The extensive use and inevitable release of graphene oxide (GO) to the environment have increased the threat of its exposure to living organisms. This study reports the design of Fe-based hydroxides with different interlayers anions, i.e., Cl-, SO42-, CO32-, and NO3- to capture GO from an aqueous medium. Various characterization techniques, including X-ray diffraction (XRD), Fourier transform infrared (FTIR), and scanning electron microscopy (SEM), confirmed the successful synthesis of these different materials. The Fe-hydroxides as Fe-HO/(NO3) with NO3- interlayers anions effectively removed up to 190 mg/g GO and was tolerant to a high concentration of background electrolyte, different anions, and increasing ionic strength. These remarkable features of Fe-HO/(NO3) originated from the weak bonding abilities of interlayers NO3- anions that facilitated simple self exfoliation of hydroxide nanosheets, and thus promoted the electrostatic interactions between the positively charged layers of hydroxides and negatively charged GO particles. The coagulated end product (Fe-HO/(NO3) @GO can be further used in advanced oxidation processes (AOPs) as catalyst or adsorbent for the treatment of different pollutants. We believe that this work not only explains the positive aspect of regulating anions in the hydroxides layers but also provides a direction to develop new materials for environmental remediation.

This study proposed a step-by-step oxidation process based on the in-depth analysis of the catalytic mechanism of peroxymonosulfate (PMS) activated by the common MnO2-based catalyst-manganese octahedral molecular sieve (OMS-2). In the first stage, OMS-2-mediated electron transfer dominated the oxidation process. When PMS was completely consumed, the reaction entered the second stage, at which singlet oxygen (1O2) gradually turned into primary oxidation source. OMS-2-mediated electron transfer was proved based on the results of electrochemical analysis, phosphate substitution experiments, and Raman tests. Meanwhile, the oxidation process of 1O2 was unveiled by radical scavenging tests, electron paramagnetic resonance (EPR), and solvent-exchange experiment (from H2O to D2O). Moreover, superoxide radical (O2 center dot- ) generated from the reaction between PMS and metastable manganese intermediate was identified as the precursor of 1O2. O2 center dot- generated in the first stage could significantly extend its half-life by adsorbing on the (211) plane of OMS-2, and then desorbed in the second stage and contributed to the formation of 1O2. More importantly, through the transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and DFT calculations, the essence of step-by-step oxidation driven by O2 center dot- adsorption-desorption process was uncovered.

原位好氧稳定化技术是老填埋场生态修复和二次污染控制的主流技术.目前对于该技术的计算与设计主要依赖于项目经验.对老填埋场原位好氧稳定化技术中气体循环系统的工艺设计与计算进行了研究和总结.对于注气系统中的理论需氧量、抽/注气管道和风机选型、稳定化周期的计算和相关单体的设计提出了计算方法和设计参考.研究成果将为原位好氧稳定化项目的计算与设计提供理论依据与参考.

The introduction of non-metal heteroatoms is an effective way to improve the catalytic properties of heterogeneous catalysts to peroxymonosulfate. Unfortunately, the influence of foreign elements on the catalytic process has not been deeply revealed. Herein, we reported a series of Co9S8 nanorods catalysts from Co3O4 precursor with different S doping ratios. S doping effectively enhanced the catalytic properties, and the catalytic process gradually switched from non-radical (O-1(2)) into radical (SO4 center dot-) with the increase of S doping ratio. Moreover, quenching experiments, EPR, XPS, and radicals quantification indicated that the concentration of O-1(2) exhibited a linear relationship with Delta OL. Indicating that O-1(2) was derived from the reaction between PMS and OL. S doping also altered the valency of cobalt. In Co3O4/PMS, ROS was generated through Co3+/Co2+ catalytic circle. However, in Co9S8/PMS, Co3+/Co2+/Co-0 were all involved and accounted for the generation of ROS due to the low redox potential of S2-. Our work may provide some new clues and strategies for studying the influence of foreign elements on the catalytic process in PMS-based heterogeneous catalytic system.

