Oxidative debromination and degradation of tetrabromo-bisphenol A by a functionalized silica-supported iron(III)-tetrakis(p-sulfonatophenyl)porphyrin catalyst

Article abstract of DOI:10.3390/molecules18055360

Tetrabromobisphenol A (TBBPA), a commonly used brominated flame retardant, also functions as an endocrine disruptor. Thus, the degradation of TBBPA has attracted considerable interest among the scientific community. Iron(III)-porphyrin complexes are generally regarded as green catalysts and have been reported to catalyze the efficient degradation and dehalogenation of halogenated phenols in environmental wastewaters. However, they are quickly deactivated due to self-degradation in the presence of an oxygen donor, such as KHSO₅. In the present study, an iron(III)-tetrakis (p-sulfonatophenyl)-porphyrin (FeTPPS) was immobilized on imidazole-modified silica (FeTPPS/IPS) via coordination of the Fe(III) with the nitrogen atom in imidazole to suppress self-degradation and thus enhance the catalyst reusability. The oxidative degradation and debromination of TBBPA and the influence of humic acid (HA), a major component in leachates, on the oxidation of TBBPA was investigated. More than 95% of the TBBPA was degraded in the pH range from 3 to 8 in the absence of HA, while the optimal pH for the reaction was at pH 8 in the presence of HA. Although the rate of degradation was decreased in the presence of HA, over 95% of the TBBPA was degraded within 12 h in the presence of 28 mg-C L^-1 of HA. At pH 8, the FeTPPS/IPS catalyst could be reused up to 10 times without any detectable loss of activity for TBBPA for degradation and debromination, even in the presence of HA.

Full text of DOI:10.3390/molecules18055360

Molecules 2013, 18, 5360-5372; doi:10.3390/molecules18055360
OPEN ACCESS
molecules
ISSN 1420-3049
www.mdpi.com/journal/molecules
Article
Oxidative Debromination and Degradation of
Tetrabromo-bisphenol A by a Functionalized Silica-Supported
Iron(III)-tetrakis(p-sulfonatophenyl)porphyrin Catalyst
Qianqian Zhu, Yusuke Mizutani, Shohei Maeno and Masami Fukushima *
Laboratory of Chemical Resources, Division of Sustainable Resources Engineering,
Graduate School of Engineering, Hokkaido University, Sapporo 060-8628, Japan
* Author to whom correspondence should be addressed; E-Mail: m-fukush@eng.hokudai.ac.jp;
Tel./Fax: +81-11-706-6304.
Received: 15 April 2013; in revised form: 7 May 2013 / Accepted: 7 May 2013 /
Published: 10 May 2013
Abstract: Tetrabromobisphenol A (TBBPA), a commonly used brominated flame
retardant, also functions as an endocrine disruptor. Thus, the degradation of TBBPA has
attracted considerable interest among the scientific community. Iron(III)-porphyrin
complexes are generally regarded as “green” catalysts and have been reported to catalyze
the efficient degradation and dehalogenation of halogenated phenols in environmental
wastewaters. However, they are quickly deactivated due to self-degradation in the presence
of an oxygen donor, such as KHSO5. In the present study, an iron(III)-tetrakis
(p-sulfonatophenyl)-porphyrin (FeTPPS) was immobilized on imidazole-modified silica
(FeTPPS/IPS) via coordination of the Fe(III) with the nitrogen atom in imidazole to
suppress self-degradation and thus enhance the catalyst reusability. The oxidative
degradation and debromination of TBBPA and the influence of humic acid (HA), a major
component in leachates, on the oxidation of TBBPA was investigated. More than 95% of the
TBBPA was degraded in the pH range from 3 to 8 in the absence of HA, while the optimal pH
for the reaction was at pH 8 in the presence of HA. Although the rate of degradation was
decreased in the presence of HA, over 95% of the TBBPA was degraded within 12 h in the
presence of 28 mg-C L−1 of HA. At pH 8, the FeTPPS/IPS catalyst could be reused up to
10 times without any detectable loss of activity for TBBPA for degradation and
debromination, even in the presence of HA.

