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Nie H.,South China University of Technology | Zhu N.,South China University of Technology | Zhu N.,The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters of Ministry of Education | Zhu N.,The Key Laboratory of Environmental Protection and Eco Remediation of Guangdong Regular Higher Education Institutions | And 5 more authors.
Applied Biochemistry and Biotechnology | Year: 2015

The bioleaching parameters of metal concentrates from waste printed circuit boards by Acidithiobacillus ferrooxidans immobilized on cotton gauze in a two-step reactor were investigated in this study. The results indicated that an average ferrous iron oxidation rate of 0.54 g/(L·h) and a ferrous iron oxidation ratio of 96.90 % were obtained after 12 h at aeration rate of 1 L/min in bio-oxidation reactor. After 96 h, the highest leaching efficiency of copper reached 91.68 % under the conditions of the content of the metal powder 12 g/L, the retention time 6 h, and the aeration rate 1 L/min. The bioleaching efficiency of copper could be above 91.12 % under repeated continuous batch operation. Meanwhile, 95.32 % of zinc, 90.32 % of magnesium, 86.31 % of aluminum, and 59.07 % of nickel were extracted after 96 h. All the findings suggested that the recovery of metal concentrates from waste printed circuit boards via immobilization of A. ferrooxidans on cotton gauze was feasible. © 2015 Springer Science+Business Media New York


Shi C.,South China University of Technology | Zhu N.,South China University of Technology | Zhu N.,The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters of Ministry of Education | Zhu N.,The Key Laboratory of Environmental Protection and Eco Remediation of Guangdong Regular Higher Education Institutions | And 5 more authors.
World Journal of Microbiology and Biotechnology | Year: 2015

The heavy metals content and dewaterability of municipal sewage sludge (MSS) are important parameters affecting its subsequent disposal and land application. Six kinds of inoculums were prepared to examine the characteristics of heavy metals removal and MSS dewaterability improvement in bioleaching processes. The results showed that Cu, Zn and Cd bioleaching efficiencies (12 days) were 81–91, 87–93 and 81–89 %, respectively, which were significantly higher than those of Fe–S control (P < 0.05) and blank control (P < 0.01). The bioleaching boosted by the prepared inoculums could also significantly enhance MSS dewaterability (P < 0.01). The centrifugal dehydration efficiency of MSS rose from 73.00 to 90.00 % at day 12. Microscopic observations and energy dispersive spectrum analysis demonstrated that the dewaterability improvement might be attributed to the changes of sludge structure from flocculent to obvious granular and the formation of secondary minerals mainly consisting of iron, oxygen and sulfur elements. The results above demonstrated that bacterial consortium enriched from acid mine drainage (AMD) was suitable to boost sludge bioleaching for heavy metals removal and dewaterability improvement. It also suggested that the synergy of sulfur/ferrous-oxidizing bacteria (SFOB) enriched from AMD and the cooperation of exogenous and indigenous SFOB significantly promoted bioleaching efficiencies. © 2015, Springer Science+Business Media Dordrecht.


Yang C.,South China University of Technology | Zhu N.,South China University of Technology | Zhu N.,The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters of Ministry of Education | Zhu N.,The Key Laboratory of Environmental Protection and Eco Remediation of Guangdong Regular Higher Education Institutions | And 5 more authors.
Journal of Material Cycles and Waste Management | Year: 2015

The goal of this study is to determine the potential of Acidithiobacillus ferrooxidans strain Z1 in bioleaching of metal concentrates of waste printed circuit boards (PCBs). The influences of initial pH, initial Fe(II) concentration, metal concentrates dosage, inoculation quantity and particle size on the bioleaching process were investigated and optimum conditions were determined. The results showed that 92.57 % copper leaching efficiency was achieved within 78 h in a two-step process, and 85.24 % aluminum and 95.18 % zinc were leached out after 183 h under the optimum conditions of initial pH 2.25, initial Fe(II) 9 g/L, metal concentrates dosage 12 g/L, inoculation quantity 10 % and particle size 0.178–0.250 mm. It demonstrated that metals could be efficiently leached from metal concentrates by Acidithiobacillus ferrooxidans Z1 and the bioleaching period was reduced 81–78 h. Therefore, the strain Acidithiobacillus ferrooxidans Z1 could be suggested as a potential strain to bioleach metals from metal concentrates of waste PCBs. © 2015 Springer Japan


Zhu N.,South China University of Technology | Zhu N.,The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters of Ministry of Education | Zhu N.,Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling | Cao Y.,South China University of Technology | And 5 more authors.
Environmental Science and Pollution Research | Year: 2016

