土壤重金属污染植物修复技术研究

总结了现有土壤重金属污染的植物修复技术,包括：植物萃取技术、植物固化技术、根圈生物修复技术和植物挥发技术,并对土壤重金属污染的植物修复技术的发展趋势进行了展望。     

Dynamic Analysis of Diffusion and Adsorption of Water‐Miscible and Water‐Immiscible Organic Vapors in Soil

A dynamic analysis of the diffusion and adsorption of water‐miscible volatile organic compounds (methanol and acetone) and water‐immiscible volatile organic compounds (benzene and toluene) in a soil pellet has been performed experimentally by using the single pellet moment technique. The experiments were conducted in a one‐sided single pellet adsorption cell at a temperature of 30 °C and varying relative humidities (0, 20, and 40 %). The results obtained with dry and wet systems showed that volatile organic tracers were adsorbed reversibly onto the soil. The overall adsorption equilibrium constants of both water‐miscible and water immiscible volatile organic compounds decreased with relative humidity. The sorption of water‐immiscible VOCs (benzene) onto soil was found to be much less than that of water‐miscible VOCs (methanol). The effective diffusivity of water‐immiscible volatile organic vapor (benzene) in the soil did not show a considerable change with relative humidity. In contrast, there was an appreciable change in the effective diffusivity for water‐miscible VOCs (methanol) with moisture.     

Ozonation and Fenton Treatment for Remediation of Diesel Fuel Contaminated Soil

The chemical treatment (ozonation and the Fenton) was applied for remediation of diesel fuel contaminated sand and peat. The chemical treatment of diesel adsorbed in peat resulted in lower diesel removal and required higher addition of chemicals than the chemical treatment of diesel in sand matrix. The reduction of absorbance at 254 nm gave evidence of aromatics degradation during the chemical treatment. Short-chained linear alkanes (C₁₁–C₁₈) were more effectively removed than branched (pristane + phytane) alkanes and long-chained linear alkanes (C₁₉–C₂₆) in both sand and peat. A rough estimation and comparison of chemical oxidation treatment (chemicals and energy) costs indicated that the low additions and costs of chemicals make the Fenton and Fenton-like treatment more cost-effective than ozonation. The application of combined chemical + biological treatment may increase the effectiveness of soil remediation and economical feasibility.     

修复土壤,腐植酸能做些什么

我国土壤污染形势严峻,已成为农产品安全和农业可持续发展的一大障碍."十一五"期间已将防治土壤污染列入重要议事日程,"全国土壤污染状况调查和防治项目"业已启动,2006年11月<农产品质量安全法>也开始实施.腐植酸学术界及行业又面临新的机遇和挑战.介绍了我国土壤污染的现状及其治理技术,阐述了腐植酸类物质(HS)修复污染土壤的研究进展、存在问题及应用的可行性,并对今后的研究开发及应用方向提出若干建议.     

超声波净化土壤中石油污染物室内实验研究

选取土壤中的含油数量、土与水之比、土壤的类别、以及超声处理的时间和功率等5个因素做了正交实验,反映了之间的相互作用,并分析了其中的各因素,即在土壤中清除石油污染物的效率。而土壤的类型影响净化效果很明显,从粘土与砂土比较,前者的TPH的清除率比较高。通过研究表明,充分利用超声波技术去修复石油污染的土壤,拥有广泛的发展前景。     

Application of Ultrasound‐Assisted Supercritical Extraction to Soil Remediation

The coupling of ultrasound to supercritical extraction with carbon dioxide has been evaluated as a green remediation technique for soils contaminated with pesticides. The study used samples of soil spiked with atrazine, an organophosphate and contaminant of widespread use. The influence of the operating temperature and pressure on the extraction of atrazine was studied. The extraction of atrazine was enhanced with the use of ultrasound relative to the results obtained from conventional supercritical extraction. This study, operated in semi‐continuous mode, demonstrates the possibility of increasing the yield of supercritical extraction by coupling with ultrasound instead of adding co‐solvents, which is a greener alternative for removing contaminants such as pesticides from soil matrices.     

Water‐Based Bitumen Recovery from Diluent‐Conditioned Oil Sands

Important process development aspects leading to more efficient bitumen recovery from diluent‐conditioned oil sands by water‐based methods are discussed. Bitumen viscosity of 0.5–2 Pa·s is required at the processing temperature and can be reduced to this level by bitumen dilution with an organic solvent. Oil sand porosity, however, poses a restriction on the amount of diluent that can be accepted by the oil sand. Also oil sand‐diluent conditioning time is an important process parameter and can vary from a few minutes for oil sands with low‐viscosity bitumen to several hours if viscosity of the bitumen is high. Additionally, the bitumen separation efficiency during digestion and flotation can be enhanced by reducing the bitumen/water interfacial tension through addition, for example, of tripolyphosphate to the aqueous phase.     

