Tunable schiff-based networks with different bonding sites for enhanced photocatalytic activity under visible-light irradiation: The effects of steric hindrance.

Organic polymers hold great potential in photocatalysis considering their low cost, structural tailorability, and well-controlled degree of conjugation for efficient electron transfer. Among the polymers, Schiff base networks (SNWs) with high nitrogen content have been noticed. Herein, a series of SNWs is synthesized based on the melamine units and dialdehydes with different bonding sites. The chemical and structural variation caused by steric hindrance as well as the related photoelectric properties of the SNW samples are investigated, along with the application exploration on photocatalytic degradation and energy production. The results demonstrate that only SNW-o based on o-phthalaldehyde responds to visible light, which extends to over 550 nm. SNW-o shows the highest tetracycline degradation rate of 0.02516 min-1, under 60-min visible light irradiation. Moreover, the H2O2 production of SNW-o is 2.14 times higher than that of g-C3N4. The enhanced photocatalytic activity could be ascribed to the enlarged visible light adsorption and intramolecular electron transfer. This study indicates the possibility to regulate the optical and electrical properties of organic photocatalysts on a molecular level, providing an effective strategy for rational supramolecular engineering to the applications of organic materials in photocatalysis.

Insight into the selection of oxidant in persulfate activation system: The effect of the target pollutant properties.

As a rising branch of advanced oxidation processes, persulfate activation has attracted growing attention. Unlike catalysts that have been widely studied, the selection of persulfate is previously overlooked. In this study, the affecting factors of persulfates were studied. The effect of target pollutant properties on superior persulfate species (the species with a higher degradation efficiency) was investigated by multiwalled carbon nanotube (MWCNT)/persulfate catalytic systems. Innovatively, the EHOMO (or vertical ionization potential (VIP)) value of the target pollutant was proposed to be an index to judge the superior persulfate species, and the threshold is VIP= 6.397-6.674 eV, EHOMO= -8.035∼- 7.810 eV, respectively. To be specific, when the VIP of phenolic compounds is higher (or EHOMO of phenolic compounds is lower) than the threshold, the catalytic performance of peroxymonosulfate would be higher than that of peroxydisulfate. Moreover, the effects of coexisting cations on peroxydisulfate superior species were further investigated. It was illustrated that the hydrated cation radius of coexisting cations would influence the pollutant degradation efficiency under some circumstances. This study provides a new approach to improve the cost of persulfate activation systems and promotes the underlying downstream application of persulfate activation systems.

Tuning the intrinsic catalytic sites of magnetite to concurrently enhance the reduction of H2O2 and O2: Mechanism analysis and application potential evaluation.

Heterogeneous Fenton-like process based on H2O2 activation has been widely tested for water purification, but its application still faces some challenges such as the use of high doses of chemicals (including catalysts and H2O2). Herein, a facile co-precipitation method was utilized for small-scale production (∼50 g) of oxygen vacancies (OVs)-containing Fe3O4 (Vo-Fe3O4) for H2O2 activation. Experimental and theoretical results collaboratively verified that H2O2 adsorbed on the Fe site of Fe3O4 tended to lose electrons and generate O2•-. While the localized electron from OVs of Vo-Fe3O4 could assist in donating electrons to H2O2 adsorbed on OVs sites, this allowed more H2O2 to be activated to •OH, which was 3.5 folds higher than Fe3O4/H2O2 system. Moreover, the OVs sites promoted dissolved oxygen activation and decreased the quenching of O2•- by Fe(III), thus promoting the generation of 1O2. Consequently, the fabricated Vo-Fe3O4 achieved much higher oxytetracycline (OTC) degradation rate (91.6%) than Fe3O4 (35.4%) at a low catalyst (50 mg/L) and H2O2 dosage (2 mmol/L). Importantly, further integration of Vo-Fe3O4 into fixed-bed Fenton-like reactor could effectively eliminate OTC (>80%) and chemical oxygen demand (COD) (21.3%∼50%) within the running period. This study provides promising strategies for enhancing the H2O2 utilization of Fe mineral.

Catalyst-Free Photochemical Activation of Peroxymonosulfate in Xanthene-Rich Systems for Fenton-Like Synergistic Decontamination: Efficacy of Proton Transfer Process.

