Optimized bimetallic ratios for durable membrane catalyst-film reactors in treating nitrate-polluted water.

Nitrate contamination of surface and ground water is a significant global challenge. Most current treatment technologies separate nitrate from water, resulting in concentrated wastestreams that need to be managed. Membrane Catalyst-film Reactors (MCfR), which utilize in-situ produced nanocatalysts attached to hydrogen-gas-permeable hollow-fiber membranes, offer a promising alternative for denitrification without generating a concentrated wastestream. In hydrogen-based MCfRs, bimetallic nano-scale catalysts reduce nitrate to nitrite and then further to di-nitrogen or ammonium. This study first investigated how different molar ratios of indium-to-palladium (In:Pd) catalytic films influenced denitrification rates in batch-mode MCfRs. We evaluated eleven In-Pd bimetallic catalyst films, with In:Pd molar ratios from 0.0029 to 0.28. Nitrate-removal exhibited a volcano-shaped dependence on In content, with the highest nitrate removal (0.19 mgNO3--N-min-1 L-1) occurring at 0.045 mol In/mol Pd. Using MCfRs with the optimal In:Pd loading, we treated nitrate-spiked tap water in continuous-flow for >60 days. Nitrate removal and reduction occurred in three stages: substantial denitrification in the first stage, a decline in denitrification efficiency in the second stage, and stabilized denitrification in the third stage. Factors contributing to the slowdown of denitrification were: loss of Pd and In catalysts from the membrane surface and elevated pH due to hydroxide ion production. Sustained nitrate removal will require that these factors be mitigated.

Comparing methods to deposit Pd-In catalysts on hydrogen-permeable hollow-fiber membranes for nitrate reduction.

Catalytic hydrogenation of nitrate in water has been studied primarily using nanoparticle slurries with constant hydrogen-gas (H2) bubbling. Such slurry reactors are impractical in full-scale water treatment applications because 1) unattached catalysts are difficult to be recycled/reused and 2) gas bubbling is inefficient for delivering H2. Membrane Catalyst-film Reactors (MCfR) resolve these limitations by depositing nanocatalysts on the exterior of gas-permeable hollow-fiber membranes that deliver H2 directly to the catalyst-film. The goal of this study was to compare the technical feasibility and benefits of various methods for attaching bimetallic palladium/indium (Pd/In) nanocatalysts for nitrate reduction in water, and subsequently select the most effective method. Four Pd/In deposition methods were evaluated for effectiveness in achieving durable nanocatalyst immobilization on the membranes and repeatable nitrate-reduction activity: (1) In-Situ MCfR-H2, (2) In-Situ Flask-Synthesis, (3) Ex-Situ Aerosol Impaction-Driven Assembly, and (4) Ex-Situ Electrostatic. Although all four deposition methods achieved catalyst-films that reduced nitrate in solution (≥ 1.1 min-1gPd-1), three deposition methods resulted in significant palladium loss (>29%) and an accompanying decline in nitrate reactivity over time. In contrast, the In-Situ MCfR-H2 deposition method had negligible Pd loss and remained active for nitrate reduction over multiple operational cycles. Therefore, In-Situ MCfR-H2 emerged as the superior deposition method and can be utilized to optimize catalyst attachment, nitrate-reduction, and N2 selectivity in future studies with more complex water matrices, longer treatment cycles, and larger reactors.

Inhibition of biofouling on reverse osmosis membrane surfaces by germicidal ultraviolet light side-emitting optical fibers.

