Health economic analysis and medical cost analysis of children with severe hepatitis B in China: A retrospective study from 2016 to 2022.

BACKGROUND: Hepatitis B poses a heavy burden for children in China, however, the national studies on the distributional characteristics and health care costs of children with severe hepatitis B is still lacking. This study aimed to analyze the disease characteristics, health economic effects, and medical cost for children with severe hepatitis B in China. METHODS: Based on patient information in the Hospital Quality Monitoring System, cases with severe hepatitis B were divided into four groups according to age, and the etiology and symptoms of each group were quantified. The cost of hospitalization was calculated for cases with different disease processes, and severity of disease. The spatial aggregation of cases and the relationship with health economic factors were analyzed by Moran's I  analysis. RESULTS: The total number of children discharged with hepatitis B from January 2016 to April 2022 was 1603, with an average age of 10.5 years. Liver failure cases accounted for 43.48% (697/1603,) of total cases and cirrhosis cases accounted for 11.23% (180/1603,). According to the grouping of disease progression, there were 1292 cases without associated complications, and the median hospitalization cost was $818.12. According to the spatial analysis, the aggregation of cases was statistically significant at the prefectural and provincial levels in 2019, 2020, and 2021 (all P <0.05). The number of severe cases was negatively correlated with gross domestic product (GDP, Moran's I <0) and percentage of urban population (Moran's I <0), and positively correlated with the number of pediatric beds per million population (Moran's I >0). CONCLUSION: The number of severe hepatitis B cases is low in areas with high GDP levels and high urban population ratios, and health care costs have been declining over the years.

Multidimensional dynamic prediction model for hospitalized patients with the omicron variant in China.

Purpose: To establish dynamic prediction models by machine learning using daily multidimensional data for coronavirus disease 2019 (COVID-19) patients. Methods: Hospitalized COVID-19 patients at Peking Union Medical College Hospital from Nov 2nd, 2022, to Jan 13th, 2023, were enrolled in this study. The outcome was defined as deterioration or recovery of the patient's condition. Demographics, comorbidities, laboratory test results, vital signs, and treatments were used to train the model. To predict the following days, a separate XGBoost model was trained and validated. The Shapley additive explanations method was used to analyze feature importance. Results: A total of 995 patients were enrolled, generating 7228 and 3170 observations for each prediction model. In the deterioration prediction model, the minimum area under the receiver operating characteristic curve (AUROC) for the following 7 days was 0.786 (95% CI 0.721-0.851), while the AUROC on the next day was 0.872 (0.831-0.913). In the recovery prediction model, the minimum AUROC for the following 3 days was 0.675 (0.583-0.767), while the AUROC on the next day was 0.823 (0.770-0.876). The top 5 features for deterioration prediction on the 7th day were disease course, length of hospital stay, hypertension, and diastolic blood pressure. Those for recovery prediction on the 3rd day were age, D-dimer levels, disease course, creatinine levels and corticosteroid therapy. Conclusion: The models could accurately predict the dynamics of Omicron patients' conditions using daily multidimensional variables, revealing important features including comorbidities (e.g., hyperlipidemia), age, disease course, vital signs, D-dimer levels, corticosteroid therapy and oxygen therapy.

Evaluation of ICUs and weight of quality control indicators: an exploratory study based on Chinese ICU quality data from 2015 to 2020.

