Solid-oil separation of coal tar residue to reduce polycyclic aromatic hydrocarbons via microwave-assisted extraction.

Coal tar residue (CTR) is acknowledged as hazardous industrial waste with high contents of carbon and toxic polycyclic aromatic hydrocarbons (PAHs). Microwave-assisted extraction for separating tar and residue in CTR was investigated to reduce the content of PAHs. The key operating factors such as solvent type, solvent addition amount, radiation temperature, and radiation time in the extraction process were evaluated. Results showed that extreme extraction performance in the solvent with cyclic structure was attained, and an enhancement in extraction efficiency was achieved in elevated solvent addition amount, radiation temperature, or radiation time in a certain range. The optimized conditions were determined as benzene was chosen as extractant, solvent-solid ratio of 5:1 mL/g, radiation temperature of 75 °C, and radiation time of 10 min. Relative extraction efficiency of CTR and reduction efficiency of 16 priority control PAHs were 28.70% and 92.82%, respectively. According to the characterizations of extracted residue (MCTR) and tar (MCT) under optimum experimental conditions, it is possible to convert them into value-added products (carbon materials, solid fuels, or chemicals). Solid-oil separation via microwave-assisted extraction is a safe and high-valued utilization approach for CTR.

Association between ablation technology and asymptomatic cerebral injury following atrial fibrillation ablation.

BACKGROUND: Asymptomatic cerebral injury (ACI) detected by diffusion-weighted magnetic resonance imaging (MRI) following atrial fibrillation (AF) ablation has been reported recently. The purpose of this study was to provide an overview of the incidence of ACI detected by MRI following AF ablation and to explore the association between ablation technology and ACI by systematically reviewing published trials. METHODS AND RESULTS: PubMed, Web of Science, and the Cochrane Library Databases were systematically searched for studies exploring ACI detected by MRI following AF ablation. Incidence of ACI, odds ratios, and 95% confidence intervals (CIs) were pooled. We identified 21 eligible studies. The combined ACI incidence across all studies was 15.9% (95% CI: 0.124-0.202). We also did a subgroup analysis stratified by different technologies. The incidence of ACI stratified by ablation technology was 13.0%, 27.6%, 12.5%, 17.3%, and 32.6% of the irrigated radiofrequency (RF), multielectrode-phased RF pulmonary vein ablation catheter (PVAC), cryoballoon, laser balloon, and nMARQTM groups, respectively. CONCLUSIONS: The incidence of ACI following AF ablation with PVAC was higher than with other technologies. Uninterrupted oral anticoagulant (OAC) during the procedure could lower the incidence of ACI. It seems prudent not to interrupt OACs during the procedure. In addition, intraprocedural activated clotting time was associated with ACI. Different MRI diagnostic criteria for ACI also influenced the results. To facilitate the future research, a generally accepted definition for silent cerebrovascular ischemia suitable to different kinds of MRI is needed.

Synthesis of porous carbon derived from coal tar residue via bimetallic salt activation for effective and selective adsorption of thallium(I).

As a highly toxic rare metal, the removal of thallium (Tl) from wastewater has been widely investigated, and adsorption is considered one of the most promising treatment technologies for Tl-containing contaminated water because of its cost-effectiveness, convenience, and high efficacy. In this work, coal tar residue (CTR)-based porous carbon was synthesized through K2FeO4 activation, and applied in adsorbing Tl(I). K2FeO4 could synergistically produce porosity and load iron oxide on the produced porous carbon surface because of the catalytic cracking and oxidative etching during the activation of CTR. The adsorbent was synthesized at 800 â„ƒ with a mass ratio of K2FeO4/CTR being 3 (PC3-800) showed optimal Tl(I) adsorption performance. The removal efficiency and distribution coefficient of PC3-800 were above 95 % and 104 mL/g, respectively, in a wide pH range (4-10). Furthermore, the selection and reusability of PC3-800 were favorable. The adsorption was a spontaneous, exothermic, and entropy increase process. The adsorption process was dominated by electrostatic attraction, surface complexation, and surface oxidation. The results suggested that removing Tl(I) from contaminated water via CTR-based porous carbon was feasible.

Impact of body mass index on atrial fibrillation recurrence: a meta-analysis of observational studies.

