Application of microwave irradiation in the removal of polychlorinated biphenyls from soil contaminated by capacitor oil

The applicability of microwave irradiation in the removal of polychlorinated biphenyls (PCBs) from the soil heavily contaminated by capacitor oil was studied. Granular activated carbon (GAC) was added into the soil as a microwave-absorbing material to rapidly increase the temperature of the reaction system. Effects of sodium hypophosphite (SHP) and iron powder (IP) as reductants on PCB removal, as well as the effects of water content in soil, microwave power and the amount of GAC added were investigated. The results indicated that in the presence of SHP and GAC, about 80% of PCBs in soil were effectively removed by 10 min microwave irradiation, and the further addition of IP could raise the average removal efficiency to a higher level, more than 95%. In the removal of PCBs with the microwave/GAC/IP/SHP system, an appropriate amount of water proved to be helpful in promoting the removal of PCBs from soil by steam distillation and in acting as a co-solvent of SHP and H-donor of IP.     

微波辐射回用活性炭对水中亚甲基蓝和Cd~(2+)去除效果的研究

考察了微波-活性炭联合处理技术对模拟染料废水中亚甲基蓝和Cd2+的去除效果。对于100 mL浓度为1 000 mg/L的亚甲基蓝溶液、活性炭用量为10 g时,新活性炭对亚甲基蓝的去除率为99.99%;采用700 W微波对吸附亚甲基蓝的活性炭辐射10 min进行再生并回用,经微波辐射再生10次后活性炭对亚甲基蓝的去除率为99.68%,未经微波作用反复使用10次的活性炭对亚甲基蓝的去除率为85.41%。结果表明:微波处理有效地减缓了活性炭吸附能力的下降速率,实现了活性炭再生和反复使用。在吸附过程中,Cd2+使活性炭对亚甲基蓝的吸附能力略有下降,而共存的亚甲基蓝则促进了活性炭对Cd2+的吸附,对新炭和再生后活性炭物理化学特性的表征证明了活性炭对亚甲基蓝的吸附为物理吸附,对Cd2+的吸附为化学吸附。     

微波辐射回用活性炭对水中亚甲基蓝和Cd2＋去除效果的研究

考察了微波-活性炭联合处理技术对模拟染料废水中亚甲基蓝和Cd2＋的去除效果。对于100 mL浓度为1 000 mg/L的亚甲基蓝溶液、活性炭用量为10 g时,新活性炭对亚甲基蓝的去除率为99.99%;采用700 W微波对吸附亚甲基蓝的活性炭辐射10 min进行再生并回用,经微波辐射再生10次后活性炭对亚甲基蓝的去除率为99.68%,未经微波作用反复使用10次的活性炭对亚甲基蓝的去除率为85.41%。结果表明：微波处理有效地减缓了活性炭吸附能力的下降速率,实现了活性炭再生和反复使用。在吸附过程中,Cd2＋使活性炭对亚甲基蓝的吸附能力略有下降,而共存的亚甲基蓝则促进了活性炭对Cd2＋的吸附,对新炭和再生后活性炭物理化学特性的表征证明了活性炭对亚甲基蓝的吸附为物理吸附,对Cd2＋的吸附为化学吸附。     

The effect of terpenes on the biodegradation of polychlorinated biphenyls by Pseudomonas stutzeri.

The effect of two terpenes, carvone and limonene, on the biodegradation of DELOR 103, a commercial mixture of polychlorinated biphenyls (PCBs), by Pseudomonas stutzeri, an isolate from long-term PCB-contaminated soil, was studied in detail. The addition of both carvone and limonene as potential inducers of the dioxygenase metabolic pathway exerted an enhancing effect on PCB biodegradation when glycerol and xylose were used as carbon sources, whereas no such effect could be determined with biphenyl and glucose as substrates. Promising biodegradation values were determined with xylose as carbon source and carvone as terpene inducer. In this system, 30-70% of the congeners were degraded in the presence of 10 mg l(-1) and 20 mg l(-1) carvone, respectively, irrespective of the used concentration, whereas only 7-37% of individual PCB congeners were eliminated from the system without terpene addition.     

