Transformation of metoprolol in UV/PDS process: Role and mechanisms of degradation and polymerization.

Advanced oxidation processes for the treatment of organic pollutants in wastewater suffer from difficulties in mineralization, potential risks of dissolved residues, and high oxidant consumption. In this study, radical-initiated polymerization is dominated in an UV/peroxydisulfate (PDS) process to eliminate organic pollutant of pharmaceutical metoprolol (MTP). Compared with an ideal degradation-based UV/PDS process, the present process can save four fifths of PDS consumption at the same dissolved organic carbon removal of 47.3%. Simultaneously, organic carbon can be recovered from aqueous solution by separating solid polymers at a ratio of 50% of the initial chemical oxygen demand. The chemical structure of products was analyzed to infer the transformation pathways of MTP. Unlike previous studies on simple organic pollutants that the polymerization can occur independently, the polymerization of MTP is dependent on the partial degradation of MTP, and the main monomer in polymerization is a dominant degradation product (4-(2-methoxyethyl)-phenol, denoted as DP151). The separated solid polymers are formed by repeated oxidation and coupling of DP151 or its derivatives through a series of intermediate oligomers. This proof-of-concept study demonstrates the advantage of polymerization-dominated mechanism on dealing with large organic molecules with complex structures, as well as the potential of UV/PDS process for simultaneous organic pollution reduction and organic carbon recovery from aqueous solution.

Catalytic ozonation of reverse osmosis concentrate from coking wastewater reuse by surface oxidation over Mn-Ce/γ-Al2O3: Effluent organic matter transformation and its catalytic mechanism.

Degradation of organics in high-salinity wastewater is beneficial to meeting the requirement of zero liquid discharge for coking wastewater treatment. Creating efficient and stable performance catalysts for high-salinity wastewater treatment is vital in catalytic ozonation process. Compared with ozonation alone, Mn and Ce co-doped γ-Al2O3 could remarkably enhance activities of catalytic ozonation for chemical oxygen demand (COD) removal (38.9%) of brine derived from a two-stage reverse osmosis treatment. Experimental and theoretical calculation results indicate that introducing Mn could increase the active points of catalyst surface, and introducing Ce could optimize d-band electronic structures and promote the electron transport capacity, enhancing HO• bound to the catalyst surface ([HO•]ads) generation. [HO•]ads plays key roles for degrading the intermediates and transfer them into low molecular weight organics, and further decrease COD, molecular weights and number of organics in reverse osmosis concentrate. Under the same reaction conditions, the presence of Mn/γ-Al2O3 catalyst can reduce ΔO3/ΔCOD by at least 37.6% compared to ozonation alone. Furthermore, Mn-Ce/γ-Al2O3 catalytic ozonation can reduce the ΔO3/ΔCOD from 2.6 of Mn/γ-Al2O3 catalytic ozonation to 0.9 in the case of achieving similar COD removal. Catalytic ozonation has the potential to treat reverse osmosis concentrate derived from bio-treated coking wastewater reclamation.

Insight into micropollutant abatement during ultraviolet light-emitting diode combined electrochemical process: Reaction mechanism, contributions of reactive species and degradation routes.

Electrochemical process coupling with ultraviolet light-emitting diode for micropollutant abatement was evaluated in the treatment of wastewater containing Cl-. Four representative micropollutants, atrazine, primidone, ibuprofen and carbamazepine, were selected as target compounds. The impacts of operating conditions and water matrix on micropollutant degradation were investigated. Fluorescence excitation-emission matrix spectroscopy spectra and high performance size exclusion chromatography were employed to characterize the transformation of effluent organic matter in treatment. The degradation efficiencies of atrazine, primidone, ibuprofen and carbamazepine are 83.6 %, 80.6 %, 68.7 % and 99.8 % after 15 min treatment, respectively. The increment of current, Cl- concentration and ultraviolet irradiance promote the micropollutant degradation. However, the presence of bicarbonate and humic acid inhibit micropollutant degradation. The mechanism of micropollutant abatement was elaborated based on reactive species contributions, density functional theory calculation and degradation routes. Free radicals (HO•, Cl•, ClO• and Cl2•-) could be generated by chlorine photolysis and subsequent propagation reactions. The concentrations of HO• and Cl• are 1.14 × 10-13 M and 2.0 × 10-14 M in optimal condition, respectively, and the total contributions of HO• and Cl• for the degradation of atrazine, primidone, ibuprofen and carbamazepine are 24 %, 48 %, 70 % and 43 %, respectively. The degradation routes of four micropollutants are elucidated based on intermediate identification, Fukui function and frontier orbital theory. Micropollutants can be effectively degraded in actual wastewater effluent, and the small molecule compound proportion increases during effluent organic matter evolution. Compared with photolysis and electrolysis, the coupling of the two processes has potential for energy saving in micropollutant degradation, which shed light on the prospects of ultraviolet light-emitting diode coupling with electrochemical process for effluent treatment.

