Removal Of Ether Research Articles

Rapid removal of decabromodiphenyl ether by mechanochemically prepared submicron zero-valent iron with FeC2O4·2 H2O layers: Kinetics, mechanisms and pathways

The utilization of nano zero-valent iron (nZVI) in polybrominated diphenyl ethers remediation has been studied extensively. However, challenges in balancing cost and reactivity have been encountered. A submicron zero-valent iron coated with FeC2O4·2 H2O layers (OX-smZVI) was synthesized via a mechanochemical method, aiming to resolve this contradiction. Characterization via SEM, TEM, and XPS confirmed the structure as FeC2O4·2 H2O coated iron lamellate with a surface area 24-fold higher than ball-milled zero-valent iron (smZVI). XRD highlighted an Fe/C eutectic in OX-smZVI, boosting its electron transfer capacity. Decabromodiphenyl ether degradation by OX-smZVI follows a two-stage process, with initial degradation by FeC2O4·2 H2O and a subsequent phase dominated by electron transfer. OX-smZVI exhibits a 4.52–34.40 times faster BDE209 removal rate than nZVI and scaled-up OX-smZVI displayed superior reactivity with preparation costs only 1/680 of nZVI. Given its enhanced reactivity and cost-efficiency, OX-smZVI emerges as a promising replacement for nZVI.

Enhanced Degradation of Decabromodiphenyl Ether via Synergetic Assisted Mechanochemical Process with Lithium Cobalt Oxide and Iron

The removal of decabromodiphenyl ether (BDE 209), as a typical persistent organic pollutant (POP), is of worldwide concern. Mechanochemical (MC) processes are promising methods to degrade environmental pollutants, most of which use a single grinding reagent. The performance of MC processes with co-milling agents still needs to be further verified. In this study, an efficient MC treatment with combined utilization of lithium cobalt oxide (LiCoO2) and iron (Fe) as co-milling reagents for BDE 209 degradation was investigated. The synchronous action of LiCoO2 and Fe with a LiCoO2/Fe/Br molar ratio of 1.5:1.67:1 and a ball-to-powder ratio of 100:1 led to almost thorough-paced abatement and debromination of BDE 209 within 180 min using a ball milling rotation speed of 600 rpm. The reduction in particle sizes and the destruction of crystal structure in mixture powders with the increase in milling time induced the enhanced degradation of BDE 209, as characterized by scanning electron microscopy (SEM) and X-ray diffraction (XRD). The X-ray photoelectron spectroscopy (XPS) characterization showed that the valence state of Co was converted from Co(III) to Co(II), and Fe(0) was changed to Fe(III) when treated with an MC process. This indicated that the reductive debromination of BDE 209 by Fe and the following oxidative degradation of debrominated products by LiCoO2 were integrated in a concerted way. It proved the removal of BDE 209 via an MC treatment. The full breakage of C-Br and C-O bonds in BDE 209 was confirmed by Fourier transform-infrared spectrometry (FT-IR) spectra, and a possible abatement pathway was also proposed based on the identified intermediate products using gas chromatography–mass spectrometry (GC-MS). These obtained results indicated that a combination of LiCoO2 and Fe as co-milling reagents is promising in the MC treatment of toxic halogenated pollutants like BDE 209.

Magnetic Fe-doped silicon carbide induced microwave activated persulfate for decabromodiphenyl ether removal: Mechanism and unique degradation pathway

In this work, the magnetic nanocomposite Fe@SiC was prepared by a hydrothermal method and determined by SEM, XRD, XPS, FTIR and VNA. Fe3O4 particles were loaded onto SiC with great success, and the synthesized composites had favorable microwave absorption properties. Fe@SiC was used to activate persulfate in a microwave field for the degradation of BDE209 in soil. Specifically, the synergistic interaction between microwaves and Fe@SiC showed excellent catalytic performance in activating PS to degrade BDE209 (90.1% BDE209 degradation in 15 min). The presence of •OH, O2•− and 1O2 was demonstrated based on quench trapping and EPR experiments. LC‒MS was applied to determine the intermediates and propose the possible degradation pathway for BDE209 in the MW/Fe@SiC/PS system, and it was found that BDE209 produced almost no lower brominated diphenyl ethers. Therefore, the toxicity of BDE209 was found to be reduced using toxicity assessment software. Overall, this work provides an effective approach for the degradation of BDE209 in environmental remediation.

