Sorption kinetics of parent and substituted PAHs for low-density polyethylene (LDPE): Determining their partition coefficients between LDPE and water (KLDPE) for passive sampling

Low-density polyethylene (LDPE) has been widely used as a sorbent for passive sampling of hydrophobic organic contaminants (HOCs) in aquatic environments. However, it has seen only limited application in passive sampling for measurement of freely dissolved concentrations of parent and substituted PAHs (SPAHs), which are known to be toxic, mutagenic and carcinogenic. Here, the 16 priority PAHs and some typical PAHs were selected as target compounds and were simultaneously determined by gas chromatography–mass spectrometer (GC–MS). Some batch experiments were conducted in the laboratory to explore the adsorption kinetics of the target compounds in LDPE membranes. The results showed that both PAHs and SPAHs could reach equilibrium status within 19–38?days in sorption kinetic experiments. The coefficients of partitioning between LDPE film (50?μm thickness) and water (K_LDPE) for the 16 priority PAHs were in good agreement with previously reported values, and the values of K_LDPE for the 9 SPAHs are reported in this study for the first time. Significant linear relationships were observed, i.e., log K_LDPE?=?0.705?×?log K_OW?+?1.534 for PAHs (R²?=?0.8361, p?<?0.001) and log K_LDPE?=?0.458?×?log K_OW?+?3.092 for SPAHs (R²?=?0.5609, p?=?0.0077). The selected LDPE film was also proven to meet the condition of “zero sink” for the selected target compounds. These results could provide basic support for the configuration and in situ application of passive samplers.     

两种悬浮填料在ASBBR厌氧氨氧化系统中的性能比较与微生物解析

选取聚乙烯（T1）和聚氨酯（T2）两种悬浮填料投入到两套相同厌氧序批式生物膜反应器（ASBBR）R1和R2中,以城市生活污水为配水基质,考察了两种填料在ASBBR中的性能及菌群结构特征,选出更适宜厌氧氨氧化（ANAMMOX）菌生长的填料.结果表明：R1和R2反应器分别在第93 d和73 d成功启动厌氧氨氧化,并实现稳定运行.稳定运行阶段,R1、R2系统总无机氮（TIN）平均去除率分别达88.34%、87.97%.此外,运行第150 d时,测得单个T1、T2填料的ANAMMOX菌活性分别为5.70和3.70 mg·g^-1·h^-1.同时,扫描电子显微镜（SEM）表征结果证明,球状菌在T1填料上的数量比同倍数下T2填料上多,且杂菌较少.高通量测序结果显示,T1、T2填料上Candidatus anammoxoglobus菌属相对丰度分别为75.29%和38.23%.本研究表明,相比于聚氨酯（T2）填料,聚乙烯（T1）填料更适宜ANAMMOX菌的富集.     

低密度聚乙烯(LDPE)膜对内分泌干扰物的动态富集研究

低密度聚乙烯膜(Low-Density Polyethylene,LDPE)在有机物原位被动采样中具有使用简便、耗用量少、成本低廉的优点,但在内分泌干扰物(Endocrine Disrupting Chemicals,EDCs)被动采集方面鲜见应用,有关其平衡分配系数(KLDPE)也不十分清楚.基于此,本文选取7种EDCs,包括双酚A(BPA)、壬基酚(4-NP)、辛基酚(4-t-OP)、雌酮(E1)、β17-雌二醇(E2)、三氯生(TCS)和三氯卡班(TCC),室内模拟LDPE原位动态富集过程,探究了环境因素(温度、pH)对LDPE富集效果的影响,并确定了不同EDCs在LDPE上的富集参数(KLDPE).研究发现,溶液温度升高可以加速LDPE膜对EDCs的吸附,在过低温度条件下(实验设置为4℃),EDCs较难达到膜-水分配平衡;溶液pH对于不同EDCs的影响不尽相同,这可能是因为不同pH条件下EDCs在溶液中形态差异明显,进而影响其在LDPE膜-水之间的分配平衡;7种EDCs的KLDPE实测值均低于各自的经验理论值,这主要由于经验理论值计算过程中未考虑达到分配平衡时有机物从LDPE膜上的解吸附过程,且只考虑了EDCs在膜-水两相之间的平衡.上述结果表明,为提高被动采样测定环境样品中EDCs的准确性,在尽量与实际条件相似的室内条件下获取KLDPE实测值是非常必要的.     

Degradation studies of novel degradable starch-polyethylene plastics containing oxidized polyethylene and prooxidant

Linear low-density polyethylene films were prepared that contained native corn starch (7, 14, or 28%), low or high molecular weight oxidized polyethylene (15%), and a prooxidant mixture (18% POLYCLEAN II) that contains manganese and vegetable oil. For each mixture all components were first mixed at high temperatures in a twin-screw extruder and pelletized. The pellets were cast into films using a single-screw extruder. Oxidized-polyethylene addition did not impair the transparency and thickness of the films and did not reduce the percentage elongation, whereas significant reductions in film mechanical properties were observed. Thermal and photodegradation properties of each film were evaluated by 70°C forced-air oven treatment (20 days), by high-temperature, high-humidity treatment in a steam chamber (20 days), and by exposure to ultraviolet light (365 nm; 4 weeks). Changes in the mechanical properties of the films were determined by an Instron Universal Test Machine; in the carbonyl index, Fourier transform infrared spectroscopy; and in molecular weight, by high-temperature gel-permeation chromatography (HT-GPC). The addition of oxidized polyethylene, especially high molecular weight oxidized polyethylene, and up to 14% starch to the films significantly increased the rate of thermal and photodegradation.Journal Paper No. J-15363 of the Iowa Agriculture and Home Economics Experiment Station, Ames. Project No. 0178 and 2889.     

