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Elevated degradation of di-n–butyl phthalate by activating peroxymonosulfate over GO–CoFe2O4 composites: Synergistic effects and mechanisms
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Qingliang Liu, Hang Qie, Zhiqiang Sun, Yufei Zhen, Liying Wu, Ying Zhao*, Jun Ma
Chinese Chemical Letters | 2023, 34(12) : 108397
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Chinese Chemical Letters | 2023, 34(12): 108397
• Communication •
Elevated degradation of di-n–butyl phthalate by activating peroxymonosulfate over GO–CoFe2O4 composites: Synergistic effects and mechanisms
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Qingliang Liu, Hang Qie, Zhiqiang Sun, Yufei Zhen, Liying Wu, Ying Zhao*, Jun Ma
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  • State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China
Published: 2023-12-15 doi: 10.1016/j.cclet.2023.108397
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Rational design of heterogeneous catalysts with high activity and stability is crucial in peroxymonosulfate (PMS)-based oxidation treatment of wastewater. Herein, the graphite oxide-cobalt ferrite (GO-CoFe2O4) composite was constructed, and its morphological, component and structural characteristics were thoroughly examined, respectively. GO-CoFe2O4 obviously boosted PMS catalytic performance on di-n–butyl phthalate removal (DBP, RDBP = 90%, RTOC = 37%), which indicated by the first-order kinetic constant (kDBP = 0.060 min−1) being roughly 4 times than pure CoFe2O4 (kDBP = 0.015 min−1). The fabrication of GO-CoFe2O4 brought the favorable stability and repeatability up to six cycles. Moreover, the method of batch dosing catalyst was creatively proposed to improve the PMS utilization efficiency. The coupling of GO enhanced the dispersion of CoFe2O4 particles to obtain sufficient active sites, additionally, the plentiful C=O groups and free-flowing electrons on GO promoted GO-CoFe2O4 to coordinate a redox process during PMS activation. With the aid of theoretical calculations, GO-CoFe2O4 was revealed to exhibit a strong affinity toward PMS adsorption, where PMS spontaneously dissociated into sulfate radical (SO4•−), hydroxyl radical (•OH) and singlet oxygen (1O2), acting as the reactive oxygen species (ROSs). Electrons cycling between Co, Fe and O species ensured continuous ROSs generation and excellent catalytic performance.

Peroxymonosulfate  /  Cobalt ferrite  /  Graphene oxide  /  Synergistic effect  /  Di-n–butyl phthalate
Qingliang Liu, Hang Qie, Zhiqiang Sun, Yufei Zhen, Liying Wu, Ying Zhao, Jun Ma. Elevated degradation of di-n–butyl phthalate by activating peroxymonosulfate over GO–CoFe2O4 composites: Synergistic effects and mechanisms[J]. Chinese Chemical Letters, 2023 , 34 (12) : 108397 - . DOI: 10.1016/j.cclet.2023.108397
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Di-n–butyl phthalate (DBP), a typical kind of phthalate esters, has been considered a priority controlled hazardous contaminant by U.S. EPA. It occurs at low concentrations in aquatic environments and poses considerable risk of endocrine-disrupting effects and metabolic disorders to human beings [1,2]. Moreover, the biodegradation kinetics of DBP are very slow in the natural environment, from dozens of days to more than 20 years [3]. Presently, the typical treatments, including adsorption, membrane separation, biodegradation as well as chemical oxidation, suffer from different drawbacks with regard to their remedy time scale and large energy consumption [4]. Consequently, it is highly demanded to explore a cost-efficient strategy for eliminating trace-level DBP.
Sulfate radical (SO4•−)-based advanced oxidation processes (SR-AOPs) exhibit a favorable standard reduction potential (2.5–3.1 V vs. NHE), wide pH adaptability (2.0–9.0), longer half-life with regard to the hydroxyl radical (30–40 µs vs. 20 ns) and high oxidation selectivity [5]. These make it possible to employ SR-AOPs to decompose a variety of organic substances in sewage. SO4•− can be effectively generated by activating peroxymonosulfate (PMS) in conjunction with ultrasound, photolysis, heat, homogenous or heterogeneous catalysts [6]. Cobalt-based catalysts have been investigated, and it has been discovered that they are the most effective activators for cleaving the O—O bond in an asymmetric PMS structure [7]. Cobalt ferrite (CoFe2O4) belonging to the spinel-type ferrites family (S.G. Fd-3m) has indicated high activity and magnetic properties with excellent stability in order to degrade persistent pollutants [8]. The coupling effect between Co and Fe species might be more effective as a catalyst in PMS activation than their single component equivalent. Simultaneously, CoFe2O4 is characterized to have a high abundance of oxygen vacancies and surface hydroxyl groups, which also help to further activate PMS [9]. Ren et al. evaluated the performance of MFe2O4 (M = Co, Cu, Mn, Zn) in PMS activation, and concluded that CoFe2O4 showed higher catalytic activity toward PMS for the degradation of DBP, and all catalysts displayed excellent recycling and stability in the repeated batch experiment [10]. Nonetheless, the unprotected CoFe2O4 primary nanoparticles are prone to agglomeration, as a result, there are fewer active sites that are accessible and there is less dispersion in the reaction solution, which further reduces the effectiveness of PMS activation and organics decomposition [11]. Therefore, it is necessary to disperse CoFe2O4 on supporters for stable and efficient catalytic performance.
