Generation of selenium-rich wheat mutants and exploration of responsive genes for selenium accumulation.

KEY MESSAGE: Salt tolerance, selenium accumulation and expression of the responsive genes were analyzed in the wheat high selenium mutants. Selenium is an essential trace element for the human body, and its deficiency can lead to various diseases such as Keshan disease and large bone disease. Wheat, being a major staple crop, plays a crucial role in providing dietary selenium supplementation to combat this deficiency. Despite progress in understanding the molecular regulation of selenium accumulation in certain crops, the molecular mechanisms governing selenium accumulation-related gene expression in wheat plants remain poorly understood. In this study, three mutant wheat lines with elevated selenium content were identified. Under the treatment of Na2SeO3 or NaCl, the selenium-rich wheat mutants exhibited decreased sensitivity to both selenium and NaCl compared to the wild type. Additionally, there was an increase in the activities of SOD and POD, while the content of MDA decreased. Through qRT-PCR analysis, the expression of selenium-related genes was affected, revealing that some of these genes not only regulate the response of wheat to salt stress, but also play a role in the process of selenium accumulation. The transcriptome results revealed that the important genes encoding glutathione S-transferases, peroxidases, superoxide dismutases, and UDP-glucosyltransferases may function in the regulation of salt tolerance and selenium accumulation in wheat. These findings significantly contribute to the current understanding of the molecular regulation of selenium accumulation in wheat crops, while also offering novel germplasm resources for cultivating selenium-rich and salt-tolerant wheat lines.

Arsenic release pathway and the interaction principle among major species in vacuum sulfide reduction roasting of copper smelting flue dust.

The efficient release of arsenic in copper smelting flue dust (CSFD) with complicated production conditions and composition under the premise of environmental safety is difficult for the copper smelting industry. The vacuum environment is conducive to the volatilization of low-boiling arsenic compounds, which is beneficial to the physical process and chemical reaction of increasing the volume. In the present study, combined with thermodynamic calculations, the roasting process of pyrite and CSFD mixed in proportion in vacuum was simulated. Additionally, the release process of arsenic and the interaction mechanism of the main phases were performed in detail. The addition of pyrite facilitated the decomposition of stable arsenate in CSFD into volatile arsenic oxides. The results indicated that exceeding 98% of arsenic in CSFD volatilized into the condenser, while the arsenic content in the residue was reduced to 0.32% under optimal conditions. Pyrite could reduce the oxygen potential during the chemical reaction with CSFD, reacting with sulfates in CSFD to convert into sulfides and magnetic iron oxide (Fe3O4) simultaneously, and Bi2O3 would be transformed into metallic Bi. These findings are significant for developing arsenic-containing hazardous waste treatment routes and the application of innovative technical approaches.

The lead removal evolution from hazardous waste cathode ray tube funnel glass under enhancement of red mud melting and synthesizing value-added glass-ceramics via reutilization of silicate resources.

Waste CRT funnel glass (FG) is a typical hazardous waste produced by the electronics industry that contains toxic lead oxide, red mud (RM) is the first waste produced during alumina production. Both of these are extremely difficult to reuse. Here, we report a method to control FG waste, in which RM was used to enhance the removal of Pb from FG via a vacuum thermal process. The removed residual glass was utilized to create glass-ceramics. The results showed that RM can enhance the lead removal from waste CRT funnel glass by the vacuum thermal process. When 30% RM was added, the removal rate reached 98.54%. A significant mechanism of enhancing delead is investigated by a Fourier transform infrared (FTIR) spectrometer and X-ray photoelectron spectroscopy (XPS). The results showed that the -Pb-O-Si-O- network structure was broken by the free calcium ions of RM. Afterward, valuable glass-ceramics with tetragonal-KAlSi2O6 and triclinic-CaSiO3 crystals were synthesized using the residual glass. The Pb, Ba, Cr, and Cu leaching concentrations of the glass-ceramics were well below the regulatory limit (5 mg/L) of the CA-EPA, as measured by the toxicity characteristic leaching procedure (TCLP) test. Overall, the results indicated that RM enhanced the removal of lead during the vacuum thermal process. The synthesis of value-added glass-ceramics reutilized silicate resources from waste cathode ray tube (CRT) funnel glass and RM.

Direct calciothermic reduction of porous calcium titanate to porous titanium.

A metallurgical material integration concept, using porous calcium titanate (CaTiO3) as raw material, was put forward for preparation of metallic titanium powder and porous titanium by calciothermic reduction. Porous metallic titanium was prepared by calcium vapor reduction at 1273 K for 6 h with two types of interconnected pores in titanium samples. The interconnected macropores about 50-300 µm were inherited from porous CaTiO3, and the micropores about 5-40 µm were made by leaching removal of byproduct CaO in reduction products. Metallic porous titanium was fabricated in Ca-dissolved CaO-CaCl2 molten salt mixtures by self-sintering and had a good interconnectivity inside with thickness about 155 µm and the porosities of the porous titanium are 65-81%.