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To overcome the defects of easy phase transformation of ferrihydrite and easy aggregation of siliceous ferrihydrite (SiFh) nanoparticles, a novel silicious ferrihydrite−coated halloysite nanorods (SiFh@HNT 40) was prepared by hybridizing halloysite clay nanotubes (HNTs) with ferrihydrite. The SiFh@HNT 40 formed a well-developped mesoporous structure, and exhibited desirable surface properties, as well as excellent Cd(II) adsorption performance over a wide pH range. [Display omitted] The application of amorphous ferrihydrite (Fh) for Cd(II) removal is restricted by its unstable and easily transformable nature. Although doping with silicates stabilized ferrihydrite, its product siliceous ferrihydrite (SiFh) again suffered from the disadvantage of spontaneous agglomeration. Herein, ferrihydrite was hybridized with halloysite nanotubes (HNTs) to prepare a novel siliceous ferrihydrite − coated halloysite nanorods (SiFh@HNTs) in alkaline medium, to break through the current barriers. The characterization results showed that SiFh@HNTs could simultaneously overcome the defects of easy phase transformation of ferrihydrite and easy aggregation of SiFh nanoparticles (NPs). Meanwhile, the optimal SiFh@HNT 40 with halloysite content of 40 % formed a well-developed mesoporous structure and exhibited the desired surface properties: a high specific surface area of 303.4 m2/g, an isoelectric point as low as pH iep = 4.5, and rich functional Fe − OH groups. The formation mechanism of such excellent sturcture–properties of SiFh@HNT 40 were mainly attributed to two factors: the generation of smaller (∼5 nm) SiFh NPs induced by the integration of halloysite-derived SiO 4 4- into ferrihydrite, and the dispersion of SiFh NPs on clay nanotubes. Furthermore, the adsorption capacity of SiFh@HNT 40 for Cd(II) was up to 137.8 mg/g at 30 °C and pH 6, which was much higher than that of aggregated ferrihydrite (11.2 mg/g), halloysite (18.8 mg/g) and goethite (49.4 mg/g). The adsorption thermodynamics study revealed the adsorption of Cd(II) on SiFh@HNT 40 was clearly chemisorption with a (ΔH ads) q of 43.3 kJ/mol. Characterization results of XPS and FTIR confirmed that the rich Fe − OH groups on SiFh@HNT 40 was the main adsorption sites, and Cd(II) was specifically adsorbed by inner-sphere surface complexation. In addition, SiFh@HNT 40 had application potential in the mixed-metal wastewaters treatment. Cyclic regeneration experiments showed that SiFh@HNT 40 had good regeneration performance and could be reused many times. [ABSTRACT FROM AUTHOR]

In this study, we prepared FeMg-LDH loaded with bentonite (FeMg-LDH@bentonite) based on a facile co-precipitating approach in situ for removing heavy metals from water. It provides a new strategy for high efficiency green remediation of heavy metal contaminants. [Display omitted] In this study, FeMg-LDH loaded with bentonite (FeMg-LDH@bentonite) was prepared using the facile co-precipitating method in situ to remove heavy metals from water and then characterized using XRD, SEM, TEM, FTIR, BET, TGA, and XPS. Pb (II) and Cd (II) were selected as the representative heavy metals to evaluate the adsorption capability of the FeMg-LDH@bentonite. The batch adsorption method was adopted to test the effects of the contact time, pH, initial concentration, different cations, and temperatures. The kinetic study indicated that the adsorption of heavy metals onto FeMg-LDH@bentonite was well fitted by the pseudo-second-order method. Isotherms were effectively simulated based on the Langmuir model. The maximal adsorption capability of Cd (II) and Pb (II) can reach 510.2 mg/g and 1397.62 mg/g, exceeding those of conventional adsorbents. The adsorption mechanisms of FeMg-LDH@bentonite demonstrating that there may exist surface complexation, ion exchange, and chemical deposition between FeMg-LDH@bentonite and heavy metals. Moreover, FeMg-LDH@bentonite was found to have a promising application for practically treating wastewater with heavy metals and can be used for various environmental water pollution treatments. The material may be used for heavy metal contaminated soil in the future. [ABSTRACT FROM AUTHOR]

• We reconstructed a complex wetland with nature-based solutions. • This eco-economic system was driven by renewable emergy flows and high exergy. • The mulberry-related industry provided good economic benefits. • The stable equilibria of the eco-economic coupling mode represented a state of synergistic symbiosis. Nature-based solutions (NBS) are effective approaches for solving ecological and economic problems related to wetland reconstruction, while emergy and exergy are well suited for evaluating reconstructed eco-economic systems. In this paper, we executed a wetland reconstruction project involving a mulberry-fir woodland and dike-pond complex (MFWDPC) with NBS in the water-level fluctuation zone of the Three Gorges Reservoir (TGR), China. We evaluated the coupling mode of this eco-economic system by using emergy and exergy theories. After wetland reconstruction, the emergy density that entered the MFWDPC was 1.48E + 18 sej yr−1 hm−2, in which the naturally renewable flow accounted for 96.31 % of the emergy inflows, and the emergy sustainability index (ESI) for the eco-economic system was 708.88. The exergy and specific exergy were 2.41E + 14 j yr−1 and 2.08E + 08 j yr−1 kg−1, respectively, and the emergy/exergy ratio was 1.55E + 03 for the MFWDPC. In addition, mulberry trees with strong flooding tolerance provided good economic benefits due to the use of these plants in reconstructed eco-economic systems. Our study of NBS for wetland reconstruction helps in understanding the synergistic symbiosis between ecosystems and economic systems, thereby promoting the reconstruction of degraded wetlands in China and other regions. [ABSTRACT FROM AUTHOR]

Nanostructured covalent organic frameworks (COFs) have attracted great attentions over the past few decades due to their unique physical and chemical properties. Crystallization is sought in many application fields since it allows enhancing or even promoting properties of catalysis, energy storage and photoelectric properties. However, the crystallization process of nanostructured COFs remains to be challenging. Synthetic approaches to establish nucleation and elongation growth of COFs for controlling crystallization have drawn substantial amount of attentions. Nanostructured COFs have exhibited significant advantages when applied in (electro)photocatalysis and energy storage devices as well. In this review, recent progress in precisely design strategy of fabricating various nanostructured COFs and their applications as (electro)photocatalyzer and energy storage devices are summarized. After a brief introduction of the design principles, composition and interior architecture, the morphology of nanostructured COFs including porous and mesoporous stacked-layer structure, nanosheet structure, nanorod structure, ordered stripe arrays and various nanocomposites are thoroughly described. Reactions dedicated to crystallization process for two-dimensional (2D) COFs are discussed further. Then, the applications of nanostructured COFs as (electro)photocatalysis and energy storage devices are demonstrated. Finally, the potential advantages and challenges for the synthetic technology of nanostructured COFs materials are particularly discussed. Personal insights into the challenges and opportunities on pursuing topologies as hollow structures, dense spheres, yolk–shell structures were raised to broaden the applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • Species richness hotspots were identified by multi-species distribution modeling. • The magnitude and direction of future biodiversity hotspots changes were discussed. • The MaxEnt and InVEST models were complementary in biodiversity conservation. • Suggestions for biodiversity conservation were proposed based on gap analysis. Mainstreaming biodiversity into protection planning and management is of great significance for biodiversity conservation and sustainable development. Species potential distribution modeling is an effective way for species diversity evaluation and biodiversity hotspots identification, which are crucial for biodiversity conservation. Taking the Central Urban Area of Chongqing Municipality as the study area, the main objectives of this study were to identify the potentially suitable habitats, species richness and biodiversity of key protected species in current and future, determine the relative contribution of environmental factors and assess the conservation effectiveness of protected areas (PAs) based on MaxEnt model and gap analysis. The results showed that the current potentially suitable habitats of total key protected species were mainly located in "two rivers and four mountains", with a total area of 1610.55 km2, of which forestland accounted for 59.78 %. Species suitable habitats demonstrated clear topographic heterogeneity, and the distribution index decreased at first and then increased with increasing terrain niche index (TNI). Meanwhile, it was observed that key protected plants and birds shared similar suitable habitats in mountainous areas, with an overlapping area of 753.53 km2, and the high species richness covered 182.83 km2. In 2050, the future biodiversity hotspots would remain stable and increase steadily. In terms of the direction of centroid shift, the biodiversity hotspots would migrate to low latitude, low altitude and southeast by 8.34 km. The jackknife tests indicated that the potential distribution of key protected species was mainly determined by land use, mean diurnal range and TNI. Additionally, the problems of high protection gaps and low protection effectiveness coexisted in the existing PAs, with the overlapping area of the comprehensive biodiversity hotspots and the existing PAs was only 446.96 km2. Finally, suggestions for natural PAs system optimization and ecological protection were proposed. This study provides scientific supports for biodiversity conservation and efficient management. [ABSTRACT FROM AUTHOR]