Recovery of gold from aqueous solution using simple and economical methodologies is highly desirable. In this work, recovery of gold as gold nanoparticles (AuNPs) by Shewanella haliotis with sodium lactate as electron donor was explored. The results showed that the process was affected by the concentration of biomass, sodium lactate, and initial gold ions as well as pH value. Specifically, the presence of sodium lactate determines the formation of nanoparticles, biomass, and AuCl4 − concentration mainly affected the size and dispersity of the products, reaction pH greatly affected the recovery efficiency, and morphology of the products in the recovery process. Under appropriate conditions (5.25 g/L biomass, 40 mM sodium lactate, 0.5 mM AuCl4 −, and pH of 5), the recovery efficiency was almost 99 %, and the recovered AuNPs were mainly spherical with size range of 10–30 nm (~85 %). Meanwhile, Fourier transforms infrared spectroscopy and X-ray photoelectron spectroscopy demonstrated that carboxyl and amine groups might play an important role in the process. In addition, the catalytic activity of the AuNPs recovered under various conditions was testified by analyzing the reduction rate of p-nitrophenol by borohydride. The biorecovered AuNPs exhibited interesting size and shape-dependent catalytic activity, of which the spherical particle with smaller size showed the highest catalytic reduction activity with rate constant of 0.665 min−1. © 2016 Springer-Verlag Berlin Heidelberg


Wu Y.,South China University of Technology | Wu Y.,The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters of Ministry of Education | Luo H.,South China University of Technology | Luo H.,The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters of Ministry of Education | Wang H.,Hunan University
Separation Science and Technology (Philadelphia) | Year: 2014

Different surfactant-modified hydroxo aluminum/graphene nanocomposites were synthesized and used for the adsorptive decolorization of Congo red from aqueous solution. Nanocomposites were prepared by the intercalation of hydroxo aluminum/graphene oxide with three different surfactants, followed by reduction using sodium borohydride. Batch experiments were conducted to evaluate the adsorbance from aqueous solution using different adsorbents under different conditions. The results showed that the maximum adsorption capacity can reach 497.51 mg/g, 398.4 mg/g, and 352.1 mg/g on different adsorbents at pH 3 and 323 K. The as-prepared adsorbents all had good reusability, and the optimal eluent buffer is ethanol, NaOH and HCl for different adsorbents. The adsorption kinetics fitted well with a pseudo-second-order model. Adsorption data were found to fit well with the Freundlich model. The thermodynamic analysis indicated that these adsorptions were endothermic and spontaneous in nature. ©, Taylor & Francis Group, LLC.


Wu Y.,South China University of Technology | Wu Y.,The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters of Ministry of Education | Luo H.,South China University of Technology | Luo H.,The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters of Ministry of Education | And 2 more authors.
Environmental Science and Pollution Research | Year: 2015

To improve the photocatalytic efficiency of chromium-based metal−organic framework (MIL-101) photocatalyst, Pd nanoparticles and reduced graphene oxide were used to modify the MIL-101 via a facile method. The resulting novel photocatalyst was characterized by UV–vis diffuse reflectance spectra (DRS), powder X-ray diffraction (XRD), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). It was indicated that the photocatalyst afforded high photocatalytic efficiency for degradation of two triphenylmethane dyes, brilliant green and acid fuchsin, under exposure to visible light irradiation. Cyclic experiments demonstrated that the photocatalyst showed good reusability and stability for the dye degradation. © 2015, Springer-Verlag Berlin Heidelberg.


Huang J.,South China University of Technology | Zhu N.,South China University of Technology | Zhu N.,The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters of Ministry of Education | Cao Y.,South China University of Technology | And 4 more authors.
Applied Biochemistry and Biotechnology | Year: 2014

An electrogenic bacterium, named Citrobacter freundii Z7, was isolated from the anodic biofilm of microbial fuel cell (MFC) inoculated with aerobic sewage sludge. Cyclic voltammetry (CV) analysis exhibited that the strain Z7 had relatively high electrochemical activity. When the strain Z7 was inoculated into MFC, the maximum power density can reach 204.5 mW/m2 using citrate as electron donor. Series of substrates including glucose, glycerol, lactose, sucrose, and rhammose could be utilized to generate power. CV tests and the addition of anode solution as well as AQDS experiments indicated that the strain Z7 might transfer electrons indirectly via secreted mediators. © 2014, Springer Science+Business Media New York.


