Fuxing Gan

A study on cathodic protection against crevice corrosion in dilute NaCl solutions

Potential and current distributions in a cathodically protected crevice between a simulated coating and segmented mild steel electrodes were measured in dilute NaCl solutions. The distributions became more uniform with time due to an increase in solution conductivity and depletion of dissolved oxygen in the crevice. Generally, a negative shift of control potential and an increase in initial solution conductivity and crevice thickness resulted in a higher polarization level on the steel. However, if the control potential is too negative, the polarization level may be lower than that under a suitable control potential because of hydrogen evolution. On the basis of these results, a mechanism of cathodic protection against crevice corrosion in high-resistivity environments was proposed

Comparison of the performances of Ti/SnO2-Sb, Ti/SnO2-Sb/PbO2, and Nb/BDD anodes on electrochemical degradation of azo dye

In this paper, the preparation conditions of antimony-doped SnO2 and PbO2 electrode were optimized for the degradation activity of AO7 dye solution. The results showed that when the doping content of Sb is 8 mol %(SnO2-Sb(0.08)), the SnO2 electrode exhibited best activities for the decolorization and mineralization of AO7. The concentration of NaF in electroplating solution had a noticeable effect on PbO2 electrode for the decolorization of AO7 solution, but little influence on the COD removal rate. The anodic stability tests showed that the electrode prepared in the solution containing 0.10 g l−1 NaF (PbO2-F(0.10)) was best for environmental application. The comparison of SnO2-Sb(0.08), PbO2-F(0.10) and Boron-doped Diamond (BDD) electrodes revealed that a more rapid decolorization rate was obtained on SnO2-Sb(0.08) and PbO2-F(0.10) electrodes in dilute AO7 solutions, while higher COD removal rate of concentrated AO7 solutions was on BDD and SnO2-Sb(0.08) electrodes. The effect of concentration of Na2SO4 on the degradation rate of AO7 was very notable on BDD electrode for its highest overpotential of oxygen evolution reaction. In the chloride-containing medium, the decolorization was accelerated greatly but the completed mineralization of AO7 was inhibited with the increasing of chloride ions concentration when these high-overvoltage anodes were used

PbO(2)-SnO(2) composite anode with interconnected structure for the electrochemical incineration of phenol

A PbO2-SnO2 composite anode with interconnected structure is prepared for organics electro-incineration through a two-step method, thermal-decomposition process and subsequent low-current density electrodeposition process. The element mapping, together with the impedance spectra of the composite electrode, confirms that an interconnected architecture of SnO2 and PbO2 grains, instead of a lamellar structure, was obtained on the Ti substrate. A lower electrodeposition current density (≤10 mA cm−2) is very crucial for the formation of a porous surface and an interconnected architecture of two oxides inside. The asprepared electrode exhibits an enhanced electrocatalytic activity on the mineralization of phenol and a long service life due to the interconnected architecture, which helps to utilize the merits of these two metal oxides simultaneously. This two-step method also provides us a novel and facile way to fabricate a series of composite material such as oxide-oxide, oxide-metal composite electrodes.

Enhanced electrochemical oxidation of phenol by introducing ferric ions and UV radiation

The mineralization of phenol in aerated electrochemical oxidation has been investigated. The results show that a cathodic Fenton process can occur when the Ti-0.3Mo-0.8Ni alloy material is used as cathode in solution containing ferric or ferrous ions; moreover, the reinforcement of cathodic Fenton process on the total organic carbon (TOC) removal rate of phenol is quite distinct. Among the metallic ions investigated, the ferric ion is the best catalyst for the electrochemical mineralization of phenol at initial pH 2.0, and the optimal concentration range is from 50 to 200 mg/L. The favorable pH range and supporting electrolyte (Na2SO4) concentration for mineralization of phenol in solution containing ferrous ions are 1.8-2.3 and below 0.10 mol/L, respectively. UV radiation can improve the TOC removal rate of phenol, but the enhanced effect varies in different solutions. In the solution containing ferric ions, an equal sum or synergetic effect can be observed. The optimal effect of electrolysis system under UV radiation is achieved in the solution containing 50 mg/L Fe3+ with a final removal percentage of 81.3%.

