苯乙烯的三维荧光特性及水污染应急处理

苯乙烯对人体健康和自然环境具有极大的危害,是国际卫生组织确认的致癌物。历年来,苯乙烯泄漏事故频繁发生,对饮用水安全造成了极大的隐患。对水中苯乙烯污染进行快速监测并采取切实有效的应急处理措施有助于保障饮用水的卫生安全。利用三维荧光光谱技术对苯乙烯的水溶液进行分析,发现在Ex255/Em305处有一个明显的荧光峰,荧光峰值与苯乙烯溶液浓度呈现良好的线性相关,相关系数r达到了0.995 7,其颜色随浓度增加而变深。苯乙烯中共有4个共轭π键,其中苯环具有大的共轭π键结构,乙烯基上同样具有一个共轭π键。同时,苯乙烯的分子结构中,碳原子处于同一个平面上,属于平面构型且具有一定的刚性,符合强荧光物质所具有的特征。因此通过三维荧光扫描结合苯乙烯的荧光特性,能快速测定水体中苯乙烯浓度及判断水体的污染程度。粉末活性炭可以有效地吸附去除水中的苯乙烯。当苯乙烯在源水中的浓度达到《生活饮用水卫生标准》规定的限值0.02 mg·L-1时,采用180目的粉末活性炭,投加量为15 mg·L-1时,苯乙烯浓度可降至0.001 mg·L-1,去除率达95.5%。     

增效反应中聚合氯化铝红外结构特征的变化

对聚合氯化铝 (PAC)进行增效改性是制备高性能无机高分子絮凝剂的重要手段之一。用多核络合剂络合、聚合硅酸交联和聚丙烯酰胺复合三种增效方法改性PAC ,分别获得了结构有别于PAC的新型絮凝剂CO PAC ,CR PAC和PAM PAC。其傅里叶红外光谱 (FTIR)表明 ,在三种无机高分子结构中均存在Al—OH以外的新化学键 ,且原有基团的特征吸收峰位置因受结构畸变而发生一定的低频红移 ,证实了PAC增效反应并不是单纯的物理混合加成作用 ,而是形成了具有特殊结构的无机高分子的化学反应。这类无机高分子絮凝剂所具有的优良絮凝特性是由增效剂和PAC间以化学作用为主的物理化学因素共同作用的结果。     

Electric-field gradients at Ta donor impurities in Cr2O3(Ta) semiconductor

We report perturbed-angular-correlation (PAC) experiments on ¹⁸¹Hf(→¹⁸¹Ta)-implanted corundum Cr₂O₃ powder samples in order to determine the magnitude and symmetry of the electric-field gradient (EFG) tensor at Ta donor impurity sites of this semiconductor. These results are analyzed in the framework of ab initio full-potential augmented-plane wave plus local orbitals (FP−APW+lo) calculations. The results are also compared with EFG results coming from PAC experiments in isomorphous α-Al₂O₃ and α-Fe₂O₃ doped with ¹¹¹In→¹¹¹Cd and ¹⁸¹Hf→¹⁸¹Ta tracers. This combined analysis enables us to quantify the magnitude of the lattice relaxations induced by the presence of the impurity and to determine the charge state of the impurity donor level introduced by Ta in the band gap of the semiconductor.     

PAC Investigation of Amorphous Ferromagnets

The amorphous ferromagnetic alloy Fe79/B16/Si5 was investigated by PAC. For that the probe atoms ¹¹¹In(¹¹¹Cd) and ^111mCd were implanted at the ISOLDE on-line separator. The distributions of magnetic hyperfine fields were determined. Below the crystallization temperature α-Fe clusters could be observed. For comparison Mössbauer transmission experiments were performed.     

Effect of Mg2+ on the Magnetic Compensation of Lithium–Chromium Ferrite

PAC measurements on ¹¹¹In(¹¹¹Cd) implanted and thermally treated α-Fe have shown an indication for a cubic defect with the ¹¹¹Cd probe in the centre of it. The measured room temperature (R. T.) magnetic hyperfine fields are B _hf1 = −38.4(8) T for substitution and B _hf2 = +11.5(3) T for the cubic defect. Additionally, probes with pure quadrupole frequency distributions were observed, which are incorporated in surface contaminations.     

