synthetic and real wastewater from Kerman Cementite factory within six months. The modification of mesoporous MCM-41 materials by grafting diamine functional groups directly to the surface of a solid adsorbent was studied. The structure of the synthesis materials was characterized by XRD, BET and FT-IR. The chemical quality of crude sample and its Phenol was determined and then the influence of pH, absorbent amount and time on the removal of Phenol was evaluated. Then, the optimal conditions for each of these parameters were determined. The same experiments were done for samples of real wastewater. In order to understand the process of adsorption, kinetics of absorption isotherms equilibrium was also studied.
The results showed that increasing the adsorbent dose and contact time led to increasing of the removal efficiency and increasing pH and also the initial phenol concentration led to reducing of removal efficiency. According to the results, the best removal efficiency occurred at acidic pH and adsorption equilibrium time was 45 min. The highest percentage of Phenol adsorption was observed at pH= 6, initial phenol concentration 70 mg/L, adsorbent amount of 10 g/L for synthetic solution with removal efficiency of 73% and for real solution with the efficiency of 71%. The findings revealed that the removal of Phenol followed the freundlich isotherm (R2=98%) and the second order synthetic model (R2=99%).
The results showed that the NH2-MCM-41 materials are effective adsorbents for the Phenol removal from industrial wastewater.