Bisphenol A degradation by peroxymonosulfate photo-activation coupled with carbon-based cobalt ferrite nanocomposite: Performance, upgrading synergy and mechanistic pathway

Activated persulfate for efficient bisphenol A degradation via nitrogen-doped Fe/Mn bimetallic biochar

To achieve the purpose of treating waste by waste, in this study, a nitrogen-doped Fe/Mn bimetallic biochar material (FeMn@N-BC) was prepared from chicken manure for persulfate activation to degrade Bisphenol A (BPA). The FeMn@N-BC was characterized by scanning electron microscopy (SEM), X-ray diffract meter (XRD), fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectrometer (XPS) and found that N doping can form larger specific surface area. Catalytic degradation experiments showed that Fe/Mn bimetal doping not only accelerated the electron cycling rate on the catalyst surface, but also makes the biochar magnetic and easy to separate, thus reducing environmental pollution. Comparative experiments was concluded that the highest degradation efficiency of BPA was achieved when the mass ratios of urea and chicken manure, Fe/Mn were 3:1 and 2:1, respectively, and the pyrolysis temperature was 800 °C, which can almost degrade all the BPA in 60 min. FeMn@N-BC/PS system with high catalytic efficiency and low consumables is promising for reuse of waste resources and the remediation of wastewater.

Catalytic PMS oxidation universality of CuFe2O4/MnO2 heterojunctions at multiple application scenarios

The magnetic CuFe2O4/MnO2 heterojunctions were prepared by hydrothermal method, and the effect of different reaction temperature on the physicochemical properties and catalytic activity was investigated. The CuFe2O4/MnO2 heterojunctions prepared at 100 °C can effectively activate peroxymonosulfate (PMS) at multiple application scenarios for degradation and mineralization of tetracycline, o-nitrophenol and ceftriaxone sodium under indoor light, visible light and dark condition. Additionally, the CuFe2O4/MnO2-PMS system showed high catalytic activity and anti-interference ability for degradation of pharmaceutical pollutants in natural water bodies and industrial wastewater. The TC removal efficiency in Qianhu Lake water, Ganjiang River water and tap water was about 88%, 92% and 89%, respectively. The CuFe2O4/MnO2-PMS system is also effective for actual pharmaceutical wastewater treatment with 77.9% of COD removal efficiency. Interestingly, the reactive species of CuFe2O4/MnO2-PMS system under visible light are different from those in dark condition, and the different catalytic mechanisms at multiple application scenarios were proposed. This work provides new insights into mechanism exploration of heterojunction catalyst for PMS activation.

Treatment of landfill leachate using photocatalytic based advanced oxidation process - a critical review

Landfill leachate is a discrete volumetric component of municipal solid waste; hence, researchers and professionals are more concerned about it because of its obscurity. Innovative treatment and emerging technologies are being scrutinized to address the treatment of landfill leachate challenges. The leading target of this review was to examine the possibility of removing recalcitrant organic pollutants from landfill leachate by photocatalytic-based advanced oxidation processes. A summary of the systematic applicability of conventional treatment for landfill leachate is provided, with a focus on physico-chemical and biological processes. The biological treatment, such as aerobic and anaerobic digestion, is an excellent technique for treating highly concentrated organic pollutants in the wastewater. However, Leachate can scarcely be treated using conventional techniques since it is enriched with refractory organics and inorganic ions. It is clear from the literature review that none of the available combinations of physico-chemical and biological treatments are entirely relevant for the removal of recalcitrant organic pollutants from leachate. Recently, the photo-assisted TiO2/ZnO oxidation has shown an excessively potential and feasible way to treat landfill leachate. TiO2/ZnO photocatalysis is currently developing to treat recalcitrant organic pollutants from landfill leachate. The effect of operating parameters reveals that pH and temperature affect the reaction rate. The addition of oxidant H2O2 to the TiO2/ZnO suspension suggests that TiO2 leads to an increase in the rate of reaction when compared to ZnO. Photocatalytic remediation technique of landfill leachate would support the goal of environmental sustainability by greatly enhancing the effectiveness of treated leachate reutilization. In this review, the selection of the best photocatalytic treatment for leachate based on its systematic relevance and potential conditions, characteristics, cost-effectiveness, essential controlling, discharge limit, long-term environmental effects, and its future study perspectives are emphasized and discussed.

High-performance Cu/Mn modified ceramsite as a persulfate activator to degrade oxytetracycline in batch Erlenmeyer flask and continuous-flow fixed-bed column systems: An exploration of its practicability and non-radical mechanisms

Persulfate non-radical oxidation have excellent catalytic capability for degrading specific contaminants in complicated water environments. Nevertheless, the preparation of high-performance activators and their application in actual water treatment in continuous flow mode are still scarce and unsatisfactory. In this work, copper-, manganese-, and copper/manganese-doped ceramsites (Cu-C, Mn-C and Cu/Mn-C), successfully fabricated through a facile impregnation-calcination approach, were characterized and evaluated for their performance to activate potassium peroxydisulfate (PDS) and degrade oxytetracycline (OTC) under different pH, ceramsite dosages, and PDS dosages. Compared with Cu-C and Mn-C, Cu/Mn-C showed the highest OTC degradation rate (0.0264 min-1) via activating PDS with an OTC removal efficiency of 98.2% in 240 min at an initial OTC concentration of 40 mg/L. The removal efficiency of OTC by Cu/Mn-C only decreased to 92.8% after 5 cycles; the activating ability of the used Cu/Mn-C was almost completely recovered through 2 h of calcination at 500 °C. The results of electron paramagnetic resonance and radical quenching suggest that singlet oxygen (1O2) was unveiled to be the dominant reactive oxygen species (ROS) for contaminant degradation, originating from the regrouping of superoxide ions or reduction of active Cu/Mn sites. Synergies between Cu and Mn species to enhance ROS yield were the primary activating mechanisms. Six possible routes of OTC decomposition were inferred. Additionally, Cu/Mn-C behaved excellently in treating an actual wastewater using a continuous flow fixed-bed reactor. It is believed that this novel Cu/Mn-C/PDS system may create a fresh path to design effective and cheap metal-ceramsite hybrid activators for degrading recalcitrant contaminants in the actual application process.

