Wyniki wyszukiwania - BazTech

1

Adsorption of hydrated Fe(OH)2+ on the kaolinite surface : A density functional theory study

Wu Hongqiang, Miao Yuqi, Long Qibang, Yan Huashan, Li Yong, Qiu Sen, Wu Hao, Zhao Guanfei, Qiu Tingsheng

Physicochemical Problems of Mineral Processing

|

2023

|

Vol. 59, iss. 6

art. no. 174415

EN

The present study employed density functional theory (DFT) to analyze the adsorption configuration and mechanism of Fe(OH)2+ on the kaolinite (001) surface. The findings demonstrated that Fe(OH)2(H2O)4+ is the main type in which hydrated Fe(OH)2+ can be found in aqueous solution. On the surface of kaolinite, Fe(OH)2(H2O)4+ will be adsorbed. There are two forms of adsorption: outer-sphere and inner-sphere coordination (monodentate/bidentate) adsorption. Fe(OH)2(H2O)4+ has a moderate propensity to adsorb on the alumina octahedral sheet of kaolinite when the outer-sphere coordination adsorption takes place. In cases of inner-sphere coordination adsorption, Fe exhibits a tendency to form monodentate adsorption compounds in conjunction with Ou atoms. Additionally, it prefers to create bidentate adsorption compounds through coordination with both Ot and Ou atoms. The adsorption mechanism analysis results show that the ionic property of Fe atom decreases after outer-sphere coordination adsorption. After inner-sphere coordination adsorption, some electrons of Fe atom are transferred to the surface O atom. The presence of electrons between the Fe and O atoms enhances the formation of bonds, hence enhancing the covalent nature of the Fe-O bond. Theoretical FT-IR (Fourier transform infrared spectroscopy) calculations show that the formation of Fe-O chemical bonds. Because of the lower adsorption energy and more chemical bonds, hydrate Fe(OH)2+ is more likely to be bidentate adsorbed on the kaolinite surface.

2

Degree of paraxiality of a multi-Gaussian beam diffracted by a circular aperture

Cheng Jinping, Xiao Yingying, Wu Hao, Ji Xiaoling, Wang Tao

Optica Applicata

|

2023

|

Vol. 53, nr 4

621--631

EN

The degree of paraxiality (DOP) of a diffracted multi-Gaussian beam is discussed. It is shown that the DOP of the multi-Gaussian beam will decrease as it is diffracted by a circular aperture, and the DOP of the diffracted multi-Gaussian beam is influenced by both the aperture radius and the characteristics of beam source. As an example, the dependence of the DOP on the aperture radius, the boundary characteristic, and the beam waist width is investigated.

3

Parameter identification approach using improved teaching and learning based optimization for hub motor considering temperature rise

Li Yong, Wang Yuan, Zhang Taohua, Hu Han, Wu Hao

Metrology and Measurement Systems

|

2023

|

Vol. 30, nr 1

99--115

EN

Temperature rise of the hub motor in distributed drive electric vehicles (DDEVs) under long-time and overload operating conditions brings parameter drift and degrades the performance of the motor. A novel online parameter identification method based on improved teaching-learning-based optimization (ITLBO) is proposed to estimate the stator resistance, 𝑑-axis inductance, 𝑞-axis inductance, and flux linkage of the hub motor with respect to temperature rise. The effect of temperature rise on the stator resistance, 𝑑-axis inductance, 𝑞-axis inductance, and magnetic flux linkage is analysed. The hub motor parameters are identified offline. The proposed ITLBO algorithm is introduced to estimate the parameters online. The Gaussian perturbation function is employed to optimize the TLBO algorithm and improve the identification speed and accuracy. The mechanisms of group learning and low-ranking elimination are established. After that, the proposed ITLBO algorithm for parameter identification is employed to identify the hub motor parameters online on the test bench. Compared with other parameter identification algorithms, both simulation and experimental results show the proposed ITLBO algorithm has rapid convergence and a higher convergence precision, by which the robustness of the algorithm is effectively verified.

