Activation Of Oxone Research Articles

Boosting degradation of C4mim cation by metal alkoxide-derived Co4S3-activated Oxone: Yolk-Shell-Engineered enhancement and DFT-assisted toxic evaluation

Boosting degradation of C4mim cation by metal alkoxide-derived Co4S3-activated Oxone: Yolk-Shell-Engineered enhancement and DFT-assisted toxic evaluation

Magnetic Carbon Foam Adorned with Co/Fe Nanoneedles as an Efficient Activator of Oxone for Oxidative Environmental Remediation: Roles of Surficial and Chemical Enhancement

As heterogeneous catalysis is a practical method for activating Oxone, the immobilization of transition metals (e.g., Co, Fe) on carbonaceous supports is a promising platform. Thus, this study attempts to develop a carbon-supported metallic catalyst by growing Co/Fe on carbon foam (CF) via adopting melamine foam as a readily available template which could be transferred to nitrogen-doped CF with marcoporous structures. Specifically, a unique adornment of Co/Fe species on this CF is facilely fabricated through a complexation of Co/Fe with a plant extract, tannic acid, on melamine foam, followed by carbonization to produce nano-needle-like Co/Fe on N-doped CF, forming a magnetic CF (MCF). This resultant MCF exhibits a much higher surface area of 54.6 m2/g than CF (9.5 m2/g), and possesses a much larger specific capacitance of 9.7 F/g, than that of CF as 4.0 F/g. These superior features of MCF enable it to accelerate Oxone activation in order to degrade an emerging contaminant, bis(4-hydroxyphenyl)methanone (BHPM). Furthermore, MCF + Oxone exhibits a lower activation energy as 18.6 kJ/mol for BHPM elimination and retains its effectiveness in eliminating BHPM over multiple rounds. More importantly, the CF is also prepared and directly compared with the MCF to study the composition-structure-property relationship to provide valuable insights for further understanding of catalytic behaviors, surficial characteristics, and application of such a functional carbon material.

Nonradical activation of Oxone over Fe-doped nitrogen carbon (Fe@NC) armor catalysts for efficient degradation of anthropogenic phenolics (p-nitrophenol, 4-chlorophenol) in groundwater matrices

Nonradical activation of Oxone over Fe-doped nitrogen carbon (Fe@NC) armor catalysts for efficient degradation of anthropogenic phenolics (p-nitrophenol, 4-chlorophenol) in groundwater matrices

Hollow-Architected Heteroatom-Doped Carbon-Supported Nanoscale Cu/Co as an Enhanced Magnetic Activator for Oxone to Degrade Toxicants in Water.

Even though transition metals can activate Oxone to degrade toxic contaminants, bimetallic materials possess higher catalytic activities because of synergistic effects, making them more attractive for Oxone activation. Herein, nanoscale CuCo-bearing N-doped carbon (CuCoNC) can be designed to afford a hollow structure as well as CuCo species by adopting cobaltic metal organic frameworks as a template. In contrast to Co-bearing N-doped carbon (CoNC), which lacks the Cu dopant, CuCo alloy nanoparticles (NPs) are contained by the Cu dopant within the carbonaceous matrix, giving CuCoNC more prominent electrochemical properties and larger porous structures and highly nitrogen moieties. CuCoNC, as a result, has a significantly higher capability compared to CoNC and Co3O4 NPs, for Oxone activation to degrade a toxic contaminant, Rhodamine B (RDMB). Furthermore, CuCoNC+Oxone has a smaller activation energy for RDMB elimination and maintains its superior effectiveness for removing RDMB in various water conditions. The computational chemistry insights have revealed the RDMB degradation mechanism. This study reveals that CuCoNC is a useful activator for Oxone to eliminate RDMB.

Hollow-architected Co3O4 for enhancing Oxone activation to eliminate an anesthetic, benzocaine, from water: A structure-property investigation with degradation pathway and eco-toxicity

Hollow-architected Co3O4 for enhancing Oxone activation to eliminate an anesthetic, benzocaine, from water: A structure-property investigation with degradation pathway and eco-toxicity

Modulating Direct Growth of Copper Cobaltite Nanostructure on Copper Mesh as a Hierarchical Catalyst of Oxone Activation for Efficient Elimination of Azo Toxicant.

