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A settling curve modeling method for quantitative description of the dispersion stability of carbon nanotubes in aquatic environments

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Journal of Environmental Sciences 2015年第3期27卷 1-10页

作者： Lixia Zhou Dunxue Zhu Shujuan Zhang bingcai pan State Key Laboratory of Pollution Control and Resource Reuse School of the Environment Nanjing University

Understanding the aggregation and deposition behavior of carbon nanotubes （CNTs） is of great significance in terms of their fate and transport in the environment. Attachment efficiency is a widely used index for well-dispersed CNT solutions. However, in natural waters, CNTs are usually heterogeneous in particle size. The attachment efficiency method is not applicable to such systems. Describing the dispersion stability of CNTs in natural aquatic systems is still a challenge. In this work, a settling curve modeling （SCM） method was developed for the description of the aggregation and deposition behavior of CNTs in aqueous solutions. The effects of water chemistry （natural organic matter, pH, and ionic strength） on the aggregation and deposition behavior of pristine and surface-functionalized multi-walled carbon nanotubes （MWCNTs） were systematically studied to evaluate the reliability of the SCM method. The results showed that, as compared to particle size and optical density, the centrifugal sedimentation rate constant （ks） from the settling curve profile is a practical, useful and reliable index for the description of heterogeneous CNT suspensions. The SCM method was successfully applied to MWCNT in three natural waters. The constituents in water, especially organic matter, determine the dispersion stability of MWCNTs in natural water bodies.

关键词： Settling curveCarbon nanotubesHeterogeneousCentrifugal sedimentationrate constant

Surface chemistry of polymer-supported nano-hydrated ferric oxide for arsenic removal: effect of host pore structure

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Science China Chemistry 2015年第4期58卷 722-730页

作者： Guangze Nie Jing Wang bingcai pan Lu Lv State Key Laboratory of Pollution Control and Resource Reuse School of the Environment Nanjing University

Immobilization of hydrous ferric oxide(HFO) particles inside solid hosts of porous structure is an important approach to improve their applicability in advanced water treatment such as arsenic and heavy metal removal. Here, we fabricated three polystyrene(PS)-based nano-HFOs and explored the effect of host pore structure on the surface chemistry of the immobilized HFOs. Potentiometric titration of the hybrids and surface complexation modeling of their adsorption towards arsenite and arsenate were performed to evaluate the surface chemistry variation of the loaded HFOs. Polymer hosts of higher surface area and narrower pore size would result in smaller particle size of HFOs and lower the value of the point of zero charge. Also, the site density(normalized by Fe mass) and the deprotonation constants of the loaded HFOs increased with the decreasing host pore size. Arsenite adsorption did not change the surface charge of the loaded HFOs, whereas arsenate adsorption accompanied more of the negative surface charges. Adsorption affinity of both arsenic species with three HFO hybrids were compared in terms of the intrinsic surface complexation constants optimized based on the adsorption edges. HFO loaded in polystyrene host of smaller pore size exhibits stronger affinity with arsenic species.

关键词： hydrated ferric oxide arsenic adsorption nanocomposite surface chemistry

Weakly hydrophobic nanoconfinement by graphene aerogels greatly enhances the reactivity and ambient stability of reactivity of MIL-101-Fe in Fenton-like reaction

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Nano Research 2021年第7期14卷 2383-2389页

作者： Yuwei Zhang Fei Liu Zhichao Yang Jieshu Qian bingcai pan Jiangsu Key Laboratory of Chemical Pollution Control and Resources Reuse School of Environmental and Biological EngineeringNanjing University of Science and TechnologyNanjing 210094China State Key Laboratory of Pollution Control and Resource Reuse School of the EnvironmentNanjing UniversityNanjing 210023China Research Center for Environmental Nanotechnology(ReCENT) Nanjing UniversityNanjing 210023China

