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Through a simple grinding procedure, MIL-53Fe@PDI, a novel Z-scheme photocatalytic material, was synthesized. MIL-53Fe showed minimal photocatalytic activity under visible light for the degradation of doxycycline hydrochloride. Upon composite formation with PDI (perylene-3,4,9,10-tetracarboxylic diimide), the photocatalytic performance of MIL-53Fe significantly improved. The improvement was credited to the effective separation of carriers enabled by the Z-scheme heterojunction of MIL-53Fe@PDI, which hinders the recombination of electrons and holes generated by light. MIL-53Fe@PDI was utilized to enhance the breakdown effectiveness of doxycycline hydrochloride by triggering peroxymonosulphate in the presence of visible light. Thorough examinations were carried out to analyse how the amount of peroxymonosulphate, the concentration of doxycycline hydrochloride, various inorganic anions, and natural organic matter impact the activation of peroxymonosulphate for the degradation of doxycycline hydrochloride. Experiments involving radical quenching and analysis using electron paramagnetic resonance verified the activation mechanism of MIL-53Fe@PDI with peroxymonosulphate, indicating the significant involvement of sulphate and superoxide radicals in the degradation of doxycycline hydrochloride. Predictions of potential susceptible locations and routes of doxycycline hydrochloride were made using density functional theory calculations utilizing the Fukui function and UPLC-MS. Toxicity Estimation Software Tool indicated a gradual reduction in toxicity during the degradation of doxycycline hydrochloride. This study presents an effective and environmentally friendly approach for treating antibiotic wastewater. [ABSTRACT FROM AUTHOR]

The rapid, efficient, and thorough degradation of Bisphenol A (BPA) is challenging. In this study, we prepared an effective peroxymonosulphate (PMS) activation catalyst derived from sawdust containing calcium carbonate. The Co and Cu co-doped sawdust biochar (CoO/CuO@CBC) catalyst could activate PMS quickly, and the degradation rate of BPA reached 99.3% in 5 min, while the rate constant was approximately 30 times higher than in the CBC/PMS and CoCuOx/PMS systems. Moreover, the interaction between CoO, CuO, and CBC endows the CoO/CuO@CBC catalyst with excellent catalytic performance under different conditions, such as initial pH, temperature, water matrix, inorganic anions, and humic acid, which maintained fast PMS activation via the cyclic transformation of Cu and Co for BPA degradation. The results demonstrated that both the radical (•O2− and •SO4−) and non-radical (1O2) pathways participate in the degradation of BPA in the CoO/CuO@CBC/PMS system. The efficient and stable degradation over a wide range of pH, temperature, and aqueous matrices indicates the potential application of the CoO/CuO@CBC catalyst. [ABSTRACT FROM AUTHOR]

In this study, each cobalt tetra-aminophthalocyanine (CoTAPc) molecule was immobilised with four isonicotinic acid (INA) molecules by amide bonding, a novel and highly efficient catalyst pyridine-bridged cobalt tetra-aminophthalocyanine (CoTAPc-TINA) was synthesised. The introduction of INA molecules promoted CoTAPc to expose more active sites, and increased the electron cloud density of cobalt ions promoting O–O bond homolysis of PMS to generate more active species, which significantly enhanced catalytic activity. With the pharmaceutical of carbamazepine (CBZ) as model pollutant, 0.1 g/L CoTAPc-TINA in dark in the presence of 0.4 mM PMS, 98.8% CBZ was removed within 10 min. However, under the same conditions the removed of CBZ was only 58.9% by CoTAPc/PMS system. Radical capture experiments combined electron paramagnetic resonance technology demonstrate that hydroxyl radicals, sulphate radicals, superoxide radicals and singlet oxygen are the main active species in the CoTAPc-TINA/PMS system. As the reaction proceeded, all aromatic intermediates were transformed to small molecular acids by these active species. This investigation provided a new insight for application of metal phthalocyanine in wastewater treatment. [ABSTRACT FROM AUTHOR]

The sulphate radical based advanced oxidation processes (AOPs) are highly in demand these days, owing to their numerous advantages. Herein, the Fe-Mn bimetallic oxide particle was used to activate peroxymonosulphate (PMS) for Rhodamine B (RhB) degradation. Three bimetallic catalysts were synthesized via the chemical precipitation method with different concentrations of metals; Fe-Mn (1:1), Fe-Mn (1:2) and Fe-Mn (2:1). The best performance was shown by Fe-Mn (2:1) system at optimized conditions; 96% of RhB was removed at optimized conditions. Scavenging experiments displayed the clear dominance of hydroxyl radical in pH 3, while sulphate radical was present in a large amount at pH 7 and 10. The monometallic Fe and Mn oxides were also synthesized to confirm the synergistic effect that was present in the bimetallic oxide system. The application of optimized condition in real textile wastewater was conducted, which revealed the system works efficiently at high concentrations of PMS and catalyst dosage. [ABSTRACT FROM AUTHOR]

