毒死蜱农药环境行为研究

研究了毒死蜱农药在环境中的水解、土壤吸附和土壤消解行为。实验结果表明,毒死蜱在水体中降解较慢,半衰期为 ２５．６ ｄ;土壤具有较强的吸持毒死蜱农药的能力;该农药在土壤中的消解也较慢。     

腐殖酸对铜的吸附与解吸特征

采用铜离子选择电极研究了铜在腐殖酸两组分(富里酸FA、胡敏酸HA)中的吸附-解吸特征,以及介质pH对这种吸附-解吸的影响。结果表明,腐殖酸对铜的吸附量为FA>HA,吸附强度为HA>FA,解吸量FA-Cu>HA-Cu。腐殖酸两组分对铜的吸附,当介质pH为4.00～7.00时,很好地符合Langmuir等温吸附方程;当pH<4.0时,符合Freundlich方程。FA、HA与铜作用的条件稳定常数与介质pH有关,pH提高则条件稳定常数增大;但在低pH段和高pH段,其增长规律不一致,当4.00相似文献   

改性腐殖酸对铀的吸附的试验研究

通过静态吸附实验,探讨了改性HA对U(Ⅵ)吸附影响。考查pH值、时间、U(Ⅵ)的初始浓度和温度等对吸附的影响。结果表明:pH值对改性腐殖酸的吸附效果影响较大,改性腐殖酸吸附U(Ⅵ)的最佳pH值为6,最大去除率为99.37%,吸附在60 min内基本达到平衡。UO22+在改性腐殖酸上的吸附是放热过程,符合Freundlich等温吸附方程,相关系数达0.99以上,表明IHA对铀的吸附是以表面为主要吸附位,并不是均匀的单层吸附。图8,参9.     

腐殖酸对铊污染土壤中铊形态和分布的影响

选用云浮含铊硫铁矿周围冲积土壤为供试样品,在土样中投加不同比例腐殖酸,采用连续浸提法对比研究了外源腐殖酸对受铊污染土中的铊不同形态及活性的影响.结果表明:随腐殖酸投入比的加大,酸可交换态含量明显下降,Fe/Mn氧化物结合态反之,有机质结合态与Fe/Mn氧化物结合态雷同,残余态几乎无变化;腐殖酸对酸可交换态铊分配比率最高为13.6%～30.5%,分别是有机态铊和Fe/Mn氧化态铊的2.8～15.1倍和2.8～3.7倍.结果说明腐殖酸有降低冲积土壤上有害活动态铊的功能,其作用机制在于腐殖酸具备的络合(螯合)能力和胶体特性.研究确认,腐殖酸可作为土壤重金属污染修复的优质材料.     

分子结构在腐殖酸对菲吸附行为中的影响

用连续碱提取具有不同结构组成特征的腐殖酸级分,考察了分子结构在腐殖酸对菲吸附行为中的影响,结果表明：随着腐殖酸中元素碳、表观分子量以及脂肪碳含量的增加,腐殖酸对菲的吸附能力和吸附的非线性特征都呈增强趋势;相反,随着腐殖酸中元素氧和芳香碳含量的增加,腐殖酸对菲的吸附能力和吸附的非线性都逐渐减弱,这主要与结构中极性官能团所连位置有关．     

黄铁矿对水体中腐殖酸的吸附特性

选择富里酸(fulvic acid,FA)和胡敏酸(humilic acid,HA)作为吸附对象,通过铁矿物吸附筛选实验,以黄铁矿(pyrite)为吸附剂研究其对水体中两种典型腐殖酸(humic acid)的吸附特性.利用X射线衍射(XRD)、扫描电子显微镜(SEM)、X-射线光电子能谱(XPS)、红外光谱(IR)、纳米粒度及电位(Zeta)分析仪和比表面仪(BET)对黄铁矿进行组成及结构表征.考察了腐殖酸溶液p H、离子强度和温度等条件对黄铁矿吸附的影响.结果表明,黄铁矿是层状结构,吸附腐殖酸后,在黄铁矿表面形成了大小均匀的分子簇,且黄铁矿晶粒尺寸减小了约10 nm;黄铁矿对FA、HA的最大吸附量分别为11.8 mg·g-1和13.1 mg·g-1.随着p H增加,黄铁矿对腐殖酸的吸附量均表现为先增大后减小;离子强度(NaCl)对吸附的影响较小;随着温度升高,其吸附量不断增大.两种腐殖酸吸附数据与Langmuir吸附模型拟合良好且其吸附动力学规律均符合二级动力学模型,热力学研究表明,黄铁矿吸附两种腐殖酸均属于自发进行的吸热反应.     