The synergistic degradation of pollutants in water by photocatalysis and PMS activation

In recent years, the synergistic degradation of water pollutants through advanced oxidation technology has emerged as a prominent research area due to its integration of various advanced oxidation technologies. The combined utilization of peroxymonosulfate (PMS) activation technology and photocatalysis demonstrates mild and nontoxic characteristics, enabling the degradation of water pollutants across a wide pH range. Moreover, this approach reduces the efficiency of electron hole recombination, broadens the catalyst's light response range, facilitates electron transfer of PMS, and ultimately improves its photocatalytic performance. The paper reviews the current research status of photocatalytic technology and PMS activation technology, respectively, while highlighting the advancements achieved through the integration of photocatalytic synergetic PMS activation technology for water pollutant degradation. Furthermore, this review delves into the mechanisms involving both free radicals and nonradicals in the reaction process and presents a promising prospect for future development in water treatment technology. PRACTITIONER POINTS: Degradation of water pollutants by photocatalysis and PMS synergistic action has emerged. Synergism can enhance the generation of free radicals. This technology can provide theoretical support for actual wastewater treatment.

Peroxymonosulfate activation by Fe-N-S co-doped tremella-like carbocatalyst for degradation of bisphenol A: Synergistic effect of pyridine N, Fe-Nx, thiophene S

Bisphenol A (BPA) has received increasing attention due to its long-term industrial application and persistence in environmental pollution. Iron-based carbon catalyst activation of peroxymonosulfate (PMS) shows a good prospect for effective elimination of recalcitrant contaminants in water. Herein, considering the problem about the leaching of iron ions and the optimization of heteroatoms doping, the iron, nitrogen and sulfur co-doped tremella-like carbon catalyst (Fe-NS@C) was rationally designed using very little iron, S-C₃N₄ and low-cost chitosan (CS) via the impregnation-calcination method. The as-prepared Fe-NS@C exhibited excellent performance for complete removal of BPA (20 mg/L) by activating PMS with the high kinetic constant (1.492 min^-1) in 15 min. Besides, the Fe-NS@C/PMS system not only possessed wide pH adaptation and high resistance to environmental interference, but also maintained an excellent degradation efficiency on different pollutants. Impressively, increased S-C₃N₄ doping amount modulated the contents of different N species in Fe-NS@C, and the catalytic activity of Fe-NS@C-1-x was visibly enhanced with increasing S-C₃N₄ contents, verifying pyridine N and Fe-N_x as main active sites in the system. Meanwhile, thiophene sulfur (C-S-C) as active sites played an auxiliary role. Furthermore, quenching experiment, EPR analysis and electrochemical test proved that surface-bound radicals (^·OH and SO₄^⋅-) and non-radical pathways worked in the BPA degradation (the former played a dominant role). Finally, possible BPA degradation route were proposed. This work provided a promising way to synthesize the novel Fe, N and S co-doping carbon catalyst for degrading organic pollutants with low metal leaching and high catalytic ability.

Spinel cobalt ferrite-based porous activated carbon in conjunction with UV light irradiation for boosting peroxymonosulfate oxidation of bisphenol A

Developing heterogeneous catalysts with high performance for peroxymonosulfate (PMS) activation to decontaminate organic pollutants from wastewater is of prominent importance. In this study, spinel cobalt ferrite (CoFe₂O₄) materials were coated on the surface of powdered activated carbon (CoFe₂O₄@PAC) via the facile co-precipitation method. The high specific surface area of PAC was beneficial for the adsorption of both bisphenol A (BP-A) and PMS molecules. The CoFe₂O₄@PAC-mediated PMS activation process under UV light could effectively eliminate 99.4% of the BP-A within 60 min of reaction. A significant synergy effect was attained between CoFe₂O₄ and PAC towards PMS activation and subsequent elimination of BP-A. Comparative tests demonstrated that the heterogeneous CoFe₂O₄@PAC catalyst had a better degradation performance in comparison with its components and homogeneous catalysts (Fe, Co, and, Fe + Co ions). The formed by-products and intermediates during BP-A decontamination were evaluated using LC/MS analysis, and then a possible degradation pathway was proposed. Moreover, the prepared catalyst exhibited excellent performance in recyclability with slight leaching amounts of Co and Fe ions. A TOC conversion of 38% was obtained after five consecutive reaction cycles. It can be concluded that the PMS photo-activation process via the CoFe₂O₄@PAC catalyst can be utilized as an effective and promising method for the degradation of organic contaminants from polluted-water resources.