Yang Z.,South China University of Technology | Yang Z.,The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters of Ministry of Education | Zhang L.,South China University of Technology | Zhang L.,The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters of Ministry of Education | And 8 more authors.
Desalination and Water Treatment | Year: 2015

Abstract: A laboratory study was conducted to investigate the use of Mg/Fe hydrotalcite-like compounds for the removal of nitrate from synthetic solution. A series of calcined hydrotalcites (CHTlcs) with different chemical composition were investigated to remove nitrate. The highest nitrate percentage of adsorption (about 95%) and adsorption capacity (about 70 mg/g) were obtained by using the CHTlcs with Mg/Fe molar ratio of 3. The adsorption experiments were carried out under various equilibration conditions, such as adsorbent dose, pH, temperature, and competitive ions. It was found that 1.5 g/L Mg/Fe CHTlcs could achieve ideal adsorption efficiencies of nitrate during the nitrate adsorption process with an initial nitrate concentration of 100 mg/L at pH 8 and at temperature 30°C. Various co-existing anions interfered in the adsorption of nitrate. The inhibitory effect was in the order of phosphate > sulfate > chloride. Adsorption isotherms showed that the experimental equilibrium data was fitted better by the Langmuir isotherm model than the Freundlich. The adsorption kinetics was successfully fitted by pseudo-second-order kinetics. And the characterization of the Mg/Fe CHTlcs was also analyzed to validate adsorption process. Results showed promising utility of Mg/Fe CHTlcs that could be developed into a viable technology for nitrate removal from water. © 2014 Balaban Desalination Publications. All rights reserved.


Shi C.,South China University of Technology | Zhu N.,South China University of Technology | Zhu N.,The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters of Ministry of Education | Cao Y.,South China University of Technology | And 2 more authors.
Nanoscale Research Letters | Year: 2015

The development of green procedure for the synthesis of gold nanoparticles (AuNPs) has gained great interest in the field of nanotechnology. Biological synthetic routes are considered to be environmentally benign and cost-effective. In the present study, the feasibility of AuNPs’ synthesis via intracellular protein extract (IPE) of Pycnoporus sanguineus was explored. The characteristics of generated particles of formation, crystalline nature, and morphology and dimension were analyzed by UV-vis spectroscopy, X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. UV-vis spectra exhibited strong absorption peaks in 520 to 560 nm, indicating the formation of AuNPs. XRD analysis revealed that the formed AuNPs were purely crystalline in nature. TEM observation showed that AuNPs with various shapes including spherical, pseudo-spherical, triangular, truncated triangular, pentagonal, and hexagonal, ranging from several to several hundred nanometers, were synthesized under different conditions. The average size of AuNPs decreased from 61.47 to 29.30 nm as the IPE addition increased from 10 to 80 mL. When the initial gold ion concentration changed from 0.5 to 2.0 mM, the average size rose from 25.88 to 51.99 nm. As in the case of solution pH, the average size was 84.29 nm with solution pH of 2.0, which diminished to 6.07 nm with solution pH of 12.0. Fourier transform infrared (FTIR) analysis implied that the functional groups including hydroxyl, amine, and carboxyl were involved in the reduction of gold ions and stabilization of AuNPs. The catalysis results showed that 0.019 mg of AuNPs with average size of 6.07 nm could catalyze the complete degradation of 12.5 μmol of 4-nitroaniline within 6 min and the degradation rate increased drastically with the addition of AuNPs. All the results suggested that the IPE of P. sanguineus could be potentially applied for the eco-friendly synthesis of AuNPs. © 2015, Shi et al.; licensee Springer.


Yang Z.,South China University of Technology | Yang Z.,The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters of Ministry of Education | Mo Z.,South China University of Technology | Niu X.,South China University of Technology | Niu X.,The Key Laboratory of Pollution Control and Ecosystem Restoration in Industry Clusters of Ministry of Education
Separation Science and Technology (Philadelphia) | Year: 2015

The calcined layered double hydroxides (CLDHs) with 3:1 Mg/Al molar ratio were observed to acquire a high removal efficiency of perchlorate. And they were applied into perchlorate adsorption process with the initial 100 mg/L perchlorate solution in order to analyze removal efficiencies of perchlorate on various influential factors. The results represented that 1.5 g/L CLDHs could achieve ideal adsorption efficiencies of perchlorate at the pH range of 7–9 and at the temperature of 25°C. The removal efficiencies of perchlorate increased up to a maximum efficiency with the increasing dose of CLDHs. Acidic or highly alkaline environment adversely affected perchlorate adsorption. The adsorption process was found to be endothermic due to the higher adsorption capacity in CLDHs with the increasing temperature. The removal of perchlorate was best represented by the pseudo second-order kinetics model and Langmuir isotherm model. Co-existing anions tests showed that the anions of higher valence had a more significant effect than the monovalent anions during the adsorption process. Finally, the adsorption process was further validated by the X-ray patterns and Fourier-transform Infrared spectra of CLDHs. Results demonstrated potential utility of CLDHs that could be developed into a viable technology for perchlorate removal from water. ©, Taylor & Francis Group, LLC.

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