Next Article in Journal
Transforming Waste Clamshell into Highly Selective Nanostructured Catalysts for Solvent Free Liquid Phase Oxidation of Benzyl Alcohol
Next Article in Special Issue
Photocatalytic Degradation of Fluoroquinolone Antibiotics in Solution by Au@ZnO-rGO-gC3N4 Composites
Previous Article in Journal
Zeolites and Related Materials as Catalyst Supports for Hydrocarbon Oxidation Reactions
Previous Article in Special Issue
VOCs Photothermo-Catalytic Removal on MnOx-ZrO2 Catalysts
 
 
Search for Articles:
Title / Keyword
Author / Affiliation / Email
Journal
Article Type
 
 
Advanced Search
 
Section
Special Issue
Volume
Issue
Number
Page
 
Journals
Catalysts
Volume 12
Issue 2
10.3390/catal12020152
catalysts-logo
Submit to this Journal Review for this Journal Propose a Special Issue
► Article Menu

Article Menu

share Share announcement Help format_quote Cite question_answer Discuss in SciProfiles thumb_up
...
Endorse textsms
...
Comment
first_page
settings
Order Article Reprints
Font Type:
Arial Georgia Verdana
Font Size:
Aa Aa Aa
Line Spacing:
Column Width:
Background:
Article

Hydrothermal and Co-Precipitated Synthesis of Chalcopyrite for Fenton-like Degradation toward Rhodamine B

by
Po-Yu Wen
1,
Ting-Yu Lai
1,
Tsunghsueh Wu
2,* and
Yang-Wei Lin
1,*
1
Department of Chemistry, National Changhua University of Education, 1 Jin-De Road, Changhua City 50007, Taiwan
2
Department of Chemistry, University of Wisconsin-Platteville, 1 University Plaza, Platteville, WI 53818-3099, USA
*
Authors to whom correspondence should be addressed.
Catalysts 2022, 12(2), 152; https://doi.org/10.3390/catal12020152
Submission received: 31 December 2021 / Revised: 24 January 2022 / Accepted: 25 January 2022 / Published: 26 January 2022
(This article belongs to the Special Issue Heterogeneous Catalysis and Advanced Oxidation Processes (AOP) for Environmental Protection (VOCs Oxidation, Air and Water Purification))
Browse Figures
Versions Notes

Abstract

:
In this study, Chalcopyrite (CuFeS2) was prepared by a hydrothermal and co-precipitation method, being represented as H-CuFeS2 and C-CuFeS2, respectively. The prepared CuFeS2 samples were characterized by scanning electron microscope (SEM), transmission electron microscope (TEM), energy dispersive X-ray spectroscopy mapping (EDS-mapping), powder X-ray diffractometer (XRD), X-ray photoelectron spectrometry (XPS), and Raman microscope. Rhodamine B (RhB, 20 ppm) was used as the target pollutant to evaluate the degradation performance by the prepared CuFeS2 samples. The H-CuFeS2 samples (20 mg) in the presence of Na2S2O8 (4 mM) exhibited excellent degradation efficiency (98.8% within 10 min). Through free radical trapping experiment, the major active species were •SO4− radicals and •OH radicals involved the RhB degradation. Furthermore, •SO4− radicals produced from the prepared samples were evaluated by iodometric titration. In addition, one possible degradation mechanism was proposed. Finally, the prepared H-CuFeS2 samples were used to degrade different dyestuff (rhodamine 6G, methylene blue, and methyl orange) and organic pollutant (bisphenol A) in the different environmental water samples (pond water and seawater) with 10.1% mineral efficiency improvement comparing to traditional Fenton reaction.

Graphical Abstract

1. Introduction

Since the industrial revolution, the development of various industries has made life in human society more convenient, but has also caused many environmental problems. Wastewater, such as cooling water and clean water for equipment, is discharged from various industrial processes. The constituents in any wastewater are diverse and complex consisting of raw materials, intermediate products, by-products, and end products. Charging these compounds directly to the environment can have detrimental consequences. For example, oxygen-containing organic compounds such as aldehydes, ketones, and ethers are reductive, meaning that they are capable of consuming dissolved oxygen in the water to a low-level endangering aquatic organisms. Wastewater can also contain a large amount of nitrogen, phosphorus, and potassium which can promote the growth of algae and triggering eutrophication pollution in water bodies [1]. Released toxic substances from wastewater can bio-accumulate in fish and eventually pass to people who consumed it. Thus, wastewater treatment is an important process to avoid these consequences. Within the treatment options, physical, biological, and chemical methods are mainly used to treat wastewater by removing pollutants in the water and reducing organic pollutants and eutrophic substances in the water [2,3,4,5,6,7,8].
Among many treatment processes, the in-site chemical oxidation method is to inject and mix oxidants into the underground environment aiming to degrade pollutants in groundwater and soil [9,10,11]. Under ideal conditions, this chemical treatment can convert organic pollutants into less toxic molecules, such as carbon dioxide, water, and inorganic salts. The commonly used oxidants are permanganate (MnO4−), Fenton reagent (Fe2+/H2O2), and ozone (O3) [12,13,14,15]. The mechanism of Fenton reagent (Fe2+/H2O2) in reactions has been known to produce •OH radicals, which can cleave C–H bonds of organic compounds, turning them into environmentally benign final products [16,17]. However, this Fenton method has some drawbacks including the specific pH working range and Fe sludge precipitation at the end of the Fenton reaction [18,19]. Another alternative way to generate radicals with a wider pH working range is by using persulfate salts [20,21,22,23,24,25,26]. Persulfate salts can come from two types: peroxymonosulfate (HSO5−) and peroxydisulfate (S2O82−), both of which contain an O–O bond (peroxide group) capable of generating •SO4− radicals and •OH radicals in Fenton-like reaction for degradation of organic compounds [27,28]. Persulfate salts are strong oxidant (E0 = 2.1 V), yet they are very stable for transportation and prolong storage making them very attractive oxidants for underground water treatment [29].
There are a few ways of activating persulfate to generate radicals, such as thermal decomposition, alkaline activation, transition metal ions activation, and heterogeneous catalysis [30]. Among them all, transition metal ions activation is considered the simplest and most benign method with no external energy requirement and recyclability of transition metal ions [31,32,33,34]. Cobalt ions are commonly used in activating persulfate in research, but their hazardous nature makes them unsuitable for water treatment [35,36]. Thus, it is necessary to find an alternative transition metal catalyst that can be used in water treatment.
Recently, Cu/Fe-bearing solids such as chalcopyrite (CuFeS2) have been widely used as catalysts in advanced oxidation processes (AOPs) for wastewater treatment [37,38,39,40,41]. For instance, Dotto et al. demonstrated the ability of their prepared citrate-CuFeS2 materials to degrade 90% of bisphenol A (BPA) in a 15-min Fenton process [42]. Their novel CuFeS2 samples were prepared with a microwave reactor (1400 W, 200 °C, 7 min). Pastrana-Martinez et al. used the mineral of CuFeS2 mined from Jendouba, Tunisia, to catalyze tyrosol degradation (85.0% degradation within 60 min) by using a UV light-assisted Fenton reaction [43]. However, for ground water treatment, this method requires UV light as external energy requirement. Chang et al. proposed that the microwave-assisted synthesis of CuFeS2/Ag3PO4 with enhanced rhodamine B (RhB) degradation (96% degradation within 1 min) under visible light-Fenton process [44]. However, these methods also need light irradiation to improve the degradation performance of CuFeS2.
Herein, we synthesized CuFeS2 samples through hydrothermal and co-precipitated method to realize the advantages in material preparation, stability of materials, and degradation performance in new water treatment option. We expected higher temperature and pressure treatment (hydrothermal process) to make the prepared particles with small size and high special surface area compared to the co-precipitated process, resulting in higher catalytic activity [45,46,47]. In order to prove this, the prepared CuFeS2 samples in the presence of Na2S2O8 were used to evaluate the degradation efficiency of various dyestuff (RhB, rhodamine 6G [R6G], methylene blue [MB], methyl orange [MO], and BPA). The degradation mechanism of CuFeS2 was elucidated and the reactive species were identified. Finally, the practical applications of CuFeS2 samples in the treatment of environmental samples were demonstrated.