Stable and recyclable FeS-CMC-based peroxydisulfate activation for effective bisphenol A reduction: performance and mechanism

In this study, a novel material, iron sulfide modified by sodium carboxymethyl cellulose (FeS-CMC), was successfully synthetized for peroxydisulfate (PDS) activation to remove bisphenol A (BPA). Characterization results showed that FeS-CMC had more attachment sites for PDS activation due to its higher specific surface area. A stronger negative potential contributed to preventing nanoparticles from reuniting in the reaction and improving the interparticle electrostatic interactions of the materials. Fourier transform infrared spectrometer (FTIR) analysis of FeS-CMC suggested that the coordination of the ligand for combining sodium carboxymethyl cellulose (CMC) with FeS was monodentate. A total of 98.4% BPA was decomposed by the FeS-CMC/PDS system after 20 min under optimized conditions (pH = 3.60, [FeS-CMC] = 0.05 g/L and [PDS] = 0.88 mM). The isoelectric point (pH_pzc) of FeS-CMC is 5.20, and FeS-CMC contributed to reducing BPA under acidic conditions but showed a negative effect under basic conditions. The presence of HCO₃^-, NO₃^- and HA inhibited BPA degradation by FeS-CMC/PDS, while excess Cl^- accelerated the reaction. FeS-CMC exhibited excellent performance in oxidation resistance with a final removal degree of 95.0%, while FeS was only 20.0%. Furthermore, FeS-CMC showed excellent reusability and still reached 90.2% after triple reusability experiments. The study confirmed that the homogeneous reaction was the primary part of the system. Surface-bound Fe(II) and S (-II) were found to be the major electron donors during activation, and the reduction of S (-II) contributed to the cycle of Fe(III)/Fe(II). Sulfate radicals (SO₄^•-), hydroxyl radicals (•OH), superoxide radicals (O₂^•-) and singlet oxygen (¹O₂) were produced at the surface of FeS-CMC and accelerated the decomposition of BPA. This study offered a theoretical basis for improving the oxidation resistance and reusability of iron-based materials in the presence of advanced oxidation processes.

Magnetic CuFe2O4 nanoparticles anchored on N-doped carbon for activated peroxymonosulfate removal of oxytetracycline from water: Radical and non-radical pathways

In this work, magnetic CuFe₂O₄ was prepared for the removal of oxytetracycline (OTC) by a self-propagating combustion synthesis method. Almost complete degradation (99.65%) of OTC was achieved within 25 min at [OTC]₀ = 10 mg/L, [PMS]₀ = 0.05 mM, CuFe₂O₄ = 0.1 g/L under pH = 6.8 at 25 °C for deionized water. Specially, the addition CO₃^2- and HCO₃^- induced the CO₃•^- appearance enhancing the selective degradation to electron-rich OTC molecule. The prepared CuFe₂O₄ catalyst exhibited desirable OTC removal rate (87.91%) even in hospital wastewater. The reactive substances were analyzed by free radical quenching experiments and electron paramagnetic resonance (EPR), and the results demonstrated that ¹O₂ and •OH were the main active substances. Liquid chromatography-mass spectrometry (LC-MS) was used to analyze the intermediates produced during the degradation of OTC and thus to speculate on the possible degradation pathways. Ecotoxicological studies were conducted to unveil large-scale application prospect.

Bisphenol A monitoring during anaerobic degradation of papers with thermochromic prints in soil

Pseudoestrogene bisphenol A (BPA) can be important ingredient of thermochromic inks, increasingly used materials in thermal printing paper, security printing, advertising, design and as temperature indicators in medicine and food industry. BPA mass fraction in thermochromic inks can be up to several percent. Hence, disposal of items with thermochromic prints pose a risk of environmental pollution. In this work BPA mass fraction was monitored during anaerobic degradation of papers with thermochromic prints in soil in both matrices: papers and soil. The degradation conditions simulated deeper layers of waste at a landfill site. Six types of papers with prints of thermochromic ink containing 2% of BPA were subjected to anaerobic degradation over up to 150 days. Initial mass fractions of BPA in papers decreased form (126-460) μg/g to (<QL - 45) μg/g after 150 days. BPA amounts were reduced 10 to 50 times depending on the paper type: least for synthetic paper and most for wood-free coated. For soil analysis new HPLC-UV method was developed and validated. The method was linear from 0.75 ng/g to 0.6 μg/g of BPA in soil with correlation coefficient of 0.9994. Method precision was 4.4%, accuracy 83% and detection limit 0.9 ng/g. Expectedly, amount of BPA in soil was increasing during the experiment. Mass fractions of BPA in soil were from not detected in earlier stage of degradation to (4.9-23.2) ng/g after 150 days. Final BPA amounts in soil were similar to those found in industrial, urban and agricultural soils worldwide. Hence, BPA from papers with thermochromic prints was notably decomposed, and contaminated soil had the capacity to absorb and decompose BPA even under anaerobic conditions. After 150 days of anaerobic degradation, only up to 1.86% of BPA contained in paper prints was found in soil, whilst, on average, 4% of initial BPA remained in paper.