Treatment of polychlorinated biphenyls in two surface soils using catalyzed H₂O₂ propagations

Two surface soils contaminated with polychlorinated biphenyls (PCBs) collected from Superfund sites in the New England region of the United States, Fletcher Paints and Merrimack Industrial Metals, were evaluated for field treatment at the bench level using catalyzed H₂O₂ propagations (CHP—modified Fenton’s reagent). The two soils were first evaluated for the potential for in situ treatment based on two criteria: (1) temperature (<40 °C after CHP reagent addition), and (2) hydrogen peroxide longevity (>24 h). In situ CHP remediation was more applicable to the Fletcher soil, while the Merrimack soil was better suited to ex situ treatment based on temperature increases and hydrogen peroxide lifetimes. Using the highest hydrogen peroxide concentrations appropriate for in situ treatment in each soil, PCB destruction was 94% in the Fletcher soil but only 48% in the Merrimack soil. However, 98% PCB destruction was achieved in the Merrimack soil using conditions more applicable to ex situ treatment (higher hydrogen peroxide concentrations with temperatures >40 °C). Analysis of degradation products by gas chromatography/mass spectroscopy showed no detectable chlorinated degradation products, suggesting that the products of PCB oxidation were rapidly dechlorinated and degraded. The results of this research document that the two PCB-contaminated soils studied can be effectively treated using aggressive CHP conditions, and that such a detailed bench study provides important information before implementing field treatment.     

Microwave Process for Volatile Organic Compound Abatement

ABSTRACT

The CHA Corporation has completed the U.S. Air Force Phase II Small Business Innovation Research program to investigate the feasibility of using a novel microwave-based process for the removal and destruction of volatile organic compounds (VOCs) in effluents from noncombustion sources, such as paint booth ventilation streams. Removal of solvents by adsorption, followed by the regeneration of saturated granular activated carbon (GAC) by microwave energy, was achieved in a single fixed-bed reactor. Microwave regeneration of the fixed-bed-saturated carbon restored the original GAC adsorption capacity. After 20 adsorption/regeneration cycles, the adsorption capacity dropped from 13.5 g methyl ethyl ketone (MEK)/100 g GAC to 12.5 g MEK/100 g GAC. During microwave regeneration of the GAC fixed bed, the concentrated desorbed paint solvent was oxidized by passing the solvent mixture through a fixed bed of an oxidation catalyst mixed with silicon carbide in a microwave reactor. A 98% oxidation efficiency was consistently achieved from the oxidation of VOCs in the microwave catalytic reactor.     

Microwave process for volatile organic compound abatement

The CHA Corporation has completed the U.S. Air Force Phase II Small Business Innovation Research program to investigate the feasibility of using a novel microwave-based process for the removal and destruction of volatile organic compounds (VOCs) in effluents from noncombustion sources, such as paint booth ventilation streams. Removal of solvents by adsorption, followed by the regeneration of saturated granular activated carbon (GAC) by microwave energy, was achieved in a single fixed-bed reactor. Microwave regeneration of the fixed-bed-saturated carbon restored the original GAC adsorption capacity. After 20 adsorption/regeneration cycles, the adsorption capacity dropped from 13.5 g methyl ethyl ketone (MEK)/100 g GAC to 12.5 g MEK/100 g GAC. During microwave regeneration of the GAC fixed bed, the concentrated desorbed paint solvent was oxidized by passing the solvent mixture through a fixed bed of an oxidation catalyst mixed with silicon carbide in a microwave reactor. A 98% oxidation efficiency was consistently achieved from the oxidation of VOCs in the microwave catalytic reactor.     

流化床微波解吸载甲苯活性炭研究

利用微波作为加热手段,采用椰壳基颗粒活性炭(GAC)为吸附剂,经吸附甲苯达饱和后进行流化床微波解吸实验.结果表明:(1)前4 min,轻微流化状态下的甲苯浓度总体小于中等流化状态;4 min后,轻微流化状态下的甲苯浓度逐渐大于中等流化状态.轻微流化状态下的甲苯解吸效果不理想,与中等流化状态有很大差距.流化床微波解吸适宜...     

A new rapid method for quantification of PCBs in transformer oil

In order to improve the efficiency and cost-effectiveness of the PCB analysis, the DMSO partition and SPE extraction were applied to clean up the PCB-contaminated transformer oils and PCB level was determined by means of the quadrupole GC/MS. The analysis data obtained from this method were compared statistically to that from the standard method.     

