The electrochemical catalytic reduction of nitrate to ammonia presents a promising strategy for simultaneous addressing water purification needs and contributing to the development of ammonia-based energy. However, previous electrochemical catalysts predominantly utilized precious metals, which suffer from scarcity and high cost. Meanwhile, conventional copper-based catalysts tend to cause nitrite accumulation. This experiment synthesized a multi-active-site catalyst Cu + Cu2O/CP-40 using a simple synthesis method and low-cost materials. The catalyst exhibited a nitrate removal rate of 94.01% and an ammonia selectivity of 97.86%, surpassing the Cu/CC catalyst synthesized on carbon cloth by 3.55% in nitrate removal and 24.27% in ammonia selectivity. The reaction mechanism was elucidated through electron paramagnetic resonance (EPR) and masking experiments, which revealed that the catalyst promotes nitrate reduction predominantly via a direct electron transfer pathway. Furthermore, the combined use of X-ray photoelectron spectroscopy (XPS) and electron paramagnetic resonance (EPR) provided confirmatory evidence for the existence of oxygen vacancies. DFT calculations further elucidated a triple synergistic mechanism: Cu2O enhanced initial adsorption; the Cu(111) facet drove the reaction forward by promoting *NO2 hydrogenation; and oxygen vacancies substantially accelerated *HNO2 deoxygenation by weakening the N-O bond. Finally, this cathode material demonstrated excellent performance in 10 cycles of experimental testing, achieving nitrate removal rates exceeding 85% and ammonia selectivity greater than 94%. By developing a novel electrochemical strategy for nitrate-to-ammonia conversion, this study not only demonstrates a specific technical route but also provides significant impetus for the advancement of the entire field.

Hexavalent chromium (Cr(VI)) is quite poisonous, strongly cancer-causing, and mutagenic pollutant that seriously endangers both human health and ecological environments. Therefore, developing efficient, economical, and green techniques for removing Cr(VI) represents an urgent priority. Conventional treatment methods suffer from drawbacks of slow kinetics and poor stability. Hence, achieving effective elimination of Cr(VI) while simultaneously promoting the resource utilization of solid waste constitutes a key challenge addressed. To address this, a waste-treat-waste strategy to use coal gangue (CG) and cotton stalk (CS) to successfully prepare a porous adsorbent rich in carboxyl functional groups through high-temperature activation and carboxylation. The material exhibits an exceptionally high specific surface area of up to 1840.60 m2·g−1 with a well-developed porous structure. The adsorption efficiency for Cr(VI) reached 235.68 mg·g−1, accompanied by rapid adsorption kinetics and excellent regeneration performance. The superior performance of the material stems from its unique structure and composition, the large surface area and porous structure of this material can make Cr(VI) quickly aggregate. Also, the surface carboxyl groups can undergo protonation to form -COOH2+ sites, which electrostatically attract Cr(VI), further enhancing their accumulation. The inherent phenolic hydroxyl groups within the material can reduce Cr(VI) to Cr(III), while the surface carboxyl groups provide abundant metal coordination sites, as further confirmed by XPS spectra analysis. Subsequently, Cr(III) forms stable complexes with COO−, achieving chromium immobilization. This study introduces an innovative material and method, which can not only effectively remove Cr(VI), but also open up a new pathway for the high-value utilization of CG.

Anaerobic digestion (AD) of swine manure to convert organic components into methane as much as possible is a promising treatment method, yet it faces challenges such as the difficulty in hydrolyzing solid organic matter and ammonia inhibition. This study aimed to find the effect of iron (hydr) oxides on methane production from AD of swine manure, and the mechanism of iron (hydr) oxides influencing methane production. The results showed that 0.5 g/L of hematite, goethite and ferrihydrite could promote the production of methane, which was 22.8 %, 39.4 %, and 56.3 % higher than that of the control group, respectively. These iron (hydr) oxides experiment groups showed high hydrolysis, acidogenesis and methanogenesis rates. Especially, goethite and ferrihydrite were beneficial to iron ammonia oxidation process (Feammox) and alleviated the ammonia inhibition of methanogens. However, hematite and its high crystallinity avoided the maintenance of the Feammox process. From the microorganism point of view, iron (hydr) oxides enriched bacterial communities related to organic substrate degradation, reductive iron bacteria (FeRB), and ammonia-tolerant methanogens. In conclusion, Feammox triggered by iron (hydr) oxides helps to strengthen anaerobic biochemical process, especially reduce the impact of ammonia inhibition, thus contributing to methane production. These insights provided new viewpoint that using iron (hydr) oxides to improve the biochemical metabolism process of swine manure AD as well as the methane conversion rates.