In the pursuit of heterogeneous catalysts with high reactivity,metal organic framework(MOF)nanomaterials have received tremendous ***,many MOF catalysts especially Fe-based MOFs need to be utilized immediately after synthesis or being activated using high temperature,because of the easy loss of reactivity in humid environments resulting from the occupation of active Fe sites by water ***,we describe an inspiring strategy of growing MIL-101-Fe nanoparticles inside the three-dimensional confined space of graphene aerogel(GA),generating shapeable GA/MIL-101-Fe nanocomposite convenient for practical *** to MIL-101-Fe,GA/MIL-101-Fe as catalyst demonstrates much higher reactivity in Fenton-like reaction,attributing to smaller MIL-101-Fe particle size,presence of active Fe(II)sites,and abundant defects in ***,the weakly hydrophobic nature of the composite greatly inhibits the loss of catalytic reactivity after being stored in humid air and accelerates the recovery of reactivity in mild temperature,by resisting the entrance of water molecules and helping to exclude water *** work demonstrates that a delicate design of nanocomposite structure could not only improve the reactivity of the catalytic component,but also overcome its intrinsic drawback by taking advantage of the properties of *** hope this functional nanoconfinement strategy could be extended to more scenarios in other fields.

关键词： nanoconfinement hydrophobicity MIL-101-Fe graphene aerogel Fenton-like reaction

Validation of polymer-based nano-iron oxide in further phosphorus removal from bioeffluent： laboratory and scaled- up study

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Frontiers of Environmental Science & Engineering 2013年第3期7卷 435-441页

作者： Ming HUA Lili XIAO bingcai pan Quanxing ZHANG State Key Laboratory of Pollution Control and Resource Reuse School of the Environment Xianlin Campus Nanjing University Nanjing 210023 China

The efficient removal of phosphorous from water is an important but challenging task. In this study, we validated the applicability of a new commercially available nanocomposite adsorbent, i.e., a polymer-based hydrated ferric oxide nanocomposite （HFO-201）, for the further removal of phosphorous from the bioefftuent discharged from a municipal wastewater treatment plant, and the operating parameters such as the flow rate, temperature and composition of the regenerants were optimized. Labora- tory-scale results indicate that phosphorous in real bioeffluent can be effectively removed from 0.92 mg· L^-1 to 〈 0.5 mg· L^-1 （or even 〈 0.1 mg·L^-1 as desired） by the new adsorbent at a flow rate of 50 bed volume （BV） per hour and treatable volume of 3500-4000BV per run. Phosphorous removal is independent of the ambient temperature in the range of 15℃-40℃. Moreover, the exhausted HFO-201 can be regenerated by a 2% NaOH ＋ 5% NaC1 binary solution for repeated use without significant capacity loss. A scaled-up study further indicated that even though the initial total phosphorus （TP） was as high as 2 mg·L^-1, it could be reduced to 〈 0.5 mg·L^-1, with a working capacity of 4.4-4.8 g·L^-1 HFO- 201. In general, HFO-201 adsorption is a choice method for the efficient removal of phosphate from biotreated waste effluent.

关键词： bioeffluent phosphorus removal nanocom-posite adsorbent hydrated ferric oxide

Solid Bronsted acidity boosts adsorption reactivity of nano-adsorbent for water decontamination

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Frontiers of Environmental Science & Engineering 2024年第7期18卷 23-34页

作者： Sikai Cheng Zhixian Li Kaisheng Zhang Qingrui Zhang Xiaolin Zhang bingcai pan State Key Laboratory of Pollution Control and Resource Reuse School of the EnvironmentNanjing UniversityNanjing 210023China Environmental Materials and Pollution Control Laboratory Institute of Solid State PhysicsHFIPSChinese Academy of SciencesHefei 230031China State Key Laboratory of Metastable Materials Science and Technology Yanshan UniversityQinhuangdao 066004China Hebei Key Laboratory of Heavy Metal Deep-remediation in Water and Resource Reused Qinhuangdao 066004China Research Center for Environmental Nanotechnology(ReCENT) Nanjing UniversityNanjing 210023China

