Active Moss Biomonitoring Applied to an Industrial Site in Romania: Relative Accumulation of 36 Elements in Moss-Bags

Active moss biomonitoring using the species Sphagnum girgensohnii was tested at a strongly polluted site in Romania (Baia Mare) according to a novel sampling design. Nine moss transplants from each of the two background areas (Dubna, Russia and Vitosha Mountain, Bulgaria) were deployed in parallel on balconies about 24 m above street level for 4 months. The samples were analyzed for 36 elements using instrumental neutron activation analysis (INAA). Based on the results obtained the sampling variability is discussed in relation to the analytical variability, and the relative uptake of the different elements is assessed. The moss-bags using Sphagnum girgensohnii demonstrate a high or a very high relative uptake for a majority of the 36 investigated elements, but the values depend on the initial element concentration in the moss. Moss leaves analyzed separately showed somewhat higher levels than stems for many elements. Practical considerations however still speak in favor of using the whole moss for transplants.     

电活化过硫酸盐降解全氟辛酸及其中间产物的探究分析

全氟化合物（PFCs）是一种新兴的持久性有机污染物,具有环境持久性、高毒性和难降解性,因此急需研发高效的降解方法.本文采用电化学恒电位电解法活化过硫酸盐,利用得到的具有强氧化性的SO₄^·-有效降解全氟辛酸（PFOA）,考察了恒定电位值、过硫酸钠的初始浓度、溶液初始pH值和共存离子对电活化过硫酸盐降解PFOA的影响.同时,结合超高效液相色谱-三重串联四级杆质谱联用仪（UPLC-MS/MS）和气相色谱与质谱联用仪（GC-MS）,对其降解的液相和气相中间产物进行探究.结果表明,在控制阴极电位为-1.8 V,初始过硫酸钠溶液浓度为200 mmol·L^-1,初始溶液pH=3.29,恒电位电解4 h后,PFOA去除率约达到60%.当体系中有NO₃^-、异丙醇和过硫酸钠共存时,PFOA降解效率明显提高（91%,4 h）,当有ClO₄^-存在时PFOA去除率约达到76.8%,但HCO₃^-和Cl^-的存在会出现抑制效果.通过对降解中间产物（短链PFCAs和加氢产物）和TOC去除率（62.5%,24 h）的监测分析,进而推断其可能的降解机理为SO₄^·-介导的Kolbe脱羧过程和羧酸逐步被加氢还原的过程.     

有机氯对废弃物衍生焦炭结构和反应活性的影响

采用聚氯乙烯（PVC）为氯源与废弃物典型组分等量混合后在500 ℃氮气气氛条件下制成焦炭样品,通过热重（TGA/DTG）、扫描电子显微镜（SEM）、能谱（EDS）和拉曼光谱分析手段,对样品进行了焦炭碳结构和反应活性分析.结果表明,有机氯会抑制废弃物衍生焦炭的活性,使淀粉热解焦炭最大反应速率从0.15 min^-1下降至0.13 min^-1.动力学方面,淀粉（60.575 kJ·mol^-1）和纤维素焦炭（101.686 kJ·mol^-1）样品的表观活化能均小于其与PVC混合物的热解焦炭;而PVC的添加则会使淀粉和纤维素热解焦炭中的C结构更趋于无序化.微观角度方面,添加PVC后的焦炭表面同样呈现出纤维丝状结构,但气壁更加粗糙,表面有较多的褶皱,破坏了由废弃物内在碱金属催化形成的孔隙结构,使得焦炭表面结构破碎化程度更高.     

Mesoporous cobalt monoxide-supported platinum nanoparticles: Superior catalysts for the oxidative removal of benzene

Mesoporous Co_3 O_4(meso-Co_3 O_4)-supported Pt(0.53 wt.% Pt/meso-Co304) was synthesized via the KIT-6-templating and polyvinyl alcohol(PVA)-assisted reduction routes.Mesoporous CoO(meso-CoO) was fabricated through in situ reduction of meso-Co304 with glycerol,and the 0.18-0.69 wt.% Pt/meso-CoO samples were generated by the PVA-assisted reduction method.Meso-Co_3 O_4 and meso-CoO were of cubic crystal structure and the Pt nanoparticles(NPs) with a uniform size of ca.2 nm were well distributed on the mesoCo_3 O_4 or meso-CoO surface.The 0.56 wt% Pt/meso-CoO(0.56 Pt/meso-CoO) sample performed the best in benzene combustion(T_(50%)=156℃and T_(90%)=186℃at a space velocity of 80,000 mL/(g h)).Introducing water vapor or C02 with a certain concentration led to partial deactivation of 0.56 Pt/meso-CoO and such a deactivation was reversible.We think that the superior catalytic activity of 0.56 Pt/meso-CoO was intimately related to its good oxygen activation and benzene adsorption ability.     

高温老化气氛对单钯三元催化剂活性的影响

本文制备了一种含Y、Ce和Zr的单钯三元催化剂(Pd-YCZ).在1050℃下,分别于空气和配气中对这一催化剂进行了高温老化,并对其催化活性进行了测试.实验结果表明,Pd-YCZ在空气中老化后的活性优于其在配气中老化后的活性.     