BACKGROUND: Obesity is associated with increased risk of atrial fibrillation (AF). Several trials exploring the impact of elevated body mass index (BMI) on the catheter ablation of AF have been published and yield conflicting results. We thus conducted a meta-analysis to explore the association between elevated BMI and AF recurrence in patients undergoing catheter ablation. METHODS: A systematic review and meta-analysis was performed. Relative risks (RRs) and 95% confidence intervals (CIs) were pooled. RESULTS: Six observational studies including 2,358 patients were included. Of those, four studies were prospective cohort studies, and two were retrospective studies. Elevated BMI increased the risk of AF recurrence compared to normal BMI by 31%, where the difference between the two arms was statistically significant (RR = 1.308, 95% CI: 1.036-1.651, P = 0.02). Compared to normal BMI group, the overweight group had a 27% increased risk of AF recurrence (RR = 1.270, 95% CI 0: 961-1.679, P = 0.093) and the obese group had a significantly increased risk of AF recurrence (RR = 1.378, 95% CI: 1.006-1.887, P = 0.045). When compared to the overweight group, the obese group has a 12% increased risk of AF recurrence (RR = 1.116, 95% CI: 0.866-1.438, P = 0.397). CONCLUSIONS: Elevated BMI is associated significantly with AF recurrence in patients undergoing catheter ablation. There is a graded relationship between elevated BMI and increased risk of AF recurrence.

Immobilization of hexavalent chromium in soil-plant environment using calcium silicate hydrate synthesized from coal gangue.

The presence of excessive hexavalent chromium (Cr(VI)) in the contaminated soils and plants has become a global environmental issue due to its toxicity and carcinogenicity. This work investigated the feasibility of immobilizing Cr(VI) in the soil-plant environment using calcium silicate hydrate (C-S-H) synthesized from coal gangue. The results revealed that the C-S-H amendment increased soil pH and organic matter (OM), which further promoted Cr(VI) immobilization. Results also revealed that exchangeable and carbonate bound fractions of Cr were either converted into Fe/Mn oxide and OM bound fractions of Cr or hardly released residual fraction of Cr due to C-S-H treatment. The C-S-H accelerated conversion of Cr(VI) into Cr(III) promoting plant growth and alleviating the toxic effect of Cr(VI). Cr(VI) was mainly immobilized and accumulated in the plant roots which resulted in comparatively lower Cr(VI) content in the edible part of plants. The exchangeable fraction of Cr in soil could be used as a bioavailability evaluation index of Cr(VI) in plants. In short, C-S-H was proved to be a practical and environmentally friendly amendment for in-situ immobilization of Cr(VI) contaminated soil.

The relationship between serum vitamin K concentration and coronary artery calcification in middle-aged and elderly people.

BACKGROUND: Vitamin K is involved in the formation of coronary artery calcification which is an independent predictor of coronary heart disease. This study aims to explore the association between coronary artery calcification score and serum concentrations of vitamin K1, menaquinone-4 (MK-4) and menaquinone-7 (MK-7) in middle-aged and elderly Chinese population. METHODS: A total of 116 patients who underwent CT coronary angiography were consecutively enrolled. Serum concentrations of vitamin K1, MK-4 and MK-7 were determined by high performance liquid chromatography tandem mass spectrometry. The relationships between coronary artery calcification score and serum vitamin K concentrations were analyzed. RESULTS: Significantly lower serum vitamin K1 concentration was found in the patients with CACS > 400, comparing with the other CACS categories, respectively. Log (CACS + 1) was significantly higher in MK-4 < 0.05 ng/ml group compared with MK-4 ≥ 0.05 ng/ml group [2.03(0.21, 2.58) vs 1.31(0.00, 2.19), P < 0.05]. In subjects with established coronary calcification (defined as CACS > 10), vitamin K1 was found to be an independent factor contributing to higher CACS (r = -0.288, P = 0.013). CONCLUSIONS: In this retrospective analysis, serum vitamin K1 and MK-4 concentrations were significantly lower in middle-aged and elderly cohorts with increasing calcification scores. The significant effect of vitamin K1 on CACS was only found in individuals who already had calcification. Whether the detection of circulating vitamin K in patients with preexisting coronary calcification could guide vitamin K supplementation needs further exploration.

