一种基于钴的丝网印刷磷酸盐传感器研究

采用丝网印刷技术制备用于水中磷酸盐检测的传感器,其中,掺有钴粉的碳浆为工作电极,银/氯化银浆为参比电极.在25℃下,对于用pH为4.0邻苯二甲酸氢钾(KHP)缓冲溶液配制的浓度梯度为1×10-5~0.1mol/L的KH2PO4溶液,钴碳比为1:7磷酸盐丝网印刷电极有良好的能斯特响应,响应斜率为-41.63mV/decade,检测限为5×10-6mol/L,响应时间为60s,稳定性较好.丝网印刷电极的重现性很好,测量同一溶液, 同一钴碳比的丝网印刷电极的相对误差小于1%,不同钴碳比的丝网印刷电极的相对误差小于3.5%.     

线路板粉末风选过程气固两相流模拟及实验

针对线路板破碎粉末的特点,提出了一种通过风力分选实现废旧线路板中金属和非金属分离的方法.分别采用RNG k-ε模型、颗粒轨道模型模拟气流场和固体颗粒,模拟结果显示风选器腔体处于旋风状态,风压随着风选器半径和高度的增加而升高,至风选器高度为1.2m附近达到峰值.开展线路板粉末风选实验,通过模拟分析和实验分别得到不同粒径、不同叶轮转速下的优化工艺参数,结果表明粒级对实验结果的影响最大,当线路板粉末粒径为0.125~0.212mm、叶轮转速为200r/min时,金属回收率最高达到96.5%.最后进行分选效果的实验-模拟对比分析,验证了模拟的有效性及分选方案的可行性.     

Partitioning of polybrominated diphenyl ether (PBDE) congeners in human blood and milk

Polybrominated diphenyl ethers (PBDEs) are brominated flame retardants (BFRs) which have recently been detected in human blood and milk in the USA, and presently these PBDE levels are found to be the highest globally. On a population basis, individual blood and individual milk analyses show similar congener patterns and levels. Until now, there has not been a study comparing PBDE levels in milk and blood of the same individuals. This study is the first to report these levels for PBDEs, though partitioning between blood and milk has been done previously for dioxins and polychlorinated biphenyls (PCBs). Twelve congeners in 11 nursing mothers’ blood and milk were found and the data describe partitioning ratios between blood and milk. The data suggest it may be easier for smaller, less brominated congeners to move from blood to milk.     

Organochlorine residues in maternal milk from inhabitants of the Thohoyandou area,South Africa

The presence of organochlorine compounds (OC) such as DDT and their metabolites in the environment have created a significant environmental concern over the years due to adverse effects. Consequently, DDT has been banned in many countries. However, it is still used in some countries including South Africa, particularly for vector-borne disease eradication programmes. Since the presence of DDT and its metabolites may provide an indication of the general exposure and use of these compounds, there was a need for such a study. Human breast milk samples (n = 30) were collected from mothers within the age range of 19–40 years from the Thohoyandou area, South Africa. The liquid–liquid extraction method was used to extract DDT and its metabolites from the samples. The crude extracts were subjected to column chromatography for measurements of OC levels. The concentration ranges of the contaminants were as follows: not detected (ND) to1770 ng g^?1 (2,4′-DDE); ND to 3977 ng g^?1 (4,4′-DDE); ND to 3250 ng g^?1 (2,4′-DDD); ND to 2580 ng g^?1 (4,4′-DDD) and ND to 2847 ng g^?1 (4,4′-DDT). The mean ΣDDE, ΣDDD and ΣDDT obtained from the villages were 1180 ng g^?1, 830 ng g^?1 and 690 ng g^?1, respectively. The total DDT ranged from 820–7473 ng g^?1. The estimated daily intake varied from 260 to 4696 ng g^?1, ND-10551 ng g^?1 and ND-4237 ng g^?1 for DDE, DDD and DDT, respectively. These values are significantly higher than the FAO/WHO acceptable daily intake (ADI) of 20 ng g^?1. The ΣDDT was found to decrease with increasing age of the mothers. The observed high levels of DDE compared to DDT indicated chronic exposure of the mothers to DDT, which is metabolized to DDE and retained in the body.     

Lifestyle and polybrominated diphenyl ethers in human milk in the United States: A pilot study

Polybrominated diphenyl ethers (PBDE) are a class of brominated flame retardants with some congeners having the ability to accumulate in body lipids. The incorporation of PBDE in consumer products found primarily in the indoor environment suggests that routes of exposure include inhalation of indoor air and contact with indoor dust. The purpose of this study was to test the hypothesis that lifestyle factors, and in particular the proximity and use of products likely to contain PBDE in the indoor environment, are primarily responsible for levels of PBDE found in human milk. Human milk samples were taken from two populations of lactating women in the same geographic region of the United States: one “typical” of US suburban lifestyle, and the other practicing a traditional Amish lifestyle, which excludes many modern amenities containing PBDE, such as computers and televisions. For a subset of the cohort, persistent organic pesticides and polychlorinated biphenyls (PCB) were also measured in human milk samples. Despite the small number of participants, there is evidence suggestive of Amish women having lower PBDE concentrations in their milk. In addition, the nonsignificant differences in levels of PCBs and pesticides between the two groups of women as compared to the significant differences in levels of PBDE suggest an important route of exposure for PBDE other than diet. Information prepared for study participants is provided to initiate a dialogue on how to best communicate biomonitoring findings to study participants and to the public in general.     