As cobalt (Co) has been the most useful element for activating Oxone to generate SO4•-, this study aims to develop a hierarchical catalyst with nanoscale functionality and macroscale convenience by decorating nanoscale Co-based oxides on macroscale supports. Specifically, a facile protocol is proposed by utilizing Cu mesh itself as a Cu source for fabricating CuCo2O4 on Cu mesh. By changing the dosages of the Co precursor and carbamide, various nanostructures of CuCo2O4 grown on a Cu mesh can be afforded, including nanoscale needles, flowers, and sheets. Even though the Cu mesh itself can be also transformed to a Cu-Oxide mesh, the growth of CuCo2O4 on the Cu mesh significantly improves its physical, chemical, and electrochemical properties, making these CuCo2O4@Cu meshes much more superior catalysts for activating Oxone to degrade the Azo toxicant, Acid Red 27. More interestingly, the flower-like CuCo2O4@Cu mesh exhibits a higher specific surface area and more superior electrochemical performance, enabling the flower-like CuCo2O4@Cu mesh to show the highest catalytic activity for Oxone activation to degrade Acid Red 27. The flower-like CuCo2O4@Cu mesh also exhibits a much lower Ea of Acid Red 27 degradation than the reported catalysts. These results demonstrate that CuCo2O4@Cu meshes are advantageous heterogeneous catalysts for Oxone activation, and especially, the flower-like CuCo2O4@Cu mesh appears as the most effective CuCo2O4@Cu mesh to eliminate the toxic Acid Red 27.

Templating agent-mediated Cobalt oxide encapsulated in Mesoporous silica as an efficient oxone activator for elimination of toxic anionic azo dye in water: Mechanistic and DFT-assisted investigations

While Azorubin S (AZRS) is extensively used as a reddish anionic azo dye for textiles and an alimentary colorant in food, AZRS is mutagenic/carcinogenic, and it shall be removed from dye-containing wastewaters. In view of advantages of SO4•--related chemical oxidation technology, oxone (KHSO5) would an ideal source of SO4•- for degrading AZRS, and heterogeneous Co3O4-based catalysts is required and shall be developed for activating oxone. Herein, a facile protocol is proposed for fabricating mesoporous silica (MS)-confined Co3O4 by a templating agent-mediated dry-grinding procedure. As the templating agent retained inside the ordered pores of MS (before calcination) would facilitate insertion and dispersion of Co ions into pores, the resulting Co3O4 nanoparticles (NPs) would be grown and confined within the pores of MS after calcination, affording Co@MS. On the contrary, another analogue, Co/MS, is also prepared using the similar protocol without the templating agent-mediated introduction of Co, but Co3O4 NPs seriously aggregate as clusters on MS. Therefore, Co@MS outperforms Co/MS for activating oxone to eliminate AZRS. Co@MS shows a noticeably lower activation energy of AZRS elimination than the existing catalysts, revealing its advantage over the reported catalysts. Moreover, the mechanistic investigation of AZRS elimination by Co@MS-activated oxone has been also elucidated for identifying the presence of SO4•‒, •OH, and 1O2 in AZRS degradation using scavengers, electron paramagnetic resonance spectroscopy, and semi-quantification. The AZRS decomposition pathway is also investigated and unveiled in details via the DFT calculation. These results validate that Co@MS appears as a superior catalyst of oxone activation for AZRS degradation.

