- Effects of different scrap iron as anode in Fe-C micro-electrolysis system for textile wastewater degradation. [Journal Article]
- ESEnviron Sci Pollut Res Int 2019 Jul 13
- The degradation of organic contaminants in actual textile wastewater was carried out by iron carbon (Fe-C) micro-electrolysis. Different Fe-C micro-electrolysis systems (SIPA and SISA) were establish…
The degradation of organic contaminants in actual textile wastewater was carried out by iron carbon (Fe-C) micro-electrolysis. Different Fe-C micro-electrolysis systems (SIPA and SISA) were established by using scrap iron particle (SIP) and scrap iron shaving (SIS) as anode materials. The optimal condition of both systems was obtained at the initial pH of 3.0, dosage of 30 g/L and Fe/C mass ratio of 1:1. Commercial spherical Fe-C micro-electrolysis material (SFC) was used for comparison under the same condition. The results indicated that total organic carbon (TOC) and chroma removal efficiencies of SIPA and SISA were superior to that of SFC. Total iron concentration in solution and XRD analysis of electrode materials revealed that the former showed relatively high iron corrosion intensity and the physicochemical properties of scrap iron indeed affected the treatment capability. The UV-vis and 3DEEM analysis suggested that the pollutants degradation was mainly attributed to the combination of reduction and oxidation. Furthermore, the potential degradation pathways of actual textile wastewater were illustrated through the GC-MS analysis. Massive dyes, aliphatic acids, and textile auxiliaries were effectively degraded, and the SIPA and SISA exhibited higher performance on the degradation of benzene ring and dechlorination than that by SFC. In addition, SIPA and SISA exhibited high stability and excellent reusability at low cost. Graphical abstract.
- Reductive dechlorination of trichloroethene under different sulfate-reducing and electron donor conditions. [Journal Article]
- JCJ Contam Hydrol 2019 Jul 04; 226:103519
- The effect of sulfate presence on reductive dechlorination of chlorinated ethenes has been a matter of conflict among the limited reports found in literature. This paper aims to clarify the misconcep…
The effect of sulfate presence on reductive dechlorination of chlorinated ethenes has been a matter of conflict among the limited reports found in literature. This paper aims to clarify the misconceptions regarding the performance of trichloroethene biotransformation under sulfate reducing conditions by evaluating the effect of different sulfate concentrations on reductive dechlorination and to assess the influence of electron donor dose on dechlorination rate. To this end, batch experiments containing different sulfate and butyrate concentrations were conducted using trichloroethene-dechlorinating and sulfate-reducing parent cultures. Results demonstrated that if sufficient time and electron donor is provided, complete dechlorination can be achieved, even at up to 400 mg/L initial sulfate concentration. However, the rate of dichloroethene and vinyl chloride degradation is reduced as sulfide concentration increases. Moreover, the excess electron donor dose induced a slightly slower dechlorination rate. The findings of this paper present an explanatory framework for the dechlorination of TCE under sulfate reducing conditions and can contribute to the state-of-art bioremediation of contaminated sites.
- Removal of 2,4-Dichlorophenoxyacetic acid from water and organic by-product minimization by catalytic ozonation. [Journal Article]
- JEJ Environ Health Sci Eng 2019; 17(1):85-95
- CONCLUSIONS: In uncatalysed ozonation degradation of 2,4-DCPA acid improved with the increase in hydroxide ion concentration. Ozonation in presence of 7:3 Fe:Ni (Co-ppt) catalyst resulted in highest activity for dechlorination, TOC removal and Org-BP minimization, thus improving the quality of contaminated water.
