ACS ES&T engineering最新文献

Over the past 30 years, various methods have been developed for enhancing contaminant removal by zerovalent iron (ZVI), thus accumulating a large amount of quantitative data including the reactivity (k_obs) and electron efficiency (EE). However, comparisons and relationships of the data are still lacking, which hinders the selection and development of ZVI enhancement methods for practical applications. In this review, a large number of k_obs and EE results are systematically summarized and classified into three types based on enhancement mechanisms: regulating iron (hydr)oxide films of ZVI (RIF), accelerating ZVI corrosion (AZC), and coupling of iron reactive species with ZVI (CIRs). Then, the comparisons of k_obs and EE by ZVI along with their enhancement multiples (referred to as R_k and R_EE) were conducted within the context of RIF, AZC, and CIRs. This review identified that in cases where ZVI exhibited low reactivity toward pollutants, it often possessed a high electron efficiency for pollutant reduction and vice versa. Moreover, there existed correlations between lgk_obs (lgR_k) and lgEE (lgR_EE) by ZVI with enhancement methods. These relationships suggest that when both the k_obs (R_k) and EE (R_EE) parameters are known, the other parameter can be predicted to some extent. Finally, this review discussed the effects of the solution chemistry and iron-related compounds on the k_obs (R_k) and EE (R_EE) by ZVI with enhancement methods in detail and outlined their potential research needs in future studies.

Hydrothermal liquefaction can convert biowaste into biocrude oil, and its wastewater byproduct (HTL-WP) has been confirmed with a wide antimicrobial spectrum. Here, we engineered strength-controllable and selective bactericides from HTL-WP via regulation of feedstock and operational temperature. Results showed that HTL-WP from different feedstocks exhibited significantly selective inhibition on Escherichia coli and Staphylococcus aureus. Increasing operational temperature showed varied effects on antibacterial strength of HTL-WP from feedstocks with different components. Thereby, HTL feedstocks and temperatures can be used as switches to prepare strength-controllable and selective HTL-WPs, showing significantly selective inhibition on S. aureus with a maximum inhibition zone of 12.08 mm. Meanwhile, we conducted interaction analysis of HTL-WP characterization, component identification, and conversion path to reveal the changing mechanism of HTL-WP components. The mechanism of controllable intensity and selectivity was analyzed from two aspects: feedstock components and target strains. This study preliminarily establishes an approach for achieving targeted regulation of HTL-WP antibacterial intensity, which has significant reference value for the environmental-friendly reuse and functional targeted regulation of wastewater (liquid byproduct) from biowaste conversion in a specialized engineering-oriented perspective. It also provides novel utilization prospects for the valorization treatment of solid biowaste and promote the development and application of HTL technology.

Piezo-photocatalysis offers a promising, chemical-free approach for the efficient and scalable degradation of micropollutants. However, existing piezo-photocatalysts face challenges in optimizing their performance. In this study, oxygen vacancies (OVs) enriched BiOI nanosheets loaded with Ag nanoparticles (NPs) were synthesized to enhance Trimethoprim (TMP) degradation. The 15% Ag-BiOI demonstrated excellent performance, achieving a degradation efficiency of 97% within 60 min and a rate constant (k) of 0.1157 min^–1, which was significantly greater than the piezocatalytic (0.0476 min^–1) and photocatalytic (0.0784 min^–1) one. The synergistic interaction of OVs and Ag improved O₂ adsorption, creating dual active sites (Ag-OV) that promote the generation of active oxidative radicals, such as singlet oxygen (¹O₂) followed by superoxide radical (^·O₂^–) to degrade TMP. Likewise, OVs in BiOI regulated the piezoelectric field and enhanced TMP degradation by providing ample binding sites for surface interaction. The Ag acted as an electron transport channel, reducing charge carrier recombination, while its surface plasmon resonance effect modified the band gap of BiOI, promoting OVs generation to enhance visible light absorption. The toxicity assessment showed that the plasmon-induced piezo-phototronic effect of Ag-BiOI selectively reduces the toxicity of TMP intermediates by converting them into smaller, less-toxic compounds, proposing an ecofriendly approach for efficient and sustainable micropollutant degradation in wastewater treatment.

