AWWA ACE94136

In order to better understand the relation between granular activated carbon (GAC) pore structure and adsorption behavior, six GACs of differing pore structures were characterized by their aqueous-phase adsorption capacity for five adsorbates of various molecular sizes. The adsorbates included iodine, p-nitrophenol and three organic dyes: Methylene Blue, Crystal Violet and Congo Red. The adsorption behavior of iodine and p-nitrophenol were believed to parallel the field adsorption behavior of small synthetic compounds, whereas the dyes were expected to behave similarly to the fulvic and small humic compounds of natural TOC. The adsorption behavior of these compounds was effectively correlated with pore size distributions obtained by analysis of N2 adsorption isotherms at 77 K using two models. The first is the Barret, Joyner and Halenda (BJH) model which characterizes the total micropore volume and the mesopore volume distribution. The second is the newly-developed density functional theory (DFT) model. The DFT model appeared to provide the better correlations to dye adsorption behavior although it also appeared to contain an over-simplification that flawed the data interpretation in the 8-14 A pore width range. The research conducted herein provides significant evidence that specific pore sizes involved for adsorbing organic molecules from the aqueous phase. The range of pore sizes involved in adsorption is dependent, in part, on the size of the adsorbing molecule.

Product Details

Published:

01/01/1994

ISBN(s):

0898677742

Number of Pages:

42

File Size:

1 file , 1.4 MB