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Excessive consumption of energy and resources is a major challenge in wastewater treatment. Here, a novel heterogeneous Fenton-like catalyst consisting of Cu-doped graphene-like catalysts (Cu-GCD NSs) was first synthesized by an enhanced carbothermal reduction of β-cyclodextrin (β-CD). The catalyst exhibits excellent Fenton-like catalytic activity for the degradation of various pollutants under neutral conditions, accompanied by low H 2 O 2 consumption. The results of structural characterization and theoretical calculations confirmed that the dual reaction centers (DRCs) were constructed on Cu-GCD NSs surface through C-O-Cu bonds supported on zero-valent copper species, which play a significant role in the high-performance Fenton-like reaction. The pollutants that served as electron donors were decomposed in the electron-poor carbon centers, whereas H 2 O 2 and dissolved oxygen obtained these electrons in the electron-rich Cu centers through C-O-Cu bonds, thereby producing more active species. This study demonstrates that the electrons of pollutants can be efficiently utilized in Fenton-like reactions by DRCs on the catalyst surface, which provides an effective strategy to improve Fenton-like reactivity and reduce H 2 O 2 consumption. [Display omitted] [ABSTRACT FROM AUTHOR]

High energy consumption is impedimental for eliminating refractory organics in wastewater by current technologies. Herein, we develop an efficient self-purification process for actual non-biodegradable dyeing wastewater at pilot scale, using N-doped graphene-like (CN) complexed Cu-Al 2 O 3 supported Al 2 O 3 ceramics (HCLL-S8-M) fixed-bed reactor without additional input. About 36% chemical oxygen demand removal was achieved within 20 min empty bed retention time and maintained stability for almost one year. The HCLL-S8-M structure feature and its interface on microbial community structure, functions, and metabolic pathways were analyzed by density-functional theory calculation, X-ray photoelectron spectroscopy, multiomics analysis of metagenome, macrotranscriptome and macroproteome. On the surface of HCLL-S8-M, a strong microelectronic field (MEF) was formed by the electron-rich/poor area due to Cu-π interaction from the complexation between phenolic hydroxy of CN and Cu species, driving the electrons of the adsorbed dye pollutants to the microorganisms through extracellular polymeric substance and the direct transfer of extracellular electrons, causing their degradation into CO 2 and intermediates, which was degraded partly via intracellular metabolism. The lower energy feeding for the microbiome produced less adenosine triphosphate, resulting in little sludge throughout reaction. The MEF from electronic polarization is greatly potential to develop low-energy wastewater treatment technology. [Display omitted] • An efficient pilot-scale self-purification process for actual dyeing wastewater was developed. • The COD of dyeing wastewater was effectively removed and maintained stability for one year. • The superior performance was attributed to surface microelectric fields (MEF). • The MEF drived the electrons of the adsorbed pollutants to the microorganisms. • The adsorbed-dyes electrons were transferred though EPS and direct extracellular transfer. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Mo S C and Mo O Co electron transfer bridges are successfully constructed on CMS-rGO NSs. • CMS-rGO NSs possesses the function of generating and activating H 2 O 2 synchronously. • CMS-rGO NSs shows very high Fenton-like activity for degradation of pollutants. • Dye pollutants can directly act as electron donors for CMS-rGO NSs. Abstract Consumption of additional H 2 O 2 is necessary in classical Fenton catalysis. Herein, we report a novel and special nanocatalyst consisting of CoMoS 2 nanosphere-embedded, reduced graphene oxide (rGO) nanosheets (CMS-rGO NSs). This nanocatalyst was discovered to have an impressive reactivity for in situ generation and synchronistical activation of H 2 O 2 in different active centers, yielding fast and efficient degradation of the pollutants. The reaction rate is ∼21 times higher than that of conventional Fenton catalysts. The characterization shows that countless flower-like CoMoS 2 nanospheres are uniformly embedded in the rGO nanosheets through Mo S C bonding bridges in CMS-rGO NSs, which leads to activation of the π electrons and their transfer from rGO to the metal centers (π → M). The formed Mo O Co further leads to a distribution of orientations of the electrons around the metal centers due to the different electronegativity of Mo and Co. During the reaction, the dissolved O 2 is efficiently reduced to HO 2 /O 2 − around the electron-rich Mo center, and HO 2 /O 2 − is further reduced to H 2 O 2 around the Co center. The generated H 2 O 2 is finally reduced to OH for degrading dyes in the electron-rich metal (Mo or Co) centers of CMS-rGO NSs. The dye pollutants also act as electron donors, and they are directly degraded in the electron-poor π-center of CMS-rGO NSs, which promote the electron transfer cycle and achieve electron gain-loss balance. This discovery provides a new strategy for H 2 O 2 generation-activation and pollutant degradation through constructing electron transfer bridges over the surface of catalysts. [ABSTRACT FROM AUTHOR]

A novel self-sustaining monolithic photoelectrocatalytic/photovoltaic (SMPP) system is constructed with a FTO-glass-based WO 3 /BiVO 4 photoanode, which was prepared by coating BiVO 4 on WO 3 nanoplate array using simple wet chemical methods, a rear Si photovoltaic cell (PVC) and a counter Pt-black/Pt cathode. The optimum SMPP system shows an efficient and stable degradation of tetracycline hydrochloride with a rate constant 0.75 h −1 , and yields an open circuit voltage 1.35 V, a short circuit current 2900 μA cm −2 , a power density 1112 μW cm −2 , which is nearly 14 times that of theultimate conventional photocatalytic fuel cell to date, and a hydrogen generation rate 52.6 μmol h −1 cm −2 . This outstanding performance should be due to the efficient electron/hole separation and light exploitation, because, under stimulated sunlight illumination, the front WO 3 /BiVO 4 photoanode absorbs short-wavelength photons and generates electron/hole pairs, in which the photogenerated holes can oxidize organics, while the rear Si PVC captures the transmitting longer-wavelength photons to generate photovoltage that drives photogenerated electrons to the cathode for reducing H + to H 2 and generating electricity in the external-circuit. The results also demonstrate that various refractory organics can be efficiently decomposed along with the production of electricity and hydrogen by the SMPP system. This work provides a more efficient way to dispose organics and simultaneously produce clean energy than conventional technologies and serves well as a promising technology for wastewater recycling. [ABSTRACT FROM AUTHOR]

Metal-containing Fenton catalysts have been widely investigated. Here, we report for the first time a highly effective stable metal-free Fenton-like catalyst with dual reaction centers consisting of 4-phenoxyphenol-functionalized reduced graphene oxide nanosheets (POP-rGO NSs) prepared through surface complexation and copolymerization. Experimental and theoretical studies verified that dual reaction centers are formed on the C-O-C bridge of POP-rGO NSs. The electron-rich center around O is responsible for the efficient reduction of H2O2 to •OH, while the electron-poor center around C captures electrons from the adsorbed pollutants and diverts them to the electron-rich area via the C-O-C bridge. By these processes, pollutants are degraded and mineralized quickly in a wide pH range, and a higher H2O2 utilization efficiency is achieved. Our findings address the problems of the classical Fenton reaction and are useful for the development of efficient Fenton-like catalysts using organic polymers for different fields. [ABSTRACT FROM AUTHOR]