Adjusting the local structure of single-atom catalysts (SACs) via substrate microstructure engineering is a promising yet challenging strategy to enhance Fenton-like activity. Herein, SACs with embedded FeN4 and nonembedded FeN2+2 coordination were designed through substrate microstructure regulation. FeN2+2 configuration markedly improved PAA activation, increasing the reaction rate constant (kobs) of the Fenton-like reaction by 1.35-fold compared to FeN4. Unlike the single-site activation of FeN4, FeN2+2 disrupts the dx2-y2 and dz2 orbital balance in Fe 3d orbitals, shifting the d-band center closer to the Fermi level. This optimizes the adsorption and decomposition of PAA to complete the dual activation pathway to facilitate the simultaneous generation of singlet oxygen (1O2) and hydroxyl radical (center dot OH) via a low-energy barrier process. This work provides a new mechanistic understanding of SAC-based Fenton-like catalysis and offers design insights for expanding SACs applications in advanced oxidation processes and environmental remediation.

High ammonia nitrogen and low electron transfer rate leaded to unfavorable methane generation efficiency during pig manure anaerobic digestion. This study aimed to find the effect of ferrihydrite on methane production from anaerobic digestion of pig manure, and the mechanism of ferrihydrite influencing methane production. The results showed that 0.1-0.5 g/L ferrihydrite could promote the production of methane, which was 46.9-84.8 % higher than that of the control group. The ferrihydrite experiment groups showed high hydrolysis, acidogenesis and methanogenesis rates. Ferrihydrite was beneficial to Feammox process and alleviated the ammonia inhibition of methanogens. From the microorganism point of view, it showed higher expression of functional genes related to hydrolysis, acidogenesis and methanogenesis process. These understandings will help to reveal how the ferrihydrite affect the microorganisms and substrates on the biochemical metabolism process of anaerobic digestion of pig manure, so as to provide effective guidance for higher methane conversion.

Coal gangue (CG) is a kind of widespread industrial waste, its large accumulation brings great challenges to the environment. Thus researchers has been widely concerned the efficient utilization of CG. At the same time, fluoroquinolone antibiotics contaminants, such as ciprofloxacin (CIP), are difficult to degrade, have low environmental capacity and wide migration range, and have constantly detected in various kinds of water bodies, and are a kind of toxic organic pollutant. In this study, the CG/NiO-3 composite catalyst was synthesized by chemical precipitation combined with high temperature pyrolysis. Under the conditions of 20.0 mg L -1 CIP concentration, 0.4 g L -1 catalyst dosage and initial pH = 7.0, 180 min of sunlight was simulated, and the removal efficiency reached 87.48%. Through scanning electron microscopy (SEM), X-ray diffraction (XRD), fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), nitrogen adsorption -desorption, electron paramagnetic resonance (EPR), found that the degradation efficiency of CG/NiO-3 composites catalyst is improved because the hydroxyl group on the surface of CG promotes the generation of free radicals through the adsorption of oxygen and the introduction of CG increases the specific surface area. It provides more active sites while promoting the interfacial charge transfer and increasing the absorption of sunlight. Therefore, this work provides reference significance and theoretical basis for the resource utilization of CG and the treatment of organic pollutants.

Heavy metal Cr(VI) in water body has attracted extensive attention due to its carcinogenicity, teratogenicity and mutagenicity. In this study, magnetic walnut shell biochar (Fe3O4@WSB-n) were prepared from walnut shell (WS) by impregnation (to destroy the wooden structure of walnut shell), alkali activation and hydrothermal synthesis. Not only solved the problem of difficult separation of adsorbent, but also realized the reuse of envi-ronmental waste. Results manifest that Fe3O4@WSB-1 has a hierarchical honeycomb structure with a specific surface area of 914.01 m2 g-1. And the adsorption process of Cr(VI) on Fe3O4@WSB-1 belongs to monomolecular chemisorption, and the maximum adsorption capacity is reached to 230.63 mg g-1 (0.01 g, 30 mL pH = 2.0, 25 degrees C). Adsorption capacity of Fe3O4@WSB-1 for Cr(VI) can still keep 66.85 mg g-1 after 5 cycles. The XPS and FT-IR results show that the oxygen-containing functional groups play a significant role in the adsorption process, and the magnetic centers further promote the reduction of Cr(VI) through reducibility of Fe2+. Due to efficient conversion of hardwood structures, high stability in solution and easy recovery, magnetic biochar is suitable for practical wastewater treatment.