溶液化学对纳米二氧化钛吸附腐殖酸的影响

研究了环境相关pH(5.0-11.0)、盐度(NaCl和CaCl2 0-500mmol·L-1)条件下,纳米二氧化钛(nano-TiO2)对不同浓度腐殖酸(HA,以溶解性有机碳DOC计0-100mg·L-1)的吸附.结果表明,nano-TiO2对HA的吸附迅速达到平衡,符合Freundlich吸附等温线模型.对于高浓度...     

腐殖酸负载对萘和1-萘酚在生物炭上吸附动力学的影响

进入环境的生物炭对有机污染物的吸附过程受到普遍共存的溶解性有机质的影响.本研究将两种腐殖酸组分负载在以玉米秸秆为原料、不同炭化温度下(200、400、600℃)制得的生物炭上,考察极性和非极性有机污染物萘和1-萘酚在原始和腐殖酸负载生物炭上的吸附动力学,分别应用拟一级、拟二级和双室一级3种动力学模型对实验数据进行拟合.结果表明,拟二级和双室一级动力学模型均能较好地描述动力学吸附过程.腐殖酸负载对生物炭上萘和1-萘酚的吸附动力学有显著影响,使得平衡吸附量(Q_e)下降,而表观吸附速率提高.致密的芳香碳组分和纳米级孔隙主要对萘和1-萘酚在生物炭上的慢吸附单元起作用,腐殖酸负载降低了生物炭的芳香化程度和孔隙度,慢吸附对总吸附的贡献(f_slow)降低.生物炭内部有机碳的致密性降低,使得萘和1-萘酚分子容易扩散进入生物炭颗粒内部,加之表面积和孔隙度减少,缩短吸附平衡时间,两种化合物的慢吸附速率常数(k_slow)均提高.负载腐殖酸后,两种化合物的快吸附速率常数(k_fast)的变化却不同.腐殖酸负载向生物炭表面引入...     

腐殖酸对As(V)在覆铁砂介质中吸附行为的影响

对腐殖酸(HA)进行了成分分析及红外表征,并从HA浓度、pH值、As(Ⅴ)初始浓度等方面,研究了HA对As(Ⅴ)在覆铁砂介质中吸附行为的影响.结果表明,随着HA浓度的升高,总砷去除率逐渐降低.当HA浓度增加到25mg.l-1时,与不存在HA条件下相比,总砷去除率降低了12%左右.溶液pH值影响As(Ⅴ)的去除,pH值从6升高到8时,总砷去除率从52.1%降到了39%.其中的作用机理主要是HA与As(Ⅴ)在覆铁砂表面形成竞争吸附,HA争夺了As(Ⅴ)的吸附点位.此外,HA与Fe(Ⅲ)的络合作用也是导致覆铁砂对砷的去除率降低的一个重要原因.     

The role of soil humic and fulvic acid in the sorption of endosulfan (alpha and beta)

The sorption behaviour of alpha- and beta-endosulfan in soil organic matter was investigated using standard soil humic acid (HA) and soil fulvic acid (FA) with a modified solubility enhancement method and a dialysis bag technique. For HA, all the experiments were conducted at an ionic strength of 0.001 mol/L, in both the presence and absence of calcium and at an ionic strength of 0.01 mol/L. For FA, the experiments were conducted at two ionic strengths: 0.001 mol/L (with calcium) and 0.01 mol/L. This study is the first to describe the striking differences in the sorption behaviours of the two stereoisomers of endosulfan in HA and in FA. The sorption coefficients of alpha-endosulfan in HA and FA were significantly higher than those of beta-endosulfan. Beta-endosulfan has comparable sorption coefficients (1.5–5.4 L/g) in HA and in FA. Ionic strength and the presence of calcium have no significant effect on the sorption of beta-endosulfan in HA. However, calcium can significantly (p=0.01) enhance the solubility of alpha-endosulfan in HA. Changes in ionic strength by one order of magnitude also affect the solubility of alpha-endosulfan in HA. The sorption coefficients of alpha-endosulfan in HA (10–36 L/g) were greater than those in FA (9–14 L/g). The chirality of the alpha-isomer was hypothesised to be the primary reason behind its higher sorption in soil organic matter relative to the beta-isomer. In the presence of dissolved HA and FA found in natural soil environments, solubility of endosulfan can be increased by five times than the aqueous solubility of endosulfan without HA and FA.     