Peroxymonosulfate activation by Fe-N-S co-doped tremella-like carbocatalyst for degradation of bisphenol A: Synergistic effect of pyridine N, Fe-Nx, thiophene S

Bisphenol A (BPA) has received increasing attention due to its long-term industrial application and persistence in environmental pollution. Iron-based carbon catalyst activation of peroxymonosulfate (PMS) shows a good prospect for effective elimination of recalcitrant contaminants in water. Herein, considering the problem about the leaching of iron ions and the optimization of heteroatoms doping, the iron, nitrogen and sulfur co-doped tremella-like carbon catalyst (Fe-NS@C) was rationally designed using very little iron, S-C₃N₄ and low-cost chitosan (CS) via the impregnation-calcination method. The as-prepared Fe-NS@C exhibited excellent performance for complete removal of BPA (20 mg/L) by activating PMS with the high kinetic constant (1.492 min⁻¹) in 15 min. Besides, the Fe-NS@C/PMS system not only possessed wide pH adaptation and high resistance to environmental interference, but also maintained an excellent degradation efficiency on different pollutants. Impressively, increased S-C₃N₄ doping amount modulated the contents of different N species in Fe-NS@C, and the catalytic activity of Fe-NS@C-1-x was visibly enhanced with increasing S-C₃N₄ contents, verifying pyridine N and Fe-N_x as main active sites in the system. Meanwhile, thiophene sulfur (C-S-C) as active sites played an auxiliary role. Furthermore, quenching experiment, EPR analysis and electrochemical test proved that surface-bound radicals (^·OH and SO₄^⋅−) and non-radical pathways worked in the BPA degradation (the former played a dominant role). Finally, possible BPA degradation route were proposed. This work provided a promising way to synthesize the novel Fe, N and S co-doping carbon catalyst for degrading organic pollutants with low metal leaching and high catalytic ability.     

非均相活化剂磁性纳米CoFe2O4的制备及其活性评价

采用溶胶-凝胶法制备了磁性纳米铁酸钴（CoFe₂O₄）固体颗粒，并采用扫描电镜（SEM），X射线衍射仪（XRD），傅里叶变换红外光谱仪（FT-IR）和振动样品磁强计对样品进行表征分析.以磁性纳米CoFe₂O₄颗粒活化过硫酸盐氧化去除水中四环素为探针反应，评价CoFe₂O₄颗粒的活化性能.结果表明，600℃焙烧温度下制备出的固体颗粒，其活性较高，颗粒表面金属离子浸出率较低；优化温度下制备的CoFe₂O₄颗粒在较宽的pH值范围（4.4~9.0）内均具有较高活性；控制实验条件PDS₀ 1g/L，CoFe₂O₄ 1g/L，TCH₀ 50mg/L，20℃，pH₀ 4.4，反应4h后TCH去除率达到82.0%.CoFe₂O₄颗粒循环重复利用10次后仍保持较高的活性和结构稳定性，而且因其特殊的磁性能便于回收利用.     

典型硼化合物与磷酸二氢铵协效阻燃松木的燃烧性能及热解动力学研究

利用木垛法和热重分析法比较研究了硼酸、硼砂与磷酸二氢铵复配阻燃松木的燃烧性能、热解特性及热解反应动力学。结果表明,单种阻燃剂使用时,磷酸二氢铵的阻燃效果优于硼酸和硼砂;两两复配使用具有明显的协效作用,其中阻燃效果:磷酸二氢铵/硼酸＞磷酸二氢铵/硼砂＞硼酸/硼砂,而硼酸与磷酸二氢铵在质量比为2:3时,协效阻燃效果最好。与未处理松木相比,阻燃剂的加入降低了松木在热解阶段的初始分解温度和峰值分解温度,缩短了热解区间,并降低了松木在主要热解阶段的表观活化能,其中热解阶段活化能越低的阻燃松木在燃烧过程中成炭效果和阻燃性能越好。     

Kinetic analysis for spontaneous combustion of sulfurized rust in oil tanks

In order to evaluate the spontaneous combustion hazards of sulfurized rust in oil tanks, one kind of rust was obtained from respiratory valve inner cavity of a crude oil tank in a petrochemical company. The rust was sulfurized in sulfuration experimental apparatus. The production was analyzed by X-ray energy dispersive spectrometry (EDS), scanning electron microscopy (SEM) and then thermo-gravimetric analysis (TGA). The EDS result shows that the main substances are FeS and FeS₂ which are liable to spontaneous combustion. The sulfurized rust gives a short length of side and diamond appearance, and a large pore size in structure based on X-ray Diffraction (XRD). The whole oxidation process has three complex stages. The corresponding apparent activation energy values, most probable mechanism functions and pre-exponential factor values were calculated by Madhusudanan–Krishnan–Ninan method and the master plot method. The results indicate that the first and third stages of mass loss are up to the power function mechanism, but the second stage accords with the nucleation and nucleus growth mechanism. The values of apparent activation energy increase successively from the first stage to the third stage. The second stage has the maximum pre-exponential factor value, while the first has the minimum. With the obtained parameters above, the oxidation process of sulfurised rust could be simulated, which would benefit for monitoring and early warning of oil tanks.     

Steam activation,characterisation and adsorption studies of activated carbon from maize tassels

In this paper, steam-produced activated carbon (STAC) from maize tassel (MT) was evaluated for its ability to remove basic dye (methylene blue MB) from aqueous solution in a batch adsorption process. The equilibrium experiments were conducted in the range of 50–300 mg/L initial MB concentrations at 30°C, for effect of pH, adsorbent dosage and contact time. The experimental data were analysed by Langmuir, Freundlich and Temkin isotherm models of adsorption. Freundlich adsorption isotherm was found to have highest value of R²(R²=0.97) compared to other models of Langmuir and Temkin having (0.96 and 0.95 respectively). STAC has a high adsorptive capacity for MB dye (200 mg/g) and also showed favourable adsorption for the dye with the separation factor (R_L<1) for the dye-activated carbon system. The kinetic data obtained were analysed using pseudo first-order kinetic equation and pseudo second-order kinetic equation. The experimental data fitted well into pseudo second-order kinetic equation, as demonstrated by the high value of R².