[Display omitted] • Surface microelectric fields (SMEF) on catalyst were formed by electrostatic force. • The formation of SMEF maximize the removal of refractory pollutants in wastewater. • The SMEF can link electron transfer between refractory pollutants and microorganisms. • The interspecific electron transport was induced by SMEF to can speed up degradation. The stable structure and toxic effect of refractory organic pollutants in wastewater lead to the problem of high energy consumption in water treatment technology. Herein, we propose a synergistic purification of refractory wastewater driven by microorganisms and surface microelectric fields (SMEF) over a dual-reaction-center (DRC) catalyst HCLL-S8-M prepared by an in situ growth method of carbon nitride on the Cu-Al 2 O 3 surface. Characterization techniques demonstrate the successful construction of SMEF with strong electrostatic force over HCLL-S8-M based on cation-π interactions between metal copper ions and carbon nitride rings. With the catalyst as the core filler, an innovative fixed bed bioreactor is constructed to purify the actual kitchen-oil wastewater. The removal efficiency of the wastewater even with a very low biodegradability (BOD 5 /COD = 0.33) can reach 60% after passing through this bioreactor. An innovative reaction mechanism is revealed for the first time that under the condition of a small amount of biodegradable organic matter, the SMEF induces the enrichment of electric active microorganisms (Desulfobulbus and Geobacter) in the wastewater, accelerates the interspecies electron transfer of intertrophic metabolism with the biodegradable bacteria through the extracellular electron transfer mechanism such as cytochrome C and self-secreted electron shuttle. The electrons of the refractory organic pollutants adsorbed on the surface of the catalyst are delocalized by the SMEF, which can be directly utilized by microorganisms through EPS conduction. The SMEF generated by electron polarization can maximize the utilization of pollutants and microorganisms in wastewater and further enhance degradation without adding any external energy, which is of great significance to the development of water self-purification technology. [ABSTRACT FROM AUTHOR]

A twofold cation-π-assembled catalyst consisting of honeycomb microsphere-like MoS 2 cross-linking g-C 3 N 4 hybrid (HM-MS/CN) is first developed to address the bottleneck of excessive resource and energy consumption in Fenton chemistry. A series of modern characterization techniques combined with theoretical calculation are used to reveal and verify the twofold cation-π interaction (Mo-O-C and Mo-S-C bonding bridges). It is found that the electrons of pollutants can be captured by H 2 O 2 and O 2 through the twofold cation-π interaction during Fenton-like reaction, which inhibits the oxidative decomposition of H 2 O 2 and promotes its hydroxylation. As a result, HM-MS/CN shows excellent performance for water purification by initiating pollutants as electron donors substituting H 2 O 2 consumption under mild natural conditions, and the actual consumption of H 2 O 2 in this system is only 6–8% of that in the common Fenton systems. This discovery is of great significance for the development of novel water purification technology with high efficiency and low consumption. [Display omitted] • A twofold cation-π-assembled catalyst consisting of HM-MS/CN is first prepared. • HM-MS/CN shows excellent performance for actual water purification. • The actual consumption of H 2 O 2 is only 6–8% of that in the common Fenton systems. • Twofold cation-π interaction based on Mo-O-C and Mo-S-C is responsible for excellent performance. • Pollutants act as electron donors substituting H 2 O 2 consumption via twofold cation-π. [ABSTRACT FROM AUTHOR]

Solid solution of BiOBr and BHO (BiO(OH) 0.06 Br 0.94 ) with abundant oxygen vacancies was supported on Ag/AgBr using precipitation and deposition–precipitation methods. The photocatalyst showed high and stable photocatalytic activity for the degradation of chlorophenols and azodyes in water under visible to NIR light irradiation without any release of Ag + , which came from visible-excited AgBr and the SPR of Ag NPs in the visible and NIR region. The different interfacial charge-transfer processes were verified on the basis of cyclic voltammetry analyses and all experimental information. The conduction band (CB) electrons of photoexcited AgBr reacted with the adsorbed oxygen forming O 2 •− , while the valence band (VB) holes of AgBr were transported the VB of BiO(OH) 0.06 Br 0.94 to oxidize organic pollutants or H 2 O to • OH. The plasmon-induced electrons from Ag NPs transferred to the CB of AgBr reacting with the adsorbed oxygen to O 2 •− , while the electrons trapped on the oxygen vacancies of BiO(OH) 0.06 Br 0.94 transferred to Ag NPs recombining with the plasmon-induced holes, inhibiting the release of Ag + , and the resulted VB holes of BiO(OH) 0.06 Br 0.94 oxidized organic compound. These interfacial charge transfers evidenced the high photoactivity and photostability of BiO(OH) 0.06 Br 0.94 /Ag/AgBr. [ABSTRACT FROM AUTHOR]

Cu-doped BiO x composites were prepared with and without citric acid. In the presence of citric acid, Bi 0 and Cu 2+ /Cu + were confirmed to coexist in the composite (BiCu9/Bi 0 ) by X-ray diffraction and X-ray photoelectron spectroscopy. The catalyst showed high Fenton activity and stability for the degradation and mineralization of 2-chlorophenol in the pH range of 6–8. H 2 O 2 was predominately converted into OH radicals in BiCu9/Bi 0 suspension, as assessed by the electron spin resonance technique. In the composite, Bi 0 inhibited the oxidation of H 2 O 2 by Cu 2+ into O 2 and OH by reducing Cu 2+ , enhancing the reaction of H 2 O 2 with Cu + to produce OH. Intermediate determination showed that 2-chlorophenol was decomposed mainly by OH radicals into hydroxylation products, subsequently decomposed into short-chain organic acids, and eventually decomposed into CO 2 and H 2 O. [ABSTRACT FROM AUTHOR]

Copper-doped mesoporous silica microspheres (Cu-MSMs) with the coexistence of Cu(I) and Cu(II) were prepared using a hydrothermal process and characterized by several methods. The characterization studies suggested that 0.91 wt% of the copper species could exist in the framework of the mesoporous silica microspheres by chemical binding of Si O Cu; excess copper species were located in the extraframework sites, leading to more oxygen vacancies on the surface of the catalysts. The framework Cu of Cu-MSMs was found to be highly effective and stable for the degradation of pharmaceutical pollutants, as demonstrated with phenytoin, ibuprofen and diphenhydramine in the presence of H 2 O 2 at neutral pH values. The conversion of the three pharmaceuticals could reach 100% within 75, 120 and 90 min, respectively; the leaching of Cu was much lower than the EU directives and USA regulations. By the studies of electron spin resonance, gas chromatography–mass spectrometry, Fourier-transform infrared spectra, in situ Raman spectra and X-ray photoelectron spectroscopy, an interaction process among the framework Cu of Cu-MSMs, pharmaceuticals and H 2 O 2 was proposed: During the Fenton-like reaction, the framework Cu(I) in Cu-MSMs primarily converted H 2 O 2 into OH, and Cu(I) was oxidized to Cu(II) by H 2 O 2 . The pharmaceuticals were attacked by OH to form phenolic intermediates, adsorbing on the surface of Cu-MSMs, complexing with the framework Cu(II), forming Cu-ligands. Cu-ligands interacted with H 2 O 2 and enhanced the reduction rate of Cu(II), resulting in the more Cu(I) production; consequently, accelerated the Cu(II)/Cu(I) cycles on the catalyst surface, leading to more OH generation for the pharmaceuticals oxidation. [ABSTRACT FROM AUTHOR]