The heavy metal Cr(VI) in water body has attracted extensive attention due to its carcinogenicity, teratogenicity and mutagenicity. In this study, magnetic walnut shell biochar (Fe3O4@WSB-1) is prepared from walnut shell by impregnation (to destroy the wooden structure of walnut shell), alkali activation and hydrothermal synthesis. Those methods not only solved the problem of difficult separation of adsorbent, but also realized the reuse of environmental waste. The results show that Fe3O4@WSB-1 has a hierarchical honeycomb structure with a specific surface area of 914.01 m2·g-1. Results demonstrate that the adsorption process of Cr(VI) on Fe3O4@WSB-1 belongs to monomolecular chemisorption, and the maximum adsorption capacity is reached to 230.63 mg·g-1. Adsorption capacity of Fe3O4@WSB-1 for Cr(VI) can still keep 66.85 mg·g-1 after 5 cycles. The XPS and FT-IR results show that the oxygen-containing functional groups play a significant role in the adsorption process, and the magnetic centers further promote the reduction of Cr(VI). Due to the excellent characteristics of high stability in solution and easy recovery, magnetic biochar is suitable for practical wastewater treatment.

Abstract different sand burial depths on seed germination, seedling emergence, growth and biomass allocation were studied to provide a scientific basis for further control of X. spinosum. Six sand burial depths (1, 2, 3, 5, 7 and 9 cm) were established to explore the response of X. spinosum seed germination and seedling growth to sand burial. The first emergence time, peak emergence time, emergence rate, seedling growth height, biomass and biomass distribution of X. spinosum seeds had significant effects at different sand burial depths (P < 0.05). The X. spinosum seeds had the highest emergence rate (71.5%) at 1 cm sand burial and the maximum seedling height (7.1 cm). As sand burial depth increased, the emergence rate and seedling height gradually decreased, and the emergence rate (12.25%) and seedling height (2.9 cm) were lowest at 9 cm sand burial. The root length at 9 cm depth (13.6 cm) was significantly higher than that at other sand depths (P < 0.05). The sand burial depth affected the biomass accumulation and distribution of X. spinosum. As sand burial depth increased, the root biomass and rhizome ratio increased, and the most deeply buried seedlings allocated more biomass for root growth. The optimal sand burial depth for seed germination and seedling growth of X. spinosum was 1–3 cm, and high burial depth (5–9 cm) was not conducive to the germination and growth of X. spinosum seedlings. For prevention and control of X. spinosum, we suggest deeply ploughing crops before sowing to ensure X. spinosum seeds are ploughed into a deep soil layer.

Sophora alopecuroides is known to produce relatively large amounts of alkaloids; however, their ecological consequences remain unclear. In this study, we evaluated the allelopathic potential of the main alkaloids, including aloperine, matrine, oxymatrine, oxysophocarpine, sophocarpine, sophoridine, as well as their mixture both in distilled H2O and in the soil matrix. Our results revealed that all the alkaloids possessed inhibitory activity on four receiver species, i.e., Amaranthus retroflexus, Medicago sativa, Lolium perenne and Setaria viridis. The strength of the phytotoxicity of the alkaloids was in the following order: sophocarpine > aloperine > mixture > sophoridine > matrine > oxysophocarpine > oxymatrine (in Petri dish assays), and matrine > mixture > sophocarpine > oxymatrine > oxysophocarpine > sophoridine > aloperine (in pot experiments). In addition, the mixture of the alkaloids was found to significantly increase the IAA content, MDA content and POD activity of M. sativa seedlings, whereas CTK content, ABA content, SOD activity and CAT activity of M. sativa seedlings decreased markedly. Our results suggest S. alopecuroides might produce allelopathic alkaloids to improve its competitiveness and thus facilitate the establishment of its dominance; the potential value of these alkaloids as environmentally friendly herbicides is also discussed.

Co4S3–Co9S8 nanoparticles with abundant interfaces hosted on reduced graphene oxide were synthesized via a monomolecular pyrolysis strategy to boost catalytic activity.

