In this study, corn cob was used as raw material and modified methods employing KOH and KMnO4 were used to prepare activated carbon with high adsorption capacity for mercury ions. Experiments on the effects of different influencing factors on the adsorption of mercury ions were undertaken. The results showed that when modified with KOH, the optimal adsorption time was 120 min, the optimum pH was 4; when modified with KMnO4, the optimal adsorption time was 60 min, the optimal pH was 3, and the optimal amount of adsorbent and the initial concentration were both 0.40 g/L and 100 mg/L under both modified conditions. The adsorption process conforms to the pseudo-second-order kinetic model and Langmuir model. Scanning electron microscopy and energy-dispersive X-ray spectroscopy (SEM-EDS), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and Zeta potential characterization results showed that the adsorption process is mainly physical adsorption, surface complexation and ion exchange.
As a by-product of lignocellulosic depolymerization for furfural production, furfural residue (FR) is composed of residual cellulose, lignin, humic acid, and other small amounts of materials, which have high reuse value. However, due to the limitation of furfural production scale and production technology, the treatment of FR has many problems such as high yield, concentrated stacking, strong acidity, and difficult degradation. This leads to the limited treatment methods and high treatment cost of furfural residue. At present, most of the furfural enterprises can only be piled up at will, buried in soil, or directly burned. The air, soil, and rivers are polluted and the ecological balance is destroyed. Therefore, how to deal with furfural residue reasonably needs to be solved. In this review, value-added products for furfural residue conversion are described in detail in the fields of soil culture, catalytic hydrolysis, thermal decomposition, and porous adsorption. The future studies reporting the FR to convert value-added products could find guidance from this review to achieve specific goals.
With the improvement of living standards, people pay more and more attention to the quality and safety of rice. Microbial agents are favored by the public because they can activate the nutrient supply in the soil, and reduce the residue and application amount of chemical fertilizers and pesticides. Based on the conventional fertilization in the field, Bacillus mucilaginosus and Aspergillus niger were applied, Bacillus mucilaginosus was inoculated at four levels in the paddy soil in the cold region of Heilongjiang Province of China. The effects of different proportions of Bacillus mucilaginosus and Aspergillus niger on the number of soil microorganisms, enzyme activity, microbial biomass, soil biochemical intensity, soil nutrient content, plant nutrient content and yield were studied, and the effects on the plant nutrient content of rice and the nutrient dynamics were discussed. The results showed that a 2.62%-21.20% higher yield of rice obtained from co-application treatments compared with that of the control-blank treatment. Furthermore, the highest yield obtained (10736±65 kg/hm 2) suggested that the optimized values for the two bacteria applied were 120×10 11 CFU/hm 2 for Bacillus mucilaginosus and 15×10 11 CFU/hm 2 for Aspergillus niger. Bacillus mucilaginosus can decompose minerals in soil, dissolve potassium and silicon, decompose apatite and release phosphorus into soil. Aspergillus niger can transform the phosphate which cannot be absorbed by plants into soluble phosphate which can be directly absorbed by plants by producing non-volatile acids. In particular, Bacillus mucilaginosus and Aspergillus niger have synergistic effect, and their combined application effect is greater than that of two bacteria alone. Co-application promoted the release of soil soluble silicon, and then increased the silicon content of plants. At the same time, soil microorganism, microbial biomass, enzyme activity and biochemical activity all increased significantly. This study provides an effective way to reduce the amount of chemical fertilizer applied in rice production in cold regions of China.
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