膨胀石墨在废水处理中的应用研究进展

综述了膨胀石墨(EG)作为一种新型功能碳材料在油类、染料、农药等废水处理中的应用研究现状。指出EG在废水处理中主要发挥吸附剂及光催化剂载体的作用。对将EG作为纳米铁及其二元金属复合材料的载体制得负载型纳米铁系金属复合材料,并将其用于废水处理的前景进行了展望。     

基于成本-效益准则的高层RC框架结构优化设计(Ⅰ)——方法

成本-效益准则是基于性能的抗震设计的重要原则,该准则在设计中除了考虑技术要素外,还考虑经济、社会等诸多因素,它所追求的设计目标为结构在其寿命周期内的总造价最小.因此,结构全寿命造价评估是基于性能的抗震设计的基本问题.在已有全寿命造价优化模型的基础上,提出了三目标函数全寿命造价优化模型.与已有的全寿命造价模型相比,该模型除考虑结构初始造价、损失期望外,还考虑了反映结构设计与施工复杂性的构件截面类型数量;另外,还将结构在其运行期间的检查、维护费用及由于优化导致建筑使用面积变化所引起的租金收益影响也列入到结构全寿命造价中.最后,基于所提出的优化模型,给出了以多目标遗传算法为搜索引擎、运用MATLAB语言开发的高层RC框架结构基于成本-效益准则的自动优化程序流程图.     

Potential risk assessment of heavy metals by consuming shellfish collected from Xiamen, China

Concentrations of Hg, Pb, Cd, and Cr in 240 shellfish including oyster, short-necked clam, razor clam, and mud clam collected from six administrative regions in Xiamen of China were measured. The daily intakes of heavy metals through the consumption of shellfish were estimated based on both of the metal concentrations in shellfish and the consuming amounts of shellfish. In addition, the target hazard quotients (THQ) were used to evaluate the potential risk of heavy metals in shellfish on human body. Results showed that the concentrations of heavy metals in shellfish ranged at the following sequence: Cr > Cd > Pb > Hg. The concentrations of Hg and Pb in most samples were below the limits (0.3 mg?kg^?1 for Hg and 0.5 mg?kg^?1 for Pb) of national standard (GB 18406.4-2001) set in China. About 57 % of samples were found to contain more than 0.1 mg?kg^?1 of Cd, in which the highest level was found in oyster from Xiangan with a value of 1.21 mg?kg^?1. The average concentrations of Cd in oyster and mud clam samples were 0.338 and 0.369 mg?kg^?1, respectively, which were significantly higher (p?<?0.05) than those in the samples of short-necked clam and razor clam. The highest concentration of Cr was found to present in short-necked clam from Jimei with a value of 10.4 mg?kg^?1, but a mean value of 1.95 mg?kg^?1 in all the shellfish was observed, and no significant difference was found among the different sampling regions. The calculated daily intakes of Hg, Pb, Cd, and Cr through consuming the shellfish were 0.005, 0.122, 0.137, and 1.20 μg?kg^?1 day^?1, respectively, which accounted for 2.19, 3.42, 13.7, and 40.1 % of the corresponding tolerable limits suggested by the Joint FAO/WHO Expert Committee on Food Additives. The THQ values of the four metals were far below 1 for most samples, except for those of Cd and Cr in the four shellfish species with the mean values of 0.132 and 0.385, respectively. The highest THQ values of Cd were observed in the species of oyster (0.719) and mud clam (0.568). But the high THQ values of Cr observed in all the four species were derived from the applied reference dose (RfD) data of Cr(VI) due to the unavailable RfD value of total Cr. The results indicate that the intakes of heavy metals by consuming shellfish collected from Xiamen of China do not present an appreciable hazard risk on human health, but attention should be paid to consuming those with relatively high THQ values, such as oyster, mud clam, and short-necked clam.     

剩余污泥超声预处理后水解酸化特性

为探讨剩余污泥超声预处理后的水解酸化特性,考察了0.6 W/mL、5 min和1 W/mL、5 min 2种超声预处理条件下污泥水解酸化过程有机质、氮、磷的释放情况。实验结果表明,2种超声预处理均可促进污泥水解酸化,并且0.6 W/mL比1 W/mL的超声预处理更有利于SCOD的释放、VFAs的产生以及氮和磷的释放;水解酸化初期,超声预处理比未经超声预处理的污泥在有机质、氮、磷释放率上差异非常明显,随着水解酸化的进行,有机质和氮释放率差异仍很明显,而磷释放程度逐渐接近;经0.6 W/mL超声预处理,污泥水解酸化3 d后,SCOD释放率、VFAs浓度、TN释放率和NH4+-N释放率分别是未经处理污泥的1.85、2.63、1.85和1.41倍,而TP和PO43--P释放率较未经处理污泥仅分别多2.44和1.23个百分点。研究表明,控制适宜的声能密度、超声时间和水解酸化进程是超声预处理强化剩余污泥水解酸化效果的关键。     

