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Zhang L.,Central South University | Wang H.,Central South University | Wang H.,National Engineering Research Center for Heavy Metals Pollution Control and Treatment | Yu W.,Central South University | And 5 more authors.
Journal of Materials Chemistry | Year: 2012

Traditional chemical oxidative polymerization, with the procedure of gradually adding the oxidant, generally produces amine-containing conjugated polymer (NCP) microparticles. In this paper, an improved method has been developed through using a small amount of Cu 2+ prior to the polymerization for large-scale synthesis of poly(m-phenylenediamine) (PmPD, one typical NCP) nanoparticles. The Cu-monomer/oligomer complex nanoparticle structures formed before the polymerization are suitable intermediates to activate the polymerization and induce the morphology evolution of the PmPD nanostructures. A possible mechanism is that Cu ions at the centre of the complex mediate the electron transfer from ligand to persulfate oxidant, as analyzed by comparative experiments; Fourier transform infrared spectrometry (FTIR) and open-circuit potential of the polymerization. During the growth of macromolecular chains, the Cu ions are gradually released into the bulk solution from the complex. The nano-sized PmPD was used to adsorb a dye (Orange G) and showed high adsorbance of 387.6 mg g -1, which is on average 200 mg g -1 more than that of the microparticles. © 2012 The Royal Society of Chemistry.


Yu W.,Central South University | Zhang L.,Central South University | Wang H.,Central South University | Wang H.,National Engineering Research Center for Heavy Metals Pollution Control and Treatment | And 2 more authors.
Journal of Hazardous Materials | Year: 2013

Poly(m-phenylenediamine) (PmPD) with different oxidation state was successfully synthesized by the improved chemically oxidative polymerization. The function of oxidation state on Cr(VI) adsorption was systematically examined through adsorption experiments. Results showed that the Cr(VI) adsorptivity of all PmPD increased with decreasing the initial pH. When the oxidation state of PmPD was dropped, the equilibrium time for Cr(VI) adsorption was obviously shortened and its Cr(VI) removal and adsorption selectivity were profoundly obviously increased. Typically, PmPD with the lowest oxidation state in this research possesses the highest Cr(VI) removal of 500mgg-1. Moreover, PmPD with lower oxidation state displays a potentially superior prospect in Cr(VI) treatment through preliminary experiments on 5 cycles of adsorption, column adsorption and practical wastewater treatment. The possible adsorption mechanism was discussed mainly according to characterizations (FTIR, XPS) and experiments, which together suggests that the Cr(VI) adsorption most possibly involve redox reaction, chelation and doping adsorption. © 2013 Elsevier B.V..


Su Z.,Central South University | Zhang L.,Central South University | Chai L.,Central South University | Chai L.,National Engineering Research Center for Heavy Metals Pollution Control and Treatment | And 4 more authors.
RSC Advances | Year: 2013

Morphology and size of poly(m-phenylenediamine) (PmPD) can be tuned readily with conventional chemical oxidation by introducing methanol (MeOH). Increasing MeOH content facilitates the formation of one-dimensional (1D) PmPD microstructures. Typically, when the MeOH content is up to 100%, 1D nanorods were formed, displaying the Ag+ absorbability of 2073 mg g -1. © The Royal Society of Chemistry 2013.


Su Z.,Central South University | Zhang L.,Central South University | Chai L.,Central South University | Chai L.,National Engineering Research Center for Heavy Metals Pollution Control and Treatment | And 5 more authors.
New Journal of Chemistry | Year: 2014

A diethanolamine-assisted (DEA-assisted) conventional oxidation method was explored to synthesize the hollow nanostructures of poly(m-phenylenediamine) (PmPD) with a high specific surface area. The DEA concentration has a significant influence on the PmPD morphology and a possible formation mechanism has been proposed. The obtained hollow nanostructures show an excellent Ag + adsorption ability with an adsorbance of 2359.3 mg g-1, much higher than other reported materials. © 2014 the Partner Organisations.


Chai L.-Y.,Central South University | Chai L.-Y.,National Engineering Research Center for Heavy Metals Pollution Control and Treatment | Yu W.-T.,Central South University | Zhang L.-Y.,Central South University | And 2 more authors.
Micro and Nano Letters | Year: 2012

Hollow poly(m-phenylenediamine) (PmPD) microparticles were successfully synthesised with chemically oxidative polymerisation through rapidly mixing the persulphate oxidant solution with m-phenylenediamine solution at room temperature. In a further experiment, Na2CO3 was used to create a CO2 bubble to facilitate the formation of hollow PmPD microparticles. The morphology and molecular structure of the products were characterised with scanning electron microscopy, transmission electron microscopy and Fourier transmission infrared spectroscopy. The results showed that the PmPD possesses a mouth-like cave when synthesised without Na2CO3. More interestingly, using Na2CO3, the cave number and shape of PmPD microparticles change. The PmPD synthesised with or without Na2CO3 has similar functional groups but different oxidation state. © 2012 The Institution of Engineering and Technology.