A general review on the application of adsorption and oxidation combined processes on methyl tert-butyl ether removal

A general review on the application of adsorption and oxidation combined processes on methyl tert-butyl ether removal

Remediation of polybrominated diphenyl ethers contaminated soil in the e-waste disposal site by ball milling modified zero valent iron activated persulfate

Hydrophobic organic compounds (HOCs) in e-waste disposal sites are difficult to remove effectively. There is little reported about zero valent iron (ZVI) coupled with persulfate (PS) to achieve the removal of decabromodiphenyl ether (BDE209) from soil. In this work, we have prepared the flake submicron zero valent iron by ball milling with boric acid (B-mZVIbm) at a low cost. Sacrifice experiments results showed that 56.6% of BDE209 was removed in 72 h with PS/B-mZVIbm, which was 2.12 times than that of micron zero valent iron (mZVI). The morphology, crystal form, atomic valence, composition, and functional group of B-mZVIbm were determined by SEM, XRD, XPS, and FTIR, and the results indicated that the oxide layer on the surface of mZVI is replaced by borides. The results of EPR indicated that hydroxyl radical and sulfate radical played the dominant role in the degradation of BDE209. The degradation products of BDE209 were determined by gas chromatography-mass spectrometry (GC-MS), accordingly, the possible degradation pathway was further proposed. The research suggested that ball milling with mZVI and boric acid is a low-cost means of preparing highly active zero valent iron materials. And the mZVIbm has promising applications in improving the activation efficiency of PS and enhancing the removal of the contaminant.

Enhanced Methyl Tert-Butyl Ether Removal by Mixed Consortium: Performance and Adaptability

Methyl tert-butyl ether (MTBE) is widely used as a gasoline additive with toxicity and carcinogenicity, and has caused environmental pollution worldwide. Biodegradation is a promising method for the removal of MTBE from contaminated sites. In this paper, three strains with high adaptability and different degrading characteristics to MTBE were cultured. The kinetic models were established to systematically simulate the biodegradation of MTBE by various strains at different concentrations. Moreover, the removal of MTBE in a synergistic system containing a mixture of three pure strains was studied. The mixed consortium enhanced MTBE removal at high concentrations (30–50 mg/L), and the degradation efficiency was increased by about 20% compared to pure strains at a concentration of 30 mg/L. Further, the mixed consortium degraded MTBE nearly three times faster than any of the individual, indicating that the co-cultures of three pure cultures improved both efficiency and the rate of MTBE biodegradation. In addition, it was found that the mixed consortium effectively removed MTBE in the presence of other gasoline components, and exhibited stronger adaptability, especially at low or high temperatures. This study supports the cultivation of a mixed consortium to remediate MTBE-contaminated environments, either as a single substrate or in environments containing other gasoline components.

Synergistic removal of decabromodiphenyl ether by sulfurized zero-valent iron coupling with microbacterium in the presence of heavy metals: Biochemical degradation process and mechanism