中国土壤与沉积物中邻苯二甲酸酯污染水平及其吸附研究进展

邻苯二甲酸酯（PAEs）是一类重要的环境激素化合物,具有致畸性、致癌性、致突变性及生殖毒性的特点。在环境中普遍存在,对人体及生态环境的威胁极大,已经引起了人们广泛的关注。吸附作用是影响污染物在土壤及沉积物环境中迁移转化的关键因素之一。分析了近年来我国土壤及沉积物中PAEs的污染现状,归纳了影响PAEs吸附过程的主要因素。我国与世界其他各国的土壤及沉积物的PAEs主要污染组分较为一致,但PAEs污染相对严重。土壤有机质及粘土矿物对PAEs的吸附影响成为了学术界的研究热点。有机质中的腐殖质对PAEs的吸附起着决定作用;腐殖质由胡敏酸、富里酸及胡敏素,部分含有碳黑组成,各组成对PAEs的吸附影响大小不一,相应的吸附机理还有待于深入的研究,而且土壤与沉积物中的溶解性有机物（DOM）对PAEs的吸附双重影响认识还不够。在有机质含量低的土壤中,粘土矿物对PAEs的吸附起着主要作用,然而PAEs的吸附与粘土矿物类型及其表面电场的关系、是否能与水分子竞争表面电场等问题还不甚清楚,需要进一步探索。今后将引入并开发先进的分析测试技术,从土壤及沉积物的有机质组成及微观结构研究其对PAEs的吸附机理。     

毒死蜱对土壤蔗糖酶活性的影响

采用模拟方法探讨了毒死蜱污染土壤酶活性的变化规律。结果表明，有机质含量高的土壤，毒死蜱对土壤蔗糖酶具有明显的抑制作用，在酸性和中性条件下，酶活性的抑制幅度较大，在试验所设的培养时间内，毒死蜱对蔗糖酶活性的抑制总的变化趋势呈现先激活后抑制。建议对于有机质含量较高的土壤，采用蔗糖酶活性作为表征土壤毒死蜱污染程度的监测指标。     

环丙氨嗪在Aldrich胡敏酸中吸附-解吸特征的研究

采用批平衡法,研究了不同温度下环丙氨嗪在Aldrich胡敏酸中的吸附与解吸特征。结果表明：环丙氨嗪吸附和解吸过程都包含极快速、快速和缓慢阶段。伪二级动力学方程能较好地描述不同温度下环丙氨嗪的吸附动力学特性,表明吸附速率决定于胡敏酸表面吸附位点的可用度,而不是溶液中环丙氨嗪的浓度。环丙氨嗪在极快速吸附阶段的吸附速率随温度的升高而增大,但平衡时的吸附量却随温度的增加而降低。吸附等温线和解吸曲线符合Langmuir方程和Freundlich方程。环丙氨嗪在胡敏酸上的解吸速率小于吸附速率,表明存在滞后效应。吸附焓变、熵变和自由能都为负值,表明环丙氨嗪在胡敏酸上的吸附是一个自发、熵减小的放热过程。-Go〈40 kJ.mol^-1表明环丙氨嗪在胡敏酸表面以物理吸附为主。     

水体环境中天然有机质腐殖酸研究进展

腐殖酸作为一种资源广泛存在于自然界中,它是影响环境生态平衡的重要因素,也是潜在的、可大力开发和综合利用的有机资源。腐殖酸类物质具有多种活性官能团,具有酸性、亲水性、界面活性、阳离子交换能力、络合作用及吸附分散能力。腐殖酸概念、理论出现了重大突破,已从传统腐殖酸重点或仅研究腐殖酸自身发生中的物质流动、能量转化规律,同时着眼研究腐殖酸与土壤、水体和生物多界面的环境过程和机理。文章主要以水环境为例,天然有机质研究历史、化学结构,对环境污染物效应和去除技术等几个方面的研究进展进行了简要的总结;对现代腐殖酸的研究趋势进行了展望。     

The influences of different organic fractions in refuse on the sorption and bioavailability of dibutyl phthalate

The structure and composition of the organic matter in landfilled refuse might have an influence on the migration and transformation of dibutyl phthalate (DBP). Humic acid (HA) and humin (HU) were separated from aged-refuse to determine the influences of different organic fractions in the refuse on the sorption and bioavailability of DBP. The sorption kinetics and isotherms for the sorption of DBP to HA, HU, and whole refuse were determined. The results showed that the sorption constants (K) and nonlinearities decreased in the order HU?>?whole refuse?>?HA. The HA had lower K values than did the other refuse fractions, and it retarded the biodegradation of DBP over a short degradation period (48?h). Increasing the amount of HA present caused the amount of DBP that was biodegraded to decrease significantly, 81.3% of the DBP sorbed to HA being degraded in the original experiments after 48?h but 21.8% of the DBP being degraded when three times as much HA was used. Similar results were not observed when the amount of HU used was changed. These findings suggest that HA plays an important role in the biodegradation of DBP adsorbed by refuse.     