Catalyst-free visible light assisted Fenton-like catalysis offers opportunities to achieve the sustainable water decontamination, but the synergistic decontamination mechanisms are still unclear, especially the effect of proton transfer process (PTP). The conversion of peroxymonosulfate (PMS) in photosensitive dye-enriched system was detailed. The photo-electron transfer between excited dye and PMS triggered the efficient activation of PMS and enhanced the production of reactive species. Photochemistry behavior analysis and DFT calculations revealed that PTP was the crucial factor to determine the decontamination performance, leading to the transformation of dye molecules. The excitation process inducing activation of whole system was composed of low energy excitations, and the electrons and holes were almost contributed by LUMO and HOMO. This work provided new ideas for the design of catalyst-free sustainable system for efficient decontamination.

Insight into the effect of pyrolysis temperature on photoreactivity of biochar-derived dissolved organic matter: Impacts of aromaticity and carbonyl groups.

Practical application of biochar may result in more biochar-derived dissolved organic matter (denoted as BDOM) inevitably release into surface waters by infiltration and surface runoff. The photochemical reaction of BDOM has gained intense attention, which played a key role in the fate of organic contaminants. However, the relationships between specific characteristics of BDOM and its photoreactivity are still uncertain. In this study, the characteristics of BDOM pyrolyzed from rice husk derived biochar at different temperature (from 400 °C to 700 °C) and their effect on the photodegradation of oxytetracycline (OTC) were carefully investigated. The 13C NMR and EEM results indicated the dominated component of BDOM was gradually turned from humic acid like substances with low aromaticity to high aromaticity with abundant oxygen-containing functional groups as pyrolytic temperature increases. Experimental results showed that the apparent rate constants (kobs) of BDOM700 (4.53 × 10-2 min-1) for OTC photodegradation was approximately one order of magnitude higher than BDOM400 (4.52 × 10-3 min-1), which was closely correlated with their aromaticity (R2 = 0.944). It was found that 3BDOM* rather than 1O2 played the major role in BDOM mediated photodegradation of OTC (80.13 % vs 14.34 %), and the carbonyl-containing group was identified as the main 3BDOM* precursor by NaBH4 reduction experiment. This work highlighted both aromaticity and carbonyl group contents were critical indicators for assessing the potential to generate 3BDOM* and corresponding photoreactivity.

Fault Detection and Classification of CIGS Thin-Film PV Modules Using an Adaptive Neuro-Fuzzy Inference Scheme.

The use of artificial intelligence to automate PV module fault detection, diagnosis, and classification processes has gained interest for PV solar plants maintenance planning and reduction in expensive inspection and shutdown periods. The present article reports on the development of an adaptive neuro-fuzzy inference system (ANFIS) for PV fault classification based on statistical and mathematical features extracted from outdoor infrared thermography (IRT) and I-V measurements of thin-film PV modules. The selection of the membership function is shown to be essential to obtain a high classifier performance. Principal components analysis (PCA) is used to reduce the dimensions to speed up the classification process. For each type of fault, effective features that are highly correlated to the PV module's operating power ratio are identified. Evaluation of the proposed methodology, based on datasets gathered from a typical PV plant, reveals that features extraction methods based on mathematical parameters and I-V measurements provide a 100% classification accuracy. On the other hand, features extraction based on statistical factors provides 83.33% accuracy. A novel technique is proposed for developing a correlation matrix between the PV operating power ratio and the effective features extracted online from infrared thermal images. This eliminates the need for offline I-V measurements to estimate the operating power ratio of PV modules.

Spatial confinement: A green pathway to promote the oxidation processes for organic pollutants removal from water.

Organic pollutants removal from water is pressing owing to the great demand for clean water. Oxidation processes (OPs) are the commonly used method. However, the efficiency of most OPs is limited owing to the poor mass transfer process. Spatial confinement is a burgeoning way to solve this limitation by use of nanoreactor. Spatial confinement in OPs would (i) alter the transport characteristics of protons and charges; (ii) bring about molecular orientation and rearrangement; (iii) cause the dynamic redistribution of active sites in catalyst and reduce the entropic barrier that is high in unconfined space. So far, spatial confinement has been utilized for various OPs, such as Fenton, persulfate, and photocatalytic oxidation. A comprehensive summary and discussion on the fundamental mechanisms of spatial confinement mediated OPs is needed. Herein, the application, performance and mechanisms of spatial confinement mediated OPs are overviewed firstly. Subsequently, the features of spatial confinement and their effects on OPs are discussed in detail. Furthermore, environmental influences (including environmental pH, organic matter and inorganic ions) are studied with analyzing their intrinsic connection with the features of spatial confinement in OPs. Lastly, challenges and future development direction of spatial confinement mediated OPs are proposed.