Critical risk analysis of metals toxicity in wastewater irrigated soil and crops: a study of a semi-arid developing region.

Toxic elemental exposure through consumption of contaminated crops is becoming a serious concern for human health. Present study is based on the environment and health risk assessment of wastewater irrigated soil and crops in a semi-arid region Faisalabad, Pakistan. The concentrations of potentially toxic elements (Cu, Cr, Mn, Fe, Pb, Zn, Ni) were analysed by atomic absorption spectrometer in five different crops (Corn, rice, wheat, sugarcane and millet), while, their topsoil's and multi targeted risks analysis were assessed. Results showed, the mean values of Pb and Zn were higher in crop than Food and Agriculture Organization guidelines for food additives and contaminants. A strong positive correlation was found among wastewater and crop's toxic metals (r2 values in Cu, Zn, Pb, Ni and Cr were 0.913, 0.804, 0.752, 0.694, 0.587 respectively). Whereas, a strong correlation was also found among soil and wastewater lead (r2 = 0.639). The calculations of Nemerow Integrated Pollution Index (NIPI) showed the soil samples maximum pollution limit (NIPI > 3) and Potential Ecological Risk Index (PERI) was found to be higher than maximum limit (PERI > 600) for all samples. While, for non-carcinogenic risk, Hazard Index (HI) values in adult were near threshold (HI > 1) for all crop samples. In children, the HI values for Corn, Rice and Wheat were above threshold limit and for Sugarcane and Millet, these were near to threshold. Cancer risk values for Cr found higher than safe limit (1 × 10-6) in adult and children for crop samples. Crop irrigation by wastewater irrigation is a prominent alternative option for water scarce countries, however prior testing and treatment of such wastewater streams must be employed to minimize the adverse impacts on human health and environment.

Health effects of arsenic, fluorine, and selenium from indoor burning of Chinese coal.

China's economy has developed rapidly in the last two decades, leading to an increase in energy consumption and consequently emissions from energy generation. Coal is a primary energy source in China because of its abundance and will continue to be used in the future. The dominance of coal in energy production is expected to result in increasing levels of exposure to environmental pollution in China. Toxic trace elements emitted during coal combustion are the main sources of indoor air pollution. They are released into the atmosphere mainly in the forms of fine ash and vapors and have the potential to adversely affect human health. Those trace elements, which volatilize during combustion, are hazardous air pollutants (HAPs) and are particularly rich in Chinese coals. Among the HAPs, arsenic (As), fluorine (F), and selenium (Se) have already been identified as pollutants that can induce severe health problems. In this review, the geochemical characteristics of As, F, and Se, including their concentration, distribution, and mode of occurrences in Chinese coal, are documented and discussed. Our investigations have confirmed the current As- and F-induced epidemics in Guizhou (Southwest China) and Se epidemic in Hubei (Northeast China). In this study, diagnostic symptoms of arseniasis, fluorosis, and selenosis are also illustrated.

Mobility behavior and environmental implications of trace elements associated with coal gangue: a case study at the Huainan Coalfield in China.

The potential environmental hazards posed by trace elements have assumed serious proportions due to their toxicity, bioavailability and geochemical behavior. The toxicity and mobility of trace elements in coal gangue is dependent on the elements' chemical properties, therefore, the quantification of the different forms of trace elements is more significant than the estimation of their total concentrations. In this study, the mobility behavior of trace elements in coal gangue from the Huainan Coalfield was studied to evaluate the potential eco-toxicity of the trace elements. Sequential extraction was employed to analyze the fractionation behavior of trace elements in coal gangue. The selected trace elements (As, Co, Cr, Cu, Mn, Ni, Se, Sn, V and Zn) are predominantly found in silicate-bound, sulfide-bound and carbonate-bound fractions. The correlation of the element concentration with ash yield, aluminum, calcium and iron-sulfur indicates that As, Co, Cu, Ni, Se and Zn in coal gangue are mainly associated with sulfide minerals, which could release from coal gangue easily and can disperse into the environment as a result of long-term natural weathering. The Risk Assessment Code reveals that the trace elements (Mn, Cr, Se, Ni, Zn, As and Cu) can pose serious environmental risks to the ecosystem. The fractionation profiles of other elements (Co, Sn and V) indicate no risk or low risk to the environment.