2. Results and Discussion

2.1. Characterization of the CuFeS2 Samples

The morphology and composition of the prepared H-CuFeS2 and C-CuFeS2 samples were analyzed through SEM and EDS-mapping (Figure 1). As shown in Figure 1, H-CuFeS2 and C-CuFeS2 samples appear as sphere-like structures, with the average diameter ranging 25–40 nm and 95–125 nm, respectively. The smaller particle size of the H-CuFeS2 samples can be the result of hydrothermal treatment which hindered the particle growth. On the other hand, high concentration of N2H4·H2O was used as reducing agent to prepare C-CuFeS2 samples, resulting in particle agglomeration. In addition, Ostwald ripening may occur during heating procedure. Therefore, small C-CuFeS2 samples dissolved and redeposited onto larger C-CuFeS2 samples. From the results of energy dispersive spectrometer (EDS)-mapping (green color, S elements; blue color, Fe elements; and red color, Cu elements), the presence of Cu, Fe, and S elements in both CuFeS2 samples were confirmed and dispersed well in their crystals.
Figure 2 and Figure 3 showed the TEM images and EDS spectra of the CuFeS2 samples. The diameters of both CuFeS2 samples from TEM images were consistent with the SEM results. We also found both CuFeS2 samples possessed 0.31 nm and 0.23 nm of lattice lines, corresponding to the crystal planes of (112) and (204). The EDS spectra of the prepared CuFeS2 samples confirm the presence of Cu, Fe, and S elements in their crystals, accordingly. The atomic ratios (Cu:Fe:S) for the H-CuFeS2 and C-CuFeS2 samples were determined to be 1.1:1:1.8 and 1.4:1:2.0, respectively. High content of Cu elements in the C-CuFeS2 in the sample is consistent with lower solubility predicted from smaller Ksp value of Cu2S when comparing with Fe2S3 (Ksp of Fe2S3: 3.7 × 10−19, Ksp of Cu2S: 2.0 × 10−47).
XRD was used to investigate the crystal structure of the prepared CuFeS2 samples. The XRD patterns of the prepared CuFeS2 samples are shown in Figure 4A. The diffraction peaks at 29.5°, 49.1°, and 58.6° were identified and assigned to the (112), (204), (312), (204), and (312) faces of the tetragonal chalcopyrite CuFeS2, respectively (PDF 83-0983). Through the Scherrer equation, the average crystal size of H-CuFeS2 and C-CuFeS2 was 20.36 and 11.2 nm, respectively. The Raman spectra of the prepared CuFeS2 samples are shown in Figure 4B. The Raman shifts at 212 cm−1, 276 cm−1, and 379 cm−1 correspond to the S element, Cu(I)-S, and Fe(III)-S stretching vibration, respectively.
As another quality assurance method, XPS analysis of the prepared CuFeS2 samples (Figure 5 and Figure 6) revealed that it contains three elements: Cu, Fe, and S [48,49]. High-resolution XPS revealed Cu2p, Fe2p, and S2p in the H-CuFeS2 samples as shown in Figure 5B–D, respectively. In Figure 5B, the peaks at 931.9 and 951.7 eV correspond to Cu+ 2p3/2 and Cu+ 2p1/2, respectively, whereas those at 933.2 and 953.0 eV correspond to Cu2+ 2p3/2 and Cu2+ 2p1/2, respectively. The peaks at 711.7 and 724.9 eV correspond to Fe2+ 2p3/2 and Fe2+ 2p1/2, respectively, whereas those at 715.2 and 734.3 eV correspond to Fe3+ 2p3/2 and Fe3+ 2p1/2, respectively (Figure 5C). The peaks at 162.5 and 167.8 eV correspond to S2− 2p and S6+ 2p, respectively (Figure 5D). For C-CuFeS2 samples, the peaks at 931.9 and 951.6 eV correspond to Cu+ 2p3/2 and Cu+ 2p1/2, respectively, whereas those at 934.1 and 952.7 eV correspond to Cu2+ 2p3/2 and Cu2+ 2p1/2, respectively (Figure 6B). The peaks at 711.4 and 724.8 eV correspond to Fe2+ 2p3/2 and Fe2+ 2p1/2, respectively, whereas those at 714.6 and 734.2 eV correspond to Fe3+ 2p3/2 and Fe3+ 2p1/2, respectively (Figure 6C). The peaks at 162.5 and 168.9 eV correspond to S2− 2p and S6+ 2p, respectively (Figure 6D).
According to its peak area, the percentage of different oxidation states of each element in the prepared CuFeS2 samples can be estimated. In H-CuFeS2 samples, elemental compositions were found 82.3% Cu+ and 17.6% Cu2+ from Cu analysis, 66.9% Fe2+ and 33.1% Fe 3+ from Fe analysis, and 74.2% S2− and 25.7% S6+ from sulfur analysis. In C-CuFeS2 samples, elemental composition was found to be 90.6% Cu+ vs. 9.3% Cu2+ for Cu, 60.8% Fe2+ vs. 39.2% Fe 3+ for Fe, and 62.6% S2− vs. 37.3%. S6+ for S.