Wide-ranging researches have been executed to treat groundwater from different mining areas, although complex behaviors of diverse metal ion species in the groundwater have not been illustrated clearly. This research study explored the mechanisms through which Pb(II) and V(V) are eliminated in single and binary-metal removal processes by oxygen, nitrogen, and sulfur-doped biochars also considering the kinetic and characterization techniques. The adsorption efficiency of V (V) was enhanced by oxygen-doped biochar at pH 4 with an adsorption capacity of ~70 mg/g. However, Pb (II) was rapidly removed at pH 6 with a higher adsorption capacity of ~180 mg/g by the nitrogen and sulfur-doped biochar forming PbCO3 and V(CO)6 crystals along the single-metal removal process. These results could be explained by the Hard Soft Acid Base theory. The hard Lewis acid vanadium was attracted by the hard Lewis base oxygen, and the intermediate Lewis acid lead was attracted by the intermediate and soft Lewis base nitrogen and sulfur. Besides, the removal ability of Pb(II) and V(V) in the binary-metal removal process showed a similar phenomenon for all types of biochars at pH 4 with the adsorption capacity of ~400 mg/g for Pb(II) and 175 mg/g for V(V), but the composition of vanadium species remains unclear on the surface of the biochars. Initially, H3V2O7−, H2VO4−, and HVO42− species were electrostatically attracted by the oxygen-based functionalities, then V(V) species was partially reduced to VO2+ by the oxygen, nitrogen, and sulfur functionalities in different ratios. Finally, H3V2O7−, H2VO4−, and HVO42− species produced Pb5(VO4)3Cl and Pb2V2O7 which co-precipitate with Pb(II), but VO2+ does not generate any form of precipitates. The above-explained technique supports the treatment of vanadium mining groundwater with valuable vanadinite (Pb5(VO4)3Cl) mineral.

In this paper, we surprisingly found that the incorporation of unreducible metal oxides MxOy (M = Mg, Zn, Ca, Ba, Al) onto CuO hybrid magnetic nano ferric oxide (Cu@Fe3O4) may alter the reaction pathway in persulfate activation, and increase the reaction rate constant. The activation of peroxymonosulfate (PMS) by Cu@Fe3O4 led to a classic sulfate radical based oxidation process (SR-AOP) with an acetaminophen (ACE) degradation rate constant of 0.004 min(-1), while O-1(2)-dominated nonradical oxidation process was disclosed in CuM@Fe3O4 with wildly fluctuated reaction rate constants from 0.003 to 0.242 min(-1). Mechanism studies indicated that singlet oxygen (O-1(2)) derived from the direct oxidation of superoxide anions radicals (O-2(center dot-)) or the recombination of O-2(center dot-) was the main reactive oxygen species (ROS) in CuM@Fe3O4/PMS system. A series of characterization experiments (pH(pzc) tests, XPS, H-2-TPR, et al.) and DFT calculation disclosed that the addition of an unreducible metal M yielded many positive effects: (1) the formation of surface oxygen vacancies (O-V) raised the zero point charge (pH(pzc)) of CuM@Fe3O4, thus enhanced the adsorption and activation of PMS; (2) promoting the generation of a new Cu species (Cu3+) on the surface of CuM@Fe3O4, which then participated in the generation of O-1(2). The different reducibility of Cu3+ led to differences in the catalytic properties of CuM@Fe3O4. In addition, the effects of various water matrix species and the results of reusability experiment, mineralization experiment, and ecotoxicity test exhibited that CuM@Fe3O4/PMS system possessed excellent practical application value.

Electrolytic manganese anode slag (EMAS) is the waste residue produced by electrolytic manganese metal industry. At present, no mature recycling system has been established, which causes a waste of resources and threatens the environment. Therefore, the resource utilization of EMAS has attracted increased attention. In this paper, the in-situ resource utilization of EMAS can be realized by pickling treatment was reported. Specifically, EMAS after pickling treatment (PEMAS) was first used as catalyst to activate PMS to degrade tetrachlorophenol (4-CP). Pickling could remove the inert inorganic components on EMAS and increase the specific surface area, pore volume and Mn distribution of the catalyst, thus improving the catalytic performance of the catalyst. Under the conditions of 4-CP of 40 ppm, PMS of 1 mM and PEMAS of 0.3 g L-1, 85% of 4-CP could be degraded within 50 min. Mechanism studies proved that the main active species were O-2 center dot(-) and O-1(2). Some O-2 center dot(-) contributed to the generation of O-1(2) and some O-2 center dot(-) directly contributed to the degradation of 4-CP. During the reaction, the valence state of Mn transformed between Mn(III)/Mn(IV) and Mn(II)/Mn(III) and kept the cycle. Moreover, PEMAS/PMS system exhibited excellent independence of the solution pH, resistance to the versatile inorganic ions and background organic matters, and stability of recycling. In a word, this study has achieved the resource utilization of EMAS and the goal of treating waste with waste, which is a win-win strategy of economic and environmental benefits. (C) 2020 Published by Elsevier B.V.