Recently, carbon-based materials were used to supporters for transition metal-based catalysts to fabricate carbon-loaded metal composites. Two-dimensional graphene oxide (GO) is a substance with various excellent properties of unique mechanical strength, high electrical conductivity and large specific surface area [12]. Multiple oxygen-containing functional groups including hydroxyl, carboxyl and epoxy situate at the basal plane and the edges of GO [13]. Metal components can be immobilized by such surface functionalization to create a solid structure and promote the separation and dispersion of spinel ferrite particles [14]. Furthermore, GO consists of the hexagonal ring-based carbon network with both sp2- and sp3-hybridized carbon atoms, the free-flowing unpaired electrons from the sp2-hybridized carbon network promote electron transport between particles, further enhancing the catalytic PMS efficiency [15]. These specific surfaces structure of GO make it stand out as a suitable supporter [16]. Although, GO has been used to couple with some metal oxides such as Fe2O3, TiO2, CoOx, CoFeNi LDH, and even spinel ferrite [17-20]. However, rarely has the combination of GO and CoFe2O4 been reported for heterogeneous catalytic PMS. Particularly, the improving mechanism of GO-CoFe2O4 composites on catalytic PMS needs to be investigated, with a focus on the function of GO and the interaction between GO and CoFe2O4.
Herein, a series of GO-CoFe2O4 composites were fabricated and introduced to catalyze PMS for DBP removal. The degrading behavior and physicochemical properties were taken into consideration when choosing the optimized synthesis faction of catalyst. The impacts of different operational parameters, such as catalyst dosage, PMS concentration, initial DBP concentration and initial pH on the activity of GO-CoFe2O4/PMS system were systematically explored. The utilization efficiency of PMS was optimized by designing the GO-CoFe2O4 particles dosing process. Besides, the cycling stability performance of GO-CoFe2O4 was also examined. The radical quenching tests and ESR detection were conducted to determine the radicals produced by GO-CoFe2O4/PMS. Finally, the underlying enhanced mechanism of GO-CoFe2O4-catalyzed PMS was thoroughly clarified.
The detailed experimental methods were shown in Texts S1-S5 (Supporting information).
SEM and TEM techniques were utilized to witness the morphology of GO, CoFe2O4 and GO-CoFe2O4 (Fig. 1). Figs. 1a and d showed the multilayer GO structure with a slightly wrinkly surface. CoFe2O4 particles with diameters from 100 nm to 200 nm exhibited a rough and irregular polygonal shape and agglomerated appearance (Figs. 1b and e). For GO-CoFe2O4, it showed that the GO morphology was clear, and CoFe2O4 particles were well distributed on GO sheets (Figs. 1c and f). Besides, the support on GO sheets clearly suppressed the aggregation of CoFe2O4, which was attributed to the strong absorption between the multiple functional groups present on the surface of GO and metal sites [21]. It was beneficial to the heterogeneous PMS activation process.
Crystal structures of as-prepared materials were examined by XRD. As seen in Fig. S1 (Supporting information), as a precursor, GO had an intense diffraction peak at around 2θ = 9.5°, regarding the (001) interplanar distance of 0.76 nm, which represented that GO formed a well-ordered layered structure [22]. The pattern of CoFe2O4 in Fig. 2a exhibited peaks at 18.2°, 30.3°, 35.6°, 43.2°, 53.5°, 57.4° and 62.7° which were attributed to (111), (220), (311), (400), (422), (511) and (440) planes, respectively. These were in a well-defined crystal structure of spinel-type CoFe2O4 (JCPDS No. 22–1086, space group Fd 3m (227)). It was evident that the XRD pattern of GO-CoFe2O4 was basically consistent with pure CoFe2O4, without the typical diffraction peak of GO. It validated the successful deposition of CoFe2O4 between the inter-layers of GO. However, the introduction of GO increased the (311) intensity of CoFe2O4 obviously. It was due to the fact that a large number of -OH and -COOH groups on GO combined with H atoms of ferrite to strengthen the spinel structural properties of CoFe2O4 [23]. The peak intensity of GO-CoFe2O4 became low as the GO content increases to 10%. CoFe2O4 crystal growth was constrained by GO layers, and in situ-fabricated CoFe2O4 was covered by redundant GO layers [24].
The wide-scan XPS spectra demonstrated the co-existence of Co, Fe, O, C in 5%GO-CoFe2O4 composite (Fig. S2 in Supporting information). The EDS analysis in Fig. S3 (Supporting information) further confirmed the surface elemental composition of the CoFe2O4 and GO-CoFe2O4 material. The weight percentages of Co, Fe and O in CoFe2O4 were 31.48%, 56.75% and 10.35%, respectively (Table S1 in Supporting information). Another aspect, the weight percentages of Co, Fe, O and C in 5%GO-CoFe2O4 were 30.36%, 49.72%, 11.29% and 5.48%, respectively. The nominal loading weight percentage of GO and the fraction of C showed a strong correlation. Additionally, the less O component indicated the presence of oxygen defects on as-prepared materials.