催化燃烧法处理聚对苯二甲酸乙二醇酯生产废气

采用催化燃烧法处理聚对苯二甲酸乙二醇酯生产过程排放的含乙醛、2-甲基-1，3-二氧戊烷、乙二醇的废气，用进口Pt Pd／Al2O3-CeO2球状催化剂作废气催化燃烧的催化剂。在催化燃烧反应器床层空速为20000h^-1、催化剂用量为935mL、反应器入口温度为250℃、进口废气总烃质量浓度为2555～5099mg／m^3的条件下，处理后废气的总烃质量浓度为1～38mg／m^3，远低于120mg/m^3的国家排放标准，且总烃去除率达到98．6％～100％，乙醛质量浓度小于99mg／m^3,低于125mg／m^3的国家排放标准。     

微胶囊化红磷增效氢氧化镁阻燃聚乙烯的燃烧特性

探讨了微胶囊化红磷（MRP）在氢氧化镁（MH）阻燃低密度聚乙烯（LDPE）中的阻燃增效作用,用氧指数和锥型量热计研究了MRP/MH的不同配比对其氧指数、热释放速率、发烟量等燃烧性能参数的影响。试验结果表明在LDPE/MH体系中添加适量的MRP可以有效地提高材料的氧指数,进一步降低材料的热释放速率,延长材料的着火时间,但是材料的发烟量有所增加。从热失重实验结果可以看出,在LDPE/MH体系中添加MRP不仅大大提高材料的初始分解温度,而且具有较好的成炭作用。     

鄂尔多斯气田泥浆池防渗层对有害物质的阻滞作用评价

随着天然气勘探开发速度的加快,鄂尔多斯气田井场废泥浆产生量越来越大,固化处理后将其填埋于有防渗层的泥浆池中是目前该区域最常用的方法,但国内外就气田井场泥浆池防渗层对池内污染物实际阻滞效果的研究报道较少。为研究上述处理方法的实际环境效应,以2010年盆地内正在开发气井井场泥浆池内预固化处理沉淀物的分析结果为参照,选择其中污染程度较为严重的石油类、COD、硫化物和砷、钡、镍、铅、铜4种为重点污染物,选择2005—2009年分别投入使用的5个气田井场废弃泥浆池为考察对象,分析研究了防渗层投运时间对不同污染物阻滞作用的影响。结果表明,投运1年的防渗层可阻留污染物90%以上,投运2年以上的防渗层对污染物的阻滞作用有不同程度下降,投运5年的防渗层对所监测污染物的阻滞作用最好的是钡(40.14%)、最差的为硫化物(10.89%),结合不同时间防渗层破损状况和其对污染物的阻滞效率的变化情况,说明机械刺穿和不均匀降是导致防渗层在研究区域的环境下阻滞功能退化较快的主要原因。     

膜生物反应器中膜组件性能的对比研究

膜生物反应器中不同膜组件对废水的处理效果不同。论文主要对膜生物反应器中分别产自日本和德国的聚乙烯中空纤维膜膜组件处理生活污水的情况进行了考察,在给定的水力停留时间、污泥浓度、pH值等参数的条件下,对其膜组件性能进行了对比研究。通过对生活污水的降解试验发现,在相同的条件下,两种膜组件在浊度的去除方面均达到100%,并且系统处理出水COD均<50mg/L,去除率可分别达到86%和85%,但对氨氮去除两者均未达到60%,另外两种膜组件的膜通量的衰减相差较大,日本膜组件的衰减较缓慢而德国膜组件的衰减很快。     

废PE塑料溶剂法制氧化聚乙烯蜡

研究了在不同溶剂中以聚乙烯废塑料制高附加值氧化聚乙烯蜡产品的方法,测定了所得产物的分子量、酸值、软化点,并用IR考察了含氧基团。结果表明,溶剂A体系中能制备出颜色、分子量、酸值合格的低分子量氧化聚乙烯蜡,产品软化点在101～110℃,相对分子质量为1500,3000,酸值是12。以废塑料包装为原料,氧气做氧化剂下制得的氧化聚乙烯蜡的酸值最高。     

HDPE土工膜长期性能稳定性的研究进展

垃圾填埋场底部高密度聚乙烯(HDPE)土工膜会因氧化降解而使防渗性能降低,对环境带来二次污染风险,因此,HDPE膜的长期稳定性是值得关注的问题,但国内相关研究甚少。HDPE膜的降解过程可分为3个阶段,主要受自身性质、温度、接触介质和衬垫结构等因素的影响。文章重点综述了国外研究HDPE膜长期稳定性的试验方法,归纳了相关的数学模型,并根据存在的问题提出了建议。室内试验一般采用老化试验,包括浸泡试验和模拟试验,二者均能加快HDPE膜的老化进程。前者一般将试样完全浸泡于研究介质中试验,试验值较为保守;后者将样品置于模拟的衬垫构造中试验,结果更接近实际。数学模型采用Arrhenius模型,精度和所需参数取决于老化试验,现阶段大部分计算结果较片面,完善试验是后续工作的重点。