This paper is a preliminary attempt to quantify the impact of coal mining subsidence on surface ecology. The Yanzhou coalfield of Shandong Province has a long history of longwall coal extraction and the resulting subsidence depressions has created new wetlands. To assess the ecosystem processes of these new wetlands, we determined their eco-exergy based on a structural dynamic method. We used Stella, a software that facilitates construction of structurally dynamic models, including the nutrient cycle, hydrological processes, and large aquatic plant factors. Following calibration and validation, the model was applied to two scenarios to show different trends. The ratio of zooplankton biomass to phytoplankton biomass, transparency in Secchi depth, eco-exergy, and structural eco-exergy were selected as indicators. Understanding eco-exergy can help protect an area's ecological balance and achieve a sustainable use of water and soil resources. [ABSTRACT FROM AUTHOR]

Assisted wet deposition methods to localize the active phase metal on the carrier surface and prevent atomic aggregation during conventional heat treatment are strongly preferred. Herein, single-atom cobalt catalysts (SA-Co-PCN) with different metal-central content were target-prepared using a combination of impregnation and secondary annealing on polymerized carbon nitride (PCN) through reticular confinement. Fitting the coordination configuration of the Co-N pathway within the first coordination shell according to quantitative EXAFS indicated that the ligancy of Co-N was 4. The removal efficiency of representative micropollutants in the SA-Co-PCN/PMS system achieved 100% within 15 min. The outstanding degradation properties of micropollutants were ascribed to the SA-Co-PCN boosts PMS to a 1O 2 -dominated system. Moreover, the effects of substituents on the degradation behavior and ecotoxicology of sulfonamides (SAs) in PMS-activated systems were investigated in depth. The combination of DFT theoretical calculations and LC-MS further confirmed that the similar electron-rich sites on the SAs molecules allowed for commonality in the degradation pathway. Both S-N bond and C-S bond fragments became the initial attack and cleavage sites in the series of SAs. Ecotoxicity predictions indicated that most intermediates of SAs exhibited lower acute and chronic toxicity, especially acute toxicity, than the parent compounds. Assisted wet deposition to localize the active phase metal on the carrier surface allows easy target formation of single-atom cobalt catalysts (SA-Co-PCN), which could boost PMS to a 1O 2 -dominated system for efficient oxidation of typical micropollutants. The degradation behavior and ecotoxicology of sulfonamides in the SA-Co-PCN/PMS system were investigated in depth, revealing that most intermediates of sulfonamides exhibited lower acute and chronic toxicity, especially acute toxicity, than the parent compounds. This work provides a strategy for the development of facilely prepared single-atom catalysts and contributes to the development and application potential of PMS advanced oxidation technology for water pollution control. [Display omitted] • Targeted preparation of SA-Co-PCN can activate PMS efficiently. • PCN improved performance relatively less with initial Co atom addition above 8 wt%. • The K obs of SAs were SDZ, SIX, SMT and SMX in descending order. • Both S-N bond and C-S bond cleavage were the commonalities of SAs degradation pathway. • The toxicity of SAs degradation products was significantly reduced. [ABSTRACT FROM AUTHOR]

Highlights • The presence of LDH reduced the aggregation of PmPD and increased the specific surface area of LDH-PmPD. • The maximum adsorption capacity of LDH-PmPD was 588 mg/g for DCF. • The artificial aging (100 d) experiment indicated a good stability of LDH-PmPD. • LDH-PmPD could rapidly and efficiently remove diclofenac from actual medical wastewater. Abstract The emerging pollutant non-steroidal diclofenac sodium (DCF) has aroused increasing concerns, and the efficient removal of DCF from wastewater is becoming an urgent problem. In this study, the Mg/Al layered double hydroxide-Poly(m-Phenylenediamine) (LDH-PmPD) composite was synthesized, characterized and used for DCF adsorptive removal. The adsorption kinetics, isotherms as well as various influence factors, e.g., pH, humic acid, ions species and strength on the DCF removal were systematically investigated. The results showed that the presence of LDH weakened the accumulating density of PmPD and increased the specific surface area, which favored DCF adsorption on LDH-PmPD surface. LDH-PmPD exhibited a maximum adsorption capacity of 588 mg/g, which was superior to those of the conventional adsorbents. The artificial aging (100 d) experiment indicates a good stability of LDH-PmPD. Furthermore, due to the presence of electrostatic attraction, π-π electron-donor-acceptor interaction and N···HO hydrogen bonding between DCF and LDH-PmPD, the adsorption process was very effective in medical wastewater. The DCF removal efficiency reached nearly 100% within only 2 min in real medical wastewater using 0.125 g/L adsorbent. All these suggested that the prepared LDH-PmPD has great potential for DCF-contaminated water treatment. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Bismuth vanadate (BiVO 4) as a visible-light photocatalyst is always restricted by rapid photoexcited electron-hole recombination. Hence, the construction of charge transfer path is an essential strategy to establish an efficient photocatalytic system. Notably, the nitrogen doped carbon quantum dots (N-CQDs) exhibit potential for application in photocatalysis due to its high charge transfer capability and molecular oxygen activation ability. In this work, a Z-scheme BiVO 4 /N-CQDs/Cu 2 O system with enhanced molecular oxygen activation ability was constructed. Under the optimum condition, the BiVO 4 /N-CQDs/Cu 2 O composite showed 99.1% tetracycline hydrochloride (TC) removal efficiency under visible light irradiation in 60 min. The N-CQDs provide a potential driving force to reestablish the local electric field and lead to the construction of the Z-scheme BiVO 4 /N-CQDs/Cu 2 O system. And the excellent photocatalytic performance of this system was ascribed to the greatly enhanced molecular oxygen activation by contacting N-CQDs and the construction of Z-scheme system. Furthermore, the visible light absorption capability was obviously improved due to the fact that Cu 2 O provided multiple reflection of visible light and the N-CQDs act as a photosensitizer. Noteworthily, this study may help to further understand the function of N-CQDs in heterojunction and it could be expanded to design other photocatalysts. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Efficient catalytic OE composites were synthesized for persulfate activation. • The main radicals (SO 4 − and HO) on tetracycline degradation were identified. • The Co dispersion affect the catalytic performance of OE composites. Abstract The performance of pure cerium oxide (CeO 2) and cobalt oxide (Co 3 O 4) in advance oxidation processes cannot meet the growing pursuit of superior catalytic efficiency. In this study, efficient heterogeneous Co 3 O 4 /CeO 2 (OE) composites were fabricated by a calcination method to activate persulfate (PS) for tetracycline (TC) degradation. Results showed that OE-2/PS system exhibited the highest TC degradation efficiency (79%), while that of CeO 2 /PS system and Co 3 O 4 /PS system was only 22% and 14%, respectively. Co dispersion and turn over frequency demonstrated the superiority of OE-2 composite. Oxidative sulfate radicals (SO 4 −) and hydroxyl radicals (HO) generated in the process contributed to the efficient degradation of TC, which was proved by radical scavenging experiment and electron spin resonce experiment. In addition, the high stability and recycling ability of OE-2 composite were proved by the detection of leaching of Co and Ce ions and cycling test. [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Mg/Fe layered double hydroxide loaded with Magnetic(Fe 3 O 4) carbon spheres (MCs@Mg/Fe-LDHs) was firstly synthesized by a facile in-situ co-precipitation method to remove Pb(II) and Cu(II) pollution. To search the adsorption mechanism, MCs@Mg/Fe-LDHs was characterized by XRD, FTIR, XPS, TEM, and BET. There may exist surface complexation, precipitation, isomorphic substitution and physical adsorption in MCs@Mg/Fe-LDHs. The combination of those four types of reactions/interactions of metal ions with composite could improve the removal of Pb(II) and Cu(II). And the surface complexation was the main factor leading to the difference maximum adsorption capacity of Pb(II) (3.66 mmol/g) and Cu(II) (5.33 mmol/g). The adsorption kinetics and adsorption thermodynamics of MCs@Mg/Fe-LDHs for Pb(II) and Cu(II) could be better described by pseudo-second-order model and Langmuir model, respectively. The adsorption reaction was a spontaneous and endothermic process. Moreover, there existed competitive effect between Pb(II) and Cu(II) on the co-adsorption by MCs@Mg/Fe-LDHs. And the selectivity adsorption order of MCs@Mg/Fe-LDHs is as follows: Cu(II) > Pb(II) > Zn(II) > Ni(II) > Cd(II). Besides, in the real river water, the MCs@Mg/Fe-LDHs also exhibited stable adsorption capacity for Pb(II). In general, the MCs@Mg/Fe-LDHs has the potential for purification of water contaminated by Pb(II) and Cu(II). [ABSTRACT FROM AUTHOR]