According to Fig. 2b, FT-IR spectra of GO at about 1730, 1626, 1230 and 1031 cm−1 could ascribe to stretching vibration of C=O and C=C, O—H bending vibrations and C—O stretching vibrations, respectively [25]. Indeed, FT-IR spectra of pure CoFe2O4 displayed a peak at 564 cm−1, which was attributed to the Co-O and Fe-O vibrations [26]. It was worth noting that in the spectra of GO-CoFe2O4, the peaks at 1730 and 1626 cm−1, corresponding to the functional groups of C=O and C=C in GO, blue shifted.
The Raman spectra of GO, CoFe2O4 and 5%GO-CoFe2O4 were depicted in Fig. S4 (Supporting information). At 1352 and 1584 cm−1, respectively, two prominent Raman peaks matched with the D and G bands of GO were seen [27]. The degrees of defects and disorders of carbon materials could be clearly reflected by the intensity ratio of D band and G band. Since D and G's band intensities were fundamentally the same, graphitization of GO was to a lesser extent. It might be brought on the large number of groups that are present on its surface and cause considerable sp3 hybridization. The D and G bands of GO were not found in Raman spectra of the composites because of the low concentration of GO in them. Additionally, CoFe2O4 and 5%GO-CoFe2O4 had obvious characteristic peaks at 323, 498 and 627 cm−1, which were accountable for the stretching vibration of Fe-O on the tetrahedron [28].
The N2 adsorption-desorption isotherms of CoFe2O4 and 5%GO-CoFe2O4 were given in Figs. 2c and d. As observed, both materials possessed the mesoporous structure due to the usual Langmuir-isotherm (type Ⅳ) with a hysteresis loop of H3-type and a centralized pore size distribution within 2–4 nm [29]. The related textural properties were summed up in Table S2 (Supporting information). The specific surface area of CoFe2O4 and 5%GO-CoFe2O4 was 63.38 and 95.84 m2/g, respectively. This result confirmed our hypothesis that the GO sheets would act as a support and inhibit the aggregation of CoFe2O4 (as shown in Figs. 1c and f). Benefiting from the larger surface area, 5%GO-CoFe2O4 could expose more active sites and adequately contact with PMS and contaminations.
The catalytic performances of CoFe2O4 and GO-CoFe2O4 were determined for DBP removal via PMS activation. As presented in Fig. 3a, the individual PMS produced ~6% DBP elimination, indicating its negligible intrinsic oxidizing capacity. The GO/PMS system achieved 19% of DBP removal efficiency within 30 min, indicated that the PMS activation by GO had tiny contribution to DBP removal (Fig. S5 in Supporting information). However, with the addition of CoFe2O4, about 49% of DBP was removed within 30 min. Particularly, a significant increase in the catalytic properties could be effectively accomplished by GO loading, suggesting that the coupling effect between CoFe2O4 and GO greatly improved the activation capacity toward PMS. Meanwhile, the impact of GO content on the catalytic function of GO-CoFe2O4 was examined. The outcomes uncovered a positive correlation between the GO content and the catalytic performance of GO-CoFe2O4, however, the promotion effect was limited. For instance, 90% of DBP removal was obtained over 5%GO-CoFe2O4, while in the 10% GO-CoFe2O4/PMS system, 82% of DBP degradation was attained. The minimal DBP adsorption activity of all catalysts further demonstrated that the removal of DBP was due to degradation rather than adsorption (Figs. S5 and S6 in Supporting information). Additionally, the pseudo-first-order kinetics (ln(C/C) = −kt) could fit the DBP degradation curves well. The rate constant (kDBP) in 5%GO-CoFe2O4/PMS, which was 0.060 min−1 in Fig. 3b, was four times more than that in CoFe2O4/PMS, which was 0.015 min−1. Moreover, 5%GO-CoFe2O4 exhibited better mineralization of DBP than CoFe2O4 (12% vs. 37% of TOC removal) in activating PMS. The results indicated that the heterogeneous structure instead of the physical mixing of GO and CoFe2O4 led to the enhanced catalytic function of GO-CoFe2O4.
Successive experiments were conducted to assess the potential for stability in the 5%GO-CoFe2O4/PMS catalytic system. As figuring out in Fig. 3c, 5%GO-CoFe2O4 continued to exhibit high catalytic activity in the sixth runs. A slight decline in DBP degradation efficiency might cause the unavoidable reduction of catalytic sites during recycling and cleaning. Then, ICP-OES analysis was used to look at the metal leaching capabilities of catalysts. Less than 0.05 and 0.02 mg/L of Co and Fe ions leaked after each cycle, respectively (Fig. 3d). Only around 3% of DBP was lost as a result of leaching, indicating the dominant role of heterogenous catalytic reaction on 5%GO-CoFe2O4. Therefore, it demonstrated excellent stability and recyclability for DBP elimination during PMS activation.