In recent times, the application of biochar (BC) as an upcoming catalyst for the elimination of recalcitrant pollutants has been widely explored. Here, an iron loaded bamboo biochar activated peroxymonosulphate (PMS) process was tested for removing Congo red (CR) dye from water medium. The catalyst was synthesized using a green synthesis method using neem extracts and characterized using SEM, FTIR, and XRD. The effects of various operating parameters, including solution pH, catalyst dosage, and pollutant dosage, on dye degradation efficiency were examined. The results showed that at the optimized conditions of 300 mg L−1 PMS concentration, 200 mg L−1 catalyst dosage, and pH 6, about 89.7% of CR dye (initial concentration 10 ppm) was removed at 60 min of operation. Scavenging experiments revealed the significant contribution of O 2 •−, •OH, and 1O 2 for dye degradation, with a major contribution of O 2 •−. The activation of PMS was mainly done by biochar rather than iron (loaded on biochar). The catalyst was highly active even after four cycles. [Display omitted] • Application of green synthesized iron-loaded biochar as a PMS activator. • The superior performance of biochar in the activation by PMS. • O 2.•− is the primary oxidant responsible for dye degradation • •OH and 1O 2 were also produced in the catalyst-activated PMS process • SO 4.•− has less contribution to dye degradation [ABSTRACT FROM AUTHOR]

The development of novel visible powered nano-heterojunctions with multi-pronged capabilities for environmental and catalytic applications has been gaining importance for persistent pollutant degradation & clean energy production. A magnetically recoverable biochar supported ternary g-C 3 N 4 /Bi 2 O 2 CO 3 /CoFe 2 O 4 heterojunction (BCBF) was fabricated which shows a high visible photoactivity. The heterojunction was used for degradation of pesticide paraquat under visible radiation (Xe lamp), natural sunlight, photo-ozonation, peroxymonosulphate, and coupled conditions. A high degradation of 99.3% was achieved under visible radiation in 90 min and 92.1% under solar light in 120 min. Biochar supported ternary junction performs manifold faster than Bi 2 O 2 CO 3 /CoFe 2 O 4 , g-C 3 N 4 /CoFe 2 O 4 , g-C 3 N 4 /CoFe 2 O 4 , Bi 2 O 2 CO 3 (BOC), CoFe 2 O 4 (CF) and g-C 3 N 4 (CN). The effect of operational parameters as effect of pH, H 2 O 2 , anions, ozone and peroxymonosulphate (PMS) was also studied. In BCBF + PMS + O 3  + Vis protocol a spectacular complete degradation was observed in less than 30 min. Ternary band structure efficiently reduces the charge recombination rate and promotes spectral activity which was confirmed by photoluminescence, photocurrent response and EIS analysis. By LC-MS, scavenging experiments and ESR studies a possible mechanism was also proposed. Cyto-toxicity studies of degraded products on human peripheral blood cells revealed almost 99% cell viability affirming the complete mineralization. The junction was also used for reduction of 4-nitrophenol into 4-aminophenol with complete conversion in less than 5 min with rate constant 13.05 × 10 −3  s −1 . In addition the ternary junction shows a high visible powered conversion of CO 2 producing CH 4 (∼119 µmol g −1 ), CO (∼131 µmol g −1 ) and O 2 (∼242 µmol g −1 ) with a high rate constant of 13.05 × 10 −3  s −1 . [ABSTRACT FROM AUTHOR]

With a view to engender an advanced oxidation protocol, in the present investigation a very efficient and outperforming catalytic system has been developed which employs peroxymonosulphate (PMS) as oxidant and surface metal functionalized core-shell nanostructures (with ferrite as core coated with shell of dopamine and surface functionalized with transition metal nanoparticles) as catalysts. The present protocol bids fast and facile degradation of organic pollutants without the aid of any promoting radiations. Every component of the developed core-shell nanostructures (M@Dop@CoFe; M = Cr, Mn, Fe, Co, Ni, Cu and Zn) has been found to contribute synergistically in the overall oxidative-degradation process. Co@Dop@CoFe presented the best results for the oxidative-degradation of nitrophenols (NP) taken as model pollutants with rate constant values of 8.13 × 10 −1  min −1 , 3.56 × 10 −1  min −1 and 17.15 × 10 −1  min −1 for 2-NP, 3-NP and 4-NP respectively. The synthesized core-shell nanocatalysts have been established to be leach-proof and recyclable to a very good extent. [ABSTRACT FROM AUTHOR]