Despite the development of various Lewis acidic nano-adsorbents for fluoride removal through innersphere coordination,strong competition for hydroxyl ions still hinders efficient water *** addition,the critical issue of polysilicate scaling that results from the ubiquitous silicates must be *** tackle these issues,an alternative approach to enhancing adsorption reactivity by modifying nano-adsorbents with dual Lewis and Bronsted acidity is *** feasibility of this approach is demonstrated by growing zirconium phosphate(ZrP)inside a gel-type anion exchanger,N201,to produce nanocomposite ZrP@N201,in which the confined ZrP contained an otherwise metastable amorphous phase with Lewis acidic Zr^(4+) sites and Bronsted acidic monohydrogen phosphate groups(-O_(3)POH).Compared with the Lewis acidic nano-zirconium oxide analog(HZ0@N201),ZrP@N201 exhibited a greatly improved adsorption capacity(117.9 vs.52.3 mg/g-Zr)and mass transfer rate(3.56×10^(-6) vs.4.55×10^(-7) cm/s),while bulk ZrP produced a thermodynamically stableα-phase with Bronsted acidity that exhibited negligible adsorption capability toward *** enhanced defluoridation activity of ZrP@N201 is attributed to Bronsted acidity and the increased outer electron density of ZA+sites,as corroborated using XPS and solid-state NMR ***,Bronsted acidity strengthens the resistance of ZrP@N201 to silicate,allowing its full regeneration during cyclic *** tests demonstrated 3-10 times the amount of clean water from(waste)for ZrP@N201 as compared to both HZO@N201 and the widely used activated aluminum *** study highlights the potential of developing nano-adsorbents with dual acidities for various environmental remediation applications.

关键词： Nanocomposite Selective adsorption Fluoride removal Dual Lewis and Bronsted acidity Regeneration

Enhanced debromination of 4-bromophenol by the UV/sulfite process：Efficiency and mechanism

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Journal of Environmental Sciences 2017年第4期29卷 231-238页

作者： Bihuang Xie Xuchun Li Xianfeng Huang Zhe Xu Weiming Zhang bingcai pan State Key Laboratory of Pollution Control and Resource Reuse School of the EnvironmentNanjing University

Halogenated aromatic compounds have attracted increasing concerns due to their toxicity and persistency in the environment, and dehalogenation is one of the promising treatment and detoxification methods. Herein, we systematically studied the debromination efficiency and mechanism of para-bromophenol（4-BP） by a recently developed UV/sulfite process. 4-BP underwent rapid degradation with the kinetics accelerated with the increasing sulfite concentration, pH（6.1–10） and temperature, whereas inhibited by dissolved oxygen and organic solvents. The apparent activation energy was estimated to be 27.8 kJ/mol. The degradation mechanism and pathways of 4-BP were explored by employing N2O and nitrate as the electron scavengers and liquid chromatography/mass spectrometry to identify the intermediates. 4-BP degradation proceeded via at least two pathways including direct photolysis and hydrated electron-induced debromination. The contributions of both pathways were distinguished by quantifying the quantum yields of 4-BP via direct photolysis and hydrated electron production in the system. 4-BP could be readily completely debrominated with all the substituted Br released as Br-, and the degradation pathways were also proposed. This study would shed new light on the efficient dehalogenation of brominated aromatics by using the UV/sulfite process.