Biofouling of membrane surfaces poses significant operational challenges and costs for desalination and wastewater reuse applications. Ultraviolet (UV) light can control biofilms while reducing chemical usage and disinfection by-products, but light deliveries to membrane surfaces in spiral wound geometries has been a daunting challenge. Thin and flexible nano-enabled side-emitting optical fibers (SEOFs) are novel light delivery devices that enable disinfection or photocatalytic oxidation by radiating UV light from light-emitting diodes (LEDs). We envision SEOFs as an active membrane spacer to mitigate biofilm formation on reverse osmosis (RO) membranes. A lab-scale RO membrane apparatus equipped with SEOFs allowed comparison of UV-A (photocatalysis-enabled) versus UV-C (direct photolysis disinfection). Compared against systems without any light exposure, systems with UV-C light formed thinner-but denser-biofilms, prevented permeate flux declines due to biofouling, and maintained the highest salt rejection. Results were corroborated by in-situ optical coherence tomography and ex-situ measurements of biofilm growth on the membranes. Transcriptomic analysis showed that UV-C SEOFs down-regulated quorum sensing and surface attachment genes. In contrast, UV-A SEOFs upregulated quorum sensing, surface attachment, and oxidative stress genes, resulting in higher extracellular polymeric substances (EPS) accumulation on membrane surfaces. Overall, SEOFs that deliver a low fluence of UV-C light onto membrane surfaces are a promising non-chemical approach for mitigating biofouling formation on RO membranes.

Simultaneous removal of heavy metals and dyes in water using a MgO-coated Fe3O4 nanocomposite: Role of micro-mixing effect induced by bubble generation.

This study focused on the development of a nano-adsorbent for contaminant removal without the use of any external energy. An eco-friendly Fe3O4@MgO core-shell nanocomposite was synthesized and tested for the removal of a heavy metal, lead (Pb2+) and a dye, rhodamine B (RhB). The addition of H2O2 into the system enabled the self-mixing of the aqueous solution containing Fe3O4@MgO through the generation of bubbles. This system showed an excellent removal efficiency of 99% in just 15 min for Pb2+ and 120 min for RhB, which is far better than the control experiment (without H2O2). The cation exchange mechanism dominated in the removal of heavy metals, while the adsorptive removal of dye proceeded through the H-bonding between Mg(OH)2 and dye molecules. The removal efficiency increased exponentially with the increase of H2O2 at the optimal concentration of 5% and it was effective over a wide pH range. Moreover, the performance of the Fe3O4@MgO-H2O2 system was verified for other heavy metals such as Cd, Ni, Zn, Co, and Cu, demonstrating that the Fe3O4@MgO-H2O2 system can be widely implemented in the treatment of real water matrices contaminated with heavy metals and organic dyes.

Unified Metallic Catalyst Aging Strategy and Implications for Water Treatment.

Heterogeneous catalysis holds great promise for oxidizing or reducing a range of pollutants in water. A well-recognized, but understudied, barrier to implement catalytic treatment centers around fouling or aging over time of the catalyst surfaces. To better understand how to study catalyst fouling or aging, we selected a representative bimetallic catalyst (Pd-In supported on Al2O3), which holds promise to reduce nitrate to innocuous nitrogen gas byproducts upon hydrogen addition, and six model solutions (deionized water, sodium hypochlorite, sodium borohydride, acetic acid, sodium sulfide, and tap water). Our novel aging experimental apparatus permitted single passage of each model solution, separately, through a small packed-bed reactor containing replicate bimetallic catalyst "beds" that could be sacrificed weekly for off-line characterization to quantify impacts of fouling or aging. The composition of the model solutions led to the following gradual changes in surface composition, morphology, or catalytic reactivity: (i) formation of passivating species, (ii) decreased catalytic sites due to metal leaching under acid conditions or sulfide poisoning, (iii) dissolution and/or transformation of indium, (iv) formation of new catalytic sites by the introduction of an additional metallic element, and (v) oxidative etching. The model solution water chemistry captured a wide range of conditions likely to be encountered in potable or industrial water treatment. Aging-induced changes altered catalytic activity and provided insights into potential strategies to improve long-term catalyst operations for water treatment.

Dimensionally Stable Anode Based Sensor for Urea Determination via Linear Sweep Voltammetry.

