Stone coal enriches more elements compared to other coals, especially Vanadium (V). The content of Co is relatively low, while its environmental risk is relatively high. This study collected the stone-coal samples to investigate the enrichment characteristics and the chemical speciation in the combustion products of V and Co in stone coal at an open-pit coal mine in Ankang City, Shanxi Province, China. A simulation combustion experiment and sequential chemical extraction were conducted. Mineral composition was analyzed for raw-stone coal and its combustion products. The results showed that most of V and Co are mainly enriched in combustion products during the combustion process, the enrichment capacity of Co is higher than V. With the increase in the combustion temperature, the bioavailable chemical speciation of V in stone coal combustion products increased, while Co decreased. If the combustion products are stored without effective treatment, the surrounding environment will be polluted, and then human health might be endangered.

The naturally occurring primordial radionuclides in coals might exhibit high radioactivity, and can be exported to the surrounding environment during coal combustion. In this study, nine coal samples were collected from eastern Yunnan coal deposits, China, aiming at characterizing the overall radioactivity of some typical nuclides (i.e., 40K, 238U, 232Th, 226Ra) and assessing their ecological impact. The mean activity concentrations of 238U, 232Th, 40K and 226Ra are 63.86 (17.70–92.30 Bq· kg-1), 23.76 (11.10–37.10 Bq· kg-1), 96.84 (30.60–229.30 Bq· kg-1) and 28.09 Bq·kg-1 (3.10–61.80 Bq·kg-1), respectively. Both 238U and 232Th have high correlations with ash yield of coals, suggesting their inorganic origins. The overall environmental effect of natural radionuclides in studied coals is considered to be negligible, as assessed by related indexes (i.e., radium equivalent activity, air-adsorbed dose rate, annual effective dose, and external hazard index). However, the absorbed dose rates values are higher than the average value of global primordial radiation and the Chinese natural gamma radiation dose rate.

The acute and chronic toxicity experiments were conducted towards D. magna for five heavy metals, namely Hg, Cd, Cu, Pb and Cr, existing in single or mixture. The single results suggested that Hg was the most toxic, and then Cd, Cu, Pb and Cr in turn. The joint experiments indicated that toxicity for all mixtures were synergistic to D. magna using Toxic Units (TU s ) and Additional Index (AI). For more toxic Hg-Cd-Cu-Pb-Cr mixture and Hg-Cd mixture, toxicity enhancement index (TEI), a measurement index of the degree of joint toxicity enhancement compared to single toxicity, were 10.4 and 13.7, respectively. In addition, the copper ion strongly reduced the combined toxicity of Hg-Cd mixture, and lead ion affect slightly on the toxicity of Hg-Cd-Cu mixture, and chromium ion was lowest toxic to D. magna, but its exist made the joint toxicity of Hg-Cd-Cu-Pb mixture increased more than six times. Chronic test showed that the reproduction of D. magna was significantly inhibited compared to the ones of control group when concentration was designed at the level of water quality for fisheries in China (GB1160-89). It was proved in this research that it's unreasonable to draft the environmental standard only based on the results of single toxicological test.

No abstract

In this study, iron oxide (Fe3O4) was coated with ZrO2, and doped with three rare earth elements((Y/La/Ce), and a multi-staged rare earth doped zirconia adsorbent was prepared by using uniform design U14, Response Surface methodology, and orthogonal design, to remove As3+ and As5+ from the aqueous solution. Based on the results of TEM, EDS, XRD, FTIR, and N2-adsorption desorption test, the best molar ratio of Fe3O4:TMAOH:Zirconium butoxide:Y:La:Ce was selected as 1:12:11:1:0.02:0.08. The specific surface area and porosity was 263 m2/g, and 0.156 cm3/g, respectively. The isothermal curves and fitting equation parameters show that Langmuir model, and Redlich Peterson model fitted well. As per calculations of the Langmuir model, the highest adsorption capacities for As3+ and As5+ ions were recorded as 68.33 mg/g, 84.23 mg/g, respectively. The fitting curves and equations of the kinetic models favors the quasi second order kinetic model. Material regeneration was very effective, and even in the last cycle the regeneration capacities of both As3+ and As5+ were 75.15%, and 77.59%, respectively. Adsorption and regeneration results suggest that adsorbent has easy synthesis method, and reusable, so it can be used as a potential adsorbent for the removal of arsenic from aqueous solution.