Wide-field mid-infrared hyperspectral imaging beyond video rate.

Mid-infrared hyperspectral imaging has become an indispensable tool to spatially resolve chemical information in a wide variety of samples. However, acquiring three-dimensional data cubes is typically time-consuming due to the limited speed of raster scanning or wavelength tuning, which impedes real-time visualization with high spatial definition across broad spectral bands. Here, we devise and implement a high-speed, wide-field mid-infrared hyperspectral imaging system relying on broadband parametric upconversion of high-brightness supercontinuum illumination at the Fourier plane. The upconverted replica is spectrally decomposed by a rapid acousto-optic tunable filter, which records high-definition monochromatic images at a frame rate of 10 kHz based on a megapixel silicon camera. Consequently, the hyperspectral imager allows us to acquire 100 spectral bands over 2600-4085 cm-1 in 10 ms, corresponding to a refreshing rate of 100 Hz. Moreover, the angular dependence of phase matching in the image upconversion is leveraged to realize snapshot operation with spatial multiplexing for multiple spectral channels, which may further boost the spectral imaging rate. The high acquisition rate, wide-field operation, and broadband spectral coverage could open new possibilities for high-throughput characterization of transient processes in material and life sciences.

Aroma Compound Changes in the Jiangxiangxing Baijiu Solid-State Distillation Process: Description, Kinetic Characters and Cut Point Selection.

Solid-state distillation is a distinctive process for extracting the baijiu aroma compounds that determine the flavor character of baijiu. In this study, the changes in various chemical properties of the aroma compounds in three classical Jiangxiangxing baijiu fermented grain distillation processes were analyzed. The changes in the aroma compounds in the instantaneous distillates were quantified and correlation analyzes were conducted. The results showed that the effect of the aroma compounds was greater than the differences between the fermented grains. Eleven representative aroma compounds were selected to develop the kinetic models describing two opposing changes. For the regulation of the Jiangxiangxing baijiu aroma compounds, their recovery rates were calculated using a kinetic model. A comprehensive comparison of the recovery rates of the characteristic aroma and other aroma compounds at different cut-off values revealed that the optimum recovery rate of the characteristic aroma of Jiangxiangxing baijiu 2,3,5,6-tetramethylpyrazine was 14.53% at cut-off values of 3.9 and 19.8 min. In this study, representative changes in the aroma compounds and the selection of cut-off values to regulate the baijiu distillation aroma were proposed.

Different roles of FeS and FeS2 on magnetic FeSx for the selective adsorption of Hg2+ from waste acids in smelters: Reaction mechanism, kinetics, and structure-activity relationship.

Magnetic FeSx was developed as a high-performance sorbent for selectively adsorbing Hg2+ from waste acids in smelters. However, further improvement of its ability for Hg2+ adsorption was extremely restricted due to the lack of reaction mechanisms and structure-activity relationships. In this study, the roles of FeS and FeS2 on magnetic FeSx for Hg2+ adsorption were investigated with alternate adsorption of Hg2+ without/with Cl-. The structure-activity relationship of magnetic FeSx for Hg2+ adsorption and the negative effect of acid erosion were elucidated using kinetic analysis. FeS can react with Hg2+ with 1:1 stoichiometric ratio to form HgS, while FeS2 can react with Hg2+ in the presence of Cl- with novel 1:3 stoichiometric ratio to form Hg3S2Cl2. The rate of magnetic FeSx for Hg2+ adsorption was related to the instantaneous amounts of FeS and threefold FeS2 on magnetic FeSx and the amount of Hg2+ adsorbed. Meanwhile, its capacity for Hg2+ adsorption was related to the initial sum of FeS amount and threefold FeS2 amount on the surface and their ratios by acid erosion. Then, magnetic FeSx-400 was devised with adsorption rate of 2.12 mg g-1 min-1 and capacity of 1092 mg g-1 to recover Hg2+ from waste acids for centralized control.

Fluorinated magnetic porous carbons for dispersive solid-phase extraction of perfluorinated compounds.

Novel magnetic and fluorinated porous carbons (M-FPCs) with high fluorine content, large pore volume and specific surface area were first prepared by carbonizing and further fluorinating Fe-Zr bimetal-organic frameworks. The M-FPCs exhibit excellent adsorption performance toward perfluorinated compounds (PFCs), and the maximal adsorption capacity ranges from 518.1 to 919.3 mg g-1 for various PFCs. Based on this property, an environmental analytical method of dispersive solid-phase extraction (DSPE) using M-FPCs as adsorbents coupled with ultra-high-performance liquid chromatography-mass spectrometry (UPLC-MS) was developed for the detection of trace PFCs. The linear range was as wide as 10-200 ng L-1, and low limit of detection (0.02-0.16 ng L-1) and good precision (relative standard deviation less than 6.11% for intra-day and inter-day) were achieved. This method was applied to the detection of trace PFCs in environmental water and soil samples with satisfactory results.