Abatement of Aromatic Contaminants from Wastewater by a Heat/Persulfate Process Based on a Polymerization Mechanism.

A novel approach to the abatement of pollutants consisting of their conversion to separable solid polymers is explored by a heat/persulfate (PDS) process for the treatment of high-temperature wastewaters. During this process, a simultaneous decontamination and carbon recovery can be achieved with minimal use of PDS, which is significantly different from conventional degradation processes. The feasibility of this process is demonstrated by eight kinds of typical organic pollutants and by a real coking wastewater. For the treatment of the selected pollutants, 30.2-91.9% DOC abatement was achieved with 24.8-91.2% carbon recovery; meanwhile, only 5.2-47.0% of PDS was consumed compared to a conventional degradation process. For the treatment of a real coking wastewater, 71.0% DOC abatement was achieved with 66.0% carbon recovery. With phenol as a representative compound, our polymerization-based heat/PDS process is applicable in a wide pH range (3.5-9.0) with a carbon recovery of >87%. Both SO4•- and HO• can be initiators for polymerization, with different contribution ratios under various conditions. Phenol monomers are semioxidized to form phenolic radicals, which are polymerized via chain transfer or chain growth processes to form separable solid phenol polymers, benzenediol polymers, and cross-linked polymers.

Organics abatement and recovery from wastewater by a polymerization-based electrochemically assisted persulfate process: Promotion effect of chloride ion and its mechanism.

Ubiquitous chloride ion (Cl-) in wastewaters usually inhibits the degradation of organic contaminants and generates numerous toxic chlorinated products in conventional degradation-based advanced oxidation processes (AOPs). Herein, a more Cl- tolerant polymerization-based electrochemical AOP for organic contaminants abatement and simultaneous organic resource recovery was demonstrated with eight typical organic contaminants and two real industrial wastewaters for the first time. This process can significantly promote dissolved organic carbon (DOC) abatement in the presence of Cl-, differing greatly from conventional degradation-based processes. Compared to sulfate radical (SO4•-) (or hydroxyl radical (HO•)), dichloride radical (Cl2•-) derived from Cl- has moderate reactivity towards most contaminants, which facilitates the organics polymerization as it ensures the formation of polymerizable organic radicals while inhibiting their excessive degradation. Thus, high DOC abatement (over 75 %) and high organic resource recovery ratio (48-79 % separable organic-polymer yield) can be achieved for most contaminants. Both soluble chlorinated compounds and solid chlorinated polymers are formed in the presence of Cl-. The chlorinated products (e.g. chlorophenols) can be polymerized as new monomers, thus the concentration of dissolved organic chlorinated products is much lower than that in conventional degradation-based process. The tolerance of the present process to Cl- is tested in real coking wastewaters, and exceeding 60 % of the abated chemical oxygen demand (COD) is obtained in the form of recoverable organic-polymers.

Treatment of contaminants by a cathode/FeIII/peroxydisulfate process: Formation of suspended solid organic-polymers.

Treatment of highly contaminated wastewaters containing refractory or toxic organic contaminants (e.g. industrial wastewaters) is becoming a global challenge. Most technologies focus on efficient degradation of organic contaminants. Here we improve the cathode/FeIII/peroxydisulfate (PDS) technology by turning down the current density and develop an innovative mechanism for organic contaminants abatement, namely polymerization rather than degradation, which allows simultaneous contaminants removal and resource recovery from wastewater. This polymerization leads to organic-particles (suspended solid organic-polymers) formation in bulk solution, which is demonstrated by eight kinds of representative organic contaminants. Taking phenol as a representative, 83% of PDS is saved compared to degradation process, with 87.2% of DOC removal. The formed suspended solid organic-polymers occupy 59.2% of COD of the original organics in solution, and can be easily separated from aqueous solution by sedimentation or filtration. The separated organic-polymers are a series of polymers coupled by phenolic monomers, as confirmed by FTIR and ESI-MS analyzes. The energy contained in the recovered organic polymers (4.76 × 10-5 kWh for 100 mL of 1 mM phenol solution in this study) can fully compensate the consumed electrical energy (2.8 × 10-5 kWh) in the treatment process. A representative polymerization model for this process is established, in which the SO4•- and HO• generated from PDS activation initiate the polymerization and improve the polymerization degree by the production of oligomer intermediates. A practical coking wastewater treatment is carried out to verify the research results and get positive feedback, with 56.0% of DOC abatement and the suspended solid organic-polymers accounts for 42.5% of the total COD in the raw wastewater. The energy consumption (47 kWh/kg COD, including electricity and PDS cost) is lower than the values in previous reports. This study provides a novel method for industrial wastewater treatment based on polymerization mechanism, which is expected to recover resources while removing pollutants with low consumption.