Organochlorine pesticide and polychlorinated biphenyl residues in human milk from Tabriz,Iran

Human breast milk samples, collected during April 2007 in Tabriz, Iran, were analyzed for organochlorine (OC) pesticides, such as dichlorodiphenyltrichloroethane (DDT) and its metabolites, hexachlorobenzene (HCB), α, β, and γ-hexachlorocycloexane (HCH) isomers and six polychlorinated biphenyls (PCB) congeners (IUPAC Nos. 28, 52, 101, 138, 153, and 180). Organochlorine pesticides and OCB were both prevalent in the samples of human breast milk. Average concentrations of HCB, DDT, HCH, and PCB were 1020, 1930, 1660, and 690 ng g^?1 lipid weight, respectively. A positive correlation was observed between concentration of OC in human breast milk and mothers age with primiparae. Women having higher OC concentrations than multiparae women suggests that these parameters influence the OC burden in lactating women. The estimated tolerable daily intakes (TDIs) of HCH, HCB and PCB solely from human breast milk were 100, 46, and 43% of samples, respectively, exceeding guideline thresholds given as TDI proposed by Health Canada. Although high daily intakes may raise concerns for possible adverse effects of OC, women in Tabriz are recommended to breastfeed due to the numerous advantages for mother and child.     

Organochlorine insecticide residues in Egyptian mothers’ milk

Two hundred ninety‐two mother's milk samples were collected during 1994 from ten Egyptian governorates representing rural, metropolitan, and newly reclaimed desert areas. The samples were analyzed for 14 organochlorine insecticides and metabolites using electron capture gas chromatography and confirmed by gas chromatography/mass spectrometry (GC/MS). The overall samples average showed that the most abundant organochlorine insecticide residues were p,p'‐DDE, α‐endosulfan, β‐HCH and, p,p’‐DDT. Residues in the range of not detectable to less than 14μg/l whole milk were recorded for α‐HCH, heptachlor, heptachlor epoxide, aldrin, dieldrin, endrin endrin aldehyde and p,p'‐DDD. The percentage of samples exceeding the acceptable daily intake for children (ADIs) set by the FAO/WHO ranged from 19% to 44% in all governorates included in the study except the governorate of Minia in which only 2.6% of the samples exceeded the ADI values. The insecticides exceeding ADI values are mostly heptachlor and heptaclor epoxide (ADI = 3.12 μg/1 whole milk).     

Cement-based solidification/stabilization of contaminated soils by nitrobenzene

The cement-based solidification/stabilization (S/S) of nitrobenzene (NB) contaminated soils, with cement and lime as binders, sodium silicate solution and powder activated carbon (PAC) as additives, was optimized through an orthogonal experiment, and S/S efficiency was estimated by both leaching test and volatilization measurement. The leaching test results showed that the factors affecting S/S efficiency were NB concentration, cement-to-lime ratio and binder-to-soils ratio, in sequence. With increasing curing time, the leaching concentration of NB between different levels of the same factor in the orthogonal experiment decreased, and less than 9% NB leached out from the 28 d cured samples. The volatilization measurement results indicated that 0.5‰ of NB was volatilized during the mixing and curing processes for the samples without PAC in the 28 d cycle, whereas adding 2 wt% and 5 wt% PAC, with respect to the weight of contaminated soils, could reduce NB volatilization to half of its original values either during the mixing or curing process. The optimizing formula, that is, contaminated soils (dry weight):cement:lime= 100:25:25, with 5 wt% additional sodium silicate and 2 wt% additional PAC, was applied to the engineering application of NB contaminated soils. Both the leaching test results of the product and the ambient air quality monitoring results met related regulations during the treating process.     

汉麻粉体/PVDF共混膜的制备、表征及对Cu~(2+)吸附性能研究

采用浸没沉淀法,制备了汉麻粉体/PVDF混合平板膜,分别采用扫描电镜、孔隙率、机械性能测试对膜结构和性能进行表征,探究汉麻粉体对膜结构性能的影响。结果表明:膜结构为指状多孔膜,随着汉麻粉体含量的增加,从断面结构可见,脆性增加,断面整齐,指状孔明显,膜的孔径有先增大、后减小的趋势;表征结果表明膜的孔隙率有提高的趋势;承受最大载荷增加,断裂伸长率下降。汉麻粉体膜制备完成后,采用静态吸附法进行吸附试验,分别探讨了温度、粉体含量、铜离子的初始浓度对吸附效果的影响。结果表明:汉麻粉体膜对铜离子的吸附,当温度为25℃时,吸附量与吸附率最佳;随着粉体含量的增加,吸附量与吸附率先减小、后增大的趋势。初始浓度的影响较为显著,随着初始浓度的增加,吸附量与吸附率也随之增加。     

磁粉活性污泥法处理城市生活污水的反应动力学特征

磁粉活性污泥法是在传统活性污泥法中加入磁性粉末(Fe3O4)的废水生物处理方法。在最佳运行状况下,对磁粉活性污泥法基质降解动力学进行了研究。磁粉活性污泥法基质降解符合一级反应规律,利用Monod方程对试验数据进行拟合,确定了其动力学参数,半速率常数Ks、有机底物的最大比降解速率vmax分别为10.39 mg/L和0.804 d-1。