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Keywords: iron(III)-porphyrin; humic acid; silica support; catalytic oxidation;
tetrabromobisphenol A
1. Introduction
Tetrabromobisphenol A (TBBPA), a widely used brominated flame retardant (BFR), is used in the
treatment of paper, textiles, plastics, electronic equipment, upholstered furniture and chiefly in epoxy
resins that are used in circuit board laminates [1]. The leaching of BFRs, as well as TBBPA, from
wastes derived from such materials in landfills is facilitated in the presence of humic acid (HA), which
is a major component in landfill leachates [2,3]. Many studies have shown that TBBPA can induce
cytotoxicity and hepatotoxicity, and it has the potential to disrupt estrogen signaling [4], therefore, the
development of effective methods for removing TBBPA from landfill leachates is an important issue.
Methods have been reported for oxidative degradation of TBBPA (e.g., birnessite oxidation [5],
photooxidation [6] and permanganate oxidation [7]), but most involve the cleavage of the β-carbon in
TBBPA, and not debromination. In addition, the influence of other contaminants, such as HAs, on
TBBPA oxidation has not been investigated in detail, even though it is well known that HAs are major
components of landfill leachates.
Considerable interest has developed regarding Fe-based biomimetic catalysts, such as iron-porphyrins,
because of their ability to mimic cytochrome P450 enzymes that catalyze a variety of oxidation
reactions [8,9]. Iron porphyrins can oxidize bromophenols in homogenous solutions [10,11], but these
types of catalysts are deactivated due to rapid self-degradation under the highly oxidative conditions
and by dimerization via the formation of μ-oxo iron(III) species [12–14]. The immobilization of such
catalysts on a suitable support has been used to increase their stability towards oxidative self-
degradation and to prevent catalyst deactivation caused by dimerization [15–22]. Among the supports
used to immobilize metalloporphyrins, inorganic supports such as SiO2 are preferred, because of its
low cost, availability, mechanical robustness and chemical inertness.
In a previous study, our research group examined the degradation of TBBPA using a homogeneous
iron(III)-porphyrin catalytic system. The findings indicated that the oxidation was not efficient and no
debromination was observed because the catalyst underwent self-degradation and inhibition by
contaminating HA [10]. Although the immobilization of anionic iron(III)-porphyrins on an
anion-exchange resin was examined, the catalytic activity for 2,6-dibromophenol oxidation decreased
because of anion-exchange reactions between iron(III)-porphyrin and HA, 2,6-dibromophenol or
oxidation products derived from it [23]. In addition, the positively charged surface of the
anion-exchange resin can also adsorb anionic HA, which results in a decrease in degradation
performance. However, nitrogen atoms that are included in the functional groups of the anion-
exchange resins can serve as a ligand for coordination with iron(III). If the iron(III) in the anionic
porphyrin could be tightly attached to the nitrogen atom on the support by coordination, the surface
potentials of the solid catalysts would be changed to negative after complexation. Using such a type of
the solid catalyst, the adsorption of anionic concomitants, such as HAs, would be suppressed, thus
producing a stabile form of iron(III)-porphyrin catalyst on the support.

