焦化厂土壤中PAHs的热脱附行为及其对土壤性质的影响

采用滚筒式间接加热设备,在50~450℃加热温度和30 min停留时间实验条件下,测试了焦化厂污染场地低含量(S1)和高含量(S2)PAHs污染土壤中16种PAHs的热脱附效率和残留量的变化,并初步分析了热脱附处理对土壤有机碳(TOC)、可溶性有机碳(DOC)、比表面积(SA)和粒径分布的影响,结果表明:加热温度、污染物含量和污染物分子量对PAHs的脱附效率均存在极显著影响(p0.01),其中加热温度影响程度最大。S1和S2土壤中各类PAHs在加热温度达到其熔点附近开始有效脱附,LPAHs(低分子量PAHs)与HPAHs(高分子量PAHs)之间的热脱附效率仅在不超过300℃(S1土壤)和400℃(S2土壤)加热条件下存在明显差别。土壤中各类PAHs的脱附与其有效态密切相关,S1和S2土壤中有效态PAHs分别在200~250℃和250~300℃加热条件下几乎全部脱附。450℃加热温度条件下,S1和S2土壤中∑PAHs(总PAHs)脱附效率能够达到91.3%和98.4%,其中8种目标PAHs的含量范围分别为0.07~0.71 mg·kg-1和0.26~40.20 mg·kg-1,土壤中部分PAHs仍超过相应的北京市《场地土壤环境风险评价筛选值》住宅用地筛选值;450℃加热温度下,S1和S2土壤中TOC含量分别下降51.4%(p0.05)和23.1%(p0.05),S1和S2土壤中DOC变化趋势相反,SA的下降、较粗颗粒比例略有增加和电镜扫描中土壤颗粒团聚现象相吻合。     

异位热脱附修复技术对高浓度多环芳烃污染土壤的修复应用实例

以上海市某地块高浓度多环芳烃污染土壤修复工程为实例,通过实验室小试和现场中试确定多环芳烃污染土壤热脱附修复加热温度和时间工艺参数,并对修复过程进行了详细描述.实验证明,在加热300℃以上且加热时间在1h以上条件下,5种目标污染物苯并(a)蒽、苯并(b)荧蒽、苯并(a)芘、茚并(1,2,3-cd)芘、二苯并(a,h)蒽能...     

某炼铁厂汞和多环芳烃复合污染土壤热脱附试验研究

以重庆市某炼铁厂地块复合污染土壤为试样,采用真空管式电阻炉进行热脱附试验,探究复合污染土壤中汞和多环芳烃在不同脱附温度和时间下的脱附效果。结果表明：(1)土壤样品中的汞多以难降解有机质及某些硫化物结合态、残渣态或晶格态等形式存在;(2)汞含量较低初始浓度(10～20 mg/kg)和较高初始浓度(20～40 mg/kg)的土样脱附温度宜分别不低于400℃和450℃;(3)低浓度多环芳烃(超标倍数≤5)、中等浓度多环芳烃(5<超标倍数<50)和高浓度多环芳烃(超标倍数≥50)的试样,脱附温度宜分别设置为400℃、500℃和550℃;(4)对汞和多环芳烃复合污染土壤的脱附温度选择关键取决于多环芳烃;(5)脱附温度相比脱附时间对污染物脱附效果的影响更大。     

原位热脱附土壤修复技术的关键影响因素研究

为探究原位热脱附修复技术的关键影响因素,以硝基苯和萘为目标污染物,就加热时间、加热温度、土壤含水率、污染物初始浓度、土壤类型等因素对热脱附去除效率的影响开展研究。结果表明,加热时间、加热温度、对污染物的热脱附去除效率具有重要影响,土壤含水率对去除效率有一定影响,而在加热时间较长的情况下,初始浓度和土壤类型对污染去除效率影响较小。     