Urea is an added value chemical with wide applications in the industry and agriculture. The release of urea waste to the environment affects ecosystem health despite its low toxicity. Online monitoring of urea for industrial applications and environmental health is an unaddressed challenge. Electroanalytical techniques can be a smart integrated solution for online monitoring if sensors can overcome the major barrier associated with long-term stability. Mixed metal oxides have shown excellent stability in environmental conditions with long lasting operational lives. However, these materials have been barely explored for sensing applications. This work presents a proof of concept that demonstrates the applicability of an indirect electroanalytical quantification method of urea. The use of Ti/RuO2-TiO2-SnO2 dimensional stable anode (DSA®) can provide accurate and sensitive quantification of urea in aqueous samples exploiting the excellent catalytic properties of DSA® on the electrogeneration of active chlorine species. The cathodic reduction of accumulated HClO/ClO- from anodic electrogeneration presented a direct relationship with urea concentration. This novel method can allow urea quantification with a competitive LOD of 1.83 × 10-6 mol L-1 within a linear range of 6.66 × 10-6 to 3.33 × 10-4 mol L-1 of urea concentration.

Carbon-nitride-based micromotor driven by chromate-hydrogen peroxide redox system: Application for removal of sulfamethaxazole.

In this study, a Janus Fe/C3N4 micromotor driven by a chromate-hydrogen peroxide (Cr(VI)/H2O2) redox system was developed and its movement was analyzed. The motion of the micromotor was tracked via nanoparticle tracking analysis (NTA) and the corresponding diffusion coefficients (D) were determined. The NTA results revealed that D = 0 in water in the absence of additives (Cr(VI) or H2O2). The addition of H2O2 resulted in an increase in D from 0 to 12 × 106 nm2 s-1, which further increased to 20 × 106, 26.5 × 106, 29 × 106, and 44 × 106 nm2 s-1 with the addition of 0.5, 1, 2, and 5 ppm of Cr(VI), respectively. Cr(VI) alone did not efficiently propel the Fe/C3N4-based micromotor. Therefore, it was proposed that the Cr(VI)/H2O2 redox system generates O2, which plays a major role in the movement of the C3N4-based micromotor. In addition, the formation of reactive species, such as OH and 1O2, was confirmed through electron spin resonance experiments. The reactive species efficiently degraded sulfamethaxazole (SMX), an organic pollutant, as demonstrated through degradation studies and product analyses. The effects of various parameters, such as H2O2 concentration, Cr(VI) concentration, and initial pH on the movement of micromotor and degradation of SMX were also documented.

In situ chemical oxidation of contaminated groundwater using a sulfidized nanoscale zerovalent iron-persulfate system: Insights from a box-type study.

We report the potential of a sulfidized nanoscale zerovalent iron-persulfate (S-nZVI-PS) system for in situ chemical oxidation (ISCO) of groundwater pollutants. The study was conducted using a sand-filled rectangular box with a permeable reactive barrier of S-nZVI as a facsimile of the ISCO system. Synthetic water contaminated with a target pollutant (reactive black-5, RB-5) was continuously passed through the box. The injection of PS led to the complete removal of RB-5 and the system remained reactive for approximately 12 days. This system has a benefit that the oxidation products of S-nZVI (i.e., Fe3O4, Fe2O3, and FeSO4) can further activate PS to retain its reactivity. In a separate trial, this method exploited oxidation, reduction, adsorption and co-precipitation mechanisms that conspired to remove two different groundwater pollutants- arsenite and 1,4-dioxane. These results confirmed the utility of S-nZVI-PS as a mediator of ISCO processes to degrade groundwater pollutants.

Surveillance Rate and its Impact on Survival of Hepatocellular Carcinoma Patients in South Korea: A Cohort Study.

