Correction: Effect of support on hydrogen generation over iron oxides in the chemical looping process.

[This corrects the article DOI: 10.1039/D1RA07210B.].

Effect of support on hydrogen generation over iron oxides in the chemical looping process.

Fe2O3 is recognized as an excellent oxygen carrier for its low cost and high oxygen capacity. However, pure Fe2O3 must be deposited on supports to ensure high reactivity and durability. Here, we proposed several Fe2O3-based oxygen carriers using MgAl2O4, Ce0.8Gd0.2O1.9, and Zr0.8Y0.2O1.9 as supports and investigated their performance for chemical looping hydrogen generation. The support effect on chemical looping hydrogen generation performance was evaluated, and the fundamental insights were investigated in depth. Fe2O3/Ce0.8Gd0.2O1.9 exhibited a superior performance regarding high hydrogen yield and stable trend over 20 cycles at 750 °C. However, hydrogen yield of Fe2O3/Zr0.8Y0.2O1.9 exceeded that of Fe2O3/Ce0.8Gd0.2O1.9 at higher temperatures (850 °C). Characterizations show that Ce0.8Gd0.2O1.9 exhibits the highest oxygen vacancy concentration, which significantly improves the reduction and reoxidation reactions of Fe2O3, thus leading to an enhanced hydrogen yield. However, the interaction between Fe2O3 and Ce0.8Gd0.2O1.9 contributed to the increase in Fe2+ concentration, thus decreasing the oxygen capacity during the redox cycle and contributing to the declined hydrogen yield at higher temperatures. This work highlights the potential of Ce0.8Gd0.2O1.9 to be used as an effective support for Fe2O3 at mid-temperatures. We hope that the support effect in this work can be extended to design and select more active and durable oxygen carriers.

[Spatial Distribution Study and Pollution Assessment of Pb in Soils in the Xijiang River Drainage of Guangxi].

To obtain data for the accumulation of Pb and its risk in soils in the Xijiang River drainage of Guangxi, 2594 samples were collected from nonferrous metal mining soils, farmland soils (paddy soils and dryland soils), and the background soils in the drainage area. Geostatistical analysis combined with GIS was used to study the soil spatial distribution characteristics and pollution distribution of the soil Pb content. The results showed that the Pb background value of the soil was 51.84 mg ·kg-1 in the Xijiang River Basin, and the results of the single sample T test showed that the soil background value was significantly higher than that of a previous study (22.08 mg ·kg-1) and the soil background value (20.50 mg ·kg-1) in Guangxi province. The geometric mean concentration of Pb in the mining soils, dryland soils, and paddy soils were 655.9, 116.7, and 40.63mg ·kg-1, respectively, significantly higher than that in other soils. Using GB 15618-1995 and the baseline as the limiting value, the corresponding exceedance rate of the mining soils, dryland soils, and paddy soils were 57.69%, 16.40%, and 8.92% and 54.95%, 8.09%, and 2.03%. The mining soils and farmland soils had an obvious lead accumulation trend. There was an obvious spatial autocorrelation of Pb in the soil, and the structural variation was dominant. The content of Pb in the upper reaches of the Xijiang River reached the middle and lower reaches of the Xijiang River, and the soil Pb was characterized by an obvious decrease. The accumulation of high Pb content in the upper reaches of Diaojiang River is much larger than that in the lower reaches of Diaojiang River. The content of Pb in soil samples in the Xijiang River Basin was mainly rated between mild pollution and moderate pollution, and the pollution was concentrated in the municipal administrative area and the mining activity area. The pollution of the soil in Jinchengjiang and Nandan counties was closely related to the frequent local mining activities.

[Dietary exposure assessment of antimony to inhabitants around mine contaminated areas in Nandan County in 2013-2014].

OBJECTIVE: To investigate the contents of antimony in Nandan food, and to research the effects of dietary pathways that mining surrounding usual's heavy metal intake due to mining activities. METHODS: Based on the data from weighing method and chemical analysis method, the dietary exposure level of antimony in Nandan was calculated, and the safety of antimony intake was evaluated by the TDI established by WHO. RESULTS: A total of 864 samples from 14 food categories were analyzed. The total detection rate was 97. 2%. And antimony concentrations in food ranged from not detected to 1. 750 µg/g, with median and geometric means of 0. 007 and 0. 008 µg/g, respectively. Dietary intakes of Sb by inhabitants in Nandan were below the TDI. The mainresource of antimony was meat which contributed 64. 4% and 61. 2% of the exposure. Antimony exposure to the human health risk assessmentresult show that, through diet of antimony intake, it would not cause obvious health risk to the local resident. However, the mining residents higher than the contrast areas residents, and male are apparently higher than those in female. CONCLUSION: The dietary of Sb exposure level was safe in general. However, the meat had a high risk to the residents.

