Preparation and optimization of the environmental dust suppressant with agricultural waste straw

Ecological and health risk assessment of heavy metals in agricultural soils from northern China

Soil pollution by heavy metals can cause continuing damage to ecosystems and the human body. In this study, we collected nine fresh topsoil samples and 18 maize samples (including nine leaf samples and nine corn samples) from agricultural soils in the Baiyin mining areas. The results showed that the order of heavy metal concentrations (mg/kg) in agricultural soils was as follows: Zn (377.40) > Pb (125.06) > Cu (75.06) > Ni (28.29) > Cd (5.46) > Hg (0.37). Cd, Cu, Zn, and Pb exceeded the Chinese risk limit for agricultural soil pollution. The average the pollution load index (4.39) was greater than 3, indicating a heavy contamination level. The element that contributed the most to contamination and high ecological risk in soil was Cd. Principal component analysis (PCA) and Pearson's correlation analysis indicated that the sources of Ni, Cd, Cu, and Zn in the soil were primarily mixed, involving both industrial and agricultural activities, whereas the sources of Hg and Pb included both industrial and transportation activities. Adults and children are not likely to experience non-carcinogenic impacts from the soil in this region. Nonetheless, it was important to be aware of the elevated cancer risk presented by Cd, Pb, and especially Ni. The exceedance rates of Cd and Pb in corn were 66.67% and 33.3%, respectively. The results of this research provide data to improve soil protection, human health monitoring, and crop management in the Baiyin district.

Review and prospects of mining chemical dust suppressant: classification and mechanisms

Coal mine pollution is a serious threat to the mine safe production and occupational health of miners. Chemical dust suppression can effectively reduce the concentration of coal dust and suppress the re-entrainment of dust. This paper discusses the research progress of three kinds of traditional dust suppressants: the wetting-type, cohesive type, and condensed type. In order to meet dust suppression and environmental protection requirements, 7 kinds of new type dust suppressants, such as compound, ecological environmental protection, polymer, functional, microbes, and enzymes, have been developed by the predecessors. And all kinds of dust suppressant mechanism and main performance index have been summarized. Through the analysis of the research results from 1985 to 2021, it is found that the compound and environment-friendly dust suppressants have gradually become the research focus in this field, accounting for 17.93% and 26.21% of the total number of achievements. In the recent 5 years, new materials, such as microbe suppressant, urease suppressant, and nanomaterials, have gradually emerged. Because of their natural and environmental protection characteristics, it could be predicted that they will become the future development trend in this field. However, there are still some problems to be improved, such as expensive price and complex preparation technology.

Experimental study on coal dust wettability strengthened by surface active ionic liquids

The water wettability of coal dust was very important for dust control when using water-based dust suppressant materials. The coal dust wettability strengthened by surface active ionic liquid was studied in this paper. The surface activity of ten ionic liquids with different anions Cl^-, Br^-, [BF₄]^-, [NTf₂]^- and cations [HOEtMIm]⁺, [C_nmim]⁺ (n = 4, 12, 14, 16) was studied by surface tension test. The water wettability of raw coal dust can be improved individually by adding ionic liquid to water or pre-treating coal dust by ionic liquids. The wettability of lignite was improved little, but that of bituminous coal and anthracite were improved much. The dual strengthened effects of ionic liquids on coal dust wettability were studied by the wetting results between ionic liquids solutions and ionic liquid-treated coal samples. The wettability of lignite can be strengthened under the combined action of [HOEtMIm][NTf₂] and [C₁₂MIm]Br, while other dual effects were not satisfactory. All ionic liquids combination had strengthened effects on the wettability of bituminous coal and anthracite, especially the [C₁₂MIm]Br treatment and [C₁₂MIm]Br solutions together had the best dual effects. The functional groups results indicated that the hydrophilic oxygen-containing functional groups in treated coal samples increased, the hydrophobic aliphatic hydrocarbon functional groups decreased and part of ionic liquids were adsorbed on the coal surface. These changes together enhanced the wettability of coal with high coalification degrees.