Ambient-Visible-Light-Mediated Enhanced Degradation of UV Stabilizer Bis(4-hydroxyphenyl)methanone by Nanosheet-Assembled Cobalt Titanium Oxide: A Comparative and DFT-Assisted Investigation

Bis(4-hydroxyphenyl)methanone (BHPM), a common ultraviolet stabilizer and filter (USF), is extensively added in sunscreens; however, BHPM is proven as an endocrine disruptor, posing a serious threat to aquatic ecology, and BHPM should be then removed. As sulfate radical (SO4•−) could be useful for eliminating emerging contaminants, oxone appears as a favorable source reagent of SO4•− for degrading BHPM. Even though cobalt is a useful catalyst for activating oxone to generate SO4•−, it would be even more promising to utilize ambient-visible-light irradiation to enhance oxone activation using cobaltic catalysts. Therefore, in contrast to the conventional cobalt oxide, cobalt titanium oxide (CTO) was investigated for chemical and photocatalytic activation of oxone to eliminate BHPM from water. Especially, a special morphology of nanosheet-assembled configuration of CTO was designed to maximize active surfaces and sites of CTO. Thus, CTO outperforms Co3O4 and TiO2 in degrading BHPM via oxone activation. Furthermore, the substituent of Ti enabled CTO to enhance absorption of visible light and possessed a much smaller Eg. These photocatalytic properties intensified CTO’s activity for oxone activation. CTO possessed a significantly smaller Ea of degradation of USFs than other catalytic systems. Mechanistic insight for degrading BHPM by CTO + oxone was explicated for identifying contribution of reactive oxygen species to BHPM degradation. The BHPM degradation pathway was also investigated and unveiled in details via the DFT calculation. These results validated that CTO is a superior cobaltic alternative for activating oxone to eliminate BHPM.

MOF-templated hollow cobalt sulfide as an enhanced Oxone activator for degradation of UV Absorber: Key role of sulfur Vacancy-Induced highly active CoII sites

• Single-step sulfidation allows hollow rhombic cobalt sulfide (HRCS) to possess defects and SV. • HRCS exhibits excellent Oxone activation for Novantisol (NVT) degradation dominated by SO 4 •−. • SV-induced highly active Co II accounts for high SO 4 •− generation enhanced by S species. • O 2 •− -mediated 1 O 2 generation is fully explored. • Pathways for NVT degradation is unraveled elaborately via DFT calculation. This study aimed to design hollow rhombic cobalt sulfide (HRCS) via a single-step sulfidation of cobaltic metal organic framework (CoMOF) as a template. The obtained HRCS with abundance of defects and sulfur vacancy (SV) was then employed for degradation of Novantisol (NVT), a sunscreen agent, through Oxone activation. The superior catalytic performance of HRCS was attributed to its more electroactive sites and low charge transfer resistance that were enhanced by highly active Co II due to the existence of SV for increased generation of SO 4 •− as a predominant species. Although • OH and 1 O 2 were proved to be generated obviously from activation of Oxone over HRCS, their contribution to NVT degradation was marginal. While • OH and SO 4 •− were generated mainly by Co II -activated Oxone, the formation of SO 4 •− was accelerated by sulfur species and the disproportionation of SO 5 •− . The limited conversion of SO 4 •− by reacting with − OH and undirect self-hydrolysis of Oxone, on the other hand, contributed to enhanced • OH generation. Further experiments on furfuryl alcohol (FFA) consumption showed that 1 O 2 generated from O 2 •− as an intermediate species did not account for the NVT degradation but rather from self-decomposition of Oxone, dissociation and self-combination of SO 5 •− , and disproportionation of • OH. The degradation pathway was also investigated and unveiled in details via DFT calculation, which further validated that HRCS appeared to be a superior catalyst for NVT degradation through Oxone activation.

Study on the synthesis and characterization of CoTiO3 catalysts and their catalytic properties in Oxone activation for the degradation of tetracycline antibiotic in water

The chemical degradation of sulfate by activated Oxyone has the advantages of high degradation capacity, wide pH range and convenient transportation and storage, making it one of the most attractive advanced oxidation processes (AOPs). Besides, Co is the metal most capable of activating Oxone to produce sulfate. Therefore, it is critical to develop Co-based catalyst, an effective and recyclable heterogeneous catalyst, for activating Oxone to degrade tetracycline. In this study, CoTiO3 was extensively investigated for the activation of Oxone to generate sulfate radicals and degrade tetracycline antibiotics. The results showed that more than 95% of tetracyclines could be degraded at the amount of CoTiO3 catalyst of 0.02 g, the Oxone reagent concentration of 0.4 mmol l−1, and the pH value of 7. The removal rate of tetracyclines could still reach more than 85% after the CoTiO3 composite was repeatedly used for four consecutive cycles. These results indicate that CoTiO3/Oxone can be explored as an effective system for degrading long-lived organic pollutants.

