The increasing threat of chloride ions (Cl−) has led researchers to explore efficient removal technologies. Sewage treatment with a double-layer hydroxide/oxide (LDH/LDO) is receiving increasing attention. In this work, Mg-Al LDO adsorbents were produced by the calcination of the Mg-Al LDH precursor, which was constituted by improved coprecipitation. The influence of calcination temperature, calcination time, adsorbent dosage, Cl− initial concentration, contact time, and adsorption temperature on Cl− elimination was investigated systematically. The experimental results showed that a better porous structure endowed the Mg-Al LDO with outstanding adsorption properties for Cl−. The adsorption process was well matched to the pseudo-second-order kinetics model and the Freundlich model. Under optimal conditions, more than 97% of the Cl− could be eliminated. Moreover, the removal efficiency was greater than 90% even after 11 adsorption–desorption cycles. It was found that the electrostatic interaction between Cl− and the positively charged Mg-Al LDO laminate, coupled with the reconstruction of the layer structure, was what dominated the Cl− removal process.
Molecular force plays an important role in the interaction between collector and minerals, which directly reflects the intrinsic reason for the selectivity and collection of the collector to minerals. In this work, the interaction forces between sodium oleate (NaOL) and minerals (kaolinite and diaspore) were directly characterized by atomic force microscopy (AFM) combined with EDLVO theory. The results show that after interacting with NaOL, the zeta potentials of kaolinite and diaspore were more negative, and the hydrophobicity of minerals increased. EDLVO calculation results indicate that electrostatic repulsion dominated the interaction forces between mineral particles, and the van der Waals interaction energy, electrostatic interaction energy, and hydrophobic interaction energy increased after NaOL treatment. AFM measurements show that the NaOL collector increased the attraction force of diaspore-diaspore and kaolinite-kaolinite particles, and the increase in attraction force for diaspore-diaspore particles was larger than in kaolinite particles, which was consistent with the EDLVO results. The adhesion force between the NaOL collector and the diaspore surface was larger than in kaolinite, confirming the fact that NaOL had better collection and selectivity for diaspore than kaolinite. This work improves understanding of the interaction mechanisms between NaOL collector, diaspore, and kaolinite minerals.
The flexible grasp of automatic welding technology is very important for the production of electronic products such as integrated circuit board, and the most critical step is to accurately control the temperature of the welding area. This paper will establish the mechanism model of the influence of the temperature of each temperature zone of the reflow furnace and the speed of the conveyor belt on the temperature of the welding area through the relevant thermodynamic theory, so as to help the relevant electronic product manufacturers to accurately control the temperature of the welding area. The mechanism model of temperature change in the center of welding area is established, and the heat transfer process is divided into three steps. Firstly, according to the temperature field of the air in the furnace, the air temperature corresponding to the gap in the small temperature zone is determined, and then the heat convection process between the air temperature in the furnace and the surface of the welding area is described by using Newton’s cooling law. Finally, Fourier law is used to study the heat conduction process in the welding area.
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