Electrochemical conversion is emerging as a powerful and promising method to produce a wide range of high-value chemicals on account of mild operation conditions, controllable selectivity, and ...scalability. 5-Hydroxymethylfurfural (HMF), with simple molecular structures including furan rings, -C&z.dbd;O, and -OH groups, is considered one of the most versatile platform molecules. The electrooxidation of bio-based HMF to furandicarboxylic acid (FDCA), a crucial bio-based precursor of polyethylene furanoate (PEF), which would probably replace petroleum-based polyethylene terephthalate (PET), has recently attracted increasing attention. Here, we review the HMF electrochemical oxidation, from reaction pathway/mechanism to catalysts and coupling reactions. First, a pH-dependent reaction pathway is proposed, and the reaction mechanism (direct oxidation and indirect oxidation) is summarized systematically, which is also suitable for electrochemical oxidation of other small organic molecules containing aldehyde/alcohol groups (
e.g.
, methanol, ethanol, glycerol, and glucose) to some extent. Then, the progress, advantages and disadvantages of HMF electrooxidation catalysts of noble metals, non-noble metals, and non-metals are reviewed, particularly on non-noble metal catalysts. Furthermore, for more efficient energy utilization, HMF electrooxidation coupled with H
2
evolution, CO
2
reduction, N
2
reduction, and organic reduction are discussed. Finally, a few unique insights into reaction mechanism, an assessment about catalyst performance and an outlook for further development of this topic are provided. This review can offer a guideline for the in-depth understanding of electrochemical oxidation of small organic molecules as well as the design of advanced anodic electrocatalysts towards the utilization and production of renewable resources.
HMF electrooxidation is emerging as a powerful and promising method to produce a wide range of high-value chemicals on account of mild operation conditions, controllable selectivity, and scalability.
Because of its strong pollutant degradation ability, nanoscale zerovalent iron (NZVI) has been introduced to soils and groundwater for remediation purposes, but its impacts on plants are still not ...very clear. In this work, the effects of low concentration (10-320 μmol/L) NZVI particles on seed germination and growth of peanut plants were evaluated. The exposure of peanut seeds to NZVI at all the tested concentrations altered the seed germination activity, especially the development of seedlings. In comparison with the deionized water treated controls (CK), all of the NZVI treatments had significantly larger average lengths. Further investigations with transmission electron microscopy (TEM) and thermogravimetric analysis (TGA) suggested that NZVI particles may penetrate the peanut seed coats to increase the water uptake to stimulate seed germination. The growth experiments showed that although NZVI at a relatively high concentration (320 μmol/L) showed phytotoxicity to the peanut plants, the lower concentrations of NZVI particles stimulated the growth and root development of the plants. At certain concentrations (e.g., 40 and 80 μmol/L), the NZVI treated samples were even better than the ethylenediaminetetraacetate-iron (EDTA-Fe) solution, a commonly used iron nutrient solution, in stimulating the plant growth. This positive effect was probably due to the uptake of NZVI by the plants, as indicated in the TEM analyses. Because low concentrations of NZVI particles stimulated both the seedling development and growth of peanut, they might be used to benefit the growth of peanuts in large-scale agricultural settings.
•Fertilizer mixture of controlled-release urea (CRU) and normal urea increased crop yield, NUE, and net farm profit, compared with normal urea.•Release rates of CRU in water and soil were ...investigated.•Releases rates of N from fertilizer mixture corresponded well to the N requirements of wheat and maize plants.•Fertilizer mixture reduced the leaching of inorganic nitrogen from the crop root zones, compared with normal urea.