• The Fenton-like Cu-PAN 3 catalysts is first synthesized by co-precipitation and carbon thermal reduction method. • Dual reaction centers are constructed around graphene-like carbon and Cu species. • The pollutants as electron donors inhibit the ineffective decomposition of H 2 O 2 at the electron-poor centers. • The pollutant removal mainly relies on the surface cleavage at the electron-poor centers. High energy consumption has seriously hindered the development of Fenton-like reactions for the removal of refractory organic pollutants in water. To solve this problem, we designed a novel Fenton-like catalyst (Cu-PAN 3) by coprecipitation and carbon thermal reduction. The catalyst exhibits excellent Fenton-like catalytic activity and stability for the degradation of various pollutants with low H 2 O 2 consumption. The experimental results indicate that the dual reaction centers (DRCs) are composed of Cu-N-C and Cu-O-C bridges between copper and graphene-like carbon, which form electron-poor/rich centers on the catalyst surface. H 2 O 2 is mainly reduced at electron-rich Cu centers to free radicals for pollutant degradation. Meanwhile, pollutants can be oxidized by donating electrons to the electron-poor C centers of the catalyst, which inhibits the ineffective decomposition of H 2 O 2 at the electron-poor centers. This therefore significantly reduces the consumption of H 2 O 2 and reduces energy consumption. [Display omitted] [ABSTRACT FROM AUTHOR]

• Co2+-N-C π is constructed via atomically dispersed Co bonding with C-based graphene-like structure. • Co2+-N-C π (Co−π) structure plays key role for PMS activation and pollutant degradation. • Electron donation effect of pollutants is realized through π-π interaction in SACo-NGs system. • High efficiency and low consumption are realized in SACo-NGs/PMS water treatment system. Orbital interaction involving metal cation−π is an important form for electron transfer regulation. To accelerate the interfacial electron transfer of peroxymonosulfate (PMS) activation for water treatment, we report a new strategy through bonding atomically dispersed cobalt with nanospheric C-based graphene-like structures (SACo-NGs) to form metal cation−π structure, driving rapid and directional transfer of the electrons of pollutants to PMS on the catalyst surface. The catalyst SACo-NGs is synthesized by an enhanced hydrothermal-sintering method and the formation of metal cation−π structure is demonstrated by X-ray absorption fine structure (EXAFS), X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance spectroscopy (EPR) and Raman spectroscopy. It is found that Co−π structures (Co2+-N-C π) play a key role for the efficient activation of PMS, which results in pollutants being greatly removed in a few minutes. During the reaction, pollutants can donate electrons for the system through π−π interaction accompanying by the direct oxidative degradation of pollutants. The obtained electrons are quickly transferred to the atomically dispersed cobalt sites through the formed cation−π structure, which promotes the activation of PMS. This is a successful practice in the field of PMS activation using cation−π structure to accelerate electron transfer and achieve rapid degradation of pollutants. [ABSTRACT FROM AUTHOR]

• nZVCu-Cu(II)-rGO is developed via an annealing reduction process for first time. • Nanoscale Cu(0) and Cu(II) are generated on rGO along with C-O-Cu formation. • Dual reaction centers form around Cu(II) and aromatic rings of rGO due to π→Cu. • Nanoscale Cu(0) accelerate the electron transfer of the dual reaction center system. • Pollutants are efficiently degraded by two ways: as electron donors and attacked by radicals. Nanoscale zero-valent copper combined with Cu(II)-doped reduced graphene oxide hybrid (nZVC-Cu(II)-rGO) is synthesized through an annealing reduction process, and it shows very high activity and efficiency for removing refractory organic compounds with H 2 O 2. The conversion rate for the organic pollutant in this system is ∼77 and ∼13 times higher than that in the graphene oxide (GO) and reduced graphene oxide (rGO) systems, respectively. The characterization shows that nanoscale Cu(0) and Cu(II) are generated on the rGO surface during the annealing process and they are accompanied by the C O Cu bonding formation between the rGO substrate and the Cu(II) species in nZVC-Cu(II)-rGO, which induces cation–π interactions on the surface, resulting in the reinforced electron-rich micro-centers formation around the nZVC-enhanced Cu(II) species and electron-poor micro-centers on rGO-aromatic rings. The generation of nanoscale Cu(0) consolidates the polarization of the dual reaction micro-centers and greatly accelerates the electron transfer of the system, thus promoting H 2 O 2 reduction to OH in the electron-rich micro-centers. Pollutants can obviously replace H 2 O 2 as the electron donors of the system and are efficiently oxidized and degraded in the electron-poor micro-centers, with their own electron energy being fully utilized in the nZVC-Cu(II)-rGO Fenton-like system. [ABSTRACT FROM AUTHOR]

BiOI is widely used as photocatalysts for pollutant removal, water splitting, CO 2 reduction and organic transformation due to its excellent photoelectric properties. Here, we report for the first time that a light-free catalyst consisting of the flower-like BiOI microspheres ( f -BiOI MSs) exposing (1 0 1) and (1 1 0) crystal planes prepared by a hydrothermal method in ethylene glycol environment can rapidly eliminate the refractory BPA within only ∼3 min through a Fenton-like process. The reaction activity is ∼190 times higher than that of the conventional Fenton catalyst Fe 2 O 3 . A series of characterizations and experiments reveal the formation of the dual reaction centers on f -BiOI MSs. The electron-rich O centers efficiently reduce H 2 O 2 to OH, while the electron-poor oxygen vacancies capture electrons from the adsorbed pollutants and divert them to the electron-rich area during the Fenton-like reactions. By these processes, pollutants are degraded and mineralized quickly in a wide pH range. Our findings address the problems of the classical Fenton reaction and are useful for the development of efficient Fenton-like catalysts through constructing dual reaction centers. [ABSTRACT FROM AUTHOR]

[Display omitted] • HA was efficiently mineralized in an Fe0-Fe y C z /Fe x -GZIF-8-rGO aqueous suspension. • The polar alkane-alcohol complex was formed with more single electrons on –OH group. • The polar alkane-alcohol complex enhanced its surface cleavage and •OH formation. • The reaction kinetics depends on the surface complex characteristic. Natural organic matter (NOM) has diverse negative impacts on water purification, however, preventing them occurrence very difficult. Herein, humic acid (10 mg/L), as the main component of NOM, is completely destructed within 120 min in the Fe0-Fe y C z /Fe x -GZIF-8-rGO air-saturated aqueous suspension without additional energy input, while its mineralization is followed by three kinetic constants within 480 min. During the process, HA was first complexed with Fe0-Fe y C z /Fe x -GZIF-8-rGO by π-π interaction and H-bonding interaction and cleaved to aromatic compounds and then to alkanes and alcohols with some small acids before 120 min. The electron paramagnetic resonance (EPR) analysis and density functional theory (DFT) calculations confirmed that a strongly polarized alkane-alcohol complex was formed after 150 min with an electron-rich hydroxyl group area in alcohol and an electron-poor alkane area. Moreover, the more electrons of alkane in the complex are delocalized and trapped by O 2 , with the adsorption of the alkane-alcohol complex on the catalyst surface based on the analyses of both electrochemical impedance spectroscopy (EIS) and chronoamperometry, greatly promoting the surface cleavage and hydrolytic process of alkane in the complex and producing more •OH for pollutant degradation than it does from the HA surface complex, which results in the highest mineralization rate in the period of 150–390 min. Our findings demonstrated that the current system is very promising for complex mixture-containing water purification without additional energy. [ABSTRACT FROM AUTHOR]