2.2. Degradation Performance of the CuFeS2 Samples

The degradation activity of the prepared CuFeS2 samples was evaluated with RhB (20 ppm) first. According to our previous experience, the degradation efficiency decreased with an increasing dye concentration. This is because the excessive coverage of dye on the active surface of catalysts leads to a decrease in the catalytic activity. Thus, 20 ppm RhB was selected for the experiment. The variations in the RhB concentration (C/C0), where C0 is the initial RhB concentration, and C is the RhB concentration at time t, with the reaction time for the prepared CuFeS2 samples in the presence of H2O2 (Fenton reaction) and Na2S2O8 (Fenton-like reaction), were found in Figure 7. Prior to the addition of the oxidant, each catalyst (0.20 g) was introduced to the 20 ppm RhB solution for 30 min in the dark (indicated as “−30 min” in Figure 7) to reach equilibrium. The RhB concentration for H-CuFeS2 samples after this equilibration time is lower than that of C-CuFeS2 samples, reflecting RhB adsorption on H-CuFeS2 samples. This is because smaller size of the H-CuFeS2 samples had higher specific surface area than C-CuFeS2 samples. Through the Fenton reaction, the degradation efficiency within 30 min was 32.3% and 26.4% for the H-CuFeS2 and C-CuFeS2 samples, respectively (black and blue curve). This suggests that the degradation performance of H-CuFeS2 is better than that of C-CuFeS2, attributable to adsorption ability of high specific surface area for the H-CuFeS2 samples. The results of RhB degradation through a Fenton-like reaction by the H-CuFeS2 and C-CuFeS2 samples were shown in the red and pink curve. The degradation efficiency within 30 min reaction time follows this order: H-CuFeS2 (93.7%) > C-CuFeS2 (66.3%), indicating H-CuFeS2 having higher catalytic activity to produce •SO4− radicals. Furthermore, we found that degradation performance of •SO4− radicals is higher than that of •OH radicals for both CuFeS2 samples. This is because of the different lifetimes of radicals (•SO4− radicals: 4 s, •OH radicals: 1 μs). Thus, the degradation system of H-CuFeS2 through a Fenton-like reaction was selected for the further study.
To maximize the degradation performance of H-CuFeS2, the effect from various concentrations of Na2S2O8 was studied. As shown in Figure 8, the degradation efficiency increased with increasing Na2S2O8 concentration. Due to low solubility of Na2S2O8, we selected 4.0 mM of Na2S2O8 as the optimum required concentration of Na2S2O8. Dye adsorption on H-CuFeS2 was observed in the absence of Na2S2O8 (black cure in Figure 9). Although direct degradation of RhB by Na2S2O8 without H-CuFeS2 was noticed from the experiment due to the high oxidizing strength of Na2S2O8 (red curve in Figure 9), its rate of degradation cannot compete with H-CuFeS2 samples in the presence of Na2S2O8, which achieved an impressive 98.8% within 10 min (blue cure in Figure 9). In addition, we also analyzed the degradation performances of Cu2S and FeS2 nanoparticles to investigate which element is important for a Fenton-like reaction. As shown in Figure 10, the RhB degradation efficiency within 15 min reaches 64.1% and 89.0% for Cu2S and FeS nanoparticles, respectively. These results suggested that the FeS2 nanoparticles catalyze Na2S2O8 to produce •SO4− radicals better than Cu2S nanoparticles, indicating Fe component is important than Cu component for the Fenton-like reaction.

2.3. Degradation Mechanism of H-CuFeS2

As a key mechanistic study, the active species involved in the degradation reaction were identified systematically using the free radical trapping experiments (Figure 11A). Methanol and NaN3 were used as •OH and •SO4− scavengers, respectively. Comparing to methanol, NaN3 inhibit RhB degradation more, indicating that •SO4− radicals are the major species involved in the Fenton-like degradation (blue curve in Figure 11A). According to the results of the scavenger test and XPS experiment, we propose a possible degradation mechanism. First, Fe2+/Cu+ ions on the CuFeS2 surface catalyzed S2O82− to produce •SO4− radicals (Equations (1) and (2)). Due to high oxidation activity of •SO4− radicals (E0 = 2.5–3.1 V), they were utilized to degrade dyes and to oxidize Fe2+/Cu+ ions (Equations (3)–(5)). Then, •OH radicals also produced from the oxidation reaction between •SO4− radicals and H2O/OH− to degrade the dyes (Equations (6)–(8)). Thus, after adding methanol to the reaction mixture, RhB degradation in CuFeS2 samples was slightly decreased, indicating that production of •OH radicals are considered as the indirect active species in the CuFeS2 catalyzed RhB degradation (red curve in Figure 11A).
Fe2+ + S2O82− → Fe3+ + •SO4− + SO42−
Cu+ + S2O82− → Cu2+ + •SO4− + SO42−
•SO4− + RhB → CO2 + H2O
•SO4− + Fe2+ → Fe3+ + SO42−
•SO4− + Cu+ → Cu2+ + SO42−
•SO4− + H2O → SO42− + •OH + H+
•SO4− + OH− → SO42− + •OH
•OH + RhB → CO2 + H2O
•SO4− radical production in the Fenton-like reaction was further studied using the spectrophotometric method [50]. According to Equations (9) and (10), I3− solution (light yellow) was found from chemical reaction between S2O82− and KI. The absorbance spectra of the S2O82−/KI solution in the absence and presence of the prepared CuFeS2 samples were evaluated. Figure 11B shows that an absorbance peak was observed at 358 nm for each sample and that the maximum absorbance was observed in the absence of the prepared CuFeS2 samples (blue curve in Figure 11B). This suggests that S2O82− produced the highest amount of I2 compared to others, thereby leading to more chemical reactions with KI to generate I3−. Due to a high specific surface area and high content of Fe2+ ions, H-CuFeS2 effectively catalyzed S2O82− to produce •SO4− radicals, as a result of a few I2 production. Thus, the absorbance intensity at 358 nm of H-CuFeS2/S2O82−/KI mixing solution (black curve in Figure 11B) was lower than that of C-CuFeS2/S2O82−/KI mixing solution (red curve in Figure 11B).
S2O82− + 2I− → 2SO42− + I2
I2 + KI → I3− + K+
On the basis of the results described above, the degradation scheme of the H-CuFeS2 samples in the Fenton-like reaction was proposed (Scheme 1). •SO4− radicals and •OH radicals were produced from the Fenton-like reaction between S2O82− and Fe2+/Cu+ ions on the H-CuFeS2 surface to degrade RhB (Equations (1)–(8)). Then, Fe2+/Cu+ ions were regenerated through a series reduction of S2− anions (Equations (11)–(13)). Moreover, it is also possible to produce Fe2+ ions by reduction reaction between Cu+ and Fe3+ ions (Equation (14)).
S2− + Fe3+/Cu2+ → Fe2+/Cu+ + S22−
S22− + Fe3+/Cu2+ → Fe2+/Cu+ + Sn2−
Sn2− + Fe3+/Cu2+ → Fe2+/Cu+ + SO42−
Cu+ + Fe3+ → Fe2+ + Cu2+

