Polycation-Exchanged Clays as Sorbents for Organic Pollutants: Influence of Layer Charge on Pollutant Sorption Capacity
✍ Scribed by C. Breen; R. Watson
- Book ID
- 102581948
- Publisher
- Elsevier Science
- Year
- 1998
- Tongue
- English
- Weight
- 284 KB
- Volume
- 208
- Category
- Article
- ISSN
- 0021-9797
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✦ Synopsis
The uptake curves for the adsorption of a polycation ([CH 2 CH-(OH)CH 2 N(CH 3 ) 2 ] n n؉ (Cl) n n؊ ) onto a low iron Texas bentonite, WL, have been determined and compared with those onto two source smectites, SWy-1 and SAz-1. The polycation exhibited a marked affinity for all the smectite surfaces but polycation uptake was maximized on the fine fractions of Na ؉ -WL. Variable temperature X-ray diffraction of the clay polycation complexes showed that the polycation was segregated into different interlayers at loadings below 30% of the CEC. The adsorption of benzene onto TMA ؉ -exchanged SWy-1, SAz-1, and WL showed that, despite having a comparable layer charge to SWy-1, WL was as poor a sorbent for benzene as SAz-1, which has a much higher layer charge. The adsorption of p-nitrophenol (PNP) from aqueous solution onto the TMA ؉ -exchanged sorbents exhibited the same trends, although a smaller amount was adsorbed due to the greater size of PNP. The amount of PNP adsorbed by polycation-treated SWy-1 depended upon the polycation loading, and PNP uptake maximized at loadings of 28 and 46 mg (g clay) ؊1 . At higher loadings (80, 102, and 147 mg (g clay) ؊1 ) the uptake curves became linear and the PNP uptake decreased with increased polycation loading. No polycation-treated clay was as effective as TMA ؉ -exchanged SWy-1 for the removal of PNP from water.