刺苍耳(Xanthium spinosum)为伊犁河谷地区常见的恶性入侵植物,研究其幼苗在氮沉降下的生长、分配特征,将有助于了解该物种对氮沉降的响应规律.实验设置4个氮沉降水平(0、0.18、0.72、2.88 g N·m-2·week-1),探索刺苍耳幼苗的形态特征、构件的生物量及生物量分配的响应特征.结果 表明:(1)相对于对照组和低沉降组,中等水平的氮沉降(0.72 g N·m-2·week-1)下幼苗的主根伸长、株高增高、叶片数增多、基径加粗、刺增多;高氮沉降(2.88 g N·m-2·week-1)下,除主根长显著伸长外,幼苗的株高、叶片数、基径和刺数均显著降低;(2)在高氮环境中,根、茎和叶的生物量均显著下降,但根生物量比和根冠比则显著增高;(3)幼苗的生长对不同氮沉降水平具有时间响应特征,中氮条件下的幼苗在取样中期表现为生长缓慢,在末期则迅速生长,而高氮条件下则恰好相反.这些结果表明,中等水平的氮沉降能在一定程度上促进刺苍耳幼苗的生长,提高其潜在的入侵危害性,但高氮沉降下则不利于入侵.

AbstractTo evaluate the potential value of Seriphidium terrae‐albae (Krasch.) Poljakov essential oil as bioherbicide, its chemical composition as well as phytotoxic activity was investigated. Seventeen compounds were identified via GC/MS, representing 98.1 % of the total oil, and the most abundant constituents were α‐thujone (43.18 %), β‐thujone (16.92 %), eucalyptol (17.55 %), and camphor (13.88 %). Phytotoxic assay revealed that the essential oil as well as its major constituents exhibited inhibitory activity on root and shoot growth of receiver plants in a dose‐dependent manner. When the concentration reached 20 μg/mL, root length of Amaranthus retroflexus was reduced to 31.3 %, 70.6 %, 36.9 %, and 66.6 % of the control, respectively, when treated with α‐thujone, eucalyptol, camphor, and the mixture of these compounds; meanwhile, root length of Poa annua was 3.0 %, 24.2 %, 0 %, and 4.4 % of the control when the same chemicals were applied. On the other hand, the essential oil showed a much stronger activity. At 1.5 μL/mL, root and shoot length of A. retroflexus and P. annua were reduced to 0.65 %, 0.5 %, and 1.53 %, 1.51 % of the control, respectively, and seed germination of A. retroflexus and P. annua was completely inhibited when the oil concentration reached 3 μg/mL and 5 μg/mL, respectively. This is the first report on the chemical composition of the essential oil of S. terrae‐albae, and our results indicated that it has the potential to be further exploited as a bioherbicide.

The aim of this study was to identify bioactive compounds from leaves of the invasive plant Xanthium spinosum and assess their phytotoxic activity. Activity-guided fractionation led to the isolation of 6 bioactive compounds: xanthatin (1), 1α,5α-epoxyxanthatin (2), 4-epiisoxanthanol (3), 4-epixanthanol (4), loliolide (5) and dehydrovomifoliol (6). Of them, compounds 2⁻6 were isolated from the X. spinosum for the first time. The structures of 1⁻6 were elucidated on the basis of extensive NMR studies and ESI-MS measurements as well as comparison with literature data. All of compounds were evaluated for their phytotoxic activity. Among them, compounds 1⁻4 exhibited stronger activity on 2 receiver plants compared with the other 2 compounds, with xanthatin (1) being the most potent compound, which suppressed root growth of the dicot plant Amaranthus retroflexus by 32.5%, 39.4%, 84.7% when treated xanthatin (1) at 5, 20, and 100 µg/mL, while for the monocot plant, root growth was inhibited by 14.7%, 28.0%, and 40.0%, respectively. Seedling growth was nearly completely inhibited when the concentration of xanthanolides increased to 500 µg/mL, whereas there was still some seedling growth when loliolide (5) and dehydrovomifoliol (6) were applied at the same concentration. Dehydrovomifoliol (6) did not negatively affect seedling growth of P. annua at all tested concentrations, and root length was still 42.0% of the control when the highest concentration 500 µg/mL was used. This is the first report of the phytotoxicity of 1α,5α-epoxyxanthatin (2), 4-epiisxanthanol (3) and 4-epixanthanol (4). These compounds have the potential to be utilized as natural herbicides, especially 4-epiisoxanthanol (3), which exhibited significant selective activity between the dicot and monocot plants. On the other hand, whether these bioactive substances serve as allelochemicals to facilitate the invasion success of X. spinosum needs to be further studied.