Graphical abstract Abstract Metal-free g-C 3 N 4 is always limited by low surface area, rapid charge recombination and limited visible light absorption. In this study, novel porous nitrogen self-doped g-C 3 N 4 nanosheets were prepared by a combination of N self-doping and thermal exfoliation process. Compared to the bulk g-C 3 N 4 , N self-doped g-C 3 N 4 nanosheets possessed a high specific surface area of 74.79 m2 g−1, enhanced visible light absorption, improved photogenerated electron-holes separation, and prolonged lifetime of photogenerated charge carriers. As a consequence, N self-doped g-C 3 N 4 nanosheets exhibited higher photocatalytic activity for tetracycline (TC) degradation than that of bulk g-C 3 N 4 , N self-doped g-C 3 N 4 and g-C 3 N 4 nanosheets. It also exhibited remarkable stability and repeatability. The detailed photocatalytic mechanism was proposed. The midgap states created by N doping can significantly enlarge the visible light absorption, reduce the recombination and prolong the lifetime of photogenerated charge carries. The nanosheet construction can provide increased surface area, abundant active sites, short charge diffusion distance, fast separation and promoted redox abilities of photoexcited charge carries. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Novel In 2 S 3 /InVO 4 heterojunction prepared by a facile in-situ anion exchange method. • In 2 S 3 /InVO 4 exhibited much enhanced photocatalytic activity for TC degradation. • Anion exchange preserved the morphology and structure while enhancing the activity. • The photo-degradation is dominated by the hole and O 2 − while without OH radicals. • Enhanced charge separation and light absorption are obtained for In 2 S 3 /InVO 4. Abstract Semiconductor heterostructures have attracted extensive interest in photocatalytic degradation of antibiotic pollutants. In this study, a novel In 2 S 3 /InVO 4 heterojunction was prepared via a simple in-situ anion exchange method by reacting pre-synthesized InVO 4 microspheres with Na 2 S in an aqueous solution. The structures, morphologies and optical properties of the as-prepared samples were well characterized by XRD, SEM, EDS, TEM, XPS, N 2 adsorption–desorption, UV–Vis absorption spectra, PL, photocurrent and electrochemical impedance spectroscopy. Benefiting from the enlarged visible light response and the formation of heterostructure, the as-prepared In 2 S 3 /InVO 4 microspheres exhibit significantly promoted photocatalytic performance for the degradation of tetracycline (TC) under visible-light illumination. The optimum photocatalytic efficiency of In 2 S 3 /InVO 4 composite was almost 2.26 and 11.71 times higher than that of In 2 S 3 and InVO 4 , respectively. It also exhibited remarkable stability and repeatability. Radical trapping experiment and electron spin resonance results indicate that h+ and O 2 − are the main active species in the reaction system, and the role of OH can be ignored. The detailed photocatalytic mechanism is also proposed. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Excellent properties and recent advances of ZnIn 2 S 4 micro/nano-structures are emphasized. • The optimizing strategies for ZnIn 2 S 4 photocatalyst are explicated. • Favorable performances in energy conversion and pollutants removal are summarized. • Profound mechanisms for the catalytic activity improvement are discussed. • Current challenges and prospects of ZnIn 2 S 4 and ZnIn 2 S 4 -based photocatalysts are proposed. Abstract Solar light is an ideal energy source to overcome the crisis of energy shortage and severe environment problems. In the past decades, photocatalysis technology has aroused tremendous interests. As a layered structure ternary metal chalcogenide, zinc indium sulfide (ZnIn 2 S 4) is a typical visible-light-responsive photocatalyst which has a tunable band gap for wider light absorption. Recently, ZnIn 2 S 4 has been widely utilized in photocatalytic applications. Its photocatalytic performance is largely dependent on its structure, morphology and optical characteristics. This review first presented the crystal properties, the morphology characteristics as well as the electronic and optical properties of ZnIn 2 S 4. Then, recent advances in the preparation and growth mechanisms of ZnIn 2 S 4 micro/nano-structures were summarized. Furthermore, the modification methods for constructing efficient ZnIn 2 S 4 -based photocatalysts and their applications in hydrogen evolution, CO 2 reduction and pollutants removal were also emphasized in this review. Finally, the current challenges and the crucial issues of ZnIn 2 S 4 and ZnIn 2 S 4 -based photocatalysts were proposed. It is expected that such a critical review could bring a better understanding of ZnIn 2 S 4. [ABSTRACT FROM AUTHOR]

The catalytic performances of magnetic Ni x Fe 3−x O 4 catalysts in persulfate (PS) activation for tetracycline (TC) degradation are first investigated. In this study, Ni x Fe 3−x O 4 catalysts with variable compositions (x = 0.2, 0.6 and 1.0) were synthesized. The physical and chemical characteristics of Ni x Fe 3−x O 4 catalysts were investigated systematically. Ni x Fe 3−x O 4 catalysts have sheet-like morphology and spinel type structure. In Ni x Fe 3−x O 4 /PS system, sulfate radical (SO 4 − ) and hydroxyl radicals (HO ) produced by PS activation degraded TC efficiently. In the comparation of different Ni x Fe 3−x O 4 catalysts, Ni 0.6 Fe 2.4 O 4 presented superior catalytic activity performance. The optimum degradation rate in 86% was obtained at Ni 0.6 Fe 2.4 O 4  = 350 mg/L, PS = 42.0 µM and pH = 7 after 35 min reaction. The main radicals (SO 4 − and HO ) were identified by scavengers and the electron spin resonance (ESR) experiment. Meanwhile, possible activation and degradation mechanism were analyzed thoroughly. The high catalytic efficiency and short degradation period of Ni 0.6 Fe 2.4 O 4 catalyst indicate that it has great potential in TC wastewater disposal and environmental protection. [ABSTRACT FROM AUTHOR]

The high visible light active photocatalysts of Ag@AgI/CdWO 4 (AICW) were synthesized via in situ deposition–precipitation and photoreduction methods. The physicochemical properties of crystal phases, morphologies, chemical compositions, optical properties and so on were characterized via several techniques. The results shown that the interface interaction between CdWO 4 (CW) nanorods and Ag@AgI (AI) particles would enhance the visible light trapping, improve the surface area, promote the separation and transfer of photogenerated charge carrier and prolong the photoelectron lifetime. The AICW–3 with considerable reusability exhibited the optimum synergism of visible light photoactivity towards rhodamine B (RhB) and tetracycline (TC) degradation, in which the RhB and TC degradation ratio is 99.3% (24 min) and 77.0% (20 min), respectively, and the photocatalytic rate is 2.43 and 2.61 times that of AI, respectively. Furthermore, the free radical capture and electron spin resonance (ESR) experiments indicated that the O 2 − , h + and OH species were the main radicals for RhB and TC degradation. Accordingly, the possible mechanisms of transfer and separation of photoinduced carriers as well as the generation of radicals for RhB and TC decomposition under visible light irradiation were proposed to lead the further improvement in environment remediation. [ABSTRACT FROM AUTHOR]

