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Xu Z.,Nanjing University | Zhang W.,Nanjing University | Zhang W.,National Engineering Research Center for Organic Pollution Control and Resources Reuse | Lv L.,Nanjing University | And 3 more authors.
Environmental Science and Technology

In the present study, a novel approach was developed to remove dimethyl phthalate (DMP), a representative phthalic acid ester (PAE) pollutant, from an aqueous solution using a macroporous OH-type strong base anion exchange resin D201-OH. As compared to the traditional catalyst aqueous NaOH, D201-OH displayed much higher catalytic efficiency for DMP hydrolytic degradation. Almost 100% of DMP was hydrolyzed to far less toxic phthalic acid (PA) in the presence of D201-OH, while only about 29% of DMP was converted to PA in the presence of NaOH under the identical amount of hydroxyl anions in the reaction system. More attractively, the hydrolysis product PA also can be simultaneously removed by the solid basic polymer D201-OH through a preferable anion exchange process, while NaOH induced hydrolysis products were still left in solution. The underlying mechanism for the hydrolytic degradation and simultaneous ion exchange removal process was proposed. Fixed-bed column hydrolytic degradation and ion exchange removal tests indicate that DMP can be completely converted to PA and subsequently removed from water without any further process, with pH values of the effluent being around 6 constantly. The exhausted D201-OH was amenable to an efficient regeneration by 3 bed volumes (BV) of NaOH solution (2 mol/L) for repeated use without any efficiency loss. The results reported herein indicated that D201-OH-induced catalytic degradation and removal is a promising approach for PAEs treatment in waters. © 2010 American Chemical Society. Source

Xu Z.,Nanjing University | Zhang W.,Nanjing University | Zhang W.,National Engineering Research Center for Organic Pollution Control and Resources Reuse | Pan B.,Nanjing University | And 2 more authors.
Environmental Technology

To study the adsorptive separation efficiency, adsorption and desorption performances of diethyl phthalate (DEP) were investigated with a functional polymer resin (NDA-702). A macroporous polymer resin (XAD-4) and a coal-based granular activated carbon (AC-750) were chosen for comparison. The kinetic adsorption data obeyed the pseudo-second-order rate model, and the adsorption processes were limited by both film and intraparticle diffusions. Adsorption equilibrium data were well fitted by the Freundlich equation, and the larger uptake and higher selection of NDA-702 than AC-750 and XAD-4 was probably due to the microporous structure, phenyl rings and polar groups on NDA-702. Thermodynamic adsorption studies indicated that the test adsorbents spontaneously adsorbed DEP, driven mainly by enthalpy change. Continuous fixed-bed runs demonstrated that there no significant loss of the resin's adsorption capacity and there was complete regeneration of NDA-702. The results suggest that NDA-702 has excellent potential as an adsorption material for water treatment. © 2011 Taylor & Francis. Source

Wang J.,Nanjing University | Li H.,Nanjing University | Li H.,National Engineering Research Center for Organic Pollution Control and Resources Reuse | Shuang C.,Nanjing University | And 6 more authors.
Microporous and Mesoporous Materials

A series of magnetic anion exchange resins (ND-1, ND-2 and ND-3) with different pore structure were prepared for ibuprofen (IBU) adsorption by using different amount of cyclohexanol as porogen in this work. For adsorption kinetics, resins with larger pore structure showed faster adsorption rates and higher equilibrium adsorption capacities because the internal diffusion process was facilitated by the increase of pore diameter and pore volume. As for adsorption isotherms, the experimental data was better fitted by Freundlich model especially for the resins with broader pores, suggesting that heterogeneous interactions took place in pores. The counter ion released by resin was measured, and ratios of equilibrium adsorption capacity to the counter ion were between 1.22 and 1.56, which confirmed that adsorption process was predominantly attributed to ion exchange while other interactions also existed. Hence, the co-existent anion reduced the adsorption amount of IBU onto resin by competing adsorption in ion exchange process, and the optimal pH ranged from 6 to 8. Resins with more open structure showed better regeneration abilities, of which the adsorption amounts witnessed no significant decrease during 7 circles of use, indicating the advantages of larger pore canal in the adsorption and regeneration behavior. © Elsevier Inc. All rights reserved. Source

Song H.,Nanjing University | Song H.,National Engineering Research Center for Organic Pollution Control and Resources Reuse | Song H.,Nanjing University of Technology | Wu Y.,Nanjing University | And 8 more authors.
Electrochimica Acta

Capacitive deionization (CDI) is an emerging technology that supplies deionized water to resolve the fresh water shortage. CDI electrodes are mainly made up of carbon materials, of which the deionization performance is closely related to their physical properties and structures. Hence, a rational design of electrode material structure is essentially significant. Functionalized graphene (fG) in particular has recently been regarded as characteristic CDI electrode material. However, preparation of fG based on graphene oxide usually results in serious secondary pollution due to usage of highly poisonous chemicals, and thus still cannot meet the demand of practical application. It is feasible that environmentally-friendly activated carbon (AC) and small amounts of fGs can be combined rationally, and used as CDI electrodes. Here, sono-assembled AC/m-phenylenediamine (mPEA) or p-phenylenediaminefG inter-connected network architecture has been constructed for the first time successfully. The specific capacitances of the AC/fG composites were found to be significantly higher than that of the AC electrode owing to mesoporous generation. Also, among all the samples, the AC composite with 5 wt % mPEA-fG exhibited an ultrahigh electrosorption capacity of 12.58 mg/g (or 0.22 mmol/g) in NaCl solution. These observations indicate that fG can serve as an efficient conductive bridge to decrease the aggregation of AC particles, and improve the electron transfer with the composite electrode. This work provides an effective strategy for the environmental and economical electrode architectures for general applications in CDI and energy storage. © 2016 Elsevier Ltd. All rights reserved. Source

Chen Y.,Nanjing University | Chen Y.,National Engineering Research Center for Organic Pollution Control and Resources Reuse | Pan B.,Nanjing University | Pan B.,Nanjing Forestry University | And 6 more authors.
Environmental Science and Technology

A novel hybrid adsorbent D001-PEI was fabricated for selective Cu(II) removal by immobilizing soluble polyethyleneimine (PEI) nanoclusters within a macroporous cation exchange resin D001. Negligible release of PEI nanoclusters unexpectedly observed during operation may result from the porous cross-linking nature of D-001 as well as the electrostatic attraction between PEI and D001. Increasing solution pH from 1 to 6 results in more favorable Cu(II) retention by D001-PEI, and Cu(II) adsorption onto D001-PEI follows the Langmuir model and the pseudosecond-order kinetic model well. Compared to the host cation exchanger D001, D001-PEI displays more preferable adsorption toward Cu(II) in the presence of competing Mg2+, Ca2+, Sr2+ at greater levels in solution. Fixed-bed adsorption runs showed that Cu(II) sequestration on D001-PEI could result in its conspicuous decrease from 5 mg/L to below 0.01 mg/L. Also, the spent hybrid adsorbent can be readily regenerated by 6-8 BV HCl (0.2 mol/L)-NaCl (0.5 mol/L) binary solution for repeated use with negligible capacity loss. The results reported herein validate that D001-PEI is a promising adsorbent for enhanced removal of Cu(II) and other heavy metals from waste effluents. © 2010 American Chemical Society. Source

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