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Abstract Industrial experiments were conducted to investigate the differences in the porosity alleviation between the multi-roll and single-roll reduction modes during continuous casting and develop a simulation model of the porosity closure. The experimental results revealed that heavy reduction and a high solid fraction were beneficial to the porosity alleviation in billets. The simulation results showed that the large plastic strain along the thickness direction (PE22) at the center region caused by the heavy reduction contributed to the porosity closure. The PE22 at the center region of the billet between the single-roll and the multi-roll reduction mode was little different for the same reduction amounts and reduction positions. The reduction efficiency was high at the position of the low solid fraction, which contributed to porosity closure. Since most areas of porosities were formed at the center region of the billet at a high solid fraction, the reduction prior to the formation of the porosities had little effect on the porosity alleviation. The single-roll reduction mode had a better effect on the porosity alleviation than the multi-roll reduction mode because the solid fraction was higher for the single-roll reduction mode. The experimental results are mostly in agreement with the simulation results. [ABSTRACT FROM AUTHOR]

We report the first example of vinylene-linked covalent organic framework (Tp-TMT) with enhanced uranium adsorption through combined selective ligand binding, chemical reduction and photocatalytic reduction. The dense hydroxyl functional groups on the Tp-TMT framework had good selectivity and excellent chemical reduction performance for U(VI). Meanwhile, the synergistic effect of hydroxyl groups and triazine unit significantly enhanced the photocatalytic reduction activity. Thus Tp-TMT exhibited incredible adsorption kinetics and capacity for uranium. [Display omitted] • COFs effectively capture uranium through three coordinated mechanisms. • Tp-TMT has excellent visible light conversion efficiency and low band gap. • Tp-TMT enhances uranium adsorption through selective ligand binding and reduction. • Tp-TMT exhibits incredible adsorption kinetics and capacity for uranium. So far, it remains a challenge to synthesize uranium adsorbents with robust stability, high adsorption capacity, excellent photocatalytic activity and easy regeneration. Herein, we report the first example of vinylene-linked covalent organic framework (Tp-TMT) with enhanced uranium adsorption through combined selective ligand binding, chemical reduction and photocatalytic reduction. The unique structure and excellent photocatalytic activity of Tp-TMT make it very suitable for photo-enhanced uranium adsorption through three synergistic mechanisms, thus exhibiting an outstanding uranium adsorption capacity (2362.4 mg g−1). In the dark, a large number of hydroxyl groups in the Tp-TMT framework serve as selective binding sites for uranium, and reduce part of U(VI) to U(IV), thereby greatly improving the adsorption capacity. Meanwhile, the synergistic effect of the triazine units and hydroxyl groups in the highly conjugated framework greatly decreases the optical band gap of Tp-TMT, and an additional U(VI) photocatalytic reduction process can occur under light irradiation, further increasing the adsorption kinetics and capacity. This work explored the structural and functional design of covalent organic frameworks for the adsorption and reduction of uranium in nuclear industry wastewater. [ABSTRACT FROM AUTHOR]