Partially Acetylated Sugarcane Bagasse for Wicking Oil from Contaminated Wetlands

Sugarcane bagasse was partially acetylated to enhance its oil‐wicking ability in saturated environments while holding moisture for hydrocarbon biodegradation. The water sorption capacity of raw bagasse was reduced fourfold after treatment, which indicated considerably increased hydrophobicity but not a limited capability to hold moisture for hydrocarbon biodegradation. Characterization results by Fourier transform infrared (FT‐IR), scanning electron microscopy (SEM), X‐ray diffraction (XRD), and surface area analyzer suggested that treated bagasse exhibited enhanced hydrophobicity and surface area. Oil wicking test results indicate that treated bagasse is more effective in wicking oil from highly saturated environments than raw bagasse and suggest that application of this material in remediation of oil spills in highly saturated wetlands is promising.     

Water‐vapor‐permeable polyurethane resin

The reaction of methylene diphenylene diisocyanate with ethylene glycol, dimethyl dimethoxysilane, dimethyl diethyloxysilene, and other additives in the presence of N,N‐dimethylformamide and toluene to form the structure of water‐vapor‐permeable polyurethane (PU) resin was proven with Fourier transform infrared spectra. Experimental results clearly showed that the amount of oxygen that permeated the film made with the PU resin increased with an increase in the concentration of ethylene glycol, diethylene glycol, or triethylene glycol. This was due to an increased number of hydrophilic groups attached to the backbone of the PU resin molecules. These hydrophilic groups, because of the intermolecular interactions between PU resin molecules, made PU resin molecules form an expanded conformation with large porosities. Interestingly, the water vapor permeability of the PU resin appeared to increase with an increasing concentration of ethylene glycol, dimethyl dimethoxysilane, or dimethyl diethoxysilane but not to increase with an increasing concentration of diethylene glycol, triethylene glycol, or poly(ethylene glycol) with dimethyl dimethoxysilane. The former was due to intermolecular interactions resulting in an expanded conformation with large porosities, but the latter was due to intramolecular interactions resulting in a compact conformation or a micellelike structure with small porosities. Therefore, the water vapor permeability of the former increased, but the latter remained unchanged or decreased. Our experimental results suggest that the use of poly(ethylene glycol) 400, ethylene glycol, dimethyl dimethoxysilane, and other strong hydrophilic compound in the preparation of modified PU resins substantially raises the amount of water vapor diffusing into films made with these resins. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 2002–2010, 2002     

异位化学氧化修复石油烃污染土壤的小试研究

以上海某化工厂区石油烃污染场地为研究对象,采用室内模拟小试实验,以碱性激发剂氢氧化钠强化过硫酸盐为氧化剂,开展异位化学氧化修复小试研究,确定了过硫酸盐异位修复实施的关键参数。通过正交实验确定了最佳工艺条件为:激发剂NaOH投加量为0. 6%(ω)、Na_2S_2O_8投加量为2%(ω)、水土比为1∶1,反应时间为40 h。经验证,在此条件下实验结果 TPH去除率57. 6%,该结果可为实际的污染场地异位化学氧化修复工程的开展提供理论依据。     

油田污染土壤修复技术研究

随着人们对油气资源求日益提高,各大油田不断的加大原油的发力度,而在这个生产过程中不可避免的会对环境造成污染。文章综述了原油发对油田生态环境的影响,并针对油田发对其生态环境的污染,重点介绍了物理、化学和生物等油田生态环境污染的修复技术。     

化学强化重金属污染土壤植物修复研究进展

化学方法作为植物修复的辅助措施,能有效提高土壤重金属污染的修复效率。综述了化学方法强化重金属污染土壤植物修复的研究进展,重点讨论了螯合剂、表面活性剂和酸碱调节剂强化植物修复的作用机制及应用效果,并展望了今后的研究方向。     

铅锌冶炼企业重金属复合污染土壤的淋洗修复研究

针对铅锌冶炼矿区重金属复合污染土壤,采用土柱淋洗的方法对污染土壤进行化学淋洗,选用HCl、草酸和EDTA作为淋洗剂进行淋洗筛选实验,再对最佳淋洗剂进行单因素实验研究,并用动力学模型拟合重金属解析过程。结果表明:当浓度为0.1mol/L,淋洗时间为30h时,EDTA对重金属Cu、Pb、Zn的去除率分别达到39.02%、17.69%和38.88%,明显高于HCl和草酸,因此选择EDTA为最佳淋洗剂。单因素实验表明:最佳淋洗条件为:EDTA浓度0.05mol/L,淋洗时间36h,淋洗速率1.5ml/min,此时对Cu、Pb、Zn三种重金属的去除率分别达到69.50%、23.58%、99.18%,去除率最高;用四种模型对淋洗反应进行动力学模拟,其拟合度优劣排序为:二级动力学方程双常数模型Elovich模型一级动力学方程。     

Predicting the Viscosity of Non‐Newtonian Water‐in‐Oil Emulsions Based on the Lederer Model

The accurate prediction of the viscosity of emulsions is highly important for oil well exploitation. Commonly used models for predicting the viscosity of water‐in‐oil (W/O) emulsions composed by two or three factors cannot always fit well the viscosity of W/O emulsions, especially in the case of non‐Newtonian W/O emulsions. An innovative and comprehensive method for predicting the viscosity of such emulsions was developed based on the Lederer, Arrhenius, and Einstein models, using experimental data. Compared with the commonly applied W/O emulsion viscosity models, the proposed method considers more factors, including temperature, volume fraction of water, shear rate, and viscosity of the continuous (oil) and dispersed phase (water). Numerous published data points were collected from the literature to verify the accuracy and reliability of the method. The calculation results prove the high accuracy of the model.     