2.4. Stability and Practical Applications of H-CuFeS2

The stability of the catalyst is an essential parameter for the development of practical water treatment applications. To investigate the stability of H-CuFeS2, results of pH effect, copper ions effect, and cyclic RhB degradation tests were evaluated as shown in Figure 12, Figure 13 and Figure 14. Figure 12 showed the study of pH effect. RhB degradation by H-CuFeS2 at pH 4.0 maintained a similar degradation efficiency at pH 7.0 (98.48% at pH 4.0 and 98.49% at pH 7.0, respectively), whereas that at pH 10.0 resulted in a considerable loss of efficiency (72.13% at pH 10.0). This is because most •SO4− radicals were converted to •OH radicals at alkaline condition (Equations (6)–(8)). Thus, •OH radicals are the major active radicals involved in dye degradation at alkaline condition. In addition, inactive porphyrin ferryl complexes (FeO2+) are formed as Fe2+ ions in the alkaline solution. As a result, a weakened degradation result at pH 10.0 was found (Figure 12).
In the study of copper ion effect as shown in Figure 13, RhB degradation efficiencies by H-CuFeS2 in the presence of Cu+ ioins were 88.64% at pH 4.0, 91.21% at pH 7.0, and 87.42% at pH 10.0, whereas those in the presence of Cu2+ ions were 93.96% at pH 4.0, 94.21% at pH 7.0, and 91.19% at pH 10.0. Comparing to that at pH 10.0 in the absence of copper ions, an obvious improvement was found. This is because •SO4− radicals are produced in the presence of Cu+ ions (Equation (2)). In addition, Fe2+/Cu+ ions were regenerated through reduction between S2− anions and Fe3+/Cu2+ ions (Equations (11)–(13)). As a result, an improve degradation at pH 10.0 was found.
For recyling-used study, Figure 14A showed RhB degradation by H-CuFeS2 exhibited a considerable loss of efficiency (from 98.48% to 72.46% after three cycles). Furthermore, the corresponding XRD, Raman, and SEM results (Figure 14B–D) suggest a decrease in the phase structure of the H-CuFeS2 samples after the repeated reactions, indicating the destruction of the H-CufeS2 sample crystalization. In addition, EDS spectrum found that the atomic ratio (Cu:Fe:S) for the third used H-CuFeS2 samples was determined to be 1:1:1.9. The morphology of the third used samples still retained sphere-like structures, with the average diameter ranging 20–35 nm. Further research to improve recycling-used ability by other heterojunction, such as those doped by Ag@Ag3PO4 nanoparticles, is now underway in our laboratory.
To assess the practical applications of H-CuFeS2 as a new water treatment option, various dyes (R6G, MB, and MO) and colorless organic compound (BPA) were tested (Figure 15A). H-CuFeS2 exhibited excellent degradation efficiency toward R6G, MB, MO, and BPA, with 96.84%, 93.86%, 81.89%, and 75.24% degradation achieved within 10 min, respectively. In addition, the mineralization performance of H-CuFeS2 comparing to a traditional Fenton reaction (Fe2+/H2O2) was evaluated. From the TOC analysis (Figure 15B), mineralization efficiency for the Fe2+/H2O2 and H-CuFeS2/S2O82− system was 70.0% and 80.1%, respectively, representing 10.1% improvement of RhB degradation. Finally, the prepared H-CuFeS2 samples were used to degrade RhB in the environmental water samples (pond water and seawater). H-CuFeS2 exhibited adequate mineralization efficiency through the Fenton-like reaction for RhB degradation. A notable difference in the mineralization efficiency for RhB was observed for the seawater samples (47.9% efficiency within 10 min) compared with pond water samples (63.8% efficiency within 10 min), probably because of the effect of higher concentration of anions or radical scavengers in the seawater sample that reduced the degradation activity of H-CuFeS2. Nevertheless, the studies on the environmental water samples strongly support the benefits of this newly developed H-CuFeS2-based Fenton-like water treatment option.

3. Materials and Methods

3.1. Preparation of CuFeS2

All chemicals were purchased from Sigma Aldrich (St. Louis, MO, USA) and were of analytical grade and used without further purification. In this study, hydrothermal (H) and co-precipitated method (C) were used to prepare CuFeS2 samples, representing as H-CuFeS2 and C-CuFeS2, respectively. For hydrothermal procedure, 0.989 g of CuCl, and 2.703 g of FeCl3·6H2O were added to 57 mL of deionized water, with stirring for 10 min. Then, 8 mL of Na2S ·9H2O (0.02 mol) was added dropwisely into the above green mixture. After stirring for 30 min, the black mixture was transferred into a Teflon-lined stainless-steel autoclave. The autoclave was sealed and heated in an electric oven at 200 °C for 10 h. After the autoclave naturally cooled to room temperature, the precipitates were centrifuged (5000 rpm, 15 min) and washed three times with ethanol and deionized water, and then dried in vacuum at 60 °C overnight. In addition, Cu2S and FeS2 nanoparticles were prepared following similar method without adding FeCl3·6H2O and CuCl precursor, respectively.
For the co-precipitated method, 4.95 mg of CuCl, and 0.0135 g of FeCl3·6H2O were added to 20 mL of deionized water, with stirring at 70 °C for 10 min. Then, 1 mL of NH4OH (30%) and 1 mL of N2H4·H2O (64–65%) were added dropwise into the above mixture with stirring at 70 °C for 3 h. After that, 0.024 g of Na2S·9H2O was added into the above brown mixture with stirring at 70 °C for 3 h. Finally, the black precipitates were centrifuged (5000 rpm, 15 min) and washed three times with ethanol and deionized water, and then dried in vacuum at 60 °C overnight.

3.2. Characterization of CuFeS2

The morphological and compositional characteristics of all as-prepared samples were observed with scanning electron microscopy (SEM) on a HITACHI S-4300 (Hitachi, Tokyo, Japan) and transmission electron microscopy (TEM) on a 1200EX II (JEOL, Tokyo, Japan) equipped with a QUANTAX Annular XFlash QUAD FQ5060 (Bruker Nano, Berlin, Germany). The crystallographic texture of the samples was measured by powder X-ray diffraction (XRD) on SMART APEX II (Bruker AXS, Billerica, MA, USA) using Cu Kα radiation (λ = 1.5406 Å). Raman spectra were collected at room temperature using a confocal micro-Raman system (Thermo Scientific Inc., New York, NY, USA). A 532 nm laser line was used as the photoexcitation source with a laser power of 2 mW focused on the sample for 10 s. The binding energy of elements was determined through X-ray photoelectron spectroscopy (XPS) on a VG ESCA210 (VG Scientific, West Sussex, UK).

3.3. Degradation Procedure

RhB degradation was used to assess the degradation activity of the prepared samples. For the Fenton-like reaction, 20 mg of the prepared catalyst samples was added into the RhB solution (20 ppm, 50 mL), and the solution was stirred in the dark for 30 min. At 10 min before adding Na2S2O8, the absorbance at its characteristic absorption peak of 550 nm was measured to check the adsorption ability of the prepared samples. Subsequently, 100 μL of Na2S2O8 (2 M) was added to dye solution. After a given time interval, 1 mL of suspension was sampled with a plastic pipette and this aliquot was quenched immediately by adding 10 μL NaN3 (1 M) and filtered by a 0.22-μm syringe filter organic membrane to remove catalyst particles. The concentration of RhB was measured using a Synergy H1 hybrid multimode microplate reader (BioTek Instruments, Winooski, VT, USA) at its characteristic absorption peak of 550 nm. Similar processes were performed for other catalysts (Cu2S and FeS2), dyestuffs (R6G, MB, and MO), and organic pollutant (BPA). After the experiment, TOC concentration was determined on an Elementar Acquray TOC analyzer (Elementar Analysensysteme GmbH, Langenselbold, Germany) to evaluate the extent of mineralization.