In this study, zero valent iron (ZVI) activated peroxymonosulfate (PMS) as novel technique (i.e. ZVI-PMS technology) was employed to enhance sludge dewatering. In optimal sludge dewatering conditions of ZVI and KHSO 5 dosages, the specific resistance to filtration (SRF) was reduced by 83.6%, which was further decreased to 90.6% after combination of ZVI-PMS with thermal treatment at 50 °C (i.e. ZVI-PMS-T technology). Subsequently, the ESR spectrum and quenching tests demonstrated that OH , rather than SO 4 − , was predominant radicals in ZVI-PMS conditioning. Thereafter, the variation of physicochemical properties and the distributions and compositions of extracellular polymeric substances (EPS) were further investigated to uncover the influence of these techniques on sludge bulk properties. The results indicated that sludge particles were disintegrated into smaller particles and surface charges were neutralized, sludge flowability were elevated obviously after treatments. In ZVI cycle experiment, the high dewatering efficiency was maintained by ZVI-PMS and ZVI-PMS-T pretreatment. [ABSTRACT FROM AUTHOR]

Artificial Z-scheme photocatalyst can not only reduce the recombination of photogeneraged electron–holepairs, but also retain prominent redox ability. In this study, direct solid-state dual Z-scheme WO 3 /g-C 3 N 4 /Bi 2 O 3 photocatalyst was successfully synthesized by one step co-calcination stratage using tungstic acid, melamine and bismuth (III) nitrate pentahydrate as the precursors. Surface, morphological, and structural properties of the resulting materials were comprehensive characterized by XRD, XPS, SEM, TEM, UV–vis diffuse reflection spectroscopy, BET surface areas, photoluminescence and ESR analysis. The WO 3 /g-C 3 N 4 /Bi 2 O 3 composite exhibited superior photocatalytic activities for tetracycline degradation than that of pure g-C 3 N 4 , WO 3 , Bi 2 O 3 and their binary composites under visible light irradiation. The enhanced photocatalytic performance of WO 3 /g-C 3 N 4 /Bi 2 O 3 composite can be ascribed to improved visible light absorption, increased surface area and enhanced separation efficiency of photo-generated electron-hole pairs. In addition, the photocatalyst exhibits high stability and reusability. On the basis of the results, a novel direct solid-state dual Z-scheme photocatalytic mechanism was also proposed. [ABSTRACT FROM AUTHOR]

Oily scum, a hazardous by-product of petroleum industry, need to be deposed urgently to reduce environmental risks. This paper introduces catalytic wet persulfate oxidation (CWPO) process in the treatment of oily scum to realize risk relief. Under the activation of heat and Fe 2+ , persulfate (PS) was decomposed into sulfate radicals and hydroxyl radicals, which played a major role on the degradation of petroleum hydrocarbons. The effects of wet air oxidation (WAO) and CWPO process on the degradation of oily scum were compared. In CWPO process, the total petroleum hydrocarbons (TPHs) content of oily scum was decreased from 92.63% to 16.75%, which was still up to 70.19% in WAO process. The degradation rate of TPHs in CWPO process was about 3.38 times higher than that in WAO process. The great performance of CWPO process was also confirmed by elemental analysis, which indicated that the C and H contents of oily scum were reduced significantly by CWPO process. These results indicated that CWPO process has high potential on the degradation of oily scum for environmental protection. [ABSTRACT FROM AUTHOR]

Biomass-derived bio-oil cannot be applied directly in diesel engines due to several poor fuel properties such high viscosity and instability. Emulsification could overcome the disadvantages of bio-oil. In this study, bio-oil emulsified with diesel was combusted in a DI diesel engine, and the effects of bio-oil compositions on the engine performance and emissions were investigated. Crude bio-oil has aging and instability problems, which could cause inconsistencies in the results. Synthetic bio-oil was used to avoid the limitations posed by crude bio-oil. Synthetic bio-oil was fractioned into three categories (hydroxyl compounds, aldehydes and sugars), and the corresponding emulsions were prepared. Compared with diesel, the brake-specific fuel consumption (BSFC) and brake-specific energy consumption (BSEC) were increased, and the brake power remained almost unchanged for the emulsions. For the exhaust emissions, CO and smoke emissions were decreased, while CO 2 emissions were increased. The emulsions derived from the aldehydes and hydroxyl compounds reduced NO x emissions, whereas emulsions derived from sugars and the whole bio-oil increased NO x emissions. The results indicated that the aldehydes and hydroxyl compounds in bio-oil were more desirable for clean combustion than sugars. The hydroxyl compounds could result in the largest emissions reductions due to the presence of OH radicals. [ABSTRACT FROM AUTHOR]

The Yb 3+ /Tm 3+ codoped flower−like tetragonal In 2 S 3 photocatalysts were synthesized through a hydrothermal route, and the crystal phases, morphologies, chemical compositions and optical properties were characterized. The results shown that the doping with Yb 3+ /Tm 3+ did not significantly change the crystallinity of In 2 S 3 , but induced the generation of intermediate energy states for efficient charge separation. The Yb 3+ /Tm 3+ codoped In 2 S 3 presented a significant enhancement of photoactivity towards chromium (VI) reduction and rhodamine B oxidation from UV to NIR light. The best photocatalytic synergism was obtained for the sample with the mole ratio of In 3+ :Yb 3+ :Tm 3+ at 159:40:1, in which the chromium (VI) reduction efficiency was 97.9% (NIR, 100 min), 99.3% (vis, 10 min) and 98.3% (UV, 10 min), while the rhodamine B degradation efficiency was 98.4% (NIR, 100 min), 97.3% (vis, 14 min), and 96.3% (UV, 14 min). The favorable NIR photoactivity was mainly attributed to the upconversion mechanism via energy level transition of Yb 3+ /Tm 3+ . Under the full−spectra−light irradiation for 6 min and 7 min, the removal efficiency of chromium (VI) and rhodamine B could reach to 99.4% and 94.8%, the corresponding rate constant was 2.17 and 5.60 times of pure In 2 S 3 , respectively. The improved photocatalytic efficiency might be attributed to the enhanced light absorption and favorable charge separation resulted from the intermediate energy states and/or sulfur vacancies. In addition, the free radical capture and electron spin resonance experiments were also performed to determined the role of O 2 − and h + species during photocatalytic oxidation process. [ABSTRACT FROM AUTHOR]

The disposal of excessive activated sludge by advanced oxidation processes (AOP) to avoid its potential environmental risk has received extensive attention. As an efficient and clean oxidant, hydrogen peroxide (H 2 O 2 ) has been used widely in AOP. In H 2 O 2 based AOP, strong oxidative hydroxyl radical (HO ) produced by different kinds of activation methods plays an important role in sludge treatment for sludge reduction, recycling and risk relief. This review summarizes current studies and breakthroughs of H 2 O 2 based AOP in sludge treatment. Meanwhile, the possible mechanisms of H 2 O 2 based AOP in sludge dewatering, sludge minimization, anaerobic digestion and the removal of pollutants are clarified systemically. Furthermore, the cost estimation of H 2 O 2 based AOP in sludge treatment is materialized. Finally, the possible focus of future study in sludge treatment via H 2 O 2 based AOP is present. This review can provide a theoretical basis for applying H 2 O 2 based AOP in sludge reduction, recycling and risk relief. [ABSTRACT FROM AUTHOR]

The highly visible light active Sn 0.215 In 0.38 S/reduced graphene oxide (SIS/RGO) composites with hierarchical porous were prepared by a facil solvothermal in-situ growth method for rhodamine B (RhB) removal coupling adsorption with photocatalysis. The morphology, composition and photocurrent response of the adsorptive photocatalysts were systematically characterized. The investigation results showed that both adsorption and photocatalytic processes were affected by pH, ionic strength and so on. The RhB adsorption process complied with pseudo-second order kinetics equation and Langmuir isotherm model, and the SIS/RGO-2.5% showed the optimum adsorption-photocatalytic performance. The maximum adsorption capacity of SIS/RGO-2.5% was 173.97 mg·g −1 mainly attributing to the electrostatic attraction, π − π interaction and surface complexation. Due to efficient mass transfer efficiency, dye self-sensitization and effective transfer of photogenerated carriers, the photodegradation efficiency of RhB over SIS/RGO-2.5% was as high as 96.25% under visible light irradiation for 25 min and the corresponding reaction rate constant is 3.98 times of Sn 0.215 In 0.38 S. The results of free radical capture and electron spin resonance experiments indicated that the O 2 − and h + were the main active species attacking RhB. Furthermore, cyclic experiments showed the considerable reusability and stability of photocatalysts for the RhB degradation. [ABSTRACT FROM AUTHOR]

