Zhifang Gao

A Novel Conversion of Ti-Bearing Blast-Furnace Slag into Water Splitting Photocatalyst with Visible-Light-Response

A novel visible-light-response photocatalyst was prepared through the heat treatment of Ti-bearing blast-furnace slag with sodium nitrate and subsequently leaching processes in which most of the SiO2, Al2O3, and MgO in Ti-slag (TS) have been separated. The photocatalytic activity of the TTS was studied by observing the evolution of H2 under the UV–Vis and visible light. Compared with the TS and commercial perovskite CaTiO3, the sample prepared exhibited an exclusive visible-light-response activity and enhanced H2 evolution.

Effect of Cu substitution on structures and electrochemical properties of Li[NiCo1−xCuxMn]1/3O2 as cathode materials for lithium ion batteries

Copper ions are one of the major associated metal ions present in the precursors of the synthesis of Li[NiCoMn]1/3O2 from the recovery of spent Li-ion batteries by wet chemical processes. To evaluate the feasibility of reusing Cu(2+) as a favourable dopant in Li[NiCoMn]1/3O2 instead of as usual removing it as an undesirable impurity, the effect of Cu-doping on the electrochemical behaviour of Li[NiCoMn]1/3O2 is investigated in this work. Li[NiCo1-xCuxMn]1/3O2 (x = 0, 0.02, 0.04, 0.06 and 0.08) is synthesized through two steps, roasting the precursors obtained from carbonate co-precipitation, and their structures and electrochemical performances are systemically investigated. The results indicate that substitution of Co with Cu was successfully achieved without any detectable second phases. The initial discharge capacity of Li[NiCo1-xCuxMn]1/3O2 gradually dropped with an increase of x but the rate property and capacity retention were remarkably enhanced. In particular, the capacity retention of the Li[NiCo0.94Cu0.06Mn]1/3O2 sample reached 95.87% within 50 cycles at a current density of 160 mA g(-1). CV and EIS revealed that such improvements are ascribed to a higher Li(+) diffusion coefficient and lower charge-transfer resistance derived from Cu(2+) doping. The results suggest that Cu can be used as a beneficial dopant to partially substitute Co in synthesizing Li[NiCoMn]1/3O2 from spent LIBs instead of having to remove it as an impurity.

Co-precipitation behaviour of titanium-containing silicate solution

The co-precipitation behaviour of a simulated Al2(SO4)3-TiOSO4-Na2SiO3 solution that imitated the lixivium of Ti-bearing blast furnace slag (Ti-slag) leached by sulphuric acid was investigated in this study. Various chemical analyses were employed to study the selective precipitation of multiple target components. Based on the high-added-value applications of Ti-slag, a new method was developed to prepare aluminium titanate composites from titanium-containing silicates. The findings demonstrate that the onsets of Ti and Al precipitation occur at pH values of 3.5 and 5.0, respectively, followed by Si precipitation. The particle sizes of the co-precipitates were greatly influenced by the precipitants, pH and the initial Al/Ti mole ratio. The results also show that the precipitation ratio of Ti, Al and Si generally increases with the pH and temperature, regardless of the Al/Ti mole ratio. The Si-O-Al, Ti-O-Al, and Ti-O-Si bonds that were formed were dependent on the pH and the initial Al/Ti mole ratio. There was a synthesis path for β-Al2TiO5 (AT) from the solid-state reaction between rutile and α-Al2O3 at 1362.5°C. The AT composites were successfully prepared by sintering the co-precipitates at 1450°C, which exhibited good thermal stability as estimated by the XRD measurements of the sample annealed at 1200°C for 4 hours.

Study on Fractal Characteristics of Particle Size Distribution Function for Modified-Brown Coal

Particle size distributions (PSDs) are often rendered as cumulative functions, either as number of particles larger than a certain diameter, or as mass smaller than a certain diameter. According to the application status of low rank brown coals of Inner Mongolia, the fractal characteristics of particle size distribution function of raw brown coals and modified-brown coals were analyzed in the paper. The grain size analysis and microstructure analysis of coal samples were measured by the Euro-American gram LS-C (1) type laser Particle analytical instrument, Fourier infrared spectrum (FRIT) and scanning electron microscope (SEM), respectively. The results of the study indicate that raw brown coals and modified-brown coals have fractal feature by using the mathematical model of fractal characteristics of particle size distribution function based on fractal theory. The paper provides the fractal dimensions of modified-brown coals increased with the rank of coal. Thus fractal dimensions can be used as an evaluation index of coal rank providing theoretical basis and distinguish basis for a further study on properties of modified-brown coals.