3.4. Free Radical Trapping Experiment

To investigate the active species generated during RhB degradation over H-CuFeS2, the trapping experiment was conducted using NaN3 and methanol (each 0.1 M) as the capturing agent for •SO4− radicals and •OH radicals, respectively. The implemented trapping experimental procedure was identical to the steps mentioned in the degradation section with an additional step of adding the capturing agent at each run.

4. Conclusions

The prepared H-CuFeS2 samples showed higher RhB degradation efficiency through the Fenton-like reaction than the prepared C-CuFeS2, FeS2, Cu2S nanoparticles, and previously reported samples (Table 1). This high enhancement in the degradation efficiency (98.8% RhB degradation within 10 min) was attributed to the prepared H-CuFeS2 samples possessed smaller size and higher surface area. Based on the results of scavenger test and radicals’ quantitation experiments, H-CuFeS2 catalyzed Na2S2O8 to produce •SO4− radicals and •OH radicals for the organics degradation. As we know, the three limiting factors to address prior to industrial application were viable methods of catalyst preparation, the catalyst durability and universality under operating conditions. The prepared H-CuFeS2 samples possessed several attractive features. First, the prepared H-CuFeS2 samples in the presence of Na2S2O8 had 98.8% RhB degradation performance within 10 min. In addition, various organics (R6G, MB, MO, and BPA) with 75.24–96.84% degradation efficiency could be achieved. However, the repeated use of H-CuFeS2 showed performance deterioration due to the change in the crystal phase of used H-CuFeS2. Further research on the high recycling-used ability of other heterojunction CuFeS2 composites, such as those doped by Ag@Ag3PO4 nanoparticles, is now underway in our laboratory. Finally, the prepared H-CuFeS2 samples were used to degrade RhB with 10.1% mineralization improvement comparing to traditional Fenton reaction (Fe2+/H2O2). It is also easy to recover H-CuFeS2 catalyst comparing to Fe2+ ions. In addition, H-CuFeS2 catalyst deposited on a cellulose-based substrate is ongoing in our lab. The difficult separation and recycle of powder catalyst may result in high cost and secondary pollution, therefore, the powder form of catalyst greatly limited the commercial industrial application. More importantly, H-CuFeS2 deposited on cellulose is very suitable for the dynamic-flow water treatment system. We will propose a new adsorption-degradation strategy for the pollutant removal in industrial level application in the future.
In summary, this study discovered the hydrothermal synthesis of CuFeS2 samples and successfully demonstrated the application of the Fenton-like reaction in the environmental water samples. The current findings can be used to the application of AOPs in wastewater treatment in the future.

Author Contributions

Conceptualization, P.-Y.W. and Y.-W.L.; methodology, Y.-W.L.; software, Y.-W.L.; validation, P.-Y.W., T.-Y.L. and T.W.; formal analysis, P.-Y.W., T.-Y.L. and Y.-W.L.; investigation, P.-Y.W.; resources, Y.-W.L.; data curation, P.-Y.W. and T.-Y.L.; writing—original draft preparation, Y.-W.L.; writing—review and editing, T.W. and Y.-W.L.; visualization, Y.-W.L.; supervision, Y.-W.L.; project administration, Y.-W.L.; funding acquisition, Y.-W.L. All authors have read and agreed to the published version of the manuscript.

Funding

This study was supported by the Ministry of Science and Technology of Taiwan under contract (MOST 110-2113-M-018-001).

Conflicts of Interest

The authors declare no conflict of interest.