Synergetic Photocatalytic Peroxymonosulfate Oxidation of Benzotriazole by Copper Ferrite Spinel: Factors and Mechanism Analysis

The development of oxidation processes with the efficient generation of powerful radicals is the most interesting and thought-provoking dimension of peroxymonosulfate (PMS) activation. This study reports the successful preparation of a magnetic spinel of CuFe₂O₄ using a facile, non-toxic, and cost-efficient co-precipitation method. The prepared material exhibited a synergetic effect with photocatalytic PMS oxidation, which was effective in degrading the recalcitrant benzotriazole (BTA). Moreover, central composite design (CCD) analysis confirmed that the highest BTA degradation rate reached 81.4% after 70 min of irradiation time under the optimum operating conditions of CuFe₂O₄ = 0.4 g L^-1, PMS = 2 mM, and BTA = 20 mg L^-1. Furthermore, the active species capture experiments conducted in this study revealed the influence of various species, including ^•OH, SO₄^•-, O₂^•-, and h⁺ in the CuFe₂O₄/UV/PMS system. The results showed that SO₄^•- played a predominant role in BTA photodegradation. The combination of photocatalysis and PMS activation enhanced the consumption of metal ions in the redox cycle reactions, thus minimizing metal ion leaching. Additionally, this maintained the reusability of the catalyst with reasonable mineralization efficiency, which reached more than 40% total organic carbon removal after four batch experiments. The presence of common inorganic anions was found to have a retardant effect on BTA oxidation, with the order of retardation following: HCO₃^- > Cl^- > NO₃^- > SO₄^2-. Overall, this work demonstrated a simple and environmentally benign strategy to exploit the synergy between the photocatalytic activity of CuFe₂O₄ and PMS activation for the treatment of wastewater contaminated with widely used industrial chemicals such as BTA.

Facile fabrication of mesoporous carbon-anchored cobalt ferrite nanoparticles as a heterogeneous activator of peroxymonosulfate for efficient degradation of Congo red

Herein, mesoporous carbon-anchored cobalt ferrite nanocomposites (nano-CoFe₂O₄@MC) were fabricated using a hydrothermal method for application as heterogeneous catalysts to activate peroxymonosulfate (PMS), in order to solve the problems of low activation performance and secondary pollution caused by the inter-particle agglomeration, metal ion leaching, and difficult recovery of nano metal catalysts. Analysis techniques such as SEM, TEM, XRD, BET, FTIR, VSM, TGA, and Raman spectroscopy indicated that the prepared nanocomposites have excellent surface properties, structural stability, and magnetic properties. The performance of nano-CoFe₂O₄@MC for Congo red (CR) degradation was evaluated by comparison with other treatment systems and study of the influence of experimental parameters, including the anchoring ratios, catalyst dosage, PMS concentration, initial pH, CR concentration, coexisting anions, and humic acid. Both radical and nonradical pathways were observed in the activation process of PMS by nano-CoFe₂O₄@MC. The analysis results of the element composition and ionic state of the catalyst show that the redox cycle of two ion pairs, Co³⁺/Co²⁺ and Fe²⁺/Fe³⁺, could enhance the multipath electron transfer on the catalyst surface to promote the generation of reactive oxygen species. Identification of the intermediate products revealed CR was transformed into 12 intermediates through two branch pathways in the nano-CoFe₂O₄@MC/PMS system. After five cycles of use, the catalytic efficiency of the catalyst did not decrease significantly. Nanocomposites with high catalytic performance, stability, recyclability, and a low ion leaching rate have broad application prospects in the treatment of antibiotic wastewater.

Resourcelized conversion of livestock manure to porous cage microsphere for eliminating emerging contaminants under peroxymonosulfate trigger

Pollution and resource waste caused by the improper disposal of livestock manure, and the threat from the release of emerging contaminants (ECs), are global challenges. Herein, we address the both problems simultaneously by the resourcelized conversion of chicken manure into porous Co@CM cage microspheres (CCM-CMSs) for ECs degradation through the graphitization process and Co-doping modification step. CCM-CMSs exhibit excellent performance for ECs degradation and actual wastewater purification under peroxymonosulfate (PMS) initiation, and show adaptability to complex water environments. The ultra-high activity can maintain after continuous operation over 2160 cycles. The formation of C-O-Co bond bridge structure on the catalyst surface caused an unbalanced electron distribution, which allows PMS to trigger the sustainable electron donation of ECs and electron gain of dissolved oxygen processes, becoming the key to the excellent performance of CCM-CMSs. This process significantly reduces the resource and energy consumption of the catalyst throughout the life cycle of production and application.

Graphene-magnetite functionalized diatomite for efficient removal of organochlorine pesticides from aquatic environment

A unique composite based on graphene oxide, magnetite, and diatomite was synthetized by eco-friendly dry coating technique for the removal of four toxic organochlorine pesticides from agricultural drainage. The prepared composite was fully characterized using X-ray fluorescence (XRF), X-ray diffraction (XRD), particle size analyzer, Vibrating-sample magnetometer (VSM), magnetic susceptibility meter, zeta potential, scanning electron microscopy-energy dispersive X-ray spectrometer (SEM-EDS), and Brunauer-Emmett-Teller analysis (BET) techniques. The characterization results confirmed the fabrication of a discrete core/shell structured composite possess both adsorptive and magnetic nature. The surface area, pore volume and pore diameter were 23.4 m²/g, 0.0026 cm³/g, and 4.5 nm, respectively. The amenability to use the fabricated composite as an adsorbent for some organochlorine pesticides was investigated under different conditions of concentration, time, pH, and temperature. Batch adsorption experiment showed that 97% removal efficiency was observed for all the studied pesticides with adsorption capacities of 7.78 mg/g after 2 h contact time and at any pH region. The adsorption was exothermic (ΔH < 0), spontaneous (ΔG° < 0), followed pseudo 2nd order kinetics (R² > 0.998), and fitted well to Langmuir's isotherm pattern for all pesticides (R² > 0.98). It is assumed that organochlorine pesticides were initially physisorbed by the graphene nanoplatelets via hydrophobic and π-π interactions along with chemisorption for forming monolayer. Moreover, the pesticides molecules could diffuse in the DMG composite micropores and be trapped in the structural defects. The regeneration of the composite exhibited over 90% removal efficiency even after seven cycles. The fabricated composite was examined to remove organochlorine from a real water sample, the obtained results suggest the possibility to use this composite as an economical, effective and sustainable adsorbent for the treatment of pesticides contaminating water.

