PROCEEDINGS OF THE COMBUSTION INSTITUTE
·
2014
·
IF 3.828
Huan Liu,Qiang Zhang,Hongyun Hu,Peng Liu,Xiaowei Hu,Aijun Li,Hong Yao
Thermal disposal of sewage sludge is likely to cause serious nitrogen related environmental pollution since it contains considerable amounts of nitrogen, the species of which are quite different from those in coal. Considering that lime (CaO) is a widely applied chemical conditioner for sewage sludge dewatering, this study investigated the catalytic role of conditioner CaO in nitrogen transformation during sewage sludge pyrolysis in a drop-tube/fixed-bed furnace at 873 K, 1073 K and 1273 K, respectively. Model compounds were also used to further clarify the mechanisms involved. According to the results, conditioner CaO increased the fraction of more stable protein-N as well as amine-N. The solid phase reactions produced CaC x N y , thus enhancing the nitrogen retention in char. Correspondingly, decreased relative ratio of nitrates-N/nitrites-N and oxygenated organics in sludge conditioning contributed to less NO emission. Meanwhile, conditioner CaO promoted the conversion of HCN to NH 3 , as well as the deamination of proteins, amine, and other N-containing compounds in tar and char, leading to increased NH 3 generation. Subsequently, CaC x , the decomposition product of CaC x N y , captured NH 3 , driving down the final production of NH 3 . In addition, Ca(OH) 2 hindered the transformation of nitrile-N in char to HCN, decreasing HCN generation. CaO reacted with HCN, further reducing its releasing amount. CaC x N y derived from different sources decomposed to produce a very large amount of N 2 . These indicate that reusing conditioner CaO is a promising strategy for reducing the productions of NO x precursors efficiently and increasing the formation of non-polluting N 2 dramatically.
研究领域:
环境科学
·
能源与燃料
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DOI
高影响因子
ACS Omega
·
2024
·
IF 3.7
Xinyue Jiang,Defu Liu,Guodong Jiang,Yuqun Xie
A technique for monitoring chemical oxygen demand (COD), total nitrogen (TN), ammonia (N-NH4), and phosphate (P-PO4) in surface water with a targeted signal multielectrode system (Cu, Ir, Rh, Co(OH)2, and Zr(OH)4 electrodes) is proposed for the first time. Each water quality index is specifically detected by at least two electrodes with distinct selectivity sensing mechanisms. Cyclic voltammetry and electrochemical impedance measurements are employed for multidimensional signal acquisition, complemented by normalization and Least Absolute Shrinkage and Selection Operator (LASSO) for principal feature extraction and dimension reduction. Multiple linear regression (MLR), partial least-squares (PLS), and eXtreme Gradient Boosting (XGBoost) were employed to evaluate the established prediction model. The precisions of the multielectrode system are ±10%/±5 ppm of COD, ±10%/±0.2 ppm of TN, ±5%/±0.1 ppm of N-NH4, and ±5%/±0.01 ppm of P-PO4. The analysis time of the multielectrode system is reduced from hours to minutes compared with traditional analysis, without any sample pretreatment, facilitating continuous online monitoring in the field. The developed multielectrode system offers a feasible strategy for online in situ monitoring of surface water quality.
研究领域:
环境科学
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分析化学
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产品关联
DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS
·
2025
·
IF 4.6
Zhongyou Que,Xingyu Li,Lin Zhang,En Mei,Chenguang Guo,Haishen Sun,Junming Liu,Mingli Qin,Gang Chen,Xuanhui Qu
The in-situ synthesis of finely dispersed second phases with high melting points and thermal stability is an effective strategy to address the high cost, inadequate high-temperature performance, and reduced thermal conductivity of tungsten‑rhenium (W Re) alloys. In this study, we employed a novel nitridation-denitridation (NDN) process to synthesize W-10Re-HfN nano powder, in-situ synthesizing nano HfN particles to strengthen and toughen the W Re alloy. Compared to W 10Re, the hardness of W-10Re-2HfN increased significantly from 604 HV to 977 HV, the compressive strength was improved from 1366 MPa to 2181 MPa, and fracture strain increased from 3.6 % to 32 %. Statistical results indicate that HfN particles within the grains or with sizes below ∼36 nm exhibit completely coherent interfaces with the W Re matrix. By combining in-situ synthesis of nitrides with a two-step sintering process, we successfully retained 63 % of HfN particles within the grains and controlled the average particle size of HfN particles at the grain boundaries to be 36 nm, thereby enhancing grain boundary strengthening and coherent interface strengthening. This study innovatively incorporates finely dispersed and highly stable nitrides into W Re alloys through in-situ doping, offering a novel strategy for reinforcing refractory metals.