PURPOSE: Though regular surveillance of hepatocellular carcinoma (HCC) for high-risk patients is widely recommended, its rate and effectiveness are not clear. The aim of this study is to investigate the actual rate of HCC surveillance and its related factors and to clarify its impact on survival in a Korean HCC cohort. MATERIALS AND METHODS: From 2012 to 2015, 319 newly diagnosed HCC patients were prospectively enrolled at a tertiary hospital. Patient interviews based on a structured questionnaire survey were conducted. Surveillance was defined as liver imaging test ≥ 2 times with at least 3-month interval within 2 years prior to HCC diagnosis. RESULTS: Surveillance rate was 39.8%. Of the HCC patients with high-risk factors, only 182 (57.1%) had knowledge for the need for regular surveillance, and 141 (44.2%) had the accurate information about the method (ultrasound-based study). Surveillance group showed a higher proportion of early HCC (p < 0.001) and a longer overall survival (p < 0.001) compared to non-surveillance group. The multivariable Cox regression analysis indicated Child-Pugh class A, history of anti-viral therapy, low serum α-fetoprotein level, non-advanced Barcelona Clinic Liver Cancer stage as independent predictors of overall survival, while regular surveillance was not (p=0.436). CONCLUSION: Less than half of the newly diagnosed Korean HCC patients were under surveillance and the accurate perception for the need of HCC surveillance was insufficient. Of those under surveillance, most patients were diagnosed with early stage HCC, which led to the improved survival. Comprehensive efforts to optimize the surveillance program for the target population are warranted.

Liver volume index predicts the risk of esophageal variceal hemorrhage in cirrhotic patients on propranolol prophylaxis.

BACKGROUND/AIMS: Non-selective ß-blockers (NSBBs) are used for primary prevention of esophageal variceal hemorrhage (VH) in patients with portal hypertension, but a significant number of patients develop VH while on NSBB therapy. In this study, we sought to determine whether liver volume can predict the risk of primary prophylaxis failure in cirrhotic patients on NSBB therapy. METHODS: A retrospective cohort of 309 patients on prophylactic propranolol was analyzed. Liver volume was measured in portal venous phase images of multidetector computed tomography. Predictors of VH were assessed using a Cox proportional hazards model with competing-risks analysis. A nomogram was developed for estimation of the risk of primary prophylaxis failure. RESULTS: During a median follow-up of 36 months, 37 patients on propranolol developed VH. Liver volume index, the ratio of measured-to-expected liver volume, was an independent predictor of VH (adjusted hazard ratio [HR], 2.70; 95% confidence interval [CI], 1.37 to 5.33; p = 0.004) as were the presence of large varices and the absence of ascites. A nomogram-based volume score of > 0.6 was predictive of prophylaxis failure (HR, 7.54; 95% CI, 2.88 to 19.73; p < 0.001). Time-dependent receiver operating characteristic curve analysis revealed that a nomogram-based risk score had significantly better discriminatory power than the North Italian Endoscopy Club index in predicting prophylaxis failure at 6 and 8 years. CONCLUSION: Liver volume index is an independent predictor of first VH and a nomogram-based volume score stratifies the VH risk in cirrhotic patients on propranolol prophylaxis.

Advanced oxidation and adsorptive bubble separation of dyes using MnO2-coated Fe3O4 nanocomposite.

In this study, MnO2-coated Fe3O4 nanocomposite (Fe3O4@MnO2) was utilized to decompose H2O2 to remove dyes via advanced oxidation processes and adsorptive bubble separation (advanced ABS system). The combination of H2O2 and Fe3O4@MnO2 generated bubbles and formed a stable foam layer in the presence of a surfactant; sodium dodecyl sulfate (SDS) or cetyltrimethylammonium chloride (CTAC), separating dye from the solution. On the basis of radical quenching experiments, electron paramagnetic resonance and X-ray photoelectron spectroscopy analyses, it was confirmed that the MnO2 shell of catalyst was reduced to Mn2O3 by H2O2, generating radicals and oxygen gas for the removal of dyes. In the advanced ABS system, ∙OH and 1O2 were the main radical species and the O2 concentrations of 0.34 and 0.71 mM were increased in the solution and headspace, respectively. The advanced ABS system demonstrated a high removal efficiency of methylene blue (MB) (99.0%) and the removal rate increased with increasing amounts of components (H2O2, catalyst and SDS). Also, the advanced ABS system maintained high removal efficiency of MB at a wide pH range of 3-9. In addition to the anionic surfactant of SDS, CTAC was applied as a cationic surfactant for the advanced ABS of anionic dyes. Lastly, the scale-up system was applied to remediate dye-contaminated river water and industrial wastewater for possible practical applications.