关键词： Debromination Brominated aromatics UV/sulfite process Hydrated electron Mechanism

Enhanced methane production during long-term UASB operation at high organic loads as enabled by the immobilized Fungi

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Frontiers of Environmental Science & Engineering 2022年第6期16卷 47-59页

作者： Qiong Guo Zhichao Yang Bingliang Zhang Ming Hua Changhong Liu bingcai pan State Key Laboratory of Pollution Control and Resource Reuse School of EnvironmentNanjing UniversityNanjing 210023China Research Center for Environmental Nanotechnology(ReCENT) Nanjing UniversityNanjing 210023China School of Life Sciences Nanjing UniversityState Key Laboratory of Pharmaceutical BiotechnologyNanjing 210023China

Anaerobic digestion is widely applied in organic wastewater treatment coupled with bioenergy production,and how to stabilize its work at the high organic loading rate(OLR)remains a ***,we proposed a new strategy to address this issue via involving the synergetic role of the Aspergillus sydowii 8L-9-F02 immobilized beads(AEBs).A long-term(210-day)continuous-mode operation indicated that the upflow anaerobic sludge bed(UASB)reactor(R1,with AEBs added)could achieve the OLR as high as 25.0 kg/(m^(3)×d),whereas the control reactor(R0,with AEBs free)could only tolerate the maximum OLR of 13.3 kg/(m^(3)×d).Remarkably,much higher COD removal(85.9%vs 23.9%)and methane production(5.4 m^(3)/(m^(3)×d)vs 2.2 m^(3)/(m^(3)×d))were achieved in R1 than R0 at the OLR of 25.0 kg/(m^(3)×d).Such favorable effect results from the facts that fungi inhibit VFAs accumulation,favor the pH stabilization,promote the generation of more extracellular polymeric substance,and enhance the sludge granulation and ***,fungi may enhance the secretion of acetyl-coenzyme A,a key compound in converting organic matters to CO_(2).In addition,fungi are favorable to enrich methanogenic archaea even at high OLR,improving the activity of acetate kinase and coenzyme F_(420) for more efficient methanogenic *** work may shed new light on how to achieve higher OLR and methane production in anaerobic digestion of wastewater.

关键词： Anaerobic digestion Fungi Methane production High OLR Microbial community

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

Antimony(V) removal from water by hydrated ferric oxides supported by calcite sand and polymeric anion exchanger

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Journal of Environmental Sciences 2014年第2期26卷 307-314页

作者： Yangyang Miao Feichao Han bingcai pan Yingjie Niu Guangze Nie Lu Lv State Key Laboratory of Pollution Control and Resources Reuse School of the Environment Xianlin Campus Nanjing University

We fabricated and characterized two hybrid adsorbents originated from hydrated ferric oxides （HFOs） using a polymeric anion exchanger D201 and calcite as host. The resultant adsorbents （denoted as HFO-201 and IOCCS） were employed for Sb（V） removal from water. Increasing solution pH from 3 to 9 apparently weakened Sb（V） removal by both composites, while increasing temperature from 293 to 313 K only improved Sb（V） uptake by IOCCS. HFO-201 exhibited much higher capacity for Sb（V） than for IOCCS in the absence of other anions in solution. Increasing ionic strength from 0.01 to 0.1 mol/L NaNO3 would result in a significant drop of the capacity of HFO-201 in the studied pH ranges; however, negligible effect was observed for 1OCCS under similar conditions. Similarly, the competing chloride and sulfate pose more negative effect on Sb（V） adsorption by HFO-201 than by IOCCS, and the presence of silicate greatly decreased their adsorption simultaneously, while calcium ions were found to promote the adsorption of both adsorbents. XPS analysis further demonstrated that preferable Sb（V） adsorption by both hybrids was attributed to the inner sphere complexation of Sb（V） and HFO, and Ca（II） induced adsorption enhancement possibly resulted from the formation of HFO-Ca-Sb complexes. Column adsorption runs proved that Sb（V） in the synthetic water could be effectively removed from 30 μg/L to below 5μg/L （the drinking water standard regulated by China）, and the effective treatable volume of IOCCS was around 6 times as that of HFO-201, implying that HFO coatings onto calcite might be a more effective approach than immobilization inside D201.

关键词： hydrated ferric oxides antimony nanocomposite adsorbents calcite anion exchanger