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In the present study, an anionic iron(III)-tetrakis(p-sulfonatephenyl)porphyrin (FeTPPS) immobilized
on silica modified with an imidazole was examined for use as a catalyst for the enhanced degradation
and debromination of TBBPA in the presence of HA. In addition, the influence of HA on the rate of
TBBPA degradation, debromination and reusability were investigated.
2. Results and Discussion
2.1. Characterization of FeTPPS / IPS
The amount of FeTPPS molecules bound to the surface of the 3-(1-imidazolyl)propylcarbamoyl-3′-
aminopropylsilica (IPS) was estimated by the change in absorbance at 394 nm of the Soret band in
UV-visible absorption spectra. The relative absorption at a wavelength of 394 nm (corresponding to
the Soret band of FeTPPS) between a stock solution of FeTPPS and the solution obtained after
removing the FeTPPS/IPS was used to determine the concentration of FeTPPS molecules bound to the
IPS. The findings indicated that 32.7 mol of FeTPPS was immobilized on 1 g of IPS.
FT-IR spectra of silica, IPS and FeTPPS/IPS are shown in Figure 1. The FT-IR spectrum of IPS
contained characteristic vibration bands in the 2800–3000 cm−1 region, corresponding to symmetrical
and asymmetrical C-H stretching vibrations. The absorbance in the 1400–1600 cm−1 region is assigned
to C=C, C=N ring stretching (skeletal bands) as well as the C=O stretching vibration which was
observed in the FT-IR spectra of IPS and FeTPPS/IPS.
Figure 1. FT-IR spectra of silica gel, IPS and FeTPPS / IPS with KBr pellet.
The change in the surface chemistry of the catalyst was characterized by zeta potential analysis,
which is related to the surface charge (Figure 2). The unmodified silica had a negative zeta potential in
the pH range of 3 to 9, which reflected a large negative surface charge due to the presence of
deprotonated silanol groups. The FeTPPS/IPS catalyst had a negative zeta potential at pH values above
7.1. The FeTPPS/IPS catalyst had a positive zeta potential below pH 7.1, which can be attributed to the
protonation of uncomplexed imidazole group in IPS. The zeta potential verse pH curve (● in Figure 2)

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for the reused catalyst was similar with fresh catalyst (■ in Figure 2). However, the magnitude of the
zeta potential was increased in the pH range from 3 to 9, compared with the fresh catalyst. In addition,
the point of zero charge (PZC) was shifted from pH 7.1 to 7.5 as a result of recycling. This may be due
to the release and degradation of some FeTPPS during the oxidation reaction.
Figure 2. The pH dependence on the Zeta potential for silica, FeTPPS/IPS and the
FeTPPS/IPS that was reused 5 times.
2.2. Influence of pH on the Degradation of TBBPA
Since the pH was not only related to the redox potential of the oxidant but also to species
distribution of TBBPA and other concomitants in aqueous solutions, the influence of pH on the
degradation of TBBPA was investigated. In the absence of HA, the degradation of TBBPA was not
dependent on the pH of the solution. However, in the presence of HA, the reaction was clearly pH
dependent, and the presence of HA also affected the degradation reaction. As shown in Figure 3a, in
the presence of HA, the percentage of degraded TBBPA increased with increasing pH and the highest
degradation performance was observed at pH 8, where more than 95% the TBBPA was degraded in the
presence of HA, indicating that the oxidative degradation of TBBPA is inhibited by HA. This
inhibition was enhanced in the lower pH range and became weaker at higher pH. The zeta potential of
the FeTPPS/IPS indicated that the catalyst had negative surface charge at pH values above 7.1 and a
positive surface charge at pH values below 7.1. Because HA has a large amount of negative surface
charge [24], it can easily be adsorbed on the FeTPPS/IPS surface at a pH below 7.1. The interaction of
TBBPA with catalytic sites could be blocked due to the adsorption of HA at a pH lower than 7. The
surface charge of the catalyst changed to negative at pH values higher than 7.1. In this pH range, the
HA appears to be excluded from the catalyst surface by electrostatic repulsion. Therefore, the
inhibition by HA became weaker in a high pH range. Debromination was observed during the
oxidation reaction in the pH range from pH 4 to 8 (Figure 3b). Although, in a previous study, no
debromination was observed in the case of a homogeneous system [10], Br− was clearly detected in the
reaction mixture in the FeTPPS/IPS catalytic system. The low pH condition was beneficial for
debromination, especially in the absence of HA, and the highest debromination value was found at pH 4.
The highest rate of debromination was also observed at pH 4 in the presence of HA. However,