4

Investigating the selectivity of calcium hypochlorite for flotation separation of chalcopyrite and pyrite pre-adsorbed collector

Yang Wenhui, Qiu Xianhui, Yan Huashan, Wu Hao, Yang Liu, Lai Ruisen, Qiu Tingsheng

Physicochemical Problems of Mineral Processing

|

2022

|

Vol. 58, iss. 4

art. no. 150703

EN

Bulk flotation is usually used in the flotation of Cu-Fe sulfide ore, and the subsequent concentrate is difficult to be separated because the minerals have adsorbed the collector. In this paper, flotation tests showed that calcium hypochlorite (Ca(ClO)2) had a stronger depression effect on pyrite pre-adsorbed sodium butyl xanthate (SBX), while having a negligible depressive effect on chalcopyrite. A copper concentrate with Cu grade of 33.32% and Cu recovery of 94.47% could be obtained from flotation tests of mixed minerals. The depression performance and mechanism of Ca(ClO)2 were studied by contact angle measurements, Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy analyses, the results suggested that Ca(ClO)2 can decomposes SBX on the pyrite surface and oxidizes the mineral surface to form hydrophilic substances, which enhances the hydrophilicity of the pyrite surface. In contrast, Ca(ClO)2 has little effect on chalcopyrite pre-adsorbed SBX, the possible depression model is discussed.

5

Analysis of neurotransmitter catecholamines and related amines in human urine and serum by chromatography and capillary electrophoresis with 1, 3, 5, 7-tetramethyl-8-(N-hydroxysuccinimidyl propionic ester)-difluoro-boradiaza-s-indacene

Cao Liwei, Wu Lizhen, Zhong Hailan, Wu Hao, Zhang Siyun, Meng Jianxin, Li Fengyu

Acta Chromatographica

|

2022

|

Vol. 34, no. 3

276--286

EN

Two sensitive and effective methods were developed for the detection of catecholamines and related biogenic amines (dopamine, epinephrine, norepinephrine, serotonin, levodopa and tyramine) using high performance liquid chromatography with fluorescence detection and capillary electrophoresis with laser-induced fluorescence detection. A BODIPY fluorescent dye, 1, 3, 5, 70-tetramethyl-8-(N-hydroxysuccinimidyl propionic ester)-difluoroboradiaza-s-indacene was used as pre-column derivatization reagent. The separation and derivatization conditions were optimized in detail. In high performance liquid chromatography with fluorescence detection method, the derivatization reaction was completed at 35 °C for 20 min. At the wavelength of λex/λem = 493 nm/513 nm, dopamine, epinephrine, norepinephrine, and levodopa derivatives achieved baseline separation within 15 min. The limits of detection (S/N = 3) were 1.0, 2.0, 5.0, and 0.5 nmol/L, respectively. In capillary electrophoresis with laser-induced fluorescence detection method, the derivatization reaction was completed at 25 °C for 20 min. Serotonin, tyramine and dopamine derivatives reached baseline separation within 10 min at the wavelength of λex = 473 nm. The limits of detection (S/N = 3) for serotonin, tyramine, and dopamine were 0.3, 0.02, and 0.2 nmol/L, respectively. The amino compounds in human serum and urine samples were detected successfully, and the recoveries were 93.3%–106.7% and 91.0%–103.1%, respectively.

6

Basic theory and optimization of gold containing antimony concentrate leaching by alkaline sulfide

Wu Hao, Feng Yali, Li Haoran, Liao Shengde, Wang Hongjun

Physicochemical Problems of Mineral Processing

|

2019

|

Vol. 55, iss. 1

248--257

EN

As sodium sulfide is easily oxidized to polysulfide and thiosulfate which have a gold leaching effect, gold would dissolve in leaching solution when extracting stibium from gold containing antimony concentrate by alkaline sulfide. Through leaching test and kinetics analysis, the decomposition regularity of sodium sulfide and leaching rate were studied under different leaching conditions. The results indicated that the gold content in antimony concentrate was 28.41g/Mg, and the content of antimony and sulfur was 36.01% and 14.04%, respectively. The main metallic minerals were native gold, arsenopyrite, stibnite, and the gangue minerals were mainly quartz. Anodic polarization curve shows reduced iron powder can increase the peak potential of the oxidation of the leaching solution and it can effectively prevent the decomposition of sodium sulfide and the dissolution of gold. Optimized stibium-extraction efficiency was achieved under the following conditions: a concentration of sodium sulfide and sodium hydroxide at 110g/dm³ and 20g/dm³, respectively; a ratio of iron powder to concentrate of 1:30; a ratio of liquid to solid of 5:1; agitation speed of 600rad/min; reaction temperature of 353.15K; and a reaction time of 3 h. Under the optimized conditions, high antimony recovery (97.35%) and low gold dissolution (1.32%) were achieved.