Significant roles of surface functional groups and Fe/Co redox reactions on peroxymonosulfate activation by hydrochar-supported cobalt ferrite for simultaneous degradation of monochlorobenzene and p-chloroaniline

CoFe₂O₄/hydrochar composites (FeCo@HC) were synthesized via a facile one-step hydrothermal method and utilized to activate peroxymonosulfate (PMS) for simultaneous degradation of monochlorobenzene (MCB) and p-chloroaniline (PCA). Additionally, the effects of humic acid, Cl^-, HCO₃^-, H₂PO₄^-, HPO₄^2- and water matrices were investigated and degradation pathways of MCB and PCA were proposed. The removal efficiencies of MCB and PCA were higher in FeCo@HC140-10/PMS system obtained under hydrothermal temperature of 140 °C than FeCo@HC180-10/PMS and FeCo@HC220-10/PMS systems obtained under higher temperatures. Radical species (i.e., SO₄^•-, •OH) and nonradical pathways (i.e., ¹O₂, Fe (IV)/Co (IV) and electron transfer through surface FeCo@HC140-10/PMS* complex) co-occurred in the FeCo@HC140-10/PMS system, while radical and nonradical pathways were dominant in degrading MCB and PCA respectively. The surface functional groups (i.e., C-OH and CO) and Fe/Co redox cycles played crucial roles in the PMS activation. MCB degradation was significantly inhibited in the mixed MCB/PCA solution over that in the single MCB solution, whereas PCA degradation was slightly promoted in the mixed MCB/PCA solution. These findings are significant for the provision of a low-cost and environmentally-benign synthesis of bimetal-hydrochar composites and more detailed understanding of the related mechanisms on PMS activation for simultaneous removal of the mixed contaminants in groundwater.

2D MOF derived cobalt and nitrogen-doped ultrathin oxygen-rich carbon nanosheets for efficient Fenton-like catalysis: Tuning effect of oxygen functional groups in close vicinity to Co-N sites

Developing highly efficient catalysts for peroxymonosulfate (PMS) activation is an important issue in advanced oxidation processes (AOPs) technology. In this work, cobalt and nitrogen-doped ultrathin oxygen-rich carbon nanosheets derived from 2D metal-organic framework (MOF) were successfully fabricated. The as-prepared catalyst can effectively degrade tetracycline (TC) with a high reaction constant (0.088 min^-1). Quenching test, electron paramagnetic resonance (EPR) technology, and the electrochemical test indicate that the radical pathway plays a minor role in the degradation process, the ¹O₂ based nonradical pathway dominates the reaction. Experimental and density functional theory (DFT) studies revealed that the Co-N sites on the carbon structure serve as the dominant active sites, and the oxygen functional groups in close vicinity to Co-N sites can dramatically influence local electronic structure and its interaction with PMS molecule, a high correlation between the reaction constant and hydroxy groups content could be due to the Co-N sites close to hydroxyl groups has a moderate PMS adsorption energy. This work provides new insight into the design of highly efficient Fenton-like catalysts.

Catalytic activation of peroxydisulfate by secondary mineral derived self-modified iron-based composite for florfenicol degradation: Performance and mechanism

The advanced oxidation processes (AOPs) driven by iron-based materials are the highly efficient technology for refractory organic pollutants treatment. In this work, self-modified iron-based catalysts were prepared using secondary mineral as the precursor by one-step pyrolysis process without additional dopants. The prepared catalysts exhibited excellent performance in catalytic degradation of florfenicol (FF), especially C-AJ, which was derived from ammoniojarosite [(NH₄, H₃O)Fe₃(OH)₆(SO₄)₂], activated PDS to degrade 93% FF with initial concentration of 50 mg/L. Quenching tests and electron paramagnetic resonance (ESR) studies showed that SO₄^•-, ^•OH, and ^•O₂^- were the main reactive species for FF degradation and their contribution degree was SO₄^•- > ^•OH > •O₂^-. The Fe⁰ and the cycle of Fe(II)/Fe(III) both contributed to the PDS activation, and the reduction of Fe(III) to Fe(II) was accelerated by S^2- on the catalyst surface. In addition, Fe₃O₄ on the C-AJ indirectly catalyzes PDS by promoting electron transfer. The effects of catalyst dosage, PDS concentration, pH, inorganic anions, and real aqueous matrices on FF degradation, TOC analysis, and cycling test were investigated. The results showed that iron-based catalysts have superior environmental durability due to their excellent catalytic properties in the real aqueous matrices with common inorganic anions and pH 3-9 and its steady catalytic capacity with multiple cycles. Overall, this study sheds new light on the rational design of self-modified iron-based composite and develops low-cost technology toward remediation of FF-contaminated wastewater.