This study aimed to explore key quality control factors that affected the prognosis of intensive care unit (ICU) patients in Chinese mainland over six years (2015-2020). The data for this study were from 31 provincial and municipal hospitals (3425 hospital ICUs) and included 2 110 685 ICU patients, for a total of 27 607 376 ICU hospitalization days. We found that 15 initially established quality control indicators were good predictors of patient prognosis, including percentage of ICU patients out of all inpatients (%), percentage of ICU bed occupancy of total inpatient bed occupancy (%), percentage of all ICU inpatients with an APACHE II score ⩾15 (%), three-hour (surviving sepsis campaign) SSC bundle compliance (%), six-hour SSC bundle compliance (%), rate of microbe detection before antibiotics (%), percentage of drug deep venous thrombosis (DVT) prophylaxis (%), percentage of unplanned endotracheal extubations (%), percentage of patients reintubated within 48 hours (%), unplanned transfers to the ICU (%), 48-h ICU readmission rate (%), ventilator associated pneumonia (VAP) (per 1000 ventilator days), catheter related blood stream infection (CRBSI) (per 1000 catheter days), catheter-associated urinary tract infections (CAUTI) (per 1000 catheter days), in-hospital mortality (%). When exploratory factor analysis was applied, the 15 indicators were divided into 6 core elements that varied in weight regarding quality evaluation: nosocomial infection management (21.35%), compliance with the Surviving Sepsis Campaign guidelines (17.97%), ICU resources (17.46%), airway management (15.53%), prevention of deep-vein thrombosis (14.07%), and severity of patient condition (13.61%). Based on the different weights of the core elements associated with the 15 indicators, we developed an integrated quality scoring system defined as F score=21.35%xnosocomial infection management + 17.97%xcompliance with SSC guidelines + 17.46%×ICU resources + 15.53%×airway management + 14.07%×DVT prevention + 13.61%×severity of patient condition. This evidence-based quality scoring system will help in assessing the key elements of quality management and establish a foundation for further optimization of the quality control indicator system.

Effect of ICU quality control indicators on VAP incidence rate and mortality: a retrospective study of 1267 hospitals in China.

PURPOSE: To investigate the effects of ICU quality control indicators on the VAP incidence rate and mortality in China throughout 2019. METHODS: This was a retrospective study. A total of 1267 ICUs from 30 provinces in mainland China were included. Data were collected using the National Clinical Improvement System Data that report ICU information. Ten related quality control indicators were analyzed, including 5 structural factors (patient-to-bed ratio, physician-to-bed ratio, nurse-to-bed ratio, patient-to-physician ratio, and patient-to-nurse ratio), 3 process factors (unplanned endotracheal extubation rate, reintubation rate within 48 h, and microbiology detection rate before antibiotic use), and 2 outcome factors (VAP incidence rate and mortality). The information on the most common infectious pathogens and the most commonly used antibiotics in ICU was also collected. The Poisson regression model was used to identify the impact of factors on the incidence rate and mortality of VAP. RESULTS: The incidence rate of VAP in these hospitals in 2019 was 5.03 (2.38, 10.25) per 1000 ventilator days, and the mortality of VAP was 11.11 (0.32, 26.00) %. The most common causative pathogen was Acinetobacter baumannii (in 39.98% of hospitals), followed by Klebsiella pneumoniae (38.26%), Pseudomonas aeruginosa, and Escherichia coli. In 26.90% of hospitals, third-generation cephalosporin was the most used antibiotic, followed by carbapenem (24.22%), penicillin and beta-lactamase inhibitor combination (20.09%), cephalosporin with beta-lactamase inhibitor (17.93%). All the structural factors were significantly associated with VAP incidence rate, but not with the mortality, although the trend was inconsistent. Process factors including unplanned endotracheal extubation rate, reintubation rate in 48 h, and microbiology detection rate before antibiotic use were associated with higher VAP mortality, while unplanned endotracheal extubation rate and reintubation rate in 48 h were associated with higher VAP mortality. Furthermore, K. pneumoniae as the most common pathogen was associated with higher VAP mortality, and carbapenems as the most used antibiotics were associated with lower VAP mortality. CONCLUSION: This study highlights the association between the ICU quality control (QC) factors and VAP incidence rate and mortality. The process factors rather than the structural factors need to be further improved for the QC of VAP in the ICU.

Online taxi users' optimistic bias: China youths' digital travel and information privacy protection.

Digital travel platforms not only provided people with convenient travel but also raised a series of problems regarding information privacy protection. In order to analyze privacy protection behavior, this study surveyed 441 subjects aged 18-35 who utilized digital travel platforms based on a structural model of protective motivation theory. The results indicated that a perceived threat, self-efficacy, and response efficacy positively and significantly impacted youths' privacy concerns. Furthermore, privacy concerns were positively related to privacy protection behavior and were an intermediate variable between the relationships among perceived threat, self-efficacy, response efficacy, and privacy protection behavior. This study identified the moderating effect of youths' knowledge of platform privacy settings on the relationship between privacy concerns and protection behavior. In addition, the results confirmed that an optimistic bias did exist among talented youth with high privacy knowledge in terms of a practical level of privacy management. These unique findings represent the exceptional contributions and innovation points of this study.