[Display omitted] • HA was efficiently mineralized in an Fe0-Fe y C z /Fe x -GZIF-8-rGO aqueous suspension. • The polar alkane-alcohol complex was formed with more single electrons on –OH group. • The polar alkane-alcohol complex enhanced its surface cleavage and •OH formation. • The reaction kinetics depends on the surface complex characteristic. Natural organic matter (NOM) has diverse negative impacts on water purification, however, preventing them occurrence very difficult. Herein, humic acid (10 mg/L), as the main component of NOM, is completely destructed within 120 min in the Fe0-Fe y C z /Fe x -GZIF-8-rGO air-saturated aqueous suspension without additional energy input, while its mineralization is followed by three kinetic constants within 480 min. During the process, HA was first complexed with Fe0-Fe y C z /Fe x -GZIF-8-rGO by π-π interaction and H-bonding interaction and cleaved to aromatic compounds and then to alkanes and alcohols with some small acids before 120 min. The electron paramagnetic resonance (EPR) analysis and density functional theory (DFT) calculations confirmed that a strongly polarized alkane-alcohol complex was formed after 150 min with an electron-rich hydroxyl group area in alcohol and an electron-poor alkane area. Moreover, the more electrons of alkane in the complex are delocalized and trapped by O 2 , with the adsorption of the alkane-alcohol complex on the catalyst surface based on the analyses of both electrochemical impedance spectroscopy (EIS) and chronoamperometry, greatly promoting the surface cleavage and hydrolytic process of alkane in the complex and producing more •OH for pollutant degradation than it does from the HA surface complex, which results in the highest mineralization rate in the period of 150–390 min. Our findings demonstrated that the current system is very promising for complex mixture-containing water purification without additional energy. [ABSTRACT FROM AUTHOR]

[Display omitted] Herein, a novel metal-free catalyst consisting of multiporous oxygen-rich carbon–nitrogen graphene-like nanosheets (O LAA -CN NSs) is first developed through a staged temperature-programmed calcination of l -ascorbic acid (LAA)-modified dicyandiamide precursor. It is found that the oxygen species from l -ascorbic acid (O LAA) are introduced into the graphene-like basic matrix and replace partial N atoms to form the C O C-R structure, leading to the non-uniform distribution of electrons on the catalyst surface, and the formation of electron-rich centers around the C O C microareas according to a series of characterization techniques. As a result, O LAA -CN NSs exhibits excellent performance for refractory pollutant removal in the presence of peroxymonosulfate (PMS) and dissolved oxygen. Some pollutants with complex structures are even completely degraded within only 1 min. The interface reaction mechanism is further revealed that PMS mainly acts as an active inducer to drive the electron donation of pollutants over O LAA -CN NSs. These electrons are finally utilized by dissolved oxygen to generate reactive oxygen species (ROS) through the interface process. This reaction system results in pollutants that can either be cleaved directly by surface oxidation process or degraded by the attack of the generated ROS, such as singlet oxygen (1O 2) and superoxide radicals (O 2 •−), through oxygen activation, which significantly reduces the resource and energy consumption in advanced wastewater treatment by harnessing the energy of pollutants and dissolved oxygen in the water. [ABSTRACT FROM AUTHOR]

A novel Ce-doped manganese oxide octahedral molecular sieve (Ce-OMS-2) was prepared by a reflux method and characterized by field emission scanning electron microscope, high resolution transmission electron microscopy, Fourier-transform infrared spectra, nitrogen adsorption/desorption isotherms, X-ray diffraction and X-ray photoelectron spectroscopy. The Ce(0.48)-OMS-2 with Ce/Mn molar ratio of 0.48 was highly effective and stable for the degradation of ciprofloxacin in water. The characterized results indicated that Ce mainly entered the tunnel structure of OMS-2, significantly increasing the BET surface area from 72 m 2 /g for OMS-2 to 304 m 2 /g for Ce(0.48)-OMS-2. Moreover, the surface oxygen defects and surface labile oxygen significantly increased after the introduction of Ce into OMS-2, being determined by the O1s spectra and O 2 -TPD analysis. The ESR and activity tests under different conditions suggested that the reduced manganese Mn(II) could interact with surface labile oxygen to form O 2 − and Mn(IV), resulting in the high activity of Ce(0.48)-OMS-2 to degrade the piperazine ring and the quinolone moiety of CIP into small molecular products. Simultaneously, the release of Mn(II) was inhibited by the electron transfer process on the micro-interface of Ce(0.48)-OMS-2. [ABSTRACT FROM AUTHOR]

[Display omitted] The heterogeneous Fenton process suffers from low efficiency because of the low electron transfer cycle rate of Fe3+/Fe2+, which often consumes enormous amounts of hydrogen peroxide (H 2 O 2) or other energy. Herein, we report a novel Co-based Fenton-like catalyst (in-situ -Co-g-C 3 N 4) synthesized via the surface complexation method, in which Co species were modified in situ into the framework of the graphitic carbon nitride (g-C 3 N 4) substrate through C–O–Co chemical bonding. The catalyst exhibited higher Fenton-like catalytic activity than pure g-C 3 N 4 in the degradation of various pollutants under neutral conditions, as evidenced by the approximately 150-fold higher Fenton-like reaction rate constant of in-situ -Co-g-C 3 N 4 than that of g-C 3 N 4. Density functional theory (DFT) calculations and a series of experimental and characterization analyses revealed the interfacial reaction mechanism between H 2 O 2 , pollutants and in-situ -Co-g-C 3 N 4. During the Fenton-like reaction, the electron-poor C center on the aromatic ring of g-C 3 N 4 could capture the electrons deprived from pollutants, and subsequently deliver them to around the electron-rich Co center to efficiently reduce H 2 O 2 to hydroxyl radicals (•OH), enabling H 2 O 2 to be used efficiently for the degradation of pollutants. This study provides a strategy for improving Fenton-like degradation efficiency by effectively utilizing the energy of organic pollutants. [ABSTRACT FROM AUTHOR]