Unveiling the roles of dissolved organic matters derived from different biochar in biochar/persulfate system: Mechanism and toxicity.

Biochar has been frequently used as a persulfate (PS) activator due to its attractive properties, but dissolved organic matter (DOM) derived from the non­carbonized part of biochar has received less attention, not to mention its specific role and impact in biochar/PS systems. In this study, wheat straw, municipal sludge, and swine bone were selected as the representative feed stocks of biochar. Subsequently, these three types of biochar were adopted to explore the roles of DOM in biochar/PS systems. Although the composition and amount of DOM derived from different biochar were discrepant, they exhibited similar effect in biochar/PS systems. To be specific, the pore-clogging effect of DOM on biochar suppressed the adsorption capacity and catalytic performance of the three biochar. Furthermore, the removal of DOM decreased the environmental risk of these biochar/PS systems and enhanced the stability of the involved biochar. With respect to the variation in degradation mechanism, the removal of DOM increased the proportion of electron transfer pathway in unison, but the diminution in the roles of O2•¯ and 1O2 was more remarkable in bone-derived-biochar/PS systems. Additionally, the toxicity test illustrated that the leakage and accumulation of DOM were toxic to Chlorella sp., and the DOM from sludge-derived-biochar presented the highest toxicity. Overall, this study analyzes the roles of DOM derived from different biochar in biochar/PS systems and evaluates their environmental risk, which contributes to a comprehensive understanding of the fate of DOM derived from biochar.

Single atom Mn anchored on N-doped porous carbon derived from spirulina for catalyzed peroxymonosulfate to degradation of emerging organic pollutants.

Highly efficient single atom catalysts are critical to substantially promote for peroxymonosulfate (PMS) activation to organic pollutant degradation, but it remains a challenge at present. Herein, single atom Mn anchored on N-doped porous carbon (SA-Mn-NSC) was synthesized by ball milling of Mn-doped carbon nitride and spirulina biochar to dominantly activate PMS. The precursor of carbon nitride and spirulina possessed a strong coordinating capability for Mn(II), facilitating the formation of highly dispersed nitrogen-coordinated Mn sites (Mn-N4). The SA-Mn-NSC catalyst exhibited high activity and stability in the heterogeneous activation of PMS to degrade a wide range of pollutants within 10 min, showing an outstanding degradation rate constant of 0.31 min-1 in enrofloxacin (ENR) degradation. The high surface density of Mn-N4 sites and abundant interconnected meso-macro pores were highly favorable for activating PMS to produce 1O2 and high-valent manganese (Mn(IV)) for pollutant degradation. This work offers a new pathway of using a low-cost and easily accessible single-atom catalysts (SACs) and could inspire more catalytic oxidation strategies.

Processable Conjugated Microporous Polymer Gels and Monoliths: Fundamentals and Versatile Applications.

Conjugated microporous polymers (CMPs) as a new type of conjugated polymers have attracted extensive attention in academia and industry because of the combination of microporous structure and π-electron conjugated structure. The construction and application of gels and monoliths based on CMPs constitute a fertile area of research, promising to provide solutions to complex environmental and energy issues. This review summarizes and objectively analyzes the latest advances in the construction and application of processable CMP gels and monoliths, linking the basic and enhanced properties to widespread applications. In this review, we open with a summary of the construction methods used to build CMP gels and monoliths and assess the feasibility of different preparation techniques and the advantages of the products. The CMP gels and monoliths with enhanced properties involving various special applications are then deliberated by highlighting relevant scientific literature and discussions. Finally, we present the issues and future of openness in the field, as well as come up with the major challenges hindering further development, to guide researchers in this field.

Alfalfa biochar supported Mg-Fe layered double hydroxide as filter media to remove trace metal(loid)s from stormwater.