Considering the optimal performance of 5%GO-CoFe2O4 and its great potential for practical use, these variable parameters, such as catalyst dosage, initial DBP concentration, PMS concentration, initial pH and temperature were analyzed. The results were displayed in Fig. 4. In Fig. 4a, when the catalyst dosage was raised from 0.02 g/L to 0.2 g/L, DBP degradation was accelerated from 55% to 93%. The apparent improvement in DBP removal might be explained by a greater dosage of 5%GO-CoFe2O4, which could have created more surface-active sites that assisted in PMS activation and further led to the creation of more reactive ROS. While the DBP degradation minor decreased as the catalyst dosage was increased further, to 0.4 g/L. This finding might primarily be explained by the fact that extra more catalyst particles would self-bond to form aggregates, resulting in a less effective use of active sites on catalyst surfaces [30].
The concentration of contaminants, as an essential component in the treatment of wastewater, had a significant influence on the quantity and duration of PMS that were required. Evidently, raising the initial concentration of DBP slowed down its degradation, as seen in Fig. 4b. As the DBP concentration rose from 1 µmol/L to 4 µmol/L, the DBP elimination in the 5%GO-CoFe2O4/PMS system fell from 97% to 70%. Higher initial concentrations caused less efficient DBP breakdown because more DBP molecules competed for the limited number of reactive species. Additionally, more pollutant molecules would bind to the surface of catalysts that prevented PMS from reacting with the redox-active centers of 5%GO-CoFe2O4. Therefore, an initial DBP concentration of 2 µmol/L was used in our tests to provide appropriate DBP removal and to mimic the trace level in real situations. Furthermore, PMS was an important source of ROSs (i.e., SO4•−, •OH, 1O2) in the oxidation system, also playing a key role in the 5%GO-CoFe2O4/PMS system. DBP removal rate increased from 65% to 98% with PMS concentration ranging from 10 µmol/L to 100 µmol/L, as shown in Fig. 4c. The more PMS participated in the catalytic reaction to form ROSs to enhance the degradation of pollutants.
For the 5%GO-CoFe2O4/PMS system, the effect of initial solution pH on DBP removal was identified. As can be observed from Fig. 4d, DBP elimination significantly improved from 64% to 90% at initial pH values varying from 5.0 to 7.0. The effectiveness of DBP degradation decreased to 75% even though the solution pH climbed further to 9.0. It is widely established that the catalyst surface would become neutral, protonated, or deprotonated, respectively, depending on whether the solution pH was near to, below, or above the pHPZC [31]. The surface of 5%GO-CoFe2O4 became deprotonated and negatively charged at pH > 6.8 (pHPZC), which made HSO5− less likely to bind to the surface of catalyst owing to electrostatic repulsion. In addition, SO4•− would react with OH− to generate •OH with relatively weak oxidative capacity, making the inhibition of DBP removal. Whereas, the decreased removal efficacy of DBP in acidic circumstances was considered to be caused by the creation of an H-bond between H+ and the O—O group of HSO5−, which led to the comparatively high stability of the oxidant [32].
The degradation efficiency of DBP with different amounts of humic acid (HA) or various anions in the 5%GO-CoFe2O4/PMS system was investigated (Fig. S7 in Supporting information). Almost no apparent inhibition on DBP removal efficiency could be observed in the presence of HA with the concentrations in the range of 0–10 mg/L. Besides, the common inorganic species (e.g., Cl−, HCO3−, and NO3− ions) with different concentrations also exhibited a very limited effect on DBP degradation. Herein, 5%GO-CoFe2O4 could be a promising heterogeneous catalyst in PMS activation for the degradation of organic pollutants [33,34].
The PMS decomposition was detected in the 5%GO-CoFe2O4/PMS system, its change trend was consistent with the DBP degradation (Fig. 5a). 91% of PMS was rapidly consumed in the first 3 min, indicating that PMS molecules were rapidly decomposed to generate large amounts of ROSs at this stage. PMS could not be detected at the end of the catalytic reaction. The reaction stoichiometric efficiency was further used to quantify the utilization efficiency of PMS for DBP degradation, it was defined as the ratio of the number of moles of DBP oxidized (Δ[DBP]/[DBP]0) to the number of moles of PMS consumed (Δ[PMS]/[PMS]0) in the presence of 5%GO-CoFe2O4 [35]. As shown in Fig. 5b, PMS utilization increased over reaction time (U0.5 = 0.63 to U30 = 0.87). Besides, with the increase of initial DBP concentration, PMS utilization showed an increasing trend. It was attributed to the fact that the produced amount of ROSs far exceeded the required amount of ROSs for DBP degradation in the initial stage of the reaction, so more DBP molecules could consume the excess ROSs, thereby improving the utilization of PMS. Unfortunately, increasing the initial DBP concentration improved the utilization of PMS, but decreased DBP removal rate. Additionally, we tried to reduce the catalyst dosage to 0.02 g/L, DBP degradation and PMS decomposition were 53.1% and 70%, respectively (Fig. 5c). PMS utilization remained around 0.7 (Fig. 5d). Apparently, although PMS was well utilized when increasing DBP concentration or decreasing catalyst dosage, DBP degradation was not satisfactory.
