A magnetic chitosan for efficient adsorption of vanadium (V) from aqueous solution.

The all-vanadium redox flow battery (VRFB) is becoming a promising technology for large-scale energy storage due to its advantages such as scalability and flexibility. In recent years, the VRFB has been successfully developed and put into use in many countries. It is expected that the abandoned VRFB will generate a large amount of vanadium waste.

Mechanism of surfactant in trichloroethene degradation in aqueous solution by sodium persulfate activated with chelated-Fe(II).

The mechanism of surfactants in surfactant-in situ chemical oxidation (S-ISCO) coupled process for trichloroethene (TCE) degradation was firstly reported. The performance of TCE solubilization and inhibition of TCE degradation in three nonionic surfactants (TW-80, Brij-35, TX-100) in PS/Fe(II)/citric acid (CA) system was compared and TW-80 was evaluated to be the optimal surfactant in S-ISCO coupled process due to the best TCE solubilizing ability and minimal inhibition for TCE degradation (only 31.8% TCE inhibition in the presence of 1 g L TW-80 surfactant).

Enhancement of benzene degradation by persulfate oxidation: synergistic effect by nanoscale zero-valent iron (nZVI) and thermal activation.

The feasibility of an advanced oxidation process based upon sodium persulfate (SPS) activated simultaneously by heat (50 °C) and nanoscale zero-valent iron (nZVI) on benzene removal was investigated. The experimental results strongly showed the synergistic effect of thermal and nZVI activation to SPS and benzene removal was enhanced with the increase of SPS/nZVI/benzene molar ratio. Specifically, 94% of benzene could be removed in 1 hr at 50 °C at the SPS/nZVI/benzene molar ratio of 10/5/1.

Insight into CaO-based Fenton and Fenton-like systems: strategy for CaO-based oxidation of organic contaminants.

This study conducted a comparison of the CaO-based Fenton (CaO/Fe(II)) and Fenton-like (CaO/Fe(III)) systems on their benzene degradation performance. The HO, Fe(II), Fe(III), and HO variations were investigated during the benzene degradation. Although benzene has been totally removed in the two systems, the variation patterns of the investigated parameters were different, leading to the different benzene degradation patterns.

Efficient removal of trichloroethene in oxidative environment by anchoring nano FeS on reduced graphene oxide supported nZVI catalyst: The role of FeS on oxidant decomposition and iron leakage.

The performance of trichloroethene (TCE) removal was initially investigated in sodium persulfate (SPS) or potassium monopersulfate triple salt (PMS) oxidative environment by reduced graphene oxide (rGO) supported nZVI (nZVI-rGO) catalyst and further the role of sulphur by anchoring nano FeS on nZVI-rGO (FeS@nZVI-rGO) was evaluated. The high usage of oxidants and stability of FeS@nZVI-rGO catalyst were significantly improved due to the insoluble nature of this innovative catalyst by involvement of nano FeS which limited the rapid iron loss caused by the corrosion of active sites and mitigated rapid oxidants decomposition in FeS@nZVI-rGO/SPS and FeS@nZVI-rGO/PMS systems. The tests for target contaminant removal showed that over 95 % TCE could be removed at 100 mg L FeS@nZVI-rGO and 1.

Trichloroethylene degradation performance in aqueous solution by Fe(II) activated sodium percarbonate in the presence of surfactant sodium dodecyl sulfate.

The performance of trichloroethylene (TCE) degradation by sodium percarbonate (SPC) activated with Fe(II) in the presence of 3.0 g/L sodium dodecyl sulfate (SDS) as well as the role of SDS in the SPC/Fe(II) system was investigated since SDS is a common surfactant used in groundwater remediation for improving TCE dissolution to the aqueous phase. The results showed that though the introduction of SDS could inhibit the TCE degradation, the inhibiting effect was less with the increasing SDS dose.

Degradation of trichloroethylene in aqueous solution by nanoscale calcium peroxide in the Fe(II)-based catalytic environments.

In this study, nCaO was synthesized successfully and applied in the Fe(II)-based catalytic environments in investigating trichloroethylene (TCE) removal performance. nCaO with the particle sizes in the range of 50-200 nm was prepared, and it performed better for TCE removal when compared to the conventional CaO. Further experimental results showed that 70.

The performance of nCaO for BTEX removal: Hydroxyl radical generation pattern and the influences of co-existing environmental pollutants.

In this study, nano-CaO (nCaO ) was successfully synthesized and constituted the nCaO /Fe(II) system applying to remediate BTEX, which are typical mixed pollutants in contaminated groundwater. The particle size of the synthesized nCaO was 108.91 nm, and it displayed better BTEX remediation performance than that of commercial CaO .

Mechanism of carbon tetrachloride reduction in ferrous ion activated calcium peroxide system in the presence of methanol.