Core-shell magnetic CFO@COF composites toward peroxymonosulfate activation for degradation of sulfamethoxazole from aqueous solution: A comparative study and mechanistic consideration

A core-shell covalent organic framework encapsulated Co1.2Fe1.8O4 magnetic particles (CFO@COF) was designed and prepared successfully to activate peroxymonosulfate (PMS) for sulfamethoxazole (SMX) degradation. It displays amazing catalytic reactivity since the unique interior structure and synergistic effect between COF shell and CFO core, reaching 99.8% removal of SMX (10 mg/L) within 30 min and 90.8% TOC removal. The synergy between bimetals vests high reactivity to CFO core. And the outer COF shell can stabilize the CFO core under intricate reaction conditions to restrain the leaching of Co ions (decreased from 0.75 to 0.25 mg/L). Further investigation compared the activation mechanism in two different system, CFO/PMS system and CFO@COF/PMS system. The result showed that the radical mechanism controlled by SO4⋅- guided the SMX degradation in CFO/PMS system whereas the 1O2 played a pivotal role in CFO@COF/PMS system called non-radical leading. The influences of various factors on degradation experiments and SMX degradation pathway were also studied. Most importantly, risk assessment in CFO@COF/PMS/SMX system was estimated via "ecological structure activity relationships". In most case, the toxicities of intermediates were lower than the initial samples, which confirmed the effectiveness of CFO@COF/PMS/SMX system in the reduction of toxicity of SMX.

Covalent organic frameworks@ZIF-67 derived novel nanocomposite catalyst effectively activated peroxymonosulfate to degrade organic pollutants

Metal organic frameworks-Covalent organic frameworks (MOFs-COFs) nanocomposites could improve the catalytic performance. Herein, a novel nanocomposite catalyst (CC@Co₃O₄) derived from MOFs-COFs (COF@ZIF-67) was prepared on peroxymonosulfate (PMS) activation for bisphenol A (BPA) and rhodamine B (RhB) degradation. Owing to the Co species, oxygen vacancy (O_V), surface hydroxyl (-OH), graphite N and ketone groups (C=O), the CC@Co₃O₄ exhibited higher catalytic degradation performance and total organic carbon (TOC) for BPA (93.8% and 22.3%) and RhB (98.2% and 82.5%) with a small quantity of catalyst (0.10 g/L) and low concentration of PMS (0.20 g/L) even without pH adjustment. Sulfate radicals (•SO₄^-), hydroxyl radicals (•OH), single oxygen (¹O₂), superoxide radicals (•O₂^-) and electron transfer process were all involved in the degradation of BPA and RhB. Among them, the degradation of BPA and RhB mainly depended on •O₂^- and ¹O₂, respectively. Meanwhile, the degradation pathways of BPA and RhB were proposed, and the biotoxicity of the degradation products was evaluated by freshwater chlorella. The results illustrated that the degradation products were environmentally friendly to organisms. In addition, the role of COF in the nanocomposites was also studied. The addition of COF remarkably improved the catalytic performance of CC@Co₃O₄ due to the faster electron transfer, more graphite N and C=O. Overall, this work may open the door to the development of COF-based catalysts in the field of water pollutant remediation.

Enhancement of peroxymonosulfate activation for 2,4-dichlorophenoxyacetic acid removal by MoSe2 induced Fe redox cycles

The limited regeneration of Fe2+ in the Fe-catalyzed advanced oxidation processes (AOPs) constrained its application for the removal of organic pollutants. Herein, MoSe2 was introduced to promote the degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) in the Fe2+/PMS system. Compared with Fe2+/PMS processes, the 2,4-D degradation efficiency and PMS decomposition rate respectively increased by 73.8% and 84.2% in the MoSe2/Fe2+/PMS system. DFT simulation results suggested that Se atoms acted smoothly as the bridge supporting the charge transfer from Mo to adjacent Fe atoms, which led to the reduction of Fe3+. The rapid regeneration of Fe2+ boosted the activation of PMS and the degradation of pollutants. Additionally, the electron paramagnetic resonance (EPR) and quenching experiments results indicated that SO4∙-, ∙OH, and 1O2 accounted for 2,4-D degradation, and SO4∙- and 1O2 predominated the reaction. The Mo based co-catalysts showed better co-catalytic effect than the W counterparts, and the moderate adsorption for PMS and lower electron transfer electron transfer resistance accounted for the more excellent co-catalytic performance of MoSe2 than that of WSe2. In addition, the degradation efficiency of 2,4-D was up to 95.5% after five cycles of MoSe2 in the co-catalytic system. The coexistent humic acid (HA) and Cl- showed ignorant negative effect on the degradation, while HCO3- would depress the oxidation reaction. The acidic etching wastewater can be applied as the Fe ions source in this co-catalytic process to remove 2,4-D effectively.