Freshwater disinfection using photolytic and catalytic activation of peroxymonosulphate (PMS) through PMS/UV-A LED and PMS/M n+ /UV-A LED [M n+ = Fe 2+ or Co 2+ ] processes was evaluated through the inactivation of three different bacteria: Escherichia coli (Gram-negative), Bacillus mycoides (sporulated Gram-positive), Staphylococcus aureus (non-sporulated Gram-positive), and the fungus Candida albicans . Photolytic and catalytic activation of PMS were effective in the total inactivation of the bacteria using 0.1 mM of PMS and M n+ at neutral pH (6.5), with E. coli reaching the highest and the fastest inactivation yield, followed by S. aureus and B. mycoides . With B. mycoides , the oxidative stress generated through the complexity of PMS/M n+ /UV-A LED combined treatments triggered the formation of endospores. The treatment processes were also effective in the total inactivation of C. albicans , although, due to the ultrastructure, biochemistry and physiology of this yeast, higher dosages of reagents (5 mM of PMS and 2.5 mM of M n+ ) were required. The rate of microbial inactivation markedly increased through catalytic activation of PMS particularly during the first 60 s of treatment. Co 2+ was more effective than Fe 2+ to catalyse PMS decomposition to sulphate radicals for the inactivation of S. aureus and C. albicans . The inactivation of the four microorganisms was well represented by the Hom model. The Biphasic and the Double Weibull models, which are based on the existence of two microbial sub-populations exhibiting different resistance to the treatments, also fitted the experimental results of photolytic activation of PMS. [ABSTRACT FROM AUTHOR]

The treatment of winery effluents through sulphate radical-based advanced oxidation processes (SR-AOPs) driven by solar radiation is reported in this study. Photolytic and catalytic activations of peroxymonosulphate (PMS) and persulphate (KPS and SPS) at different pH values (4.5 and 7) were studied in the degradation of organic matter. Portugal is one of the largest wine producers in Europe. The wine making activities generate huge volume of effluents characterized by a variable volume and organic load, being their seasonal nature one of the most important drawbacks. Recently, SR-AOPs are gradually attracting attention as in situ chemical oxidation technologies, instead of hydroxyl radical AOPs (HR-AOPs). The studied concentrations are suitable to obtain notable values of organic matter degradation, with TOC removal around 50%. In general terms, no notable differences were observed between treatments at pH values 4.5 and 7. Photolytic activation of SPS with solar radiation treatments obtained the highest efficiency (28 and 40% of TOC removal with 1 and 50 mM, respectively, at pH 4.5) in comparison to KPS and PMS. The addition of a transition metal as catalyst, such as Fe(II) or Co(II), increased considerably the TOC removal efficiency higher than 50%, but not in all cases. For instance, the combination KPS or PMS with Co(II) at pH 4.5 did not allow to obtain better results than photolytic activation of these persulphate salts. In summary, the use of SR-AOPs could be a serious alternative as tertiary treatment for winery wastewaters. [ABSTRACT FROM AUTHOR]

The inactivation of four different microorganisms, Escherichia coli , Bacillus mycoides , Staphylococcus aureus and Candida albicans, inoculated in simulated (SWW) and real winery wastewaters (RWW), was assessed by the first time using free sulphate and hydroxyl radicals from photolytic (UV-A LED radiation; 370 nm) and metal [Fe(II) or Co(II)] activation of peroxymonosulphate (PMS). The experimental conditions tested were [PMS] = 0.1 mM and [Fe(II) or Co(II)] = 0.1 mM and pH 5.0 for the inactivation of microorganisms in SWW. However, due to the complexity of the water matrix, not unexpectedly, a fivefold concentration of reagents was required to inactivate the same organisms in RWW. In addition, compared to the bacteria, the fungus C. albicans presented a higher oxidative stress resistance to the treatments, and different experimental conditions were necessary to inactivate these cells. After 90 min, the photolytic activation of PMS through UV-A LED radiation achieved complete inactivation of E. coli , followed by S. aureus (≈4 log) and B. mycoides (≈3 log). Total inactivation of C. albicans was also achieved, but with higher dosages of PMS (10 mM). The metal activation of PMS through the use of a transition metal [Fe(II) or Co(II)] accelerated the inactivation rate, particularly in the first minutes of exposure time. These treatments reached between 1 and 3 log inactivation of microorganisms in the first minute of the experiment. In addition, the use of Co(II) as promoter in the activation of PMS, was more effective in the inactivation of S. aureus and C. albicans than activation with Fe(II). Since linear mathematical models do not adjust satisfactorily to inactivation results in all cases, different mathematical models were tested to fit the experimental inactivation data. In general, the Hom model correctly fits the inactivation results of the four microorganisms in all applied treatments. However, other models such as Biphasic and Double Weibull fit acceptably as well. [ABSTRACT FROM AUTHOR]

