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Sludge biochar supported Fe(II) (Fe(II)-SBC) was successfully prepared using waste activated sludge as peroxydisulfate (PDS) activator to condition sludge for deep dewatering. The experimental results showed that Fe(II)-SBC with FeO on it could effectively active PDS to produce ${\rm SO}_4^{-\cdot }$ SO 4 − ⋅ and ${\rm HO}\cdot$ HO ⋅. The radicals could destroy the structure of sludge cells and extracellular polymeric substance (EPS), transformed the hydrophilic and tightly bound EPS into soluble-EPS, degrade partial proteins and polysaccharides and released bound water. The negatively charged groups on sludge floc were dripped off by ${\rm SO}_4^{-\cdot }$ SO 4 − ⋅ / $\; {\rm HO}\cdot$ HO ⋅ or neutralized with Fe2+, Fe3+, H+, or Fe(II)-SBC, leading to an increase in zeta potential to −2.24 mV and sludge destabilization. The residual Fe(II)-SBC served as a skeleton builder that decreased the compression coefficient of the sludge cake to 0.75. Under the combined functions, the CST and SRF were reduced by 70% and 82.7%, respectively, and Wc was reduced to 72.4%. The byproducts of Fe3+ and SO42- finally remained in sludge cake in the form of NaFeSi2O6 and CaSO4. [ABSTRACT FROM AUTHOR]

The removal of phosphorus is essential to recycling steelmaking slag in metallurgical processes. In this study, dilute nitric acid was selected as the leaching agent for dissolving steelmaking slag. The effects of the variables on leaching percentage of phosphorus were investigated. Experimental results showed that, the leaching percentages of phosphorus increase as the concentration of nitric acid increases. Increasing the liquid/solid ratio and decreasing the slag particle size increased the leaching percentages of the phosphorus. However, the temperature and stirring speed had minor effects on the dissolution of phosphorus. Diffusion through the product layer was the rate-limiting step of the leaching process, and the corresponding apparent activation energy was determined to be 1.61 kJ/mol. Based on experimental results, a semi-empirical kinetic equation was established. [ABSTRACT FROM AUTHOR]

In this work, FeSe2@CNT nanocomposite anode materials are fabricated using a convenient and efficient one-step microwave method. The FeSe2@CNT electrode exhibits superior electrochemical performance. The carbon nanotube structure effectively mitigates the severe volume change in the FeSe2@CNT electrode during continuous charge and discharge. Thus, the capacitance value of 573 F g−1 and capacitance retention of 81.9% for 3000 constant current charge and discharge cycles are achieved. In addition, the asymmetric device assembled with FeSe2@CNT as the anode and NiSe2@CNT as the cathode exhibits high Energy density (E can reach 41.32 Wh kg−1 when P is 800 W kg−1), and the device achieves 82.6% capacity retention after 3000 cycles. [ABSTRACT FROM AUTHOR]

To solve the problems of holes, noise, and texture information missing in the traditional incremental reconstruction of complex surface objects, a 3D reconstruction method of depth image fusion surface dense point clouds is proposed, and texture feature creation is combined to obtain a 3D reconstruction model that takes into account the main body and details of the reconstructed object. First, the mechanism of surface dense reconstruction based on the patch-based multiview stereo (PMVS) algorithm is analyzed. Combined with the principle of view angle selection of stereo images, surface point cloud density reconstruction is performed. Then, the depth value is optimized by the region growing method, and the optimization model is established. The depth image is fused into a dense surface, and the reconstructed part is supplemented by the depth information. Finally, the Markov random field (MRF) is introduced to describe the richness of image details, and combined with the calculating method of the area coordinate, the texture coordinates are accurately calculated to reproduce the texture details of the 3D reconstruction model. 3D reconstruction experiments are performed on multiple indoor and outdoor model surfaces, and the experimental results show that the proposed method can achieve complete and accurate reconstruction of complex surface objects. Our method provides technical support for complex surface topography detection and has industrial practical significance. [ABSTRACT FROM AUTHOR]

To clarify the parameters interaction effects and improve the forming quality of Fe-Cr alloy multilayer laser powder-fed additive manufacturing (LPF-AM) on AISI 4340 substrate, experimental research for Fe-Cr alloy multilayer LPF-AM was carried out via the response surface method (RSM). The interaction effects and evolution rules of laser energy density (E), powder feed rate (Q), and Z -axis increment (h) on minimum cladding height, deposition efficiency and surface spheroidization defects were discussed. The multiobjective particle filter resampling particle swarm optimization (MORPSO) algorithm was adopted to optimize the processing parameters. The phase transformation, grain growth, and microhardness of multilayer LPF-AM were analyzed. The results showed that the powder feed rate and Z -axis increment were found to affect the minimum cladding height and deposition efficiency, respectively. Laser energy density played an essential role in spheroidization defects. The forming quality was significantly improved based on the optimal process parameters of E = 33 J/mm2, Q = 0.5 g/s, and h = 0.8 mm. The primary and secondary remelting zones are fine equiaxed dendrites and irregular cellular structures, respectively, and the microstructure of the cladding tracks and layers showed a good metallurgical bonding. The microhardness of the cladding layer ranged from 321 ± 18 to 625 ± 24 HV0.5, and the average microhardness is twice that of the AISI 4340 substrate. [ABSTRACT FROM AUTHOR]