This study investigated the vermicomposting of spent drilling fluid (SDF) from the nature-gas industry mixed with cow dung in 0% (T1), 20% (T2), 30% (T3), 40% (T4), 50% (T5), and 60% (T6) ratio ...employing Eisenia fetida under a 6 weeks trial. Eisenia. fetida showed better growth and reproduction performances in the first three vermireactors (T1–T3), and the mortality was higher in the vermireactors that contained more spent drilling fluid (≥40%). Vermicomposting results in a decrease in total organic carbon, C/N ratio, and an increase in EC, total nitrogen, total phosphorous, total potassium compared to their initial values. The RadViz and VizRank showed that vermicomposting results in a greater impact on the C/N ratio (15.24–35.48%) and EC (7.29–26.45%) compared to other parameters. Activities of urease and alkaline phosphatase during vermicomposting initially increased and then declined suggesting vermicompost maturity. Also, seed germination, mitotic index and chromosomal abnormality assays using cowpea signified that the vermicomposts T2 is suitable for agricultural use due to the lower phytotoxicity and cytotoxicity. The results indicated that SDF could be converted into good quality manure by vermicomposting if mixed up to 20% with cow dung.
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•Mixing of spent drilling fluid with cow dung at 1:4 ratio can be converted by Eisenia fetida.•Vermicompost significant affected the C/N ratio and electrical conductivity.•Vermicompost with 20% spent drilling fluid is suitable for agriculture use due to the lower phytotoxicity and cytotoxicity.
In view of the eutrophication of the water environment caused by fertilizer leaching and the problem of nondegradability of the current slow-release fertilizers, potassium humate (KHA), sodium ...alginate (SA), and acrylic acid (AA) were used as raw materials to synthesize a KHA/SA/PAA hydrogel-based sustained-release material onto which urea was loaded. Infrared spectroscopy and scanning electron microscopy analyses indicated that KHA, SA, and, AA had undergone graft copolymerization. The polymer network exhibited a porous structure, and its degradation rate was 1.21%/day. The swelling and diffusion models of materials under different pH conditions are discussed. The material’s equilibrium swelling rate was as high as 621.46% at pH 7. The results indicated that the diffusion of urea from the material was non-Fickian in character and urea release was favored in an acidic environment, a behavior in accordance with the first-order kinetic equation and Higuchi equation. Potted vegetable experiments indicated the optimal dosage of soil and KHA/SA/PAA sustained-release fertilizer to be 500:1. After 14 days, the soluble protein content of green cabbage leaves and chlorophyll could be increased by 31.4% and 33.2%, respectively, whereas the malondialdehyde content could be reduced by 21.1%, indicating that soil treatment with the KHA/SA/PAA sustained-release fertilizer can effectively improve crop quality.
Biochar (BC) combined with humic acid (HA) and wood vinegar (WV) was designed and prepared as an inexpensive, effective, and environmentally friendly immobilization material (BHW) for metal-polluted ...soil. The influences of the wood vinegar and humic acid on the immobilization properties and adsorption mechanism of this new material were also investigated. The remediation performance was evaluated using a laboratory-made, nickel-contaminated soil with a Ni2+ concentration of 200 mg per kg surface soil (top 20 cm from agricultural land). The results indicated that the immobilization ratio sequence of nickel (II) in the soil was BC< BH< BHW. The maximum adsorption capacity increased in the same order: BC< BH< BHW. All three adsorption isotherms were better fitted by the Freundlich model, which were consistent with the surface heterogeneity of the remediation materials. The cause of this surface heterogeneous migration may be due to the increase in oxygen-containing groups in the BC introduced by the HA and WV. The WV can increase the number of the oxygen-containing groups in the BC combined with HA, which enhanced the adsorption and immobilization of Ni2+ ions. The results suggested that BHW is recommended for the remediation of metal-contaminated soils, because of its high efficacy, economic feasibility, environmental and food safety.
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•Biochar-humic acid-wood vinegar (BHW) effectively immobilizes nickel metal in soil.•Remediation material BHW is made by biochar supported humic acid and wood vinegar.•Wood vinegar from industrial by-product is reused for environmental remediation.•Wood vinegar improves oxygen-containing group in the remediation material BHW.•Soil remediation by the BHW is sustainable and low-cost remediation technique.