Microorganisms and sulfurized nano zero-valent iron (S-nZVI) were widely used for the remediation of contaminants in e-waste sites. However, it is elusive whether microorganisms and S-nZVI have a synergistic effect in the removal of heavy metals (HMs) and organic complex pollutants. In this work, the removal performance and mechanisms of HMs-decabromodiphenyl ether combined pollutants (HMs-BDE-209) in Microbacterium Y2 (MY2)/S-nZVI co-incubation system (MY2 @S-nZVI) was investigated. The results showed that simultaneous removal of HMs-BDE-209 by MY2 or S-nZVI alone was difficult. However, the synergistic removal of HMs-BDE-209 was observed in MY2 @S-nZVI system. Specially, Cr(VI) ions significantly inhibited the removal of BDE-209 by MY2 or S-nZVI. Nevertheless, the rapid immobilization of Cr(VI) ions with S-nZVI not only inhibited the generation of ROS induced by S-nZVI, but also reduced the cytotoxicity of Cr(VI) toward MY2, leading to achieving synergistic BDE-209 removal in MY2 @S-nZVI/Cr(VI) system. Unexpectedly, the bio-degradation mainly accounted for 78.8–88.4% removal of BDE-209 in MY2 @S-nZVI system in the presence of Cr(VI). In contrast, the chemical degradation (95% of BDE-209 removal) dominated the degradation of BDE-209 in MY2 @S-nZVI/Ni(Ⅱ) system due to the fact that Ni(Ⅱ) could be quickly reduced by S-nZVI to form highly reactive Ni0/Fe0 bimetals. The findings of this study are conducive to understanding the complicated mechanism in the remediation of HMs and organic combined pollutants by using microorganisms and S-nZVI hybrid technologies.

Effects of operational parameters on methyl tert-butyl ether removal by permeable reactive barrier from polluted waters

Background: Recalcitrant organics remediation from water resources continues to be a significant environmental problem and there is a continued effort to demonstrate practicable and economical treatment options for pollution removal. Methods: In this study, the efficiency of the permeable reactive barrier (PRB) in a column reactor using zero-valent iron (ZVI) particles and sand mixture in the removal of methyl tert-butyl ether (MTBE) from aquatic phases was investigated. The system performance was MTBE removal while initial pH, reaction time, pollutant content, catalyst load, hydraulic loading rate (HLR), and the reaction rate constant were independent variables. Results: The results showed that the process efficiency decreased by increasing pH, HLR, and pollutant concentration. In this case, the optimal conditions were obtained at pH=7, HLR=0.23 m3 /m2 ·d, and C0=1 mg/L, which achieved a remarkable removal efficiency up to 90.32%. The high nitrate concentrations and hardness as intervening factors reduced process efficiency to less than 44.61 and 51.4%, respectively. The lack of interfering factors had a considerable effect on the reaction rate of MTBE reduction, which is approximately 2.65 and 4.11 times higher than that in the presence of calcium hardness and nitrate, respectively. Conclusion: The PRB technology can be suggested as a reliable and robust system to remediate groundwater containing hydrocarbons based on filling media and hydraulic conditions.

Enhanced reductive debromination of decabromodiphenyl ether by organic-attapulgite supported Fe/Pd nanoparticles: Synergetic effect and mechanism

Effective removal of polybrominated diphenyl ethers (PBDEs) from the environment is essential for the ecosystem and human health. Reductive debromination of PBDEs by nanoscale zerovalent iron (nZVI) has become an important technology. However, the agglomeration and low persistence catalytic activity of nZVI particles have become urgent problems to be improved. Herein, we report the first application of a new organo-attapulgite (OA) supported Fe/Pd nanoparticles (OA-Fe/Pd) composite for decabromodiphenyl ether (BDE209) removal. BDE209 was efficiently removed using OA-Fe/Pd with a reaction rate that was 9.97 times greater than that of the nZVI due to the synergetic effect of support material OA and Pd loading. OA could prevent nZVI particles from agglomeration and adsorb BDE209 molecules to its surface. Pd could supply atomic hydrogen and also prevent the oxidation of nZVI particles. The degradation of BDE209 by OA-Fe/Pd was affected by many factors and followed pseudo first-order kinetics. The degradation of BDE209 by OA-Fe/Pd underwent a stepwise debromination manner with the H-transfer dominant mechanism. BDE209 (25 mg∙L-1) could be degraded to penta-BDEs to diphenyl ether (DE) by 3.0 g∙L-1 OA-Fe/Pd within 240 min under neutral condition. This study provides some inspiration for improving the removal efficiency of PBDEs with nZVI-based materials.