Herein, we fabricated CoCu-0.25-O v with ternary Co...O v ...Cu sites through simple co-precipitation to achieve effective co-utilization of organics and dissolved oxygen (DO) as endogenous electron donor-acceptor in Fenton-like system. Around 100% of dimethylamine (DMA) min within 30 is removed. The involved kinetics (0.22 min−1) and oxidant utilization efficiency (22.5%) are higher than controls with binary sites. Multi-scaled characterizations and theoretical calculations reveal that electron-polarized Co...O v ...Cu sites facilitate co-activation of DMA and DO as electron donor-acceptor through increasing d -band center and lowering work function of catalyst. Meanwhile, ternary sites favor 1O 2 and SO 4 •− generation, and shorten the migration distance of active species to pollutant, thus achieving excellent dual performance improvements. Semi-quantitative results of ESR indicate that DO activation and peroxymonosulfate (PMS) oxidation contribute about three-fourths and one-fourth to 1O 2 production, respectively. This contribution provides a new and sustainable strategy for high-efficiency and oxidant-saving removal of refractory pollutants in the environment. [Display omitted] • Co...O v ...Cu sites greatly improve removal performance of DMA and PMS utilization rate. • Ternary sites activate DMA and DO to replace PMS and favor the formation of ROSs. • Increased d -band center and lower work function of catalyst boost the co-activation. • DMA is removal by enhanced multipath (self-oxidation, 1O 2 and SO 4 •− attacks). • O 2 activation and PMS oxidation contribute 3/4 and 1/4 to 1O 2 formation, respectively. [ABSTRACT FROM AUTHOR]

A low-consumption water purification system is firstly constructed based on a new dual-reaction-center (DRC) catalyst molybdenum-doped zinc sulfide (Mo-ZnS, MZS) with a confined nonequilibrium surface. The extremely strong electron trapping ability of the Mo site is realized by the substitution of Mo for ZnS lattice. In this way, the electrons of emerging contaminants (ECs) are efficiently transferred to the nonequilibrium surface through the oriented interface process (Mo-S-Zn bond bridge), and obtained by the natural dissolved oxygen (DO) to generate hydrogen peroxide (H 2 O 2) under trace H 2 O 2 trigger without light and electricity assistant. The highest yield of H 2 O 2 is even up to ∼230 % of the initial value, and the ECs removal can reach 100 % within 60 min, which is far superior to conventional Fenton catalysts. This work realized the efficient utilization of the contaminant electrons through the construction of Mo-S-Zn bond bridge, which greatly reduced the energy consumption of water purification and improved the resourcefulness of ECs. [Display omitted] • DRC catalyst MZS with the confined nonequilibrium surface is first prepared. • MZS shows excellent performance for water purification. • Efficient H 2 O 2 generation is achieved without light and electricity assistant. • The highest H 2 O 2 concentration reaches up to ∼230 % of the initial concentration. • ECs electrons are efficiently utilized in ORR processes and water purification. [ABSTRACT FROM AUTHOR]

• Excellent activity for water purification is realized in cobalt-zinc ferrite/PMS system. • Surface oxygen vacancy induces PMS activation to generate •OH, SO 4 •− and H 2. • An efficient dual-pathway removal of pollutants is first achieved in PMS activation. • Pollutants replace PMS as electron donors for the V O -rich ZnFe 0.8 Co 0.4 O 2.4 system. • A novel solid-liquid interfacial reaction mechanism is proposed in PMS activation. Peroxymonosulfate (PMS) activation in heterogeneous processes for pollutant degradation is a promising water purification technology. However, the existed rate limiting step greatly restrains its performance and increases the consumption of PMS and energy. Herein, we offer a new strategy to solve this problem. In this work, surface oxygen vacancy (V O)-rich ZnFe 0.8 Co 0.4 O 2.4 nanoparticles were prepared and characterized, which exhibited high activity and stability for refractory pollutant degradation with PMS activation. It was found that PMS ([O 3 S O I O II H]−) could be adsorbed and trapped by the surface oxygen vacancies in the form of O I - Vo or O II - Vo during the reaction. Different electron transfer pathways from Vo to different O sites of PMS was realized in the solid-liquid interface based on the generation of OH, SO 4 − or H 2 from PMS reduction. Pollutants were predominantly adsorbed at metal Co sites in which their electrons were captured by metal species and then transferred to the surface oxygen vacancies, achieving efficient recycling of electrons in the aqueous suspensions. This system achieves a dual-pathway degradation of pollutants and electron transfer from pollutants to PMS to produce free radicals and H 2 , essentially changing the traditional concepts of pollutant removal and providing a sustainable strategy for pollutant utilization during water purification. [ABSTRACT FROM AUTHOR]

• Mesoporous reduction state cobalt species-doped silica nanospheres are first prepared. • Excellent activity is realized in mp -RSCo-SiO 2 NSs/H 2 O 2 system. • Efficient dual-pathway degradation of pollutant is achieved in Fenton-like process. • Pollutants replace H 2 O 2 as electron donors for the mp -RSCo-SiO 2 NSs system. • A new interfacial Fenton-like reaction mechanism involving pollutants is proposed. A novel heterogeneous Co-containing Fenton-like catalyst consisting of mesoporous reduction state cobalt (RSCo)-doped silica (SiO 2) nanospheres (mp -RSCo-SiO 2 NSs) was prepared by an enhanced hydrothermal process. The catalyst exhibited very high activity and stability for a series of refractory pollutant degradation in a very wide pH range of 3.1–10.9. The Fenton-like reaction rate constant of this Co-containing catalyst was approximately 290 times higher than that of Co 3 O 4 for pollutant degradation under the neutral and mild conditions. Based on the characterization, the catalyst possessed a porous nanosphere morphology, and the reduction state cobalt species, including nano-zero-valent cobalt (nZVCo) and Co2+, were found to be generated in the SiO 2 framework through forming Co O Si bonds. During the Fenton-like reaction, the electron donation effect of organic pollutants was successfully realized through the interaction of "Pollutants → Co2+/0-SiO 2 ". The obtained electrons from pollutants were transferred to the catalyst surface and captured by H 2 O 2 , resulting in the generation of hydroxyl radicals (OH). Therefore, a dual-pathway degradation of the pollutants was realized: (I) oxidation and degradation as the electron donors for the system and (II) attacking and destruction by OH radicals. This work provided a new perspective on the effective utilization of the electrons of pollutants and the improvement of Fenton reaction efficiency. [ABSTRACT FROM AUTHOR]