Controlled-release urea (CRU) has been shown to improve nitrogen use efficiencies (NUEs) and yields in wheat and maize crops, although high cost has limited its use. From October 2013 to September 2015, the effects of a fertilizer mixture (polymer coating of sulfur-coated urea, polymer coated urea, and normal urea with N ratios of 3: 3: 4, respectively, during the wheat growing season, and 3.5: 3.5: 3, respectively, during the maize season) on crop yields and nutrients uptake were investigated in a field using a wheat (Triticum aestivum L.) and maize (Zea mays L.) rotation system. Crop residues were returned into the field at the end of the growing season. Before planting each crop, the fertilizer mixture was applied once as basal dressing at two application rates of 225kgNha−1 (CRU1) and 150kgNha−1 (CRU2). Meanwhile, the equivalent rates of normal urea (BBF1 and BBF2) used as twice-split fertilization, 60% at pre-plant and 40% at jointing stage of wheat or V12 (twelve leaf collar) stage of maize as the control. The results suggested that blended applications of CRU and normal urea fulfilled the wheat and maize plants demand for nitrogen during the entire growth periods with crop residues were returned into the field. The yields in the CRU1 treatment were increased by 7.9–10.3% for wheat and 9.1–21.0% for maize, compared with normal urea treatment at the same nitrogen application rates. The NUEs in the mixture treatments were increased by 33.7–56.4% for wheat and 16.7–48.5% for maize, respectively, and the average annual net profit was also increased by 14.5–19.9%, compared with normal urea treatments at the same nitrogen application rates. Although the treatment of CRU2 supplied one-third less N, its yield was similar with that of urea at 225kgNha−1. However, the BBF2 treatment supplied one-third less N, the yields were significantly decreased by 6.1–11.1% for wheat and 7.2–9.4% for maize than that the urea at 225kgNha−1. In addition, the mixture treatments significantly increased the quality and quantity of tillering of wheat. Furthermore, the NO3−-N and NH4+-N concentration in soil were enhanced especially during the later crops stages, and leaching of soil nitrogen was reduced by using the fertilizer mixture. These results demonstrate that combining CRU and normal urea improved crop yields and NUEs while decreasing costs of fertilizer and the labors required for fertilizer application.
In this paper, we synthesized a biobased polyurethane using liquefied corn stover, isocyanate, and diethylenetriamine. The synthesized polyurethane was used as a coating material to control nitrogen ...(N) release from polymer-coated urea. A novel superabsorbent composite was also formulated from chicken feather protein (CFP), acrylic acid, and N,N′-methylenebisacrylamide and used as an outer coating material for water retention. We studied the N release characteristics and water-retention capability of the double-layer polymer-coated urea (DPCU) applied in both water and soils. The ear yields, dry matter accumulation, total N use efficiency and N leaching from a sweet corn soil-plant system under two different irrigation regimes were also investigated. Comparison of DPCU treatments with conventional urea fertilizer revealed that DPCU treatments reduced the N release rate and improved water retention capability. Evaluation of soil and plant characteristics within the soil-plant system revealed that DPCU application effectively reduced N leaching loss, improved total N use efficiency, and increased soil water retention capability.
Water-soluble chelated calcium has been widely used in agriculture as a fertilizer to improve the absorption and utilization of calcium by plants. This paper prepared a new organic mineral ...fertilizer, based on fulvic acid-like substance chelated calcium (PFA-Ca2+ complex), using optimal parameters (i.e., pH, time, temperature, and Ca2+ concentration) to achieve a high chelation efficiency. The absorption, utilization, and distribution of the PFA-Ca2+ complex in rice roots were analyzed using laser scanning confocal microscopy (LSCM). Our results demonstrated that the optimal PFA-Ca2+ complex chelating efficiency (87%) was achieved at an initial Ca2+ concentration of 0.1 mol L−1, an equilibration time of 120 min, a pH of 5.0, and a temperature of 40 °C. The chelating reaction of a fulvic acid-like substance with Ca2+ primarily occurred on phenol hydroxyl, alcohol hydroxyl, and carboxyl groups. The PFA-Ca2+ complex was primarily enriched in the roots' pericycle, cortical, and epidermis cells, in both chelating and non-chelating forms. To our knowledge, this is the first report investigating how the PFA-Ca2+complex affects transformation in plants, which has significant implications for research on plant nutrition and nutrient distribution.