Molybdenum disulfide-graphene oxide composites as dispersive solid-phase extraction adsorbents for the enrichment of four paraben preservatives in cosmetics.

Molybdenum disulfide-graphene oxide composite (MoS2/GO) was synthesized and used as the adsorbent in dispersive solid-phase extraction. Four paraben preservatives, namely, methylparaben, ethylparaben, propylparaben, and butylparaben, were enriched with MoS2/GO and determined by ultra-high-performance liquid chromatography. Molybdenum disulfide was intercalated into graphene oxide layers to reduce self-aggregation by using the solvothermal method. The experimental results indicated that the as-prepared MoS2/GO composite exhibited great enrichment capability toward those four paraben preservatives, and the adsorption time was 10 min and the elution time was as short as 1 min. The mechanism of MoS2/GO composite and parabens is attributed to hydrogen bonding and electrostatic attraction. The relative standard deviation (RSD, n = 9) of this method was below 7.6%. Limits of detection and limits of quantification were in the range 0.4-2.3 ng/mL and 1.4-7.6 ng/mL, respectively. The recoveries obtained from the parabens of cosmetic sample were in the range 91.3-124% with RSDs below 10%. The developed method has great potential for the determination of emerging contaminants with low cost and high sensitivity.

A novel lanthanum-modified copper tailings adsorbent for phosphate removal from water.

La(OH)3-modified copper tailings were prepared, characterized, and investigated for phosphate removal from water in this study. Scanning electron microscopy (SEM) analysis showed that La(OH)3 modification made a large amount of spherical solid agglomerates appeared on the surface of the copper tailings and created many pores. Laser particle size analysis indicated that the modified copper tailings had much a smaller particle size and larger specific surface area. Fourier Transform Infrared Spectroscopy (FTIR) and X-ray fluorescence (XRF) analysis illustrated that lanthanun was successfully loaded on the copper tailings with a mass percentage of 25.31%. The adsorption kinetics and isothermal adsorption experiment results indicated that the La(OH)3-modified copper tailings had a much better phosphate adsorption capacity than the original copper tailings. The adsorption kinetics process of the La(OH)3-modified copper tailings followed the pseudo-second-order kinetic model, and the isothermal adsorption data were well fitted by the Langmuir isotherm model. The maximum phosphorus adsorption capacity of the copper tailings after alkali treatment and La(OH)3 modification increased from 737.04 mg/kg to 7078.43 mg/kg, which was close to that of Phoslock. Leaching toxicity testing demonstrated that the use of La(OH)3-modified copper tailings for phosphorus removal in water treatment would not cause secondary pollution. Adsorption mechanism analysis revealed that both electrostatic attraction and ligand exchange were involved in phosphate adsorption onto La(OH)3-modified copper tailings. The phosphate adsorption of La(OH)3-modified copper tailings was pH-dependent, and a high-pH environment resulted in a decline in adsorption capacity. The increased concentration of OH- in high-pH solution was unfavorable for ligand exchange between phosphate species and hydroxyl groups from La(OH)2 species. In addition, competitive adsorption between HPO42- and the increased amounts of OH- weakened electrostatic attraction. The results suggested that La(OH)3-modified copper tailings are promising adsorbents for highly efficient phosphate removal and provide a new method to realize the resource utilization of copper tailings.

Development of a highly efficient electrochemical flow-through anode based on inner in-site enhanced TiO2-nanotubes array.