Selective removal of Hg2+ from acidic wastewaters using sulfureted Fe2TiO5: Underlying mechanism and its application as a regenerable sorbent for recovering Hg from waste acids of smelters.

The selective removal of Hg2+ from waste acids containing high concentrations of other metal cations, such as Cu2+, Zn2+, and Cd2+, which are discharged from nonferrous metal smelting industries, is in great demand. Herein, sulfureted Fe2TiO5 was developed as a regenerable magnetic sorbent to recover Hg2+ from waste acids for centralized control. Sulfureted Fe2TiO5 exhibited an excellent ability for Hg2+ removal with the capacity of 292-317 mg g-1 and the rate of 49.5-57.6 mg g-1 h-1 at pH=2-4. Meanwhile, it exhibited an excellent selectivity for Hg2+ removal that not only the coexisting Cu2+, Zn2+, and Cd2+ can scarcely be adsorbed but also Hg2+ adsorption was hardly inhibited. The mechanism and kinetic studies indicated that the Fe2+ in the FeS2 coated on sulfureted Fe2TiO5 was exchanged with Hg2+ adsorbed at a Fe2+ to Hg2+ mole ratio of 1:2. Meanwhile, most of the Hg2+ removed by sulfureted Fe2TiO5 can be thermally desorbed primarily as ultra-high concentrations of gaseous Hg0, which can finally be recovered as liquid Hg0 for centralized control in combination with existing Hg0-recovery devices in smelters. Moreover, the spent sulfureted Fe2TiO5 could be regenerated for duty-cycle operations with re-sulfuration without a remarkable degradation of the Hg2+-removal performance. Therefore, Hg2+ recovery using sulfureted Fe2TiO5 may be a promising, low-cost, and environmentally friendly technology for the centralized control of Hg2+ in waste acids discharged from smelters.

Safe disposal of deactivated commercial selective catalytic reduction catalyst (V2O5-MoO3/TiO2) as a low-cost and regenerable sorbent to recover gaseous elemental mercury in smelting flue gas.

The reduction of Hg emissions from non-ferrous metal smelting was proposed in the Minamata Convention. Regenerable sulfureted MoO3/TiO2, which displayed excellent performance in capturing gaseous Hg0, was once developed by us to recover gaseous Hg0 in smelting flue gas (SFG) for centralized control. Recently, a large amount of spent commercial selective catalytic reduction catalysts (for example V2O5-MoO3/TiO2) mostly deactivated by CaSO4 was formed, creating a need for their safe disposal. As the main constituent of deactivated V2O5-MoO3/TiO2 is MoO3/TiO2, deactivated V2O5-MoO3/TiO2 was sulfureted to capture gaseous Hg0 from SFG for its safe disposal and the effects of V2O5 and CaSO4 on Hg0 adsorption onto sulfureted MoO3/TiO2 were investigated. Although the capturing capacity of sulfureted MoO3/TiO2 moderately decreased after the impregnation of V2O5 and CaSO4, sulfureted deactivated V2O5-MoO3/TiO2 still displayed excellent performance and reproducibility in gaseous Hg0 capture. Meanwhile, the cost performance of sulfureted deactivated V2O5-MoO3/TiO2 for Hg0 capture was outstanding as deactivated V2O5-MoO3/TiO2 needs to be safely disposed. Therefore, deactivated V2O5-MoO3/TiO2 can be sulfureted as a regenerable and low-cost sorbent that is effective in recovering gaseous Hg0 from SFG, as well as being a cost-effective and environmentally friendly method for the safe disposal of spent V2O5-MoO3/TiO2.

Acceleration of Hg0 Adsorption onto Natural Sphalerite by Cu2+ Activation during Flotation: Mechanism and Applications in Hg0 Recovery.

The rate of gaseous Hg0 adsorption onto natural sphalerite increased by approximately 1.9-7.7 times after Cu2+ activation during flotation of the natural sphalerite to remove impurities. Via a new pathway involving CuS, physically adsorbed Hg0 was oxidized by CuS to HgS on natural sphalerite after Cu2+ activation. In a similar intrinsic ZnS pathway, physically adsorbed Hg0 was oxidized by ZnS to HgS. The rate of the CuS pathway for Hg0 capture was generally significantly larger than that of the intrinsic ZnS pathway. Thus, Hg0 adsorption onto natural sphalerite was notably accelerated after Cu2+ activation. However, the kinetic analysis indicated that the capacity of natural sphalerite for Hg0 capture did not vary. Because the properties of the activated sphalerite for Zn smelting were barely degraded after Hg0 capture, the spent activated sphalerite for Hg0 capture can be reused for Zn smelting. Moreover, most of the gaseous Hg0 captured by activated sphalerite can be recovered eventually as liquid Hg0 in the condenser unit of Zn smelters. Thus, Hg0 recovery by activated sphalerite is a cost-effective and environmentally friendly technology to recover Hg0 from Zn smelting flue gas, thus replacing the complex and dangerous Boliden-Norzink process.