微波-活性炭联合作用在污染控制中的应用

近年来,微波技术被越来越多地应用于污染控制方面的研究,其中相当一部分工作是借助于微波与活性炭的相互作用,即利用活性炭在微波辐照下可快速升温的特性,获得较高反应温度,同时活性炭还具有较强的还原能力和催化作用,从而达到分解吸附在活性炭孔隙内部或与活性炭共存于同一体系中的污染物的目的。首先从活性炭在微波场中升温的角度探讨了微波辐照对活性炭的作用,并就微波活性炭联合作用在气态污染物处理、液态污染物处理、土壤污染修复以及活性炭为载体的催化剂制备等方面的研究进展进行了评述。     

Microbial reductive dechlorination of polychlorinated biphenyls in heat treated and bromoethanesulfonate treated anaerobic sediment slurries

Anaerobic reductive dechlorination of polychlorinated biphenyls (PCBs) in heat treated, bromoethanesulfonate (BES) treated, and untreated slurries of PCB-contaminated upper Hudson River sediment was investigated to better understand the microorganisms that mediate this process. Extensive meta-and para-dechlorination of Aroclor 1242 and 2,3,4-trichlorobiphenyl (2,3,4-CB) occurred in both the untreated and heat treated slurries. Heat treatment of the slurries eliminated methanogenesis, enhanced 2,3,4-CB dechlorination, and caused extensive meta- and para-dechlorination of Aroclor 1242 earlier than in untreated slurries. BES treatment (1 mM) of the slurries caused a 90% reduction in methanogenesis and inhibited metadechlorination of PCB congeners containing 2,3- and 2,5-dichlorophenyl groups. The results suggest that there are at least two distinct microbial PCB reductive dechlorination activities in PCB-contaminated upper Hudson River sediment, a meta-dechlorination activity and a para-dechlorination activity on Aroclor 1242. Both of these microbial activities are apparently not methanogenic and are resistant to or activated by heat treatment. In addition, the meta- but not the para-dechlorinating activity is inhibited by BES treatment.     

Degradation of 3,3′-iminobis-propanenitrile in aqueous solution by Fe0/GAC micro-electrolysis system

The degradation of 3,3′-iminobis-propanenitrile was investigated using the Fe⁰/GAC micro-electrolysis system. Effects of influent pH value, Fe⁰/GAC ratio and granular activated carbon (GAC) adsorption on the removal efficiency of the pollutant were studied in the Fe⁰/GAC micro-electrolysis system. The degradation of 3,3′-iminobis-propanenitrile was affected by influent pH, and a decrease of the influent pH values from 8.0 to 4.0 led to the increase of degradation efficiency. Granular activated carbon was added as cathode to form macroscopic galvanic cells between Fe⁰ and GAC and enhance the current efficiency of the Fe⁰/GAC micro-electrolysis system. The GAC could only adsorb the pollutant and provide buffer capacity for the Fe⁰/GAC micro-electrolysis system, and the macroscopic galvanic cells of the Fe⁰/GAC micro-electrolysis system played a leading role in degradation of 3,3′-iminobis-propanenitrile. With the analysis of the degradation products with GC–MS, possible reaction pathway for the degradation of 3,3′-iminobis-propanenitrile by the Fe⁰/GAC micro-electrolysis system was suggested.     

海绵铁还原耦合活性炭吸附-微波再生技术降解甲基橙

采用海绵铁(s-Fe0)还原耦合活性炭(GAC)吸附-微波(MW)再生技术降解甲基橙(MO)溶液,重点考察了s-Fe0投加量、粒径、微波功率等因素对MO去除效果的影响。结果表明,s-Fe0投加剂量为15.0 g/L、粒径为3～5 mm、超声波功率为200 W,反应1 h,MO的去除率为94.2%。其次,采用GAC吸附-MW再生技术(800 W,照射1 min)循环处理上述脱色后的MO废水。结果表明,GAC吸附可有效降低废水的生物毒性及残留的染料、TOC和总铁离子浓度,且MW辐射可有效再生吸附饱和的GAC颗粒。因此,s-Fe0还原耦合GAC吸附-MW再生技术可以有效降解MO染料,具有处理效果好、实现资源循环利用等优点。     

微波辐照载甲苯活性炭再生研究

研究在微波辐照条件下,活性炭量、微波功率、载气量、加热时间等因素对载甲苯活性炭脱附的影响,在正交实验中,各个影响因素的重要性排序为:氮气流量、活性炭量、辐照时间、微波功率,最佳的操作工况为:活性炭量9 g、载气流量300 mL/min、辐照时间120 s、微波功率500W,活性炭的脱附率在99.74%.     