Liver volume-based prediction model stratifies risks for hepatocellular carcinoma in chronic hepatitis B patients on surveillance.

BACKGROUND AND AIM: The aim of this study was to determine whether dynamic computed tomography (CT)-measured liver volume predicts the risk of hepatocellular carcinoma (HCC) when the CT scans do not reveal evidence of HCC in chronic hepatitis B (CHB) patients on surveillance. METHODS: This retrospective multicentre cohort study included 1,246 patients who received entecavir and regular HCC surveillance in three tertiary referral centres in South Korea. Liver volumes were measured on portal venous phase CT images. A nomogram was developed based on Cox independent predictors and externally validated. Time-dependent receiver operating characteristic (ROC) analysis was performed for comparison with previous prediction models. RESULTS: Patients who received dynamic CT studies during surveillance had significantly higher risk for HCC compared to patients without CT studies (hazard ratio [HR] = 3.1; p < 0.001). Expected/measured liver volume ratio was an independent predictor of HCC (HR = 4.2; p = 0.002) in addition to age, sex and cirrhosis. The nomogram based on the four predictors discriminated risks for HCC (HR = 4.1 and 6.0 in derivation and validation cohort, respectively, for volume score > 150; p < 0.001). Time-dependent ROC analysis confirmed better performance of the volume score compared to HCC prediction models with conventional predictors (integrated area under curve = 0.758 vs. 0.661-0.712; p < 0.05). CONCLUSIONS: CT-measured liver volume is an independent predictor of future HCC, and nomogram-based liver volume score may stratify the risks of HCC in CHB patients who showed negative CT findings for HCC during surveillance.

Self-Generation of Reactive Oxygen Species on Crystalline AgBiO3 for the Oxidative Remediation of Organic Pollutants.

In this study, we synthesized a novel perovskite nanomaterial consisting of AgBiO3 nanoparticles (NPs) via an ion-exchange method for remediation of polluted environments. The AgBiO3 NPs could self-produce significant amounts of reactive oxygen species (ROS) without light illumination or any other additional oxidant due to the controllable release of lattice oxygen from the crystalline AgBiO3, resulting in the formation of ROS somehow. The self-produced 1O2, O2•-, and •OH were confirmed by electron spin resonance spectroscopy using a spin trap technique. We found that the AgBiO3 NPs could be reused for the mineraliztion of most recalcitrant organic compounds alone, including Rhodamine B (RhB), phenol, 4-chlorophenol, 2,4-dichlorophenol, and bisphenol A. After the repeated eight cycles of continious treatment of RhB, AgBiO3 NPs still achieved 79% of degradation after 30 min of treatment. Characterization results revealved that the lattice oxygen inside AgBiO3 was activated to form active oxygen (O*), which resulted in consecutive formation of ROS. This study provides new insight on the lattice oxygen activation mechanism of silver bismuthate and its application to the remediation of polluted waters.

Optimizing Surveillance Performance of Alpha-Fetoprotein by Selection of Proper Target Population in Chronic Hepatitis B.