Considering the practical application, it is necessary to find a reasonable method to improve the PMS utilization efficiency while ensuring DBP degradation. In view of the above, a method, batch delivery of catalyst, was carried out. 0.01 g of catalyst was added to the system at reaction times of 0, 3, and 6 min, and PMS and DBP concentrations were determined. Such a dosing method made PMS always maintain at the stage of rapid decomposition. Therefore, PMS could sustainably generate ROSs to degrade DBP. DBP degradation efficiency reached 80% within 10 min and 90% after 20 min (Fig. 5e). On the other hand, PMS utilization was also maintained at a relatively high value (U10 = 0.87) (Fig. 5f). This dosing method not only saved the amount of catalyst and the reaction time but also achieved the desired degradation efficiency of substance.
DFT calculation was performed to investigate PMS adsorption characteristics and the cleavage of O—O bond on the (311) plane of CoFe2O4 and GO-CoFe2O4, respectively. As shown in Fig. 6, the atomic structures of a PMS molecule adsorbing on the surface of CoFe2O4 (311) (panel a) and GO-CoFe2O4 (100) (panel b) were established, respectively. As summarized in Table S3 (Supporting information), relative to a free PMS molecule without activation, the O—O bond length (lO—O) of PMS was considerably lengthened after binding to catalysts. This implied an enhanced potential to break O—O bonds. The adsorption energy (Eads(HSO5−)) of PMS on (311) plane of GO-CoFe2O4 was −3.14 eV, which was higher than the corresponding value for CoFe2O4 (311) (Eads(HSO5−) = −2.36 eV), respectively. Moreover, the results of the bard charge analysis revealed that the PMS molecules and GO-CoFe2O4 experienced higher charge transfer (Q = 0.16 |e|). The stronger binding affinity and electron transferability indicated that the PMS bound on the GO-CoFe2O4 (311) was more active. It was in line with the conclusions of the experiments that GO-CoFe2O4 possessed better catalytic performance for PMS activation.
In general, the generation efficiency of ROSs during PMS activation was mostly dictated by the catalysts' capacity to transport electrons. In order to highlight the synergy between GO and CoFe2O4 in GO-CoFe2O4 activating PMS, the electrochemical analysis was conducted to measure the redox potential and charge transfer ability in the of 0.5 mol/L Na2SO4 solution mixing with PMS. CV behaviors of CoFe2O4 and GO-CoFe2O4 were explored with a three-electrode device (Fig. 7a). Clear reduction currents were seen with the CoFe2O4 or GO-CoFe2O4 electrodes in the presence of PMS, proving that the reduction process took place on catalyst surfaces in tandem with the breakdown of PMS. Furthermore, GO-CoFe2O4 demonstrated a greater current density and superior reductive ability to CoFe2O4 for coordinating the redox process. It was proposed that GO-CoFe2O4 potentially exhibited a more reliable redox circulation than pure CoFe2O4, which made electron transfer possible in PMS activation.
Besides, to comprehend the charge transfer kinetics at the catalyst/solution interface, EIS plots of CoFe2O4 and GO-CoFe2O4 were recorded (Fig. 7b). Regarding to the EIS Nyquist plots, 5%GO-CoFe2O4 displayed the smallest semicircle diameter, which denoted the lowest charge transfer resistance. Accelerating the charge transfer during the catalytic decomposition of PMS proved advantageous. CoFe2O4 particles were dispersedly supported on GO to achieve the loose structure, and at the same time, the ability of electron transfer about CoFe2O4 particles was promoted by GO [36]. Therefore, the advantages of GO loading to CoFe2O4, which decreased CoFe2O4's intrinsic charge transfer impedance and helped to improve the charge transport between GO-CoFe2O4, PMS, and DBP, were highlighted by the electrochemical results.
To examine the ROSs generated in the 5%GO-CoFe2O4/PMS system, quenching experiments were carried out (Fig. 8a). As a scavenger for SO4•− and •OH, methanol (MeOH) was utilized, with rate constants of 2.5 × 107 and 9.7 × 108 L mol−1 s−1, respectively [37]. tert–Butyl alcohol (TBA), however, was thought to be the unique radical screening agent to selectively quenching •OH (5.6 × 109 L mol−1 s−1) [38]. The addition of 100 mmol/L TBA exhibited an obvious reduction of 42% on DBP degradation and the kDBP value was decreased from 0.060 min−1 to 0.016 min−1 (Fig. 8b). It denoted that •OH existed and help to remove DBP in such an oxidation system. A more noticeable negative impact on the clearance of DBP was seen after overdosing MeOH, the removal rate of DBP fell to 18%. The results had been validated that the results had been validated that the radical oxidation pathway (SO4•− and •OH) played a leading part in the oxidation of DBP due to almost complete suppression.
Besides, we employed superoxide dismutase (SOD, a typical O2•− quenching molecule) to quench the potential O2•− [39]. The negligible inhibition in degradation efficiency ruled out the involvement of O2•− in such a system. Additionally, after adding furfuryl alcohol (FFA, a classic 1O2 scavenger) [40], DBP degradation was incredibly sluggish and 78% of DBP could be broken down. It was hypothesized that 1O2 was generated and played a limited role in 5%GO-CoFe2O4/PMS. Therefore, these findings verified that the degrading mechanism for DBP during the 5%GO-CoFe2O4/PMS process primarily involved SO4•−, •OH and 1O2, with the former two playing a major role.