原位好氧稳定化技术是稳定化程度低的老填埋场生态修复和二次污染控制的主流技术.目前对于该技术的计算与设计主要依赖于项目经验.对老填埋场原位好氧稳定化技术中液体循环系统的工艺设计与计算进行了研究和总结.对于液体系统中的渗滤液导排、抽提与回灌系统提出了计算方法和设计参考.

Highly efficient elimination of anionic chromate remains a critical task from the biological and ecological perspective owing to their carcinogenic effects on the biosphere and ecosphere. In literature, varieties of functional materials have been applied to remove Cr(VI) from the environmental sources. In which the chemical reduction of Cr(VI) to Cr(III) by a reductant and simultaneous adsorption of Cr species is an effective technique for the removal of Cr(VI). Many effective reductants were applied in the past years, which could be categorized according to their active functional atom/group. Although very few studies illustrated the complete coordination mechanisms between Cr ions and functional groups during the reduction coupled adsorption. This review focuses on recently investigated Cr(VI) reduction coupled adsorption systems based on the electron donor (reductant) functionalities with the interactions of Cr2O72 , CrO42 and Cr3+ ions by the metal and nonmetal functional groups. Also, the removal capacity and equilibrium time were analyzed based on the findings from isotherm and kinetic studies. To conclude, we offered our insights based on the coordination of chromium species with various functionalities into future research prospects and issues in the hope of motivating more researchers to involve in this new area of functional materials for environmental pollution control. (C) 2021 Elsevier B.V. All rights reserved.

The fight against coronavirus disease 2019 (COVID-19) is still running its courses. Proper management and disposal of health care wastes (HCWs) are critical to win the fight. To achieve aforementioned tasks, prediction of their production is highly desired. In this study, primary data of production of three kinds of HCWs collected from Wuhan, the first epidemic epicenter worldwide and a mega city with more than 10 million population who has went through a lockdown period of 78 days, were reported for their first time. HCWs were classified into routine HCWs, infectious HCWs (IHCWs) and infectious municipal solid wastes. Among them, infectious HCWs from designated hospitals for COVID-19 were recognized as the most dangerous one. A multiple linear regression (MLR) model was built to predict the production of IHCWs with high significance. Numbers of patients were demonstrated high correlations with the production of IHCWs in an order of confirmed patients > out-patients > suspected patients. By the MLR model, production rates of IHCWs by confirmed, suspected and out patients were determined as 3.2, 1.8 and 0.1 kg/patient, respectively. In addition, constant production of IHCWs during the pandemic period was determined as 13 tons/d. This is the first study on quantitative evaluation of infectious HCWs during COVID-19 pandemic. The achievements in this study have potentials to shed light on global efforts to the prediction, management and disposal of vast HCWs generated in the war against COVID-19. (c) 2021 Elsevier Ltd. All rights reserved.

1研究亮点 * COVID-19暴发期间武汉市将医疗废物分为3类进行管理; *首次报道了武汉市封城期间涉疫医疗废物的第一手数据; *涉疫医疗废物产生量与医疗资源的消耗量呈现明显正相关关系; *建立了 COVID-19暴发期间武汉市涉疫医疗废物预测的多元线性回归模型. 2背景 COVID-19疫情暴发期间,武汉市投入了大量医疗资源用于疫情防控,随之带来大幅增长的涉疫医疗废物.全国范围内医疗废物产生量从2020年1月20日的4 902.8 t/d增长至2020年3月21日的6 606.8 t/d,武汉市的医疗废物产生量更是从疫情暴发前的40～50t/d增长至2020年3月1日的247 t/d.爆炸性增加的产生量对武汉市的涉疫医疗废物收运管理和终端处理带来了极大的挑战.因此,本研究对武汉封城期间3类医疗废物的产生量变化趋势及其与相关病患数量、医疗资源消耗情况的相关性进行了分析,并构建了多元线性回归模型,准确地拟合了涉疫医疗废物的实际产生量.

