Ruxiang Qin

It has been demonstrated that iron-reducing bacteria (IRB) Acidiphilium cryptum JF-5 (Alphaproteobacteria) could release arsenic from secondary iron oxyhydroxides in mine areas. This study used injecting IRB technology to carry out arsenic sequestration experiments aimed at alleviating arsenic pollution. Temperature and acetate were found to enhance arsenic release from amorphous arsenic-containing hydroxides. A suitable temperature (35 °C) increased the release of arsenic(III) and arsenic(V) by more than 1.9–2.5 and 1.1–1.3 times, respectively. The addition of acetate increased arsenic(III) and arsenic(V) release by more than 2.8–6.1 and 1.1–1.3 times, respectively, compared to the control group. After injecting IRB into amorphous arsenic-containing hydroxide sediment, arsenic associated with particles/colloid was reductively released with aqueous arsenic(III) and arsenic(V), which account for 4%–334% of aqueous arsenic(III) and 6%–332% of aqueous arsenic(V), respectively. Results from the suspension solid also showed that the average values for the lower and upper sites are 131 mg/L and 118 mg/L, respectively. These suspension solids contain rich iron. The effectiveness of this IRB-assisted arsenic release technology became better under suitable temperature (35 °C) than at low temperature (8 °C) due to biological activity. These results suggest that microbially assisted reduction using iron-reducing bacteria may effectively release arsenic by sequestrating arsenic as aqueous and particle/colloidal phases.

Coal has been the fundamental energy source supporting China’s energy supply and consumption. This paper examines convergence clubs for per capita coal consumption among 30 provinces of China between 1997 and 2019 by means of a nonlinear time-varying factor model. Meanwhile, the ordered probit model is further used to identify the causes affecting convergence. The results of analyses of data strongly support the existence of convergence clubs, indicating that there are four convergence clubs and one divergence group at the interprovincial level. Among the factors that potentially influence provincial coal consumption, the GDP-per capital, industrial structure, intensity of environment regulations and carbon emissions are positively related to per capita coal consumption, while investment in fixed assets, degree of openness to the outside world and technological progress are negatively related to per capita coal consumption. Increases in GDP-per capital, industrial structure, intensity of environment regulations and carbon emissions enhance the odds of belonging to a high coal consumption intensity club. Increases in investment in fixed assets, degree of openness to the outside world and technological progress reduce the odds of belonging to a high coal consumptions intensity club. These findings help policy makers to set coal production and consumption targets for different regions and reduce the differences in coal consumption across regions.

A method for measuring thermal diffusivity of orthotropic materials by using multidimensional heat transfer model combined with parameter estimation is proposed. The unsteady mathematical model of three-dimensional temperature field is established by heat conductivity product method, the thermal diffusivity is calculated by random conjugate gradient method, and the thermophysical property testing system is developed. The constant-temperature boundary is constructed by using a constant-temperature water bath box combined with graphene stickers wrapped on the surface of the sample, the insulation material covers the upper surface of the sample to construct an insulating boundary, and thermocouples are arranged on the upper surface to monitor the temperature rise change. First, isotropic materials, such as acrylic plate and marble, were tested. Compared with a reference value, the maximum relative deviation of thermal conductivity was 3.72%, which verified the feasibility and accuracy of the test method. Furthermore, the orthotropic-material unidirectional carbon fiberboard was tested. Compared with the results measured by improved parallel hot-wire method, the relative deviations of thermal diffusivity, thermal conductivity, and specific heat capacity were 3.66, 1.59, and 2.15%, respectively, which indicate that this test method could meet the thermophysical testing requirements of orthotropic materials.

In order to solve the problem of the high cost of coal-based solid waste bulk stacking and paste filling in the large-scale coal electrification base in East NingXia, in this study, fly ash is skillfully used to replace the broken coal gangue as the mixed filling material. As using a jaw crusher for crushing large coal gangue is expensive, and its energy consumption is relatively high, paste filler using fly ash as aggregate is studied through micro and macro test analyses. Using response surface methodology design software, 29 groups of mix proportion schemes are designed to obtain the best mix proportion. In addition, the radar results of slump, slump flow, and comprehensive strength are obtained by the normalization method. According to the radar chart results of the three normalized indexes, the optimal ratio parameters are as follows: the fly ash in solid phase is 79%, the mass of fly ash to the mass of cement (FA/C) is 6:1, the solid mass concentration is 78%, the fly ash to gasification slag is 1:1, and the results show that σ_3d = 2.20 MPa, slump = 205 mm, and flow = 199 mm. Taking the solid mass concentration, FA/C, the fly ash content in solid phase, and the coal gangue-to-gasification slag ratio as independent variables, the influence of single-factor and multi-factor interactions of the independent variables are analyzed based on the response surface model. It is found that the solid mass concentration and FA/C have a very significant effect on the early strength. Replacing coal gangue base with fly ash base can effectively reduce the crushing cost and energy consumption and provide low-cost and highly reliable technical reserves for large-scale filling.

Reducing the fire hazard of polypropylene (PP) is an important research direction in the fields of fire safety materials. In this article, a novel Ni‐containing char‐forming agent (TTPN) was successfully synthesized, using tris(2‐hydroxyethyl) isocyanurate (THEIC), terephthalic acid, and nickel dihydrogen phosphate. Then, TTPN was combined with the silica‐gel microencapsulated ammonium polyphosphate (OS‐MCAPP) to prepare intumescent flame retardant PP composites. From the results of the limiting oxygen index (LOI) test and cone calorimeter, the composite containing 30% IFR (OS‐MCAPP: TTPN = 3:2) shows the highest LOI value of 33.5%, and its peak heat release rate is 275.5 kWm⁻², decreased by 79.0% and 37.4% than those of pure PP and the composite containing the char‐forming agent without Ni. Meanwhile, the composite containing TTPN present the best smoke and CO₂/CO suppression. The results indicate that TTPN has an excellent ability to dramatically reduce the fire hazard of PP.