Nitrogen doping has been widely used to prepare porous carbon materials for the adsorption of volatile organic compounds (VOCs). However, in the current research, the nitrogen doping process is limited by the raw materials, and it is difficult to achieve simultaneous and precise synergistic regulation of the pore structure, doping quantity, and doping morphology. Inspired by the carbon–nitrogen cycle in nature, the symbiotic community of nitrogen-fixing microorganisms is an important functional group to regulate the elemental cycle. In this study, a novel biological nitrogen fixation incorporation doped method was proposed, i.e., Azotobacter chroococcum (A. chroococcum) is cultivated on the surface of the biochar and catalyzes the conversion of atmospheric nitrogen (N₂) to fixed nitrogen (NH⁴⁺) by nitrogen-fixing enzymes in the body of A. chroococcum, which leads to the formation of bionitrogen and thereby increases the total nitrogen content (0.99%) in the biochar material. The results showed that the content of pyrrole nitrogen in the material was 73.3% and that it possessed a larger specific surface area (1338.21 m²/g) and mesopore (0.499 cm³/g), which greatly improved its adsorption capacity (182.88 mg/g) for ethyl acetate. In addition, in order to elucidate the microscopic adsorption mechanism for enhanced adsorption performance, systematic theoretical calculations of adsorption amount, adsorption energy, and adsorption isotherm were carried out by molecular simulation. This study innovatively achieved green and safe regulation of biomass precursors by nitrogen-fixing bacteria without increasing the nitrogen source and provided a theoretical basis and technical methods to improve the quality and efficiency of the VOC adsorption materials.

Acid mine drainage (AMD) is a significant environmental challenge, and its treatment can be expensive and complicated. Acidithiobacillus could accelerate the rate of AMD formation by 5–6 orders of magnitude. Acidithiobacillus ferrooxidans (A. ferrooxidans) is the model species of Acidithiobacillus. We initially tried to use the biogas slurry as an organic additive to prevent AMD formation. We determined the essential inhibitory components of the biogas slurry as organic acids (acetic acid (AA), a typical example). The results revealed that AA (≥50 ppm) prevented A. ferrooxidans from forming AMD. The transcriptomic and untargeted metabolomic evaluation found 324 differentially expressed genes and 35 significantly transformed metabolites. Combinatorial omics analysis showed that the presence of AA significantly inhibited the membrane biogenesis, Fe²⁺, and RISC metabolism pathways, reducing energy metabolites such as Fe³⁺ and SO₄^2–. Furthermore, AA treatment induced A. ferrooxidans defense mechanisms and overconsumed its internal carbon sources. These findings proved that biogas slurry had a significant inhibitory effect on key microorganisms in highly acidified mineral soils and provided a scientific foundation for the prevention of acidification and the ecological restoration of newly mined areas.

Peroxydisulfate (PDS)-based processes are an effective approach for eliminating emerging organic micropollutants (MPs) in (waste)water treatment. Iron-based homogeneous systems are known for their availability, technical and economic feasibility, and relatively nontoxic nature; however, these systems suffer from drawbacks that limit their application. Herein, an iron-based ternary chalcogenide material, Fe₂GeS₄ nanocrystals (FGS NCs), was used to activate PDS for the removal of bisphenol A (BPA). The FGS/PDS system achieved complete removal of BPA at circumneutral pH with a high reaction stoichiometric efficiency (7.8%), outperforming common PDS activators, such as Fe(II), pyrite, zerovalent iron, and black iron oxide. The synergistic enhancement in PDS activation could be attributed to the improved Fe(III)/Fe(II) cycle due to the reduced sulfur and divalent germanium species in the olivine FGS NCs. This finding was confirmed by mechanistic investigations and chromatographic, spectroscopic, and density functional theory studies. Both high-valent iron-oxo (Fe^IV) species (dominant) and sulfate radicals (auxiliary) contributed to BPA transformation, where the solution chemistry (pH, temperature, substrate dose, and anions) influenced the removal of BPA from the FGS/PDS system. Evaluation of the performance of the FGS/PDS system in real water matrices (river water, groundwater, and secondary effluents) revealed its long-term stability and efficiency in removing multiple MPs, including acetaminophen, N,N-diethyl-m-toluamide, perfluorooctanoic acid, 4-chlorophenol, benzotriazole, and ethylparaben. Overall, these findings highlight the potential of FGS/PDS for effective MPs removal in (waste)water treatment.

Thermal sintering/melting technology is a hot topic for the treatment of municipal solid waste incineration with fly ash (FA) nowadays. Most attention is focused on the safety of the treated FA, but seldom focus is put on the separation of thermally volatile metal salts. In this work, we investigated a thermal-sediment control method for effective separation of Zn, Pb, Cu, Cd, K, and Na from FA. Volatilized solids collected from different sediment zones (according to their distances from the FA source) are compared in detail under controlling gas flow rates and heating temperatures. As a result, 52 wt % of Cd and 54 wt % of Pb are first separated in different zones, and 53 wt % of Zn and 52 wt % of Cu are second separated in different zones. Finally, Na and K are recovered together. Pb and Zn purities are as high as 93–94 wt %. What is more, recovery rates of metals from FA follow the order of 90 wt % (Pb) > 83 wt % (Zn) > 81 wt % (Cd) > 77 wt % (Cu) > 73 wt % (Na) > 66 wt % (K). A volatilization-condensation mechanism is put forward to explain the separation of different metal salts. The main result of this work helps the development of the “zero-waste city” concept, which is also in favor of green development and circular economy.