Preparation of non‐chromium polymer films on zinc for corrosion protection due to a compound effect between silane and cerium salt

[Fang, Da-jing; Mao, Xu-hui; Chen, Zhi-liang; Liu, Min; Gan, Fu-xing] Wuhan Univ, Sch Resource & Environm Sci, Wuhan 430072, Peoples R China. [Zhang, Ye-ming] Huangshi Inst Technol, Sch Environm Sci & Engn, Huangshi, Peoples R China. [Chen, Zhi-liang; Liu, Min; Gan, Fu-xing] State Key Lab Corros & Protect Met, Shenyang, Peoples R China.;Gan, FX (reprint author), Wuhan Univ, Sch Resource & Environm Sci, Wuhan 430072, Peoples R China,Peoples R China;fxgan@whu.edu.cn

A study on the filming kinetics of corrosion inhibitors in Fe/Na2SO4 system using EQCM

Abstract Electrochemical Quartz Crystal Microbalance (EQCM), a new electrochemical technique developed in recent years, has been employed to study the filming kinetics of corrosion inhibitors in Fe/Na2SO4 neutral system. An equation was deduced to calculate the real mass change of the electrode surface during the filming and some experimental isothermal curves of filming kinetics of corrosion inhibitors were found. It is found that the film growth on iron in Na2SO4 solution follows the parabolic law in the presence of the oxidizing inhibitor NaNO2, similar to oxidation kinetics of some metals at high temperature, or the linear law in the presence of the precipitating inhibitor Na2SiO3.

New Integrated Processes for Treating Cold-Rolling Mill Emulsion Wastewater

Two new integrated processes, gas-energy-management (GEM)—electrochemical catalytic oxidation (ECO)—membrane bioreactor (MBR) and ultrafiltration (UF)—ECO—MBR, in industrial-scale test for treating cold-rolling mill emulsion wastewater with water quantity of 200 L/h to 3 000 L/h were studied. The former was put forward firstly and the latter was applied initially in this field. The operation conditions and mechanisms of each module in the integrated processes were analyzed and the influences of operational parameters of two processes on chemical oxygen demand (CODCr) removal efficiency were comparatively investigated. The test results showed that the ultimate water quality from the two processes after treatment could meet the requirement for reuse. However, the quality of effluent treated by GEM—ECO—MBR was more stable than that of UF—ECO—MBR.

Study of an environment‐friendly insulating coating with high corrosion resistance on electrical steel

[Lin, An; Zhang, Xian; Fang, Dajing; Yang, Miao; Gan, Fuxing] Wuhan Univ, Sch Resource & Environm Sci, Dept Environm Engn, Wuhan 430072, Peoples R China. [Gan, Fuxing] State Key Lab Corros & Protect Met, Shenyang, Peoples R China.;Lin, A (reprint author), Wuhan Univ, Sch Resource & Environm Sci, Dept Environm Engn, Wuhan 430072, Peoples R China;linanwd@126.com

Treatment of Reused Comprehensive Wastewater in Iron and Steel Industry With Electrosorption Technology

Electrosorption technology was used to treat the reused comprehensive wastewater from iron and steel industry. A problem of relatively high conductivity of wastewater which greatly affects the reuse was examined, and industrial test was conducted for the reused water advanced deionization and purification in a comprehensive wastewater treatment plant of WISCO [Wuhan Iron and Steel (Group) Corporation]. The results of the on-site industrial test showed a satisfactory treatment performance for the reused water even at a flow rate of 1000 L/h in a standard 500 L/h unit. The average conductivity decreased by about 70%, from 580–780 μS/cm to 100–350 μS/cm. The average removal efficiency of Cl− and Ca2+ was about 75% and 68%, respectively, and CODCr, of the treated water was also reduced in some degree while the pH value was almost unchanged. The energy consumption was as low as 0. 6 kWh/t, which was remarkably superior to the conventional technologies. Therefore, it is entirely feasible that the novel electrosorption technology can be used in enhanced desalination and purification treatment of reused comprehensive wastewater in iron and steel industry.

A BIBLIOMETRIC ANALYSIS OF THE GLOBAL LITERATURE IN THE CORROSION FIELD FROM 1992 TO 2007

[Fang, Da-jing; Mao, Xu-hui; Zhang, Si-yu; Qiao, Yu-jie; Gan, Fu-xing] Wuhan Univ, Sch Resource & Environm Sci, Wuhan 430072, Peoples R China. [Zhang, Ye-ming] Huangshi Inst Technol, Sch Environm Sci & Engn, Huangshi 435003, Peoples R China. [Gan, Fu-xing] State Key Lab Corros & Protect Met, Shenyang 110016, Peoples R China.;Mao, XH (reprint author), Wuhan Univ, Sch Resource & Environm Sci, Wuhan 430079, Peoples R China;mao_faust@126.com