Heavy metal characteristics of vegetables and their soils in Foshan City

Investigation of the vegetable garden soil in Foshan City 4 kinds of heavy metals Cu, Pb, Zn and Cd in the total and different forms of content, while also investigating a variety of vegetables and edible part of the Cd content. The results show that, Foshan City, the heavy metal content in vegetable field exceed the national and the background value of Guangdong Province, the pollution index to the maximum Cd, Cu, followed by, Cd elements of the highest validity coefficients. Foshan City, edible part of vegetables found excessive Cd, leafy soil Cd content and Cd the full amount of exchangeable manganese content and the amount of state showed a significant positive correlation. The state of heavy metal content of vegetable soil in Foshan city was investigated. The total content and available content of 4 heavy metal elements (Cd, Pb, Zn, and Cu) were analyzed and measured. The result indicated that the heavy metal content of vegetable soil in Foshan city was greater than the average in other areas throughout Guangdong Province or even the whole country. The valid coefficient of Cd element was the greatest. The content of Cd in vegetables was greater than the state vegetable sanitation standard. In different kinds of vegetables, the content of Cd in leaf-vegetable had very significant correlation with the content of different sort Cd in soil. which indicated that the content of Cd in vegetables was affected by the content of Cd in soil

Study on Low Temperature Oxidation Characteristics of Oil Shale Based on Temperature Programmed System

Oil shale is a kind of high-combustion heat mineral, and its oxidation in mining and storage are worth studying. To investigate the low-temperature oxidation characteristics of oil shale, the temperature, CO, alkane and alkene gases were analyzed using a temperature-programmed device. The results showed that the temperature of oil shale underwent three oxidation stages, namely a slow low-temperature oxidation stage, a rapid temperature-increasing oxidation stage, and a steady temperature-increasing stage. The higher the air supply rate is, the higher the crossing point temperature is. Similar to coal, CO also underwent three stages, namely a slow low-temperature oxidation stage, a rapid oxidation stage, and a steady increase stage. However, unlike coal, alkane and alkene gases produced by oil shale underwent four stages. They all had a concentration reduction stage with the maximum drop of 24.20%. Statistical classification of inflection temperature of various gases as their concentrations change showed that the temperature of 140 °C is the key temperature for group reactions, and above the temperature of 140 °C, all alkane and alkene gases underwent the rapid concentration increase stage

Direct fitting measurement of gas content in coalbed and selection of reasonable sampling time

In this study, we selected 9 typical coal samples with different metamorphic grades as the study subjects, measured their initial 30-min gas desorption at 30 °C and different pressure using a self-developed gas adsorption/desorption device. Based on the characteristics of gas desorption from coal samples, we proposed a direct fitting method for measurement of gas content in coalbed, analyzed the effects of sampling time on the measurement results and determined the reasonable sampling time of coal samples with different metamorphic grades at different gas adsorption pressure at equilibrium. The results show that (1) the error of gas contents obtained using the direct fitting method relative to that obtained using indirect method is less than 10%, which meets the actual on-site requirements and verifies the feasibility of the direct fitting method; (2) when the relative error is controlled within ±10%, the reasonable sampling time of coal samples is linearly related to the gas adsorption pressure at equilibrium; (3) the reasonable sampling time of coal samples with the same metamorphic grade exhibits a shortening trend with increasing gas adsorption pressure at equilibrium; (4) for coal samples with similar gas adsorption pressure at equilibrium, the reasonable sampling time of coal samples displays a shortening trend with increasing metamorphic grade. Overall, the study provides a basis for improving the measurement accuracy of gas content in coalbed. Keywords: Gas content, Fitting, Desorption, Metamorphic grade, Sampling tim

Study on experiments and numerical simulation of coal combustion characteristics under different thermal environments

In order to study heat release rate and flue gas generation during residual coal in goaf combustion, a cone calorimeter was used to research on combustion characteristics of bituminous coal under different heat radiation flux conditions. A novel coal fire FOAM solver for coal combustion is developed, numerically simulated by varying the gas atmosphere, and compared with the above experimental results. The results showed that with the increase in heat radiation flux, the shorter the time to reach the peak heat release rate, the greater the maximum heat release rate. When the coal does not enter the ignition stage, the CO production rate is higher than that after ignition, and the CO2 production rate is lower than that after ignition. Compared with the experimental results of the cone calorimeter, the difference between the two results is very small, which verified the feasibility and accuracy of the coal combustion model. After the injection of the composite inert gas, the heat release rate and mass loss rate of coal combustion have varying degrees of lag. The numerical simulation results can provide a theoretical basis for injecting inert compounds into the goaves of coal mines to prevent the spontaneous combustion of coal

Synthesis and structure of novel 1,2,4-triazole derivatives containing the 2,4-dinitrophenylthio group

Some novel 1,2,4-triazole derivatives containing the 2,4-dinitrophenylthio group have been synthesised in high yields by means of the reactions of 3-substituted-4-amino -1H-1,2,4-triazole-5(4H)-thiones or (E)-3-aryl-4-(benzylideneamino)-1H-1,2,4-triazole-5(4H)-thiones with 1-chloro-2,4- dinitrobenzene. The (E)-3-aryl-4-(benzylideneamino)-1H-1,2,4-triazole-5(4H)-thiones were prepared by the reaction of 4-amino-3-aryl-2H-1,2,4-triazole-3(4H)-thiones and diverse aromatic aldehydes. The 2, 4-dinitrophenyl group linked to the S atom, not to the N atom, was confirmed by the crystal structures. The structures of all the compounds were determined by elemental analysis, IR, MS, H-1 NMR and C-13 NMR

Study on the Low-Temperature Oxidation Law in the Co-Mining Face of Coal and Oil Shale in a Goaf—A Case Study in the Liangjia Coal Mine, China

The low-temperature oxidation law of coal and rock mass is the basis to study spontaneous combustion in goafs. In this paper, the low-temperature oxidation laws of coal, oil shale, and mixtures of coal and oil shale were studied by using laboratory programmed heating experiments combined with a field beam tube monitoring system. The results from the programmed heating experiments showed that the heat released from oil shale was less than that from coal. Coal had a lower carbon monoxide (CO)-producing temperature than oil shale, and the mixture showed obvious inhibiting effects on CO production with an average CO concentration of about 38% of that for coal. Index gases were selected in different stages to determine the critical turning point temperature for each stage. The field beam tube monitoring system showed that the temperature field of the 1105 co-mining face of coal and oil shale in the goaf of the Liangjia Coal Mine presented a ladder-like distribution, and CO concentration was the highest for coal and lower for the mixture of coal and oil shale, indicating that the mixture of coal with oil shale had an inhibiting effect on CO production, consistent with the results from the programmed heating experiments