This paper reports on the development of macroporous flow-through anodes. The anodes comprised an enhanced TiO2 nanotube array (ENTA) that was grown on three macroporous titanium substrates (MP-Ti) with nominal pore sizes of 10, 20, and 50 µm. The ENTA was then covered with SnO2-Sb2O3. We refer to this anode as the MP-Ti-ENTA/SnO2-Sb2O3 anode. The morphology, pore structure, and electrochemical properties of the anode were characterized. Compared with the traditional NTA layer, we found that the MP-Ti-ENTA/SnO2-Sb2O3 anode has a service lifetime that was 1.56 times larger than that of MP-Ti-NTA/SnO2-Sb2O3. We used 2-methyl-4-isothiazolin-3-one (MIT), a common biocide, as the target pollutant. We evaluated the impact of the operating parameters on energy efficiency and the oxidation rate of MIT. Furthermore, the apparent rate constants were 0.38, 1.63, and 1.24 min-1 for the 10, 20, and 50 µm nominal pore sizes of the MP-Ti substrates, respectively, demonstrating the different coating-loading mechanisms for the porous substrate. We found that hydroxyl radicals were the dominant species in the MIT oxidation in the HO radical scavenging experiments. The radical and nonradical oxidation contributions to the MIT degradation for different current densities were quantitatively determined as 72.1%-74.8% and 25.2%-27.9%, respectively. Finally, we summarized the oxidation performance for MIT destruction for (1) the published literature on various advanced oxidation technologies, (2) the published literature on various anodes, and (3) our flow-by and -through anodes. Accordingly, we found that our flow-through anode has a much lower electrical efficiency per order value (0.58 kWh m-3) than the flow-by anodes (6.85 kWh m-3).

Degradation kinetics of target compounds and correlations with spectral indices during UV/H2O2 post-treatment of biologically treated acrylonitrile wastewater.

In this study, the post-treatment of biologically treated acrylonitrile wastewater was investigated during UV/H2O2 process. Five contaminants in the effluent were selected as target compounds, including Furmaronitrile (FMN), 3-Pyridinecarbonitrile (3PCN), 1,3-Dicyanobenzene (1,3-DCB), 5-Methyl-1H-benzotriazole (5MBT), and 7-Azaindole (7AID). Under optimal reaction conditions, the UV/H2O2 post-treatment exhibited good performances in destruction of organic compounds and toxicity. The photo-chemical parameters of the target compounds were measured and it was found that 5MBT and 3PCN had fast degradation rate constants under direct UV photolysis. The second-order rate constants of the target compounds with hydroxyl radicals were determined to be in the range of (1.0-5.0) × 109 M-1 s-1 at pH 3.0 and 25 °C. A simplified pseudo-first-order steady state (Sim-PSS) model, which considered direct UV photolysis and radical oxidation simultaneously, agreed well with the experimental data from the post-treatment of a biologically treated effluent. High-performance size exclusion chromatography (HPSEC) coupled with diode-array detector (DAD) and fluorescence detector (FLD) analysis revealed that humic-like sub-peak signals from different molecular weights of fluorescent organic matter decreased consistently during the oxidation process, which made humic-like fluorescence exhibit higher correlation with the target compounds' degradation than the spectral indices of UV absorbance at 254 nm (UVA254) and protein-like fluorescence.

Development of a Three-Dimensional Electrochemical System Using a Blue TiO2/SnO2-Sb2O3 Anode for Treating Low-Ionic-Strength Wastewater.

Reducing energy use is crucial to commercialize electrochemical oxidation technologies. We developed a three-dimensional (3-D) electrochemical system that can significantly reduce the applied voltage and effectively degrade organic contaminants in low-ionic-strength wastewaters. The 3-D system consisted of a composite wire mesh anode (composed of blue TiO2 nanotubes covered with SnO2-Sb2O3), a proton exchange membrane, and a stainless-steel wire mesh cathode, which were compressed firmly together. For the 3-D system, we placed the anode of a 3-D electrode toward the wastewater that flowed past the anode. Both the two-dimensional (2-D) and 3-D systems had the same anode and cathode. We found that the 3-D system could reduce the applied voltage by 75.7% and reduce the electrical efficiency per log order reduction (EE/O) by 73% for 0.001 M Na2SO4. For Na2SO4 concentrations greater than 0.05 M, the 2-D system had a slightly lower EE/O. We also compared the EE/O of electrochemical advanced oxidation processes (EAOPs) with that of other advanced oxidation processes (UV/H2O2, UV/persulfate, O3/H2O2, UV/ TiO2, and UV/chlorine). We found that EAOPs have a much higher EE/O for low BA concentrations (20 mg/L) and a much lower EE/O for high BA concentrations (2000 mg/L).