Model simulation and mechanism of Fe(0/II/III) cycle activated persulfate degradation of methylparaben based on hydroxylamine enhanced nano-zero-valent iron

The mechanism of Fe²⁺-activated peroxodisulfate (PDS) by hydroxylamine (HA) has been investigated, however, nano zero-valent iron-activated persulfate (nZVI/PDS) has a more optimal effect and needs further investigation. This study investigated the addition of HA to nZVI/PDS to improve Fe²⁺ regeneration and accelerate methylparaben (MP) degradation by Fe (0/II/III) cycle. After 60 min of reaction, the HA-enhanced nZVI/PDS (HA/nZVI/PDS) system afforded a 21% increase in MP degradation, reaching 93.26% (1 mM HA, 1 mM nZVI, and 2 mM PDS). nZVI/PDS system was a second-order reaction, but after adding HA, the reaction was more suitable for the first-order reaction. The addition of HA effectively promoted the reduction of Fe³⁺ to Fe²⁺ to improve the effect and reaction rate of PDS degradation of MP (k increased from 0.0127 min^-1 to 0.0198 min^-1) and broadened the reaction pH range. The results of various characterizations of nZVI before and after the reaction revealed that nZVI changed from a spherical structure to a bundle structure and was slightly oxidized. Changes in the Fe²⁺ and Fe³⁺ concentrations as well as in the pH of the reaction systems were monitored and the possible reactions of the HA/nZVI/PDS system were derived for the first time (k_nZVI/PDS<3.7 × 10⁶ M^-1 s^-1, k_Fe3+/NH2O· >4.2 min^-1). 12 potential compounds were investigated and MP breakdown pathways were speculated; hydroxylation was determined to be the most important pathway of degradation. And the HA/nZVI/PDS system had universal applicability.

Porous boron nitride intercalated zero-valent iron particles for highly efficient elimination of organic contaminants and Cr (VI)

Developing novel bifunctional materials to high efficiently degrade organic pollutants and eliminate hexavalent chromium (Cr (VI)) is significantly desired in the wastewater treatment field. The porous boron nitride (p-BN) was fabricated by a two-stage calcination strategy and was innovatively employed to support zero-valent iron (ZVI), achieving the bifunctional material (p-BN@ZVI) to degrade carbamazepine (CBZ) and eliminate Cr (VI). p-BN@ZVI could degrade more than 98% CBZ in 6 min with the high apparent first-order constant (k_obs) of 0.536 min^-1, almost 5 times higher than that of the ZVI/PMS system and outperformed most previous reported ZVI supported catalysts, which was mainly ascribed to the fact that the introduction of p-BN with high surface area (793.97 m²/g) improved the dispersion of ZVI and exposed more active sites. Quenching tests coupled with electron paramagnetic resonance (EPR) suggested that •OH was the major reactive oxygen species with a contribution of 71.6%. Notably, the p-BN@ZVI/PMS system expressed low activation energy of 8.23 kJ/mol and reached a 65.69% TOC degradation in 20 min even at 0 °C. p-BN@ZVI possessed remarkable storage stability and could still degrade 92.3% CBZ despite three-month storage. More interestingly, p-BN@ZVI was capable to eliminate 98.1% of 50 mg/L Cr (VI) within 5 min through adsorption and reduction, where nearly 80% Cr (VI) was transformed to Cr (III), and exhibited the maximum Cr (VI) elimination capacity of 349 mg/g. This study provides new insights into the efficient organic contaminants degradation and Cr (VI) elimination in the treatment of wastewater.

Photocatalytic and Antibacterial Activity of CoFe2O4 Nanoparticles from Hibiscus rosa-sinensis Plant Extract

Biogenic CoFe₂O₄ nanoparticles were prepared by co-precipitation and Hibiscus rosa sinensis plant leaf was used as a bio-reductant of the nanoparticle productions. The biosynthesized CoFe₂O₄ nanoparticles were characterized by XRD, FTIR, UV, VSM, and SEM via EDX analysis. The cubic phase of biosynthesized CoFe₂O₄ nanoparticles and their crystallite size was determined by XRD. The Co-Fe-O bonding and cation displacement was confirmed by FTIR spectroscopy. The presence of spherically-shaped biosynthesized CoFe₂O₄ nanoparticles and their material were confirmed by SEM and TEM via EDX. The super-paramagnetic behaviour of the biosynthesized CoFe₂O₄ nanoparticles and magnetic pulse was established by VSM analysis. Organic and bacterial pollutants were eradicated using the biosynthesized CoFe₂O₄ nanoparticles. The spinel ferrite biosynthesized CoFe₂O₄ nanoparticles generate radical and superoxide ions, which degrade toxic organic and bacterial pollutants in the environment.

Metal-free single heteroatom (N, O, and B)-doped coconut-shell biochar for enhancing the degradation of sulfathiazole antibiotics by peroxymonosulfate and its effects on bacterial community dynamics

Metal-free single heteroatom (N, O, and B)-doped coconut-shell biochar (denoted as N-CSBC, O-CSBC, and B-CSBC, respectively) were fabricated in a one-step pyrolysis process to promote peroxymonosulfate (PMS) activation for the elimination of sulfathiazole (STZ) from aquaculture water. B-CSBC exhibited remarkably high catalytic activity with 92% of STZ degradation in 30 min attributed to the presence of meso-/micro-pores and B-containing functional groups (including B-N, B-C, and B₂O₃ species). Radical quenching tests revealed SO₄^•-, HO•, and ¹O₂ being the major electron acceptors contributing to STZ removal by PMS over B-CSBC catalyst. The B-CSBC catalyst has demonstrated high sustainability in multiple consecutive treatment cycles. High salinity and the presence of inorganic ions such as chloride, enhanced the performance of the sulfate radical-carbon-driven advanced oxidation processes (SR-CAOPs) as pretreatment strategy that significantly facilitated the removal of STZ from aquaculture water. Furthermore, a potential sulfonamide-degrading microorganism, Cylindrospermum_stagnale, belonging to the phylum Cyanobacteria, was the dominant functional bacteria according to the results of high-throughput 16S rRNA gene sequencing conducted after the B-CSBC/PMS treatment. This study provides new insights into the SR-CAOP combined with bioprocesses for removing STZ from aqueous environments.