Liao Y.,Central South University | Min X.,Central South University | Min X.,National Engineering Research Center for Heavy Metals Pollution Control and Treatment | Yang Z.,Central South University | And 5 more authors.
Environmental Science and Pollution Research | Year: 2014

Chemical and microbial methods are the main remediation technologies for chromium-contaminated soil. These technologies have progressed rapidly in recent years; however, there is still a lack of methods for evaluating the chemical and biological quality of soil after different remediation technologies have been applied. In this paper, microbial remediation with indigenous bacteria and chemical remediation with ferrous sulphate were used for the remediation of soils contaminated with Cr(VI) at two levels (80 and 1,276 mg kg-1) through a column leaching experiment. After microbial remediation with indigenous bacteria, the average concentration of water-soluble Cr(VI) in the soils was reduced to less than 5.0 mg kg-1. Soil quality was evaluated based on 11 soil properties and the fuzzy comprehensive assessment method, including fuzzy mathematics and correlative analysis. The chemical fertility quality index was improved by one grade using microbial remediation with indigenous bacteria, and the biological fertility quality index increased by at least a factor of 6. Chemical remediation with ferrous sulphate, however, resulted in lower levels of available phosphorus, dehydrogenase, catalase and polyphenol oxidase. The result showed that microbial remediation with indigenous bacteria was more effective for remedying Cr(VI)-contaminated soils with high pH value than chemical remediation with ferrous sulphate. In addition, the fuzzy comprehensive evaluation method was proven to be a useful tool for monitoring the quality change in chromium-contaminated soils. © 2013 Springer-Verlag Berlin Heidelberg.


Yu W.,Central South University | Zhang L.,Central South University | Meng Y.,Central South University | Dai S.,Central South University | And 5 more authors.
Synthetic Metals | Year: 2013

Conventional chemically oxidative polymerization was successfully improved through the cooperative effect of Cu2+ and NaOH (Cu-OH-assistance method for short) to satisfy the high conversion synthesis of poly(m-phenylenediamine) (PmPD) nanoparticles. The highest yield calculated from the mass of de-protonated and de-doped PmPD can reach 93.1%, which obviously lowers the potential pollution caused by the organic side-products left inside the solution after the polymerization. The PmPD obtained via the conventional polymerization procedure that is gradual addition of oxidant, which can induce secondary growth, is the nanoparticles. The possible mechanism on the high yield was discussed based on in situ open-circuit potential, pH detections and Fourier transformed infrared (FTIR) spectroscopy. Moreover, the Ag+ adsorption performance of the PmPD nanoparticles synthesized with the highest yield was investigated. It was found that the adsorbance within 5 min reached up to 61% of the final value. The Ag+ adsorbance of PmPD nanoparticles can be as high as ∼1767 mg g-1, which is much higher than most of the adsorbents up to date. © 2013 Elsevier B.V. All rights reserved.


Liao Y.,Central South University | Min X.,Central South University | Min X.,National Engineering Research Center for Heavy Metals Pollution Control and Treatment | Yang Z.,Central South University | And 6 more authors.
Journal of Soils and Sediments | Year: 2014

Purpose: Acid rain can accelerate the acidification of the chromium-contaminated soils, resulting in chromium releasing into soil solution and causing ecological risk. The current study aims to investigate the release of chromium in the remedied soils by Pannonibacter phragmitetus BB under the simulated acid rain leaching and to assess its risk to groundwater. Materials and methods: P. phragmitetus BB was utilized to remedy the Cr(VI)-contaminated soils at two levels (80 and 1,276 mg kg-1) by the column leaching experiment, and the chemical remediation with ferrous sulfate was used as a control. The remedied soils by P. phragmitetus BB and ferrous sulfate were leached under the simulated acid rain to evaluate the release of chromium. Furthermore, the risk of chromium release from the remedied soils to the groundwater was assessed by a fuzzy comprehensive evaluation method. Results and discussion: The average concentrations of water-soluble Cr(VI) in the remedied soils by P. phragmitetus BB were reduced to less than 5.0 mg kg-1. Under leaching situation with the simulated acid rain, the release of total chromium and Cr(VI) from the remedied soils by P. phragmitetus BB and ferrous sulfate declined rapidly with the extended leaching time. However, the release amounts of total chromium and Cr(VI) from the remedied soil by P. phragmitetus BB more efficiently deceased as compared with that by ferrous sulfate remediation. Carbonate-bounded, exchangeable, and organics-bonded chromium were the major chromium-releasing sources under the simulated rain leaching. After microbial remediation with P. phragmitetus BB and chemical remediation with ferrous sulfate, the risk grades of the remedied soils to groundwater declined from classes 11 to 5 and 6, respectively. Conclusions: The risks of the remedied soils by both microbial remediation with P. phragmitetus BB and chemical remediation with ferrous sulfate to groundwater effectively decreased and microbial remediation more significantly declined the chromium risk to groundwater than chemical remediation. © 2014 Springer-Verlag Berlin Heidelberg.

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