Search

Medium-low temperature pyrolysis is an effective method of retaining active components in sludge char. However, we found that incomplete cracking reactions resulted in residues of microplastics (MPs) remaining in the char; moreover, high levels of environmentally persistent free radicals (EPFRs) were detected in these MPs. Here, we investigated the temperature-dependent variations in the char-volatile products derived from sludge and MPs under different pyrolysis scenarios using multiple in situ probe coupling techniques and electron paramagnetic resonance spectroscopy, thereby identifying the sources of EPFRs and elucidating the corresponding formation-conversion mechanisms. The temperature was the key factor in the formation of EPFRs; in particular, in the 350-450 °C range, the abundance of EPFRs increased exponentially. Reactive EPFR readily formed in MPs with conjugated aromatic-ring structures (polyethylene terephthalate and polystyrene) at a temperature above 350 °C; EPFR concentrations were 5-17 times higher than those found in other types of polymers, and these radicals exhibited half-lives of more than 90 days. The EPFR formation mechanism could be summarized as solid-solid/solid-gas interfacial interactions between the polymers and the intermediate products from sludge pyrolysis (at 160-350 °C) and the homolytic cleavage-proton transfer occurring in the polymers themselves under the dual action of thermal induction and acid sites (at 350-450 °C). Based on the understanding of the evolution of EPFRs, temperature regulation and sludge components conditioning may be effective approaches to inhibit the formation of EPFRs in MPs, constituting reliable strategies to diminish the environmental risk associated with the byproducts of sludge pyrolysis.

As major components of the random matrix theory, Gaussian random matrices have been playing an important role in many fields, because they are both unitary invariant and have independent entries and can be used as models for multivariate data or multivariate phenomena. Tail bounds for eigenvalues of Gaussian random matrices are one of the hot study problems. In this paper, we present tail and expectation bounds for the ℓ 1 norm of Gaussian random matrices, respectively. Moreover, the tail and expectation bounds for the ℓ 1 norm of the Gaussian Wigner matrix are calculated based on the resulting bounds. Compared with existing results, our results are more suitable for the high-dimensional matrix case. Finally, we study the tail bounds for the parameter vector of some existing regularization algorithms.

Point-of-use (POU) devices with satisfying mercury (Hg) removal performance are urgently needed for public health and yet are scarcely reported. In this study, a thiol-laced metal-organic framework (MOF)-based sponge monolith (TLMSM) has been investigated for Hg(II) removal as the POU device for its benchmark application. The resulting TLMSM was characterized by remarkable chemical resistance, mechanical stability, and hydroscopicity (2100 wt %). Importantly, the TLMSM has exhibited high adsorption capacity (∼954.7 mg g

Despite of the extensive research in semiconductor photocatalysis with respect to material and device innovations, much of the fundamental aquatic chemistry of those new materials that governs their environmental hazard and implications remains poorly understood. BiVO

Purposively designing environmental advanced materials and elucidating the underlying reactivity mechanism at the atomic level allows for the further optimization of the removal performance for contaminants. Herein, using well facet-controlled I-Cu2WS4 single crystals as a model transition metal chalcogenide sorbent, we investigated the adsorption performance of the exposed facets toward gaseous elemental mercury (Hg0). We discovered that the decahedron exhibited not only facet-dependent adsorption properties for Hg0 but also recrystallization along the preferential [001] growth direction from a metastable state to the steady state. Besides, the metastable crystals with a predominant exposure of {101} facets dominated the promising adsorption efficiency (about 99% at 75 °C) while the saturated adsorption capacity was evaluated to be 2.35 mg·g-1. Subsequently, comprehensive characterizations and X-ray adsorption fine structure (XAFS), accompanied by density functional theory (DFT) calculations, revealed that it might be owing to the coordinatively unsaturated local environment of W atoms with S defects and the surface relative stability of different facets, which could be affected by the change in surface atom configuration. Hence, the new insight into the facet-dependent adsorption property of transition metal chalcogenide for Hg0 may have important implications, and the atomic-level study directly provides instructions for development and design of highly efficient functional materials.

Adsorption is widely applied in both potable and municipal or industrial wastewater treatments process. Nanomaterial adsorbents (NAs) have emerged as efficient candidates to remove toxic metals fro...