Polluted stormwater (PSW) treatment is becoming increasingly important because of the existence of multiple pollutants from non-point pollution sources. Alfalfa biochar loaded with Mg/Fe layered double hydroxide (AF-LDH) was successfully synthesized to remove trace metal(loid)s from stormwater. The adsorption kinetics and isotherms of metal(loid)s in a mono-component system and the reusability of the composite materials was investigated in this study. The result showed that the maximum removal efficiency for Pb(II), Cu(II), Zn(II), Cd(II), As(V), and Cr(VI) were 98.98 %, 98.11 %, 97.88 %, 97.71 %, 98.81 %, and 50.89 %, respectively, when added calcined AF-LDH (AF-LDO) composite material to the multi-component solution. The AF-LDH and AF-LDO could efficiently remove trace pollutants (10-100 µg/L) from multi-component solution, especially for AF-LDO, which could completely remove the tested six trace metal(loid)s. Furthermore, Fourier transform infrared spectra and X-ray diffraction characterizations supported the Mg/Fe layered double hydroxide reconstruction. The main mechanisms of Pb(II), Cu(II), Zn(II), and Cd(II) (cationic metals) removal were ion exchange and surface precipitation, whereas As(V) and Cr(VI) (anionic metals) were mainly dislodged through the formation of surface complexation, electrostatic attraction, and interlayer anion exchange, concerning the -OH and -COOH of AF-LDH. Importantly, the results of the column experiment demonstrated that AF-LDO was superior to AF-LDH for anionic metal removal from stormwater. In this study, we synthesized AF-LDH and AF-LDO for trace metal(loid) removal and proposed a new and practical approach for stormwater purification.

Microplastics in landfill and leachate: Occurrence, environmental behavior and removal strategies.

Plastic wastes buried in landfill are gradually broken and decomposed into microplastics under physical, chemical and biological effects, bringing environmental risks to the exploitation of waste resources. Landfill leachate as a potential source of environmental microplastics has not good attention. Microplastics in leachate carry toxic and harmful pollutants and antibiotic resistance genes, and these vectors pose greater risks to human and environmental health without systematic treatment. Recently, the main technologies of landfill leachate treatment process include order batch activated sludge process, membrane biological reaction process, flocculation process, combined filtration process, and constructed wetland process. However, there is still little knowledge about microplastic removal of the existing leachate treatment facilities, and some technologies to alleviate the sources of such microplastics should be timely developed. This paper systematically summarizes the occurrence of plastics, microplastics and nanoplastics in leachate and their interactive pollution with other toxic pollutants. Meanwhile, the prospects of their environmental behaviors in landfill and leachate are put forward. The microplastic removal by existing leachate treatment equipment and the limitations and challenges to upgrading process of development and implementation are also discussed. The paper can provide a scientific basis for studying the fate of microplastics in landfill and leachate.

Modeling and simulation of high energy density lithium-ion battery for multiple fault detection.

Lithium-ion battery, a high energy density storage device has extensive applications in electrical and electronic gadgets, computers, hybrid electric vehicles, and electric vehicles. This paper presents multiple fault detection of lithium-ion battery using two non-linear Kalman filters. A discrete non-linear mathematical model of lithium ion battery has been developed and Unscented Kalman filter (UKF) is employed to estimate the model parameter. Occurrences of multiple faults such as over-charge, over-discharge and short circuit faults between inter cell power batteries, affects the parameter variation of system model. Parallel combinations of some UKF (bank of filters) compare the model parameter variation between the normal and faulty situation and generates residual signal indicating different fault. Simulation results of multiple numbers of statistical tests have been performed for residual based fault diagnosis and threshold calculation. The performance of UKF is then compared with Extended Kalman filter (EKF) with same battery model and fault scenario. The simulation result proves that UKF model responses better and quicker than that of EKF for fault diagnosis.

Managing Fenton-treated sediment with biochar and sheep manure compost: Effects on the evolutionary characteristics of bacterial community.

