Chelant-aided enhancement of lead mobilization in residential soils

Chelation of metals is an important factor in enhancing solubility and hence, availability to plants to promote phytoremediation. We compared the effects of two chelants, namely, ethylenediaminetetraacetic acid (EDTA) and ethylenediaminedisuccinic acid (EDDS) in enhancing mobilized lead (Pb) in Pb-based paint contaminated residential soils collected from San Antonio, Texas and Baltimore, Maryland. Batch incubation studies were performed to investigate the effectiveness of the two chelants in enhancing mobilized Pb, at various concentrations and treatment durations. Over a period of 1 month, the mobilized Pb pool in the San Antonio study soils increased from 52 mg kg⁻¹ to 287 and 114 mg kg⁻¹ in the presence of 15 mM kg⁻¹ EDTA and EDDS, respectively. Stepwise linear regression analysis demonstrated that pH and organic matter content significantly affected the mobilized Pb fraction. The regression models explained a large percentage, from 83 to 99%, of the total variation in mobilized Pb concentrations.     

Processing of antifouling paint particles by Mytilus edulis

Particles of spent antifouling paint collected from a marine boatyard were ground and subsequently administered to the filter-feeding bivalve, Mytilus edulis, maintained in static aquaria. Concentrations of Cu and Zn were measured in seawater throughout a 16 h feeding phase and a 24 h depuration phase, in rejected and egested particles collected during the respective phases, and in the organisms themselves at the end of the experiments. Concentrations and distributions of Cu and Zn in processed particles indicated that M. edulis was able to ingest paint particles, regardless of whether nutritionally viable silt was present, and no mechanism of particle discrimination was evident. Enrichment of Cu and Zn in the visceral mass of individuals and in the aqueous phase during depuration supported these assertions, although elevated concentrations in other compartments of the organism (e.g. shell, gill) suggested that biotic and abiotic uptake of aqueous metal was also important.     

Leaching of hydrophobic Cu and Zn from discarded marine antifouling paint residues: Evidence for transchelation of metal pyrithiones

Leaching of Cu and Zn from a composite of discarded antifouling paint residues ([Cu] = 288 mg g⁻¹; [Zn] = 96 mg g⁻¹) into natural sea water has been studied over a period of 75 h. Total Cu and Zn were released according to a pseudo first-order reaction, with rate constants on the order of 0.3 and 2.5 (mg L⁻¹)⁻¹ h⁻¹, respectively, and final concentrations equivalent to the dissolution of about 8 and 2% of respective concentrations in the composite. Time-distributions of hydrophobic metals, determined by solid phase extraction-methanol elution, were more complex. Net release of hydrophobic Cu was greater in the absence of light than under a sequence of light-dark cycles; however, hydrophobic Zn release was not detected under the former conditions but contributed up to 50% of total aqueous Zn when light was present. These observations are interpreted in terms of the relative thermodynamic and photolytic stabilities of biocidal pyrithione complexes.     

Site environmental assessment to an old paint factory in China

High ethyl-benzene and total petroleum hydrocarbons (TPHs) were found in the soil samples and groundwater samples during a site environmental assessment for an old paint factory in the city Changchun, Jilin province of China. The target old paint plant had been in operation for near 30 years by manufacturing resin and house paint. Driving force for this study was to identify potential environmental contamination existing in this paint factory which is located next to a new resident area under construction. The assessment result would be used as baseline environmental data input for remediation plan when the factory site will be changed into potential resident area in near future. The analytical data from the soil samples from different area of the factory which had high exposure to operation showed that solid waster storage area was contaminated with high heavy metals (Cd, Pb, and Zn) and waster paint storage areas were contaminated with ethyl-benzene, xylene and C9-C30 aromatic hydrocarbon solvent. The analytical data from the groundwater samples from different area of the factory showed that resin plant area and waster paint storage areas were contaminated with high concentration of naphthalene, ethyl-benzene and xylene which exceed the reference standard. Remediation action is recommended.     

杉木短柱高温烘烤后残余承载力研究

为了研究杉木短柱在高温后残余承载力,制作了一批构件,进行了高温烘烤和轴心压缩试验.通过对试验结果进行分析,研究杉木短柱炭化速度和压缩性能变化规律,探讨烘烤温度、防火漆对杉木短柱炭化速度、残余承载力的影响.试验表明,杉木短柱炭化速度随着烘烤温度的增加而增加,高温后杉木短柱的压缩曲线分为弹塑性阶段和破坏下降阶段,当荷载达到...     

纳米隔热涂料用纳米TiO2的表面改性研究

以硅烷偶联剂为改性剂，通过实验研究了纳米TiO2有机化表面改性的影响因素。结果表明，硅烷偶联剂用量为15%、二氯甲烷作为溶剂、改性时间为2h，改性后的纳米TiO2的表面由亲水性转变为亲油性，并能较好地分散于甲苯中，能满足纳米隔热涂料的制备。     

Comparison of the substrate effect on voc emissions from water based varnish and latex paint