• Dual-electric centers catalysts cooperate with microbes to effectively remove CIP. • Delocalized electrons of absorbed CIP captured by microbes at the electron-rich area. • The catalysts synergize extracellular electron transfer for the cleavage of CIP. • The accumulation of antibiotic resistance genes was reduced by the catalysts. Antibiotics and antibiotic resistance genes (ARGs) are still a problem in biological treatment. Herein, we propose a synergetic strategy between microbes and dual-electric centers catalysts (CCN/Cu-Al 2 O 3 /ceramsite) for Ciprofloxacin (CIP)-contained (5 mg/L) water treatment in an up-flow biological filter. CIP was cleaved into small molecules by the catalyst, bringing a 57.6% removal and reducing 10.5% ARG. The characterization results verified that a Cu-π electrostatic force occurs on the catalyst surface, forming electron-rich areas around Cu and electron-poor areas at the carbon-doped g -C 3 N 4 (CCN) aromatic ring. Thus, the electrons of adsorbed CIP were delocalized and then captured by the adsorbed extracellular polymeric substance at the electron-rich areas. Therefore, the synergetic process weakened the stress of CIP on bacteria and reduced ARG accumulation. It also enriched more electro-active bacteria on the surface of CCN/Cu-Al 2 O 3 /ceramsite, promoting the expression of extracellular electron transfer-related genes and reconstructing the energy metabolism mode. This result provides an opportunity for refractory antibiotic treatment in the biological process. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Single-atom Co-N 4 sites were constructed in Co-doped g-C 3 N 4. • The k obs of CBZ degradation reached 0.355 min−1, while PMS decomposition was mild. • 1O 2 and Co(IV) = O both played an important role in the degradation of CBZ. • PMS → OH*→Co(IV) = O → OO*→1O 2 was proposed as the optimal evolution path of PMS. • The release of 1O 2 was the rate-determining step in the path of Co(IV) = O to 1O 2. Tailoring the interfacial reaction pathway and low consumption strategy for the high efficiency Fenton-like processes is environmentally desirable but still challenging. Herein, single Co atom-doped g-C 3 N 4 was prepared for peroxymonosulfate (PMS) activation to reveal the interfacial reaction of high-valent cobalt-oxo species [Co(IV) = O] to singlet oxygen (1O 2) and construct an energy efficient Fenton-like system. Experimental results showed that the system could achieve 99.6% carbamazepine removal with k obs of 0.355 min−1, while the decomposition of PMS was mild (0.0988 and 0.00917 min−1 in 0–2 and 2–30 min, respectively). Mechanistic studies revealed the reaction of Co(IV) = O to 1O 2 , which moderated the reduction of Co sites, thus slowing the decomposition rate of PMS. But the synergistic effect of 1O 2 and Co(IV) = O maintained the high activity of the system. Combined with first-principles calculations, the optimal evolution path of PMS was PMS → OH*→Co(IV) = O → OO*→1O 2 , accompanied by the Co(II)/Co(III)/Co(IV) redox cycle. The work proposed a new interfacial reaction in term of Co(IV) = O triggered 1O 2 generation, resulting in the construction of an energy-efficient Fenton-like system and provided a novel idea for the development of efficient and low consumption water purification technology. [ABSTRACT FROM AUTHOR]

[Display omitted] • Pigeon manure biochar with electron poor/rich regions on the surface. • Biochar (5 g/L) can significantly increase cumulative methane production. • Adding biochar facilitated the enrichment of methanogenic archaea. • Metagenomes reveal synergistic mechanisms between functional microbes. Inefficient electron transfer is a key bottleneck for anaerobic digestion (AD), which often leads to system instability. Here, we propose for the first time a new strategy to solve the problem by adding surface electron-polarized biochar to enhance methanogenesis by providing electrons to methanogens through surface electron-poor/rich regions. Pyrolysis conversion of pigeon manure to conductive materials (CM) containing electron-poor/rich regions is realized. Different levels of CM (2.5, 5 and 7.5 g/L) are used to enhance methane production from pig manure and rice straw co-digestion systems. It is found that the addition of 5 g/L CM results in the highest cumulative CH 4 production (187.4 ± 8.0 mL/g VS substrate), 35.4% higher (P < 0.05) than the control (0 g/L). Methanogenic archaea are enriched. Synergistic metabolic mechanisms between the functional microorganism bin.CM52.160 (cellulose degradation) and bin.CM03.101 (methane production) are revealed by the metagenomic binning strategy. A large number of potentially unculturable electroactive microorganisms have been identified. This work provides important insights into the construction of micro-electric fields on material surfaces and offers a practical approach to improving AD performance. [ABSTRACT FROM AUTHOR]

Abstract Drinking water distribution systems (DWDS) may be a "Trojan Horse" for some waterborne diseases caused by opportunistic pathogens (OPs). In this study, two simulated DWDS inoculated with groundwater were treated with chlorine (Cl 2) and ultraviolet/chlorine (UV/Cl 2) respectively to compare their effects on the OPs distributed in four different phases (bulk water, biofilms, corrosion products, and loose deposits) of DWDS. 16S rRNA genes sequencing and qPCR were used to profile microbial community and quantify target genes of OPs, respectively. Results showed that UV/Cl 2 was more effective than single Cl 2 to control the regrowth of OPs in the water with the same residual chlorine concentration. However, the OPs inhabiting the biofilms, corrosion products, and loose deposits seemed to be tolerant to UV/Cl 2 and Cl 2 , demonstrating that OPs residing in these phases were resistant to the disinfection processes. Some significant microbial correlations between OPs and Acanthamoeba were found by Spearman correlative analysis (p < 0.05), demonstrating that the ecological interactions may exist in the DWDS. 16S rRNA genes sequencing of water samples revealed a significant different microbial community structure between UV/Cl 2 and Cl 2. This study may give some implications for controlling the OPs in the DWDS disinfected with UV/Cl 2. Graphical abstract Image 1 Highlights • Opportunistic pathogens in the water, biofilms, corrosion products, and loose deposits of DWDS were quantified respectively. • UV/free chlorine controlled the opportunistic pathogens in water more efficiently than single chlorine. • Opportunistic pathogens in the biofilms, corrosion products and loose deposits were tolerant to UV/free chlorine. • Potential microbial correlations existed between the target opportunistic pathogens. • Apparent shift of bacterial community was captured in both ARs disinfected with UV/free chlorine and chlorine. [ABSTRACT FROM AUTHOR]

[Display omitted] • Zero-added conversion of chicken manure into water treatment catalyst (RCM) is realized. • Electron-poor/rich microregions are successfully constructed on RCM. • Pollutant degradation processes can be driven by a little bit of peroxymonosulfate. • RCM has excellent performance on actual wastewater treatment. • Water treatment with low consumption is achieved by utilization of pollutants. Fecal pollution in rural areas and water pollution caused by emerging contaminants (ECs) are two international environmental problems. Here, we propose a new strategy to address the two problems simultaneously through the resource utilization and harmless transformation of poultry manure as a kind of water purification catalyst with zero addition. The ordered bonding of intrinsic metal-organic species is realized in the resourcelized procedure by a one-stage calcination-annealing method, which results in the formation of electron-rich/poor microregions. With the triggering of a small amount of peroxymonosulfate (PMS), the energy/electrons of ECs are utilized by the dissolved oxygen in water driven by the electron-rich/poor microregions on the catalyst surface. As a result, the system exhibits excellent performance in removing various ECs. The degradation rate can even be maintained above 94.3 % after 10,000 cycles. This work indicates a sustainable approach to the effective utilization and treatment of rural waste and pollutants. [ABSTRACT FROM AUTHOR]

