RESOURCES CONSERVATION AND RECYCLING
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2021
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IF 10.204
Shun Zhang,Shiyu Miao,Xiaoqiang An,Huachun Lan,Ruiping Liu,Jianfeng Peng,Huijuan Liu,Jiuhui Qu
Many efforts have been made to improve the dewaterability during anaerobically digested sludge (ADS) conditioning. However, the conversion of substances in ADS conditioning, as an important process of sludge treatment and application, has received little attention. This study investigated the transformation process of typical components in sludge such as extracellular polymeric substances (EPS), sulfide, Fe and Mn species. The effects of KMnO 4 dosage and pH change on the ADS conditioning were investigated in detail. The results showed that the sludge particle size and capillary suction time decreased with the increase of KMnO 4 dosage. The water content of sludge cake by vacuum filtration gradually dropped from 84.5% to 78.8% after conditioning with 0–5.0 g KMnO 4 /L sludge. Based on fluorescence excitation-emission matrix, EPS and dissolved organic carbon measurements, the improvement of sludge dewaterability was due to the disruption of EPS and the release of intracellular substances. Interestingly, 11.5% sulphides (S 2− ) in ADS were oxidized into SO 4 2− at KMnO 4 dosage of 3.0 g/L, which can effectively inhibit the release of hazardous H 2 S even the sludge pH changed to 2 in conditioning process. Moreover, about 30 mg/L of PO 4 3− in centrifugate can be completely immobilized by the generated iron, manganese and their binary oxides as a result of the interaction between Fe 2+ and KMnO 4 . These findings provided a new insight to explore the sludge conditioning process and the transformation of typical components.
研究领域:
环境科学
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污水处理
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产品关联
DOI
高影响因子
CHEMICAL ENGINEERING JOURNAL
·
2024
·
IF 13.3
Mingwei Zhang,Cheng-Bin Hong,Zhaoying Ding,Yujing Weng,Honghui Gong,Haiyong Wang,Yulong Zhang,Yuhe Liao,Haichao Liu
Hydrogenolysis of glycerol is an important reaction in biomass valorization, and requires efficient catalysts for selectively removing its hydroxyl groups to yield valuable chemicals, such as 1-propanol and 1,2-propanediol. In this work, we synthesized a porous and non-stoichiometric tungsten oxide (WO x ) by a solvothermal method, and a serious of WO x -supported Pt and Mn ((Mn)Pt/WO x ) catalysts by reduction with H 2 at different temperatures. On these catalysts, the product selectivity in the glycerol hydrogenolysis was significantly influenced by the presence of the Mn species and reduction temperatures. The catalysts after reduction with H 2 at lower temperatures favored the formation of 1-propanol, affording a yield of 88.0 % at 240 °C, while those reduced at higher temperatures facilitated the formation of 1,2-propanediol in a yield of 93.0 % under the same reaction conditions. Extensive analysis of these catalysts by in-situ and ex-situ characterizations showed that the high-temperature reduction led to the formation of MnWO 4 on the Mn/Pt/WO x catalysts and the consequent decrease in the acidic sites and increase in the basic sites, facilitating the alkali-assisted dehydrogenation of glycerol and selective formation of 1,2-propanediol. This study provides fundamental insights into the role of the W and Mn species in tuning the selectivity of the glycerol hydrogenolysis, which will be valuable for designing catalysts towards the valorization of other biomass-based feedstocks.
研究领域:
催化化学
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生物质转化
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材料科学
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产品关联
DOI
高影响因子
APPLIED SURFACE SCIENCE
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2017
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IF 3.387
Jun Li,Jia Fang,Long Gao,Jingwen Zhang,Xinchao Ruan,Aihua Xu,Xiaoxia Li
Low valent manganese species and surface oxygen vacancies in OMS-2 play an important role in catalytic reactions, and it is highly desirable and challenging to develop a feasible strategy of increasing the Mn(II) and Mn(III) species concentration in the oxide. Herein, the OMS-2/g-C 3 N 4 hybrids (OMS-2/CN) were prepared by a facile refluxing approach. It was found that the MnO x precursor from the reaction of KMnO 4 and MnSO 4 was transformed into OMS-2 nanofibers with the formation of more Mn(II) and Mn(III) species in OMS-2 and the destruction and oxidation of g-C 3 N 4. The hybrids exhibited higher efficiency for pollutants degradation in the presence of PMS than the pure OMS-2 or g-C 3 N 4 . There was a linear correlation between the specific initial rate and the ratio of Mn(II + III)/Mn(IV). Mechanism investigation indicated that high active manganese species or caged radicals were produced through the oxidation of Mn(II) and Mn(III) by PMS and contributed to the degradation reaction. During five consecutive cycles, the catalyst exhibited good reusability and stability. Therefore, the OMS-2/CN hybrids are promising catalysts for wastewater treatment with PMS as the oxidant.