有机污染土壤原位热脱附及尾气处理研究进展

详细介绍了原位热脱附技术(ISTD)的原理、特点以及技术分类,并对其进行评价和总结;分析了热脱附温度、停留时间等因素对热脱附脱除效率的影响;讨论了回收型和破坏型2种类型的热脱附尾气处理技术。原位热脱附技术由于修复周期短、效率高等优点被广泛使用,未来或可向多种修复技术联合修复的方向发展。     

石油污染土壤热脱附结焦机理及结焦特性综述

结焦问题一直是热脱附处理石油污染土壤亟待解决的问题,解决结焦问题能够提高热脱附设备的处理效率、降低处理成本以及延长设备使用寿命。总结了结焦机理的三种假设：相分离机理、自由基机理、碳正离子机理和金属催化机理。吸附结焦特性主要总结了工艺参数和原料性质两个方面对结焦的影响。工艺参数包括反应温度、油气停留时间和停留温度三个方面;原料性质包括原油性质、催化剂性质和反应物浓度三个方面。以期为热脱附结焦问题的研究提供思路。     

热脱附处理技术在石油污染土壤中的研究进展

随着我国工业化的发展,作为工业命脉的石油工业不断壮大,石油产量的与日俱增为我国带来了巨大的经济利益,同时也造成了土壤与水的严重污染。石油污染具有危害性大、周期长等特点,已成为现代环境科学亟待解决的问题。介绍了石油污染土壤的特性与危害,综述了传统石油污染修复技术,总结了热脱附处理技术的工艺流程及其优势,并分析讨论了热脱附技术的影响因素与亟待解决的技术问题。最后展望了未来热脱附处理技术在石油污染土壤治理方面的研究方向及目标。     

异位热脱附技术在农药污染土壤的应用研究

我国是农药生产和使用大国,随着城市产业结构调整升级,在许多城市遗留了大量因企业关闭、搬迁遗留下的高浓度高毒性复合污染场地,涉及有机氯类农药污染、有机磷类农药污染等,给场地及周边生态环境和人体健康带来了严重风险隐患。文章以异位热脱附技术修复某农药厂污染土壤为例,通过中试研究影响异位热脱附效率的工艺参数。结果表明,加热温度为400℃,有效停留时间为20 min,水分≤20%,粒径≤30 mm时,土壤中α-六六六等污染物脱附率均在99.5%及以上。同时,可为后续大规模工程实施提出了技术参考。     

焦化厂土壤中PAHs的累积、垂向分布特征及来源分析

引言多环芳烃(polycyclic aromatic hydrocarbons,PAHs)在环境中普遍存在,由于具有强烈的诱变、致癌和致畸作用而受到越来越多的关注。以煤为主要原料的焦化行业,是环境中人类活动产生PAHs的主要来源之一,其各个生产车间内化石燃料的不完全燃烧及焦油、煤气等化工产品的加工过程都可能导致PAHs的排放。土壤是PAHs累积和迁移的重要介质,环境中的PAHs可由大气     

聚丙烯酰胺在黑土上的吸附解吸特性研究

采用静态吸附法研究了聚丙烯酰胺在黑土上的吸附行为,考查了不同吸附时间对土壤吸附量的影响,得出了聚丙烯酰胺在土壤上的吸附等温线。并且研究了聚丙烯酰胺在黑土上的解吸行为,探讨了振荡时间、液固质量比、温度、pH值对黑土中聚丙烯酰胺解吸的影响。结果表明,聚丙烯酰胺在黑土上的吸附等温线符合Langmu ir吸附模式,饱和吸附质量比为1.17 mg/g,聚丙烯酰胺在土壤上有很强的吸附亲合力,在实验条件下,最大解吸量仅为总量的25%。     

热脱附污染土壤制备水泥活性混合材的研究

为了解决热脱附污染土壤离场消纳途径少、消纳量小、附加值低的问题,提高其资源利用价值,本文研究了不同温度下热脱附的污染土壤的pH值、活性指数、矿物组成,并与石灰石粉进行复合,解决标准稠度用水量高的问题.结果 表明,随着温度升高,热脱附污染土壤的pH值由7.90增大到12.85,活性指数则先增大后减小,伊利石、方解石和钾长...     