复苏促进因子增效PACT处理印染废水

利用复苏促进因子（resuscitation-promoting factor,Rpf）促进活的但不可培养 （viable but non-culturable,VBNC）的细菌复苏和生长的特性,通过序列间歇式活性污泥法（SBR）实验,探究用Rpf增效粉末活性炭活性污泥工艺（powder activated carbon treatmeat,PACT）处理印染废水的最佳工况,同时研究了Rpf对活性污泥的强化机理和对微生物的影响。实验选用302型木质粉末活性炭（PAC）,得到最佳投加条件为PAC 30 mg·L^-1·d^-1,Rpf 6 mg·L^-1·（3 d）^-1。实验表明,PAC和Rpf具有协同作用,可改善污泥的沉降性能,增强传统PACT的生化处理能力,提高活性污泥微生物的多样性,增大种群丰度,使系统稳定高效运行。     

磁场耦合电化学合成聚合氯化铝的性能

以金属铝板为阳极,金属铁板为阴极,0.1 mol/L的AlCl3水溶液作电解液,应用与重力方向平行的外加磁场耦合直流电解法合成聚合氯化铝(PAC).在磁通密度0.4 T,相邻电极间距15 mm,电解槽电压2.4V,电流密度300 A/m2下,成功制备出盐基度Ba=2.4,总铝含量(AlT)为0.6 mol/L,有效絮凝成分Al13占AlT83.2%的PAC产品,其电压效率85.2%,电能效率81.5%,比电极面积为140.1 m2/m3.恒流法测试表明,磁场对电极极化有抑制作用,并可增大电极表面膜溶解速率,且随磁通密度增加而增强.     

Natural organic matter removal by coagulation during drinking water treatment: A review

Natural organic matter (NOM) is found in all surface, ground and soil waters. An increase in the amount of NOM has been observed over the past 10-20 years in raw water supplies in several areas, which has a significant effect on drinking water treatment. The presence of NOM causes many problems in drinking water and drinking water treatment processes, including (i) negative effect on water quality by causing colour, taste and odor problems, (ii) increased coagulant and disinfectant doses (which in turn results in increased sludge volumes and production of harmful disinfection by-products), (iii) promoted biological growth in distribution system, and (iv) increased levels of complexed heavy metals and adsorbed organic pollutants. NOM can be removed from drinking water by several treatment options, of which the most common and economically feasible processes are considered to be coagulation and flocculation followed by sedimentation/flotation and sand filtration. Most of the NOM can be removed by coagulation, although, the hydrophobic fraction and high molar mass compounds of NOM are removed more efficiently than hydrophilic fraction and the low molar mass compounds. Thus, enhanced and/or optimized coagulation, as well as new process alternatives for the better removal of NOM by coagulation process has been suggested. In the present work, an overview of the recent research dealing with coagulation and flocculation in the removal of NOM from drinking water is presented.     

The Electric Field Gradient of 111Ag in Macrocyclic Crown Thioethers

Time differential perturbed angular correlation experiments and ab-initio density functional theory calculation were used to determine the electric field gradients of the metal centres of the macrocyclic crown thioethers Ag(15S5)[BF₄], Ag(18S6-CH₂OH)[CF₃SO₃], Ag(18S6)⁺, Ag(19S6-OH)[Tosylat] and Ag(20S6-OH)[CF₃SO₃]. The density functional theory calculations have been performed with the Amsterdam Density Functional code ADF. A “fingerprint system” is introduced, which allows to assign electric field gradients to certain Ag coordinations in these crown thioether complexes.     

Site Occupation of In in RAg6In6 Studied Using PAC Spectroscopy

PAC measurements were performed for ¹¹¹In in LaAg₆In₆, PrAg₆In₆ and NdAg₆In₆. It appears that the probe atom occupy three available sites in the crystal lattice with quite a similar probability. There is a small preference for In atoms to occupy a selected lattice site which is not the same in different compounds.