研究领域:
材料科学
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机械工程
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产品关联
DOI
高影响因子
Processes
·
2024
·Vol. 12
·期 12
·2768
·
IF 2.8
Junyi Chen,Yuchi Luo,Junda Zhang,Zexuan Lu,Yitong Han,Xiangxin Chen,Mingkui Li,Hanyun Fan,Xipeng Wei
In acidic groundwater, effectively removing both ammonia nitrogen (NH4+-N) and nitrate nitrogen (NO3−-N) poses a challenge. This study focused on studying the removal of NH4+-N and NO3−-N combined contaminations by zero-valent iron (ZVI) combined with microbial agents in both laboratory and field pilot-scale studies. Laboratory experiments showed that ZVI could reduce the denitrification stage from 15 days to 10 days by increasing solution pH and improving NO3−-N reduction efficiency. In a field pilot test (at Qingyuan, Guangdong Province, China), high-pressure injection pumps were used to inject alkaline reagents to raise the pH to 7~8. Meanwhile, compressors were applied to aerate the groundwater to increase the dissolved oxygen (DO) concentration above 2 mg·L−1. Subsequently, microbial agents of nitrobacteria were injected to initiate aerobic nitrification. As the DO level dropped below 2 mg·L−1, agents of micro-ZVI and denitrifying bacteria were injected to stimulate autotrophic denitrification. Intermittent aeration was employed to modify the redox conditions in the groundwater to gradually eliminate NH4+-N and NO3−-N. However, due to the effect of the low-permeability layers, adjustments in the frequency of remediation agent injection and aeration were necessary to achieve removal efficiencies exceeding 80% for both NH4+-N and NO3−-N. This work aims to overcome the limitations of microbial remediation methods in the laboratory and the field and advance nitrogen pollution remediation technologies in groundwater.
研究领域:
环境科学
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微生物学
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产品关联
DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2020
·Vol. 44
·期 38
·16320-16328
·
IF 3.288
Yuanyuan Yang,Wenting Guo,Yunpu Zhai,Qianwei Jin,Hao Zhao,Ruiqin Zhang,Yonggang Liu
Typical non-metallic semiconductor carbon nitride (CN) has enormous potential in the field of photocatalysis, but the easy recombination of the photo-generated charges severely limits its practical applications. Herein, oxygen-doped and nitrogen vacancy co-modified carbon nitride (ODCN) was prepared by simple reduction and oxidation treatments. The experimental results show that the modified CN can effectively enhance the photocatalytic activity, indicating that there is a synergy between oxygen doping and nitrogen vacancy. The photocatalytic hydrogen generation rate of ODCN is 364 μmol g−1 h−1, which is higher than that of bulk CN, nitrogen vacancy-modified carbon nitride (DCN) and oxygen-doped modified carbon nitride (OCN). As a consequence, our work provides a neoteric idea for the co-modification of carbon nitride by a variety of methods, which can significantly improve the photocatalytic activity of carbon nitride and is expected to be applied in practical applications.
研究领域:
材料科学
·
能源科学
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产品关联
DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2021
·Vol. 45
·期 28
·12669-12677
·
IF 3.591
Yu Jiang,Chen Yang,Qian Yao,Yurong Deng,Jingjing Yang,Yanjun Liu,Zhuozhi Ouyang,Weilin Huang,Zhi Dang
To clarify the function of the nitrogen-containing structures on the adsorption of heavy metals, nitrogen-enriched biochars (NBCs) mainly composed of pyrrolic, pyridinic, and graphitic nitrogen were prepared to investigate the interaction mechanism with Cd(II). The results of batch experiments revealed that the saturated Cd(II) adsorption capacities of Pr-NBC, Pd-NBC, and Gp-NBC were 12.68, 24.04, and 35.95 mg g−1 respectively. The strongest adsorption ability was found for the Gp-NBC and was ascribed to the enhancement of graphitic nitrogen. The results from SEM-EDS and XRD, and the zeta potentials for the materials revealed that carbonate precipitation, cation exchange, and electrostatic interactions contributed to the adsorption of Cd(II). XPS and FTIR demonstrated that nitrogen in the carbon framework might have promoted the adsorption by forming cation–π interactions between graphitic nitrogen and Cd(II). The electrostatic potential distribution of the nitrogen with different configurations fully confirmed this. The theoretical calculations also proved that graphitic nitrogen had the lowest interaction energy to Cd(II), which further verified the strong contribution of graphitic nitrogen to the adsorption of heavy metal. Nitrogen-enriched biochar effectively adsorbs, changes the migration process of heavy metals in the natural environment, and thus alleviates the current situation of heavy metal pollution.