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•An eco-friendly and bio-renewable functional fertilizer was prepared.•PFA-Ca2+ enhances rice root development and nutrient absorption.•The speciation and distribution of PFA-Ca2+ can be visually visualized in the root.
•N release characteristic of PCU in field was closely matched the N requirements of cotton.•Interaction effects of PCU with S fertilizers were found in cotton yield and N use efficiency.•PCU and S ...addition delayed the senescence of cotton leaves.•The application of PCU combined with 60kgha−1 sulfur fertilizer was recommended on cotton cultivation.
Nitrogen (N) and sulfur (S) fertilization play important roles for improving cotton yield, but no studies have been implemented to explain their interaction on yield, nitrogen use efficiency and physiological characteristics of cotton. In order to investigate the interaction effects of polymer coated urea (PCU) and S fertilization on the contents of inorganic N and available S, enzymes activities of leaves and yield of cotton, the field experiment with different types of N fertilizers and S rates was carried out in 2014 and 2015. The experiment consisted of two N fertilizer types including PCU and common urea fertilizer (Urea) in combination with three S rates (0, 60 and 120kgha−1) in the split-plot design, where the types of N fertilizer were the main plot and S rates were the subplots. The results indicated that the N release characteristic of PCU in field condition was closely matched to the N requirements of cotton, the contents of soil nitrate nitrogen (NO3−-N) and ammonium nitrogen (NH4+-N) were significantly increased from the first bloom stage to the initial boll-opening stage by using PCU compared with urea. And the content of available S was significantly increased in full boll setting stage. Meanwhile, the number of bolls and lint yields of PCU were 7.03–8.91% and 5.54–11.17% higher than urea treatments. Lint yields were also increased 3.77–9.26% by S fertilization, evidencing a clear interaction between N and S, but no significant difference was observed between S60 and S120 treatments. In addition, the N apparent recovery use efficiency (RUE) and agronomic use efficiency (AUE) were increased, fiber length and strength were improved, the nitrate reductase and peroxidase activities and photosynthetic rates (Pn) were enhanced by PCU and S fertilization. However, the lint percentage, micronaire and fiber elongation were neither affected by the type of N fertilizers and S rates, nor by their interaction. Consequently, the application of PCU combined with 60kgha−1 sulfur fertilizer on cotton could not only increase the yield and nitrogen use efficiency but also improve the fiber quality and physiological properties of leaves.
Xiong'an New Area is defined as the future city of China, and the regulation of water resources is an important part of the scientific development of the city. Baiyang Lake, the main supplying water ...for the city, is selected as the study area, and the water quality extraction of four typical river sections is taken as the research objective. The GaiaSky-mini2-VN hyperspectral imaging system was executed on the UAV to obtain the river hyperspectral data for four winter periods. Synchronously, water samples of COD, PI, AN, TP, and TN were collected on the ground, and the in situ data under the same coordinate were obtained. A total of 2 algorithms of band difference and band ratio are established, and the relatively optimal model is obtained based on 18 spectral transformations. The conclusion of the strength of water quality parameters' content along the four regions is obtained. This study revealed four types of river self-purification, namely, uniform type, enhanced type, jitter type, and weakened type, which provided the scientific basis for water source traceability evaluation, water pollution source area analysis, and water environment comprehensive treatment.
