Estrogens as a kind of steroidal sex hormone are widely used in humans, especially quinestrol(QS),dienestrol(DS) and norethindrone(NET, 19-nor-17-alphaethinltestoster-one), which cannot be completely degraded after application. Steroidal estrogens at low concentration pulling into environment can disturb the normal biological function of wide life and thus lead to great threat to humans. So it is important to explore its degradation mechanism and its behavior in the environment. In this study, we investigated the oxidation or reduction system under gamma irradiation for reducing estrogenic activity in the aqueous solutions as well as degradation kinetics, its by-products and yield of transformation by different analytical methods such as GC–MS and HPLC. Gamma irradiation could effectively degrade estrogens in aqueous solution. The degradation reaction of estrogens could be depicted by first-order reaction kinetics. The total organic carbon of solution decreased with an increasing absorbed dose with the order: quinestrol [ norethindrone [ dienestrol. The toxicity of the three estrogens was declined after irradiation. Mono- and quadric-hydroxylated intermediates as well as organic acids were formed after gamma irradiation.
Ming-Hong WuJia-Ling LiXiang-Xin HeGang XuGuo-Ji DingWen-Yan Shi
In recent years,numerous classes of carbon-based nanomaterials,such as carbon nanotubes(CNTs),carbon dots(CDs),graphene and its derivatives,graphene quantum dots(GQDs)and fullerene,have been deeply explored for potential applications in the biological fields,e.g.,bioimaging[1-5],biosensing[6,7],drug nanocarrier[8-12],etc.,owing to their unique and alluring physical and chemical properties.Among them,GQDs are a subject of interesting and promising research with many advantages such as strong signal strength,resistance to photobleaching,tunable fluorescence emissions,high sensitivity and biocompatibility[13-35].Compared with those semiconductor QDs,GQDs have remarkable superior让y in low toxicity,excellent biocompatibility,low cost,and abundance of original materials in nature[36].High quality GQDs have a wide range of applications,such as light emitting diodes(LEDs)[37,38],solar cells[39,40]and photocatalysis[41,42],aside from biological fields.Up to now,various GQDs with different photoluminescent(PL)colors have been synthesized by two dominating approaches including top-down and bottomup methods.The top-down method refers to cutting bulk carbon materials into nanoscale-carbon materials by necessary physical and chemical processes[43].
Nanomaterials have attracted considerable interest owing to their unique physicochemical properties.The wide application of nanomaterials has raised many concerns about their potential risks to human health and the environment.Metal oxide nanopartides（MONPs）,one of the main members of nanomaterials,have been applied in various fields,such as food,medicine,cosmetics,and sensors.This review highlights the bio-toxic effects of widely applied MONPs and their underlying mechanisms.Two main underlying toxicity mechanisms,reactive oxygen species（ROS）-and non-ROS-mediated toxidties,of MONPs have been widely accepted.ROS activates oxidative stress,which leads to lipid peroxidation and cell membrane damage.In addition,ROS can trigger the apoptotic pathway by activating caspase-9 and-3.Non-ROS-mediated toxicity mechanism includes the effect of released ions,excessive accumulation of NPs on the cell surface,and combination of NPs with specific death receptors.Furthermore,the combined toxicity evaluation of some MONPs is also discussed.Toxicity may dramatically change when nanomaterials are used in a combined system because the characteristics of NPs that play a key role in their toxicity such as size,surface properties,and chemical nature in the complex system are different from the pristine NPs.
In this study, we have investigated the degradation and primary radiolytic degradation mechanism of 4-tert-octylphenol (4-t-OP) by using of electron beam (EB) -irradiation. The results show that at an absorbed dose of 10 kGy and an initial concentration of 25 mg·L -1 , the degradation of 4-t-OP in a methanol/water reduction system is higher than in a acetonitrile/water oxidation system by 19.4% and higher than in an acetone/water system by 26.8%, which is due to both of ·OH and e aq - playing an important role in the decomposition of 4-t-OP, although the latter is more effective. The degradation rate of 4-t-OP will decrease with increment of absorbed dose in a methanol/water solution, and increase with decrement of initial concentration at a constant absorbed dose. The degradation efficiency will also decrease with the addition of anions and H 2 O 2 into the solution. A system saturated with N 2 will make an increment in the degradation of 4-t-OP. The pH value of solution has been also found to affect the degradation efficiency, while the degradation is more efficient in alkaline conditions. Finally, the initial products involved in degradation reaction have been determined to be ethylbenzene, styrene, bicyclo[4.2.0]octa-1,3,5-triene, 2,2,4-trimethylpentane and p-tert-butyl-phenol, which may arise from e aq - attack at the position of the alkyl side chain of 4-t-OP molecule. The results have been revealed that EB irradiation is a promising method for degradation of 4-t-OP, and e aq - may be main reactive species to attack at the position of the alkyl side chain of 4-t-OP.
WANG Liang WU Minghong XU Gang LIN Ning BU Tingting ZHENG Jisan TANG Liang
An analytical method is presented for the quantification of seven Polybrominated Diphenyl Ethers （PBDEs） in ur...
Minghong Wu 1 , Zuyi Chen 1 , Jing Ma 1 , Jianqiu Lei 2 1 School of Environmental and Chemical Engineering, Shanghai University, Shanghai, 200444, China 2 Shanghai Institute of Optics and Fine Mechanics, Chinese Academy of Sciences, Shanghai 201800, P. R. China
E-beam degradation of bisphenol A(BPA) was carried out,under reductive condition of ethanol-water solution and oxidative condition of acetonitrile-water solution.The degradation efficiency is higher in oxidative condition than that in reductive condition,and increases with the dose but decreased with increasing initial concentration.The BPA radiolysis follows the pseudo-first-order kinetics.Adding H_2O_2,or neutral condition,does not benefit BPA degradation in oxidative conditions.Pulsed radiolysis was used to investigate mechanism of the BPA radiolysis.The rate constant for BPA reaction with OH(1.85×10^(10) L·mor^(-1)·s^(-1)) is about an order of magnitude higher than that with e_(aq)^-(1.80×l0~9 L·mor^(-1)·s^(-1)).The degradation products were analyzed by ion chromatograph.Smaller molecules such as formic acid and acetic acid were detected,indicating that ^-OH attacks the BPA molecule.The work is of significance for the practical E-beam treatment of waste water containing BPA.
XU Gang REN Hua WU Ming-Hong LIU Ning YUAN Qing TANG Liang WANG Liang