Fe-Mn Bimetallic Oxide-Enabled Facile Cleaning of Microfiltration Ceramic Membranes for Effluent Organic Matter Fouling Mitigation via Activation of Oxone

Fe-Mn Bimetallic Oxide-Enabled Facile Cleaning of Microfiltration Ceramic Membranes for Effluent Organic Matter Fouling Mitigation via Activation of Oxone

Hybrid metal and non-metal activation of Oxone by magnetite nanostructures co-immobilized with nano-carbon black to degrade tetracycline: Fenton and electrochemical enhancement with bio-assay

Electrochemically synthesized magnetite nanostructures (ESMNPs) as a metal activator and nano-carbon black (NCB) as a non-metal activator were co-immobilized by alginate natural polymer to activate Oxone for the degradation of tetracycline (TC) antibiotic. The formation of sulfate radical was indirectly confirmed during the Oxone/ESMNPs/NCB/alginate process via the addition of scavenging compounds. This study revealed the high reusability potential of the ESMNPs/NCB/alginate with a negligible decrease in the degradation rate from 5.7 × 10−2 to 4.9 × 10−2 min−1 after four experimental runs. The release of iron ions into the effluent did not violate its discharge standard, indicating high stability of the catalyst due to the co-immobilization. The enhanced degradation rate of 6.7 × 10−2 min−1 was observed under basic conditions. Both Fenton (7.9 × 10−2 min−1) and electrochemical (7.7 × 10−2 min−1) processes improved the degradation effectiveness at hydrogen peroxide concentration of 30 mM and current density of 100 mA, respectively. Response surface methodological optimization of the bio-assessment was also performed. Accordingly, the optimized TC concentration of 68 mg/L, Oxone concentration of 1.6 mM and exposure time of 60 min resulted in the minimum inhibition percent (%) of 15.8%. Confirmatory real experiments demonstrated the results of numerical optimization. Possible degradation pathways along with the ECOSAR-based bioassay of the intermediates were also proposed.

Enhanced degradation of ultra-violet stabilizer Bis(4-hydroxy)benzophenone using oxone catalyzed by hexagonal nanoplate-assembled CoS 3-dimensional cluster

As UV-light stabilizers, Bis(4-hydroxy)benzophenone (BBP), are extensively consumed to quench radicals from photooxidation, continuous release of BPs into the environment poses serious threats to the ecology in view of their xenohormone toxicities, and BBP shall be eliminated from water to avoid its adverse effect. Since sulfate radical (SR)-based chemical oxidation techniques have been proven as effective procedures for eliminating organic emerging contaminants, this study aims to develop useful SR-based procedures through activating Oxone for degrading BBP in water. In contrast to the conventional Co3O4, cobalt sulfide (CoS) is particularly proposed as an alternative heterogeneous catalyst for activating Oxone to degrade BBP because CoS exhibits more reactive redox characteristics. As structures of catalysts predominantly control their catalytic activities, in this study, a unique nanoplate-assembled CoS (NPCS) 3D cluster is fabricated via a convenient one-step process to serve as a promising heterogeneous catalyst for activating Oxone to degrade BBP. With NPCS=100mg/L and Oxone=200mg/L, 5mg/L of BBP can be completely eliminated in 60min. The catalytic activity of NPCS towards Oxone activation also significantly surpasses the reference material, Co3O4, to enhance degradation of BBP. Ea of BBP degradation by NPCS-activated Oxone is also determined as a relatively low value of 42.7kJ/mol. The activation mechanism as well as degradation pathway of BBP degradation by NPCS-activated Oxone was investigated and validated through experimental evidences and density functional theory (DFT) calculation to offer valuable insights into degradation behaviors for developing SR-based processes of BBP degradation using CoS catalysts.