In this study, humic acid (HA) and polybutylene succinate (PBS) were compounded by melt blending to prepare a HA/PBS composite mulch. The compound was subjected to three conditions by placement in ...direct sunlight (on the soil), in the soil, and in the shade of plants. The crystallization performance, thermal performance, mechanical properties, degradation performance, and water vapor transmission rate of the mulch film at 21, 42, and 63 d, and the effect of the HA/PBS composite mulch film on the growth of lettuce, were studied. The crystallization experiment showed that in the three cases, the crystalline form of the composite mulch film was not affected by time, but the degradation by other factors caused the crystallinity of the film to decrease. The positional variables had little effect on the thermal performance. Analysis of the mechanical properties showed that the tensile strength and elongation at break decreased for the films subjected to all conditions. Analysis of the degradation performance and water vapor transmission rate showed that the composite mulch film degraded fastest when shaded by plants, followed by that in the soil, and was the slowest under exposure to sunlight. Evaluation of the effect of the compound mulch film on the growth of green vegetables showed that the film can promote the synthesis of chlorophyll, peroxidase, and vitamin C in the leaves of lettuce and inhibit the production of malondialdehyde.
•Prepared functional nutrient HA/PBS biodegradable agricultural mulch.•The HA/PBS mulch film has a good comprehensive performance and is easier for water molecules to penetrate.•The mulch film has a good promoting effect on the growth of green vegetables.
To achieve environmental protection, high removal rates, reusability, and degradability, a carboxymethyl-functionalized porous hydrogel P-(CM-β-CD/HPCS/KHA/AC) was synthesized with carboxymethyl ...cyclodextrin (CM-β-CD), hydroxypropyl chitosan (HPCS), potassium humate (KHA), and activated carbon (AC) using polyacrylic acid (PAA) as the carrier. The gel materials before and after adsorption were characterized via FTIR, TG, XRD, and XPS. Results showed high adsorption capacity for antibiotics such as tetracycline hydrochloride (TCH). P-(CM-β-CD/HPCS/KHA/AC) hydrogel exhibits optimal TCH adsorption at 298 K with 0.8 g/L of the adsorbent at pH 4, resulting in the highest adsorption capacity of up to 108.81 mg/g, a removal rate of 69%, and an adsorption equilibrium time of 150 min. The maximum swelling ratio is 100.39 times at pH 7. The theoretical values of the TCH adsorption capacity obtained using the quasi-second-order kinetic equation at 298 K, 308 K, and 318 K are 114.8106, 98.4552, and 90.4159 mg/g, respectively, corresponding to the experimental values. The adsorption behavior follows a quasi-second-order kinetic equation, which is in accordance with the Langmuir model. It is driven by electrostatic interactions, π–π conjugation reactions, hydrogen bond interactions, entropy increase, and heat absorption, resulting in a spontaneous process. The regeneration and degradability of the P-(CM-β-CD/HPCS/KHA/AC) hydrogel were tested. After five cycles of adsorption–desorption experiments, the removal rate was 50.57%. After degradation for 6 months, the weight loss rates of the P-(CM-β-CD/HPCS/KHA/AC) hydrogel in acid, water, and alkali were 45.29%, 24.90%, and 29.50%, respectively, indicating the environment-friendly nature and repeated recyclability of the hydrogel.
Heavy metal lead is a typical widespread potentially toxic element (PET) contamination due to their extensive and wide applications in industrial processes. The development of cost-effective methods ...for preventing potentially toxic element lead residues from soil into food is thus highly desirable. A new type of humic acid-based remediation material (HA/WV) incorporating humic acid salt (HA), biochar powder (BC), and wood vinegar (WV), which is a cheap and environmentally friendly industrial by-product from charcoal processing, was prepared and evaluated. The results showed that 0.10 g remediation material HA/WV with a mass ratio of 1:1 was added to 1 kg surface soil of 0–20 cm from agricultural land contaminated by 300 mg Pb
2+
, the reduction ratio of available Pb in soil can reach 61.4%. Especially, wood vinegar can enhance the reduction ratio of available Pb by at least 14.7% over without wood vinegar. Furthermore, according to the analysis of adsorption interaction and the electrostatic attraction between Pb(II) and oxygen-containing functional groups on HA/WV are the dominant mechanisms responsible for Pb(II) sorption. The wood vinegar liquid can improve the oxygen-containing group in HA/WV, which can enhance the complexation of remediation materials and Pb(II) ion.