Enhancement effect of nanoscale zero-valent iron addition on microbial degradation of BDE-209 in contaminated mangrove sediment

Chemical and biological methods have been employed to remedy polybrominated diphenyl ether contamination, but the removal of decabromodiphenyl ether (BDE-209) by either method still has limitations. The present study aims to evaluate the combined effect of nanoscale zero-valent iron (nZVI) (from 0.1 to 10%) reduction and microbial debromination on BDE-209 removal in mangrove sediments under an anaerobic condition. During the 12-months incubation, nZVI significantly enhanced BDE-209 removal, with 17.03% to 41.99% reduction in sterilized sediments. The reduction was even higher in non-sterilized sediments with living indigenous microorganisms, achieving 15.80%, 33.50%, 55.83% and 66.95% removal of BDE-209 at 0 (control without nZVI), 0.1%, 1% and 10% nZVI, respectively. In control sterilized sediments, no debromination was found, and debromination occurred according to spiked levels of nZVI, with BDE-153 being the dominant congener. The concentrations of debrominated congeners in non-sterilized sediments also increased with nZVI levels, but were significantly higher than the respective sterilized sediment. The relative proportions of different debrominated congeners in non-sterilized sediments depended on nZVI levels, with BDE-99 being the dominant congener in low nZVI amended sediments but shifted to BDE-153 under high nZVI. Higher concentrations of ferrous iron (Fe2+) were detected in both sterilized and non-sterilized sediments spiked with more nZVI, and their concentrations significantly correlated with BDE-209 removal. Growth of total bacteria in sediments with 1% and 10% nZVI was inhibited within first two months, but their numbers resumed to that in the control at the end of 12 months. The present study demonstrates the synergy between chemical and microbiological methods, and a combination of nZVI and indigenous microorganisms could be an efficient and feasible mean to remedy BDE-209 in contaminated sediments.

Photocatalytic activation of C-Br bond on facet-dependent BiOCl with oxygen vacancies

As typical persistent organic pollutants, polybrominated diphenyl ethers (PBDEs) have aroused high environmental concern due to their toxicity and recalcitrant degradation. Herein, the photocatalytic decabromodiphenyl ether (BDE209) removal performance was evaluated firstly on facet-dependent BiOCl with oxygen vacancies under irradiation (>360 nm). The results revealed that BDE209 was rapidly debrominated on {001} BiOCl with a reaction rate 4.4 times greater than that on {010} BiOCl under oxygen-free environment. Such a degradation order is completely opposite to that of Rhodamine B (RhB) degradation. This enhanced reduction is mainly attributed to the abundant oxygen vacancies on {001} facet of BiOCl, which act as adsorption sites for BDE209 to achieve C-Br bond activation efficiently. Meanwhile, debrominated products via meta-position have the highest proportion than that via ortho- and para-position in the first step. Therefore, a position-selective multi-electrons reduction mechanism is hypothesized. This study provides a new sight on C-X bond activation of halogenated aromatics by inducing oxygen vacancies on specific facets.

Kinetic modeling of Methyl Tert-Butyl Ether (MTBE) removal by bacterial isolated from contaminated soils

