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Hemin-histamine-montmorillonite clay conjugate as a model biocatalyst to mimic natural peroxidase

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Science China Chemistry 2015年第4期58卷 731-737页

作者： Lihui Zhang Cheng Gu Jian Xiong Mei Yang Yong Guo state key laboratory of pollution control & Resource Reuse School of the Environment Nanjing University

We successfully synthesized the first hemin-montmorillonite bio-conjugate with an amino acid residue to mimic natural peroxidase enzyme. Histamine was intercalated in montmorillonite by cation exchange, then a heroin molecule was loaded onto the histamine-montmorillonite with an adsorption capacity of 7.0 mg· g^-1. The hemin-histamine-montmorillonite conjugate shows high peroxidase activity as indicated by the oxidation of guaiacol, which is attributed to the activation of hemin by Fe-N complex formation between the imidazole group in histamine and the iron ion in the hemin molecule. Temperaturedependent peroxidase activity for this synthesized biomimetic material indicates that raising the reaction temperature could significantly enhance the activity of the conjugate. The biomimetic catalyst has good reusability; nearly 100% activity can be retained after three cycles. Because montmorillonite clay is widely distributed in the environment, this material offers great potential for in situ and ex situ remediation of many organic contaminants in surface/subsurface soils.

关键词： hemin-histamine-montmorillonite conjugates imidazole biomimetic catalyst peroxidase activity recycle

Inhibition effect of magnetic field on nitrous oxide emission from sequencing batch reactor treating domestic wastewater at low temperature

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Journal of environmental Sciences 2020年第1期32卷 205-212页

作者： Dan Xu Hongmin Ji Hongqiang Ren Jinju Geng Kan Li Ke Xu state key laboratory of pollution control and Resource Reuse School of the EnvironmentNanjing University

This study aims to investigate the effect of a magnetic field on nitrous oxide(N2O)emission from a sequencing batch reactor treating low-strength domestic wastewater at low temperature(10℃).After running for 124 days in parallel,results indicated that the conversion rate of N2O for a magnetic field-sequencing batch reactor(MF-SBR)decreased by34.3%compared to that of a conventional SBR(C-SBR).Meanwhile,the removal efficiencies for total nitrogen(TN)and ammonia nitrogen(NH4-N)of the MF-SBR were 22.4%and 39.5%higher than those of the ***-throughput sequencing revealed that the abundances of AOB(Nitrosomonas),NOB(Nitrospira)and denitrifiers(Zoogloea),which could reduce N2O to N2,were promoted significantly in the *** activities(Nir)and gene abundances(nos Z nir S and nir K)for denitrification in the MF-SBR were also notably higher compared to *** study shows that application of a magnetic field is a useful approach for inhibiting the generation of N2O and promoting the nitrogen removal efficiency by affecting the microbial characteristics of sludge in an SBR treating domestic wastewater at low temperature.

关键词： Magnetic field Low temperature N2O emission Biological nitrogen removal High-throughput 16S rRNA gene sequencing

Ligand effects on arsenite removal by zero-valent iron/O2: Dissolution, corrosion, oxidation and coprecipitation

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Journal of environmental Sciences 2019年第12期31卷 131-140页

作者： Xiaojie Song Chen Zhang Bingdang Wu Xiaomeng Wang Zhihao Chen Shujuan Zhang state key laboratory of pollution control and Resource Reuse School of the Environment Nanjing University

Ligands may increase the yields of reactive oxygen species(ROS)in zero-valent iron(ZVI)/O2 *** clarify the relationship between the properties of ligands and their effects on the oxidative removal of contaminants,five common ligands(formate,acetate,oxalate,ethylenediaminetetraacetic acid(EDTA),and phosphate)as well as acetylacetone(AA)were investigated with arsenite(As(III))as the target contaminant at three initial p H values(3.0,5.0,and 7.0).The addition of these ligands to the ZVI/O2 system resulted in quite different effects on As(III)*** enhanced the oxidation of As(III)to arsenate(As(V))but inhibited the removal of As(V).Oxalate was the only ligand in this work that accelerated both the removal of As(III)and As(V).By analyzing the ligand effects from the four aspects:dissolution of surface iron(hydr)oxides,corrosion of ZVI,reaction with ROS,and interference with precipitation,the following properties of ligands were believed to be important:ability to provide dissociable protons,complexation ability with iron,and reactivity with *** complexation ability is a double-edged *** could enhance the generation of ROS by reducing the reduction potential of the Fe(III)/Fe(II)redox couple,but also could inhibit the removal of arsenic by *** elucidated relationship between the key property parameters of ligands and their effects on the ZVI/O2 system is helpful for the rational design of effective ZVI/ligand/O2 systems.