Substituting chemical fertilizers with compost is anticipated to facilitate the disposal of organic waste and mitigate nonpoint source pollution. However, research investigating the impact of diverse-compost utilization on the chemical reactivity of soil at the molecular-level remains lacking. Herein, the quantification and identification of molecular-scale redox sites and intermolecular interactions of soil dissolved organic matter (DOM) using diverse composts during a crop rotation cycle were investigated using the unified theoretical modeling approach VSOMM2 and Schrödinger. Results showed that compost use considerably altered the molecular weight and composition of soil DOM. In particular, we successfully optimized the validity coefficient of the unit model’s molecular number to construct 38 molecular models of DOM molecules to identify and quantify the distribution of redox sites and intermolecular interactions within soil DOM molecules. Moreover, the distinct roles of different composts in modulating redox molecules within the soil DOM were determined during a crop rotation cycle. The application of cow manure compost considerably increased the quinone, Ar–COOH, and Ar–SH contents in Model(EAC+), while application of food waste compost enhanced the Ar–OH and Ar–NH₂ in Model(EDC+). Finally, rotatable bonds, cation−π interactions, aromatic H-bonds, π-stacking, and salt bridges were identified to facilitate electron transfer within the redox molecules of soil DOM, which can be further enhanced via compost use. The findings of this study provide insights into the environmental biochemical reactions involving microcatalysts, metal reduction fate, pollution fate, and molecular composition of soil, providing a theoretical basis for enhancing soil reactivity using organic fertilizers instead of chemical fertilizers.

Heterojunction-based photocatalysts are receiving tremendous scientific attention for eliminating consumer-derived micropollutants from aqueous environments. However, the inherent difficulty in recovering photocatalysts following treatment, due to their application in powder form, precludes their widespread use. Herein, a self-supporting and lightweight three-dimensional (3D) graphitic carbon nitride (g-C₃N₄)/tungsten disulfide (WS₂)/agarose aerogel (GCWAA) was constructed via a facile and scalable radial freeze-casting approach. The as-synthesized 3D GCWAA proved extremely promising for the photocatalytic removal of three broad-spectrum antibiotic pollutants (ABPs), viz., tetracycline (94%), sulfamethoxazole (97%), and ofloxacin (96%), within 90 min of visible light irradiation in the batch regime. The enhanced photocatalytic performance of 3D GCWAA can be attributed to a Z-scheme electron flow from g-C₃N₄ to WS₂ in the aerogel, as inferred from electronic band structure characterization. To further demonstrate the practical utility of the composite aerogel in water and wastewater treatment systems, the continuous flow photocatalysis of ABPs over 3D GCWAA was systematically studied. Specifically, the influence of several noteworthy operational parameters, such as flow rate, solution pH, and the presence of interfering ions was comprehensively investigated. Interestingly, under optimized conditions, GCWAA achieved a remarkable average removal efficiency of 95% for ABPs in continuous mode, with minimal loss of activity over time. More attractively, GCWAA exhibited decent photocatalytic performance for treating a ternary mixture of ABPs in both freshwaters and wastewaters in the continuous flow reactor. The results of this study showcase the ultimate lab-scale demonstration of the photocatalytic potential of 3D GCWAA for the degradation of emerging contaminants, paving the way for future scale-up.

A complete analysis of a catalytic pyrolysis scheme, evolved to a combined in situ thermal cracking/steam reforming scheme, to valorize nonrecyclable plastic waste is presented. The study aims to analyze the three fractions obtained, focusing on the production of a hydrogen-rich gaseous fraction with industrial interest. The optimization in terms of hydrogen generation is carried out using various ruthenium-containing catalytic systems prepared by a facile preparation method. Several catalytic systems were tested, all ruthenium-containing materials interacting with g-C₃N₄, ZSM5, high-surface-area carbon, and TiO₂ as active supports. In the combined reaction scheme defined by catalytic cracking/steam reforming reactions at 550 °C of the pyrolysis gases using a RuO₂/TiO₂ composite system in a one-step reaction system, 270.7 mmol of hydrogen (13.5 mmol g^–1 of plastic waste) were obtained, representing an increase of 227.6 mmol in comparison with the traditional thermochemical process. The contribution is completed with a characterization scheme of the obtained product fractions and composite catalysts, including a postreaction analysis, which allowed the identification of the main properties (catalysts) and operating conditions (setup) to optimize the process.