ABSTRACT Methyl Tert-Butyl Ether(MTBE) is among oxygenised additives to gasoline, which has high solubility and leads to pollution of water resources. So far, the microbial species affecting the of high MTBEconcentrationsremoval have been less investigated. This study aimed to remove high concentrations of MTBEusing isolated bacteriafrom contaminatedsoil with petroleum compounds in southern regions of Iran and determine their kinetics. After isolating the bacteria and determining their growth in different concentrations, the effects of the following parameters on the removal percentage were examined: incubation time = 1–7 days, pH = 5.0–7.0, and 9.0, initial MTBE concentration = 1000–5000 mg/L, and C: N:P. Then, the four strains with high efficiency were selected, and their kinetic were analysed by zero-order, first-order, and second-order models. The results showed that the highest growth in MTBE concentration (50,000 mg/L) was observed for Acinetobacter sp, Bacillus sp, Ochrobactrum sp, and Sphingomonas sp. after four days. Then, Ochrobactrum sp.was used as a pure strain as well as a microbial consortium for the next steps, including the effects of nutrient ratio and initial MTBE concentration. In this study, the optimal conditions for incubation time and the initial MTBE concentration were 72 hours and 5000 mg/L, respectively. The kinetic modeling indicated that the second-order model (R2 = 0.95, Root Mean Squared Error = 0.012) and the Micheal-Menten model (R2 = 0.99) were the best modelfor MTBE biodegradation. Overall, the results indicated that pure Ochrobactrum sp. and a microbial consortium consisting of resistant bacteria at high MTBEconcentrations could remove MTBE> 90%.

Enhancement of microbial redox cycling of iron in zero-valent iron oxidation coupling with deca-brominated diphenyl ether removal

Iron-redox cycling microorganisms are important for understanding the biogeochemical iron and play key roles in zero-valent iron (ZVI) mediated environmental bioremediation. Their influence on ZVI oxidation coupling with organic contaminant removal is of particular interest but is still poorly understood. The objective of this research was to study microbial redox cycles of iron in ZVI oxidation and deca-brominated diphenyl ether (deca-BDE) removal. It was found that iron-oxidizing bacteria (IOB) enhanced ZVI oxidation by using iron as the sole electron donor. Iron-reducing bacteria (IRB) with high activity of Fe (III) reduction, also significantly accelerated rather than inhibited ZVI oxidation. ZVI oxidation activity was increased from 3.42% to 24.28% by IOB and 19.49% by IRB. When deca-BDE was present in the medium, ZVI oxidation activity by IOB and IRB was increased from 2.67% to 48.33% and 64.33%, respectively. However, no co-accelerating effect of IOB and IRB occurred but rather a neutralizing influence on ZVI oxidation was detected with iron-redox cycling bacteria (IORB). ZVI oxidation activity by IORB only increased to 13.14% and 37.0% in the absence and presence of deca-BDE, respectively. Meanwhile, IRB also exhibited the highest removal activity of deca-BDE. Approximately 71.67% of deca-BDE was removed by IRB, compared to 18.91% by IOB and 43.24% by IORB. Deca-BDE significantly influenced the effects of iron-metabolizing microorganisms on ZVI oxidation by altering the composition of microbial communities. Pseudomonas, Paenibacillus, and Sporolactobacillus were the key genera influencing ZVI oxidation and deca-BDE removal. Sporolactobacillus was firstly reported to be able to stimulate both ZVI oxidation and deca-BDE removal. Pseudomonas accelerated ZVI oxidation but had no significant contribution to deca-BDE removal. However, Paenibacillus inhibited both Fe(III) reduction and deca-BDE removal. It is expected that continuous integration of ZVI oxidation and organic contaminant removal can be achieved by regulating the key genera in iron-metabolizing microbial communities.

Ligand Effects in Calcium Catalyzed Ketone Hydroboration

The first “naked” (Lewis base‐free) cationic Ca amidinate complex [tBuAmDIPPCa(C6H6)]+[B(C6F5)4]– was prepared in 62 % yield {tBuAmDIPP = tBuC(N–DIPP)2; DIPP = 2,6‐diisopropylphenyl} by reaction of [tBuAmDIPPCaH]2 with [Ph3C]+[B(C6F5)4]– in chlorobenzene. The ether‐free complex tBuAmDIPPCaN(SiMe3)2 was obtained by removal of diethyl ether from its ether adduct. Crystal structures show that the amidinate ligand in both complexes is N,Aryl‐chelating. In this coordination mode the bulk of the amidinate ligand is comparable to that of a DIPP‐substituted β‐diketiminate ligand. Isomers with N,N‐coordinating amidinate ligands are circa 15 kcal/mol higher in energy and this coordination mode is only present in case additional ether ligands compensate for energy loss or in case of space limitation at the metal, e.g. in homoleptic (tBuAmDIPP)2Ca. A series of four Ca amidinate complexes, tBuAmDIPPCaX, were tested in the catalytic hydroboration of ketones and aldehydes by pinacolborane (HBpin). Catalytic activities increase for X– = I– < B(C6F5)4– < (Me3Si)2N– ≈ H–. For catalysts with unreactive anions, like I– or B(C6F5)4–, catalyst performance increases with the Lewis acidity of the metal and a mechanism is proposed in which HBpin and ketone coordinate to the Ca2+ ion which is followed by direct hydroboration. The more active catalysts with X– = (Me3Si)2N– or H– likely operate through a mechanism which involves intermediate metal hydride (or borate) complexes.

