Magnetic bio-activated carbons production using different process parameters for phosphorus removal from artificially prepared phosphorus-rich and domestic wastewater.

A series of magnetic bio-activated carbon (MBAC) has been produced from lignin and ferrous salts following to the process including impregnation, carbonization, and steam activation. The influence of the impregnation methods and the steam flow rate on the quality and the maximum phosphorus adsorption capacity of the produced MBACs has been investigated. The phosphorus adsorption performance in real domestic wastewater of the MBAC with the highest maximum phosphorus adsorption capacity has been investigated. The results show that all of the produced MBACs have a relatively rich porous structure, and all surface iron species exist as magnetite (Fe3O4). Compared with the MBACs that are produced via the dry impregnation method using a lower steam flow rate, the MBACs that are produced via the wet impregnation method using a higher steam flow rate are believed to have a higher iron content and better iron species dispersion. The highest maximum phosphorus adsorption capacity of all the produced MBACs is estimated to be as high as 69.80 mg-P/g according to the best-fitting Langmuir model. The MBAC that shows the highest maximum phosphorus adsorption capacity could also remove 84.65% and 96.97% of the total phosphorus from the filtered raw domestic wastewater (FRDW) and treated domestic wastewater (TDW), respectively, which indicates a good potential for using MBACs for domestic wastewater treatment.

Diffusion Modelling on the Microstructure Evolution in MCrAlY-Superalloy System.

Elemental diffusion drives the microstructure development in the MCrAlY-superalloy systems at high temperature. In this paper, two diffusion models were built to simulate the diffusion behavior of elements in the coating or in the coating-substrate system. Firstly, a core-shell model was set up to investigate the thermodynamic and kinetic behavior of the localized microstructure. The results of the simulation successfully explained the mechanism of the formation of α(core)-γ'(shell) structure at lower temperature (750 °C) and γ(core)-ß(shell) structure at higher temperature (1100 °C). Secondly, a coating-substrate planner model was used to simulate the interdiffusion of elements between the MCrAlY coating and the superalloy substrate. The simulation results in the Ni22Cr10AlY-superalloy system semiquantitatively agreed with the experimental observation. Furthermore, by applying the planner diffusion model, the effect of the MCrAlY coatings on the formation of TCP phases in the substrate was studied, and a GOODMAN map for designing TCP-limited MCrAlY coatings can be provided.