In this study, the effectiveness of the HSO 5 − /M n + /UV process on the treatment of winery wastewater (WW) was investigated. The optimal operating conditions were determined: [HSO 5 − ] = 2.5 mM; [M 2 (SO 4 ) n ] = 1.0 mM; pH = 6.5 and reaction temperature = 323 K. Under the given conditions, 51%, 42% and 35% of COD removal was achieved using respectively Fe(II), Co(II) and Cu(II) as catalysts. Different UV sources were tested with the previously selected optimal conditions in order to increase the treatment efficiency. The highest COD removal (82%) was achieved using a UV-A LEDs system (70 W/m 2 ). These conditions were also promising for the treatment of WW with COD concentrations of 5000 mg O 2 /L, reaching 79% and 64% of COD and TOC removal, respectively, after 180 min of treatment. At 323 K, the most effective treatment was obtained when Co(II) was used as catalyst (79% and 64% of COD and TOC removal), while at ambient temperature (293 K) the highest COD (65%) and TOC (52%) removals were obtained with Fe(II) catalyst. Moreover, it was demonstrated that the use of HSO 5 − /M n + in several consecutive doses was more efficient than adding the reagents as a single dose at the beginning of the reaction. A comparison between the performance of the HSO 5 − /Fe(II)/UV-A LED process and the conventional photo-Fenton demonstrated important advantages associated with the HSO 5 − /Fe(II)/UV-A LED process, including the absence of the costly pH adjustment and of the hydroxide ferric sludge which characterise the photo-Fenton treatment process. The HSO 5 − /M n + /UV-A LED process demonstrates a high COD and TOC removal efficiency, and it can be considered a promising technology for application in real scale agro-food wastewater treatment plants. [ABSTRACT FROM AUTHOR]

Chemical treatment processes have mostly been considered as an efficient way for biosolid minimization. The improvement of sludge dewatering was more a welcome side-effect of these sequential processes. In this study, heat-activated sodium peroxydisulphate (PDS) and potassium peroxymonosulphate (MPS) were applied in order to disintegrate waste activated sludge (WAS). PDS and MPS treatment of WAS results in the polymer transfer of organic matter from the solid phase to the liquid phase. Our research work was done for chemical disintegration of WAS by PDS and MPS in doses of 0.2%, 0.4%, 0.6%, 0.8% and 1% (169.5, 339.0, 508.5, 678.0 and 847.5 mg ) activated at temperatures of 60°C and 90°C for 30 min. The application of these methods causes the soluble chemical oxygen demand value to increase in the supernatant. In addition, there was a positive influence on the sludge volume index which decreased for the highest doses of PDS of over 63% and 77% and MPS of over 78% and 82% through heat activation at temperatures of 60°C and 90°C, respectively. Furthermore, MPS was more successful in the floc particle destruction, therefore it caused a higher sludge settlement acceleration (sedimentation/compaction speed) than PDS. The experimental results demonstrated that the application of heat-activated PDS and MPS may become a novel effective way of processing sewage sludge. [ABSTRACT FROM PUBLISHER]