To explicitly identify the relevant ROSs functioning in the GO-CoFe2O4/PMS catalytic process, in situ ESR studies were also conducted. The lack of distinctive peaks in the DMPO and PMS alone system, as shown in Fig. 8c, proved that no radical could be formed in the absence of catalysts. As anticipated, the CoFe2O4/PMS/DMPO system revealed a set of characteristic peaks indexed to DMPO-OH and DMPO-SO4 adducts, certificating the production of •OH and SO4•− radicals from the broken of peroxide O—O bond in PMS by CoFe2O4 [41]. The three-line peaks of the TEMP-1O2 adducts were simultaneously visible in the CoFe2O4/PMS/TEMP system with equal intensities, demonstrating the formation of 1O2 (Fig. 8d) [42]. Notably, the inclusion of 5%GO-CoFe2O4 greatly increased the relative intensity of the ESR signals, indicating the formation of •OH, SO4•− and 1O2 was enhanced by GO substrate in 5%GO-CoFe2O4/PMS.
Moreover, LSV analysis in Fig. S8a (Supporting information) was used to check the electron transfer pathway. The result demonstrated that the current density upon PMS addition followed by DBP addition showed negligible changes, which eliminated the occurrence of electron transfer pathways in the 5%GO-CoFe2O4/PMS system. The contribution of high-valence metal-oxo species for DBP degradation in the 5%GO-CoFe2O4/PMS system was also excluded by insignificantly adverse effects of DMSO in quenching experiment (Fig. S8b in Supporting information).
To gain knowledge about the catalytic process of 5%GO-CoFe2O4/PMS, the XPS spectra was employed. Significant alterations were seen through comparing the XPS spectra of fresh and used 5%GO-CoFe2O4 samples. It was possible to deconvolute Co 2p into two peaks with binding energies (B.E.) of 780.9 and 778.6 eV, corresponding to CoII and CoIII, respectively [43]. After oxidation, the content of CoII increased from 46% to 52%, while the proportion of CoIII decreased by 6% (Fig. 9a). The peaks at higher B.E. (712.4 eV) in Fig. 9b were attributed to FeIII, while lower B.E. (710.2 eV) were associated to FeII [44]. 54% and 46% of the total Fe was represented by the relative ratios of FeII and FeIII, respectively. After reaction, the relative ratio of FeII dropped slightly, from 54% to 52%, correspondingly, FeIII changed from 46% to 48%. The findings showed that the redox pairs of CoII/CoIII and FeII/FeIII played a role in the catalytic cycle, and aided in the conversion of charges to produce ROSs during PMS activation.
The O 1s spectra (Fig. 9c) was divided into three distinct peaks, which corresponded to H2O at ~532.9 eV, adsorbed oxygen species (Oads) at ~531.1 eV and lattice oxygen species (Olatt) at ~529.7 eV, respectively [45]. The quantity of Olatt was found to have decreased by 7% following the catalytic process, demonstrating that lattice oxygen was used during the catalytic reaction that went along with the redox of metal ions. Accordingly, the percentage of Oads rose from 37% to 50%, showing that certain Oads might change into Olatt by obtaining electrons from the system in conjunction with the oxidation of CoII and FeII. Additionally, the role of dissolved O2 was also be confirmed. As shown in Fig. S9 (Supporting information), the DBP degradation under N2 condition almost equaled the one observed without gas introduction. Furthermore, there was also no visible discrepancy on ESR signal of TEMP-1O2 under air and N2 atmosphere. Therefore, it indicated the dissolved O2 in the water did not contribute significantly to the oxidation of DBP and the generation of 1O2 in this system.
Furthermore, C—C/C=C, C—O, C=O, and O—C=O bonds were identified as the fitting peaks at 284.5, 286.2, 288.2, and 289.5 eV, respectively (Fig. 9d) [46]. After catalysis, it was discovered that the relative ratio of C=O in 5%GO-CoFe2O4 dropped from 14% to 9%. The study came to the conclusion that C=O took part in the catalytic reaction, and that the newly created SO4•− and •OH were also capable of reducing the amount of C=O in 5%GO-CoFe2O4 through the radical oxidation process.
Based upon the aforementioned results, possible PMS activation pathways using GO-CoFe2O4 were postulated and schematically displayed in Fig. 10. DBP degradation was facilitated by both radical and non-radical routes in the GO-CoFe2O4/PMS system. HSO5− and CoII/FeII on the surface of catalyst reacted to form SO4•−, which then oxidized the CoII/FeII to CoIII/FeIII (Eq. 1). Simultaneously, CoIII/FeIII reacted with HSO5− to produce SO5•− (Eq. 2), Additionally, H2O or OH− could partially react with SO4•− to generate •OH in part (Eq. 3). 1O2 was created via the interaction between H2O and SO5•− or the compound of SO5•− (Eqs. 4 and 5). During the GO-CoFe2O4/PMS process, the redox cycles of FeIII/FeII and CoIII/CoII improved the transport of electrons and the production of various ROSs. In the meantime, the plenty of oxygen-containing groups on the surface of GO, such as C=O groups, were electron-rich and hence had a significant potential to coordinate a redox process [47,48]. Additionally, free-flowing electrons from sp2 hybridized carbon network with unpaired electrons promoted the formation of ROSs [49]. Finally, the DBP molecules were quickly broken down by the producing ROSs into minor organic intermediates or even CO2 and H2O (Eq. 6).