In this study, a novel N-CQDs/Bi 2 WO 6 was synthesized through a facile hydrothermal method. Multiple techniques were applied to investigate the structures, morphologies, optical and electronic properties and photocatalytic performance of as-prepared samples. The results indicated that the hybrid materials were formed with N-CQDs attached on the surface of sphere-like Bi 2 WO 6 . The photocatalytic activity of N-CQDs/Bi 2 WO 6 materials was evaluated sufficiently by using tetracycline (TC) as target organic pollutant. N-CQDs/Bi 2 WO 6 -5 displayed superior photocatalytic efficiency with nearly 97% removal of TC in 25 min and 86.37% mineralization in 90 min. The degradation reaction coefficient (kobs) was approximately two times higher than pure Bi 2 WO 6 as a result of the synergistic effects of N-CQDs and Bi 2 WO 6. Increased light harvesting capacity, excellent electron transfer ability and improved molecular oxygen activation ability were obtained in N-CQDs/Bi 2 WO 6 hybrid materials caused by N-CQDs. The present study demonstrated that N-CQDs modification was an effective way to improve photocatalytic efficiency, which can be extended to a general strategy for other semiconductors. The study indicated that novel N-CQDs/Bi 2 WO 6 has a great potential for rapid and efficient treatment of organic pollutants in water. [ABSTRACT FROM AUTHOR]

The photocatalytic performance of the star photocatalyst g-C 3 N 4 is restricted by the insufficient solar light absorption, low surface area and the fast recombination of photogenerated electron-hole pairs. The present study developed a facile in situ method to construct hexagonal boron nitride (h-BN) decorated g-C 3 N 4 metal-free heterojunction with the aim to greatly enhance the surface area and promote the charge separation. The physical, chemical and optical properties of the resulted samples were thoroughly characterized. The photocatalytic performance of h-BN/g-C 3 N 4 composites were evaluated under visible light irradiation using antibiotic tetracycline (TC) and rhodamine B (RhB) as target pollutants. Results showed that h-BN/g-C 3 N 4 composites exhibited much higher photocatalytic activity than pure g-C 3 N 4 and h-BN. The optimum photocatalytic efficiency of BC-3 sample for the degradation of TC was about 2.3 and 60.3 times higher than that of individual g-C 3 N 4 and h-BN, respectively. Meanwhile, it was about 7.3 and 11.8 times higher than that of individual g-C 3 N 4 and h-BN for RhB degradation, respectively. The enhanced photocatalytic activity of h-BN/g-C 3 N 4 composite is mainly attributed to the larger surface area and the unique physicochemical properties of h-BN nanosheet which acts as a promoter for photoexcited holes transfer. This work indicates that the metal-free h-BN/g-C 3 N 4 hybrid photocatalyst is a promising material in wastewater control. [ABSTRACT FROM AUTHOR]

Genetically modified Bacillus thuringiensis ( Bt ) crops, which have been widely used in agricultural transgenic plants, express insecticidal Cry proteins and release the toxin into soils. Taking into consideration the environmental risk of Cry proteins, biosurfactant—rhamnolipids were applied to desorb Cry proteins from soil environment, which has not been elucidated before. Quartz crystal microbalance with dissipation (QCM-D) was used in this article to investigate the adsorption and desorption behaviors of Cry1Ac on SiO 2 surface (model soil). Results showed that patch-controlled electrostatic attraction (PCEA) governed Cry1Ac adsorption to SiO 2, and the solution pH or ionic strength can affect PCEA. The adsorption kinetics could be fitted by the pseudo-second-order model, and the adsorption isotherm was fitted to Langmuir model with correlation coefficients higher than 0.999. The desorption characteristics of Cry1Ac from SiO 2 were assessed in the presence of mono-rhamnolipid, di-rhamnolipid or complex-rhamnolipid. Mono-rhamnolipid exhibited the most significant positive effect on desorption performance. With a complete removal of Cry1Ac reached when mono-rhamnolipid concentration was up to 50 mg L −1 . Additionally, the desorption was enhanced at alkaline pH range, and Cry1Ac can be completely and rapidly desorbed by rhamnolipids from SiO 2 at ionic strength of 5 × 10 −2 M. [ABSTRACT FROM AUTHOR]

The application of graphene oxide (GO) has attracted increasing concerns in the past decade regarding its environmental impacts, except for the impact of GO on a metal-contaminated soil system, due to its special properties. In the present work, the effects of GO on the migration and transformation of heavy metals and soil bacterial communities in Cd-contaminant soil were systematically evaluated. Soil samples were exposed to different doses of GO (0, 1, and 2 g kg −1 ) over 60 days. The Community Bureau of Reference (BCR) sequential extraction procedure was used to reflect the interaction between GO and Cd. Several microbial parameters, including enzyme activities and bacterial community structure, were measured to determine the impacts of GO on polluted soil microbial communities. It was shown that Cd was immobilized by GO throughout the entire exposure period. Interestingly, the structure of the bacterial community changed. The relative abundance of the major bacterial phyla (e.g., Acidobacteria and Actinobacteria ) increased, which was possibly attributed to the reduced toxicity of Cd in the presence of GO. However, GO exerted an adverse influence on the relative abundance of some phyla (e.g., WD272 and TM6 ). The diversity of bacterial communities was slightly restricted. The functional bacteria related to carbon and the nitrogen cycling were also affected, which, consequently, may influence the nutrient cycling in soil. [ABSTRACT FROM AUTHOR]

Water pollution is one of the forefront environmental problems. Due to the simplification, flexibility and low cost, the adsorption becomes one of the most fashionable technology and the exploitation of adsorbents has drawn greatly attention. In this study, a novel magnesium silicate-hydrothermal carbon composite (MS-C) was synthesized by facile hydrothermal carbonization and used to remove the cadmium (Cd(II)) and methylene blue (MB) from wastewater. It was shown that the porous and lump-like magnesium silicate (MS) was decorated with multiple hydrothermal carbon (HC) via the C O Si covalent bonding. Further, the adsorption behavior of Cd(II) and MB based on the MS, HC, and MS-C were systematically investigated. The equilibrium data of both Cd(II) and MB were fitted well with Langmuir model. Compared to pure MS and HC, the adsorption capacity of composite was significantly improved, accompanied by the maximum adsorption capacity of 108 mg/g for Cd(II) and 418 mg/g for MB, respectively. In the Cd(II)–MB binary system, the adsorption of Cd(II) was favored in comparison with that of MB. The removal of Cd(II) was mainly ascribed to electrostatic attraction and the ion exchange interaction. Meanwhile, the adsorption of MB onto adsorbent was driven by the electrostatic attraction, π-π interaction and hydrogen bond. In view of these empirical results and real water treatment, the environmental friendly and low-cost MS-C holds a potential for separate or simultaneous removal of Cd(II) and MB in practical applications. [ABSTRACT FROM AUTHOR]

Proper treatment of waste-activated sludge (WAS) involves three pivotal processes, dewatering, anaerobic digestion, and pollutants removal, which need to be re-assessed urgently. Although many traditional sludge treatments have been developed, it is prudent to enhance the efficiency of sludge treatment using multifunctional, flexible, and environmentally friendly surfactants. With regard to sludge dewatering, surfactants can weaken the binding interaction between sludge flocs and promote the dissolution of extracellular polymeric substances (EPSs), resulting in the release of bound water. Using surfactants in anaerobic digestion promotes the release of enzymes trapped in sludge and improves the activity of enzymes during hydrolysis. Owing to their characteristic encapsulation of hydrophobes into self-assembled aggregates (micelles), surfactants can form host-guest complexes with polycyclic aromatic hydrocarbons (PAHs). Additionally, surfactants can enhance the desorption of heavy metals and prevent the emergence of heavy metal residue. This review summarizes the current surfactant-based sludge treatment technologies according to their roles in sludge disposal solutions. Then, possible mechanisms of surfactants in sludge dewatering, anaerobic digestion, and the removal of organic pollutants and heavy metals are analysed systemically. Finally, changes to sludge treatment via the aid of surfactants are highlighted. This review presents the comprehensive advances in the use of surfactants in WAS reduction, recycling, and risk relief, underscoring their roles in increasing economic efficiency and ensuring environmental quality. [ABSTRACT FROM AUTHOR]