Removal of Residual Toluene and Methyl Tertiary Butyl Ether from Amorphous Paclitaxel by Simple Rotary Evaporation with Alcohol Pretreatment

In this study, a drying method was developed for effective removal of residual solvents from toluene- or methyl tertiary butyl ether-induced amorphous paclitaxel. By simple rotary evaporation with alcohol pretreatment, there was sufficient removal of the residual toluene, methyl tertiary butyl ether, methanol, and ethanol concentrations of paclitaxel to bring them below the ICH-specified values (890, 5000, 3,000, and 5,000 ppm). In addition, SEM analysis and ultrasonic treatment revealed that residual solvent removal was associated with the formation of pores on the surface of the sample because of the high vapor pressure of the toluene-alcohol mixture or the methyl tertiary butyl ether-alcohol mixture and hydrogen bonding between the solvent and the alcohol.

Decomposition of dioxin-like components in a DBD reactor combined with Hg/Ar electrodeless ultraviolet

A new combined reactor with Hg/Ar electrodeless ultraviolet (EDUV) activated by DBD for 3,4-dichlorodiphenyl ether abatement is presented. The effect of specific input energy and feeding gas component on 3,4-dichlorodiphenyl ether removal efficiency has been explored. Compared with a single DBD system, this new combined process performed a significant promotion on 3,4-dichlorodiphenyl ether abatement. Experiment results verified that active oxygen clearly contributed to the synergistic activity of DBD-EDUV system. Results of emission spectra showed that UV radiation of 253.7 nm could be detected in the DBD-EDUV system. Further, the products of DBD-EDUV process were analyzed via gas chromatography-mass spectrometer (GC-MS) to reveal involved decomposition mechanism.

In-situ degradation of polybrominated diphenyl ethers from thermal desorption off-gas over structured Fe-based/γ-Al2O3/Al plate-type catalyst

Thermal desorption was an efficient method for removal of decabromodiphenyl ether (BDE-209) from contaminated soil, but some less brominated diphenyl ethers (tri- to hepta-BDEs) with high toxicity were detected in the effluent gas. Herein, a novel anodic alumina supported Fe-based catalyst was developed and applied for in-situ degradation of gaseous polybrominated diphenyl ethers (PBDEs). The produced Fe/γ-Al2O3/Al catalyst was able to degrade PBDEs in the effluent gas, while a low activity with degradation efficiency of 70.1% was observed. As such, Cu was added into the Fe-based catalyst, and the effects of Cu loading on gaseous PBDEs degradation were systematically examined. A proper copper loading was found to increase the active Fe3O4 sites, thus improving the catalytic activity. Meanwhile, the degradation of gaseous PBDEs by Fe-based catalysts follows a pseudo-first-order model. A 90.2% PBDEs degradation efficiency was achieved at 375 °C on the optimized Fe/Cu/γ-Al2O3/Al catalyst, which demonstrated that the anodic alumina supported Fe and Cu was an excellent catalyst for gaseous PBDEs degradation system. Thus, this study provides a promising method and catalyst to achieve in-situ degradation of gaseous PBDEs.