- Understanding the electrode reaction process of dechlorination of 2,4-dichlorophenol over Ni/Fe nanoparticles: Effect of pH and 2,4-dichlorophenol concentration. [Journal Article]
- JEJ Environ Sci (China) 2019; 84:13-20
- Herein, with the exploitation of iron and nickel electrodes, the 2,4-dichlorophenol (2,4-DCP) dechlorinating processes at the anode and cathode, respectively, were separately studied via various elec…
Herein, with the exploitation of iron and nickel electrodes, the 2,4-dichlorophenol (2,4-DCP) dechlorinating processes at the anode and cathode, respectively, were separately studied via various electrochemical techniques (e.g., Tafel polarization, linear polarization, electrochemical impedance spectroscopy). With this in mind, Ni/Fe nanoparticles were prepared by chemical solution deposition, and utilized to test the dechlorination activities of 2,4-DCP over a bimetallic system. For the iron anode, the results showed that higher 2,4-DCP concentration and solution acidity aggravated the corrosion within the electrode. The charge transfer resistance (Rct) values of the iron electrode were 703, 473, 444, and 437 Ω∙cm2 for the initial 2,4-DCP concentrations of 0, 20, 50, and 80 mg/L, respectively. When the bulk pH of the 2,4-DCP solution varied from 3.0, 5.0 to 7.0, the corresponding Rct values were 315, 376, and 444 Ω∙cm2, respectively. For the nickel cathode, the reduction current densities on the electrode at -0.75 V (vs. saturated calomel electrode) were 80, 106, and 111 μA/cm2, for initial 2,4-DCP concentrations of 40, 80, and 125 mg/L. The dechlorination experiments demonstrated that when the initial pH of the solution was 7.0, 5.0, and 3.0, the dechlorination percentage of 2,4-DCP by Ni/Fe nanoparticles was 62%, 69%, and 74%, respectively, which was in line with the electrochemical experiments. 10 wt.% Ni loading into Ni/Fe bimetal was affordable and gave a good dechlorination efficiency of 2,4-DCP, and fortunately the Ni/Fe nanoparticles remained comparatively stable in the dechlorination processes at pH 3.0.
- Assembly of root-associated microbiomes of typical rice cultivars in response to lindane pollution. [Journal Article]
- EIEnviron Int 2019 Jul 05; 131:104975
- Organochlorine pesticides have been extensively used for many years to prevent insect diseases of rice (Oryza sativa L.), but little is known about their residual impacts on the underground micro-eco…
Organochlorine pesticides have been extensively used for many years to prevent insect diseases of rice (Oryza sativa L.), but little is known about their residual impacts on the underground micro-ecology in anaerobic environment. In this glasshouse study, we characterized the lindane effects on the assembly of root-associated microbiomes of commonly used indica, japonica and hybrid rice cultivars, and their feedback in turn, in modifying lindane anaerobic dissipation during 60 days' rice production. The results showed that rice growth inhibited the anaerobic dissipation of lindane, but was not affected apparently by lindane at initial spiked concentration of 4.62 and 18.54 mg kg-1 soil. Suppressed removal of lindane in rice planted treatments as compared with that in unplanted control was likely due to inhibited reductive dechlorination induced by a comprehensive effect of radial O2 secretion of rice root and co-occurring Fe(III) reduction that consumed electron competitively in rice rhizosphere. However, the hybrid cultivar exhibited a less suppression than the conventional cultivars in high polluted soils. Bacteria was more sensitively responded to lindane pollution than fungal taxa, and Actinobacteria, Chloroflexi, Verrucomicrobia and Proteobacteria were the main different phyla between hybrid and conventional cultivars, with a more stable community structure exhibited in the hybrid rice under lindane stress. Our study highlights the assembly and variation of root-associated microbiomes in responses of lindane pollution, and suggests that hybrid rice cultivar might be most competent for cultivation in paddy fields polluted by lindane and other organochlorine pesticides, especially in the area with high residual levels.
