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Xiao X.,South China University of Technology | Xiao X.,The Key Laboratory Of Environmental Protection And Eco Remediation Of Guangdong Regular Higher Edu Institute | Huang S.,South China University of Technology | Huang S.,The Key Laboratory Of Environmental Protection And Eco Remediation Of Guangdong Regular Higher Edu Institute
Huanjing Kexue Xuebao/Acta Scientiae Circumstantiae | Year: 2012

A mercury resistant strain, X1, was screened out from efficient aerobic denitrifying bacteria. It was identified as Pseudomonas putida according to its physiological properties and the analysis of its 16S rRNA gene sequence. Study on its adaptive characteristics to Hg 2+ showed that, for the experimental groups containing 2, 4, 6, 7 mg·L -1 of Hg 2+, bacteria need to be delayed for 12, 18, 28, 40 h respectively to enter the logarithmic period, with the 8mg·L -1 group unable to enter the logarithmic period. In the process of aerobic denitrification, concentration change rate of NO 3 --N, accumulated peak of NO 2 --N and pH characteristic points had same change trend with concentration of Hg 2+, while concentration of Hg 2+ showed the same downward trend as NO 3 --N, and could be removed by 100% during logarithmic period. It can thus be concluded that the concentration limit was 7 mg·L -1 and the corresponding adaptive time was 40 h. Within the concentration limit, the growth and aerobic denitrification process would present a "Suppression-adaptation-stimulation" pattern. The pent-up time and stimulated degree would both increase with the increase of Hg 2+ concentration, which was mainly reflected by longer adapting period and shorter logarithm period. In addition, during logarithm period, its growth rate, stabilization concentration and aerobic denitrification rate also increased with the increase of Hg 2+ concentration and were all larger than blank group. Source

Lan Y.,South China University of Technology | Lan Y.,The Key Laboratory Of Environmental Protection And Eco Remediation Of Guangdong Regular Higher Edu Institute | Luo H.,South China University of Technology | Luo H.,The Key Labof Pollution Control And Ecosystem Restoration In Industry Clusters Of Ministry Of Edu | And 6 more authors.
Analytical Letters | Year: 2012

The electrochemical detection of As(III) was investigated on the novel citrate stabilized gold nanoparticle modified glassy carbon electrode (AuNPs/GCE) in 1 M HCl by square wave anodic stripping voltammetry. AuNPs/GCE was prepared by simply casting citrate stabilized gold nanoparticles onto the well-polished glassy carbon electrode. Gold modification was evaluated by cyclic voltammetry, while transmission electron microscopy and UV-vis Spectroscopy revealed the size and distribution of gold nanoparticles. Anodic stripping voltammetry was performed with the modified electrode in As(III) solution. Electrochemical experiments proved that AuNPS/GCE exhibited good performance for As(III) analysis, the linear range were obtained between 0.05 and 1 ppb for trace level of As(III) as well as 1 to 15 ppb, with a limit of detection of 0.025 ppb. In terms of reproducibility, the precision of the aforementioned method in %RSD was calculated at 7.78% (n = 10), and the repeatability of the proposed method was calculated to be 1.59%. The application of the method to analyze As(III) in tap water was investigated. © 2012 Copyright Taylor and Francis Group, LLC. Source

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