The reduced graphene oxide decorated NH 2 -MIL-68(Al) (RGO/NMA) is synthesized via one-pot solvothermal process and systematically characterized for the congo red (CR) removal from single and binary water with cationic dyes. The characterization results show that the surface area of negatively charged RGO/NMA is significantly enhanced by the introduction of reduced graphene oxide (RGO). The CR adsorption is investigated as a function of contact time, initial CR concentration, temperature, pH and ionic strength. It shows that the maximum CR adsorption capacity of RGO/NMA (473.93 mg/g) is 121% and 1337% higher than NH 2 -MIL-68(Al) (NMA) and RGO, respectively. The adsorption dynamic analysis shows that the Pseudo-second-order model presents the best fitting to CR adsorption compared with Pseudo-first-order and Elovich model. The adsorption rate-limited step is successively controlled by film-diffusion and intra-particle diffusion according to the applicability measurement of intra-particle diffusion, boyd's film-diffusion models and external mass transfer plots. Based on the suitability of isotherm models, the CR adsorption process can be described in order of Langmuir > Temkin > Freundlich > Hill. The adsorption mechanism involved the electrostatic attraction, π–π dispersion interaction and hydrogen bonds for the spontaneously exothermic adsorption process are indentified using the three-dimensional excitation-emission matrix (3D-EEM) fluorescence spectrum The synergistic effect occurs in the simultaneous removal CR and cationic from water. The RGO/NMA has the excellent reusability and the resource utilization of CR loaded RGO/NMA as photocatalyst for Cr(VI) reduction under visible light irradiation is highly feasible. [ABSTRACT FROM AUTHOR]

As a fascinating conjugated polymer, graphitic carbon nitride (g-C 3 N 4 ) has been the hotspot in the materials science as a metal-free and visible-light-responsive photocatalyst. Pure g-C 3 N 4 suffers from the insufficient sunlight absorption, low surface area and the fast recombination of photo-induced electron-hole pairs, resulting in low photocatalytic activity. Element doping is known to be an efficient method to tune the unique electronic structure and band gap of g-C 3 N 4 , which considerably broaden the light responsive range and enhance the charge separation. This review summarizes the recent progress in the development of efficient and low cost doped g-C 3 N 4 systems in various realms such as photocatalytic hydrogen evolution, reduction of carbon dioxide, photocatalytic removal of contaminants in wastewater and gas phase. Typically, metal doping, nonmetal doping, co-doping and heterojunction based on doped g-C 3 N 4 have been explored to simultaneously tune the crystallographic, textural and electronic structures for improving photocatalytic activity by enhancing the light absorption, facilitating the charge separation and transportation and prolonging the charge carrier lifetime. Finally, the current challenges and the crucial issues of element doped g-C 3 N 4 photocatalysts that need to be addressed in future research are presented. This review presented herein can pave a novel avenue and add invaluable knowledge to the family of element doped g-C 3 N 4 for the develop of more effective visible-light-driven photocatalysts. [ABSTRACT FROM AUTHOR]

[Display omitted] • CN was firstly used for periodate activation under visible-light irradiation. • UCN/PI/Vis synergistically accelerated degradation of various antibiotics. • 1O 2 and iodate radical played a dominant role in TC degradation, followed by O 2 −. • Electron transfer occurs in a concerted process where PI as an electron scavenger. • Photocatalytic reaction mechanism and path of photogenerated charges were studied. Periodate (PI)-based advanced oxidation processes (AOPs) have drawn growing attention in an effort to alleviate pollutants issues in the aqueous environment. Different from previous use of ultraviolet light or metal catalysts, this study proposes a novel system for the visible-light-assisted activation of PI via metal-free polymeric carbon nitride (CN). The best catalytic effect was achieved by CN synthesized from urea (UCN). Effective charge separation predominately caused kinetic increase in photocatalytic degradation, where interfacial electron transfer in UCN/PI/Vis system occurred in the synergistic process. UCN generated photogenerated electrons-hole under visible light irradiation. The organic pollutant acted as an electron donor. PI could effectively act as an electron capture agent and inhibit the complexation of charge carriers. The combination of PI-based AOP and photocatalysis greatly increased the degradation of pollutants through photocatalysis, achieving the effect of 1 + 1 > 2. The tetracycline (TC) effectively underwent nearly 100 % removal within 10 min and the corresponding k obs attained 0.40839 min−1. Besides, outstanding catalytic performance in a broad range of pH (2.99–11.01) was confirmed. Meanwhile, the UCN/PI/Vis system demonstrated favorable immunity to common wastewater components, good stability, and reusability. The prominent active species for TC degradation were singlet oxygen (1O 2) and iodate radical (IO 3 ·, IO 4 ·), followed by superoxide radicals (O 2 −). This study establishes a precedent for visible-light-induced activation of PI by UCN, interfacial electron transfer occurs in a synergistic process, and greatly accelerated photocatalytic oxidation is accomplished with PI acting as an electron scavenger. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel Cu-containing zeolites activated percarbonate system was constructed. • Carbonate-mediated triplet-excited state of TC promoted degradation process. • The roles of carbonate ions and multiple ROSs were explored. • The practicability of Cu/ZSM5/SPC/vis process was satisfactory. The removal of tetracycline (TC) via various advanced oxidation processes (AOPs) under visible light has been widely investigated. However, the photosensitive effect of TC on its removal has been mostly neglected. In this work, the photosensitization of TC is explored by a novel catalytic system, Cu-containing zeolite (Cu/ZSM5) activation on sodium percarbonate (SPC) under visible light irradiation. Experimental results indicated that the Cu/ZSM5/vis/SPC process could achieve 100 % removal of TC within 40 min (k obs = 0.099 min−1), while only removal of 58.1 % was achieved under dark conditions (k obs = 0.016 min−1). It was confirmed for the first time by phosphorescence spectroscopy that carbonate ions (CO 3 2–) could induce TC to be excited into triplet states (3TC*) under visible light, synergistically forming the carbonate radicals (•CO 3 −). Besides, the CO 3 2– reacted with hydroxyl radical (•OH) derived from the heterogeneous Fenton-like pathway by Cu/ZSM5, leading to the generation of multiple kinds of reactive oxygen species (•OH, •CO 3 −, •O 2 −, and 1O 2), which further together contribute to the TC removal. This study does not only present a novel strategy via Cu-containing zeolite with SPC to remove TC but also found that TC acts as both a sensitizer and oxidized substrate. [ABSTRACT FROM AUTHOR]

[Display omitted] • First preparation of Bi 2 S 3 quantum dots (QDs) decorated-MIL-53 (Fe) composites (BM) by an easy chemical synthesis strategy. • The BM/persulfate/Visible light system was designed to effectively degrade ciprofloxacin in water. • The BM can facilitate the separation of photogenerated electron-hole pairs. • Electron transfer between QDs and MIL-53(Fe) contributes to the formation of oxygen vacancies. • Bi 2 S 3 QDs decorated with MIL-53 (Fe) for excellent repeatability and stability. In recent years, concurrent photocatalysis-persulfate activation (CPPA) has emerged as a potential method for antibiotic removal. A highly active and stable catalyst is the prerequisites for the development of CPPA technology. Herein, Bi 2 S 3 quantum dots (QDs) decorated MIL-53 (Fe) hybrids were synthesized for the first time by a simple chemical synthesis strategy and used for antibiotic degradation in the CPPA system. The energy band structure and optical properties show that BM has a narrower forbidden bandwidth, higher carrier separation, and transport efficiency compared to the original MIL-53(Fe). It also promotes the O 2 transfer and makes the BM rich in oxygen vacancy (Ov), which becomes a bridge to connect photocatalysis and SR-AOPs. The BM-5/PS/vis system degraded over 97.4 % of the ciprofloxacin in 15 min and remained effective in the presence of common interfering substances or over a wide pH range. The quenching and trapping experiments indicate the dominance of superoxide radicals and singlet oxygen in the degradation process. The simultaneous activity of free radical and non-free routes could be responsible for the improved antibiotic degradation efficiency. This work provides a facile strategy in surface modification to improve the physicochemical properties of MIL-53(Fe) and demonstrates the catalytic role of BM in the CPPA system. [ABSTRACT FROM AUTHOR]

