Ting Su,Xiaoning Wang,Xinan Chen,Yan Cheng,Zhenkai Wang,Zhangxiong Wu,Winston Duo Wu,Sheng-Peng Sun
The ferric-nitrilotriacetate (Fe3+-NTA)-catalyzed homogenous Fenton-like reaction (i.e., Fe3+-NTA/H2O2) has received increasing interest for environmental applications, but its potential in degrading trichloroethylene (TCE) in groundwater still is not well known. The results of this study showed that Fe3+-NTA/H2O2 was more effective than other Fe3+-chelate/H2O2 processes (e.g., including ethylenediaminetetraacetate, ethylenediamine-N,N′-disuccinate, citrate, malonate, and tartrate) in degrading TCE in groundwater at natural pH (∼8.0). The effects of important parameters including the ratio of NTA∶Fe3+, and the dosages of Fe3+-NTA and H2O2 were investigated. Greater than 98% degradation efficiency of TCE in actual groundwater was obtained after 60 min of reaction time under the given conditions of NTA∶Fe3+=1.5∶1, 0.1 mM Fe3+-NTA, 5 mM H2O2, and pH 8.0. Hydroxyl radical (HO•) was responsible for the degradation of TCE, and the by-products were identified as formic acid and chloride ion (Cl−). Greater than 90% degradation efficiency of TCE in a sand column was achieved under dynamic conditions [0.5 mM Fe3+-NTA (1∶1.5), 4 mM H2O2, and hydraulic retention time of 4 h], resulting in stoichiometric ratios of ΔCl−∶ΔTCE and ΔTCE∶ΔH2O2 of ∼3∶1 and 4%, respectively. Compared with iron mineral (e.g., magnetite)-catalyzed Fenton-like processes, Fe3+-NTA/H2O2 led to much smaller consumption of H2O2 (at least 1 order of magnitude smaller). In addition, the buffering capacity of bicarbonate anions (HCO3−) in groundwater had a positive effect on the degradation of TCE by Fe3+-NTA/H2O2.
Manman Liu,Luyao Wang,Chen Cheng,Zhaohui Qiu,Sheng Liu,Liu Yang,Guangyi Liu
To achieve an eco-friendly flotation separation of galena from pyrite under the low alkaline and depressant-free conditions, the triazine-dithione surfactants, such as 2-dimethylamino- s -triazine-4-thiol-6(1H)-thione sodium (DMN), 2-diethylamino- s -triazine-4-thiol-6(1H)-thione sodium (DEN) and 2-dibutylamino- s -triazine-4-thiol-6(1H)-thione sodium (DBN) were designed as the special collectors for galena. The micro-flotation results showed that the collecting capacity of these three collectors towards galena was in the order of DBN > DEN ≫ DMN, being consistent with their hydrophobization ability. In-situ AFM observed the aggregation of DBN on the whole surface of galena, which significantly enhanced the contact angle of galena. UV spectra and zeta potential recommended that the affinity of DBN towards lead ions and galena was much stronger than ferrous/ferric ions and pyrite. DFT (density functional theory) calculation revealed DBN’s two exo -S atoms were of its electron-donating center. And XPS confirmed the bonding interaction of the two exo -S atoms with Pb(Ⅱ) atoms on/in galena surface. DBN owned the mild electron-donating capacity and strong electron-accepting ability, and realized the eco-friendly flotation separation of galena from pyrite at pH ∼8.0.
The residual bacteria in the second revision surgery caused by infection would further lead to the failure of the implantation. Pathogenic bacteria adhesion to an implant surface not only interfere the functions of bone-formation related cells, but also activate the host immune system, thus resulting in inflammation and osteogenesis inhibition. Thus, to fabricate multifunctional (antibacterial, anti-inflammation and pro-osteogenesis) titanium implants is essential to address this issue. In this work, hybrid magnesium/zinc-metal organic framework (Mg/Zn-MOF74) coating was constructed on alkali-heat treated titanium (AT) surface. The hybrid Mg/Zn-MOF74 coating displayed good stability and its stability was related to the content of Zn 2+ . The MOF74-modified samples were sensitive to bacterial acid microenvironment and displayed strong antibacterial ability against both Escherichia coli and Staphylococcus aureus due to the degradation of MOF74 coating, leading to alkaline microenvironment (about pH 8.0) and degradation products (2,5-dihydroxyterephthalic acid and Zn 2+ ). The coating also showed good early anti-inflammatory property to native Ti substrates. In vivo results further verified that AT-Mg/Zn3 implants had high antibacterial and anti-inflammatory properties at early stage of implantation, and greatly improved new bone formation around implants both at non-infected and infected femur sites.
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