Mercury (Hg) removal is crucial to the safety of water resources, yet it lacks an effective removal technology, especially for emergency on-site remediation. Herein, multilayered oxygen-functionali...

Conversion of sewage sludge to biochar for contaminants removal from water achieves the dual purpose of solid waste reuse and pollution elimination, in line with the concept of circular economy and carbon neutrality. However, the current understanding of sludge-derived biochar (SDB) for wastewater treatment is still limited, with a lack of summary regarding the effect of modification on the mechanism of SDB adsorption/catalytic removal aqueous contaminants. To advance knowledge in this aspect, this paper systematically reviews the recent studies on the use of (modified) SDB as adsorbents and in persulfate-based advanced oxidation processes (PS-AOPs) as catalysts for the contaminants removal from water over the past five years. Unmodified SDB not only exhibits stronger cation exchange and surface precipitation for heavy metals due to its nitrogen/mineral-rich properties, but also can provide abundant catalytic active sites for PS. An emphatic summary of how certain adsorption removal mechanisms of SDB or its catalytic performance in PS-AOPs can be enhanced by targeted regulation/modification such as increasing the specific surface area, functional groups, graphitization degree, N-doping or transition metal loading is presented. The interference of inorganic ions/natural organic matter is one of the unavoidable challenges that SDB is used for adsorption/catalytic removal of contaminants in real wastewater. Finally, this paper presents the future perspectives of SDB in the field of wastewater treatment. This review can contribute forefront knowledge and new ideas for advancing sludge treatment toward sustainable green circular economy.

Waste activated sludge (WAS) has low biodegradability that restricts acidogenic fermentation (AF), thereby limiting the high-value volatile fatty acids (VFAs) production. This study investigated an alternative electrochemical pretreatment (EPT) approach that can facilitate AF of WAS and food waste (FW) and therefore enhance VFAs production. The results showed through introducing 50 % volatile solid basis of FW (containing massive chloride) into WAS, a 60-min EPT produced reactive chlorine species (RCS), which diffused into WAS-FW inner layers resulting in cell lysis, therefore significantly promoted and accelerated WAS-FW disintegration, contributing to more soluble and biodegradable dissolved organic matter (DOM). Then during the subsequent 15-day acidogenic co-fermentation (Co-AF), the residual RCS (approximate 5 mg Cl

Valorizing solid waste for heavy metal adsorption is highly desirable to avoid global natural resources depletion. In this study, we developed a new protocol to valorize Radix Astragali residue (one of the Chinese medicine residues) into a low-cost, chemically robust, and highly permeable (ca. 90%) amino-laced porous double-network hydrogel (NH

The transfer and fate of methylmercury (MeHg) in typical components, such as sediment, sediment-inhabiting animals, pelagic fish, and three large waterfowls, namely, red-crowned crane (Grus japonensis), mallard (Anas platyrhynchos), and oriental stork (Ciconia boyciana), of the ecosystem in China’s Zhalong Wetland were examined using equivalence-based mass balance model. The biomagnification degree of MeHg increased on the species at the high trophic level of the system. Hence, elevated MeHg concentration (3.2 μg g−1, dry weight) was detected in the endangered G. japonensis. The accumulation of the organometal generally followed the decreasing order of oriental stork (carnivore) > mallard (omnivore) > red-crowned crane (omnivore). The predicted results of MeHg at each node of the food web were generally in accordance with the measured values (F = 0.09, P = 0.78), implying that the model is suitable for the prediction of MeHg fate in the inland aquatic system. According to the model, the respiration for the species at low trophic strata was the key input source of MeHg, but ingestion played an important role for MeHg intake in the species at the high trophic position in the food web. Metabolism was a crucial pathway of MeHg loss for the top predators in the ecosystem.