Electrochemical degradation of ciprofloxacin on BDD anode using a differential column batch reactor: mechanisms, kinetics and pathways.

A growing number of electrochemical oxidation system was employed for the degradation of refractory contaminants. In this study, a boron-doped diamond (BDD) anode/Ti cathode equipped in the differential column batch reactor (DCBR) was utilized for electrochemical oxidation of ciprofloxacin (CIP). The feed solution within the DCBR system was confirmed as a uniform flow state through a computational fluid dynamics (CFD) simulation analysis. The results showed that the BDD anode/Ti cathode electrochemical system was with a high efficiency oxidation performance when treating the CIP contaminant. The CIP was completely degraded within 20 min, and over 50% DOC removed after 120 min. Therefore, two-stage electrochemical oxidation mechanism was proposed. Four major factors, the initial concentration, current density, pH, and electrolyte concentration, on the CIP degradation efficiency were systematically investigated. The CIP degradation curve followed pseudo first-order degradation kinetics. The electric efficiency per order (EE/O) of the electrochemical oxidation system was calculated to determine an optimal operation condition. Moreover, the oxidation intermediates were identified with a mass spectrometry (LC/MS/MS) and the degradation pathways were proposed in this study. The destruction of quinolone moiety and piperazine ring and fluorine substitution were the three possible degradation pathways during BDD anode oxidation process.

Oxidation Mechanisms of the UV/Free Chlorine Process: Kinetic Modeling and Quantitative Structure Activity Relationships.

Recently, the UV/free chlorine process has gained attention as a promising technology for destroying refractory organic contaminants in the aqueous phase. We have developed a kinetic model based on first-principles to describe the kinetics and mechanisms of the oxidation of organic contaminants in the UV/free chlorine process. Substituted benzoic acid compounds (SBACs) were chosen as the target parent contaminants. We determined the second-order rate constants between SBACs and reactive chlorine species (RCS; including [Formula: see text], [Formula: see text] and [Formula: see text]) by fitting our model to the experimental results. We then predicted the concentration profiles of SBACs under various operational conditions. We analyzed the kinetic data and predicted concentration profiles of reactive radicals ([Formula: see text] and RCS), we found that [Formula: see text] was the dominant radicals for SBACs destruction. In addition, we established quantitative structure activity relationships (QSARs) that can help predict the second-order rate constants for SBACs destruction by each type of reactive radicals using SBACs Hammett constants. Our first-principles-based kinetic model has been verified using experimental data. Our model can facilitate a design for the most cost-effective application of the UV/free chlorine process. For example, our model can determine the optimum chlorine dosage and UV light intensity that result in the lowest energy consumption.

Electrochemical oxidation of Microcystis aeruginosa using a Ti/RuO2 anode: contributions of electrochemically generated chlorines and hydrogen peroxide.

Electrochemical oxidation was proposed as a promising technology for algal control in drinking water treatment. To be effective, the electrogenerated oxidants should have long half-lives and could continually inhibit the growth of algae. In this study, we used the electrochemical system equipped with a Ti/RuO2 anode which focus on generating long half-life chlorines and H2O2. We explored the impact of electrical field and electrogenerated oxidants on algal inhibition, and we investigated the production of electrogenerated reactive species and their contributions to the inhibition of Microcystis aeruginosa (M. aeruginosa) in simulated surface water with low Cl- concentrations (< 18 mg/L). We developed a kinetic model to simulates the concentrations of chlorines and H2O2. The results showed that electrical field and electrogenerated oxidants were both important contributors to algal inhibition during electrochemical oxidation treatment. The Ti/RuO2 anode mainly generates chlorines and H2O2 from Cl- and water. During the electrolysis at current density of 20 mA/cm2, when initial Cl- concentrations increased from 0 to 18 mg/L (0-5.07 × 10-4 mol/L), the chlorines increased from 0 to 3.62 × 10-6 mol/L, and the H2O2 concentration decreased from 3.68 × 10-6 to 1.15 × 10-6 mol/L. Our model made decent predictions of other Cl- concentrations by comparing with experiment data which validated the rationality of this modeling approach. The electrogenerated chlorine species were more effective than H2O2 at an initial Cl- concentration of 18 mg/L.

