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To improve the adsorption and reusability of polypropylene (PP) fiber membranes, the organically modified saponite (Sap@P(St-co-MMA)) was prepared by solution polymerization. Furthermore, PP-based nanocomposite fiber membranes with strong oil adsorption, thermal stability, and reusability were prepared via melt-blown technology. The increased specific surface area of PP-based nanocomposite fiber membranes (PP-1.5%) provided more active sites for the oil adsorption. Simultaneous rheology and Fourier transform infrared measurements tests showed that Sap@P(St-co-MMA) enhanced the crystallinity of PP matrix, promoted the regular arrangement of molecules, and improved the intermolecular interaction force, which was beneficial for the oil adsorption. The adsorption of PP-1.5% (1.5 wt% addition of Sap@P(St-co-MMA)) fiber membrane for xylene and kerosene reached a maximum of 15.84 and 22.84 g [g.sup.-1], respectively. In the treatment of coal tar wastewater, the removal rate of oil can reach 62.9%, and the removal rate can still reach 51.17% after five cycles of experiments. In summary, PP-1.5% fiber membrane does not produce secondary pollution to the environment, and is a kind of oil removal material with good application prospect. Highlights * PP-based nanocomposites fiber membrane with strong oil adsorption was prepared. * Organically modified saponite had strong heterogenous nucleation for PP matrix. * Sap@P(St-co-MMA) increased the specific surface area of PP-based fiber membrane. KEYWORDS adsorption behavior, organically modified saponite, poly (propylene) nanocomposites fiber membranes, reusability, 1 | INTRODUCTION In recent years, with the rapid development of various enterprises such as coal chemical industry, resulting in the increasing of oily wastewater as well as the frequent [...]

The mechanism by which nitrate inhibits nitrogen fixation in soybean (Glycine max L.) is not fully understood. Accumulation of ureide in soybean plant tissues may regulate the nitrogen fixation capacity through a feedback pathway. In this study, unilaterally nodulated dual-root soybeans prepared by grafting were grown in sand culture. They were subjected to the removal of the nodulated side roots, and were given either nitrate supply or no supply to the non-nodulated side roots for 3 days (experiment I). Additionally, they received nitrate supply to the non-nodulated side roots for 1–14 days (experiment II). The results showed that nitrate supply increased the levels of asparagine and ureide in soybean shoots (Experiment I). In Experiment II, nodule dry weight, nodule number, nodule nitrogenase activity, and nodule urate oxidase activity decreased significantly after 3, 7, and 14 days of nitrate supply. Ureide content in the shoots and nodules increased after 1, 3, and 7 days of nitrate supply, but decreased after 14 days of nitrate supply. There was a significant positive correlation between urate oxidase activity and nitrogenase activity. Hence, we deduced that nitrate supply increased the asparagine content in soybean shoots, likely inhibiting ureide degradation, which induced the accumulation of ureide in soybean shoots and nodules, and, in turn, feedback inhibited the nodule nitrogen fixation. In addition, urate oxidase activity can be used to assess the nitrogen fixation capacity of nodules. [ABSTRACT FROM AUTHOR]

Straw incorporation increases the amount of nutrients in soil and greatly impacts soil nitrogen and microbial communities. In this study, 15N‐labeled corn straw was used as the material, the experiment consisted of five treament (AS: placing the straw 15 cm above the soil surface, SM: using the straw to mulch the soil surface, B15: burying the straw 15 cm below the ground surface, B30: burying the straw 30 cm below the ground surface, B45: burying the straw 45 cm below the ground surface). The changes in 15N abundance in straw were analyzed. An estimation method for nitrogen release and uptake by field‐incorporated straw was proposed, and the relationships between nitrogen release and uptake and related microbes were established. The results showed that the exchange of nitrogen between maize straw buried in soil at different depths and the environment was not significant. The corn straw exposed to the air absorbed more nitrogen from the environment in the second year of decomposition, and the larger the area exposed to the air was, the more nitrogen was absorbed from the environment. The relative abundances of Burkholderiales, Flavobacteriales, Pseudomonadales, and Sphingobacteriales were significantly positively correlated with the straw decomposition rate and nitrogen release rate. The relative abundance of Rhizobiales was significantly negatively correlated with the straw decomposition rate and nitrogen release rate. The relative abundances of Sphingobacteriales, Flavobacteriales, and Pseudomonadales were significantly negatively correlated with the straw nitrogen uptake rate. [ABSTRACT FROM AUTHOR]