Reducing energy use is crucial to commercialize electrochemical oxidation technologies. We developed a three-dimensional (3-D) electrochemical system that can significantly reduce the applied voltage and effectively degrade organic contaminants in low-ionic-strength wastewaters. The 3-D system consisted of a composite wire mesh anode (composed of blue TiO2 nanotubes covered with SnO2-Sb2O3), a proton exchange membrane, and a stainless-steel wire mesh cathode, which were compressed firmly together. For the 3-D system, we placed the anode of a 3-D electrode toward the wastewater that flowed past the anode. Both the two-dimensional (2-D) and 3-D systems had the same anode and cathode. We found that the 3-D system could reduce the applied voltage by 75.7% and reduce the electrical efficiency per log order reduction (EE/O) by 73% for 0.001 M Na2SO4. For Na2SO4 concentrations greater than 0.05 M, the 2-D system had a slightly lower EE/O. We also compared the EE/O of electrochemical advanced oxidation processes (EAOPs) with that of other advanced oxidation processes (UV/H2O2, UV/persulfate, O3/H2O2, UV/ TiO2, and UV/chlorine). We found that EAOPs have a much higher EE/O for low BA concentrations (20 mg/L) and a much lower EE/O for high BA concentrations (2000 mg/L).

An understanding of the impacts regarding different phases of inorganic materials on heavy metal removal is indispensable, owing to the intrinsic structure of materials that can affect its properties. In this study, the distinct adsorption behaviors of heavy metals (Pb(II) and Cu(II)) on different phases of MoS2 (metallic phase (1T) and semiconducting phase (2H)) were theoretically and experimentally investigated. According to the computational results, both Pb(II) and Cu(II) have formed more stable complexes on 1T-MoS2 compared to those on 2H-MoS2 due to the lower adsorption energy (Ead). This phenomenon indicates that Pb(II) and Cu(II) were more preferably adsorbed onto 1T-MoS2. Based on the results of the computational studies, two-dimensional (2D) MoS2 nanosheets with identical 1T and 2H phases were synthesized via a facile hydrothermal reaction. As we surmised, 1T-MoS2 achieved excellent Pb(II) and Cu(II) adsorption capacities, which were 147.09 and 82.13 mg/g at 298 K, respectively, compared to those of 2H-MoS2 (i.e., 64.16 and 50.74 mg/g at 298 K). Moreover, 1T-MoS2 has shown other superior properties, such as (i) ultrafast adsorption kinetics and (ii) great anti-interference activity toward other existing cations, compared to 2H-MoS2. Extensive computations and characterizations of MoS2-Pb and -Cu adsorption complexes illustrated that the active S sites were indispensable for heavy metal adsorption. Overall, for the first time, we provide evidence that 1T-MoS2 is more functional in heavy metal removal compared to 2H-MoS2, which can guide and expand the applications of MoS2-based adsorbents in environmental remediation.

Benzophenone derivatives, including benzophenone-1 (C13H10O3, BP1), benzophenone-3 (C14H12O3, BP3) and benzophenone-8 (C14H12O4, BP8), that used as UV filters are currently viewed as emerging contaminants. Degradation behaviors on co-exposure benzophenone derivatives using UV-driven advanced oxidation processes under different aqueous environments are still unknown. In this study, the degradation behavior of mixed benzophenone derivatives via UV/H2O2 and UV/peroxydisulfate (PDS), in different water matrices (surface water, hydrolyzed urine and seawater) were systematically examined. In surface water, the attack of BP3 by hydroxyl radicals (HO∙) or carbonate radicals (CO3∙-) in UV/H2O2 can generate BP8, which was responsible for the relatively high degradation rate of BP3. Intermediates from BP3 and BP8 in UV/PDS were susceptible to CO3∙-, bringing inhibition of BP1 degradation. In hydrolyzed urine, Cl− was shown the negligible effect for benzophenone derivatives degradation due to low concentration of reactive chlorine species (RCS). Meanwhile, BP3 abatement was excessively inhibited during co-exposure pattern. In seawater, non-first-order kinetic behavior for BP3 and BP8 was found during UV/PDS treatment. Based on modeling, Br− was the sink for HO∙, and the co-existence of Br− and Cl− was the sink for SO4∙-. The cost-effective treatment toward target compounds removal in different water matrices was further evaluated using EE/O. In most cases, UV/H2O2 process is more economically competitive than UV/PDS process.