This study investigated the reductive initiation for the depletion of highly oxidized/perhalogenated pollutants, specifically the degradation of carbon tetrachloride (CT) was induced by adding methanol (MeOH) into a ferrous ion (Fe(II)) activated calcium peroxide (CaO) system. The results indicated that CT could be completely degraded within 20 min at CaO/Fe(II)/MeOH/CT molar ratio of 30/40/10/1 in this system. Scavenging tests suggested that both superoxide radical anion (O ) and carbon dioxide radical anion (CO ) were predominant reactive species responsible for CT destruction.

Insight on the generation of reactive oxygen species in the CaO/Fe(II) Fenton system and the hydroxyl radical advancing strategy.

Calcium peroxide (CaO) is a stable hydrogen peroxide (HO) carrier, and the CaO/Fe(II) system has been applied for treatment of various pollutants. It is commonly reported in the literature that hydroxyl radical (HO) and superoxide radical anions (O ) are the two main reactive oxygen species (ROSs) generated in the CaO/Fe(II) system. However, many of the reported results were deduced from degradation performance rather than specific testing of radical generation.

Enhanced redox degradation of chlorinated hydrocarbons by the Fe(II)-catalyzed calcium peroxide system in the presence of formic acid and citric acid.

Two carboxylic acids (formic acid (FA) and citric acid (CIT)) enhanced the Fenton process using Fe(II)-activated calcium peroxide (CP) to develop a hydroxyl (HO) and carbon dioxide radical (CO) coexistence process for the simultaneous redox-based degradation of three chlorinated hydrocarbons (CHs), namely carbon tetrachloride (CT), tetrachloroethene (PCE), and trichloroethene (TCE), was investigated. The experimental results showed that CT removal was increased while PCE and TCE degradation were decreased with the addition of FA to the Fe(II)/CP system. However, addition of CIT to the Fe(II)/CP/FA system enhanced the removal efficiency of all three contaminants.

Adsorption and mechanistic study for phosphate removal by magnetic FeO-doped spent FCC catalysts adsorbent.

The waste materials utilization has attained increasing attention due to the generation of a large number of spent materials. In the current study, a practical magnetic adsorbent (FeO-doped spent Fluid Catalytic Cracking catalysts, abbreviated as FCC@(Fe)-O) was prepared, liable to be separated. The batch experiments were employed to investigate the phosphate removal behavior.

The impact of surface properties and dominant ions on the effectiveness of G-nZVI heterogeneous catalyst for environmental remediation.

The surface properties of nanocomposites are influenced by the existence of inorganic species that may affect its performance for specific catalytic applications. The impact of different ionic species on particular catalytic activity had not been investigated to date. In this study, the surface charge (zeta potential) of graphene-oxide-supported nano zero valent iron (G-nZVI) was tested in definitive cationic (Na, K, Ca and Mg) and anionic (Br, Cl, NO, SO, and HCO) environments.

Enhanced degradation of trichloroethylene in oxidative environment by nZVI/PDA functionalized rGO catalyst.

Nano zero-valent iron (nZVI) particles with higher reactivity have been recognized as more efficient catalysts than Fe(II) for the groundwater remediation. The rapid emergence of novel catalyst supports efficiently prevent the rapid aggregation of nZVI and further improve catalytic reactivity. However, the lack of ability to avoid the potential oxidation of bare nZVI-support structure in air environment hinders its wider application in the actual contaminated sites.

Enhanced effect of EDDS and hydroxylamine on Fe(II)-catalyzed SPC system for trichloroethylene degradation.

This study presents a performance comparison of Fe(II)-catalyzed sodium percarbonate (SPC), Fe(II)-EDDS-catalyzed SPC, and of the innovative hydroxylamine hydrochloride (HA)-Fe(II)-EDDS-catalyzed SPC for the degradation of trichloroethylene (TCE) in water. TCE degradation was greater in the Fe(II)-EDDS-catalyzed SPC system compared to the Fe(II)-catalyzed SPC system, indicating the effectiveness of adding EDDS as an enhancement factor for the removal of TCE. Moreover, TCE degradation was faster in the HA-Fe(II)-EDDS-catalyzed SPC system compared to the Fe(II)-EDDS-catalyzed SPC system, illustrating that HA can play a synergistic role in TCE degradation.

Degradation of trichloroethylene in aqueous solution by rGO supported nZVI catalyst under several oxic environments.

The reduced graphene oxide (rGO) supported nano zero-valent iron (nZVI) (nZVI-rGO) was synthesized successfully and applied in the several oxic environments to remove trichloroethylene (TCE). The nZVI-rGO had a better catalytic performance than bare nZVI for the TCE removal. Both aggregation of nZVI and agglomeration of rGO were in part prevented by loading the nZVI nanoparticles on the rGO sheet.