- Accelerated microbial reductive dechlorination of 2,4,6-trichlorophenol by weak electrical stimulation. [Journal Article]
- WRWater Res 2019 Jun 27; 162:236-245
- Microbial reductive dechlorination of chlorinated aromatics frequently suffers from the long dechlorination period and the generation of toxic metabolites. Biocathode bioelectrochemical systems were …
Microbial reductive dechlorination of chlorinated aromatics frequently suffers from the long dechlorination period and the generation of toxic metabolites. Biocathode bioelectrochemical systems were verified to be effective in the degradation of various refractory pollutants. However, the electrochemical and microbial related working mechanisms for bio-dechlorination by electro-stimulation remain poorly understood. In this study, we reported the significantly improved 2,4,6-trichlorophenol dechlorination activity through the weak electro-stimulation (cathode potential of -0.36 V vs. SHE), as evidenced by the 3.1 times higher dechlorination rate and the complete dechlorination ability with phenol as the end dechlorination product. The high reductive dechlorination rate (20.8 μM/d) could be maintained by utilizing electrode as an effective electron donor (coulombic efficiency of 82.3 ± 4.8%). Cyclic voltammetry analysis of the cathodic biofilm gave the direct evidences of the cathodic respiration with the improved and positive-shifted reduction peaks of 2,4,6-TCP, 2,4-DCP and 4-CP. The optimal 2,4,6-TCP reductive dechlorination rate (24.2 μM/d) was obtained when a small amount of lactate (2 mM) was added, and the generation of H2 and CH4 were accompanied due to the biological fermentation and methanogenesis. The electrical stimulation significantly altered the cathodic biofilm structure and composition with some potential dechlorinators (like Acetobacterium) predominated. The microbial interactions in the ecological network of cathodic biofilm were more simplified than the planktonic community. However, some potential dechlorinators (Acetobacterium, Desulfovibrio, etc.) shared more positive interactions. The co-existence and possible cooperative relationships between potential dechlorinators and fermenters (Sedimentibacter, etc.) were revealed. Meanwhile, the competitive interrelations between potential dechlorinators and methanogens (Methanomassiliicoccus) were found. In the network of plankton, the fermenters and methanogens possessed the more positive interrelations. Electro-stimulation at the cathodic potential of -0.36 V selectively enhanced the dechlorination function, while it showed little influence on either fermentation or methanogenesis process. The study gave suggestions for the enhanced bioremediation of chlorinated aromatics, in views of the electro-stimulation capacity, efficiency and microbial interrelations related microbial mechanism.
- Mechanism for degradation of dichlorodiphenyltrichloroethane by mechano-chemical ball milling with Fe-Zn bimetal. [Journal Article]
- JEJ Environ Manage 2019 Jul 03; 247:681-687
- As a non-combustion technique for destruction of persistent organic pollutants, mechanochemical ball milling has attracted research attention worldwide due to high effectiveness, simplicity, and wide…
As a non-combustion technique for destruction of persistent organic pollutants, mechanochemical ball milling has attracted research attention worldwide due to high effectiveness, simplicity, and wide applicability. Previous studies have demonstrated that Fe-Zn bimetal outperformed other commonly used reagents such as CaO, Fe and Fe2O3 in mechanochemical destruction of industrial DDT. Mechanistic studies on mechanochemical destruction of persistent organic pollutants are rather limited and mechanisms may differ among reagents and chemicals. The objective of this study was to shed light on mechanisms for DDT destruction by Fe-Zn bimetal based mechanochemical treatment. A kinetics study showed that data for Fe-Zn treatment can be fitted to the Delogu model whereas that of CaO and Fe2O3 treatments followed a pseudo-second-order model. The identification of intermediates and characterization of the solid phase of the ground material revealed that dechlorination, dehydrochlorination, benzene-ring breaking, as well as splicing and condensation of small molecules occurred during the milling process. Cleavage and dehydrogenation eventually converted benzene-ring compounds into graphite and amorphous carbon.
- NanoFe3O4 accelerates anoxic biodegradation of 3, 5, 6-trichloro-2-pyridinol. [Journal Article]
- CChemosphere 2019 Jun 15; 235:185-193
- 3, 5, 6-trichloro-2-pyridinol (TCP) is a widespread organic pollutant with persistent, mobile and high antimicrobial effects. Here, nanoFe3O4 was firstly introduced into the anoxic biodegradation of …
3, 5, 6-trichloro-2-pyridinol (TCP) is a widespread organic pollutant with persistent, mobile and high antimicrobial effects. Here, nanoFe3O4 was firstly introduced into the anoxic biodegradation of TCP. It was found that nanoFe3O4 significantly accelerated TCP biodegradation. The removal rate of TCP (100 mg L-1) increased from 83.03% to 98.74% within 12 h in the presence of nanoFe3O4, and the addition of nanoFe3O4 also promoted the accumulation of CO2. Reductive dechlorination mechanism was involved in anoxic biodegradation of TCP. Molecular approaches further revealed that nanoFe3O4 distinctly induced the shifts of bacterial community. The dominant genus Ochrobactrum was converted to genus Delftia in nanoFe3O4 treatment, and the relative abundance of Delftia increased from 10.26% to 44.62%. Meanwhile, the total relative abundance of bacteria related to TCP dechlorination and degradation significantly increased in the presence of nanoFe3O4. These results indicated that nanoFe3O4 induced the enrichment of TCP-degrading bacteria to promote the anoxic biodegradation of TCP.
