Modeling Selenite Breakthrough with the Pore Surface Diffusion Model in Iron Coated Granular Activated Carbon Packed Bed Columns

Abstract

Iron coated granular activated carbon (Fe-GAC) has been proven to be effective for removing selenite from aqueous solution in batch studies. Design and use of the adsorbent in column settings require understanding the key mass transfer characteristics, which are required for full-scale applications. In this study, rapid small-scale column tests (RSSCTs) were conducted at various empty bed contact times (EBCTs). Pore and surface diffusion model (PSDM) was introduced to predict selenite breakthrough curves of continuous flow packed columns containing iron coated granulated activated carbon. Effluent Se(IV) breakthrough was incipient immediately in the experiment with 0.055-min EBCT, whereas about 780 bed volumes of water at 1.0 mg/L initial concentration of Se(IV) was treated at an EBCT of 0.447 min before breakthrough occurred. The adsorption capacity was estimated using the Freundlich isotherm model. The adsorption results of the selenite on Fe-GAC columns demonstrated that the PSDM can predict the column performance satisfactorily. Full scale column design criteria, such as hydraulic loading rate (HLR), carbon usage rate (CUR), and degree of column utilization (DoCU) were calculated and recommended. .

Iron Oxide-Coated GAC Adsorbents: Diffusion-Controlled Sorption of Selenite

“…The main controlling mass transfer mechanism is pore surface diffusion, which was discussed in another study. 30 On the basis of above information, the modified finite-bath diffusion model fitted the experiments very well, with a diffusion coefficient of 2.9 Â 10 -4 cm 2 /s.…”

“…One possible reason is that the iron oxide-coated layer is more loosely compared with the polymer layer reported by others. The main controlling mass transfer mechanism is pore surface diffusion, which was discussed in another study . On the basis of above information, the modified finite-bath diffusion model fitted the experiments very well, with a diffusion coefficient of 2.9 × 10 −4 cm 2 /s.…”

Remoção de diuron e hexazinona por meio de adsorção em carvão ativado, oxidação e tratamento em ciclo completo

“…Figura 3.5 -Curva de ruptura para adsorção de Selênio em coluna preenchida de óxido de ferro, com valores experimentais e modelo matemático (Yan et al, 2010) Figura 3.6 -Curva de ruptura para adsorção de MON para diferentes tipos de adsorventes. (Othman, 2001) Hand et al (1984) desenvolveram o modelo matemático simplificado de transferência de massa do processo de adsorção, a partir do qual o ERCER foi desenvolvido e validado por Crittenden et al (1986Crittenden et al ( , 1987Crittenden et al ( e 1991…”