Metal-complexed covalent organic frameworks derived N-doped carbon nanobubble–embedded cobalt nanoparticle as a magnetic and efficient catalyst for oxone activation

While Cobalt nanoparticles (Co NPs) are useful for catalytic Oxone activation, it is more advantageous to embed/immobilize Co NPs on nitrogen-doped carbon substrates to provide synergy for enhancing catalytic performance. Herein, this study proposes to fabricate such a composite by utilizing covalent organic frameworks (COF) as a precursor. Through complexation of COF with Co, a stable product of Co-complexed COF (Co-COF) can be synthesized. This Co-COF is further converted through pyrolysis to N-doped carbon in which cobaltic NPs are embedded. Owing to its well-defined structures of Co-COF, the pyrolysis process transforms COF into N-doped carbon with a bubble-like morphology. Such Co NP-embedded N-doped carbon nanobubbles (CoCNB) with pores, magnetism and Co, shall be a promising catalyst. Thus, CoCNB shows a much stronger catalytic activity than commercial Co3O4 NPs to activate Oxone to degrade toxic Amaranth dye (AMD). CoCNB-activated Oxone also achieves a significantly lower Ea value of AMD degradation (i.e., 27.9kJ/mol) than reported Ea values in previous literatures. Besides, CoCNB is still effective for complete elimination of AMD in the presence of high-concentration NaCl and surfactants, and CoCNB is also reusable over five consecutive cycles.

S-doped TiO2 photocatalyst for visible LED mediated oxone activation: Kinetics and mechanism study for the photocatalytic degradation of pyrimethanil fungicide

• ST photocatalyst was synthesized and exerted optimal performance at S/Ti molar ratio of 0.25. • The ST/Oxone/Vis LED process was demonstrated in the PYR photodegradation and proven efficient at pH ranged from 2.9 to 8.1. • SO 4 •- , • OH, 1 O 2 , O 2 •- , and h + were identified as the reactive species involved in ST/Oxone/Vis LED process. • Chloride and humic acid exhibited positive effect on ST/Oxone/Vis LED process. • PYR was degraded via four major pathways and mineralized to H 2 O and CO 2 . The degradation of pyrimethanil (PYR) was investigated through the activation of oxone by the S-TiO 2 (ST) photocatalyst under visible LED irradiation. The catalyst characterization revealed that the sulfur doping mechanism was based on the cation (S 6+ ) substitution of Ti 4+ in TiO 2 lattice. The optimal molar ratio of S/Ti at 0.25 was proven efficient in the PYR degradation. Influences of various reaction parameters including ST loading, oxone dosage, PYR concentration, and initial solution pH were examined. SO 4 •- , • OH, 1 O 2 , O 2 •- , and h + were found to be the reactive species generated in the ST/Oxone/Vis LED process. Different natural water constituents exerted dissimilar effects because of the generation of additional reactive species or their radical scavenging capabilities. Moreover, the reusability test indicates the ST photocatalyst is reusable and stable. A series of degradation intermediates was detected via four major degradation pathways. Overall, the ST/Oxone/Vis LED process was demonstrated to be a promising approach for the removal of organic pollutants.

Oxone activation by UVA-irradiated FeIII-NTA complex: Efficacy, radicals formation and mechanism on crotamiton degradation