黑腐酸的改性及其对土壤中多环芳烃的洗脱作用

以黑腐酸为原料,进行烷基化反应和磺甲基化反应,得到改性黑腐酸MHA12、MHA16和MHA18。用IR测定了改性物的结构,通过测定不同浓度下改性黑腐酸溶液的表面张力得到改性黑腐酸的临界胶团浓度CMC,并测定了MHA12、MHA16、MHA18对PAHs污染土壤中萘、菲、荧蒽、芘的洗脱效率。结果表明：黑腐酸经过改性后引入了烷基基团和磺甲基基团,具有较好的水溶性和表面活性,MHA12、MHA16、MHA18的临界胶团浓度分别为3.12 g/L、2.78 g/L、2.70 g/L。当MHA溶液浓度超过临界胶团浓度时,MHA12、MHA16和MHA18对萘、菲、荧蒽、芘都具有良好的洗脱能力,可用于多环芳烃污染土壤的修复。     

A study of interactions between soil fractions and PAH compounds in thermal desorption of contaminated soils

The interactions between three polynuclear aromatic hydrocarbons (PAHs), namely fluorene, naphthalene and anthracene, and three fractions of a soil, namely fulvic acid (FA), humic acid (HA) and humin/inorganic fractions, were studied experimentally. Prepared PAH + soil fraction binary mixtures, with PAH concentrations ranging over 0.8–7 mass%, were tested using a differential scanning calorimeter (DSC) over a temperature range of 20?390°C. The DSC thermograms for the PAH + HA mixtures showed distinctly different characteristics compared to mixtures with the other two soil fractions, where the endothermic peak for the vaporization of the PAH was absent. With the aid of vapour-liquid flash calculations, the lack of the boiling point peak is interpreted to be due to the liquid-phase miscibility of the PAHs and the HA fraction. Implications of the DSC results on the design and performance of the thermal desorption process are discussed.     

焦化厂污染土壤中多环芳烃降解菌群解析

以苯并[a]芘、苯并[a]蒽、苯并[b]荧蒽、苯并[k]荧蒽、茚并[1,2,3-cd]芘5种较难降解的多环芳烃为碳源和能源,采用富集培养的方法从焦化厂污染的土壤中筛选分离得到50株PAHs降解菌。通过对其16S rRNA基因序列分析,将这些PAHs降解菌分为15个种群,分别属于Sphingomonas(鞘氨醇单胞菌属)、Methylobacterium(甲基杆菌属)、Burkholderia(伯克霍尔德氏菌属)、Rhodococcus(红球菌属)、Bradyrhizobium(慢生根瘤菌属)、Phyllobacterium(叶杆菌属)、Chryseobacterium(金黄杆菌属)、Microbaterium(微杆菌属)8个属,其中优势菌为鞘氨醇单胞菌属。纯菌株降解能力测试表明,培养12 d后,菌株3-6-12降解效果要优于其他菌株,对苯并[a]蒽、苯并[a]芘、苯并[b]荧蒽、苯并[k]荧蒽、茚并[1,2,3-cd]芘的降解率分别可达39.64%、33.52%、38.57%、25.37%、31.17%。实验结果可为多环芳烃污染土壤的生物修复提供高效的降解菌源。     

The Impact of PAHs Contamination on the Physicochemical Properties and Microbiological Activity of Industrial Soils

The aim of this article is the study of the potential relationships between PAHs contamination, physicochemical parameters, and microbial activity in industrial soils. The research was based on two series of measurements. The first was conducted in June 2013 and the second in November 2013. Samples used in study were collected from the area of fuel handling and a loading station, located in the Silesia region of Poland. All collected samples were characterized by the following analytical procedures: PAHs content analysis, the basic physical and chemical parameters determinations (pH, CEC, humic acids content, TC, TN, TP) and microbial activity analysis. The obtained results were also subjected to statistical analysis, based on the Pearson's correlation coefficient calculations.