Application of ultra-sonication,acid precipitation and membrane filtration for co-recovery of protein and humic acid from sewage sludge

A novel method was applied to co-recover proteins and humic acid from the dewatered sewage sludge for liquid fertilizer and animal feed. The proteins in sewage sludge were first extracted using the processes of ultra-sonication and acid precipitation, and then the humic acid was recovered via membrane filtration. The extraction efficiency was 125.9 mg humic acid?g⁻¹VSS volatile suspended solids (VSS) and 123.9 mg proteins?g⁻¹ VSS at the optimal ultrasonic density of 1.5 W?mL⁻¹. FT-IR spectrum results indicated that the recovered proteins and humic acid showed similar chemical characteristic to the natural proteins and humic acid. The acidic solution (pH 2) could be recycled and used more than 10 times during the co-recovery processes. In addition, the dewatered sludge could be easily biodegraded when the humic acid and proteins are extracted, which was essential for further utilization. These findings are of great significance for recovering valuable nutrient from sewage sludge.     

Abiotic association of phthalic acid esters with humic acid of a sludge landfill

The abiotic association between phthalic acid esters (PAEs) and humic substances (HS) in sludge landfill plays an important role in the fate and stability of PAEs. An equilibrium dialysis combined with ¹⁴C-labeling was used to study the abiotic association of two abundant PAEs (diethyl phthalate and di-n-butyl phthalate) with humic acid (HA) isolated from a sludge landfill with different stabilization times and different molecular weights. Elemental analysis and Fourier Transform Infrared Spectrophotometer (FTIR) suggested that high K _A value of HA was related to the high aromatic content and large molecular weight of HA. The results indicated that the association strength of PAEs with HA depended on both the properties of the PAEs and the characteristics of HA. The K _A values of the association were strongly dependent on solution pH, and decreased dramatically as the pH was increased from 3.0 to 9.0. The results suggested that nonspecific hydrophobic interaction between PAEs and HA was the main contributor to the association of the PAEs with HA. The interactive hydrogen-bonds between the HA and the PAEs molecules may also be involved in the association.     

Sorption of cadmium(II) and copper(II) by soil humic acids: temperature effects and sorption heterogeneity

Sorption by humic acids is known to modify the bioavailability and toxicity of metals in soils and aquatic systems. The sorption of cadmium(II) and copper(II) to two soil humic acids was measured at pH 6.0 using ion-selective electrode potentiometric titration at different temperatures. Sorption reactions were studied with all components in aqueous solution, or with the humates in suspension. Adsorption reactions were described using a multiple site-binding model, and a model assuming a continuous log-normal distribution of adsorption constants. Adsorption of Cu²⁺ was more favourable than adsorption of Cd²⁺. The log-normal distribution model provided the closest fit to observations and allowed parameterisation of adsorption data using a mean adsorption constant (log K _μ). Sorption of Cd²⁺ to dissolved humic acids increased slightly in extent and sorption affinity with increasing temperature, but the effect was small (log K _μ 2.96–3.15). A slightly greater temperature effect occurred for sorption of Cd²⁺ to solid-phase humic acids (log K _μ 1.30–2.08). Sorption of copper(II) to both aqueous- and colloidal-phase humates showed more pronounced temperature dependence, with extent of sorption, and sorption affinity, increasing with increasing temperature (log K _μ 3.4–4.9 in solution and 1.4–4.5 in suspension). The weaker adsorption of Cd²⁺ than Cu²⁺, and smaller temperature effects for dissolved humates than suspended humates, suggested that the observed temperature effects had a kinetic, rather than thermodynamic, origin. For any metal-to-ligand ratio, free metal ion concentration, and by inference metal bioavailability, decreased with increasing temperature. The consistency of the data with kinetic rather than thermodynamic control of metal bioavailability suggests that equilibrium modelling approaches to estimating bioavailability may be insufficient.     

Removal of Cu（ll） ions from aqueous solution by activated carbon impregnated with humic acid

Humic acid （HA） was impregnated onto powdered activated carbon to improve its Cu（II） adsorption capability. The optimum pH value for Cu（II） removal was 6. The maximum adsorption capacity of HAimpregnated activated carbon was up to 5.98mg.g-1, which is five times the capacity of virgin activated carbon. The adsorption processes were rapid and accompanied by changes in pH. In using a linear method, it was determined that the equilibrium experimental data were better represented by the Langmuir isotherm than by the Freundlich isotherm. Surface charges and surface functional groups were studied through zeta potential and FTIR measurements to explain the mechanism behind the humicacid modification that enhanced the Cu（II） adsorption capacity of activated carbon.