Electrocatalytic dechlorination of halogenated antibiotics via synergistic effect of chlorine-cobalt bond and atomic H.

Although noble metal electrocatalysts are highly efficient in the dehalogenation of halogenated antibiotics, the prohibitive cost hinders their practical applications. In this study, a cobalt-phosphorous/oxide (CoP/O) composite prepared via a one-step electrodeposition was for the first time applied in electroreductive dechlorination of halogenated antibiotics (HA), including chloramphenicol (CAP), florfenicol (FLO) and thiamphenicol (TAP). CoP/O had a higher FLO dechlorination efficiency (91%) than Pd/C (69.3%) (t = 60 min, C0 = 20 mg L-1, applied voltage of -1.2 V vs. saturated calomel electrode (SCE)). Furthermore, the dechlorination efficiencies of CoP/O for CAP and TAP reached to 98.7 and 74.2%, respectively. The electron spin resonance and in situ Raman characterizations confirmed that atomic H* was produced via the CoP and the formation of CoCl bonds occurred on the CoO in CoP/O. The CoCl bond formation could trap HA molecules onto CoP/O and weaken the CCl bond strength. The synergistic effect of H* attack and CoCl bond was responsible for the high dechlorination efficiency. This study offers new insights into the interface mechanism of electroreductive dehalogenation process, and shows a great potential for the remediation of halogenated antibiotics contaminated wastewater.

Distribution and sources of polycyclic aromatic hydrocarbons and phthalic acid esters in water and surface sediment from the Three Gorges Reservoir.

After the impoundment of the Three Gorges Reservoir (TGR), the hydrological situation of the reservoir has changed greatly. The concentration and distribution of typical persistent organic pollutants in water and sediment have also changed accordingly. In this study, the concentration, distribution and potential sources of 16 polycyclic aromatic hydrocarbons (PAHs) and 6 phthalic acid esters (PAEs) during the water drawdown and impoundment periods were investigated in water and sediment from the TGR. According to our results, PAHs and PAEs showed temporal and spatial variations. The mean ΣPAH and ΣPAE concentrations in water and sediment were both higher during the water impoundment period than during the water drawdown period. The water samples from the main stream showed larger ΣPAH concentration fluctuations than those from tributaries. Both the PAH and PAE concentrations meet the Chinese national water environmental quality standard (GB 3838-2002). PAH monomers with 2-3 rings and 4 rings were dominant in water, and 4-ring and 5-6-ring PAHs were dominant in sediment. Di-n-butyl phthalate (DBP) and di-2-ethylhexyl phthalate (DEHP) were the dominant PAE pollutants in the TGR. DBP and DEHP had the highest concentrations in water and sediment, respectively. The main source of PAHs in water from the TGR was petroleum and emissions from coal and biomass combustion, whereas the main sources of PAHs in sediments included coal and biomass combustion, petroleum, and petroleum combustion. The main source of PAEs in water was domestic waste, and the plastics and heavy chemical industries were the main sources of PAEs in sediment.

Impact of Chloride Ions on UV/H2O2 and UV/Persulfate Advanced Oxidation Processes.

Chloride ion (Cl-) is one of the most common anions in the aqueous environment. A mathematical model was developed to determine and quantify the impact of Cl- on the oxidization rate of organic compounds at the beginning stage of the UV/persulfate (PS) and UV/H2O2 processes. We examined two cases for the UV/PS process: (1) when the target organic compounds react only with sulfate radicals, the ratio of the destruction rate of the target organic compound when Cl- is present to the rate when Cl- is not present (designated as rRCl-/ rR) is no larger than 1.942%; and (2) when the target organic compounds can react with sulfate radicals, hydroxyl radicals and chlorine radicals, rRCl-/ rR, can be no larger than 60%. Hence, Cl- significantly reduces the organic destruction rate in the UV/PS process. In the UV/H2O2 process, we found that Cl- has a negligible effect on the organic-contaminant oxidation rate. Our simulation results agree with the experimental results very well. Accordingly, our mathematical model is a reliable method for determining whether Cl- will adversely impact organic compounds destruction by the UV/PS and UV/H2O2 processes.

