Polycyclic aromatic hydrocarbons adsorption from wastewater using different types of prepared mesoporous materials MCM-41in batch and fixed bed column

Abstract

Adsorption techniques were tested for the removal of naphthalene (C10H8) polycyclic aromatic hydrocarbon (PAH) from aqueous solution in a batch and fixed-bed column systems. Three various types of prepared mesoporous silica MCM-41 were investigated such as; calcined, non-calcined (retained templates) and functionalized with amine groups (NH2-MCM-41). It was found that adsorption data resulted from non-calcined and functionalized adsorbents, fitted well with Langmuir and Freundlich adsorption isotherms, respectively. The total adsorption process was fitted with both pseudo-second-order kinetic model and intra-particle diffusion model, successfully. Thermodynamic results specified that the adsorption capacity of C10H8 was reduced with increasing temperature, proving spontaneous nature and exothermic process. In a fixed-bed continuous system, C10H8 was efficiently separated using MCM-41. Breakthrough curves were tested at various bed heights, flow rates, and initial C10H8 concentrations. Thomas and Yoon models were applied to find kinetic constants and to predict naphthalene breakthrough curves. Both non-calcined and functionalized MCM-41 were regenerated five times in a batch system, while calcined MCM-41 was regenerated four times in a fixed-bed system without any significant loss in adsorption capacity and found to be convenient for reuse in consecutive adsorption-desorption cycles. The results suggested that non-calcined and functionalized MCM-41 can be applied as efficient adsorbents for removal of naphthalene from aqueous solution in a batch adsorption system and the calcined MCM-41 in a fixed bed continues system.