Cu-doped LaAlO 3 perovskite (LaAl 1−x Cu x O 3 ) was synthesized via a Pechini-type sol–gel process for the oxidative degradation of persistent organic compounds. The characterization results show that Cu was incorporated into the structure of sphere-like LaAlO 3 and formed the bond of La/Al O Cu. LaAl 0.95 Cu 0.05 O 3 performed excellent activity and stability for the degradation and mineralization of various organic pollutants through heterogeneous Fenton-like reactions. In the practical reaction process, at the organic pollutant initial concentration of 25 mg L −1 , 1.0 mol H 2 O 2 produces 1.8 mol HO radicals within 60 min and 1.0 mol H 2 O 2 still produces 1.3 mol HO radicals after reaction time of 240 min. The results of ESR and active species trapping experiments indicated that HO radicals acted the dominant role during the degradation of pollutants in LaAl 0.95 Cu 0.05 O 3 /H 2 O 2 system. Combining with in-situ Raman analysis and the XPS results of LaAl 0.95 Cu 0.05 O 3 before and after reaction, H 2 O 2 was predominantly reduced to HO on the electron-rich Cu center, and H 2 O 2 /H 2 O can be dissociated on oxygen vacancies (OVs) to enhance formation of HO on the surface of LaAl 0.95 Cu 0.05 O 3 , resulting in the high catalytic activity of LaAl 0.95 Cu 0.05 O 3 . This efficient material can potentially be used as a promising catalyst for the efficient degradation of organic pollutants in environmental pollution cleanup. [ABSTRACT FROM AUTHOR]

The catalytic activity of H 2 O 2 dissociation and formation on zinc chalcogenides was determined by the surface micro-engineering construction including surface orientation and heteroatomic doping. [Display omitted] • The activity of ZnX depends on the surface orientation and heteroatoms. • H 2 O 2 can dissociate to form •OH on ZnO(1 1 0), ZnSe(1 0 0), ZnTe(1 1 0) and ZnTe(1 0 0). • ZnO (1 1 0) surface can catalyze water oxidation to form H 2 O 2. • The selectivity of water oxidation to form H 2 O 2 can be enhanced by doping. • A descriptor was derived from the valence electrons and electronegativity. Establishing the structure–activity relationship is very important for the design of new catalysts for advanced oxidation process with low energy consumption and high efficiency. In this work, the atomic mechanism of hydrogen peroxide (H 2 O 2) dissociation and formation on zinc chalcogenides (ZnX, where X denotes O, S, Se, and Te) was investigated. It was found that the catalytic activity of H 2 O 2 dissociation and formation on ZnX was determined by the surface micro-engineering construction including surface orientation and heteroatomic doping. H 2 O 2 can dissociate to easily form hydroxyl radicals on ZnO (1 1 0), ZnSe (1 0 0), ZnTe (1 1 0) and ZnTe (1 0 0) surfaces, while only the ZnO (1 1 0) surface can catalyze water oxidation to form H 2 O 2. Furthermore, the H 2 O 2 selectivity of water oxidation on the ZnO (1 1 0) surface can be enhanced by the doping with silver atoms due to the weak adsorption strength of OH*, while introducing copper atom into the ZnO (1 1 0) surface can promote H 2 O 2 dissociation. These results not only unveil the mechanism of H 2 O 2 dissociation and formation on ZnX, but also can provide helpful guidance for the development of new catalytic oxidation systems. [ABSTRACT FROM AUTHOR]

In common advanced oxidation processes, excess reagents and energy are often added to the reaction system to maintain the continuity of the reaction. These additions result in a large waste of resources and energy, which has become a bottleneck in the development of water treatment technology. In this study, we propose a new strategy to solve this problem based on a novel dual-reaction-center (DRC) Fe-ZnS quantum dots (Fe–ZnS QDs) catalyst that forms a non-equilibrium surface with an electron-polarized distribution. Through experimental and theoretical studies, it was verified that the activation of trace amounts of H 2 O 2 could break the energy barrier for pollutants to transfer electrons. The dissolved oxygen (DO) in the reaction system could be activated by gaining energy on the surface of the Fe–ZnS QDs catalyst, and was converted to 1O 2 to attack organic pollution. In addition, the pollutants themselves supplied electrons to H 2 O 2 through the surface of the Fe–ZnS QDs catalyst to generate more •OH radicals for pollutant degradation, thus providing two fast paths for pollutant degradation. The system could drive the reaction through a trace amount of H 2 O 2 , thereby activating DO to generate 1O 2 while effectively using the energy of pollutants. Therefore, the proposed system offers a new direction for the development of environmentally-friendly catalysts and greatly reduces the consumption of resources and energy. [Display omitted] • Fe–ZnS QDs is successfully developed as a Fenton catalyst for the first time. • The surface of ZnS QDs is regulated by trace Fe to form a non-equilibrium surface with an electron-polarized distribution. • The Fe–ZnS QDs/H 2 O 2 system exhibits excellent activity for pollutants degradation. • Inert oxygen species in reaction system are easily activated to 1O 2 to attack pollutants. [ABSTRACT FROM AUTHOR]

A novel metal-free catalyst consisting of typical flower-like graphitized polyimide (g-PI) is first synthesized via an enhanced hydrothermal polymerization process, and it exhibits excellent performance for pollutant removal through peroxymonosulfate (PMS) activation over a wide pH range (3−11). The catalyst is especially effective for attacking the endocrine disruptor bisphenol A (BPA), which can be completely degraded in a short time. Based on the results of characterization, g-PI is consisted of abundant aromatic frameworks with π conjugates based on C-O-C linkages and N-hybrid rings, which play essential roles in the subsequent degradation of pollutants. In the g-PI/PMS/BPA system, BPA (rich in π bonds) is preferentially adsorbed to the catalyst surface through π-π interactions, accompanied by a decrease in its activation energy to produce surface-adsorbed BPA*. This species can be directly attacked and degraded by PMS without the need for the radical processes, which saves the energy required for the intermediate activation process of PMS. On the other hand, the electrons obtained from pollutants are rapidly transferred to the O center, driving PMS activation to generate free radicals. The synergetic interface process offers excellent potential for practical wastewater purification. [Display omitted] • g-PI is synthesized by graphitization of metal-free polyimide (PI). • g-PI/PMS system shows excellent activity in degrading organic pollutants. • Pollutants are preferentially adsorbed on the surface of g-PI through π-π interactions. • Surface-adsorbed species can be directly oxidized by PMS without the need for radical processes. [ABSTRACT FROM AUTHOR]

d-g-C 3 N 4 -Fe composites was prepared via a self-assembly and calcination process. According to measurements and density functional theory (DFT) computations, the complexation of iron and pyridinic N of g-C 3 N 4 (Fe‒N) occurred with Fe(III)-π interaction, causing more oxygen vacancies (OVs) with more electrons in iron oxides. In the catalyst air-saturated suspension, the adsorbed pollutants complexed surface Fe(III) through their hydroxyl group donated electrons to around OVs, reducing the surface Fe(III) to Fe(II) and were destructed by Fe(III)-π interaction of the complexation. The addition of H 2 O 2 mainly acted as acceptor being reduced •OH at the OV centers, causing higher degradation rate of pollutants due to both •OH and the surface reaction. However, for the adsorbed hydrophobic pollutants onto the sites of peripheral structure in g-C 3 N 4 , H 2 O 2 was mainly decomposed into O 2 by the synergistic effect of iron species and OVs. Therefore, the catalyst exhibited high Fenton-like efficiency for the degradation of hydroxyl-containing pollutants and hydrophobic pollutants mixing with the former. Our results demonstrate that the Fe(III)-π interaction could carry out the oxidation of pollutants on the catalyst surface, decreasing the consumption of H 2 O 2 , and the role of OVs depends on pollutant adsorption patterns. ga1 • Fe‒N complexation formed between g-C 3 N 4 and iron oxide in d-g-C 3 N 4 -Fe. • More oxygen vacancies produced in iron oxide of d-g-C 3 N 4 -Fe. • Degradation of organics was performed from the surface oxidation rather than •OH. • d-g-C 3 N 4 -Fe shows excellent activity for hydroxyl-containing pollutants degradation. • Efficiency of H 2 O 2 depended on the synergistic effect of OVs and pollutant adsorption. [ABSTRACT FROM AUTHOR]

