Harendra and Vipulanandan (2008, 2011) have studied the dechlorination of PCE
solubilized in different surfactants by Ni/Fe particles (200 g L
À1 ). The authors have
shown that more than 500 mg L
À1 of PCE can be completely degraded in less than
3 h with a biosurfactant (UH-surfactant, 3.2 g L
À1 ) and in less than 9 h with CTAB
(2.8 g L
À1 ). Degradation with SDS (3.5 g L
À1 ) and TX-100 (1.5 g L
À1 ) is incomplete
even after more than 15 h. Reactions are pseudo-first order, except with TX-100
(1.93) and UH-biosurfactant (1.8).
Shin et al. (2008) have shown that cationic surfactants CTAB, PCP, and CPC
enhanced TCE reduction by ZVI at concentration lower than their respective CMC.
Nonionic surfactants Brij30, Brij35, Brij36, Brij56, and Brij97, and anionic surfactant SDS inhibited degradation. The authors claim that cationic surfactants enhanced
TCE adsorption on iron due to the electrostatic interactions between electronegative
chlorine group and positive head group of the surfactant. For in situ application, low
amounts of cationic surfactants have to be used, as they can potentially contaminate
groundwater.
Zhang et al. (2011) have studied the degradation of soil-sorbed TCE by Pd/Fe
nanoparticles stabilized with carboxymethyl cellulose with cationic HDTMA, nonionic Tween 80 surfactants, and anionic SDS surfactants. They concluded that both
the type of surfactant and soil characteristics had a strong impact on degradation
rates. For a soil with high organic matter contents, degradation rates are strongly
limited by desorption kinetics. The authors have shown that SDS is more effective
for TCE desorption and degradation in water, both at and above its CMC. However,
inhibitory effects were observed for cationic and nonionic surfactants.
Reduction of chlorinated benzenes in presence of surfactant has been studied. Nie
et al. (2012) have shown that HCB dechlorination with bimetallic Ag/Fe particles
(dechlorination rate of 59.5% after 20 min without surfactant) is clearly promoted by
the nonionic surfactant TX-100, with a dechlorination rate improved to 94.1% with
20 mg L
À1 TX-100, and 98.5% with 100 mg L
À1 TX-100. Cationic surfactant
hexadecylpyridinium bromide hydrate (HBH) has to be used at low concentrations,
with an increase to 88.6% at 20 mg L
À1 HBH, but the rate decreases with increasing
the concentration beyond 50 mg L
À1 , showing an inhibitory effect when 400 mg L
À1
were added (41.3% of dechlorination). With anionic surfactant SDBS, the rate
increased with increasing the concentration, and the dechlorination rate reached
91.7% with 400 mg L
À1 SDBS.
Zheng et al. (2009) have shown that TX-100 also improved HCB dechlorination
with Cu/Fe microparticles, especially due to the improvement of HCB mass transfer.
Yuan et al. (2010a) have shown that the dechlorination rate of chlorinated benzenes
with TX-100 and cationic myristylpyridinium bromide (MPB) increased with
increasing hydrophobicity (n Cl > 4), due to the hydrophobic–hydrophilic variation
at the surface of Cu/Fe particles. In field experiment, the dechlorination rate with
surfactant is however impacted by the presence of organic matter (humic acid) and
corrosion inhibitors (Otto et al. 2003; Yuan et al. 2010b).
334
R. Rodrigues et al.
solubilized in different surfactants by Ni/Fe particles (200 g L
À1 ). The authors have
shown that more than 500 mg L
À1 of PCE can be completely degraded in less than
3 h with a biosurfactant (UH-surfactant, 3.2 g L
À1 ) and in less than 9 h with CTAB
(2.8 g L
À1 ). Degradation with SDS (3.5 g L
À1 ) and TX-100 (1.5 g L
À1 ) is incomplete
even after more than 15 h. Reactions are pseudo-first order, except with TX-100
(1.93) and UH-biosurfactant (1.8).
Shin et al. (2008) have shown that cationic surfactants CTAB, PCP, and CPC
enhanced TCE reduction by ZVI at concentration lower than their respective CMC.
Nonionic surfactants Brij30, Brij35, Brij36, Brij56, and Brij97, and anionic surfactant SDS inhibited degradation. The authors claim that cationic surfactants enhanced
TCE adsorption on iron due to the electrostatic interactions between electronegative
chlorine group and positive head group of the surfactant. For in situ application, low
amounts of cationic surfactants have to be used, as they can potentially contaminate
groundwater.
Zhang et al. (2011) have studied the degradation of soil-sorbed TCE by Pd/Fe
nanoparticles stabilized with carboxymethyl cellulose with cationic HDTMA, nonionic Tween 80 surfactants, and anionic SDS surfactants. They concluded that both
the type of surfactant and soil characteristics had a strong impact on degradation
rates. For a soil with high organic matter contents, degradation rates are strongly
limited by desorption kinetics. The authors have shown that SDS is more effective
for TCE desorption and degradation in water, both at and above its CMC. However,
inhibitory effects were observed for cationic and nonionic surfactants.
Reduction of chlorinated benzenes in presence of surfactant has been studied. Nie
et al. (2012) have shown that HCB dechlorination with bimetallic Ag/Fe particles
(dechlorination rate of 59.5% after 20 min without surfactant) is clearly promoted by
the nonionic surfactant TX-100, with a dechlorination rate improved to 94.1% with
20 mg L
À1 TX-100, and 98.5% with 100 mg L
À1 TX-100. Cationic surfactant
hexadecylpyridinium bromide hydrate (HBH) has to be used at low concentrations,
with an increase to 88.6% at 20 mg L
À1 HBH, but the rate decreases with increasing
the concentration beyond 50 mg L
À1 , showing an inhibitory effect when 400 mg L
À1
were added (41.3% of dechlorination). With anionic surfactant SDBS, the rate
increased with increasing the concentration, and the dechlorination rate reached
91.7% with 400 mg L
À1 SDBS.
Zheng et al. (2009) have shown that TX-100 also improved HCB dechlorination
with Cu/Fe microparticles, especially due to the improvement of HCB mass transfer.
Yuan et al. (2010a) have shown that the dechlorination rate of chlorinated benzenes
with TX-100 and cationic myristylpyridinium bromide (MPB) increased with
increasing hydrophobicity (n Cl > 4), due to the hydrophobic–hydrophilic variation
at the surface of Cu/Fe particles. In field experiment, the dechlorination rate with
surfactant is however impacted by the presence of organic matter (humic acid) and
corrosion inhibitors (Otto et al. 2003; Yuan et al. 2010b).
334
R. Rodrigues et al.