Acid Enhanced Electrokinetic Remediation of a Contaminated Soil using Constant Current Density: Strong vs. Weak Acid

The most typical enhancement for electrokinetic remediation (EKR) involves the neutralization of the alkaline front generated at the cathode by the addition of an acid to the catholyte. Although the use of strong and weak acids can be found in the literature, there is still a clear lack of reliable comparisons between them. This paper presents a comparison of the results obtained for a real lead contaminated soil treated by EKR enhanced with nitric or with acetic acid. The divergences that are usually observed in those experimental results obtained when using constant voltage drop are avoided here by the use of EKR with constant current intensity and the disposition in series of the soil lab columns. Important differences are observed in the behavior of the system when the acid was changed. The time needed to achieve the same metal recovery is more than 3 times longer for the nitric acid. A standard sequential extraction procedure was used to fractionate the lead concentration in the soil according to its mobility in a before- and after-treatment way. Regardless of these important differences observed in the remediation time, the fractionation results after the experiments were almost the same for the two acid enhanced EKRs.     

土壤重金属污染及修复技术研究进展

土壤重金属污染已经成为一个全球性环境问题。主要对目前国内外土壤重金属污染情况、污染的生态危害以及目前主要的土壤重金属污染修复技术包括物理修复、化学修复、植物修复和微生物修复技术进行了综述。并结合未来土壤重金属污染的趋势,对土壤重金属污染的防治提出了建议。     

重金属污染土壤修复研究进展

世界范围内的土壤中广泛存在重金属污染,正确认识土壤中重金属的存在形式有利于采取适当的方式进行土壤修复.现有技术中,根据修复原理可分为物理、化学、生物、电气和热修复五种,具体方法为覆盖、封装、填埋、土壤冲洗、电动萃取、稳定化/固化、玻璃化、植物修复及微生物修复.这些技术具有相应的优缺点和适用性,覆盖、封装和填埋适用于污染...     

Protein Synthesis in Sub‐Micrometer Water‐in‐Oil Droplets

Water‐in‐oil (w/o) emulsions are used as a cellular model because of their unique cell‐like architecture. Previous works showed the capability of eukaryotic‐cell‐sized w/o droplets (5–50 μm) to support protein synthesis efficiently; however data about smaller w/o compartments (<1 μm) are lacking. This work focuses on the biosynthesis of the enhanced green fluorescent protein (EGFP) inside sub‐micrometric lecithin‐based w/o droplets (0.8–1 μm) and on its dependence on the compartments’ dynamic properties in terms of solute exchange mechanisms. We demonstrated that protein synthesis is strongly affected by the nature of the lipid interface. These findings could be of value and interest for both basic and applied research.     

Under‐Oil Superhydrophilic Poly(vinyl alcohol)/Silica Hybrid Nanofibrous Aerogel for Gravity‐Driven Separation of Surfactant‐Stabilized Water‐in‐Oil Emulsions

For efficient and green separation of surfactant‐stabilized water‐in‐oil (W/O) emulsions, under‐oil superhydrophilic poly(vinyl alcohol) (PVA)/silica hybrid nanofibrous aerogel is fabricated by freeze‐drying the dispersion of shortened PVA/tetraethyl orthosilicate composite electrospun nanofibers in t‐butanol, followed by heat‐treatment. Its hierarchical porous structure, observed by scanning electron microscope, consists of major and minor pores with an average diameter of 15.9 and 1.0 µm, respectively. The silica‐based crosslinking structure inside the nanofibers and the chemical linkage between them, evidenced by infrared spectroscopy, endows the nanofibrous aerogel with desirable stability in water and compression recoverability. When it is used for gravity‐driven separation of Span80 stabilized water‐in‐n‐hexane emulsion, the flux is 2083 L m^?2 h^?1 and the purity of the separated n‐hexane reaches 99.997%, corresponding to the separation efficiency of 99.79%. The nanofibrous aerogel after use is readily recycled by rinsing and freeze‐drying, without using any organic solvent, as it possesses under‐oil superhydrophilicity and prominent oil antifouling property. Differing from the previously reported separation materials, PVA/silica hybrid nanofibrous aerogel simultaneously acts as gravity‐driven filtration material and adsorption material to both absorb their coalesced water droplets and allow the separated oil to penetrate in the separation process.