Abstract This study demonstrated an efficient activation of Oxone by ultraviolet light A-irradiated FeIII-nitrilotriacetate complex to induce the generation of sulfate and hydroxyl radicals (i.e., SO4•− and HO•) under initial neutral pH. The important parameters such as the solution pH, the molar ratio of nitrilotriacetate:FeIII, the dosages of Oxone and FeIII-nitrilotriacetate complex were evaluated in terms of the degradation kinetics of an emerging contaminant Crotamiton. The results indicated that fast degradation rates of crotamiton were achieved under initial circumneutral conditions (e.g., pH 5.0–7.0), with apparent rate constants at 0.0936–0.1287 min−1 (the ultraviolet light fluence-based rate constants at 0.48–0.66 J−1 cm2). In addition, the optimal molar ratio of nitrilotriacetate:FeIII was determined as 1:1, larger ratios decreased the degradation rate of crotamiton due to the competition effect of nitrilotriacetate on SO4•−. The suitable dosages of Oxone and FeIII-nitrilotriacetate complex were determined as 0.5 mM and 0.1 mM, respectively. Under the given optimal conditions, more than 99% degradation efficiency of crotamiton was achieved at an ultraviolet light fluence of 3.90 J cm−2, better than those results obtained by the activation of S2O82− and H2O2. The results of quenching tests (tert-butyl alcohol and 2-propanol as scavengers) suggested that SO4•− and HO• contributed ~65% and 35% to the degradation of crotamiton, respectively. Furthermore, the identified intermediates includes hydroxy-crotamiton, dihydroxy-crotamiton, aldehyde-crotamiton, aldehyde-dihydroxy-crotamiton, N-ethyl-2,3-dihydroxy-N-(o-tolyl)butanamide, (E)-N-ethyl-N-phenylbut-2-enamide, 2-(ethylamino)benzaldehyde and/or 2-(o-tolylamino)acetaldehyde, and (E)-N-ethylbut-2-enamide. The results indicated that the SO4•− preferentially attacked on the amide and methyl groups of crotamiton. This work provided insight into the efficacy, radicals formation and mechanism on the activation of Oxone by ultraviolet light A-irradiated FeIII-nitrilotriacetate complex, offering an alternative approach for advanced water treatment.

Co3O4 nanocube-decorated nitrogen-doped carbon foam as an enhanced 3-dimensional hierarchical catalyst for activating Oxone to degrade sulfosalicylic acid

As sulfosalicylic acid (SUA) is extensively used as a pharmaceutical product, discharge of SUA into the environment becomes an emerging environmental issue because of its low bio-degradability. Thus, SO4--based advanced oxidation processes have been proposed for degrading SUA because of many advantages of SO4-. As Oxone represents a dominant reagent for producing SO4-, and Co is the most capable metal for activating Oxone to generate SO4-, it is critical to develop an effective but easy-to-use Co-based catalysts for Oxone activation to degrade SUA. Herein, a 3D hierarchical catalyst is specially created by decorating Co3O4 nanocubes (NCs) on macroscale nitrogen-doped carbon form (NCF). This Co3O4-decorated NCF (CONCF) is free-standing, macroscale and even squeezable to exhibit interesting and versatile features. More importantly, CONCF consists of Co3O4 NCs evenly distributed on NCF without aggregation. The NCF not only serves as a support for Co3O4 NCs but also offers additional active sites to synergistically enhance catalytic activities towards Oxone activation. Therefore, CONCF exhibits a higher catalytic activity than the conventional Co3O4 nanoparticles for activating Oxone to fully eliminate SUA in 30min with a rate constant of 0.142min-1. CONCF exhibits a much lower Ea value of SUA degradation (35.2kJ/mol) than reported values, and stable catalytic activities over multi-cyclic degradation of SUA. The mechanism of SUA degradation is also explored, and degradation intermediates of SUA degradation are identified to provide a possible pathway of SUA degradation. These features validate that CONCF is certainly a promising 3D hierarchical catalyst for enhanced Oxone activation to degrade SUA. The findings obtained here are also insightful to develop efficient heterogeneous Oxone-activating catalysts for eliminating emerging contaminants.