研究领域:
环境科学
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催化化学
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产品关联
DOI
高影响因子
ENVIRONMENTAL RESEARCH
·
2024
·
IF 7.7
Mei An,Xiaoxiang Cheng,Xinsheng Luo,Tao Yang,Xianpeng Sun,Jingtao Xu,Dao Xiao,Daoji Wu,Heng Liang
Ultrafiltration (UF) is a highly efficient technique for algal-rich water purification, but it is heavily contaminated due to the complex water characteristics. To solve this problem, potassium permanganate (KMnO 4 ) oxidation enhanced with sodium sulfite (Na 2 SO 3 ) was proposed as a pretreatment means. The results showed that the end-normalized flux was elevated from 0.10 to 0.91, and the reversible fouling resistance was reduced by 99.95%. The membrane fouling mechanism also changed obviously, without the generation of cake filtration. Regarding the properties of algal-rich water, the zeta potential was decreased from −29.50 to −5.87 mV after KMnO 4 /Na 2 SO 3 pretreatment, suggesting that the electrostatic repulsion was significantly reduced. Meanwhile, the fluorescent components in algal-rich water were significantly eliminated, and the removal of dissolved organic carbon was increased to 67.46%. In the KMnO 4 /Na 2 SO 3 process, reactive manganese species (i.e., Mn(V), Mn(III) and MnO 2 ) and reactive oxygen species (i.e., SO 4 •− and • OH) played major roles in purifying algal-rich water. Specifically, SO 4 •− , • OH, Mn(V) and Mn(III) could effectively oxidize algal pollutants. Simultaneously, the in-situ adsorption and coagulation of MnO 2 could accelerate the formation of flocs by decreasing the electrostatic repulsion between cells, and protect the algal cells from being excessive oxidized. Overall, the KMnO 4 /Na 2 SO 3 process showed significant potential for membrane fouling alleviation in purifying algal-rich water.
研究领域:
环境科学
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水处理工程
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产品关联
DOI
PubMed
高影响因子
WATER RESEARCH
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2021
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IF 11.236
Yuan Gao,Yang Zhou,Su-Yan Pang,Jin Jiang,Yong-Ming Shen,Yang Song,Jie-Bin Duan,Qin Guo
In recent years, the activation of persulfates (peroxydisulfate (PDS) and peroxymonosulfate (PMS)) via transition metal ions for contaminants degradation has received extensive attention in water treatment. There has been growing interest on the mechanism (radical versus non-radical pathway) of activation processes. Interestingly, in contrast to copper, iron or cobalt ions regarded as effective activators for persulfates, manganese ion (Mn(II)) is inefficient for persulfates activation. Inspired by the enhanced stability of manganese species by ligands, this study for the first time systematically investigated the Mn(II)/persulfates with different ligands as a novel oxidation technology. UV-vis spectrometry, chemical probing method and mass spectrometry were used to explore the reactive intermediate (free radical versus high-valent manganese species) therein. It was surprisingly found that the oxidation efficiency of Mn(II)/ligand/persulfates system was highly dependent on the nature of persulfates and ligands. Mn(II) chelated by amino ligands such as ethylenediaminetetraacetic acid (EDTA) and nitrilotriacetate (NTA) could efficiently trigger the oxidation of contaminants (e.g., recalcitrant compounds nitrophenol, benzoic acid and atrazine) by PMS , suggesting a promising Mn(II)/ligand/PMS technology for environmental decontamination especially under manganese-rich conditions. High-valent Mn species (Mn(V)) but not free radicals was demonstrated to be the dominant reactive intermediate, where Mn(III) species played a vital role in Mn(V) generation. The formation of Mn(III) species was found to be affected by the reactivity of persulfates and the type of ligands, thus influencing its further oxidation to Mn(V) species. This study presents a new oxidation process based on the combination of PMS and Mn(II) complex and broadens the knowledge of persulfates activation as well as manganese chemistry for decontamination in water treatment.