References

  1. Su, Y. Revisiting carbon, nitrogen, and phosphorus metabolisms in microalgae for wastewater treatment. Sci. Total Environ. 2021, 762, 144590. [Google Scholar] [CrossRef] [PubMed]
  2. Saeed, M.; Khan, I.; Adeel, M.; Akram, N.; Muneer, M. Synthesis of CoO-ZnO photocatalyst for enhanced visible-light assisted photodegradation of methylene blue. New J. Chem. 2022. [Google Scholar] [CrossRef]
  3. Nipa, S.T.; Akter, R.; Raihan, A.; Rasul, S.B.; Som, U.; Ahmed, S.; Alam, J.; Khan, M.R.; Enzo, S.; Rahman, W. State-of-the-art biosynthesis of tin oxide nanoparticles by chemical precipitation method towards photocatalytic application. Environ. Sci. Pollut. Res. 2022. [Google Scholar] [CrossRef] [PubMed]
  4. Varsha, M.; Kumar, P.S.; Rathi, B.S. A review on recent trends in the removal of emerging contaminants from aquatic environment using low-cost adsorbents. Chemosphere 2022, 287, 132270. [Google Scholar] [CrossRef]
  5. Bilińska, L.; Gmurek, M. Novel trends in AOPs for textile wastewater treatment. Enhanced dye by-products removal by catalytic and synergistic actions. Water Resour. Ind. 2021, 26, 100160. [Google Scholar] [CrossRef]
  6. Qasem, N.A.; Mohammed, R.H.; Lawal, D.U. Removal of heavy metal ions from wastewater: A comprehensive and critical review. NPJ Clean Water 2021, 4, 36. [Google Scholar] [CrossRef]
  7. Kamran, U.; Bhatti, H.N.; Noreen, S.; Tahir, M.A.; Park, S.-J. Chemically modified sugarcane bagasse-based biocomposites for efficient removal of acid red 1 dye: Kinetics, isotherms, thermodynamics, and desorption studies. Chemosphere 2022, 291, 132796. [Google Scholar] [CrossRef]
  8. Kamran, U.; Bhatti, H.N.; Iqbal, M.; Jamil, S.; Zahid, M. Biogenic synthesis, characterization and investigation of photocatalytic and antimicrobial activity of manganese nanoparticles synthesized from Cinnamomum verum bark extract. J. Mol. Struct. 2019, 1179, 532–539. [Google Scholar] [CrossRef]
  9. Li, J.; He, C.; Cao, X.; Sui, H.; Li, X.; He, L. Low temperature thermal desorption-chemical oxidation hybrid process for the remediation of organic contaminated model soil: A case study. J. Contam. Hydrol. 2021, 243, 103908. [Google Scholar] [CrossRef]
  10. Huang, R.; Zhu, Y.; Curnan, M.T.; Zhang, Y.; Han, J.W.; Chen, Y.; Huang, S.; Lin, Z. Tuning reaction pathways of peroxymonosulfate-based advanced oxidation process via defect engineering. Cell Rep. Phys. Sci. 2021, 2, 100550. [Google Scholar] [CrossRef]
  11. Sun, Y.; Li, D.; Zhou, S.; Shah, K.J.; Xiao, X. Research Progress of Advanced Oxidation Water Treatment Technology. Adv. Waterwater Treat. II 2021, 102, 1–47. [Google Scholar]
  12. Walton, J.; Labine, P.; Reidies, A. The chemistry of permanganate in degradative oxidations. In Chemical Oxidation; Eckenfelder, W.W., Bowers, A.R., Roth, J.A., Eds.; Technomic Publishing Co., Inc.: Lancaster, Basel, 1991; Volume 1, pp. 205–219. [Google Scholar]
  13. Luo, H.; Zeng, Y.; He, D.; Pan, X. Application of iron-based materials in heterogeneous advanced oxidation processes for wastewater treatment: A review. Chem. Eng. J. 2021, 407, 127191. [Google Scholar] [CrossRef]
  14. Sgroi, M.; Anumol, T.; Vagliasindi, F.G.; Snyder, S.A.; Roccaro, P. Comparison of the new Cl2/O3/UV process with different ozone-and UV-based AOPs for wastewater treatment at pilot scale: Removal of pharmaceuticals and changes in fluorescing organic matter. Sci. Total Environ. 2021, 765, 142720. [Google Scholar] [CrossRef] [PubMed]
  15. Deniere, E.; Alagappan, R.P.; Van Langenhove, H.; Van Hulle, S.; Demeestere, K. The ozone-activated peroxymonosulfate process (O3/PMS) for removal of trace organic contaminants in natural and wastewater: Effect of the (in) organic matrix composition. Chem. Eng. J. 2022, 430, 133000. [Google Scholar] [CrossRef]
  16. Ganiyu, S.O.; Zhou, M.; Martinez-Huitle, C.A. Heterogeneous electro-Fenton and photoelectro-Fenton processes: A critical review of fundamental principles and application for water/wastewater treatment. Appl. Catal. B Environ. 2018, 235, 103–129. [Google Scholar] [CrossRef]
  17. Labiadh, L.; Ammar, S.; Kamali, A.R. Oxidation/mineralization of AO7 by electro-Fenton process using chalcopyrite as the heterogeneous source of iron and copper catalysts with enhanced degradation activity and reusability. J. Electroanal. Chem. 2019, 853, 113532. [Google Scholar] [CrossRef]
  18. Ribeiro, J.P.; Nunes, M.I. Recent trends and developments in Fenton processes for industrial wastewater treatment–A critical review. Environ. Res. 2021, 197, 110957. [Google Scholar] [CrossRef]
  19. Mahtab, M.S.; Farooqi, I.H.; Khursheed, A. Sustainable approaches to the Fenton process for wastewater treatment: A review. Mater. Today 2021, 47, 1480–1484. [Google Scholar] [CrossRef]
  20. Liang, S.; Ziyu, Z.; Fulong, W.; Maojuan, B.; Xiaoyan, D.; Lingyun, W. Activation of persulfate by mesoporous silica spheres-doping CuO for bisphenol A removal. Environ. Res. 2022, 205, 112529. [Google Scholar] [CrossRef]
  21. Liang, S.; Ziyu, Z.; Han, J.; Xiaoyan, D. Facile synthesis of magnetic mesoporous silica spheres for efficient removal of methylene blue via catalytic persulfate activation. Sep. Purif. Technol. 2021, 256, 117801. [Google Scholar] [CrossRef]
  22. Kiejza, D.; Kotowska, U.; Polińska, W.; Karpińska, J. Peracids-New oxidants in advanced oxidation processes: The Use of peracetic acid, peroxymonosulfate, and persulfate salts in the removal of organic micropollutants of emerging concern—A review. Sci. Total Environ. 2021, 790, 148195. [Google Scholar] [CrossRef] [PubMed]
  23. Zhang, B.-T.; Wang, Q.; Zhang, Y.; Teng, Y.; Fan, M. Degradation of ibuprofen in the carbon dots/Fe3O4@carbon sphere pomegranate-like composites activated persulfate system. Sep. Purif. Technol. 2020, 242, 116820. [Google Scholar] [CrossRef]
  24. Feng, Y.; Zhong, J.; Zhang, L.; Fan, Y.; Yang, Z.; Shih, K.; Li, H.; Wu, D.; Yan, B. Activation of peroxymonosulfate by Fe0@Fe3O4 core-shell nanowires for sulfate radical generation: Electron transfer and transformation products. Sep. Purif. Technol. 2020, 247, 116942. [Google Scholar] [CrossRef]
  25. Tan, C.; Xu, Q.; Sheng, T.; Cui, X.; Wu, Z.; Gao, H.; Li, H. Reactive oxygen species generation in FeOCl nanosheets activated peroxymonosulfate system: Radicals and non-radical pathways. J. Hazard. Mater. 2020, 398, 123084. [Google Scholar] [CrossRef]
  26. Sun, L.; Hu, D.; Zhang, Z.; Deng, X. Oxidative degradation of methylene blue via PDS-based advanced oxidation process using natural pyrite. Int. J. Environ. Res. Public Health 2019, 16, 4773. [Google Scholar] [CrossRef] [Green Version]