• Heterogeneous Fenton-like reaction was studied using a pilot scale test. • TCM, DCAA and TCAA were the main compositions of DBPs in drinking water. • C1-C5 and F1-F5 of NOM were the main precursors of different DBPs. • This treatment improved removal efficiency of DBPs and NOM without adjusting pH. • This treatment process also controlled the genotoxicity of drinking water. This paper explores the removal of natural organic matter (NOM) and disinfection by-products (DBPs) in drinking water by heterogeneous Fenton-like oxidation and granular activated carbon (GAC) filtration in a pilot scale test without adjusting pH of the water. pH of the used water in this study was from 7.5 to 8.7. Comparing with conventional water treatment processes, heterogeneous Fenton-like reaction and GAC filtration increased the removal rate of dissolved organic carbon (DOC), NOM with different apparent molecular weight (AMW) (F1-F7) and with different compositions (C1-C5) to 75.11%, 88.65% and 58.73%, respectively. Moreover, heterogeneous Fenton-like reaction and GAC filtration increased the removal rate of DBPs to 88.18%. The multivariate statistical analysis indicated that haloacetic acids (HAAs) and haloketones (HKs) mainly came from fulvic-like and humic-like NOM with AMW lower than 1.5 K Da. These substances with AMW between 1.5 K Da and 3.5 K Da were the main precursors of trihalomethanes (THMs). The main precursors of halonitriles (HANs) were soluble microbial byproduct-like (SMP-like), tyrosine-like and tryptophan-like substance with the AMW between 3.5 K Da and 4.5 K Da. Overall, without adjusting pH of water, heterogeneous Fenton-like reaction and GAC filtration improved the removal efficiency of NOM and DBPs, and controlled the genotoxicity of drinking water. [ABSTRACT FROM AUTHOR]

• N-doped porous carbon was prepared via transformation from graphitic carbon nitride. • N-doped porous carbon (NC 1.0) possesses ultrahigh N content up to 33.75 at%. • NC 1.0 exhibits excellent reactivity and stability for peroxymonosulfate activation. • DFT calculations reveal PMS activation involving PMS reduction and oxidation. • Singlet oxygen (1O 2) is the main reactive oxygen species in the NC 1.0 /PMS system. Nitrogen-doped carbon materials are proposed as promising metal-free catalysts for persulfate-mediated catalytic oxidation process, yet the nitrogen content in the final carbon products is typically low. Moreover, controversies remain in the unambiguous identification of active sites in nitrogen-doped carbons for persulfate activation. Here we report the facile synthesis of nitrogen-doped carbon material via one-step pyrolysis of urea and D-mannitol, which simultaneously combine ultrahigh nitrogen content (up to 33.75 at%) with apparent porous structure via transformation from graphitic carbon nitride. With this strategy, the highly nitrogen-doped porous carbon (NC 1.0) exhibits excellent catalytic activity toward peroxymonosulfate (PMS) activation for oxidation of organic pollutants. Both experiments and density functional theory (DFT) calculations, for the first time, revealed that the electron-rich graphitic N and electron-deficient carbon atom adjacent to graphitic N in NC 1.0 served as active sites for PMS reduction and oxidation toward the generation of hydroxyl radical (OH) and singlet oxygen (1O 2), respectively, in which PMS oxidation was the main reaction in the course of PMS activation rendering 1O 2 the dominant reactive oxygen species (ROS) in the NC 1.0 /PMS system. More importantly, NC 1.0 presents robust stability in PMS activation, superior to most reported nitrogen-doped carbon-based catalysts, offering great promise for practical environmental remediation. [ABSTRACT FROM AUTHOR]

• Effect of biofiltration with CAC on DBPs and pathogenic bacteria were investigated. • CAC resulted in higher biological removal of DOC and DBPs precursors. • Less microbial biomass, metabolites and smaller microbial clusters were detected in the effluent of CAC. • The EPS in CAC exhibited superior characteristics on improvement of water quality. • CAC maintained the safety of water quality continually in downstream DWDSs. The change of water quality was investigated in pilot-scale ozone-biological activated carbon (O 3 -BAC) filters using an emerging coconut shell-based granular activated carbon (CAC) or traditional granular activated carbon (GAC), respectively. More dissolved organic carbon (DOC) and disinfection by-products (DBPs) precursors were removed, meanwhile, less microbes, less metabolites and smaller microbial clusters were detected in the effluent of CAC compared with GAC. Sequentially, lower DBPs formation and higher disinfection efficiency were achieved in drinking water distribution systems (DWDSs). Furthermore, it was observed that extracellular electron transfer was enhanced in the attached biofilms of CAC, hence improving the microbial metabolic activity and biological removal of DOC. The results were attributed to the strong interaction of extracellular polymeric substances (EPS) with highly graphitized CAC. In addition, CAC resulted in totally different EPS in attached biofilms with superior characteristics including stronger viscosity, higher flocculating efficiency, mechanical stability and numerous binding sites for bacterial cells. Consequently, a wide range of compact interconnected biofilms formed on the surface of CAC and exhibited certain binding effect for microbial flocs and metabolites. Therefore, CAC resulted in higher microbial metabolic activity and lower release of microbes and metabolites, which was beneficial to maintain water quality safety in downstream DWDSs. [ABSTRACT FROM AUTHOR]

• Nanoscale Fe 2 (MoO 4) 3 is successfully developed as a HPPA catalyst. • Fe 2 (MoO 4) 3 HPPA process can rapidly degrade micropollutants via two pathways. • An interfacial reaction mechanism for inhibiting e−/ h+ recombination is revealed. • Persulfate is responsible for capturing photogenerated electrons to produce SO 4 −. • Pollutants can capture holes and be oxidized through HPPA synergistic process. Photogenerated electron-hole recombination has been a bottleneck problem for photocatalytic reactions for a long time. Herein, we propose an efficient solution strategy through capturing electrons and holes with environmental factors. In this study, nanoscale iron molybdate (Fe 2 (MoO 4) 3) was successfully synthesized, characterized and used in a heterogeneous photo-combined persulfate (PS) activation (HPPA) process for micropollutant removal. The reaction rate in this system was ˜98 and ˜59 times higher for Fenton-like and photocatalytic oxidation alone, respectively, which was attributed to strong synergistic effects of HPPA process. During the HPPA reaction, PS could quickly capture the photogenerated electrons to produce sulfate radicals (SO 4 −), which was further converted to hydroxyl radicals (•OH) in water. Induced by PS, the electron-rich pollutants could actively capture the holes and be oxidized and degraded. This synergistic process not only inhibited the electron-hole recombination but also enabled rapid dual-pathway degradation of pollutants through free radical attack and hole oxidation. [ABSTRACT FROM AUTHOR]