微波辅助-活性炭法处理电厂EDTA锅炉清洗废水可行性研究

采用微波辅助-活性炭法处理电厂EDTA锅炉清洗废水,研究了微波辐射时间、微波功率以及再生次数对活性炭吸附能力的影响,并根据实验结果设计了工艺流程,分析了微波辅助-活性炭法处理电厂EDTA锅炉清洗废水的可行性.研究表明,微波辅助-活性炭法处理EDTA清洗废水的最佳微波辐射时间和微波功率分别为5 min和680 W,微波辐...     

活性炭-微波辐射法去除苯酚的机理研究

通过微波辐射前后水样的紫外分光扫描分析,以及微波辐射后水样中的苯酚浓度和COD浓度之间线性相关性分析表明,活性炭-微波辐射强化除酚效率的主要机理是微波使反应体系温度升高导致的活性炭加速吸附作用,而不是微波诱导催化氧化作用。通过对微波辐射前后活性炭的SEM扫描电镜分析说明,活性炭在微波场中由于“微域爆炸”导致其表面及内部孔隙结构的变化, 吸附性能得到改善,是强化苯酚去除的另一原因。 研究还表明,在较短的作用时间内,活性炭-微波辐射法的除酚效率高于常温吸附,但低于沸腾条件下的高温吸附。活性炭-微波辐射去除苯酚的规律遵循其吸附特性,温度越高,吸附反应速度越快。     

活性炭纤维对染料的吸附性能研究

研究了聚丙烯腈活性炭纤维（P－ACF）、粘胶活性炭纤维（R－ACF）和颗粒活性炭（GAC）对5种红色染料的吸附能力,通过简单的模型,算出5种染料在两种活性炭纤维上的吸附速率常数。结果表明,尽管吸附能力随染料种类不同而有一定的差别,但总体上,聚丙烯腈活性炭纤维的吸附能力略低于颗粒活性炭,而粘胶活性炭纤维的吸附能力则远远优于前两种,对染料有着较大的吸附容量和较快的吸附速率。     

微波法制备污泥活性炭研究

采用微波加热法,以污水厂剩余污泥为原料,磷酸为污泥活化剂制备污泥活性炭.微波功率、辐照时间和磷酸浓度对污泥活性炭吸附性能具有显著影响,在最佳工艺条件微波功率480 W、辐照时间315 s和磷酸浓度40%条件下制得的活性炭碘值301 mg/g,比表面积168 m2/g,污泥中重金属绝大部分被固化.与传统商品炭相比,污泥炭孔隙结构以中孔为主.利用该活性炭处理城市生活污水处理厂出水,COD去除率可达87%以上,污泥炭的吸附等温线用Langmuir等温吸附模型进行描述.     

微波修复原油污染土壤的均匀设计实验

采用均匀设计实验方法,研究了微波修复原油污染土壤时原油去除率与微波能耗、含水率和含炭率等因素的关系,并应用MATLAB编程拟合出经验公式。结果分析表明:微波能耗在0～288 kJ范围内,污染土壤的原油去除率随微波能耗线性增加;在含水率为6%、含炭率为4%、微波能耗从0增加到288 kJ时,原油去除率从0%增加至92.3%;含炭率在0%～4%范围内原油去除率与含炭率成线性关系,在微波能耗为288 kJ、含水率为6%、含炭率从0%增加到4%时,原油去除率从12.3%增加至92.3%;原油去除率与含水率成二次曲线关系且开口向下,微波修复原油污染土壤的最佳含水率为6.6%。研究结果对微波修复原油污染土壤技术的优化提供了有价值的参考。     

活性炭多维电极法去除水中腐殖酸过程与宏观动力学研究

采用活性炭多维电极法去除水中溶解态腐殖酸。实验结果表明 ,与活性炭单纯吸附法相比 ,活性炭多维电极法可显著提高对溶解态腐殖酸的去除率 ;在连续运行条件下 ,延长水力停留时间、升高槽电压、溶液偏碱性有利于腐殖酸的去除 ;高效液相色谱分析结果表明 ,电极的氧化还原作用可使有机物分子量变小或矿化 ,因而处理系统有可能延长活性炭的使用寿命