The allelopathic effect of aqueous and ethanol extracts of different plant parts ( i. e. root,stem, leaf,fruit) of the invasive plant Xanthium spinosum L. was evaluated at 0. 05 g/mL on Setaria glauca,Lo-lium multiflorum,Lactuca sativa and Brassica chinensis. The results showed that among the aqueous ex-tracts,leaf extract exhibited the most potent inhibitory activity,which suppressed the germination rate and root length of S. glauca,L. multiflorum,L. sativa,B. chinensis by 36. 4%,17. 9%,25. 8%,18. 7% and 62. 7%,68. 4%,26. 8%,34. 7%,respectively. The ethanol extract of leaves inhibited root length of S. glauca,L. multiflorum,L. sativa and B. chinensis by 92. 5%,89. 3%,36. 7% and 48. 4%,respectively. Furthermore,root and fruit extracts also showed significant allelopathic activity against three plants,inhibi-ting root growth by 21. 2%—46. 4%( except B. chinensis) and 48. 0%—54. 8%( except L. multiflo-rum) ,respectively. Overall,the inhibitory activity of the ethanol extracts was stronger than the aqueous ex-tracts. This study reveals that the major active allelochemicals are present in the leaf ethanol extract.

刺苍耳是恶性入侵杂草,为了研究其种子中的化感活性物质,对种子的95％乙醇浸提物,经石油醚、氯仿、正丁醇分级萃取,研究不同萃取组分(浓度为1 mg/mL)对小白菜、莴苣、黑麦草、金色狗尾草4种植物的化感作用强度.研究结果表明,石油醚萃取相对小白菜、莴苣、金色狗尾草3种植物根长生长表现出了显著的化感促进作用,其强弱顺序为小白菜>莴苣>金色狗尾草;而氯仿萃取相对小白菜、莴苣、黑麦草3种植物根长、苗高生长都表现出了很明显的化感抑制作用,其强弱顺序为莴苣>小白菜>黑麦草;正丁醇萃取相和水相对4种植物幼苗的根长无显著影响.表明几种受试植物对相同萃取相组分的敏感性有显著差异,且刺苍耳中的活性物质主要集中在氯仿相和石油醚相;刺苍耳种子氯仿萃取相具有很强的抑制活性,可进一步从中分离提取活性物质.

为探明刺苍耳(Xanthium spinosumL.)各时期(幼苗期、花蕾前期、成熟期)的化感作用,采用生物测定法研究刺苍耳各时期水提液对小白菜(BrassicachinensisL.)、莴苣(Lactuca sativaL.)、黑麦草(Lolium multiflorumL.)、金狗尾草(Setaria glaucaL.)4种植物幼苗生长的影响.结果表明:(1)刺苍耳成熟期全株水提取液对小白菜根长、苗高的影响表现为"低促高抑"的效应;当水提液浓度为10 mg·mL-1时,对小白菜、莴苣、黑麦草、金狗尾草的根长和苗高生长抑制率分别在39.25％—69.43％和13.17％—58.02％之间.(2)刺苍耳花蕾前期全株水提液在同样浓度10 mg·mL-1时,对白菜、莴苣、黑麦草、金狗尾草的根长和苗高生长表现出完全的抑制作用,并且在浓度5 mg·mL-1时对4种植物根长的抑制率分别在36.48％—72.71％之间,远高于刺苍耳成熟期在同浓度下的抑制作用.(3)刺苍耳幼苗期全株水提液在浓度为5 mg·mL-1、10 mg·mL-1时对4种植物表现出了完全的抑制作用.在浓度2.5 mg·mL-1时,对4种植物根长的抑制率分别在52.96％—65.67％之间,抑制率也远高于同浓度下的刺苍耳成熟期和花蕾前期.刺苍耳各时期的化感作用是客观存在的,在同样浓度下,刺苍耳幼苗期水提液对植物的抑制作用强于另两个时期,可能是由于种子萌发时产生了较多的化感物质,以便尽早排挤其它伴生植物,占据生态优势.