We report multilayer nanocrystal quantum dot light-emitting diodes (QD-LEDs) fabricated by spin-coating a monolayer of colloidal CdSe/CdS nanocrystals on top of thermally polymerized ...solvent-resistant hole-transport layers (HTLs). We obtain high-quality QD layers of controlled thickness (down to submonolayer) simply by spin-coating QD solutions directly onto the HTL. The resulting QD-LEDs exhibit narrow (∼30 nm, fwhm) electroluminescence from the QDs with virtually no emission from the organic matrix at any voltage. Using multiple spin-on HTLs improves the external quantum efficiency of the QD-LEDs to ∼0.8% at a brightness of 100 cd/m2 (with a maximum brightness over 1000 cd/m2). We conclude that QD-LEDs could be made more efficient by further optimization of the organic semiconductors.
Soil contaminations by heavy metals near oilfields have been widely reported and are causing great concern. Thus, it is highly desirable to develop cost-effective materials and methods to avoid heavy ...metal residues contaminating soil and food. An effective, environmentally friendly, and inexpensive remediation material for heavy metal-polluted soil was designed and prepared using biochar (BC) combined with humic acid (HA) resulting from sodium humate (NaHA) simply reacting with wood vinegar (BHW). After adding BHW, the chemical fractions of copper and cadmium in the soil undergo larger changes. Meanwhile, the availability of heavy metals decreases. The maximum adsorption capacity of copper and cadmium in the soil using the BHW is larger than that only using biochar. The adsorption kinetics ensures that the adsorption process of Cd2+ and Cu2+ ions on BHW is chemical adsorption, which is best fitted using the pseudo-second-order rate equation. The thermodynamics guarantees that the metal ions adsorb on the heterogeneous surface of BHW in multilayer, which is credited to the enhancement of oxygen-containing groups in the biochar combined with the humic acid. The remediation material BHW holds promise for the immobilization of heavy metal in the soils and could be recommended based on its economic feasibility, high efficacy, and environmental safety.
矿产资源是人类经济社会发展的重要物质基础，然而在矿产资源的开采过程中，重金属等污染物在土壤环境介质中迁移，最终对矿区生态环境和人体健康造成严重威胁。矿区地质地貌复杂、土壤理化性质变异性大、污染物迁移转化过程复杂、现有土壤污染修复不彻底等成为矿区土壤污染修复主要限制因素。本文通过分析近年来矿区土壤污染修复研究成果，系统提出了构建地形地貌修复基本理念，综述了原位提取、钝化、纳米材料、联合修复以及新理念五类矿区土壤重金属污染修复技术的研究现状和最新研究进展，归纳总结了现有技术的适用范围和优缺点，提出了矿区土壤污染修复技术的未来发展方向，旨在为矿区重金属污染土壤修复的研究与实践提供理论参考。 Mineral resources are considered significant material sources for economic and social development. However, during mining processes, various toxic pollutants, such as heavy metals, are released into the soil environment, which pose serious threats to the ecological environment and human health in mining areas. In addition, intricate geology, geomorphology, and changes in soil physicochemical properties, as well as complex processes comprising the migration and transformation of pollutants, complicate the remediation of soil environments. Given the lack of existing technology, such as inadequate soil remediation, we analyzed the recent achievements in the remediation of contaminated soils in mining areas and introduced the basic concept of land restoration. Moreover, we introduced the theoretical and experimental research status of five types of typical treatment technologies for heavy metals, including extraction, passivation, nanotechnology, combination, and new concept techniques in detail subsequently, we also described the advantages and limitations of the application of existing remediation techniques. This study aims to provide directions for future research on soil pollution control, treatment technologies, and remediation practices in mining areas.
Mesh division plays an important role in applications of the finite element method (FEM). The proposed research shows that under the same order, the equilateral triangular meshes have the most ...uniform dispersion distribution. The isosceles triangles with equal base and height have more uniform dispersion error than the square meshes, while the maximum phase error is similar. Taking the rectangular waveguide as an example, the relative errors in the cut-off frequency are analyzed based on different meshes. The numerical results show that under the same interpolation order and node numbers, the relative error of isosceles triangles with equal base and height for TE10 mode is the smallest. The results are useful in choosing appropriate element order, node density and mesh shape when applying FEM.
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