704
J. Qu et al. / Journal of Alloys and Compounds 622 (2015) 703–707
The BPA concentrations were determined by high performance liquid chromatogra-
phy (HPLC) after the supernatant was filtered through 0.22 mm Millipore cellulose
acetate membrane. In the experiments, three replicates were carried out.
resistivity and relatively low eddy current losses [11,12]. However,
it is worthy to note that the reactant contents have to be adjusted
with lots of pure reagent when SABs were directly used as precur-
sors. In addition, the synthetic process also affects the performance
of Zn–Mn ferrites [13].
3. Results and discussion
In our previous work, nano materials were successfully
synthesized using some plants [14–17], which could enhance the
efficiencies of photocatalytic degradation on organic pollutant in
3.1. Composition of Zn–Mn SABs
The weight of a set of Zn–Mn SABs used in this work was 24 g.
The composition of main metals in Zn–Mn SABs (Table 1) was
shown as follows: 15.5 2.13% for Zn, 26.7 6.24% for Mn,
0.004 0.001% for Hg, 0.01 0.002% for Cd, 8.52 0.07% for Fe,
0.32 0.11% for Pb, 1.62 0.18% for Cu.
water [18–32]. In this work, a convenient synthesis of ZnxMn1Àx
O
nanoparticles using Zn–Mn SABs was reported and the removal
efficiencies of bisphenol A (BPA, an endocrine disruptor) under
solar light irradiation with them were investigated. These findings
cannot only reduce the cost and simplify the synthesis process of
ZnxMn1ÀxO nanoparticles, but also have positive effects on solving
the recycling of SABs as well as the problem of organic pollutant in
water.
3.2. Characterization of ZnxMn1ÀxO nanoparticles
Fig. 1 showed XRD pattern of the synthesized ZnxMn1ÀxO nano-
particles from Zn–Mn SABs (the dosage of zinc crust was 4 g). All
the diffraction peaks could be well indexed to the hexagonal phase
ZnMnO3 reported in JCPDS card (No. 19-1461). Furthermore, the
broadening at the bottom of diffraction peaks also denoted that
the crystalline sizes were small, and the diffraction peaks were
narrow, which meant that crystalline substances were synthesized
[34].
In the EDS spectrum (Fig. 2) of the synthesized ZnxMn1ÀxO, the
peaks of Zn, Mn, and O were obviously observed. The atom frac-
tions of Zn and Mn were 15.04% and 14.93%, and the ratio of Zn
to Mn was nearly 1:1. So, the Zn0.5Mn0.5O nanoparticles were syn-
2. Material and methods
2.1. Materials
The AA size Zn–Mn SABs (1.5 V) with the same brand and type, used in this
work, were kindly provided by student association named ‘‘Sons of Earth’’ of Bohai
university. The Zn–Mn batteries involved the mass trademarks consumed in China.
The Zn–Mn SABs used in this work was weighed and the contents of main heavy
metals in them were determined using atomic absorption spectrometer after being
digested in aqua regia. The reagents and solvents were A. R. grade materials.
2.2. Pretreatment of SABs and elemental composition
thesized, and it was proposed that the synthesized Zn0.5Mn0.5
O
Zn–Mn SABs were disassembled in following steps: (1) SABs were manually dis-
mantled into scrap (including plastics, copper cap, zinc crust, and carbon rod) and
powder; (2) the powder was added into 150 ml of 0.5 mol LÀ1 sulfuric acid (H2SO4)
and filtrated after being dried (400 °C) for 2 h, crushed, and washed many times
with water; (3) 0.5 mol LÀ1 ammonia (NH3ÁH2O) solution was added into the above
mixture solution (adjust the pH values to 8.0) and filtrated; and (4) the filtrate was
added into 20 ml of 2.5 mol LÀ1 thermal sodium hydroxide (NaOH) solution, fil-
trated, and the formed black residues were collected.
were corresponding to the ZnMnO3 (ZnO and MnO2) structure. In
addition, the weight of the synthesized Zn0.5Mn0.5O nanoparticles
was 13.7 g from a set of Zn–Mn SABs, it meant that the yield was
57.1%.