Although alpha-fetoprotein (AFP) is the most widely used biomarker in hepatocellular carcinoma (HCC) surveillance, disease activity may also increase AFP levels in chronic hepatitis B (CHB). Since nucleos(t)ide analog (NA) therapy may reduce not only HBV viral loads and transaminase levels but also the falsely elevated AFP levels in CHB, we tried to determine whether exposure to NA therapy influences AFP performance and whether selective application can optimize the performance of AFP testing in CHB during HCC surveillance. A retrospective cohort of 6,453 CHB patients who received HCC surveillance was constructed from the electronic clinical data warehouse. Covariates of AFP elevation were determined from 53,137 AFP measurements, and covariate-specific receiver operating characteristics regression analysis revealed that albumin levels and exposure to NA therapy were independent determinants of AFP performance. C statistics were largest in patients with albumin levels ≥ 3.7 g/dL who were followed without NA therapy during study period, whereas AFP performance was poorest when tested in patients with NA therapy during study and albumin levels were < 3.7 g/dL (difference in C statics = 0.35, p < 0.0001). Contrary to expectation, CHB patients with current or recent exposure to NA therapy showed poorer performance of AFP during HCC surveillance. Combination of concomitant albumin levels and status of NA therapy can identify subgroup of CHB patients who will show optimized AFP performance.

Degradation of synthetic pollutants in real wastewater using laccase encapsulated in core-shell magnetic copper alginate beads.

Immobilization of laccase has been highlighted to enhance their stability and reusability in bioremediation. In this study, we provide a novel immobilization technique that is very suitable to real wastewater treatment. A perfect core-shell system composing copper alginate for the immobilization of laccase (Lac-beads) was produced. Additionally, nFe2O3 was incorporated for the bead recycling through magnetic force. The beads were proven to immobilize 85.5% of total laccase treated and also to be structurally stable in water, acetate buffer, and real wastewater. To test the Lac-beads reactivity, triclosan (TCS) and Remazol Brilliant Blue R (RBBR) were employed. The Lac-beads showed a high percentage of TCS removal (89.6%) after 8h and RBBR decolonization at a range from 54.2% to 75.8% after 4h. Remarkably, the pollutants removal efficacy of the Lac-beads was significantly maintained in real wastewater with the bead recyclability, whereas that of the corresponding free laccase was severely deteriorated.

Enhancing the reactivity of bimetallic Bi/Fe(0) by citric acid for remediation of polluted water.

In this study, the environmentally benign citric acid (CA) was utilized to improve the aerobic degradation of 4-chlorophenol (4-CP) over bismuth modified nanoscale zero-valent iron (Bi/Fe(0)). The characterization results revealed the existence of bismuth covering on the Fe(0) surface under zero-valent state. And, the Bi/Fe(0)-CA+O2 system performed excellent reactivity in degradation of 4-CP due to the generation of reactive oxygen species (ROS), which was confirmed by electron spin resonance (ESR) spectroscopy. After 30min of reaction, 80% of 4-CP was removed using Bi/Fe(0)-CA+O2 accompanying with high dechlorination rate. The oxidative degradation intermediates were analyzed by HPLC and LC-MS. We found that CA could promote the bismuth-iron system to produce much reactive oxygen species ROS under both aerobic and anaerobic conditions due to its ligand function, which could react with Fe(3+) to form a ligand complex (Fe(III)Cit), accompanying with a considerable production of Fe(2+) and H2O2. This study provides a new strategy for generating ROS on nZVI and suggests its application for the mineralization of many recalcitrant pollutants.

Analysis of Plaque Composition in Coronary Chronic Total Occlusion Lesion Using Virtual Histology-Intravascular Ultrasound.

