Adsorption thermodynamics and kinetics of N,N'-diisopropoxypropyl- N'',N'''-oxydiethylenedicarbonyl bis (thiourea) on chalcopyrite surfaces

Guangyi Liu,Jingjing Xiao,Heng Ren,Hong Zhong 한국공업화학회 2015 Journal of Industrial and Engineering Chemistry Vol.21 No.1

In this paper, a novel surfactant, N,N'-diisopropoxypropyl-N'' ,N'''-oxydiethylenedicarbonyl bis (thiourea)(DiPOPECTU) was first introduced, and its adsorption thermodynamics and kinetics on chalcopyritesurfaces were investigated. DiPOPECTU exhibited superior hydrometallurgical performances forflotation recovery of chalcopyrite, and preferred attaching onto chalcopyrite surfaces at pH 5–10. Thethermodynamic results demonstrated that the adsorption agreed well with Langmuir isotherm and itsthermodynamic parameters were DG (298 K) = 23.48 kJ mol 1, DS = 5.95 J mol 1 K 1 and DH= 25.28kJ mol 1, respectively. This inferred DiPOPECTU adsorption onto chalcopyrite was a spontaneouslyexothermic chemisorption process. The kinetic results showed that the adsorption process was wellfitted by the pseudo-second-order equation. The adsorption rate constant was 0.14 105m2 mol 1 h 1and the calculated equilibrium adsorption amount Qe (5.71 10 5 molm 2) was close to theexperimental value Qe (5.41 10 5 molm 2). The results of diffuse reflectance infrared Fourier transform(DRIFT) spectroscopy further indicated that DiPOPECTU might chemisorbed on chalcopyrite surfaces byformation of DiPOPECTU-copper complexes. The uniquely double chelate ring structures and stericorientation of DiPOPECTU on chalcopyrite surfaces would improve the hydrophobicity of chalcopyriteparticles along with superior flotation recovery.

The role of HABTC’s hydroxamate and dithiocarbamate groups in chalcopyrite flotation

Sheng Liu,Guangyi Liu,Hong Zhong,Xianglin Yang 한국공업화학회 2017 Journal of Industrial and Engineering Chemistry Vol.52 No.-

In this paper, S-[(2-hydroxyamino)-2-oxoethyl]-N,N-dibutyl-dithiocarbamate (HABTC) wasfirst synthesizedand characterized by 1H NMR, 13C NMR and FTIR. The role of HABTC’s hydroxamate anddithiocarbamate groups in chalcopyriteflotation was evaluated by micro-flotation, bench-scaleflotation,adsorption experiments, zeta potential and X-ray photoelectron spectroscopy (XPS). HABTC exhibitedexcellent affinity to chalcopyrite particles under pH 6–10 and achieved superiorflotation recovery ofcopper minerals in comparison with sodium isobutyl xanthate (SIBX). The adsorption thermodynamicsand kinetics elucidated that HABTC adsorption on to chalcopyrite surfaces was a spontaneouslyendothermic chemisorption process. Zeta potential demonstrated that HABTC might chemisorb on to thepositive sites of chalcopyrite surfaces. XPS spectra further revealed that both dithiocarbamate andhydroxamate groups of HABTC anchored on chalcopyrite surfaces through Cu(II)-hydroxamate and Cu(I)-dithiocarbamate configurations, resulting in an enhanced collecting power of HABTC to chalcopyriteparticles.

Effect of Residual Stress Relaxation by Means of Local Rapid Induction Heating on Stress Corrosion Cracking Behavior and Electrochemical Characterization of Welded Ti-6Al-4V Alloy Under Slow Strain Rate Test

Yan Liu,Shawei Tang,Guangyi Liu,Yue Sun,Jin Hu 대한금속·재료학회 2017 METALS AND MATERIALS International Vol.23 No.3

In this study, a welded Ti-6Al-4V alloy was treated by means of local rapid induction heating in order torelax the residual stress existed in the weldment. The welded samples were heat treated at the differenttemperatures. The stress corrosion cracking behavior and electrochemical characterization of the as-weldedsamples before and after the post weld heat treatment as a function of residual stress were investigated. Electrochemical impedance spectroscopy measurements of the samples under slow strain rate test wereperformed in a LiCl-methanol solution. The results demonstrated that the residual stress in the as-weldedsample was dramatically reduced after the post weld heat treatment, and the residual stress decreased withthe increase in the heat treatment temperature. The stress corrosion cracking susceptibility and electrochemicalactivity of the as-welded sample were significantly reduced after the heat treatment due to therelaxation of the residual stress, which gradually decreased with the decreasing value of the residual stressdistributed in the heat treated samples.