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compared with HA free conditions, the extent of debromination decreased in the presence of HA due
to the drastic decrease in the rate of degradation of TBBPA. At pH 6 and 7, debromination was
enhanced by HA, even the degradation of TBBPA was inhibited by HA. At pH 8, although the rate of
debromination decreased slightly in the presence of HA, the percent TBBPA degradation was the
highest in the pH range from 3 to 8 in the presence or absence of HA. In addition, the typical pH range
for a leachate is reported to be 6.7–12 [2,3]. Therefore, the influence of HA and catalyst concentration
on the degradation of TBBPA were examined at pH 8.
Figure 3. (a) Influence of pH on percentage TBBPA degradation (b) Influence of pH on
debromination. The reaction conditions were as follow: [TBBPA]0, 50 M; [FeTPPS/IPS],
10 M (0.3 g L−1); [KHSO5], 1.0 mM; [HAs], 25 mg L−1; temperature, 25 °C; reaction
time, 4 h.
To identify the oxidation products produced in the reactions, n-hexane extracts of reaction mixtures
were analyzed by GC/MS for the 1.5-h and 5-h reaction periods. Figure 4 shows one of the
chromatograms for an n-hexane extract of reaction mixtures at pH 8 in the presence of HA. For the
1.5 h reaction period, the peak at 17.8 min of retention time was detected as a major oxidation product
(Figure 4a). This peak was assigned as 4-(2-hydroxyisopropyl)-2,6-dibromophenol (2HIP-2,6DBP)
acetate from the mass spectrum: m/z [relative intensity, fragment identify], 352 [2.65, M+], 310 [30.8,
+
(M−CH2CO)+], 295 [100, (M−CH3CH2CO)+], 252 [48.3, C6H4OBr2 ]. However, 2HIP-2,6DBP
decreased for the 5 h reaction period, and the peak at 53.0 min of the retention time significantly
increased (Figure 4b). This peak was assigned as the trimer of 2,6-dibromophenol and the mass
spectral identification was as follows: m/z [relative intensity, fragment identify], 836 [71.0, M+], 794
+
[100, (M−CH2CO)+], 779 [44.2, (M−CH3CH2CO)+], 756 [48.3, (M−Br)+], 293 [14.8, C6H2(CH3CO2)Br2 ],
+
267 [28.8, C6H2O(OH)Br2 ]. The retention time and mass spectrum of 2HIP-2,6DBP acetate in the
reaction mixtures were in good agreement with those for the acetate of the standard sample. In
previous reports of TBBPA oxidation [5,6], while 2HIP-2,6DBP was found as one of the main
byproducts, 2,6-dibromo-p-benzoquinone (2,6DBQ) was also detected as a main byproduct. However,
no 2,6DBQ was found in the homogeneous FeTPPS-KHSO5 catalytic system [10], even at pH 4 and 6

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as well as at pH 8 for any of the reaction periods. The patterns of oxidation products were also not
varied by solution pH (for at pH 4 and 6) for the heterogeneous FeTPPS/IPS-KHSO5 catalytic system.
Figure 4. GC/MS chromatograms of n-hexane extract from the reaction mixture at
pH 8 in the presence of HA. Reaction period (a) 1.5 h, (b) 5 h. Reaction conditions:
[TBBPA]0, 50 M; [FeTPPS/IPS], 10 M (0.3 g L−1); [KHSO5], 1.0 mM; [HAs], 25 mg L−1,
temperature 25 °C.
2.3. Influence of Catalyst Concentration on the TBBPA Degradation and Debromination
Figure 5 shows the influence of catalyst concentration on the degradation of and debromination of
TBBPA, in which the Δ[TBBPA] represents the concentration of degraded TBBPA. A 0.7–3.4%
decrease in the concentration of TBBPA was found in the presence of the FeTPPS/IPS (10–34 μM)
without KHSO5. These results suggest that the contribution of TBBPA adsorption to the solid catalyst
is minor in the case of Δ[TBBPA]. The Δ[TBBPA] steeply increased up to a concentration of 3.5 μM
of the FeTPPS/IPS catalyst, and then gradually increased at concentrations up to 34 μM (Figure 5a). In
the absence of the solid catalyst, a small amount of TBBPA degradation (3 μM) and Br− release (4 μM)
was observed for a 35 min reaction period. For the debromination (Figure 5b), the concentration of the
released Br− reached a plateau of 3.5–17 μM of the FeTPPS/IPS catalyst, but decreased at 34 μM.
These results indicate that the presence of the catalyst enhances the degradation of TBBPA. The decrease
in debromination at a FeTPPS/IPS concentration of 34 μM may be due to the enhanced oxidation of Br−
at higher catalyst concentrations. The turn over number for TBBPA degradation and debromination, as
estimated for 3.5 μM of the FeTPPS/IPS catalyst, was 7.3 ± 0.3 and 5.1 ± 0.1, respectively.

