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Purpose – The purpose of this investigation was to synthesize a doped polyaniline-containing coating and investigate the anti-corrosion properties of the coating on Mg-Li alloy. Design/methodology/approach – The doped polyaniline pigments were prepared by two different methods using ammonium persulphate as oxidant and hydrochloric acid, phosphoric acid, p-toluene sulfonic acid and sulfosalicylic acid as doping agents. The doped polyaniline was characterized by Fourier transform infrared (FT-IR) analysis, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The coatings consisted of polyaniline, epoxy resin and other additives that were formed on Mg-Li alloy. The anti-corrosion properties of the polyaniline-containing coating on the Mg-Li alloy were investigated in 3.5 wt.% NaCl solution using open circuit potential logging and electrochemical impedance spectroscopy. Findings – The results of the electrochemical tests indicated that the polyaniline-containing coatings showed better anti-corrosion properties, as compared to conventional epoxy coatings on Mg-Li alloy when exposed in 3.5 wt.% NaCl solution. The coating containing 2 wt.% polyaniline (relative to the mass of epoxy resin) doped with hydrochloric acid had the best anti-corrosion properties on the Mg-Li alloy. Originality/value – Previous reports on the anti-corrosion properties of polyaniline-containing coatings focused mainly on the surface of iron, steel, aluminum and magnesium, and there have been few studies on the anti-corrosion properties as protective coatings for Mg-Li alloy. [ABSTRACT FROM AUTHOR]

Characteristics and optimal reaction conditions of anaerobic azoreduction by the Shewanella decolorationis S12 in the presence of zero-valent iron (ZVI) were evaluated in this study. The results showed that the presence of ZVI significantly enhanced the decolorization rate of azo dye. In the presence of 20 mmol x L(-1) ZVI, the decolorization rate of 1 mmol x L(-1) amaranth reached up to 100% by the Shewanella decolorationis S12 after 30 h incubation, which was significantly higher than 23.16% and 94.66% in the pure strain S12 and pure ZVI treatment systems, respectively. When 20 mmol x L(-1) of sodium formate was added in the medium, ZVI still improved the decolorization rate of amaranth by 20.54%. In addition, the presence of ZVI significantly increased the azo dye treatment amount in the ZVI plus S12 system. In the system with ZVI, 1 mmol x L(-1) amaranth was completely reduced 11 times in fed-batch process within 276 h, while the dye could only be completely reduced 3 times in the system without ZVI. The optimal pH and the Fe(0) dose for the ZVI plus S12 system was 9.0 and 60 mmol c L(-1), respectively. The microscale ZVI was more suitable for the decolorization than those with larger size and the nanoscale ZVI. This study may provide some useful information for improving the biodegradation of azo dye in the treatment system with ZVI.

The effects of soluble and insoluble Fe(III) on anaerobic azoreduction by Shewanella decolorationis S12 were examined in a series of experiments. Results showed that the effects of iron on anaerobic azoreduction depended on the solubility and concentration of the compounds. Azoreduction was inhibited by insoluble Fe(III) and 0.05-2 mmol/L Fe2 O3 all decelerated the azoreduction activity of 0.2 mmol/L amaranth, but the increase in the concentrations of Fe2O3 did not cause an increasing inhibition. Soluble Fe(III) of which concentration less than 0.4 mmol/L enhanced azoreduction activity of 0.2 mmol/L amaranth but there was no linear relationship between the concentration of soluble Fe(III) and azoreduction activity. Soluble Fe(III) of which concentration more than 1 mmol/L inhibited azoreduction activity of 0.2 mmol/L amaranth and an increasing concentration resulted in an increased inhibition. The inhibition was strengthened under the conditions of limited electron donor. On the other hand, soluble Fe(III) and Fe(II) could relieve the inhibition of azoreduction by dicumarol which blocked quinone cycle. It suggests that in addition to quinone cycle, there is a Fe(III) <--> Fe(II) cycle shuttling electrons in cytoplasmic and periplasmic environment. That is the reason why low concentration of soluble Fe(III) or Fe (II) can enhance azoreduction of S. decolorationis S12. It also indicates that insoluble Fe(III) and high concentration of soluble Fe(III) do compete with azo dye for electrons once it acts as electron acceptor. Thus, when iron and azo dye coexisted, iron could serve as an electron transfer agent or electron competitive inhibitor for anaerobic azoreduction under different conditions. High efficiency of azoreduction can be achieved through controlling the solubility and concentration of irons.

Experimental results suggested Shewanella cinica D14T is capable of humus respiration utilizing various organic acids and some important environmental pollutants (e.g., toluene. etc) as electron donors and AQS or AQDS as a sole terminal electron acceptor under anaerobic condition. The dissimilatory reduction of 1mmol/L AQDS can couple to the production of enough ATP to support cell growth about 60 generations; The oxidization of electron donors was coupled to the reduction of humus, as reduced humus increased corresponding with increasing of electron donor; The typical inhibitors such as Cu2+ which inhibited Fe-S center, Stigmatellin which was methyl-naphthoquinone model, Dicumarol which inhibited oxidized methyl-naphthoquinone transform to reduced one, Metyrapone which was specific inhibitor for P450 enzyme blocked the humus respiration seriously. These were powerful evidences for humus-respiration by D14.