In conclusion, a series of GO-CoFe2O4 catalysts with various GO loading levels were prepared. They showed enhanced catalytic activity compared to pure CoFe2O4 in activating PMS for DBP degradation. The excellent removal effectiveness of DBP was achieved under the optimal conditions of 0.1 g/L 5%GO-CoFe2O4, 20 µmol/L PMS, 2 µmol/L of DBP at an initial pH of 7.0, where the attained degradation of DBP was 90%. 5%GO-CoFe2O4 demonstrated a significant increase in catalytic function with the kDBP value of 0.060 min−1, which was almost three times greater than that of CoFe2O4 (kDBP = 0.015 min−1). Moreover, recyclability tests revealed that GO-CoFe2O4 was stable and reusable. The PMS utilization efficiency was significantly improved by the batch dosing of catalysts. Electrons cycling between CoII/CoIII and FeII/FeIII led to the cleavage of PMS to produce SO4•− and •OH and 1O2, which attacked DBP molecules to degrade into tiny molecular species and then further mineralized into CO2 and H2O. The synergistic function between CoFe2O4 and GO led to effective PMS activation and increased SO4•− and •OH generation.
Declaration of competing interest
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The authors declare no conflict of interest.
Acknowledgments
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We appreciate the financial support of the National Natural Science Foundation of China (Nos. 52200010, 52000050), Postdoctoral Science Foundation of China (Nos. 2022M710954, 2020M670913), Open Project of State Key Laboratory of Urban Water Resource and Environment (Harbin Institute of Technology) (Nos. HC202240, 2021TS22).
Supplementary materials
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Supplementary material associated with this article can be found, in the online version, at doi:10.1016/j.cclet.2023.108397.
References
Less
[1]
K. Fent, A.A. Weston, Aquat. Toxicol. 76 (2006) 122–159.
[2]
O. Bajt, G. Mailhot, M. Bolte, Appl. Catal. B: Environ. 33 (2001) 239–248.
[3]
B. Wang, H.X. Wang, W. Zhou, et al., Environ. Sci. Technol. 49 (2015) 1120–1129.
[4]
J. Lee, U.V. Gunten, J.H. Kim, Environ. Sci. Technol. 54 (2020) 3064–3081.
[5]
W.D. Oh, Z. Dong, T.T. Lim, Appl. Catal. B: Environ. 194 (2016) 169–201.
[6]
J.L. Wang, S.Z. Wang, Chem. Eng. J. 334 (2018) 1502–1517.
[7]
P.D. Hu, M.C. Long, Appl. Catal. B: Environ. 181 (2016) 103–117.
[8]
J. Deng, Y. Shao, N. Gao, et al., J. Hazard. Mater. 262 (2013) 836–844.
[9]
K. Zhang, D. Sun, C. Ma, et al., Chemosphere 241 (2020) 125021.
[10]
Y.M. Ren, L.Q. Lin, J. Ma, et al., Appl. Catal. B: Environ. 165 (2015) 572–578.
[11]
L.J. Xu, W. Chu, L. Gan, Chem. Eng. J. 263 (2015) 435–443.
[12]
A.T. Smith, A.M. LaChance, S. Zeng, B. Liu, L. Sun, Nano Mater. Sci. 1 (2019) 31–47.
[13]
J.P. Zhou, H.L. Liu, J. Luo, et al., ACS Appl. Mater. Interfaces 8 (2016) 18140–18149.
[14]
Z.Q. Cai, A.D. Dwivedi, W.N. Lee, et al., Environ. Sci. -Nano 5 (2018) 27–47.
[15]
L. Tang, X. Meng, D. Deng, X. Bao, Adv. Mater. 31 (2019) 1901996.
[16]
W. Choi, I. Lahiri, R. Seelaboyina, Y.S. Kang, Crit. Rev. Solid State 35 (2010) 52–71.
[17]
X. Zhu, Y. Zhu, S. Murali, M.D. Stoller, R.S. Ruoff, ACS Nano 5 (2011) 3333–3338.
[18]
C. Chen, W. Cai, M. Long, et al., ACS Nano 4 (2010) 6425–6432.
[19]
X.R. You, C.Y. Huang, W. Huang, et al., Environ. Sci. : Nano 7 (2020) 554–570.
[20]
J. Deng, L.W. Xiao, S.J. Yuan, et al., Sep. Purif. Technol. 255 (2021) 117685.
[21]
R. Tabit, O. Amadine, Y. Essamlali, et al., RSC Adv. 8 (2018) 1351–1360.
[22]
W.S. Hung, S.M. Chang, R.L.G. Lecaros, et al., Carbon 117 (2017) 112–119.