In the work, bismuth tungstate (Bi2WO6, orthorhombic system) photocatalyst nanomaterial was synthesized by hydrothermal method. The photocatalytic ozonation oxidation synergistic degradation on organic pollutants in coal chemical phenol-ammonia wastewater by Bi2WO6 was studied. The effects of ozone (O3) concentration, catalyst dosage, pH and O3 flow rate on the degradation efficiency of wastewater were investigated, respectively. The study found that the degradation processes of these four single factors were fitted kinetically and aligned with the pseudo second order kinetics model, and the maximum chemical oxygen demand (COD) removal rate of the coal chemical phenol-ammonia wastewater was 56.34%, 79.03%, 78.63%, and 79.66%, respectively. The COD removal rate reached 80.37% under the optimum reaction conditions. Additionally, the degradation process was optimized, which conformed to the pseudo second order kinetics model. Density functional theory (DFT) calculations showed that the adsorption energies of O3 at the Bi, W, and O atomic sites were -0.477 eV, -2.604 eV, and -0.421 eV, respectively, on the exposed crystalline surface of (131), indicating that O3 had a stronger interaction force with W, which was easy to be activated by the surface-transferred electrons to form reactive oxygen species and mineralize the organic pollutants. The catalytic mechanism indicates that the photocatalytic ozonation oxidation is primarily accomplished by producing •OH, 1O2, and ∙ O 2 - , which results in the degradation on organic pollutants in coal chemical phenol-ammonia wastewater. The analysis of water quality and GC–MS indicated that most pollutants present in coal chemical phenol-ammonia wastewater had degraded upon treatment. Furthermore, the BOD/COD ratio of coal chemical phenol-ammonia wastewater was increased from 0.25 to 0.32. Moreover, the COD removal rate only decreased to 70.25% after five cycles of the experiment, which demonstrated that the Bi2WO6 catalysts had a high stability and reusability, implying that it has great potential for application in coal chemical phenol-ammonia wastewater treatment. [ABSTRACT FROM AUTHOR]

Increasing planting density is one of the most effective ways to increase soybean yield, but supra-optimum density leads to an increase in the risk of lodged soybean. In this study, two varieties were selected. Heinong84 (lodging-susceptible variety, HN84) had planting densities of 200,000 plants/hm2, 300,000 plants/hm2, and 400,000 plants/hm2. Henong60 (lodging-resistant, HN60) had planting densities of 300,000 plants/hm2, 400,000 plants/hm2, and 500,000 plants/hm2. When the foliar application of uniconazole (50 mg/L) occurred at the beginning of the flowering stage (R1), the plant morphology, fiber composition, and mechanical properties of soybean internodes were determined at the podding and seed filling stages, and the yield was measured at the harvest stage. The results showed that spraying uniconazole at the R1 stage changed the morphology structure of soybean plants (i.e., plant height and petiole length reduction; stem diameter and leafstalk angle increase), improved the internode quality (i.e., increased breaking force, lignin content, cellulose content, hemicellulose content, and stem dry weight per unit length), and increased the number of grains per plant at the harvest stage. Thus, it is concluded that the application of uniconazole improved the plant population structure by changing the morphology of soybean plants, which was conducive to good light transmission and ventilation, improved the internode quality and lodging resistance, and increased the yield. [ABSTRACT FROM AUTHOR]