研究领域:
环境科学
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材料科学
✓ 已验证
产品关联
DOI
高影响因子
ANALYTICAL CHEMISTRY
·
2015
·
IF 5.636
Anbang Zhu,Baiyang Chen,Liang Zhang,Paul Westerhoff
This study evaluated electrodialysis (ED) for direct, accurate, and precise dissolved organic nitrogen (DON) analysis in water. Unlike conventional methods that calculate DON as the difference between total dissolved nitrogen (TDN) and dissolved inorganic nitrogen (DIN), we designed a compact ED reactor as a pretreatment tool that completely separates DIN from DON in water and then measures DON by equating DON to TDN. The experiments confirmed that the ED pretreatment process can achieve 99% removal of all three major DIN species (i.e., ammonia, nitrite, and nitrate) and an average recovery rate of 88% for an array of model DON compounds of varying characteristics (e.g., urea, amino acids, tripeptide, protein, and humic substances). Variations in nitrogen removal and recovery might be explained by a combined effect of molecular weight, acid dissociation ability (pKa), aromaticity, and ED reactor configurations. For model solutions with DIN/DON ratios varying from 1 to 10 mg-N/mg-N, the relative standard deviations in DON concentrations were considerably lower with ED pretreatment (<10%) than without pretreatment (47%). A survey of seven field samples, including lake water, tap water, and treated wastewater, also demonstrated the benefits of using ED pretreatment as compared with a conventional DON analysis method. Overall, this study provides evidence and mechanistic insight for a new DON detection method that uses ED pretreatment. The ED unit is robust for separating DIN and DON, and thus it may facilitate more frequent detection of DON and ultimately enhances understanding of DON issues in the environmental studies.
研究领域:
环境科学
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分析化学
✓ 已验证
DOI
PubMed
高影响因子
INTERNATIONAL JOURNAL OF ENERGY RESEARCH
·
2022
·Vol. 46
·期 13
·18465-18476
·
IF 4.672
Yang You,Qingqing Hu,Fupeng He,Yongjie Liu,Qingyun Huang,Xuyang Liu,Zhixiong You,Xuewei Lv
Summary Ammonia gas (NH 3 ) is a clean energy, as well as an efficient reduction and nitridation agent. A novel process of reduction and nitridation with NH 3 followed by magnetic separation and low-temperature selective chlorination to deal with vanadium slag has been proposed. Vanadium spinel (V-Fe spinel, FeV 2 O 4 ) is the main V-bearing phase in vanadium slag, and its reduction and nitridation behavior with NH 3 were investigated in this study. Thermodynamic analysis indicated that the reaction was feasible. The experimental results demonstrated that NH 3 gas was an excellent reagent for reduction and nitridation. DFT calculation proved that NH 3 molecule was easier adsorbed on V atom. The phase component of the final product was Fe/Fe 4 N/VN x O y , whose relative mass fractions obtained by Rietveld refinement analysis were 23.5%, 1%, and 75.5%, respectively. The evolution of iron and vanadium was in the order FeV 2 O 4 → Fe 4 N/Fe 6 N 2−3 → Fe 4 N/Fe and FeV 2 O 4 → V 2 O 3 → VN x O y , respectively. VN x O y was a solid solution, whose O content decreased gradually as the temperature and duration time increased, whereas the N content increased correspondingly. The O content can be decreased to less than 0.10 wt.% after reduction and nitridation at 800°C to 850°C for 3 h.
研究领域:
冶金工程
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材料科学
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产品关联
DOI
高影响因子
ACS Applied Materials & Interfaces
·
2019
·
IF 8.456
Pengfei Song,Li Kang,Hao Wang,Rong Guo,Rongmin Wang
The electrocatalytic conversion of nitrogen gas at ambient conditions represents a novel approach for ammonia synthesis to the sustainable society. It is critical to understand the detailed pathways and mechanisms of this promising process to develop a highly efficient catalyst. Herein, the N, P co-doping carbon (NP-C-MOF-5) catalyst was prepared for electrocatalytic N2 reduction in acid electrolytes under ambient temperatures and pressures. Experimental results showed that there are two products including NH3 and N2H4·H2O on the NP-C-MOF-5 cathode at −0.1 V versus RHE with the yield of 1.08 and 5.77 × 10–4 μg h–1 mgcat.–1, respectively. Moreover, an electrocatalytic pathway on NP-C-MOF-5 was investigated by the electrochemical in situ Fourier transform infrared technique. The results confirmed the formation of N2Hy (1 ≤ y ≤ 4) intermediates on NP-C-MOF-5 cathode surfaces, suggesting an associative pathway for the N2 reduction reaction.