A comprehensive review on BPA degradation by heterogeneous Fenton-like processes

Synthetic organic pollutants emanating continuously in the ecosystem have become a global concern because of their toxicity and persistent nature. Bisphenol A (BPA) is one such pollutant which threatens public health and safety. It is a monomer used in manufacturing plastics, polycarbonate resins, epoxy resins and is a well-recognised endocrine disruptor mimicking estrogen. BPA leaches into food and beverages stored in containers causing contamination issues. Its widespread exposure and potential toxicity is an environmental health concern. In this review, a systematic investigation has been carried out on the heterogeneous catalysts used for Fenton-like processes for BPA degradation. The Fenton-like reaction is one such reaction that is used for wastewater remediation purposes. The reaction advances through the generation of powerful oxidizing radicals like •OH and SO₄^•- in the presence of a suitable catalyst. The application of various Fenton catalysts, with their distinguished morphological characteristics, oxidizing properties, toxicity analysis, and the present state of the art of BPA degradation by these catalysts, have been documented in the current work. This review also highlights a few challenges and prospects for analysing degradation products of landfill leachate.

Performance of a Three-Dimensional Electrochemical Reactor (3DER) on Bisphenol A Degradation

This study constructed a three-dimensional electrochemical reactor (3DER) using meshed stainless steel sheets and titanic magnetite particles (TMP) to investigate bisphenol A (BPA) degradation through the synergistic action of electrical current and TMP. We examined some TMP characteristics, such as particle size, specific surface areas, X-ray diffraction, surface imaging, elemental constituents, and electrical resistivity. It was found that TMP was a micron-level material with excellent electrical conductivity, and it could be regarded as a magnetite-based material comprising Fe(II) and Fe(III). The single-factor experiment determined the optimal conditions for BPA removal in 3DER, specifically by introducing 200 ml of BPA-simulated wastewater (10 mg L⁻¹) into 3DER. At the initial pH of 9.00, current and electrodes gap of 300 mA and 15 mm, respectively, and adding 1 ml of 0.5 M potassium peroxymonosulfate and 1 g TMP, > 98% of BPA was removed after 55 min of electrochemical reaction. In addition, liquid chromatography–mass spectrometry identified the intermediates formed during the BPA treatment, showing two possible pathways for BPA degradation. The final degradation intermediates were chain organics with simple molecular structures. This research provided an understanding of the potential application of 3DER for BPA removal in water.

Efficient peroxymonosulfate activation by N-rich pyridyl-iron phthalocyanine derivative for the elimination of pharmaceutical contaminants under solar irradiation

It is of great significance for improving electron transmission performance by changing of the outer ring structure of iron phthalocyanine. Herein, 4 (pyridine-2, 3-yl) iron phthalocyanine (FepyPc), as N-rich pyridyl-iron phthalocyanine derivative, was introduced to degrade pharmaceutical contaminants. The catalytic degradation of organic pollutants with FepyPc was studied by activating peroxymonosulfate (PMS) at room temperature. The results clarified that the removal rate of carbamazepine (CBZ) was close to 100% within 60 min and the calculated apparent rate constant was about 2 times larger than FePc, which proved that FepyPc had superior performance. Four active species were identified for the degradation of CBZ, including superoxide radical (•O₂^-), singlet oxygen (¹O₂), sulfate radical (SO₄•^-) and hydroxyl radical (•OH). In addition, the possible reaction mechanism was inferred in FepyPc/PMS/sunlight system for CBZ removal. Finally, the CBZ degradation pathway was proposed by using ultra-performance liquid chromatography and high definition mass spectrometry (UPLC/HDMS). This research provided a meaningful and efficient method for the elimination of pharmaceutical contaminants.

Remove of ammoniacal nitrogen wastewater by ultrasound/Mg/Al2O3/O3

A large amount of ammoniacal nitrogen wastewater discharged into the water body not only causes eutrophication and black and offensive odor in water, but also increases the difficulty and cost of water treatment, and even produces toxic effects on people and organisms. In this paper, degradation of ammoniacal nitrogen wastewater by the system of ultrasound/Mg/Al₂O₃/ozone (US/Mg/Al₂O₃/O₃) was carried out. The effects of different influencing factors, such as initial pH of the solution, reaction time, temperature, catalyst addition, ozone flow rate, and ultrasonic intensity, on the degradation of ammoniacal nitrogen wastewater were investigated. The optimum reaction conditions were determined. The combination of ultrasonic technology and ozone oxidation technology can enhance the mass transfer of ozone and generate a large amount of HO. Due to Mg/Al₂O₃ catalyst has large surface area, the number of reactive sites and reaction molecule transport channels per unit area increases, resulting in the increase of HO on the surface, thus improving the catalytic activity. The introduction of ultrasound promotes the cleavage of N-H bonds on the catalyst surface, thereby promoting the degradation of ammoniacal nitrogen in the water. Results prove that there is not only a synergistic effect between ultrasound and catalytic ozone oxidation, but a strengthening effect of ultrasound on catalytic ozone oxidation. The research carried out in this paper provides a theoretical basis for the degradation of ammoniacal nitrogen in water.