[23]
N. Meng, R.C.E. Priestley, Y. Zhang, H.T. Wang, X.W. Zhang, J. Membrane Sci. 501 (2016) 169–178.
[24]
D.R. Yang, J. Feng, L.L. Jiang, et al., Adv. Funct. Mater. 25 (2015) 7080–7087.
[25]
N. Li, Z.F. Geng, M.H. Cao, et al., Carbon 54 (2013) 124–132.
[26]
M. Seredych, T.J. Bandosz, J. Mater. Chem. 22 (2012) 23525–23533.
[27]
M. Kim, C. Lee, J. Jang, Adv. Funct. Mater. 24 (2014) 2489–2499.
[28]
K. Ashwini, A.D. Mashkoor, S. Poorva, V. Dinesh, AIP Conf. Proc. 1148 (2014) 1148–1150.
[29]
T. Lin, L. Yu, M. Sun, et al., Chem. Eng. J. 286 (2016) 114–121.
[30]
Y. Zhao, H.Z. An, G.J. Dong, et al., App. Surf. Sci. 505 (2020) 144476.
[31]
Y. Zhao, S. Wang, T. Wei, Y.M. Ren, T.Z. Luan, J. Environ. Chem. Eng. 10 (2022) 107241.
[32]
J. Liu, Z.W. Zhao, P.H. Shao, F.Y. Cui, Chem. Eng. J. 262 (2015) 854–861.
[33]
Z.L. Wu, Z.K. Xiong, R. Liu, et al., J. Hazard. Mater. 427 (2022) 128204.
[34]
R.H. Zhang, M.L. Chen, Z.K. Xiong, Y. Guo, B. Lai, Chin. Chem. Lett. 33 (2022) 948–952.
[35]
Z. Wang, R.T. Bush, L.A. Sullivan, C.C. Chen, J.S. Liu, Environ. Sci. Technol. 48 (2014) 3978–3985.
[36]
S. Wang, M.Y. Zhang, J. Feng, et al., Chem. Eng. J. 430 (2022) 133175.
[37]
Z. Liu, H. Ding, C. Zhao, et al., Water Res. 159 (2019) 111–121.
[38]
Y. Zhao, H.Z. An, J. Feng, Y.M. Ren, J. Ma, Environ. Sci. Technol. 53 (2019) 4500–4510.
[39]
Z.C. Yang, J.S. Qian, A.Q. Yu, B.C. Pan, Proc. Natl. Acad. Sci. U. S. A. 116 (2019) 6659–6664.
[40]
E.T. Yun, J.H. Lee, J. Kim, H.D. Park, J. Lee, Environ. Sci. Technol. 52 (2018) 7032–7042.
[41]
J.J. You, C.Y. Zhang, Z.L. Wu, et al., Chem. Eng. J. 415 (2021) 128890.
[42]
J.E. Yang, Y. Lin, H.H. Peng, et al., Appl. Catal. B: Environ. 268 (2020) 118549.
[43]
L.P. Wu, B. Li, Y. Li, et al., ACS Catal. 11 (2021) 5532–5543.
[44]
A.H. Mady, M.L. Baynosa, D. Tuma, J.J. Shim, Appl. Catal. B: Environ. 244 (2019) 946–956.
[45]
X.B. Hu, B.Z. Liu, Y.H. Deng, et al., Appl. Catal. B: Environ. 107 (2011) 274–283.
[46]
X.T. Li, J. Wang, X.G. Duan, et al., ACS Catal. 11 (2021) 4848–4861.
[47]
C. Liu, S. Liu, L. Liu, et al., Chem. Eng. J. 379 (2020) 122274.
[48]
L.Y. Wu, Z.Y. Li, P.T. Cheng, et al., Water Res. 223 (2022) 119013.
[49]
J. Ye, J.D. Dai, D.Y. Yang, C.X. Li, Y.S. Yan, J. Environ. Chem. Eng. 9 (2021) 106076.
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Year 2023 volume 34 Issue 12
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doi: 10.1016/j.cclet.2023.108397
  • Receive Date：2022-11-10
  • Online Date：2025-11-21
  • Published：2023-12-15
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  • Received：2022-11-10
  • Revised：2023-03-03
  • Accepted：2023-03-28
Affiliations
    State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China
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表12种不同金属材料的力学参数
科
Family		 属数
Number of
genus		 种数
Number of
species		 占总种数比例
Percentage of
total species (%)		 属
Genus		 种数
Number of
species		 占总种数比例
Percentage of total
species (%)
鹅膏菌科Amanitaceae 2 11 5.26 鹅膏菌属 Amanita 10 4.78
小菇科 Mycenaceae 2 12 5.74 丝盖伞属 Inocybe 5 2.39
多孔菌科 Polyporaceae 8 14 6.70 蜡蘑属 Laccaria 5 2.39
红菇科 Russulaceae 3 23 11.00 小皮伞属 Marasmius 6 2.87
小菇属 Mycena 11 5.26
光柄菇属 Pluteus 5 2.39
红菇属 Russula 17 8.13
栓菌属 Trametes 5 2.39
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