Selective leaching of arsenic from copper converter flue dust by Na2S and its stabilization with Fe2(SO4)3

The alkaline leaching of arsenic (As2O3) by Na2S, together with its precipitation by Fe2(SO4)3 was studied. Response surface methodology based on central composite design was employed to quantify and qualify the effect of pertinent factors and to develop statistical models for optimization purposes. Based on the obtained results, 89% of arsenic is removed from the dust under following optimum predicted conditions: Na2S concentration of 100 g/L and solid to liquid ratio of 0.163 g/mL at 80 °C. It is found that solid to liquid ratio and Na2S concentration are the significant factors influencing the leaching process. In the precipitation process, more than 99.93% of arsenic from the leaching solution is removed in the form of amorphous ferric arsenate, at pH 4.8 when Fe3+ to arsenic and H2O2 to arsenic molar ratios are set at 5:1 and 4:1, respectively. Also, Fe3+ to arsenic ratio and pH are the most significant factors, and the interaction between these terms is significant.

Preparation of alkaline-responsive nano-electrospinning and anticorrosion properties of self-healing coating

In this paper,1-butyl-3-methylimidazole tetrafluoroborate([BMIM]BF4)is used as corrosion inhibitor.Polyacrylonitrile(PAN)is used to load the corrosion inhibitor.PAN/[BMIM]BF4 hybrid nanofibers are successfullysynthesized by electrospinning technology.The alkyd varnish is coated on the fiber membrane to prepare a compositecoating,and then a series of tests are carried out on the self-healing and anticorrosive performance of the compositecoating.It is observed by scanning electron microscope that the fiber morphology is stable and there is no bead-likestructure.The composition of the composite fiber is analyzed by Fourier infrared spectroscopy,and it is confirmed thatthe hybrid nanofiber was successfully prepared.3D laser confocal scanning microscope was used to observe thecorrosion morphology and profile of the carbon steel.The composite coating shows good self-healing performance.[BMIM]BF4 can form a protective film on the surface of the bare carbon steel substrate through physical adsorption orchemical adsorption in an alkaline environment.Electrochemical impedance spectroscopy was tested and analyzed.It isfound that the maximum corrosion inhibition efficiency of the coating is 88.5%in 3.5 wt.%alkaline NaCl solution.Compared with the blank coating without nanofibers,the composite fiber varnish composite coating exhibits good selfhealingand anti-corrosion properties.