Search

The wastes network system exploration in metallurgical process imposes of great significance for advancing green circular economy in steel plant. This paper originally proposes a closed-circulating CO 2 sequestering process for wastes appreciation and harmless disposal, and the effect of two circulation strategy, i.e. Slag circulation strategy and cold-rolling waste water(CRW) circulation strategy, on the CO 2 uptake efficiency, carbonation degree and desalination rate were systemically discussed. Then, their kinetics are analyzed by model and molecular simulation in detail, respectively. In addition, the energy consumption and the cost are simulated for comprehensively evaluating its superiority. The experimental and molecular simulation results all show that the peak values for both strategies could be achieved when circulation times is in the range of three to five. CRW circulation strategy has a better CO 2 uptake efficiency than slag circulation strategy, the CO 2 uptake efficiency is about 487kgCO 2 /tslag and corresponding desalination rate is 48.9%, when CRW is circulated for five times at 60 °C and 20 L/g for 90 min. Adopting CRW circulation strategy, the CO 2 sequestration efficiency is averagely doubled comparing to previous results. 129%-183% energy consumption and 35.6% cost would be reduced, which represents that the proposed routine is economical to step forward to industrial application., Competing Interests: Declaration of competing interest The authors declare no conflict of interest., (Copyright © 2020 Elsevier B.V. All rights reserved.)

The exposure to ambient fine particulate matter (PM 2.5 ) can induce oxidative stress, contributing to global burden of diseases. The evaluation of the oxidative potential (OP) of PM 2.5 is thus critical for the health risk assessment. We collected ambient PM 2.5 samples in Hangzhou city, China for four consecutive quarters in the year 2017 and investigated the oxidation property of PM 2.5 components by the dithiothreitol (DTT) assay. The annual mean of ambient PM 2.5 mass concentrations in 2017 was 63.05 μg m -3 (median: 57.34, range: 6.67-214.33 μg m -3 ) with the significant seasonal variations ranking as winter > spring > summer > autumn. Secondary inorganic aerosol (SIA) species including SO 4 2- , NO 3 - and NH 4 + totally account for >50% of PM 2.5 mass. The annual mean volume-normalized DTT activity (DTTv) showed a relatively high value of 0.62 nmol/min/m 3 (median: 0.62, range: 0.11-1.66 nmol/min/m 3 ) and DTTv of four seasons was roughly at the same level, indicating a high annual exposure level of ambient PM 2.5 . SIA species were correlated well with the corresponding DTTv and showed significant diurnal variations with strong or moderate correlations at day and weak correlations at night, suggesting strong secondary formation in daytime with contribution to the particulate OP. The annual mean mass-normalized DTT activity (DTTm) had a relatively low value of 6.39 pmol/min/μg (median: 5.63, range: 1.99-22.70 pmol/min/μg), indicating low intrinsic oxidative toxicity. The DTTm of four seasons ranked as autumn > winter > spring > summer, indicating seasonal variations of the DTT-active components. The PM 2.5 mass concentration is more related to exposure levels than intrinsic properties of components, while OP is determined by the components rather than PM 2.5 mass concentration. Our results provide an insight into reactive oxygen species-induced health risk of PM 2.5 exposure and decision for subsequent emission control., (Copyright © 2018 Elsevier B.V. All rights reserved.)