Perovskite-type structure materials have attracted considerable attention in the field of solar cell and photocatalysis. In this study, novel plasmonic Bi nanoparticles and BiOCl sheets co-decorated ZnSn(OH) 6 (ZSH) with various morphologies (hence exposure facets) was successfully synthesized via one-pot precipitation, hydrolysis and UV-photoreduction process. The as-obtained materials were characterized by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, X-ray photoelectron spectroscopy, ultraviolet–visible diffuse reflection spectroscopy and photocurrent-time measurement. Results indicated that the cubic, 14-facets polyhedral and octahedral ZSH were decorated by plasmonic Bi particles and BiOCl sheets, which improved visible-light absorption, charge carrier separation and migration performance. Compared with pure ZSH, the composites showed enhanced photocatalytic activity, with the highest photocatalytic performance achieved by the octahedral ZSH decorated by Bi and BiOCl (i.e., ZSH-3-Bi). The photo-degradation rate of ZSH-3-Bi was about 81 times higher than that of pure octahedral ZSH. This phenomenon was mainly ascribed to the surface plasmon resonance effect for visible light absorption, the exposed {111} facets relative to other facets of octahedral ZSH, and the improved charge carrier separation efficiency due to the strong interfacial interaction of three components. The radical and hole trapping, and electron spin resonance spin-trap experiments verified that the OH, O 2 − and h + were the main reactive species in this system, which were responsible for the decoloration and part mineralization of the RhB molecules. Therefore, this work provides new insights into the in situ fabrication of plasmonic Bi-based photocatalyst with facet-oriented polyhedron for full utilization of solar energy and wastewater treatment. [ABSTRACT FROM AUTHOR]

Sparked by growing pollution issues, research aiming at a better harvesting of solar energy in photocatalysts for environmental remediation has been thriving. In this study, a novel mixed valence state of Co 2.67 S 4 nanoparticles with full-spectrum-responsive photocatalytic activity had been fabricated via a facile solvothermal route. The as-synthesized samples were systematically characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and UV–vis-NIR diffuse reflection spectroscopy (UV–vis-NIR DRS). The photocatalytic performance of as-obtained samples had been investigated by the degradation of methylene blue (MB) in aqueous solution. The Co 2.67 S 4 nanoparticles with the particle size of 5–20 nm could degrade MB with the efficiency of 64%, 84% and 68% under the UV light, visible light and near-infrared light exposure, respectively. Furthermore, a possible photocatalytic mechanism toward the near-infrared region had been proposed to be that the Co 2+ /Co 3+ redox couple played vital parts in the photocatalytic activity of Co 2.67 S 4 . This study provides a novel full solar spectrum-responsive photocatalyst for solar-light utility and environmental remediation. [ABSTRACT FROM AUTHOR]

Photoactive metal-organic frameworks (MOFs) have lately emerged as a class of crystalline porous materials, which provides an advanced platform to develop catalysts for the photocatalytic decolorization of wastewater. Controllable integration of pure MOFs into other active materials creates fabrication protocols for new multifunctional hybrids with superior photocatalytic properties for dye degradation into individual components, and the calcination of transition-metal MOF precursors affords a convenient and practical route for preparation of nanosized photocatalysts with novel structures and good purity. Although the application of pure MOFs for organic pollutant decomposition has been reviewed previously, there have been significant advances in diverse MOF-based composites and their derivatives for dye degradation, which have rarely been reviewed. This review aims to fill this gap and discuss the various influencing factors, the reaction kinetics, and mechanisms of dye degradation, considering the period from 2014 to 2016. Finally, the challenges and outlooks for dye decomposition by MOF-based materials are suggested. [ABSTRACT FROM AUTHOR]

The dike-pond system was a form of ecological engineering that was a component of successional dikes and ponds along the banks of the Pengxi River in the drawdown zone (DDZ) of the Three Gorges Reservoir (TGR). The application of science-based evaluation system was appropriate for the flows of emergy in this agricultural ecosystem. The Emergy Analysis (EmA) has the ability to transform different types of inputs to a common form to allow meaningful comparisons across different systems. This study made use of the emergy analysis that assessed two different types of farming methods in the DDZ of the TGR. One method was planning crops in a dike-pond system (model I), and the other method was conventional agriculture (model II). In addition, the Exergies of both yields of agriculture methods were calculated, and the Exergy and Emergy Density (ED) were combined to explore the quality of these methods. The results showed that the two models relied on different resources. The ED yield of both models were similar, but the emergy investment of model II was greater than that of model I. Model II also used less renewable energy input to the agricultural systems than model I. The agricultural emergy sustainability index (AESI) of model I system (AESI = 2.4 > 1) was greater than that of model II system (AESI = 0.5 < 1), which indicated that the sustainable development of model I was stronger than that of model II in the DDZ of the TGR. The ratio Exergy/Emergy density ( R ex/em ) in the two models of different agricultural system were 121.52 × 10 −3 J/sej (Model I) and 24.19 × 10 −3 J/sej (model II). Model I was greater than model II, and the result intimated that the model I agricultural system was a new method in the DDZ, but it was older and closer to the steady state than model II. The Emergy and Exergy analysis certifies that model I has a more acceptable and more sustainable development potential and is more stabilized in the DDZ of the TGR. [ABSTRACT FROM AUTHOR]

Considering self-heating and hazardous gaseous emission, the safety of wood pellets storage has become one of the important aspects for woody biomass utilization. In this study, the emissions of aldehydes/ketones were analyzed by high performance liquid chromatogram (HPLC). The properties of pellets stored in semi-closed tanks with different temperatures and relative humidity (RH) were also investigated. The emissions of aldehydes and ketones from pellets were increased with raising temperature and RH during storage, while the pellets’ physical properties (dimension, density, Meyer hardness and moisture content) were reduced, except for 70% and 90% RH runs. The fatty acids compositions were extracted from both the surface and the inner part of pellets, which were analyzed by gas chromatography–mass spectrometry (GC–MS). The interaction between pellets’ physical properties variation and unsaturated fatty acid oxidation was revealed by the investigation of differences of extracted unsaturated fatty acids concentration between the surface and the inner part of pellets, which affected the aldehydes and ketones emissions. [ABSTRACT FROM AUTHOR]

Waste activated sludge (WAS) is difficult to be dewatered due to the highly water bounded in sludge flocs, and the extracellular polymeric substances (EPS) was the major factor affecting sludge dewatering performance. In this study, the hybrid process of electrolysis/electrocoagulation and zero-valent iron activated persulfate oxidation (EZP) showed a significant synergetic effect in enhancing municipal sludge dewaterability, and has the potential for enhancing industrial sludge dewaterability. The optimal dewatering conditions for municipal sludge were voltage 40 V and 4.15 g/L Na 2 S 2 O 8 when zero-valent iron induced electrodes were applied. After EZP pretreatment, the municipal sludge specific resistance to filtration (SRF) and capillary suction time (CST) decreased by 87.4% and 49.1% respectively. The effects of EZP pretreatment on zeta potential, EPS property, viscosity and dewaterability of different sludge were analyzed to unravel the underlying mechanism of sludge conditioning. Results showed that the EZP oxidation was capable to effectively disrupt the EPS, crack the entrapped cells, and degrade the protein-like substances, reducing the viscosity and negative zeta potential, releasing bound water inside EPS and cells and thus improving sludge dewaterability. According to the analysis of Three-dimensional excitation emission matrix (3D-EEM), the EZP technology greatly decomposed tryptophan and aromatic protein-like substances in EPS. Scanning electron microscope (SEM) analysis further revealed that the disrupted EPS and cells were coagulated after EZP conditioning and reinforced sludge dewatering. The preliminary economic analysis showed that the optimized EZP was economically favorable. [ABSTRACT FROM AUTHOR]

Pelletization has been widely used for mass and energy densification of biomass. As the demand for pellets increases, the conventional raw materials will be insufficient. In this study, the feasibility of sludge mixed with biomass pellets as a solid fuel was researched. Sludge mixed pellets and pure biomass pellets were investigated to evaluate the energy consumption and pellet properties, including proximate analysis, moisture adsorption, pellet density, Meyer hardness, volume expansion, higher heating value and combustion characteristics. The results showed that sludge mixed pellets had reduced energy input, increased hardness, decreased moisture absorption rate and improved combustion characteristics compared with pure biomass pellets. However, the increased ash content of sludge mixed pellets should be noted. These results indicate that there is a balance between an improvement in fuel quality and an increase in ash content. The sludge mixed pellets could be a suitable solid fuel. [ABSTRACT FROM AUTHOR]