Fenton oxidation is a widely used method for the fast and efficient treatment of contaminated sediment, but few studies have investigated the management of Fenton-treated sediment for resource utilization. In this study, the evolutionary characteristics of bacterial community composition in Fenton-treated riverine sediment were investigated using 16S rRNA gene sequencing after the incorporation of rice straw biochar and sheep manure compost. The Fenton treatment caused a decline in the relative abundance of Bacteroidetes from 39% to 8% on the 7th day, and using biochar and compost rapidly increased the relative abundance of Firmicutes from 13% to 61% and 57%, respectively. Applying 1.25 wt% biochar after the Fenton treatment contributed to high Shannon diversity indices of 4.80, 4.69, and 4.76 on the 7th, 28th, and 56th day, respectively. The reduced differences of Shannon indexes on the 56th day indicated that the bacterial diversity among different treatments tended to be similar over time. The genera Flavisolibacter and Bacillus were representatively detected on the 7th day in the untreated sediment and Fenton/biochar-treated sediment, respectively. The number of feature bacteria decreased significantly from 88 on the 7th day to 29 on the 56th day. The community functions for the carbon, nitrogen, and sulfur cycles were sensitive to the Fenton-treatment and the subsequent treatment with biochar and compost. This study may provide a useful reference for follow-up work on the remediation of contaminated sediment using advanced oxidation processes, and promote the development of resource utilization of amended sediment.

Cobalt Single Atoms Anchored on Oxygen-Doped Tubular Carbon Nitride for Efficient Peroxymonosulfate Activation: Simultaneous Coordination Structure and Morphology Modulation.

Simultaneous regulation of the coordination environment of single-atom catalysts (SACs) and engineering architectures with efficient exposed active sites are efficient strategies for boosting peroxymonosulfate (PMS) activation. We isolated cobalt atoms with dual nitrogen and oxygen coordination (Co-N3 O1 ) on oxygen-doped tubular carbon nitride (TCN) by pyrolyzing a hydrogen-bonded cyanuric acid melamine-cobalt acetate precursor. The theoretically constructed Co-N3 O1 moiety on TCN exhibited an impressive mass activity of 7.61×105  min-1 mol-1 with high 1 O2 selectivity. Theoretical calculations revealed that the cobalt single atoms occupied a dual nitrogen and oxygen coordination environment, and that PMS adsorption was promoted and energy barriers reduced for the key *O intermediate that produced 1 O2 . The catalysts were attached to a widely used poly(vinylidene fluoride) microfiltration membrane to deliver an antibiotic wastewater treatment system with 97.5 % ciprofloxacin rejection over 10 hours, thereby revealing the suitability of the membrane for industrial applications.

Correction to "Suitable Binary and Ternary Thermodynamic Conditions for Hydrate Mixtures of CH4, CO2, and C3H8 for Gas Hydrate-Based Applications".

[This corrects the article DOI: 10.1021/acsomega.1c06186.].

Suitable Binary and Ternary Thermodynamic Conditions for Hydrate Mixtures of CH4, CO2, and C3H8 for Gas Hydrate-Based Applications.

The selection of suitable hydrate formers and their respective gas composition for high hydrate formation, driving force is critical to achieve high water recovery and metal removal efficiency in the hydrate-based desalination process. This study presents a feasibility analysis on the possible driving force and subcooling temperatures for the binary and ternary mixtures of methane, carbon dioxide, and propane for hydrates-based desalination process. The driving force and subcooling for the gas systems was evaluated by predicting their hydrate formation phase boundary conditions in 2 wt % NaCl systems at pressure ranges from 2.0-4.0 MPa and temperatures of 1-4 °C using modified Peng-Robinson equation of state in the PVTSim software package. The results suggest that the driving force of CH4 + C3H8 and CO2 + C3H8 binary systems are similar to their ternary systems. Thus, the use of binary systems is preferable and simpler than the ternary systems. For binary gas composition, CO2 + C3H8 (70:30) exhibited a higher subcooling temperature of 8.07 °C and driving force of 1.49 MPa in the presence of 2 wt % aqueous solution. In the case of the ternary system, CH4-C3H8-CO2 gas composition of 10:80:10 provided a good subcooling temperature of 12.86 °C and driving force of 1.657 MPa for hydrate formation. The results favor CO2-C3H8 as a preferred hydrate former for hydrate-based desalination. This is attributed to the formation of sII structure and it constitutes 136 water molecules which signifies a huge potential of producing more quantities of treated water.