垃圾焚烧炉干燥段通风阻力特性实验研究

倾斜往复式炉排是我国城市生活垃圾焚烧炉中经常采用的炉排形式之一。垃圾在炉排干燥段的干燥效果直接影响到其着火和燃烧,因此炉排下侧送出的一次风在垃圾层中的流通性显得尤其重要。本研究通过搭建冷态试验台,以Steinmuller炉排为例,测量了炉排和不同厚度的垃圾层在不同一次风流量下的阻力,并研究了炉排和垃圾层的通风阻力特性,为今后更好地组织和控制高水份垃圾在炉内的干燥预热和着火燃烧提供了设计依据。     

TiO_2/NiPECO体系降解DMP的动力学和光电协同作用研究

以采用微波辅助法制备的TiO2/Ni光电极为阳极,纤维状石墨毡材料(graphite felt,GF)为阴极,饱和甘汞电极(saturated calomel electrode,SCE)为参比电极建立TiO2/Ni光电催化氧化(PECO)体系.以邻苯二甲酸二甲酯(dimethyphthalate,DMP)为目标物,研究其光电催化降解反应动力学和光电协同作用.结果显示:DMP的降解符合拟一级动力学规律;当DMP初始浓度一定时,影响DMP光电催化降解速率的因素由强到弱依次为:催化剂有效面积,紫外光强度,曝氧速率,外加偏转电压等.实验证明本体系中光电之间具有协同作用.     

CdS-TiO_2/MWCNTs结构表征及其光催化性能

采用溶胶-凝胶法,制备了多壁碳纳米管(MWCNTs)负载的双组分复合半导体光催化剂CdS-TiO2/MWCNTs。通过透射电镜(TEM)、比表面分析(BET)、X射线衍射(XRD)和紫外-可见吸收光谱(UV-vis)等分析方法对光催化剂进行了结构表征,并考察了CdS-TiO2/MWCNTs对甲苯降解的光催化性能。结果表明:纳米活性粒子CdS-TiO2均匀负载于MWCNTs上,比表面积、光吸收阈值和强度增大,活性粒子间以及活性粒子与载体之间具有协同作用,有利于光催化性能的提高,CdS-TiO2/MWCNTs在主波长为254 nm紫外光照射下对甲苯的降解效果较好,去除率可达55.3%。     

东莞市污水处理厂升级改造工艺路线初探

针对东莞市38个污水处理厂的实际情况,通过对目前城市污水处理厂常用的二级处理工艺进行技术升级改造时可能采用的深度处理工艺技术的综合分析比较,推荐了NPR、CNR、人工湿地三种工艺作为尾水的深度处理备选技术,提出了东莞市污水处理厂升级改造应优先采用CNR工艺,并可为我国不同地区、不同发展时期满足不同的水质需求进行污水处理厂工艺升级改造提供技术支持。     

印刷线路板在复合环境下的腐蚀

印刷线路板几乎会出现在每一种电子设备当中,它是以绝缘材料辅以导体配线所形成的结构元件。印刷线路板的腐蚀形式符合大气腐蚀的基本规律,但又有自己的特点。本文概述了印刷线路板在气体污染物、灰尘、潮湿、高温等多因素复合环境条件下的失效形式及腐蚀机理,其主要的腐蚀形式是:电偶腐蚀、电解腐蚀和缝隙腐蚀;文中还简单总结了印刷线路板腐蚀的主要影响因素,其主要的影响因素是:湿度、温度、腐蚀性气体和固态污染物等。     

Carbonaceous matter and PBDEs on indoor/outdoor glass window surfaces in Guangzhou and Hong Kong,South China

Organic films, collected from indoor and outdoor window surfaces in Guangzhou and Hong Kong of South China, were analyzed to quantify their organic carbon (OC), elemental carbon (EC), and polybrominated diphenyl ethers (PBDEs) content. The highest concentrations of OC, EC, and BDE-209 were found in Guangzhou with values of 10 000 μg m^?2, 2200 μg m^?2, and 4000 ng m^?2, respectively, and the highest concentration of Σ₇PBDE (sum of BDE-28, -47, -99, -100, -153, -154 and -183) was found in Hong Kong with a value of 25 ng m^?2. In most cases, the concentrations of PBDEs were higher in the exterior films than those in the interior films with BDE-209 as the predominant congener in both cities, suggesting that PBDEs mainly come from ambient environment, and deca-BDE accounts for major PBDE consumption. The growth rates of organic film on window surfaces were fast at the beginning, and reached a consistent level afterwards. The evolution rates ranged from 2.6 to 11 nm day^?1 for “bulk film”, while from 0.06 to 0.92 nm day^?1 for “pure film”. The concentrations of PBDEs on the window surfaces did not increase with the growth time, suggesting that the window surface may provide a good place for photo-degradation of PBDEs.