Recently, various nonradical oxidation mechanisms different from traditional free radicals have been discovered in peroxymonosulfate (PMS)-based heterogeneous catalytic system. These nonradical oxidation mechanisms have given rise to much controversy in many aspects due to their variety and complex evolutionary pathways. In this paper, we systematically summarized and compared these nonradical oxidation mechanisms. Mainly including the evolutionary pathways, identification methods (qualitative and quantitative), and oxidation characteristics. Moreover, the challenges and strategies for the further development of these oxidation mechanisms, as well as the research and application prospects are proposed. Our work can deepen systematic understanding of the nonradical oxidation mechanism among relevant researchers, and provides some enlightenment for using nonradical oxidation mechanism to deal with the environmental crisis.

Recently, extensive researches implemented to decontaminate hexavalent chromium from industrial effluents. Even though, these processes were not comprehensively addressed in various environmental conditions. This paper investigated the reduction plus adsorption mechanism of [Cr2O7](2-) by thiol-based composite in wide range pHs. In this system, firstly the reduction of [Cr2O7](2-) to Cr3+ occurred and Cr species adsorbed by -SH, -NH2, -OH functional groups in different degrees. The pH 2.0 medium underwent partial reduction of [Cr2O7](2-) to Cr3+, besides three-quarter of [Cr2O7](2-) were reduced to Cr3+ and also Cr species adsorbed onto the composite in pH 3.0 medium. The extremely fast reduction occurred within 5 min, which helped the application in the fixed-bed column while diminished the column's residual time. Interestingly, mild acidic pHs have prompted the composite to a well-expanded structure, which further controlled the hydraulic resistance and column blockage. Inspiringly, the [Cr2O7](2-)- composite system can be treated 13 L of 19.87 mg L-1 [Cr2O7](2-) to the Environmental Protection Agency's (EPA) discharge limit by 2.27 g of composite in pH 3.0 with 383 mL of an eluent. As per the Bohart-Adams model, a liter of a fixed-bed column may effectively capture around 60 g of Cr from industrial effluent in pH 2.0 - 3.0. This collective system is an efficient catalytic cycle technique to treat oxyanions from wastewater where replacing toxic oxidants with environmentally friendly catalytic wastewater treatment processes.

In advance oxidation processes (AOPs), modulating the activation mechanism from free radical to the non-radical pathway is the most attractive strategy for the treatment of recalcitrant pollutants. Herein, we achieved this goal after modifying the spinel CuFe2O4 catalyst by introducing non-redox metals (M = Mg, Ca, Ba, and Zn) as CuMFe2O4. The modified catalysts were evaluated for the removal of acetaminophen (ACE) using the persulfate (PS) activated system. The results revealed that the non-redox metals not only enhanced the catalytic activity of CuFe2O4 in the order of Mg > Zn > Ca > Ba but also switched the original radical pathway of CuFe2O4/PS system to the non-radical one (i.e., direct electron transfer path) of CuMgFe2O4/PS system. The critical role of non-redox metals to modulate the reaction mechanism was studied in detail using the extensive radical scavengers, EPR analysis, target pollutants selectivity, electrochemical studies, decomposition of oxidants, and identification of degradation products. Additionally, various experiments and characterizations, including XRD, EPR, H-2-TPR, XPS, and FTIR, showed that the changes in the activation mechanism and catalytic activity (6-8 folds higher in the case of CuMgFe2O4) were related to the generation of a large amount of surface-bound isolated Cu2+ ions and abundant surface hydroxyl groups. The non-radical pathway of the CuMgFe2O4/PS system showed less susceptibility to the changing solution pH, excessive amount of humic acid (HA) or anions, and complete recyclability, and thus demonstrating good practical utility for wastewater. This study provides deep insight into the intrinsic role of non-redox metals to modulate both the activation mechanism and catalytic properties of the catalyst and to design new catalysts for the persulfate-based advance oxidation process.