BACKGROUND, AIMS AND SCOPE: The building materials are recognised to be major contributors to indoor air contamination by volatile organic compounds (VOCs). The improvement of the quality of the environment within buildings is a topic of increasing research and public interest. Legislation in preparation by the European Commission may induce, in the near future, European Union Member States to solicit the industries of paints, varnishes and flooring materials for taking measures, in order to reduce the VOC emissions resulting from the use of their products. Therefore, product characterisation and information about the influence of environmental parameters on the VOC emissions are fundamental for providing the basic scientific information required to allow architects, engineers, builders, and building owners to provide a healthy environment for building occupants. On the other hand, the producers of coating building materials require this information to introduce technological alterations, when necessary, in order to improve the ecological quality of their products, and to make them more competitive. Studies of VOC emissions from wet materials, like paints and varnishes, have usually been conducted after applying the material on inert substrates, due to its non-adsorption and non-porosity properties. However, in real indoor environments, these materials are applied on substrates of a different nature. One aim of this work was to study, for the first time, the VOC emissions from a latex paint applied on concrete. The influence of the substrate (uncoated cork parquet, eucalyptus parquet without finishing and pine parquet with finishing) on the emissions of VOC from a water-based varnish was also studied. For comparison purposes, polyester film (an inert substrate) was used for both wet materials. METHODS: The specific emission rates of the major VOCs were monitored for the first 72 h of material exposure in the atmosphere of a standardized test chamber. The air samples were collected on Tenax TA and analysed using thermal desorption online with gas chromatography provided with both mass selective detection and flame ionisation detection. A double exponential model was applied to the VOC concentrations as a function of time to facilitate the interpretation of the results. RESULTS AND DISCUSSION: The varnish, which was introduced in the test chamber 23 h after the application of the last layer of material, emitted mainly glycolethers. Only primary VOCs were emitted, but their concentrations varied markedly with the nature of the substrate. The higher VOC concentrations were observed for the parquets of cork and eucalyptus, which indicated that they have a much higher porosity and, therefore, a higher power of VOC adsorption than the finished pine parquet (and polyester film). The paint was introduced in the chamber just after its application. Only primary VOCs were emitted (esters, phthalates, glycolethers and white spirit) but some compounds, like 2-(2-butoxyethoxy)ethanol and diethylphthalate, were only observed for paint/polyester, which suggested that they were irreversibly adsorbed by the paint/concrete. Compared with the inert substrate, the rate of VOC emissions was lower for concrete in the wet-stage (first hours after the paint application) but slightly higher later (dry-stage) as a consequence of desorption. CONCLUSIONS: As to varnish, the substrates without finishing, like cork and eucalyptus parquets, displayed a higher power of adsorption of VOCs than the pine parquet with finishing, probably because they have a higher porosity. As concerns paint, the total masses of VOCs emitted were lower for concrete than for polyester, indicating that concrete reduces the global VOC emissions from the latex paint. Concrete is seen to have a strong power of adsorption of VOCs. Some compounds, namely 2-(2-butoxyethoxy)ethanol, diethylphthalate and TEXANOL (this partially), were either irreversibly adsorbed by the concrete or desorbed very slowly (at undetected levels). A similar behaviour had not been reported for gypsum board, a paint substrate studied before. RECOMMENDATIONS AND OUTLOOK: The present data suggest that concrete may be a recommendable substrate for paint in an indoor environment. As the nature of the substrate conditions the rate and nature of VOC emissions from wet materials, it must be explicit when emissions from composite materials are reported, in order to allow comparisons and labelling of the product in terms of indoor air quality.     

钛石膏制备粉刷石膏的参数优化及光解室内VOCs的性能研究

VOCs是一种危害环境及人体健康的有毒有害物,已得到全社会的广泛关注。利用大宗固废钛石膏制备粉刷石膏是消纳该类废弃物的创新思路,依据国家标准及相关分析手段(XRD、SEM、GC)等研究了碱性掺合料对钛石膏制备粉刷石膏的凝结时间及强度的影响,确定缓凝剂及保水剂在石膏中的合理参数,并以此进行了光催化降解由甲醛、甲苯、二甲苯等组成的VOCs的研究。研究表明:钛石膏制备的粉刷石膏可有效去除室内VOCs(总体去除率达到80%左右)污染物。这提供了一个可行的废钛石膏利用思路。     

气相色谱质谱-内标法检测油漆中苯系物

以氯苯为内标物,采用气相色谱-质谱联用仪对油漆中苯系物的检测技术进行了研究,考察了主要苯系物的线性、回收率和精密度情况,开发出一种同时检测油漆中六种苯系物的高灵敏度方法。对样品的色谱分离条件、提取溶剂、定量方法及内标物选择等进行了优化,实现了一次进样同时定性定量检测油漆中6种苯系物。六种苯系物在1.0~500.0μg/mL范围内线性良好,各种苯系物的标准工作曲线线性相关系数0.995 4~0.999 8;在100.0~500.0μg/mL浓度范围内,加标回收率在85.01%~107.44%之间,精密度在2.58%~12.43%之间;5种苯系物组分中苯、甲苯、乙苯、间(对)二甲苯、邻二甲苯的最小检测浓度(按三倍信噪比)分别为0.01、0.002、0.05、0.05、0.05μg/mL。该方法灵敏度较高,所得数据准确,是一种检测油漆等化工品中苯及同系物含量的有效方法。     

油漆涂层老化黄变分析

汽车涂装后形成的涂层,既要具备较好的外观装饰效果,又必须具有优良的防护性能,而在实际使用过程中,常因涂层老化而发生的黄变,严重影响了其原有的性能要求。文章分析了涂层老化黄变的原因,对比分析了几种面漆的耐老化性能,并提出提高涂层耐黄变性能的措施。