Results collected during described above procedure show that: the PAHs content was highly positively correlated with C and N contents (p < 0.001) and moderately correlated with humic acids and P contents (p < 0.01). This phenomenon confirms the thesis that the increase of soil organic matter content promotes accumulation of hydrophobic organic compounds such as PAHs. Microbiological analysis shows that bacteria from the mesophilic group are most resistant to PAHs contamination. This information indicates that the organisms belonging to this group should be considered as potentially useful in the soil bioremediation processes.     

2,4-二氯苯酚在黄土性土壤中的吸附与解吸

采用静态与动态实验相结合的方法,研究了2,4-二氯苯酚在黄土性土壤中的吸附和解吸规律,测定吸附动力学和吸附热力学曲线,获得吸附热力学模型。研究表明,2,4-二氯苯酚在黄土性土壤中吸附等温线可用Freundlich和Langmuir方程描述,其中q0描述饱和吸附量,由Langmuir吸附等温式拟合数据可以看出:TS-2土的饱和吸附量大于TM-1土(这是因为2,4-二氯苯酚在土壤中的吸附量与土壤中有机质的含量密切相关);由Freundlich吸附等温式拟合得到的常数,1/n均1,证明是优惠吸附;根据吸附符合Langmuir方程,说明在土壤表面,2,4-二氯苯酚为单分子层吸附;吸附-解吸具有一定的可逆性,黄土性土壤对2,4-二氯苯酚的吸附能力不强,2,4-二氯苯酚极易穿透土壤,污染地下水。     

载气流量及升温速率对污染土壤中多氯联苯热脱附的影响

利用小型管式炉进行了载气流量和升温速率对多氯联苯污染土壤的热脱附过程影响的实验研究。结果表明流量的增大对多氯联苯含量和毒性当量的去除效率影响不大,载气流量小于400 ml·min^-1时,气相中的脱附量明显增大,载气流量大于400 ml·min^-1则脱附量变化较小,而多氯联苯的毒性当量则随着载气流量增大呈线性增加趋势。实验结果还表明污染土壤中多氯联苯变化速率与升温速率呈明显的正线性相关,随着升温速率增加,污染土壤中多氯联苯去除效率总体呈上升趋势,毒性当量去除效率降低。总体结果分析可以看到升温速率越大,总体效果也越好。污染土壤经热脱附处理后气固相的二 英毒性当量则有不同程度提升,尤其气相内检测到了大量多氯二苯并呋喃生成。     

热解吸还原土的资源化利用研究进展

污油泥的污染特性对环境产生了深远影响,热解吸处理技术是当前较为成熟的技术,处理后的产物进行综合利用,降低对环境的危害。对热解吸技术进行简要阐述,对热解吸处理后的还原土资源化利用现状进行综述和介绍,为后续处置或利用提供一定的借鉴意义。     

Oilseed volatile analysis by supercritical fluid and thermal desorption methods

A knowledge of the volatile components present in an oil sample can provide important information relative to supercritical fluid extraction (SFE) process design, the current oxidative state of the oil, as well as the concentration and presence of important flavor volatiles in the oil. Volatile compounds from supercritical fluid-extracted oils were analyzed by headspace gas chromatography (GC) methods to determine if there were differences in the volatile profiles when two different methods of desorption were used. Canola, corn, soybean and sunflower seeds were extracted with supercritical carbon dioxide at 8000 psi and 50°C. Tenax porous polymer traps, attached at the exhaust port of the SFE apparatus, were utilized to collect the volatile components during the extractions. The volatile compounds on the Tenax trap were desorbed onto a GC column by both thermal and supercritical fluid techniques. Desorption temperature for the thermal method was 150°C, while conditions for the SFE technique were 50°C and 2000 psi. The lower-boiling volatiles from each oilseed were greater when desorbed by thermal means from the Tenax than by SFE; however, SFE desorbed the highermolecular weight compounds that were not removed by the thermal desorption method. Hexanal tended to be desorbed in comparable amounts by both methods. The SFE-based desorption technique provides a unique analysis method for the determination of both volatile and semivolatile compounds, as well as executing desorption under nonoxidative, low-temperature conditions that do not contribute to the degradation of lipid components.