Separation of chalcopyrite from galena with 3-amyl-4-amino-1, 2, 4-triazole-5-thione collector: Flotation behavior and mechanism

Zhiyong Zhang,Yiming Wang,Guangyi Liu,Sheng Liu,Jun Liu,Xianglin Yang 한국공업화학회 2020 Journal of Industrial and Engineering Chemistry Vol.92 No.-

3-Amyl-4-amino-1,2,4-triazole-5-thione (AATT) reacted with Cu2+ or Pb2+ ions in aqueous solutions toform CuAATT and Pb(AATT)2 complexes and their solubility product constants were measured as 10 16.17and 10-20.60, respectively. In the moderately-alkaline media, both chalcopyrite and galena chemisorbedAATT on to their surfaces, and the adsorption amount of AATT on chalcopyrite was bigger than that ongalena, which rendered a stronger hydrophobization toward chalcopyrite. While under the high-alkalinepulp, AATT only chemisorbed on chalcopyrite, not on galena. The micro-flotationfindings indicated thatAATT was a favorable collector forflotation enrichment of chalcopyrite and galena at pH <11.0, andrealized an efficientflotation separation of chalcopyrite from galena under pH>11.5. The CuAATTcomplexwas more insoluble than Pb(AATT)2, which implied a stronger affinity of AATT toward chalcopyrite thangalena and returned their selectiveflotation separation at the high-alkaline condition.

Enhanced Production of Docosahexaenoic Acid (DHA) and Squalene in Unicellular Marine Thraustochtrid Protists

Xiuping LIU,Xingyu ZHU,Guangyi WANG 한국생물공학회 2023 한국생물공학회 학술대회 Vol.2023 No.10

A novel surfactant, N,N-diethyl-N0-cyclohexylthiourea: Synthesis, flotation and adsorption on chalcopyrite

Zhiling He,Guangyi Liu,Xianglin Yang,Wei Liu 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.37 No.-

In this paper, a novel surfactant, N,N-diethyl-N0-cyclohexylthiourea (DECHTU) was synthesized and firstintroduced as a collector for chalcopyrite flotation. The micro-flotation results demonstratedchalcopyrite with adsorbed DECHTU exhibited good hydrophobicity and was effectively concentratedby nitrogen bubbles under pH 4–8. The adsorption of DECHTU onto chalcopyrite surfaces was fitted wellby the pseudo-second-order model and Langmuir isotherm, and was a spontaneously exothermicchemisorption process. The adsorption enthalpy change, entropy change and free energy change wereDH = 31.10 kJ mol 1, DS = 6.32 J mol 1 and DG (298 K) = 29.41 kJ mol 1, respectively. The activa-tion energy of the adsorption process was 17.39 kJ mol 1. The zeta potential results implied thatDECHTU adsorbed onto chalcopyrite surfaces as its anionic species with the release of H+ ion of NH–C(55S)–N group into aqueous solutions. The XPS spectra confirmed that there existed Cu(I)–DECHTUsurface complexes on chalcopyrite surface by bonding of copper atom with the sulfur atom of DECHTU,accompanying with the reduction of cupric to cuprous.

Thiadiazole-thione surfactants: Preparation, flotation performance and adsorption mechanism to malachite

Yaoguo Huang,Guangyi Liu,Jun Liu,Xianglin Yang,Zhiyong Zhang 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.67 No.-

In this paper, novel thiadiazole-thione surfactants including 5-heptyl-1,3,4-thiadiazole-2-thione (HpSDT), 5-phenyl-1,3,4-thiadiazole-2-thione (PSDT) and 5-(2-hydroxyphenyl)-1,3,4-thiadiazole-2-thione (HPhSDT) were synthesized and originally introduced as collectors in froth flotation. Micro-flotation tests showed that HpSDT exhibited better flotation response to malachite than PSDT and HPhSDT, as well as excellent flotation selectivity against quartz. The contact angle results inferred that the hydrophobization intensity of these collectors toward malachite was in the order as HpSDT > PSDT > HPhSDT. ζ-potential recommended a chemisorption of HpSDT on malachite surfaces. FTIR deduced that cupric or cuprous atoms might bond with the S and N atoms of HpSDT to form a conjugated ring. XPS further gave an additional evidence that HpSDT-Cu(I) complexes were produced on malachite surfaces via combining surface Cu atoms with HpSDT’s N and S atoms, with reducing surface Cu(II) to Cu(I). The tighter orientation arrangement on malachite and stronger hydrophobicity rendered HpSDT to possess better flotation affinity toward malachite than PSDT and HPhSDT.