研究领域:
环境科学
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水处理技术
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产品关联
DOI
PubMed
高影响因子
Journal of Environmental Chemical Engineering
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2025
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IF 7.2
Qin Guo,Ying Cao,Jin Jiang,Juan Li
The permanganate/sulfite (Mn(VII)/sulfite) process has shown promise for degrading recalcitrant organic micropollutants, yet current methods to differentiate the roles of intermediate manganese species (IMS) and sulfate radicals (SO₄ •- ) show limitations. In this study, atrazine (ATZ) - a widely detected and oxidation-resistant herbicide - was used as a probe compound to investigate the reactivity of IMS and SO₄ •- generated in the Mn(VII)/sulfite system. ATZ exhibited negligible degradation by Mn(VII) alone but underwent rapid transformation within seconds in the presence of sulfite, with degradation efficiency increasing at lower pH and optimal [Mn(VII)]/[sulfite] ratios. Using stopped-flow spectrophotometry, pseudo-first-order kinetics were confirmed. Six major transformation products were identified, among which atrazine amide (CDIT) and desethyl-atrazine (DEA) were predominant. The molar ratio of CDIT to DEA ([CDIT]/[DEA]) was evaluated as a mechanistic indicator. A consistent ratio of ~4.8 at low sulfite levels indicated Mn(V)-dominated oxidation, while lower ratios at higher sulfite concentrations reflected increasing contributions from Mn(III) and SO 4 •− . This trend was supported across pH 3, 5, and 7. Water matrix components such as natural organic matter and nitrite were found to inhibit ATZ degradation, likely due to their scavenging of reactive species. This study establishes the [CDIT]/[DEA] ratio as a novel mechanistic indicator in manganese-activated oxidation and highlights the Mn(VII)/sulfite process as an effective strategy for degrading recalcitrant micropollutants in water treatment.
研究领域:
环境化学
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水处理技术
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氧化还原过程
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污染物降解机制
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自由基化学
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产品关联
DOI
高影响因子
Reaction Chemistry & Engineering
·
2022
·Vol. 7
·期 12
·2611-2617
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IF 5.2
Long Deng,Yiran Jiao,Yuan Pu,Dong Liu,Dan Wang
Synthesis of pyridinic nitrogen-rich polymers is a key step in obtaining high-performance polypyrrole-derived electrocatalysts for the oxygen reduction reaction. A straightforward and controllable synthesis method is highly favored to efficiently manipulate the structural and electronic properties of polypyrrole-derived electrocatalysts. Herein, the strategy for the preparation of poly(2,6-diaminopyridine) (PDAP) is developed with the assistance of an external circulation rotating packed bed (EC-RPB). The polymerization could be divided into two stages: a kinetically fast stage and a rate-determining phase-transfer stage. By using the EC-RPB, the polymerization is sufficiently reduced to 3 h with a conversion rate of over 90% achieved due to accelerated mass transfer in the second stage, exhibiting significant improvement in the common processing for PDAP (∼87% in 12 h). Furthermore, with co-doped iron and manganese species, the obtained catalyst shows a good ORR activity and stability, with up to 0.881 V of half-wave potential in an alkaline environment and 0.718 V in an acid environment. This work proposes a facile and efficient synthesis method for PDAP which could also be extended to the production of other polypyridine-derived electrocatalysts.
研究领域:
材料科学
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电化学
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催化
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产品关联
DOI
高影响因子
Desalination and Water Treatment
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2024
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IF 1
Hongbo Fang,Liqian Dai,Shuyan Wang,Weiye Shi,Defang Ma
The permanganate/bisulfite (PM/BS) process is highly efficient in the oxidation of refractory contaminants due to the generation of a large number of reactive manganese species and radicals. However, a lot of concerns need to be addressed for the application of the PM/BS process in real sulfamerazine (SMZ) contaminated water treatment. The factors affecting the degradation efficiency of SMZ by PM/BS and the influences of PM/BS pre-oxidation on the formation and toxicity of trihalomethanes (THMs) during the subsequent chlorination of simulated SMZ-contaminated waters were investigated in this study. The PM/BS process exhibited fast oxidation of SMZ at acidic/neutral pH and low SMZ concentration (5 μm) with more than 80% of SMZ removal within 15 s. The permanganate was efficiently activated by bisulfite and exhibited high efficiency in SMZ degradation when permanganate/bisulfite dosage was 50 μm:250 μm. The co-existing protein bovine serum albumin caused less than 10% inhibition of SMZ degradation in the PM/BS process at pH 6 and 7. However, humic acids and alginate inhibited the removal of SMZ by 18%–57%. PM/BS pre-oxidation of SMZ-contaminated waters achieved a 28%–64% reduction of THM formation in the subsequent chlorination, greatly decreasing the toxicity risk in chlorination.
研究领域:
环境科学
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水处理技术
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化学氧化
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高级氧化工艺
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毒理学
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DOI
高影响因子
危险品化学品经营许可证（带存储）