关键词： Zero-valent iron Ligand Arsenite Acetylacetone

Application potential of carbon nanotubes in water treatment:A review

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Journal of environmental Sciences 2013年第7期25卷 1263-1280页

作者： Xitong Liu Mengshu Wang Shujuan Zhang Bingcai Pan state key laboratory of pollution control and Resource Reuse School of the EnvironmentNanjing University

Water treatment is the key to coping with the conflict between people＇s increasing demand for water and the world-wide water shortage. Owing to their unique and tunable structural, physical, and chemical properties, carbon nanotubes （CNTs） have exhibited great potentials in water treatment. This review makes an attempt to provide an overview of potential solutions to various environmental challenges by using CNTs as adsorbents, catalysts or catalyst support, membranes, and electrodes. The merits of incorporating CNT to conventional water-treatment material are emphasized, and the remaining challenges are discussed.

关键词： carbon nanotube adsorption catalysis membrane water treatment

Synthesis, crystal structure, photodegradation kinetics and photocatalytic activity of novel photocatalyst ZnBiYO_4

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Journal of environmental Sciences 2015年第3期27卷 51-61页

作者： Yanbing Cui Jingfei Luan state key laboratory of pollution control and Resource Reuse School of the Environment Nanjing University

ZnBiYO4 was synthesized by a solid-state reaction method for the first time. The structural and photocatalytic properties of ZnBiYO4 were characterized by X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy and UV-Vis diffuse reflectance. ZnBiYO4 crystallized with a tetragonal spinel structure with space group I41/A. The lattice parameters for ZnBiYO4 were a = b = 11.176479 A and c = 10.014323 A. The band gap of ZnBiYO4 was estimated to be 1.58 eV. The photocatalytic activity of ZnBiYO4 was assessed by photodegradation of methyl orange under visible light irradiation. The results showed that ZnBiY04 had higher catalytic activity compared with N-doped TiO2 under the same experimental conditions using visible light irradiation. The photocatalytic degradation of methyl orange with ZnBiYO4 or N-doped TiO2 as catalyst followed first-order reaction kinetics, and the first-order rate constant was 0.01575 and 0.00416 rain-1 for ZnBiYO4 and N-doped TiO2, respectively. After visible hght irradiation for 220 min with ZnBiYO4 as catalyst, complete removal and mineralization of methyl orange were observed. The reduction of total organic carbon, formation of inorganic products, SO24- and NO3^-, and evolution of CO2 revealed the continuous mineralization of methyl orange during the photocatalytic process. The intermediate products were identified using liquid chromatog- raphy-mass spectrometry. The ZnBiYO4/（visible light） photocatalysis system was found to be suitable for textile industry wastewater treatment and could be used to solve other environmental chemical pollution problems.

关键词： ZnBiYO4 and N-doped TiO2Methyl orangeVisible light irradiationPhotodegradation pathwayStructural properties

Application of a green coagulant with PACl in efficient purification of turbid water and its mechanism study

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Journal of environmental Sciences 2019年第7期31卷 168-180页

作者： Yuxiang Xue Zhouzhou Liu Aimin Li Hu Yang state key laboratory of pollution control and Resource Reuse School of the Environment Nanjing University

The applications of natural polymeric flocculants due to their green feature has been recently received much more attention. In this work, the combined usages of a cationic starch-based coagulant and polyaluminum chloride(PACl) were extensively evaluated for various addition sequences in the coagulation of both raw(surface water from the Jiuxiang River) and synthetic turbid water(two kaolin suspensions with different initial turbidities).Two typical cationic starch-based coagulants with different structures(St-G and St-E) were tried. In comparison to St-G, St-E and PACl used individually as well as St-G and St-E dosed after PACl, the combination of the starch-based coagulants fed before PACl showed higher turbidity removal efficiency, which featured not only less optimal doses of both inorganic and organic coagulants but also lower residual turbidity. On the basis of a detailed analysis of the particle size and its distribution in solution supernatants before and after coagulation by two starch-based coagulants and PACl, polymeric coagulants preferentially coagulate the small-sized colloids due to their distinct long-chain structures, but PACl preferentially coagulates the medium-sized ones. Thus, the medium-sized particles that were previously formed by the starch-based coagulants would be collectively and effectively removed by the subsequent addition of PACl. The addition sequence of the inorganic and organic coagulants in their combined usage is an important factor for improvement of the turbidity removal efficiency in practice.