Determination of persulphate is important in persulphate based advanced oxidation process (AOP). Potassium iodide (KI) based iodometry has been the conventional method for determination of persulphate. Recently, determination of persulphate by decolorization of organic pollutants via cobalt ion activated persulphate was reported. Here, we have studied the oxidative coloration of N,N-diethyl-p-phenylenediamine (DPD) by persulphates such as peroxydisulphate (PDS) and peroxymonosulphate (PMS). At room temperature, oxidation of DPD by these persulphates generated pink colored solution that showed absorption maximum at 510 and 551 nm. Importantly, the absorption at 510 and 551 nm increased linearly on increasing the concentration of persulphate, and linear calibration graphs were obtained with PDS and PMS concentrations in the range between 10 μM and 100 μM for quantitative analysis of persulphate. Determination of persulphates by the oxidative coloration of DPD was in good agreement with those determined by KI based conventional iodometric titration. Importantly, after analysis, the pink colored oxidized DPD waste solution was rapidly degraded by heat (80 °C) activated persulphate. Additionally, DPD, oxidized pink colored DPD waste solution left over after analysis, showed no bactericidal effect towards Escherichia coli , a common bacterium. Moreover, the colorless solution obtained after the degradation of pink oxidized DPD wastes by thermal activation of persulphate also showed no bactericidal effect towards E. coli . Degradation of DPD by persulphate activation, as well as the absence of bactericidal effect by DPD and its wastes, supports that the proposed DPD method for persulphate determination is environment friendly. Thus, the study highlights DPD as a potential colorimetric reagent for the spectrophotometric determination of both PDS and PMS that are commonly used for persulphate based AOP. [ABSTRACT FROM AUTHOR]

This work presents about the study of inorganic oxidants assisted sonocatalytic degradation of Resazurin (RZ) dye in the presence of β-SnWO 4 nanoparticles. The catalysts were synthesized via a surfactant free sonochemical method. Physical properties of the as-prepared β-SnWO 4 nanoparticles were analyzed by XRD and FE-SEM. The dispersion property and particle size were analyzed by Zeta potential and Particle size analyzer. The degradation of RZ was analyzed in the presence and absence of common oxidants such as PMS ( peroxymonosulfate) and H 2 O 2 (hydrogen peroxide). The result shows that the RZ was first mineralized to Resorufin and it was degraded to simple molecule in the presence of β-SnWO 4 . 75% of degradation efficiency was achieved in presence of β-SnWO 4 , while in addition of H 2 O 2 and PMS, the efficiency was increased up to 93% and 85% respectively. Our results will pave a new opening in degradation of poisonous dye using inorganic common oxidants. [ABSTRACT FROM AUTHOR]

Abstract: Some industrial wastewaters contain both hexavalent chromium and surfactants. In this work, their removal from aqueous solution by zero-valent iron (ZVI) and peroxymonosulphate (PMS) was studied using Brij 35 as a representative non-ionic surfactant. The performance of the ZVI/PMS system in the simultaneous removal of both pollutants was compared to that achieved with control solutions containing either Cr(VI) or Brij 35 separately. Reactions were carried out over 24h at initial pH=2.3 with variable initial amounts of Cr(VI) and Brij 35. The results showed that surfactant removal was enhanced in the system also containing Cr(VI). Surfactant degradation followed zero-order kinetics and produced formic acid as the main by-product, together with hydroxylated aldehydes, formates and alcohols that were identified by LC/MS. The presence of surfactant similarly enhanced Cr(VI) reduction, which also followed zero-order kinetics. Chromium removal was quantitative only when the initial chromium concentration was lower than 140mgL−1. Reduced chromium was mainly in the solution phase together with dissolved iron. Precipitation with NaOH was therefore required to definitively remove dissolved metals from the investigated system. [Copyright &y& Elsevier]

Abstract: Photochemical and photocatalytic reaction and the combination of both for the oxidation of phenol in aqueous solution were investigated. Photochemical reaction was carried out using three different types of oxidants in the presence of UV radiation while photocatalytic reaction was carried out on zinc oxide under UV radiation. Three different oxidants viz peroxymonosulphate (PMS), peroxydisulphate (PDS) and hydrogen peroxide (H2O2) were employed to generate active sulphate/hydroxyl radicals for oxidation. The synergetic effect of combination of UV/oxidant/ZnO was investigated for the three different oxidant systems. It was found that homogeneous photochemical oxidation of phenol using PMS, PDS or H2O2 exhibited much better performance than heterogeneous photocatalytic oxidation using UV/ZnO. The combination of photochemical and photocatalytic oxidation by combining UV/oxidant with ZnO at low UV radiation showed different degradation trends depending on the oxidant. Scattering of UV radiation in UV/PDS/ZnO and UV/H2O2/ZnO systems showed a slower rate of phenol degradation as compared to the photochemical oxidation under UV/PDS and UV/H2O2 systems. However, UV/PMS/ZnO showed higher rate of phenol oxidation as compared to the photochemical oxidation under UV/PMS, which was mainly attributed to the self-chemical reaction between ZnO and PMS. The phenol degradation in UV/PMS/ZnO followed the first-order kinetics while the phenol degradation resulted from the self-chemical reaction of ZnO/PMS followed zero-order kinetics. [ABSTRACT FROM AUTHOR]