Molecules 2013, 18
Figure 5. Influence of FeTPPS/IPS concentration on the (a) degradation and (b)
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debromination of TBBPA. [TBBPA]0, 50 μM; pH = 8; [KHSO5], 1 mM; temperature,
25 °C; reaction time, 35 min. The FeTPPS/IPS concentration at 0.3 g L−1 corresponds to
10 M.
2.4. Influence of HA Concentration
HA is present at levels of 20–200 mg-C L−1 levels in landfill leachates [3], and HA can affect the
distribution and oxidation reactions of organic pollutants. The influence of HA concentration was
examined to assess the practical use of the FeTPPS/IPS catalyst. The pseudo-first-order rate constant
(kobs) of TBBPA decreased with increasing concentration of HA. When the HA concentration
increased from 2.8 to 14 mg-C L−1, the kobs dramatically decreased from 1.6 to 0.3 h−1. With a further
increase in the concentration of HA, the kobs decreased further. From the insert in Figure 6, a drop-off
in the initial degradation rate was observed with a small (2.8 mg-C L−1) mount of HA. However, when
the reaction time was prolonged, the percent degradation TBBPA rapidly reached values higher than
95% within 5 h in the case of an HA concentration lower than 14 mg-C L−1. Over 95% the TBBPA
was degraded within 9 h for HA concentrations of up to 29 mg-C L−1. Even in the presence of high
concentrations of HA, 58–87 mg-C L−1, over 75% of the TBBPA was degraded within 12 h.
Figure 6. Influence of HA concentration on the pseudo-first-order rate constant (kobs) for
TBBPA degradation and variations in the percent TBBPA degradation (insertion). The
reaction conditions were as follow: [TBBPA]0, 50 M; [FeTPPS/IPS], 10 M (0.3 g L−1);
[KHSO5], 1.0 mM; pH = 8; temperature, 25 °C.

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2.5. Reusability of FeTPPS/IPS
In terms of using FeTPPS/IPS for water treatment, catalyst reusability is an important factor from
the economical point of view. After each reaction, the catalyst was isolated on a filter, and then washed
with deionized water and acetone. The catalyst had a high degree of durability as demonstrated by the
recyclability test shown in Figure 7a. Over 95% of the TBBPA was degraded in the presence or
absence of HA after five recyclings and more than 85% of the TBBPA was degraded after ten recyclings.
The reused catalyst exhibited a good catalytic activity up to ten catalytic runs with only a small loss
in degradation efficiency. The debromination was around 0.4 ([Br−]/Δ[TBBPA]) during the
recyclability test (Figure 7b). However, the zeta potential of the FeTPPS/IPS increased slightly after
five recyclings, as shown in Figure 2. At pH 8, the zeta potential of the reused catalyst was −6 mV and
the fresh catalyst was −30 mV, indicating that the negative surface charge of the catalyst had decreased
after the recyclability test. The HA would be predicted to be easily absorbed on the reused catalyst
surface due to the change in surface charge, which would have an adverse impact on the degradation of
TBBPA in the presence of HA. Therefore, with increasing catalyst reuse, the inhibition by HA became
a larger issue (Figure 7a). The surface area of the reused catalyst (194 ± 10 m2 g−1) was similar to that
for the fresh catalyst (215 ± 6 m2 g−1). In addition, Figure 8 shows Diffuse Reflectance UV-vis spectra
for the fresh catalyst and after being used for five cycles. The fresh catalyst showed two peaks at
409 nm and 550 nm. After five recyclings, all of the peaks remained, indicating that the structure of the
FeTPPS remained intact during the oxidative degradation reaction. These results show that the higher
catalytic activity of FeTPPS/IPS catalyst was retained after several recyclings.
Figure 7. Reusability of the catalyst (a) TBBPA degradation, (b) number of bromide ions
released. The reaction conditions were as follow: [TBBPA]0, 50 M; [FeTPPS / IPS],
10 M (0.3 g L−1); [KHSO5], 1.0 mM; [HAs], 25 mg L−1; temperature, 25 °C; pH = 8;
reaction time, 4 h (in the absence of HA), 20 h (in the presence of HA).