- Long-term mass flux assessment of a DNAPL source area treated using bioremediation. [Journal Article]
- JCJ Contam Hydrol 2019 Jun 15; :103516
- This study assessed the long-term effectiveness of bioremediation as a remedial strategy for a chlorinated, ethene dense, non-aqueous phase liquid (DNAPL) source area, consisting of a higher- and a l…
This study assessed the long-term effectiveness of bioremediation as a remedial strategy for a chlorinated, ethene dense, non-aqueous phase liquid (DNAPL) source area, consisting of a higher- and a lower-permeability zone at Alameda Point, California. The evaluation was performed over 3.7 years after cessation of active source area bioremediation using passive flux meters (PFMs), push-pull tracer tests, and soil cores. PFMs showed that total chlorinated ethene molar discharge emanating from the source area remained relatively unchanged pre-and post-bioremediation, but molar discharge compositions shifted from trichloroethene (TCE) and cis-1,2-dichloroethene (cis-DCE) to vinyl chloride (VC) and ethene dominated during post-remedial monitoring. First-order rate constants, derived from PFM data at the edge of the source area and describing the complete dechlorination of TCE at 3.7 years following active bioremediation, were approximately 1.05 yr-1, which was over three times lower than the rate 3.6 yr-1 determined using compound stable isotope analysis (CSIA). Soil cores and push-pull tracer test data showed that DNAPL volume estimates were relatively unchanged pre- and post-bioremediation due to the remaining presence of DNAPL in the lower-permeability zone. These data suggest biotransformation processes are continuing in the higher-permeability zone, whereas DNAPL in the lower-permeability zone continues to serve as a significant source of groundwater contamination. The results suggest that it will take many years under current conditions to attain the United States Environmental Protection Agency (EPA) Maximum Contaminant Levels (MCLs) cleanup objectives.
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- Photodegradation Study of Sertindole by UHPLC-ESI-Q-TOF and Influence of Some Metal Oxide Excipients on the Degradation Process. [Journal Article]
- PPharmaceutics 2019 Jun 27; 11(7)
- The evaluation of the influence of the excipients present in the pharmaceutical formulations on the drug stability is an important part of quality control of medicines. One of the most commonly appli…
The evaluation of the influence of the excipients present in the pharmaceutical formulations on the drug stability is an important part of quality control of medicines. One of the most commonly applied group of excipients are pigments, such as titanium dioxide or various forms of iron oxides, which are well-known photocatalytic agents. Therefore, the photostability of an atypical antipsychotic drug sertindole and the influence of pigments commonly used in the pharmaceutical formulations (FeOOH, Fe2O3, and TiO2) on this process were studied. The quantitative and qualitative analysis of the process was performed with the use of ultra high pressure liquid chromatography with diode array detection (UHPLC-DAD) system coupled with a high resolution hybrid electrospray ionization quadrupole time-of-flight (ESI-Q-TOF) mass spectrometer. Sertindole turned out to be a highly photolabile molecule. Overall 18 transformation products were found, mainly formed as a consequence of dechlorination, hydroxylation, and dehydrogenation. In all the experiments, except the TiO2-mediated photocatalysis, the product of chlorine substitution with a hydroxyl group was the major product. The presence of Fe2O3 and TiO2 accelerated the degradation process, while FeOOH served as its inhibitor. The experiments conducted with the use of the pharmaceutical formulations confirmed the catalytic activity of the used excipients. The exploration of the obtained phototransformation profiles with the use of principal component analysis (PCA) revealed that the presence of both iron oxides could influence the qualitative and quantitative aspect of the studied processes. In silico assessment of the properties showed that the transformation products are generally less toxic to rodents, possess lower hERG blocking potential, but could be more mutagenic than the parent molecule.