The present study accentuates at the employment of transition metal doped strontium hexagonal ferrites (SrMFe 11 O 19 , M = Cr, Mn, Fe, Co, Cu and Zn) as catalyst for the instigation of potassium peroxymonosulphate towards contaminant degradation for the first time. The successful synthesis of the catalyst was established via numerous techniques such as XRD, FE-SEM, HR-TEM and VSM. The powder X-ray diffraction patterns confirmed the successful formation of hexagonal phase with P63/mmc space group. The detailed surface structure of the synthesized materials was scrutinized through FE-SEM and HR-TEM techniques showcasing hexagonal morphology as predicted by powder XRD technique. The comparative evaluation of catalytic performance of synthesized materials towards the activation of two inorganic oxidants (Hydrogen Peroxide and Potassium Peroxymonosulphate) was carried out for the oxidative degradation of methylene blue, methyl orange, p-nitro phenol and tetracycline. All the synthesized materials were perceived to be highly competent towards the degradation of model pollutants. SrMnFe 11 O 19 portrayed best performance for the oxidative-degradation of model pollutants with rate constant values 1.74 × 10−1 min−1 for MB, 3.04 × 10−1 min−1 for MO, 1.27 × 10−1 min−1 for PNP and 0.73 × 10−1 min−1 for TC using HP as oxidant and 0.39 × 10−1 min−1 for MB, 2.90 × 10−1 min−1 for MO, 0.69 × 10−1 min−1 for PNP and 1.69 × 10−1 min−1 for TC using PMS as oxidant. PMS was witnessed to be a better oxidant in contrast with HP owing to its applicability at wider pH range and higher selectivity; moreover it does not entail any external light source for stimulation. ga1 • Fabrication of SrMFe 11 O 19 (M = Cr, Mn, Fe, Co, Cu and Zn) via chemical co-precipitation method. • Catalytic performance increased via incorporation of Mn, Cu, Co and Cr ions into the lattice. • Mn, Cu, Co and Cr ions prefer surface exposed catalytically active octahedral sites. • Oxidative degradation of pollutants via Hydrogen Peroxide and Potassium Peroxymonosulphate. [ABSTRACT FROM AUTHOR]

• A synergistic effect between sonolysis and Fenton-like reaction has been achieved. • Pyrite/PMS/US system was the most efficient for the PMS decomposition. • SO 4 − radicals prevailed over HO for 2,4-DCP reaction in pyrite/PMS/US system. • The possible degradation pathways of 2,4-DCP were proposed. • A mechanism of 2,4-DCP degradation by pyrite/PMS/US system was summarized. In this paper, the natural pyrite was firstly used as peroxymonosulphate (PMS) activator in conjunction with ultrasonic irradiation (US) for 2,4-dichlorophenol (2,4-DCP) degradation in water. The most relevant findings indicated that a superior degradation of 2,4-DCP has been successfully achieved in pyrite/PMS/US system compared with pyrite/PMS and/or pyrite/US systems, which involved a synergistic effect between sonolysis and Fenton-like reaction. Within 120 min, nearly 98% of 2,4-DCP could be degraded at optimum reaction conditions of pyrite 1.00 g L−1, 2,4-DCP 10 mg L−1, PMS 2.00 mM and pH 4.02. A significantly enhanced PMS decomposition was probably ascribed to the sonochemistry (PMS/US and pyrite/US systems) and catalytic chemistry (pyrite/PMS system) under acidic conditions. Both SO 4 − and HO took part in reaction process, while the SO 4 − was dominant for 2,4-DCP degradation. A total of six intermediate products including 3,5-dichlorocatechol, 2-chlorophenol, 4-chlorocatechol, hydroquinone, maleic acid and oxalic acid were identified using GC/MS analyses to clarify the possible degradation pathways, which involved hydroxylation and substitution reactions. Compared to other Fenton reaction systems, both maximum degradation and mineralization levels of 2,4-DCP have been obtained from pyrite/PMS/US system. This study provides an interesting insight for PMS activation by the natural mineral-based catalyst with US irradiation for in situ organic pollutants remediation. [ABSTRACT FROM AUTHOR]