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Figure 8. Diffuse reflectance UV-vis spectra for the FeTPPS/IPS catalyst before and after
five recyclings.
3. Experimental
3.1. Materials
The soil humic acid (SHA) sample used in this study was extracted from Shinshinotsu peat soil, as
described in a previous report [25]. Tetrabromobisphenol A (TBBPA), 3-isocyanatopropyltrimethoxysilane
and N-(3-aminopropyl)imidazole, were purchased from Tokyo Chemical Industry (Tokyo, Japan).
FeTPPS was synthesized according to the reported procedure [26]. KHSO5 was obtained as a triple
salt, 2KHSO5·KHSO4·K2SO4 (Merck, Darmstadt, Germany).
3.2. Synthesis of Silica Supported FeTPPS Catalyst
Scheme 1 shows the strategy used in the synthesis of the catalyst. The silica gel supported
Fe(III)TPPS catalyst was synthesized by a previously reported method [18], with minor modifications.
In a 2-neck flask, (3-isocyanatopropyl)triethoxysilane (1.3 mL) and N-(3-aminopropyl) imidazole (700 L)
were added to dioxane (20 mL) to synthesize 3-(1-imidazolyl)propylcarbamoyl-3′-aminopropyl-
triethoxysilane. The mixture was stirred for 12 h at 70 °C. Subsequently, 1.5 g of silica gel (10–40 mesh,
Wako Pure Chemicals, Osaka, Japan) was added, and the mixture was stirred at 80 °C for 12 h. The
resulting solid was collected on a filter and consecutively washed with 0.5 M HCl, H2O, 0.1 M NaOH
and finally washed with H2O. The 3-(1-imidazolyl)propylcarbamoyl-3′-aminopropylsilica (IPS) was
then carefully dried overnight in vacuum oven at 50 °C. In a 100 mL flask, IPS (0.5 g) was added to
FeTPPS solution (3.0 mM, 15 mL). The mixture was shaken at 25 °C, 150 rpm under 24 h in the dark.
After the reaction, the FeTPPS/IPS was collected and washed with 1 M NaCl solution, ultra-pure water,
and dried under vacuum.