Solar energy is a renewable resource that can supply our energy needs in the long term. A semiconductor photocatalysis that is capable of utilizing solar energy has appealed to considerable interests for recent decades, owing to the ability to aim at environmental problems and produce renewal energy. Much effort has been put into the synthesis of a highly efficient semiconductor photocatalyst to promote its real application potential. Hence, we reviewed the most advanced methods and strategies in terms of (i) broadening the light absorption wavelengths, (ii) design of active reaction sites, and (iii) control of the electron-hole (e--h+) recombination, while these three processes could be influenced by remodeling the crystal lattice, surface, and interface. Additionally, we individually examined their current applications in energy conversion (i.e., hydrogen evolution, CO2 reduction, nitrogen fixation, and oriented synthesis) and environmental remediation (i.e., air purification and wastewater treatment). Overall, in this review, we particularly focused on advanced photocatalytic activity with simultaneous wastewater decontamination and energy conversion and further enriched the mechanism by proposing the electron flow and substance conversion. Finally, this review offers the prospects of semiconductor photocatalysts in the following three vital (distinct) aspects: (i) the large-scale preparation of highly efficient photocatalysts, (ii) the development of sustainable photocatalysis systems, and (iii) the optimization of the photocatalytic process for practical application.

A broad bandgap and detrimental recombination of photoexcited h+-e− pairs are fatal deficiencies for using the g-C3N4 visible light water splitting. Herein, a sea-urchin-structure g-C3N4 (CNSC) with ∼2.0 eV bandgap was prepared using a hydrothermal strategy. It is important to note that CNSC can efficiently suppress h+-e− pair recombination and has a narrow bandgap which can utilize more visible light. Conventional g-C3N4 has a ∼2.7 eV bandgap and valence band (VB) potential of +1.83 V vs. NHE but the VB of CNSC is +1.55 V. As a result, CNSC does not create H2O2, which can passivate g-C3N4. Density functional theory (DFT) confirms that C N, C O, and OH groups in the CNSC shift the d-band centre of Pt closer to Fermi level, leading to better stabilization of adsorbate and higher catalytic performance. Photo-depositing Pt on the CNSC, 3 wt% Pt/CNSC produces H2 and O2 evolution rate (HER and OER) of 41.5 and 20.3 μmol g-1 h-1 (apparent quantum efficiency: 0.43% at 420 ± 10 nm), respectively, 30 times greater than HER of 2 wt% Pt/bulk g-C3N4 in overall water splitting under visible-light (λ ≥ 420 nm). This work provides an innovative approach to construct hierarchical nanostructure g-C3N4 with narrow bandgap and paves the pathway for development of water splitting photocatalysts.

Increasing numbers of cement furnaces have applied selective catalytic reduction (SCR) units for advanced treatment of NO in the flue gas. However, the SCR catalysts may face various poisons, such as acidic, alkaline, and heavy metal species, in the fly ash. In this work, we studied the deactivation mechanisms of multipoisons (Ca, Pb, and S) on the CeO

Recently, the UV/free chlorine process has gained attention as a promising technology for destroying refractory organic contaminants in the aqueous phase. We have developed a kinetic model based on first-principles to describe the kinetics and mechanisms of the oxidation of organic contaminants in the UV/free chlorine process. Substituted benzoic acid compounds (SBACs) were chosen as the target parent contaminants. We determined the second-order rate constants between SBACs and reactive chlorine species (RCS; including [Formula: see text], [Formula: see text] and [Formula: see text]) by fitting our model to the experimental results. We then predicted the concentration profiles of SBACs under various operational conditions. We analyzed the kinetic data and predicted concentration profiles of reactive radicals ([Formula: see text] and RCS), we found that [Formula: see text] was the dominant radicals for SBACs destruction. In addition, we established quantitative structure activity relationships (QSARs) that can help predict the second-order rate constants for SBACs destruction by each type of reactive radicals using SBACs Hammett constants. Our first-principles-based kinetic model has been verified using experimental data. Our model can facilitate a design for the most cost-effective application of the UV/free chlorine process. For example, our model can determine the optimum chlorine dosage and UV light intensity that result in the lowest energy consumption.