The slow transformation of Fe3+ back to Fe2+ restrict the practical application of Fe-based catalytic treatment of organic pollutants. Herein, we report a new findings of MgAl-MoS4 to accelerate the redox cycle of Fe3+/Fe2+ in Fe3+/PMS system. Based on the degradation of 4-chlorophenol (4-CP) profile, the rate constant of Fe3+/MgAlMoS4/PMS system was 40 to 42 folds higher than MgAl-CO3/PMS, MgAl-MoS4/PMS and Fe3+/PMS respectively. Moreover, Fe3+/MgAl-MoS4/PMS system was superior both in the degradation efficiency of pollutants as well as in the stoichiometric efficiency of oxidants from the recently reported Fe3+/WS2/PMS, Fe3+/MoS2/PMS or other well-known nano-catalysts systems. This co-catalytic effect of MgAl-MoS4 on the studied redox metals falls in the order of Fe3+ > V5+ > Cu2+ > Mn2+similar to Ag+. Furthermore, the Fe3+/PMS/MgAl-MoS4 system shows smooth degradation over a wide pH (3.0-7.0) and complete stabilities in the recycled studies. Additionally, the presence of excessive amounts of inorganic anions or organic matters also did not influence the degradation profile. In mechanism studies, both the unsaturated S2- and Mo4+ of MgAl-MoS4 were disclosed to fuel electron continuously during the reduction of Fe3+ ions, and thus accelerate the rate limiting step (Fe3+/Fe2+). Additionally, the layered structure, memory effect and suitable surface charge of LDH material also concentrates the reactants molecules and hence, the boosted effect of MgAl-MoS4 was associated with the better adsorption of Fe3+ ions, the faster PMS decomposition, and the acceleration of Fe3+/Fe2+ redox cycle. This work indicates a breakthrough in the field of classical homogenous Fe/PMS system, offers the very first report on the role of Mo6+ and S2- to modulate the redox behaviour of homogenous Fe ions in persulfate based advanced oxidation processes.

Persulfate Fe-based catalytic oxidation is considered as one of the most attractive strategy for the growing concerns of water pollution. However, the undesirable FeIII/FeII redox cycle restrict them from attending the sustainable activity during practical applications. This study was intended to develop a new strategy to regulate the redox cycles of FeIII/FeII by introducing the second redox center of MoS42− in the interlayers of Fe-based layered double hydroxide (FeMgAl–MoS4 LDH). Based on the first-order kinetic model, the fabricated FeMgAl–MoS4 catalyst was 10–100 fold more reactive than the bench marked peroxymonosulfate (PMS) activators including FeMgAl LDHs and other widely reported nano-catalysts such as Co3O4, Fe3O4, α-MnO2, CuO–Fe3O4 and Fe3O4. The enhanced catalytic activity of FeMgAl–MoS4 LDH was related to the continuous regeneration of active sites (FeII/MoIV), excellent PMS utilization efficiency and generation of abundant free radicals. Moreover, the FeMgAl–MoS4/PMS system shows an effective pH range from 3.0 to 7.0 and the degradation kinetics of parahydroxy benzoic acid (PHB) were not effected in the presence of huge amount of background electrolytes and natural organic matters. Based on the in-situ electron paramagnetic resonance spectroscopy (EPR), chemical scavengers, XPS analysis and gas chromatography couple with mass spectrometer (GC-MS), a degradation pathway based on dominant free radicals (•SO4− and •OH), passing through the redox cycles of FeIII/FeII and MoVI/MoIV was proposed for PMS activation. We believe that this strategy of regulating the redox center through MoS42− not only provides a base to prepare new materials with stable catalytic activity but also broaden the scope of Fe-based material for real application of contaminated water.

Over the past, extensive works executed to treat anionic and cationic heavy metal ions from wastewater. Although very few adsorbents were developed to adsorb anionic and cationic heavy metal ions from the same system. In this study, we explored the pH tunable complete reduction plus adsorption mechanism of Pb2+ and Cr2O72- by dithiocarbamate-based composite. The pH study recommended that; adsorption of Pb2+ occurred at pH 5.5, besides Cr2O72- reduction coupled adsorption executed at pH 3. Furthermore, quick adsorption occurred within 60 min with adsorption capacities of 228.69 and 219.75 mg g(-1) for Pb2+ and Cr2O72-, respectively. Adsorption isotherm well described by the Redlich-Peterson model, also adsorption processes were fitted by pseudo-second-order kinetics model. Interestingly, characteristic techniques, a physical monolayer model and thermodynamic models were applied to the experimental results to further understand the adsorption mechanisms. The results indicated that the physical model with two types of interaction energies was more appropriate to interpret the adsorption mechanism. Based on the physical model, three thermodynamic functions were calculated and interpreted to attribute new macroscopic interpretations at the molecular level of the adsorption systems. Inspiringly, the metal-composite system highly effective for 5 regeneration cycles and fixed bed column could decontaminate 17.2 L similar to 10 mg L-1 Pb2+ and 7.3 L similar to 10 mg L-1 Cr2O72- to the EPA's wastewater discharge limit by 5 g of CSC@SDBC with the yielding of 400 and 346 mL of eluent, respectively. Theoretically, a liter of CSC@SDBC column may efficiently adsorb 145,646 mg of Pb2+ and 57,518 mg of Cr2O72- from industrial effluent, these were calculated from the Bohart-Adams model. These collective batch and fixed-bed systems were cost-effective and environmentally tolerable techniques to remove anionic and ca-tionic heavy metal ions from industrial wastewater.