研究领域:
材料科学
·
化学工程
·
环境科学
✓ 已验证
DOI
高影响因子
Frontiers of Chemical Science and Engineering
·
2022
·Vol. 17
·期 1
·93-101
·
IF 4.803
Xu Huilin,Peng Xiangfeng,Zheng Jingxuan,Wang Zhao
Defect construction and heteroatom doping are effective strategies for improving photocatalytic activity of carbon nitride (g-C 3 N 4 ). In this work, N defects were successfully prepared via cold plasma. High-energy electrons generated by plasma can produce N defects and embed sulfur atoms into g-C 3 N 4 . The N defects obviously promoted photocatalytic degradation performance that was 7.5 times higher than that of pure g-C 3 N 4 . The concentration of N defects can be tuned by different power and time of plasma. With the increase in N defects, the photocatalytic activity showed a volcanic trend. The g-C 3 N 4 with moderate concentration of N defects exhibited the highest photocatalytic activity. S-doped g-C 3 N 4 exhibited 11.25 times higher photocatalytic activity than pure g-C 3 N 4 . It provided extra active sites for photocatalytic reaction and improved stability of N defects. The N vacancy-enriched and S-doped g-C 3 N 4 are beneficial for widening absorption edge and improving the separation efficiency of electron and holes.
研究领域:
材料科学
·
环境科学
✓ 已验证
DOI
高影响因子
NITRIC OXIDE-BIOLOGY AND CHEMISTRY
·
2024
·
IF 3.2
Yang Zhou,Jiajun Chen,Yunxi Cui,Lingjuan Tang,Peixuan Wu,Peng Yu,Kun Fu,Zhicheng Sun,Yuanyuan Liu
The precise release and characterization of nitroxyl (HNO) gas signaling molecule remain a challenge due to its short lifetime to date. To solve this issue, an azobenzene-based HNO donor (Azo-D1) was proposed as a colorimetric and fluorometric chemosensor for HNO releasing, to release both HNO and an azobenzene fluorescent reporter together. Specifically, the Azo-D1 has an HNO release half-life of ∼68 min under physiological conditions. The characteristic color change from the original orange to the yellow color indicated the decomposition of the donor molecule. In addition, the stoichiometry release of HNO was qualitatively and quantitatively verified through the classical phosphine compound trap. As compared with the donor molecule by itself, the decomposed product demonstrates a maximum fluorescence emission at 424 nm, where the increase of fluorescence intensity by 6.8 times can be applied to infer the real-time concentration of HNO. Moreover, cellular imaging can also be achieved using this Azo-D1 HNO donor through photoexcitation at 405 and 488 nm, where the real-time monitoring of HNO release was achieved without consuming the HNO source. Finally, the Azo-D1 HNO donor would open a new platform in the exploration of the biochemistry and the biology of HNO.
研究领域:
化学
·
生物学
·
医学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
SEPARATION AND PURIFICATION TECHNOLOGY
·
2024
·
IF 8.1
Shuyin Zhang,Jing Zou,Lingxuan Chen,Chunhua Shen,Jian Lu,Jianlin Zhang,Hangyu Cui,Geng Huang,Jun Ma
Although thermal-activated peroxymonosulfate (PMS) system possesses good performance on the removal of organic pollutants, thermal/PMS system exhibited poor capacity to remove ammonia nitrogen (NH 4 + -N). This study demonstrated the huge enhancement on the removal of NH 4 + -N by thermal/PMS system with the commonly coexistent bromide ion (Br - ). The elimination of NH 4 + -N by thermal/PMS/Br - system fitted the pseudo -zero-order kinetics model well, while the corresponding k obs in the presence of 200 μM Br - was 5.76 times greater than that by thermal/PMS system. Bromine (HBrO) was confirmed as the dominant oxidant responsible for removing NH 4 + -N and TN, while the radicals of HO ⋅ , SO 4 ⋅- and Br ⋅ were also generated but made minor contribution to removing NH 4 + -N. HBrO was mostly produced by PMS reacting directly with Br - , while these radicals were produced from the cleavage of the O-O bond in PMS and the reaction between PMS and HBrO under high temperature. Thermal/PMS/Br - system exhibited superior performance on TN removal (up to 90 %) than that by thermal/PMS system (less than 5 %) and Cl - -enhanced system (about 80 %). The main removal product of NH 4 + -N was identified as the environmentally friendly gas of N 2 , although nitrate was also detected. Neutral pH condition was the optical pH for NH 4 + -N removal. Increasing reaction temperature, PMS dosage and Br - concentration were beneficial to accelerating the removal of NH 4 + -N. Cations of Cu 2+ and Fe 3+ , anions of SO 4 2- , CO 3 2 - and NO 3 - , humic acid and the actual water matrix of landfill leachate negligibly influenced the removal of NH 4 + -N, while Cl - exhibited strong enhancement on NH 4 + -N removal. In summary, this study provided an effective method to improve the oxidizing capacity of thermal/PMS system, especially for NH 4 + -N removal in wastewater containing Br - .
研究领域:
环境科学
·
污水处理
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产品关联
DOI
高影响因子
危险品化学品经营许可证（带存储）