In recent years, exploiting novel photocatalysts with a broad range of wavelengths photoresponse is undoubtedly interesting in photocatalytic field. Here, a novel Sb 2 S 3 /ultrathin g-C 3 N 4 sheets heterostructures embedded with g-C 3 N 4 quantum dots (CNS) was successfully fabricated via a facile hydrothermal process. The samples were systematically characterized by the field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), UV–vis-NIR diffuse reflection spectroscopy (UV-vis-NIR DRS) and photoluminescence (PL) spectroscopy. It is indicated that the composites have fast electron transport and enhanced solar light absorption. Moreover, the CNS composite exhibits a significant photoelectric conversion property in near-infrared (NIR) wavelength range. The photocatalytic activities of the samples were evaluated by the degradation of methyl orange (MO) upon NIR irradiation. The photodegradation rate of the optimal CNS for MO was 0.0103 min −1 , about 2.6 times higher than that of pure Sb 2 S 3 . The improved NIR photocatalytic activity may base on the improved absorption in the NIR region, efficient electron-hole separation and the up-converted PL property of g-C 3 N 4 quantum dots (CNQD). [ABSTRACT FROM AUTHOR]

The pyrolysis characteristics and kinetics of the blends produced from the mixture of torrefied camphorwood and caster bean cake (CAS) were determined by thermogravimetric analysis. Kissenger–Akahira–Sunose (KAS) and Coats–Redferm methods were applied for kinetic analysis. The results show that torrefaction can increase the maximum decomposition rate and smooth the pyrolysis reaction at 250–330 °C in the differential thermogravimetry (DTG) curves, and the additive of CAS can reduce the high maximum decomposition rate caused by torrefaction. The kinetic results suggest that the activation energy can be enhanced by torrefaction, while this can be lowered by the additive of CAS. It was found that the activation energy dropped dramatically for CAM torrefied at 300 °C by Coats–Redferm method, whereas KAS method showed the contrary trend. The pre-exponential factors by Coats–Redferm method were decreased by the processes of torrefaction and co-pelletization with CAS. In consideration of heating value and activation energy, 270 °C torrefaction and 30% CAS is conservatively selected as the optimum condition. [ABSTRACT FROM AUTHOR]

Metal-organic frameworks (MOFs) have been attracted considerable attention in the field of energy generation and environmental remediation. In this article, a novel core–shell In 2 S 3 @MIL-125(Ti) (MLS) photocatalytic adsorbent was successfully prepared by a facile solvothermal method. The as-obtained materials were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction, N 2 adsorption–desorption isotherm, X-ray photoelectron spectroscopy, UV–vis diffuse reflection spectroscopy and zeta potentials. It is indicated that the hybrids consisted of MIL-125(Ti) as the core and three-dimensional In 2 S 3 sheets network as the shell has high surface area, mesoporous structure, and improved electronegativity and visible-light absorption. The MLS exhibited excellent adsorption performance for the removal of tetracycline (TC) from water. The adsorption process is sensitive to the solution pH, ionic strength and initial TC concentration. The Langmuir isotherm and pseudo-second-order mode could well describe the adsorption process and adsorption kinetics. The adsorption mechanism is mainly responsible for surface complexation, π–π interactions, hydrogen bonding and electrostatic interactions. Further, in TC degradation experiments under visible light exposure in presence of core–shell MLS, the optimal additive content of MIL-125(Ti) in synthesis process was 0.1 g, and the corresponding photodegradation efficiency for TC was 63.3%, which was higher than that of pure In 2 S 3 and pure MIL-125(Ti). The improved photocatalytic performance was mainly ascribed to the opened porous structure, effective transfer of photo-generated carriers, Ti 3+ –Ti 4+ intervalence electron transfer and the synergistic effect between MIL-125(Ti) and In 2 S 3 . The degradation by-products of TC molecules were monitored by three-dimensional excitation-emission matrix fluorescence spectroscopy. Parts of TC molecules were mineralized into CO 2 and H 2 O. The core–shell MLS composites also revealed good performance for the removal of TC from real wastewater including medical wastewater, municipal wastewater and river water. Therefore, the novel hybrids may be used as promising photocatalytic adsorbent for wastewater purification. [ABSTRACT FROM AUTHOR]

In recent years, tremendous research efforts have been made towards developing metal-organic framework (MOF)-based composites for photocatalytic applications. In this work, bipyramid-like MIL-125(Ti) frustum enwrapped with reduced graphene oxide (rGO) and dispersed silver nanoparticles (Ag NPs) was fabricated using an efficient one-pot self-assembly and photoreduction strategy. The as-obtained materials were characterized using field emission scanning , transmission , X-ray diffraction, nitrogen adsorption-desorption isotherms, and X-ray photoelectron, ultraviolet-visible and photoluminescence spectroscopies. It is found that the as-prepared Ag/rGO/MIL-125(Ti) ternary hybrids have large surface area, microporous structure, enhanced visible light absorption and prolonged lifetime of charge carriers. Compared with pure MIL-125(Ti) and its binary counterparts, the ternary composite exhibits more efficient photocatalytic performance for Rhodamine B (RhB) degradation from water under visible light irradiation. The photodegradation rate of RhB on Ag/rGO/MIL-125(Ti) is 0.0644 min−1, which is 1.62 times higher than that of the pure MIL-125(Ti). The improved photocatalytic performance is ascribed to the indirect dye photosensitization, the Ag NP localized surface plasmon resonance, the Ti3+-Ti4+ intervalence electron transfer and the synergistic effect among MIL-125(Ti), Ag NPs and rGO. Ag NPs serve as an efficient 'electron reservoir' and rGO as an electron transporter and collector. Therefore, this work provides a new pathway into the design of MOF-based composites for application in environmental and energy fields. Copyright © 2016 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Demetalization of sewage sludge (SS) by sequential extraction before liquefaction was implemented to produce cleaner bio-char and bio-oil. Demetalization steps 1 and 2 did not cause much organic matter loss on SS, and thus the bio-oil and bio-char yields and the compositions of bio-oils were also not affected significantly. However, the demetalization procedures resulted in the production of cleaner bio-chars and bio-oils. The total concentrations and the acid soluble/exchangeable fraction (F1 fraction, the most toxic heavy metal fraction) of heavy metals (Cu, Cr, Pb, Zn, and Cd) in these products were significantly reduced and the environmental risks of these products were also relived considerably compared with those produced from raw SS, respectively. Additionally, these bio-oils had less heavy fractions. Demetalization processes with removal of F1 and F2 fractions of heavy metals would benefit the production of cleaner bio-char and bio-oil by liquefaction of heavy metal abundant biomass like SS. [ABSTRACT FROM AUTHOR]

Combustion of pelletized municipal sewage sludge (MSS) can generate pestilent byproducts: fly ash and slag. Comparisons of heavy metal sequential extraction results among MSS, fly ash and slag showed that after combustion, the bioavailable heavy metal fractions (acid soluble/exchangeable, reducible and oxidizable fractions) were mostly transformed into the very stable heavy metal fractions (residual fractions). On the other hand, the results of toxicity characteristic leaching procedure (TCLP), diethylenetriamine pentaacetic acid and HCl extraction (phyto-accessibility assessment) demonstrated that the mobility and toxicity of heavy metals were greatly reduced. The direct and long-term bioavailability and eco-toxicity of heavy metals in fly ash and slag were relieved, which implied that combustion of pelletized MSS could be a promising and completely safe disposal technology for MSS treatment. [ABSTRACT FROM AUTHOR]

Municipal sewage sludge, paper mill sludge, and slaughterhouse sludge were pyrolyzed and liquefied for the production of bio-char. The migration and transformation behavior of Cu, Cr, and Zn during pyrolysis and liquefaction of these sludges were studied. Pyrolysis and liquefaction promoted mobile fraction (F1 and F2) to stable fraction (F3 and F4). The results showed that pyrolysis and liquefaction largely affected the redistribution of Cu and Zn in raw materials. The environmental risk assessment results indicated that the environmental risk levels of Cu and Zn were significantly reduced in bio-char, and risk level of Cr was slightly decreased after pyrolysis or liquefaction. Both pyrolysis and liquefaction were promising detoxification technologies for the three sludges in terms of the mitigation of heavy metals toxicity. It was suggested that dewatered sludge could be reduced toxicity/risk before utilization by pyrolysis or liquefaction technology, especially for Cu and Zn in slaughterhouse sludge. [ABSTRACT FROM AUTHOR]