A novel electrocatalytic system was developed to realize one-pot conversion of organic pollutants into liquid fuels such as methanol (CH3OH) and ethanol (C2H5OH). The process combines the catalytic oxidation of organic pollutants with electrocatalytic reduction of CO2. We first coupled the electrocatalytic process with SO4•−-based advanced oxidation processes (AOPs) for the degradation of 4-nitrophenol (4-NP) using a 3D-hexagonal Co3O4 anode. In this step, 4-NP was mineralized to CO2, and then the CO2 was converted to CH3OH and C2H5OH by electrocatalytic reduction using a flower-like CuO cathode. The experimental results show the destruction of 4-NP (60 mL, 10 mg/L) can be as high as 99%. In addition, the yields of CH3OH and C2H5OH were 98.29 μmol/L and 40.95 μmol/L, respectively, which represents a conversion of 41.8% of 4-NP into liquid fuels; the electron efficiency was 73.1%. In addition, we found that 3D-hexagonal arrays of Co3O4 with different morphologies can be obtained by adding different amounts of urea. We also investigated the formation mechanism of novel 3D-hexagonal Co3O4 arrays for the first time. A mechanism was proposed to explain the electrocatalytic steps involved in the conversion of 4-NP to CH3OH and C2H5OH and the synergetic effects between AOPs and electrocatalysis.

The increasing anthropogenic inputs of Pb and Cd into China’s Nen River (Qiqihar section) owing to rapid urbanization in the past 50 years may pose ecological risks to the river’s aquatic system. To confirm this hypothesis, we determined the Pb and Cd concentrations in the sediments of the Nen River flowing across Qiqihar City by comparing the control group (samplings in the Nen River branch bypassing the city) and bioaccumulation along the food chain. We found significantly higher Pb concentrations in the sediments than in the control group (39.21 mg kg−1 dry weight [dw] vs. 22.44 mg kg−1 dw; p

Prussian blue analogues (PBA) are efficient catalysts for peroxymonosulfate (PMS) activation. However, the longevity and recovery ability of PBA are very poor, which limits their practical applications. In this study, for the first time, we successfully incorporated a nanosheet-like PBA into the interlayers of layered double hydroxides (LDH) (PBA-LDH). The morphology and physicochemical characteristics of the as-synthesized PBA-LDH were well characterized using SEM, TEM, XRD, FTIR and XPS. PMS activation via PBA-LDH toward carbamazepine (CBZ) degradation was systematically examined. The activation of PMS via PBA alone could only achieve a maximum of 31.8% degradation efficiency for CBZ within 15 min. However, complete degradation of CBZ was achieved via a PBA-LDH-activated PMS system within a wide pH range of 3.0 to 9.0. ESR measurements and radical scavenging experimental results revealed that SO4˙− is the most active species in CBZ degradation. XPS analysis confirmed a reversible valence equilibrium between the metal ions and the recovery of surface-adsorbed oxygen, ensuring stable catalytic activity. Notably, the CBZ degradation in the PBA-LDH activated system remained as high as 95.7% after six consecutive runs. Meanwhile, only 8.1 μg L−1 cobalt ion and 5.4 μg L−1 iron ion were leached from PBA-LDH after the degradation reaction; thus, it is non-toxic to aqueous environments. In addition, a possible pathway for CBZ degradation was proposed, and an eco-toxicity assessment of the oxidation intermediates was also performed.

The complexity of sludge components and the heterogeneity of pyrolysis products make it challenging to trace char-volatile evolutions and interaction mechanisms during pyrolysis. Herein, we systematically dissected the solid-state reactions and volatile dynamic variations via in-situ infrared/mass spectral probes coupled signal amplification techniques. The identification of hidden reactions was further enhanced by comparing the discrepancies in the pyrolysis of three systems: raw sludge, sludge-extracted organics, and pseudo-components of organics. A three-stage sludge pyrolysis of bond cleavage (α = 0.2-0.5), intermediates diffusion (α = 0.5-0.7), and interface interaction (α = 0.7-0.8) was proposed through solid-state reaction tracing, and the pyrolysis reaction was found to be dominated by the first two stages. The generation of reactive intermediates accelerated the collision frequency between reactants, which increased the order of solid-state reactions and raised the energy barrier from 148 to 180-261-297 kJ/mol. The temperature-response sequence of the major pyrolysis volatiles was H