Efficient transformation in characteristics of cations supported-reduced graphene oxide nanocomposites for the destruction of trichloroethane.

Experiments were conducted to investigate the use of graphene-oxide supported metallic nanocomposites for improving the degradation of trichloroethane (TCA) by sodium percarbonate (SPC). Two methods of production, chemical reduction (CR) and solvo-thermal (ST), were tested for preparation of single (Fe) and binary (Fe-Cu) nanocomposites supported by reduced graphene oxide (rGO). A variety of analytical techniques including N2 adsorption Brunauer-Emmett-Teller (BET), x-ray diffraction (XRD), fourier-transfrom infrared spectroscopy (FTIR), and transmisison electron microscopy (TEM) were applied to characterize the physicochemical and microstructural properties of the synthesized nanocomposites.

Application of ascorbic acid to enhance trichloroethene degradation by Fe(III)-activated calcium peroxide.

The enhancement effect of an environmentally friendly reducing agent, ascorbic acid (AA), on trichloroethene (TCE) degradation by Fe(III)-activated calcium peroxide (CP) was evaluated. The addition of AA accelerated the transformation of Fe(III) to Fe(II), and the complexation of Fe(III)/Fe(II) with AA and its products alleviated the precipitation of dissolved iron. These impacts enhanced the generation of reactive oxygen species (ROSs).

Enhanced degradation of carbon tetrachloride by sodium percarbonate activated with ferrous ion in the presence of ethyl alcohol.

In this study, the degradation performance of carbon tetrachloride (CT) by sodium percarbonate (SPC) activated with Fe(II) in the presence of ethyl alcohol (EA) was investigated. The experimental results showed that CT could be readily degraded and the optimal EA/Fe(II)/SPC/CT molar ratio for CT reduction was 100/50/20/1. Superoxide radical anion ( ) and hydroxyethyl radical (CHCHOH, HER) were the predominant radical species responsible for CT degradation and EA could regulate the generation of and HER in the system.

Benzene oxidation by Fe(III)-catalyzed sodium percarbonate: matrix constituent effects and degradation pathways.

Complete degradation of benzene by the Fe(III)-activated sodium percarbonate (SPC) system is demonstrated. Removal of benzene at 1.0 mM was seen within 160 min, depending on the molar ratios of SPC to Fe(III).

The destruction of benzene by calcium peroxide activated with Fe(II) in water.

The ability of Fe(II)-activated calcium peroxide (CaO) to remove benzene is examined with a series of batch experiments. The results showed that benzene concentrations were reduced by 20 to 100% within 30 min. The magnitude of removal was dependent on the CaO/Fe(II)/Benzene molar ratio, with much greater destruction observed for ratios of 4/4/1 or greater.

Enhanced effect of HAH on citric acid-chelated Fe(II)-catalyzed percarbonate for trichloroethene degradation.

This work demonstrates the impact of hydroxylamine hydrochloride (HAH) addition on enhancing the degradation of trichloroethene (TCE) by the citric acid (CA)-chelated Fe(II)-catalyzed percarbonate (SPC) system. The results of a series of batch-reactor experiments show that TCE removal with HAH addition was increased from approximately 57 to 79% for a CA concentration of 0.1 mM and from 89 to 99.

Investigation into the nitrate removal efficiency and microbial communities in a sequencing batch reactor treating reverse osmosis concentrate produced by a coking wastewater treatment plant.

In this study, a biological denitrifying process using a sequencing batch reactor (SBR) was employed to treat reverse osmosis (RO) concentrate with high conductivity produced from a coking wastewater plant. From the results, the average removal efficiencies for chemical oxygen demand, total nitrogen, and nitrate were 79.5%, 90.

Application of calcium peroxide activated with Fe(II)-EDDS complex in trichloroethylene degradation.

This study was conducted to assess the application of calcium peroxide (CP) activated with Fe(II) chelated by (S,S)-ethylenediamine-N,N'-disuccinic acid (EDDS) to enhance trichloroethylene (TCE) degradation in aqueous solution. It was indicated that EDDS prevented soluble iron from precipitation, and the optimum molar ratio of Fe(II)/EDDS to accelerate TCE degradation was 1/1. The influences of initial TCE, CP and Fe(II)-EDDS concentration were also investigated.

Enhanced degradation of trichloroethene by calcium peroxide activated with Fe(III) in the presence of citric acid.

Trichloroethene (TCE) degradation by Fe(III)-activated calcium peroxide (CP) in the presence of citric acid (CA) in aqueous solution was investigated. The results demonstrated that the presence of CA enhanced TCE degradation significantly by increasing the concentration of soluble Fe(III) and promoting HO generation. The generation of HO• and O• in both the CP/Fe(III) and CP/Fe(III)/CA systems was confirmed with chemical probes.