Enhancing hydrogen peroxide activation of CuCo layered double hydroxide by compositing with biochar: Performance and mechanism.

In this study, CuCo layered double hydroxide/biochar composite (CuCo LDH/BC) was prepared and employed for activating H2O2 to degrade ciprofloxacin (CIP), a common fluroquinolone antibiotic detected in water environment. The as-synthesized catalysts were also comprehensively characterized to study the physiochemical properties. For the catalytic activity, the degradation rate of CuCo LDH/BC to CIP was approximately 1.5 times higher than that of CuCo LDH. The improved catalytic activity can be ascribed to the synergistic effect between CuCo LDH and BC, such as more functional groups, accelerated electron transfer, and varied charge distribution. Meanwhile, CuCo LDH/BC/H2O2 could degrade CIP efficiently in a wider pH range comparing with CuCo LDH/H2O2, and the efficiency was approximately 84.7% at neutral pH within 90 min. The generation of OH, O2- and 1O2 in CuCo LDH/BC/H2O2 system were then verified by electron spin resonance (ESR) technology. The quenching experiments indicated that both non-radical pathway (1O2) and radical pathway (OH, O2-) led to CIP degradation, in which O2- and 1O2 made major contribution. Then, the intermediate products of CIP during catalytic reaction were monitored by high-performance liquid chromatography-mass spectrometry (HPLC-MS), and the environmental risk of these degradation intermediates was tested through seed germination experiments. This study tends to provide valuable information for LDH/BC application in heterogeneous Fenton-like reaction.

Effects of biochar-based materials on the bioavailability of soil organic pollutants and their biological impacts.

Motivated by the unique structure and superior properties, biochar-based materials, including pristine biochar and composites of biochar with other functional materials, are considered as new generation materials for diverse multi-functional applications, which may be intentionally or unintentionally released to soil. The influencing mechanism of biochar-based material on soil organisms is a key aspect for quantifying and predicting its benefits and trade-offs. This work focuses on the effects of biochar-based materials on soil organisms within the past ten years. 206 sources are reviewed and available knowledge on biochar-based materials' impacts on soil organisms is summarized from a diverse perspective, including the pollutant bioavailability changes in soil, and potential effects of biochar-based materials on soil organisms. Herein, effects of biochar-based materials on the bioavailability of soil organic pollutants are detailed, from the perspective of plant, microorganism, and soil fauna. Potential biological effects of pristine biochar (PBC), metal/metal compounds-biochar composites (MBC), clay minerals-biochar composites (CMBC), and carbonaceous materials-biochar composites (CBC) on soil organisms are highlighted for the first time. And possible mechanisms are presented based on the different characters of biochar-based materials as well as various environmental interactions. Finally, the bottleneck and challenges of risk assessment of biochar-based materials as well as future prospects are proposed. This work not only promotes the development of risk assessment system of biochar-based materials, but broadens the strategy for the design and optimization of environmental-friendly biochar materials.

Pyrite-mediated advanced oxidation processes: Applications, mechanisms, and enhancing strategies.

Proper treatment of wastewater is one of the key issues to the sustainable development of human society, and people have been searching for high-efficiency and low-cost methods for wastewater treatment. This article reviews recent studies about pyrite-mediated advanced oxidation processes (AOPs) in removing refractory organics from wastewater. The basic information of pyrite and its characteristics for AOPs are first introduced. Then, the performance and mechanisms of pyrite-mediated Fenton oxidation, electro-Fenton oxidation, and persulfate oxidation processes are carefully reviewed and presented. Natural pyrite is an abundant low-cost heterogeneous catalyst for AOPs, and the slow release of Fe2+ and the self-regulation of solution pH are highlighted characteristics of pyrite-mediated AOPs. In AOPs, the interaction between Fe3+ and pyrite facilitates the Fe2+ regeneration and the Fe2+/Fe3+ cycle. Making pyrite into nanoparticles, assisting by ultrasound and light irradiation, and adding exogenous Fe3+, organic chelating agents, or biochar is effective to enhance the performance of pyrite-mediated AOPs. Based on the analyses of those pyrite-mediated AOPs and their enhancing strategies, the future development directions are proposed in the aspects of toxicity research, mechanism research, and technological coupling.