The effects of a controlled release urea (CRU) on concentration of N in root zones, activities of N metabolism enzymes in leaves, and N use efficiency of rice (Oryza sativa L.) grown on a silt loam ...soil in lysimeters were investigated. The entire amount (100–300 kg N ha−1) of the CRU was incorporated into a plug for growing the rice seedlings while the regular urea was split into three applications (the standard practice). Results indicated that the N release of CRU closely matched the N requirements of the rice, and the commingling of the CRU with the rice seeds increased N concentration within the root zone and enhanced the activities of glutamine synthetase (GS), glutamine 2-oxoglutarate amidotransferase (GOGAT) and nitrate reductase (NR) in leaves. At the same N rate, the apparent N use efficiency of the CRU applied at 300 kg N ha−1 was 27.6 and 22.9% higher than that of conventional urea treatment in 2007 and 2008, respectively. Although the CRU at 200 kg N ha−1 supplied one-third less N than the urea at 300 kg N ha−1, the CRU produced 3 to 5.9% more grain than the urea. Placing the CRU with rice seeds without additional fertilizer application during the entire growing season significantly increased N availability in soils and improved rice growth and led to use of less N fertilizers for greater rice grain yield.
Purpose
Crops grow poorly in saline-sodic soils, and the productivity of these soils can be dramatically improved with proper amendments. Current research mainly focuses on either organic or ...inorganic soil amendments, whereas few studies address options of combining organic and inorganic amendments. The objective of this study was to develop new organic and inorganic soil amendments which can lower the soil pH, replace sodium, and improve soil structure.
Materials and methods
Polyhalite (PL), microporous potassium-silicon-calcium mineral fertilizer (MF), furfural residue (FR), and fulvic acid (FA) were mixed with four different ratios to produce organic and inorganic soil amendments: PLFR, PLFA, MFFR, and MFFA. And their optimum mixing ratios were determined by comparing the potassium, calcium concentrations, and pH of filtrate after dissolution. Then, a leaching experiment was conducted by packing mixtures (mass ratio of soil to amendment = 219:1, equivalent to 13 t/hm
2
) of the saline-sodic soil with each one of these amendments plus two contrasts, gypsum (GP), and no amendment (CK). And the remediation effect was compared by pH, EC, ESP, texture, organic recombination degree of clay, saturated hydraulic conductivity, water-stable aggregates fraction, and enzyme (urease, alkaline phosphatase, and catalase) activities of soil.
Results and discussion
After four times leaching experiment, soil treated with PLFR had lower pH and 25.86% lower exchangeable sodium than untreated soils. The water-stable small macroaggregate fractions and saturated hydraulic conductivity of the MFFR-treated soils were significantly increased by 133% and 31%, respectively. Also, the total soil and heavy fraction organic carbons of the soils treated with MFFR in addition to its alkaline phosphatase activity were all significantly higher than the other treatments.
Conclusions
The results revealed that MFFR has more potential as a soil amendment to improve soil structure and quality and thus help in the development and use of saline-sodic lands for agriculture.
Purpose
Bio-organic–chemical fertilizer (BCF) has great potential to enhance agricultural production, protect environment, and improve sustainability. However, current BCFs are used only in a limited ...scope mainly due to the low activity of beneficial bacteria. It is significant to develop new BCFs with high beneficial bacteria activity for sustainable agricultural production.
Materials and methods
In this study, a novel slow-release bio-organic–chemical fertilizer (SBCF) was prepared from activated lignite, bacillus AMCC100153 (B153) (beneficial bacteria for tomato), and slow-release fertilizer (CSF) with suitable pH and low dissolubility salt content (to protect the bacterial activity). The pH and EC of different types of SBCFs with different compositions were determined and compared with those of BCFs derived from common chemical fertilizers (BCCF). The B153 activities were measured and compared with the optimum formula of SBCF. The bacillus colonization rules of SBCF and BCCF in tomato pot soil were explored by the Real-time qPCR.
Results and discussion
SBCF had higher bacillus activity than the corresponding BCCF. Pot experiments also showed that the bacillus formed colonization rapidly on tomato roots and secreted substances to promote root growth. The HPLC analysis found that the promoting substances were auxin and zeatin. Compared with no fertilizer control (CK) and the BCCF treatments, the SBCF treatment increased tomato yields by 73.08% and 29.04%, respectively.
Conclusions
Findings of this work suggest that SBCF with high biological activity and growth promoting effect has great potential in agriculture production system in the future.
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