Oxcarbazepine (OXC) is ubiquitous in the aqueous environment. And due to its ecotoxicological effects and potential risks to human, an effective way to eliminate OXC from aqueous environment has aroused public concerns in recent years. Radical-based reactions have been shown to be an efficient way for OXC destruction, but the reactions of OXC with reactive oxygen species (ROS) and carbonate radical (CO3•−) are still unclear. In this study, we focused the degradation of OXC and ROS, CO3•− generation mechanism, and their roles in OXC degradation via UV and UV/H2O2. The triplet state of oxcarbazepine (3OXC∗) was found to play an important role in OXC degradation via UV. And hydroxyl radicals (•OH) and singlet oxygen (1O2) were found to be the dominant ROS in OXC degradation. Superoxide radical (O2•−) did not react with OXC directly, but it may react with intermediate byproducts. Generation of CO3•− played a positive role on OXC degradation for both UV and UV/H2O2. In addition to •OH, 3OXC* also contribute to CO3•− production. The second-order rate constants of OXC with •OH and CO3•− were 1.7 × 1010 M−1 s−1 and 8.6 × 107 M−1 s−1, respectively. Potential OXC degradation mechanisms by •OH were proposed and included hydroxylation, α-ketol rearrangement, and benzylic acid rearrangement. Compared with non-selective •OH, the reactions involving CO3•− are mainly electron transfer and hydrogen abstraction. And the acute toxicity of OXC was lower after UV/H2O2 and UV/H2O2/HCO3− treatments, which was confirmed by luminescent bacterial assay (Vibrio fischeri bacterium).

Background: Refeeding syndrome (RFS) is a group of metabolic disorders associated with refeeding after starvation. However, the diagnostic criteria of RFS are highly heterogeneous. This study aimed to identify the best diagnostic criteria of RFS in critically ill patients.Methods: A multicenter, parallel, prospective trial enrolled patients (≥18 years) with mechanical ventilation for more than 3 days. RFS, defined as new-onset hypophosphatemia (Results: Between May 1, 2019 and April 30, 2020, 312 patients were enrolled. Of these, 302 patients were included and completed the trial. Except for APACHE II, there were no significant differences in age, gender, admission type, diagnosis, furosemide application, and hormone application. In the RFS2 and RFS3 groups, the APACHE II score was significantly higher than the non-RFS group (p=0.009 and p=0.01, respectively). In the nutritional baseline data, there were no significant differences between the groups in the PNI index, time to start of nutrition treatment, percentage of start nutrition within 48 hours, parenteral nutrition, feeding intolerance, and caloric intake and protein intake within first week. The NRS2002 score in group 2 and 3 was higher than the non-RFS group (pConclusions: The optimal criterion of RFS was a decrease in serum phosphate level of 0.65mmol/L and below, and a reduction of greater than 0.16 mmol/L within 72 h after starting nutritional support. Trial registration: ClinicalTrials.gov database, NCT04005300. Registered 1 July 2019, https://clinicaltrials.gov/ct2/show/ NCT04005300

Based on the local T-S model, the switching control method for the nonlinear response of the seismic surface is studied, and the stiffness matrix of the composite interlayer element of viscoelastic damper and herringbone support is derived. The high-order single step 6 method is applied to the nonlinear seismic response analysis and the instantaneous optimal active switching control. The local T-S model and controller are designed, and the approach and control of global nonlinear responses are realized through the multi-model switching control. The results show that the proposed method can accurately reflect the reduction of seismic ground load and the switching control of the main structure when the viscoelastic damper is installed. The switching control effect of the maximum spatial displacement becomes more and more obvious with the change of time history, and the control effect of all layers applying the switching control force is the most significant. Whether the controller is disturbed or not, it is always good and stable performance. RESUMEN Este artículo estudia el método de control de conmutación para la respuesta no lineal de la superficie sísmica con base en el modelo local T-S, y deriva la matriz de rigidez del elemento compuesto de capa intermedia del amortiguador viscoelástico y el soporte de espiga. El método 6 de un solo paso de alto orden se aplica al análisis de respuesta sísmica no lineal y al control de conmutación activo óptimo instantáneo. El modelo local T-S y el controlador están diseñados, y el enfoque y el control de la respuesta global no lineal se realizan a través del control de conmutación multimodelo. Los resultados muestran que el método propuesto puede reflejar con precisión la reducción de la carga de tierra sísmica y el control de conmutación de la estructura principal cuando se instala el amortiguador viscoelástico. El efecto de control de cambio del desplazamiento espacial máximo se vuelve cada vez más obvio con el cambio del historial de tiempo, y el efecto de control de todas las capas que aplican la fuerza de control de cambio es el más significativo. Ya sea que el controlador esté alterado o no, siempre es un rendimiento bueno y estable.