Efficient activation of oxone by pyrite for the degradation of propanil: Kinetics and degradation pathway

Pyrite (FeS2) is an abundant sulfide-associated iron mineral that exists in the earth. In this study, the pyrite/oxone process was demonstrated to be an effective approach for the catalytic degradation of propanil, where more than 90% decay ([propanil]0 = 0.01 mM) was achieved within 15 min. Typically, the effects of various experimental parameters, including catalyst loading, oxone dosage, propanil concentration, and initial solution pH, were examined. Two optimal reaction pH values were observed at pH 9.1 and pH 2.9. The generated SO4－ and OH were verified to be the dominant reactive radicals and primarily responsible for the propanil degradation. Both Fe(II) regeneration and sulfur conversion play an important role in oxone activation mechanism and effectively aid the catalytic activity of pyrite. Different co-existing natural water constituents exert dissimilar effects on the pyrite/oxone process. Additionally, the reusability test of pyrite exhibited a reasonable catalytic activity. The pyrite/oxone process was proven efficient in terms of propanil mineralization. A series of reaction intermediates was detected via four major degradation pathways. Overall, the pyrite/oxone process could be a promising approach for the removal of organic compounds in water.

Porous hexagonal nanoplate cobalt oxide derived from a coordination polymer as an effective catalyst for activating Oxone in water

As cobalt (Co) represents an effective transition metal for activating Oxone to degrade contaminants, tricobalt tetraoxide (Co3O4) is extensively employed as a heterogeneous phase of Co for Oxone activation. Since Co3O4 can be manipulated to exhibit various shapes, 2-dimensional plate-like morphology of Co3O4 can offer large contact surfaces. If the large plate-like surfaces can be even porous, forming porous nanoplate Co3O4 (PNC), such a PNC should be a promising catalyst for Oxone activation. Therefore, a facile but straightforward method is proposed to prepare such a PNC for activating Oxone to degrade pollutants. In particular, a cobaltic coordination polymer with a morphology of hexagonal nanoplate, which is synthesized through coordination between Co2+ and thiocyanuric acid (TCA), is adopted as a precursor. Through calcination, CoTCA could be transformed into hexagonal nanoplate-like Co3O4 with pores to become PNC. This PNC also shows different characteristics from the commercial Co3O4 nanoparticle (NP) in terms of surficial reactivity and textural properties. Thus, PNC exhibits a much higher catalytic activity than the commercial Co3O4 NP towards activation of Oxone to degrade a model contaminant, salicylic acid (SA). Specifically, SA was 100% degraded by PNC activating Oxone within 120min, and the Ea of SA degradation by PNC-activated Oxone is 70.2kJ/mol. PNC can also remain stable and effective for SA degradation even in the presence of other anions, and PNC could be reused over multiple cycles without significant loss of catalytic activity. These features validate that PNC is a promising and useful Co-based catalyst for Oxone activation.

Mesoporous rGO@ZnO composite: Facile synthesis and excellent water treatment performance by pesticide adsorption and catalytic oxidative dye degradation

This study describes the facile fabrication, characterization and applications of mesoporous reduced graphene [email protected] oxide ([email protected]) composite for the adsorptive removal of the toxic organophosphorus pesticide chlorpyrifos (CPF) and catalytic oxidative degradation of the crystal violet (CV) dye from their respective aqueous solutions. The physical properties of the as-synthesized composite were evaluated by various state of the art techniques like powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared (FT-IR) spectroscopy. The adsorption efficacy of the [email protected] composite was evaluated by conducting adsorption isotherm studies, kinetics studies and thermodynamic studies. The effect of solution pH, adsorbent dosage, solvent polarity, contact time and regeneration ability of the adsorbent on the adsorptive removal efficiency were also studied. Excellent removal efficiency of 95.4% was achieved within 70 min of contact time with the [email protected] composite and more than 75% of the pesticide was adsorbed at the end of the fifth adsorption cycle. Batch adsorption results fitted well with the Freundlich adsorption isotherm with a high coefficient of determination (R2). The adsorption kinetics was best described by a pseudo-second-order model with an R2 value of 0.93. Thermodynamic parameters corroborate the physisorption nature of the adsorption owing to the spontaneous and exothermic adsorption process. Pesticide contaminated water was used to determine the field applicability of the [email protected] composite. The catalytic efficiency was evaluated by the oxidative dye degradation performance of [email protected] based on the activation of oxone to produce sulfate radicals which degraded the CV dye within 30 min. Results indicate that mesoporous [email protected] is an excellent candidate and possesses huge potential in water treatment.