As shown in Table 1, there were Hg, Cd, Fe, Pb, and Cu in the
Zn–Mn SABs. However, our synthesized Zn0.5Mn0.5O nanoparticles
from Zn–Mn SABs did not include any impurities. The other metals
were removed in the process of synthesis of SABs: (1) the Hg
was volatilized in the dry process (400 °C) for 2 h [3]; (2) the Pb
was formed to PbSO4 (precipitation) with H2SO4 and removed by
filtration; (3) the Cd was formed to Cd(OH)2 (precipitation) under
the condition of the pH values at 8.0 and removed by filtration,
but the Mn(OH)2 was dissolved in solutions containing ammonium
salts [35]; and (4) the Fe was dissolved in thermal NaOH solution,
but undissolved Mn(OH)2 was collected.
To obtain more details of the Zn0.5Mn0.5O nanoparticles struc-
ture from Zn–Mn SABs, the structures of residual frameworks were
characterized by SEM (shown in Fig. 3). The SEM image confirmed
that the Zn0.5Mn0.5O nanoparticles were polydispersed rather than
in uniform distribution. The synthesized Zn0.5Mn0.5O nanoparticles
were cylinder, and the length of the them was 60 nm.
2.3. Synthesis and characterization of ZnxMn1ÀxO nanoparticles
The mashed zinc crust (the weight was about 4 g) of a set of Zn–Mn SABs and
the above black residues were added into 1.25 mol LÀ1 H2SO4 solution containing
2.5 wt% hydrogen peroxide (H2O2) with magnetic stirring at 85 °C until complete
dissolution [33]. Then, the 0.5 mol LÀ1 NH3ÁH2O was added into the mixture to
adjust the pH to 8.5 at 85 °C. The precipitates were filtered after aging for 3 h at
85 °C, washed, and dried at 500 °C for 2 h.
The synthesized ZnxMn1ÀxO nanoparticles were characterized by the follow
methods: X-ray diffraction (XRD) pattern was obtained on a Rigaku D-max C III
(Ni-filtered Al K
a radiation); scanning electron microscopy (SEM) image was per-
formed using a JEOL JSM-840 operated at 3.0 kV; energy dispersive spectrum
(EDS) was obtained using an Oxford EDX system attached to SEM.
In addition, 1 g and 2.5 g mashed zinc crust of Zn–Mn SABs were also used to
synthesize ZnxMn1ÀxO nanoparticles (different proportions of Zn and Mn) in accor-
dance with the above processes.
Afterwards, with the additions of the 1 g and 2.5 g mashed zinc
crust of Zn–Mn SABs, the Zn0.1Mn0.9O and Zn0.3Mn0.7O nanoparticles
2.4. Adsorption and photodegradation experiment
The experimental procedure for the adsorption/desorption and photocatalytic
degradation of BPA under solar light irradiation was carried out as follows: (1)
10 mg synthesized ZnxMn1ÀxO (different proportions of Zn and Mn) nanoparticles
were added into 100 mL aqueous solution of BPA (10 mg LÀ1), respectively. After
continuously stirred and kept in the dark at 25 °C, the supernatant was collected
at different time intervals; (2) 10 mg LÀ1 BPA (100 mL) solution were added in a
pyrex cylindrical vessel and continuously stirred under the solar light irradiation
(using a solar simulator, 150 W Xenon) for 180 min to evaluate the photodegrada-
tion capacities. The distance between the photosource and reactor was 10 cm. At
different time intervals, the supernatant was collected; (3) 10 mg LÀ1 BPA
(100 mL) solution and 10 mg ZnxMn1ÀxO nanoparticles (different proportions of
Zn and Mn) were added in a pyrex cylindrical vessel. After equilibration of adsorp-
tion/desorption for BPA on the surfaces of ZnxMn1ÀxO nanoparticles was completed
in the darkness, the resulted suspensions were continuously stirred under the solar
light irradiation for 180 min. The distance between the photosource and reactor
was 10 cm. At different time intervals, the supernatant was collected; and (4) the
collected supernatant was centrifuged at 5000 rpm for 30 min in the centrifuge.
Table 1
Composition of main metals in Zn–Mn SABs (%).
Metals
Percentage
Zn
Mn
Hg
Cd
Fe
15.5 2.13b
26.7 6.24b
0.004 0.001b
0.01 0.002b
8.52 0.07a
0.32 0.11b
1.62 0.18b
Pb
Cu
The percentages of other elements were not shown. Data were average S.E, n = 3.
a
Significant at P < 0.01.
Significant at P < 0.05.
b