  27. Zhu, Y.; Liu, Y.; Li, P.; Zhang, Y.; Wang, G.; Zhang, Y. A comparative study of peroxydisulfate and peroxymonosulfate activation by a transition metal–H2O2 system. Environ. Sci. Pollut. Res. 2021, 28, 47342–47353. [Google Scholar] [CrossRef]
  28. Ghanbari, F.; Khatebasreh, M.; Mahdavianpour, M.; Mashayekh-Salehi, A.; Aghayani, E.; Lin, K.-Y.A.; Noredinvand, B.K. Evaluation of peroxymonosulfate/O3/UV process on a real polluted water with landfill leachate: Feasibility and comparative study. Korean J. Chem. Eng. 2021, 38, 1416–1424. [Google Scholar] [CrossRef]
  29. Dung, N.T.; Thao, V.D.; Huy, N.N. Decomposition of glyphosate in water by peroxymonosulfate activated with CuCoFe-LDH material. Vietnam J. Chem. 2021, 59, 813–822. [Google Scholar]
  30. Wang, W.; Chen, M.; Wang, D.; Yan, M.; Liu, Z. Different activation methods in sulfate radical-based oxidation for organic pollutants degradation: Catalytic mechanism and toxicity assessment of degradation intermediates. Sci. Total Environ. 2021, 772, 145522. [Google Scholar] [CrossRef]
  31. Xu, X.; Tang, D.; Cai, J.; Xi, B.; Zhang, Y.; Pi, L.; Mao, X. Heterogeneous activation of peroxymonocarbonate by chalcopyrite (CuFeS2) for efficient degradation of 2, 4-dichlorophenol in simulated groundwater. Appl. Catal. B Environ. 2019, 251, 273–282. [Google Scholar] [CrossRef]
  32. Karim, A.V.; Jiao, Y.; Zhou, M.; Nidheesh, P. Iron-based persulfate activation process for environmental decontamination in water and soil. Chemosphere 2021, 265, 129057. [Google Scholar] [CrossRef] [PubMed]
  33. Hou, K.; Pi, Z.; Yao, F.; Wu, B.; He, L.; Li, X.; Wang, D.; Dong, H.; Yang, Q. A critical review on the mechanisms of persulfate activation by iron-based materials: Clarifying some ambiguity and controversies. Chem. Eng. J. 2021, 407, 127078. [Google Scholar] [CrossRef]
  34. Zheng, X.; Niu, X.; Zhang, D.; Lv, M.; Ye, X.; Ma, J.; Lin, Z.; Fu, M. Metal-based catalysts for persulfate and peroxymonosulfate activation in heterogeneous ways: A review. Chem. Eng. J. 2022, 429, 132323. [Google Scholar] [CrossRef]
  35. Li, B.; Wang, Y.-F.; Zhang, L.; Xu, H.-Y. Enhancement strategies for efficient activation of persulfate by heterogeneous cobalt-containing catalysts: A review. Chemosphere 2021, 291, 132954. [Google Scholar] [CrossRef]
  36. Fayyaz, A.; Saravanakumar, K.; Talukdar, K.; Kim, Y.; Yoon, Y.; Park, C.M. Catalytic oxidation of naproxen in cobalt spinel ferrite decorated Ti3C2Tx MXene activated persulfate system: Mechanisms and pathways. Chem. Eng. J. 2021, 407, 127842. [Google Scholar] [CrossRef]
  37. Nie, W.; Mao, Q.; Ding, Y.; Hu, Y.; Tang, H. Highly efficient catalysis of chalcopyrite with surface bonded ferrous species for activation of peroxymonosulfate toward degradation of bisphenol A: A mechanism study. J. Hazard. Mater. 2019, 364, 59–68. [Google Scholar] [CrossRef]
  38. Huang, X.; Zhu, T.; Duan, W.; Liang, S.; Li, G.; Xiao, W. Comparative studies on catalytic mechanisms for natural chalcopyrite-induced Fenton oxidation: Effect of chalcopyrite type. J. Hazard. Mater. 2020, 381, 120998. [Google Scholar] [CrossRef]
  39. Li, Y.; Dong, H.; Li, L.; Tang, L.; Tian, R.; Li, R.; Chen, J.; Xie, Q.; Jin, Z.; Xiao, J. Recent advances in wastewater treatment through transition metal sulfides-based advanced oxidation processes. Water Res. 2021, 192, 116850. [Google Scholar] [CrossRef]
  40. Xia, Q.; Zhang, D.; Yao, Z.; Jiang, Z. Investigation of Cu heteroatoms and Cu clusters in Fe-Cu alloy and their special effect mechanisms on the Fenton-like catalytic activity and reusability. Appl. Catal. B Environ. 2021, 299, 120662. [Google Scholar] [CrossRef]
  41. Xia, Q.; Zhang, D.; Yao, Z.; Jiang, Z. Revealing the enhancing mechanisms of Fe–Cu bimetallic catalysts for the Fenton-like degradation of phenol. Chemosphere 2022, 289, 133195. [Google Scholar] [CrossRef]
  42. Da Silveira Salla, J.; da Boit Martinello, K.; Dotto, G.L.; García-Díaz, E.; Javed, H.; Alvarez, P.J.; Foletto, E.L. Synthesis of citrate–modified CuFeS2 catalyst with significant effect on the photo–Fenton degradation efficiency of bisphenol a under visible light and near–neutral pH. Colloid Surf. A Physicochem. Eng. Asp. 2020, 595, 124679. [Google Scholar] [CrossRef]
  43. Ltaïef, A.H.; Pastrana-Martínez, L.M.; Ammar, S.; Gadri, A.; Faria, J.L.; Silva, A.M. Mined pyrite and chalcopyrite as catalysts for spontaneous acidic pH adjustment in Fenton and LED photo-Fenton-like processes. J. Chem. Technol. Biotechnol. 2018, 93, 1137–1146. [Google Scholar] [CrossRef]
  44. Chang, S.-A.; Wen, P.-Y.; Wu, T.; Lin, Y.-W. Microwave-Assisted Synthesis of Chalcopyrite/Silver Phosphate Composites with Enhanced Degradation of Rhodamine B under Photo-Fenton Process. Nanomaterials 2020, 10, 2300. [Google Scholar] [CrossRef] [PubMed]
  45. Kamran, U.; Park, S.-J. Hybrid biochar supported transition metal doped MnO2 composites: Efficient contenders for lithium adsorption and recovery from aqueous solutions. Desalination 2022, 522, 115387. [Google Scholar] [CrossRef]
  46. Kamran, U.; Park, S.-J. Acetic acid-mediated cellulose-based carbons: Influence of activation conditions on textural features and carbon dioxide uptakes. J. Colloid Interface Sci. 2021, 594, 745–758. [Google Scholar] [CrossRef] [PubMed]
  47. Kamran, U.; Park, S.-J. Tuning ratios of KOH and NaOH on acetic acid-mediated chitosan-based porous carbons for improving their textural features and CO2 uptakes. J. CO2 Util. 2020, 40, 101212. [Google Scholar] [CrossRef]
  48. Ghahremaninezhad, A.; Dixon, D.; Asselin, E. Electrochemical and XPS analysis of chalcopyrite (CuFeS2) dissolution in sulfuric acid solution. Electrochim. Acta 2013, 87, 97–112. [Google Scholar] [CrossRef]
  49. Jiang, L.; Luo, Z.; Li, Y.; Wang, W.; Li, J.; Li, J.; Ao, Y.; He, J.; Sharma, V.K.; Wang, J. Morphology-and phase-controlled synthesis of visible-light-activated S-doped TiO2 with tunable S4+/S6+ ratio. Chem. Eng. J. 2020, 402, 125549. [Google Scholar] [CrossRef]
  50. Liang, C.; Huang, C.-F.; Mohanty, N.; Kurakalva, R.M. A rapid spectrophotometric determination of persulfate anion in ISCO. Chemosphere 2008, 73, 1540–1543. [Google Scholar] [CrossRef]
  51. Jia, J.; Liu, D.; Wang, S.; Li, H.; Ni, J.; Li, X.; Tian, J.; Wang, Q. Visible-light-induced activation of peroxymonosulfate by TiO2 nano-tubes arrays for enhanced degradation of bisphenol A. Sep. Purif. Technol. 2020, 253, 117510. [Google Scholar] [CrossRef]
Catalysts 12 00152 g001 550
Figure 1. SEM images and EDS-mapping of (A) H-CuFeS2 and (B) C-CuFeS2 samples.
Figure 1. SEM images and EDS-mapping of (A) H-CuFeS2 and (B) C-CuFeS2 samples.
Catalysts 12 00152 g001
Catalysts 12 00152 g002 550
Figure 2. TEM images and EDS spectra of H-CuFeS2 samples.