Closed-Loop Electrochemical Recycling of Spent Copper(II) from Etchant Wastewater Using a Carbon Nanotube Modified Graphite Felt Anode.

Developing effective technologies for treatment of spent etchant in printed circuit boards industries is of paramount for sustainable copper reuse and reducing copper discharge. We developed a novel closed-loop electrochemical cell for on-site regeneration of spent acidic cupric chloride etchant. It does not have any emissions and recycles all the copper using a three-dimensional graphite felt anode decorated with carbon nanotube (CNT/GF). The CNT/GF anode oxidizes Cu(I) to Cu(II) so that the spent cuprous chloride can be converted to cupric chloride and reused. The decorated CNT layer with abundant oxygen-containing functional groups significantly enhanced the electrocatalytic activity for Cu(II)/Cu(I) redox. The CuCl32- is oxidized to CuCl+ at the anode and the CuCl+ is reduced to Cu(0) at the cathode. The closed-loop cycle system converts the catholyte into the anolyte. On average, the energy consumption of Cu(I) oxidation by CNT/GF is decreased by 12%, comparing to that by untreated graphite felt. The oxidation rate of Cu(I) is determined by the current density, and there is no delay for the mass transport of Cu(I). This study highlights the outstanding electrocatalytic performance, the rapid mass-transfer kinetics, and the excellent stability of the CNT/GF electrode, and provides an energy-efficient and zero-emission strategy for the regeneration of etchant waste.

Oxidation of Microcystin-LR via Activation of Peroxymonosulfate Using Ascorbic Acid: Kinetic Modeling and Toxicity Assessment.

Advanced oxidation processes (AOPs) have been widely used for the destruction of organic contaminants in the aqueous phase. In this study, we introduce an AOP on activated peroxymonosulfate (PMS) by using ascorbic acid (H2A) to generate sulfate radicals (SO4•-). Sulfate radicals, hydroxyl radicals (HO•), and ascorbyl radicals (A•-) were found using electron spin resonance (ESR). But we found A•- is negligible in the degradation of microcystin-LR (MCLR) due to its low reactivity. We developed a first-principles kinetic model to simulate the MCLR degradation and predict the radical concentrations. The MCLR degradation rate decreased with increasing pH. The scavenging effect of natural organic matter (NOM) on SO4•- was relatively small compared to that for HO•. Considering both energy consumption and MCLR removal, the optimal H2A and PMS doses for H2A/PMS process were determined at 1.0 × 10-6 M and 1.6 × 10-5 M, respectively. In addition, we determined the toxicity using the protein phosphatase 2A (PP2A) test and the results showed that MCLR was readily detoxified and its oxidation byproducts were not hepatotoxic. Overall, our work provides a new type of AOP and a promising, efficient, and environmental-friendly method for removing microcystins in algae-laden water.

Bioregeneration of spent anion exchange resin for treatment of nitrate in water.

Anion exchange resin treatment is a commonly used technique for removal of nitrate from water. However, spent anion exchange resins are themselves regenerated using brine solution, which produces spent solution containing a high concentration of nitrate and salt. The present study developed a bioregeneration technique for conversion of nitrate on the spent resins to nitrogen gas while eliminating the use of brine solutions. Batch experiments were conducted to investigate the effect of biomass content, pH, salinity, and molar ratio of exogenous organic carbon to nitrate on the kinetics of bioregeneration. The bioregeneration rate decreased when pH increased from 7 to 10. It increased with increasing microbial concentration from 8.3 to 13.8 g/L as volatile suspended solid (VSS) and with decreasing conductivity of the regeneration suspension from 31 to 9 mS/cm. Spent exchange resins were effectively regenerated within 5 h under the optimal conditions and the regenerated resins could be used repeatedly for filtration removal of nitrate from water. A desorption-denitrification model was developed to describe bioregeneration kinetics. Modeling results indicated that the bioregeneration was through desorption of nitrate from the spent resin and subsequent denitrification of the soluble nitrate. Denitrification was the rate-limiting process. This research demonstrated the feasibility of using a biological process to regenerate nitrate-saturated resins.