[Characteristics of Heavy Metal Contents in Human Hairs of Mine Contaminated Areas in Nandan County].

Nandan county is usually called "land of nonferrous metals". In order to discuss the impact of mining activities on the health of inhabitants in Nandan county, 200 human hair samples were collected from 4 villages (Liuzhai is a uncontaminated contrast areas, Chehe, Dachang and Zhanglao are contaminated areas) of Nandan and analyzed for contents of As, Sb, Cd, Pb, Cu and Zn. The results showed that the average contents of As, Sb, Cd and Pb were 1.260, 2.161, 2.466 and 20.92 µg·g-1 in the human hair samples from contaminated areas. They were 4.0, 20, 2.1 and 1.9 times higher than those in the contrast areas, and the Sb contents in human hair of Chehe and Dachang were higher than the recommended normal range. The contents of human hair Zn showed a negative correlation with the age of people (P<0.05), and contents of human hair Cd and Pb showed a weak negative correlation with the age of people in contaminated areas (P<0.1). The independent-samples t-test showed that Cd contents in male hair were apparently higher than those in female hair (P<0.05), however, Cu and Zn contents in female hair were apparently higher than those in male hair (P<0.05), in the contaminated areas. There were positive correlations between As and Sb, Cd and Pb, as well as As and Cd (P<0.01), while other elements showed no significant correlation between pairs. It was therefore concluded that contamination from the mining activities has exposed a serious threat to human health in the mine contaminated areas in Nandan county.

[Effects of Remedies on the Remediation of Typical Pb and Zn-contaminated soil in Huanjiang, Guangxi].

Due to the collapse of the Pb/Zn tailing dam of Huanjiang, Guangxi, the farmland along Huanjiang River are strongly acidic and heavy metal-contaminated, resulting in the loss of agricultural production. To explore some remedies and the migration of heavy metals in heavy metal contaminated-soil of Huanjiang, this study investigated the effects of different types of amendments (lime, calcium magnesium phosphate, organic fertilizer, polypropylene amide) on tested soils through soil leaching test. The results showed that T1 soil was severely acidified, reducing the pH of the soil layer to clean contact, while T2, T3, T4, T5 could significantly improve the contaminated soil pH, ranging from 2.7 to 3.2, 1.6 to 2.7 respectively. Compared with T1, in the contaminated soil at 0-20 cm, T2, T3, T4, T5 could effectively activate Pb and immobilize Zn. Compared with T1, in 20-60 cm clean soil, there was no significant differences in the effect of different treatments on DTPA-Pb and DTPA-Zn (P < 0.05). Compared with T1, T4 and T5 could provide good growing conditions for plants, which might provide technical support for future measurements such as bioremediation.

Chiral resolution, determination of absolute configuration, and biological evaluation of (1,2-benzothiazin-4-yl)acetic acid enantiomers as aldose reductase inhibitors.

A novel series of (1,2-benzothiazin-4-yl)acetic acid enantiomers was prepared by chiral resolution, and their absolute configurations were determined using the PGME method. The biological evaluation of the racemate and single enantiomers has shown a remarkable difference for the aldose reductase inhibitory activity and selectivity. The (R)-(-)-enantiomer exhibited the strongest aldose reductase activity with an IC(50) value of 0.120 µM, which was 35 times more active than the S-(+)-enantiomer. Thus, the stereocenter at the C4 position of this scaffold was shown to have a major impact on the activity and selectivity.

Copper-catalyzed asymmetric synthesis and comparative aldose reductase inhibition activity of (+)/(-)-1,2-benzothiazine-1,1-dioxide acetic acid derivatives.

A copper catalyst system for the asymmetric 1,4-hydrosilylation of the α,ß-unsaturated carboxylate class was developed by which synthesis of (+)- and (-)-enantiomers of 1,2-benzothiazine-1,1-dioxide acetates has been achieved with a good yield and an excellent level of enantioselectivity. A comparative structure-activity relationship study yielded the following order of aldose reductase inhibition activity: (-)-enantiomers > racemic > (+)-enantiomers. Further, a molecular docking study suggested that the (-)-enantiomer had significant binding affinity and thus increased inhibition activity.