Black liquor (BL) is an agro-industrial residue with high number of lignocellulosic components which could be recognized as a biomass feedstock. In this work, BL coupled with red mud (RM), were applied to prepare cost-effective zero-valent iron (ZVI) embedded in biochar. The oligomers in BL acted as reductants for RM to generate ZVI, while the organic components could be converted into biochar during pyrolysis. The RM/BL demonstrated excellent performance in the removal of Cr(VI) (349.5 mg/g), as the mechanisms were reduction and adsorption. The fixed-bed column study was conducted and 1.7 L simulated wastewater could be treated by 1.0 g RM/BL. After reaction, 95.5% +/- 0.8% and 82.5% +/- 3.2% Cr-loaded adsorbents could be recovered by an external magnet for batch and fixed-bed experiments, respectively. All these results shed light on valorizing these two widespread agro-industrial byproducts, and bridged the knowledge gap between magnetic bio-adsorbent preparation and its industrial practicality on wastewater purification.

Nonradical-based advanced oxidation processes for pollutant removal have attracted much attention due to their inherent advantages. Herein we report that magnesium oxides (MgO) in CuOMgO/Fe3O4 not only enhanced the catalytic properties but also switched the free radical peroxymonosulfate (PMS)-activated process into the 1O2 based nonradical process. CuOMgO/Fe3O4 catalyst exhibited consistent performance in a wide pH range from 5.0 to 10.0, and the degradation kinetics were not inhibited by the common free radical scavengers, anions, or natural organic matter. Quantitative structure-activity relationships (QSARs) revealed the relationship between the degradation rate constant of 14 substituted phenols and their conventional descriptor variables (i.e., Hammett constants σ, σ-, σ+), half-wave oxidation potential (E1/2), and pKa values. QSARs together with the kinetic isotopic effect (KIE) recognized the electron transfer as the dominant oxidation process. Characterizations and DFT calculation indicated that the incorporated MgO alters the copper sites to highly oxidized metal centers, offering a more suitable platform for PMS to generate metastable copper intermediates. These highly oxidized metals centers of copper played the key role in producing O2•- after accepting an electron from another PMS molecule, and finally 1O2 as sole reactive species was generated from the direct oxidation of O2•- through thermodynamically feasible reactions.

A new strategy was applied by periodic stacking of active sites of Cu and reduced graphene oxide (rGO) in the form of Cu-rGO LDH nanohybrid material. The experimental results revealed that newly prepared Cu-rGO LDH nanohybrid material was extremely reactive in PMS activation as evident from the degradation rate of 0.115 min(-1), much higher than Mn-rGO LDH (0.071 min(-1)), Zn-rGO LDH (0.023 min(-1)) or other benchmarked material used during the degradation of bisphenol A (BPA). This excellent activity of Cu-rGO LDH nanohybrid was attributed to the better PMS utilization efficiency as compared to the other catalysts. Additionally, the characterization techniques disclosed that the layer by layer arrangement of active sites in the Cu-rGO LDH catalyst promotes interfacial electron mobility owing to the synergistic association between Cu in LDH and interlayered rGO. Based on the in-situ electron paramagnetic resonance spectroscopy (EPR) and chemical scavengers, singlet oxygen (O-1(2)) was unveiled as dominant reactive species for pollutant removal, resulting from the recombination of superoxides (O-center dot(2)-) or reduction of active Cu centers. We believe that this novel Cu-rGO LDH/ PMS system will open up a new avenue to design efficient metal-carbon nanohybrid catalysts for the degradation of emerging aquatic pollutants in a real application.