5-Heptyl-1,3,4-oxadiazole-2-thione: Synthesis and flotation mechanism to chalcopyrite

Yaoguo Huang,Guangyi Liu,Longqun Ma,Jun Liu 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.61 No.-

In this article, 5-heptyl-1,3,4-oxadiazole-2-thione (HpODT) surfactant was synthesized and originally recommended as a collector for flotation recovery of chalcopyrite, bornite and pyrite. The micro-flotation findings indicated that compared with traditional collectors such as sodium isobutyl xanthate (SIBX) and sodium hexyl xanthate (SHX), HpODT possessed superior flotation affinity to chalcopyrite and bornite, and selectivity against pyrite under alkaline circumstances. After HpODT treatment, the contact angle of chalcopyrite increased, suggesting an improved hydrophobicity of chalcopyrite surfaces. Adsorption thermodynamic and kinetic analyses suggested that chalcopyrite adsorption of HpODT was a spontaneous-endothermic chemisorption process, and the ΔH (change of enthalpy), ΔS (change of entropy), ΔG (change of free energy) and Ea (activation energy) were 21.06 kJ mol−1, 173.63 J mol−1 K−1, −30.77 kJ mol−1 (298 K) and 20.19 kJ mol−1, respectively. The results of zeta potential hinted that HpODT chemisorbed on chalcopyrite surfaces. UV–vis spectra clearly observed that HpODT selectively reacted with Cu+ or Cu2+, not with Fe2+ or Fe3+ ions. FTIR spectra inferred that HpODT–Cu surface complexes were formed on chalcopyrite by reaction of HpODT’s CNNHC(S)O group with surface copper atoms to build CuS and CuN bonds.

MTPA Trajectory Tracking Control with On‑line MRAS Parameter Identifcation for an IPMSM

Ningzhi Jin,Guangyi Li,Kai Zhou,Jinfeng Liu,Herbert Ho‑Ching Iu 대한전기학회 2019 Journal of Electrical Engineering & Technology Vol.14 No.6

The maximum torque per ampere (MTPA) control is capable of obtaining its maximal ratio of torque to current in a control system of interior permanent magnet synchronous motor (IPMSM). However, when its electrical parameters change with the actual operating conditions, the resulting MTPA trajectory will defect from the optimal one. To solve this problem, a modifed model reference adaptive system (MRAS) method is investigated for the parameter identifcation of the rotor fux linkage and the stator q-axis inductance, after a tradeof between the MTPA trajectory derivation degree with parameter change and the rank-defciency problem in the identifcation model. In this method, a full-rank estimator and its gain matrix are designed according to the Popov Hyper Stability Theorem. And the current operating point is updated using the identifed parameters in order for the real-time tracking of MTPA trajectory. Simulation and experimental results verify that the proposed method enhances remarkably the MTPA tracking control efect and the system’s torque-current characteristics for an IPMSM.

An Improved Attention-based Bidirectional LSTM Model for Cyanobacterial Bloom Prediction

Jianjun Ni,Ruping Liu,Guangyi Tang,Yingjuan Xie 제어·로봇·시스템학회 2022 International Journal of Control, Automation, and Vol.20 No.10

Cyanobacterial blooms are one of the most serious water pollution problems for freshwater lakes. The treatment of blooms requires a lot of material and financial resources, so an early accurate prediction of cyanobacterial blooms is a very important way to deal with the outbreak of them. But it is challenging to predict the cyanobacterial blooms due to the uncertainty and complexity of their growth process. To deal with this problem, an improved attention-based bidirectional long short-term memory (LSTM) model is proposed in this paper, to make multistep predictions of chlorophyll-a concentration, which is a recognized characterization of algae activity. Firstly, the convolutional neural network (CNN) is used to extract data features and spatiotemporal correlation. Secondly, the bidirectional LSTM network (BiLSTM) is used to predict the concentration of chlorophyll-a based on the extracted features. Finally, the attention mechanism is used to calculate the weights for the characteristic factors that affect the chlorophyll-a concentration. At last, some experiments are carried out based on the real monitoring data of a platform in the Taihu Lake area. Compared with the prediction results of the other four state-of-the-art deep learning methods, the results show that the proposed method in this paper has the highest prediction accuracy.