关键词： Cationic starch-based green coagulants Polyaluminum chloride Combined coagulation Synergistic coagulation effects Synergistic mechanisms

Potential bioavailability of mercury in humus-coated clay minerals

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Journal of environmental Sciences 2015年第10期27卷 48-55页

作者： Daiwen Zhu Huan Zhong Nanjing University School of EnvironmentState Key Laboratory of Pollution Control and Resource Reuse

It is well-known that both clay and organic matter in soils play a key role in mercury biogeochemistry, while their combined effect is less studied. In this study, kaolinite,vermiculite, and montmorillonite were coated or not with humus, and spiked with inorganic mercury（IHg） or methylmercury（Me Hg）. The potential bioavailability of mercury to plants or deposit-feeders was assessed by CaCl2 or bovine serum albumin（BSA） extraction. For uncoated clay, IHg or Me Hg extraction was generally lower in montmorillonite, due to its greater number of functional groups. Humus coating increased partitioning of IHg（0.5%–13.7%） and Me Hg（0.8%–52.9%） in clay, because clay-sorbed humus provided more strong binding sites for mercury. Furthermore, humus coating led to a decrease in IHg（3.0%–59.8% for CaCl2 and 2.1%–5.0% for BSA） and Me Hg（8.9%–74.6% for CaCl2 and 0.5%–8.2% for BSA）extraction, due to strong binding between mercury and clay-sorbed humus. Among various humus-coated clay particles, mercury extraction by CaCl2（mainly through cation exchange）was lowest in humus-coated vermiculite, explained by the strong binding between humus and vermiculite. The inhibitory effect of humus on mercury bioavailability was also evidenced by the negative relationship between mercury extraction by CaCl2 and mercury in the organo-complexed fraction. In contrast, extraction of mercury by BSA（principally through complexation） was lowest in humus-coated montmorillonite. This was because BSA itself could be extensively sorbed onto montmorillonite. Results suggested that humus-coated clay could substantially decrease the potential bioavailability of mercury in soils, which should be considered when assessing risk in mercury-contaminated soils.

关键词： Methylmercury Chemical extraction Soil Sequential extraction

Improved performance and prolonged lifetime of titania-based materials: sequential use as adsorbent and photocatalyst

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Science China Chemistry 2015年第7期58卷 1211-1219页

作者： Yan Peng Minghui Li Shujuan Zhang Guangze Nie Meng Qi Bingcai Pan state key laboratory of pollution control and Resource Reuse School of the environment Nanjing University

Lifetime is a key index in the evaluation of environmentally functional materials. Although it is well known that adsorption is the first step in photocatalysis, very little work has been done on the sequential use of materials as both adsorbents and photo- catalysts. In this work, two titania-based materials, TiO2 xerogel and TiO2 photocatalyst nanoparticles, were fabricated and evaluated as adsorbent and photocatalyst for the remediation of contaminated water with an azo dye, Acid Orange 7 （AO7）, as the modeling pollutant. The TiO2 xerogel showed a high adsorption capacity to AO7 （769 mg/g） and could be regenerated eas- ily with diluted NaOH solution （0.01 mol/L） for several cycles. The exhausted xerogel was calcined at 400 ℃ for 3 h and used as a photocatalyst for the degradation of AO7. Compared to the nanoparticles directly prepared from fresh TiO2 xerogel, the TiO2 nanoparticles from adsorption exhausted xerogel showed a much higher photocatalytic activity upon both UV and visible light irradiation. Thus the titania-based materials were endowed with improved performance as well as prolonged lifetime.

关键词： titanium dioxide adsorbent reuse photocatalyst azo dye

Year-round changes in tropospheric nitrogen dioxide caused by COVID-19 in China using satellite observation

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Journal of environmental Sciences 2023年第10期132卷 162-168页

作者： Zhenyu Luo Hailian Xu Zhining Zhang Songxin Zheng Huan Liu state key joint laboratory of ESPC State Environmental Protection Key Laboratory of Sources and Control of Air Pollution ComplexSchool of EnvironmentTsinghua UniversityBeijing 100084China

The lockdown policy deals a severe blow to the economy and greatly reduces the nitrogen oxides(NOx)emission in China when the coronavirus 2019 spreads widely in early *** we use satellite observations from Tropospheric Monitoring Instrument to study the year-round variation of the nitrogen dioxide(NO_(2))tropospheric vertical column density(TVCD)in *** NO_(2)TVCD reveals a sharp drop,followed by small fluctuations and then a strong rebound when compared to *** the end of 2020,the annual average NO_(2)TVCD declines by only 3.4%in Chinamainland,much less than the reduction of 24.1%in the lockdown *** the basis of quantitative analysis,we find the rebound of NO_(2)TVCD is mainly caused by the rapid recovery of economy especially in the fourth quarter,when contribution of industry and power plant on NO_(2)TVCD continues to *** revenge bounce of NO_(2)indicates the emission reduction of NOx in lockdown period is basically offset by the recovery of economy,revealing the fact that China’s economic development and NOx emissions are still not *** efforts are still required to stimulate low-pollution development.

关键词： COVID-19 Tropospheric NO2 TROPOMI Economy recovery environment sustainability