Zh. Li et Rs. Bowman, Regeneration of surfactant-modified zeolite after saturation with chromateand perchloroethylene, WATER RES, 35(1), 2001, pp. 322-326
Surfactant-modified zeolites (SMZ) have drawn recent attention as sorbents
due to their removal of multiple types of contaminants and low material cos
t. Hoc-ever, like most sorbents, SMZ has a finite sorption capacity for dif
ferent contaminants. The potential applications, economics, and efficiency
of SR IZ as a sorbent are related to the ability to regenerate the material
, This paper reports several methods to regenerate chromate- and perchloroe
thylene-saturated SMZ. Regeneration of chromate-saturated SMZ was achieved
by Bushing with a sodium carbonate:sodium hydroxide solution. However, this
high-pH solution increased the counterion competition for chromate sorptio
n sites and decreased the chromate sorption capacity of the regenerated SMZ
, As an alternative regeneration method, chromate sorbed to SMZ was reduced
to Cr[II] in situ using sodium dithionite solution. Although reduction wit
h dithionite restored the chromate sorption maximum, the chromate sorption
intensity was lowered, possibly due to the competition by sulfate (generate
d from oxidation of dithionite) for chromate sorption sites. Carbonate-rege
nerated SMZ showed no loss of sorption affinity for perchloroethylene (PCE)
compared to virgin SMZ. Air sparging of PCE-saturated SMZ fully regenerate
d the SMZ. The results show that it is possible to regenerate and re-use SM
Z following saturation with anionic or nonpolar organic contaminants. (C) 2
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