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Scheme 1. The synthesis of IPS and FeTPPS/IPS.
3.3. Characterization of the Synthesized Catalyst
The catalyst loading amount was estimated using UV-visible absorption spectroscopy. UV-visible
absorption spectroscopy and Diffuse Reflectance UV-vis spectra were obtained using a V-630 type
spectrophotometer (Japan Spectroscopic Co. Ltd., Japan). FT-IR spectra were recorded using an FT/IR
600 type spectrometer (Japan Spectroscopic Co. Ltd.) with KBr pellets. The specific surface areas of
the samples were obtained from N2 sorption isotherm at 77 K using a Beckman Coulter SA3100 (Brea,
CA, USA). Zeta potentials were recorded using a Zetasizer Nano ZS90 (Malvern Instruments Ltd.,
Worcestershire, UK).
3.4. Assay for TBBPA Degradation
A 10 mL aliquot of a 0.02 M citrate/phosphate buffer at pH 4–8 was placed in a 100-mL
Erlenmeyer flask. An aliquot (50 μL) of 0.01 M TBBPA in acetonitrile and the FeTPPS/IPS (3 mg)
was then added to the buffer. Subsequently, aqueous solutions of 1,000 mg L−1 HA in 0.05 M NaOH
solution and 0.1 M aqueous potassium monopersulfate (KHSO5, 100 μL) were added, and the flask
was then allowed to shake at 25 °C in an incubator. After the reaction, the concentrations of the
remained TBBPA were measured by an HPLC with a UV detector. The separation of TBBPA in the
reaction mixture was accomplished with a COSMOSIL 5C18-AR-II column (4.6 mmø × 250 mm). The
mobile phase consisted of a mixture of methanol and 0.08% of H3PO4 aqueous (78/22, v/v). The flow
rate of the eluent and the detection wavelength were set to 1.0 mL min−1 and at 220 nm, respectively.
The released Br− was analyzed by ion chromatography (ICS-90 type, Dionex). The mobile phase was
an aqueous mixture of 2.7 mM Na2CO3 and 0.3 mM NaHCO3, and the flow rate of the eluent was set
at 1.5 mL min−1. The degradation percent of TBBPA was calculated by the following equation:

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where [TBBPA]0 and [TBBPA]t represent the TBBPA concentrations remained in the reaction mixture
before and after a t-h reaction period, respectively. The pseudo first-order reaction rate constant, kobs
(h−1), was estimated by non-linear least square regression analysis of the dataset for reaction time (h)
and [TBBPA]t/[TBBPA]0 to below equation:
The turnover number for TBBPA degradation and debromination was calculated by dividing the
concentration of degraded TBBPA (Δ[TBBPA] = [TBBPA]0 − [TBBPA]t) or released Br− by the
catalyst concentration.
For the analysis of oxidation products, 1 M aqueous ascorbic acid (1 mL) was added, and pH of the
solution was adjusted to 11–11.5 by adding aqueous K2CO3 (600 g L−1). Subsequently, acetic anhydride
(5 mL) was added dropwise to the solution, and a 1 mM anthracene solution in hexane (0.5 mL) was
added as an internal standard (ISTD) for the GC/MS analysis. This mixture was doubly extracted with
n-hexane (10 mL), and the extract was then dried over anhydrous Na2SO4. After filtration, the extract
was evaporated under a stream of dry N2, and the residue was dissolved in n-hexane (0.25 mL). An
aliquot of the extract (1 μL) was introduced into a GC-17A/QP5050 GC/MS system (Shimadzu, Kyoto,
Japan). A Quadrex methyl silicon capillary column (0.25 mm id × 25 m) was employed in the
separation. The temperature ramp was as follows: 65 °C for 1.5 min, 65–120 °C at 35 °C min−1,
120–300 °C at 4 °C min−1 and a 300 °C held for 10 min.
4. Conclusions
A FeTPPS/IPS catalyst was synthesized and its use in the degradation and debromination of
TBBPA in the absence and presence of HA, a major component of leachates, was examined. This
catalytic system was pH independent in the absence of HA and the highest catalytic activity was found
to be at pH 8 in the presence of HA. Although the presence of HA retarded the degradation of TBBPA,
over 95% of the TBBPA was degraded in the case of HA 28 mg-C L−1. In addition, FeTPPS/IPS
exhibited good catalytic activity for up to ten recyclings. As a green and efficient catalyst, FeTPPS/IPS
has promise for use in the field of pollution control.
Acknowledgments
This work was supported by Grants-in-Aid for Scientific Research from the Japan Society for the
Promotion of Science (21310048).
Conflict of Interest
The authors declare no conflict of interest.

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Sample Availability: Samples of the compounds are available from the authors.
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