Bioremediation of gaseous methyl tert-butyl ether by combination of sulfuric acid modified bagasse activated carbon-bone biochar beads and Acinetobacter indicus screened from petroleum contaminated soil

Combination of sulfuric acid modified bagasse activated carbon-bone biochar beads and Acinetobacter indicus screened from petroleum contaminated soil was the best condition for gaseous methyl tert-butyl ether (MTBE) removal. It was found that H2SO4 modified bagasse AC in powder form had higher adsorption capacity (989.33 mg g−1) than that in bead form (1.94 mg g−1). In addition, bone biochar in powder form (3.51 mg g−1) also had higher adsorption capacity than that in bead form (1.63 mg g−1). This was the fact that material beads contained high moisture content that inhibited the penetration of gaseous MTBE into the material. And a mixed material of H2SO4 modified bagasse AC-bone biochar beads had the highest adsorption capacity (2.22 mg g−1) compared to individual H2SO4 modified bagasse AC beads (1.94 mg g−1) and bone biochar beads (1.63 mg g−1) due to a mixed material had more rough surface and high surface area on its material. So, gaseous MTBE can penetrate through this material more easily. Although the maximum adsorption capacity of H2SO4 modified bagasse AC in powder form was the highest but microorganism cannot sustain and survive in this form for a long time. Therefore, the material beads were more suitable for microorganism to grow and degrade gaseous MTBE. Microorganism can degrade MTBE and caused no secondary wastes. Moreover, A. indicus was a novel strain for MTBE removal that has not been previously reported. Therefore, a combination of A. indicus-mixed material beads was a good choice for MTBE removal in a biofilter system.

The degradation of decabromodiphenyl ether in the e-waste site by biochar supported nanoscale zero-valent iron /persulfate

Biochar supported nano zero-valent iron (BC-nZVI) synthesized through liquid phase reduction method was used to activate persulfate (PS) for the removal of decabromodiphenyl ether (BDE209) in the soil. The morphology, structure and composition of BC-nZVI were determined by SEM, XRD, XPS and FTIR. Batch experiments were carried out to investigate the effect of different factors, such as the molar ratio of PS to BC-nZVI, pH value of PS solution and reaction temperature, on the degradation efficiency of BDE209. Results showed that when the molar ratio of PS/BC-nZVI was 3:1, pH value was 3, reaction temperature was 40 °C, 82.06% of BDE209 could be removed within 240 min. The process fitted pseudo-first-order kinetics model well and the apparent activation energy (Ea) was 48.92 kJ mol−1, indicating that the process was controlled by surface reaction. The quenching experiments showed that ·SO4− was predominate radical species in the degradation process in acid and neutral condition. However, ·OH played more important role in alkaline condition. GC-MS was used to determine the reaction products for inferring the degradation pathway of BDE209 in soil by BC-nZVI/PS system.

MgAl-Layered-Double-Hydroxide/Sepiolite Composite Membrane for High-Performance Water Treatment Based on Layer-by-Layer Hierarchical Architectures.

One of the major challenges in the removal of organic pollutants is to design a material with high efficiency and high flux that can remove both cationic and anionic dyes, oil-in-water (O/W) emulsion and heavy metal ions. Herein, we constructed novel chemically stabilized MgAl-layered-double-hydroxide/sepiolite (MgAl-LDH/Sep) composite membranes via 3D hierarchical architecture construction methods. These membranes were analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM) and X-ray diffraction (XRD), etc. Benefiting from the presence of hydrophilic functional groups on the surface of the film, the membranes show an enhanced water flux (~1200 L·m−2 h−1), while keeping a high dyes rejection (above 99.8% for anionic and cationic dyes). Moreover, the CA membrane coupled with MgAl-LDH/Sep exhibits a multifunctional characteristic for the efficient removal of mesitylene (99.2%), petroleum ether (99.03%), decane (99.07%), kerosene (99.4%) and heavy metal ion in water due to the layer-by-layer sieving. This hierarchical architecture is proved to have excellent environmental and chemical stability. Therefore, the membrane has potential in the treatment of sewage wastewater.