BACKGROUND AND OBJECTIVES: Success rates of chronic total occlusion (CTO) percutaneous coronary intervention (PCI) have recently been reported to range from 80% to 90%. A better understanding of the pathologic characteristics of the CTO lesion may helpful to improving CTO PCI success rates. We evaluated the CTO lesion in patients with stable angina (SA) by virtual histology-intravascular ultrasound (VH-IVUS). SUBJECTS AND METHODS: The study population consisted of 149 consecutive patients with SA underwent VH-IVUS examination. We analyzed demographic and VH-IVUS findings in 22 CTO patients (17 males; mean, 62.3 years old) compared with 127 non-CTO patients (82 males; mean, 61.3 years old). RESULTS: A significantly lower ejection fraction (57.6±13.0% vs. 65.4±8.8%, p=0.007) was detected in the CTO group compared with the non-CTO group. Reference vessel lumen area of the proximal and distal segment was significantly less in CTO group than in non-CTO group. The lesion length of the CTO group was significantly longer than those of the non-CTO group (24.4±9.6 mm vs. 17.2±7.4 mm, p<0.001). Total atheroma volume (224±159 mm(3) vs. 143±86 mm(3), p=0.006) and percent atheroma volume (63.2±9.6% vs. 55.8±8.5%, p=0.011) of the CTO group were also significantly greater than those of non-CTO group. However, the lesion length adjusted plaque composition of the CTO group was not significantly different compared with that of the non-CTO group. CONCLUSION: CTO lesions had a longer lesion length and greater plaque burden than the non-CTO lesion in patients with SA. However, lesion length adjusted plaque composition showed similar between the two groups. These results support that plaque characteristics of CTO lesions are similar to non-CTO lesions in patients with SA.

Novel self-assembled bimetallic structure of Bi/Fe(0): the oxidative and reductive degradation of hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX).

A novel self-assembled bimetallic zero-valent bismuth/iron (Bi/Fe(0)) composite was synthesized, characterized, and used successfully to remove hexahydro-1,3,5-trinitro-1,3,5-triazine (RDX) from wastewater. To assess the oxidative and reductive reactivities of Bi/Fe(0) nanoparticles (NPs), RDX degradation experiments were conducted in either ambient or anaerobic conditions, respectively. The best RDX degradation was achieved using 4%-Bi/Fe(0) (atomic ratio) NPs. In ambient conditions, concentrations of Fe(2+) ions and H2O2 were lower in the Bi/Fe(0) solution than in the Fe(0) solution; this difference indicates that most Fe(2+) ions and H2O2 reacted to produce hydroxyl radicals (*OH) and superoxide radical anions (O2(*-)), thereby resulting in the remarkable degradation of RDX. In anaerobic conditions, the presence of Bi increased the electron generation rate from the surfaces of the Bi/Fe(0) NPs. This increase was responsible for the excellent reductive degradation of RDX. Based on Density Functional Theory (DFT) calculations, the adsorption of water was endothermic on Fe(0) NPs and exothermic on Bi/Fe(0) NPs. Therefore, only the dissociation reactions of H2O in the Bi/Fe(0) system were spontaneous, and these reactions resulted in the prominent reactivity of the Bi/Fe(0) NPs.

Fabrication of novel oxygen-releasing alginate beads as an efficient oxygen carrier for the enhancement of aerobic bioremediation of 1,4-dioxane contaminated groundwater.

Oxygen-releasing alginate beads (ORABs), a new concept of oxygen-releasing compounds (ORCs) designed to overcome some limitations regarding the fast oxygen release rate and the high pH equilibrium of ORCs, were fabricated to promote the stimulation of aerobic biodegradation in anaerobic groundwater. Slow oxygen-releasing rate and maintenance of constant pH were achieved by changing the parameters (ionic radius and valence) related to the cross-linking ions composing ORABs, and the best results were obtained for ORABs cross-linked with Al (Al-ORABs). Furthermore, the mechanism of the improved aerobic biodegradation using Al-ORABs under oxygen-limiting groundwater conditions was elucidated in batch and column studies with 1,4-dioxane and Mycrobacterium sp. PH-06 as a model contaminant and aerobic microbes, respectively. Maximum 1,4-dioxane degradations of 99% and 68.1% were achieved when Al-ORABs were applied in batch and column conditions, respectively, whereas 34.3% and 18% of 1,4-dioxane were degraded without Al-ORABs in batch and column conditions, respectively.

A novel self-assembling nanoparticle of Ag-Bi with high reactive efficiency.

A novel Ag-Bi nanoparticle has been prepared via a facile precipitation approach. The nanoparticle could achieve purification of contaminated water without supplements and exhibited much higher activity compared to other popular nanoparticles (e.g. nZVI). The excellent performance of Ag-Bi was due in part to a large production of ˙OH radicals.