Figure 2. TEM images and EDS spectra of H-CuFeS2 samples.
Catalysts 12 00152 g002
Catalysts 12 00152 g003 550
Figure 3. TEM images and EDS spectra of C-CuFeS2 samples.
Figure 3. TEM images and EDS spectra of C-CuFeS2 samples.
Catalysts 12 00152 g003
Catalysts 12 00152 g004 550
Figure 4. (A) XRD and (B) Raman spectra of H-CuFeS2 (black), and C-CuFeS2 (red) samples.
Figure 4. (A) XRD and (B) Raman spectra of H-CuFeS2 (black), and C-CuFeS2 (red) samples.
Catalysts 12 00152 g004
Catalysts 12 00152 g005 550
Figure 5. XPS spectra of H-CuFeS2 samples: (A) full scan, (B) Cu2p, (C) Fe2p, and (D) S2p.
Figure 5. XPS spectra of H-CuFeS2 samples: (A) full scan, (B) Cu2p, (C) Fe2p, and (D) S2p.
Catalysts 12 00152 g005
Catalysts 12 00152 g006 550
Figure 6. XPS spectra of C-CuFeS2 samples: (A) full scan, (B) Cu2p, (C) Fe2p, and (D) S2p.
Figure 6. XPS spectra of C-CuFeS2 samples: (A) full scan, (B) Cu2p, (C) Fe2p, and (D) S2p.
Catalysts 12 00152 g006
Catalysts 12 00152 g007 550
Figure 7. Fenton and Fenton-like reactions for RhB degradation at different conditions: H-CuFeS2 in the presence of H2O2 (black), H-CuFeS2 in the presence of Na2S2O8 (red), C-CuFeS2 in the presence of H2O2 (blue), and C-CuFeS2 in the presence of Na2S2O8 (pink).
Figure 7. Fenton and Fenton-like reactions for RhB degradation at different conditions: H-CuFeS2 in the presence of H2O2 (black), H-CuFeS2 in the presence of Na2S2O8 (red), C-CuFeS2 in the presence of H2O2 (blue), and C-CuFeS2 in the presence of Na2S2O8 (pink).
Catalysts 12 00152 g007
Catalysts 12 00152 g008 550
Figure 8. Fenton-like reaction for RhB degradation by H-CuFeS2 samples at different concentration of Na2S2O8.
Figure 8. Fenton-like reaction for RhB degradation by H-CuFeS2 samples at different concentration of Na2S2O8.
Catalysts 12 00152 g008
Catalysts 12 00152 g009 550
Figure 9. Fenton-like reaction for RhB degradation under different conditions: H-CuFeS2 samples only (black), Na2S2O8 only (red), and H-CuFeS2 in the presence of Na2S2O8 (blue). Top image: photographs of the RhB solution under the Fenton reaction at different reaction time.
Figure 9. Fenton-like reaction for RhB degradation under different conditions: H-CuFeS2 samples only (black), Na2S2O8 only (red), and H-CuFeS2 in the presence of Na2S2O8 (blue). Top image: photographs of the RhB solution under the Fenton reaction at different reaction time.
Catalysts 12 00152 g009
Catalysts 12 00152 g010 550
Figure 10. Fenton-like reaction for RhB degradation in the presence of Na2S2O8 by using different catalysts: Cu2S (black), FeS2 (red), and H-CuFeS2 (blue).
Figure 10. Fenton-like reaction for RhB degradation in the presence of Na2S2O8 by using different catalysts: Cu2S (black), FeS2 (red), and H-CuFeS2 (blue).
Catalysts 12 00152 g010
Catalysts 12 00152 g011 550
Figure 11. (A) Free radical trapping experiment and (B) absorbance spectra at different condition.
Figure 11. (A) Free radical trapping experiment and (B) absorbance spectra at different condition.
Catalysts 12 00152 g011
Catalysts 12 00152 sch001 550
Scheme 1. Possible scheme of Fenton-like reaction for the H-CuFeS2 samples.
Scheme 1. Possible scheme of Fenton-like reaction for the H-CuFeS2 samples.
Catalysts 12 00152 sch001
Catalysts 12 00152 g012 550
Figure 12. Fenton-like reaction for RhB degradation by the H-CuFeS2 samples at different pH value system.
Figure 12. Fenton-like reaction for RhB degradation by the H-CuFeS2 samples at different pH value system.
Catalysts 12 00152 g012
Catalysts 12 00152 g013 550
Figure 13. RhB degradation efficiency by the H-CuFeS2 samples at different pH value system in the presence of copper ions.
Figure 13. RhB degradation efficiency by the H-CuFeS2 samples at different pH value system in the presence of copper ions.
Catalysts 12 00152 g013
Catalysts 12 00152 g014 550
Figure 14. (A) Fenton-like reaction for RhB degradation by the H-CuFeS2 samples for the recycling -used test, (B) XRD, (C) Raman spectra, and (D) SEM image of the 3rd used samples.
Figure 14. (A) Fenton-like reaction for RhB degradation by the H-CuFeS2 samples for the recycling -used test, (B) XRD, (C) Raman spectra, and (D) SEM image of the 3rd used samples.
Catalysts 12 00152 g014
Catalysts 12 00152 g015 550
Figure 15. Fenton-like reaction of (A) different dyestuff by the H-CuFeS2 samples, (B) TOC analysis of different degradation systems by using Fe(II) and the H-CuFeS2 samples in the different environmental water samples.
Figure 15. Fenton-like reaction of (A) different dyestuff by the H-CuFeS2 samples, (B) TOC analysis of different degradation systems by using Fe(II) and the H-CuFeS2 samples in the different environmental water samples.
Catalysts 12 00152 g015
Table
Table 1. Comparison of degradation performance using the (photo-) Fenton-like reaction.
Table 1. Comparison of degradation performance using the (photo-) Fenton-like reaction.
SamplesPreparationDegradation PerformanceTargetRef.
CuO/MSSHydrothermal method90% degradation (0.15 g catalyst/50 ppm BPA) within 45 minBPA[20]
MMSSSurface etching method90% degradation (0.1 g catalyst/50 ppm MB) within 60 minMB[21]
Natural pyriteMined from Anhui, China90% degradation (0.1 g catalyst/100 ppm MB) within 120 minMB[26]
CDs/Fe3O4@CSSolvothermal method96% degradation (0.3 g catalyst/50 μM Ibuprofen (IBP)) within 2 h (350-W Xe lamp)IBP[23]
TiO2 nanotubes arraysAnodization94.6% degradation (1 ppm BPA) within 30 min (300-W Xe lamp)BPA[51]
Fe0@Fe3O4 nanowiresReduction method100% degradation (2.5 mg catalyst/0.5 ppm Atrazine (ATZ)) within 6 minATZ[24]
FeOCl nanosheetsPyrolysis method86.5% degradation (0.05 g catalyst/10 μM Phenacetin (PCNT)) within 30 minPCNT[25]
CuFeS2Hydrothermal method98.8% degradation (0.02 g catalyst/20 ppm RhB) within 10 minRhB, R6G, MB, MO, BPAThis study
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.

Share and Cite

MDPI and ACS Style

Wen, P.-Y.; Lai, T.-Y.; Wu, T.; Lin, Y.-W. Hydrothermal and Co-Precipitated Synthesis of Chalcopyrite for Fenton-like Degradation toward Rhodamine B. Catalysts 2022, 12, 152. https://doi.org/10.3390/catal12020152

AMA Style

Wen P-Y, Lai T-Y, Wu T, Lin Y-W. Hydrothermal and Co-Precipitated Synthesis of Chalcopyrite for Fenton-like Degradation toward Rhodamine B. Catalysts. 2022; 12(2):152. https://doi.org/10.3390/catal12020152

Chicago/Turabian Style

Wen, Po-Yu, Ting-Yu Lai, Tsunghsueh Wu, and Yang-Wei Lin. 2022. "Hydrothermal and Co-Precipitated Synthesis of Chalcopyrite for Fenton-like Degradation toward Rhodamine B" Catalysts 12, no. 2: 152. https://doi.org/10.3390/catal12020152

Note that from the first issue of 2016, this journal uses article numbers instead of page numbers. See further details here.

Article Metrics

Back to TopTop