SOX4 as biomarker in hepatitis B virus-associated hepatocellular carcinoma.

Background: Hepatitis B virus infection is associated with liver disease, including cancers. In this study, we assessed the power of sex-determining region Y (SRY)-related high-mobility group (HMG)-box 4(SOX4) gene to predict the clinical course of hepatocellular carcinoma (HCC). Methods: To evaluate the differential expression of SOX4 and its diagnostic and prognostic potential in HCC, we analyzed the GSE14520 dataset. Stratified analysis and joint-effect analysis were done using SOX4 and clinical factor. We then designed a nomogram for predicting the clinical course of HCC. Differential SOX4 expression and its correlation with tumor stage as well as its diagnostic and prognostic value were analyzed on the oncomine and GEPIA websites. Gene set enrichment analysis was explored as well as candidate gene ontology and metabolic pathways modulated by in SOX4 HCC. Results: Our analysis revealed that the level of SOX4 was significantly upregulated in tumor issue (P <0.001). This observation was validated through oncomine dataset and MERAV analysis (all P <0.05). Diagnostic receiver operating characteristic (ROC) analysis of SOX4 suggested it has diagnostic potential in HCC (GSE14520 dataset: P <0.001, area under curve (AUC) = 0.782; Oncomine: (Wurmbach dataset) P = 0.002, AUC = 0.831 and (Mas dataset) P <0.001, AUC = 0.947). In addition, SOX4 exhibited high correlation with overall survival of HBV-associated HCC (adjusted P = 0.004, hazard ratio (HR) (95% confidence interval (CI)) = 2.055 (1.261-3.349) and recurrence-free survival (adjusted P = 0.008, HR (95% CI) = 1.721 (1.151-2.574). These observations which were verified by GEPIA analysis for overall survival (P = 0.007) and recurrence-free survival (P= 0.096). Gene enrichment analysis revealed that affected processes included lymphocyte differentiation, pancreatic endocrine pathways, and insulin signaling pathway. SOX4 prognostic value was evaluated using nomogram analysis for HCC 1, 3, and 5-year, survival. Conclusion: Differential SOX4 expression presents an avenue of diagnosing and predicting clinical course of HCC. In HCC, SOX4 may affect TP53 metabolic processes, lymphocyte differentiation and the insulin signaling pathway.

Prognostic value of Glypican family genes in early-stage pancreatic ductal adenocarcinoma after pancreaticoduodenectomy and possible mechanisms.

BACKGROUND: This study explored the prognostic significance of Glypican (GPC) family genes in patients with pancreatic ductal adenocarcinoma (PDAC) after pancreaticoduodenectomy using data from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO). METHODS: A total of 112 PDAC patients from TCGA and 48 patients from GEO were included in the analysis. The relationship between overall survival and the expression of GPC family genes as well as basic clinical characteristics was analyzed using the Kaplan-Meier method with the log-rank test. Joint effects survival analysis was performed to further examine the relationship between GPC genes and prognosis. A prognosis nomogram was established based on clinical characteristics and prognosis-related genes. Prognosis-related genes were investigated by genome-wide co-expression analysis and gene set enrichment analysis (GSEA) was carried out to identify potential mechanisms of these genes affecting prognosis. RESULTS: In TCGA database, high expression of GPC2, GPC3, and GPC5 was significantly associated with favorable survival (log-rank P = 0.031, 0.021, and 0.028, respectively; adjusted P value = 0.005, 0.022, and 0.020, respectively), and joint effects analysis of these genes was effective for prognosis prediction. The prognosis nomogram was applied to predict the survival probability using the total scores calculated. Genome-wide co-expression and GSEA analysis suggested that the GPC2 may affect prognosis through sequence-specific DNA binding, protein transport, cell differentiation and oncogenic signatures (KRAS, RAF, STK33, and VEGFA). GPC3 may be related to cell adhesion, angiogenesis, inflammatory response, signaling pathways like Ras, Rap1, PI3K-Akt, chemokine, GPCR, and signatures like cyclin D1, p53, PTEN. GPC5 may be involved in transcription factor complex, TFRC1, oncogenic signatures (HOXA9 and BMI1), gene methylation, phospholipid metabolic process, glycerophospholipid metabolism, cell cycle, and EGFR pathway. CONCLUSION: GPC2, GPC3, and GPC5 expression may serve as prognostic indicators in PDAC, and combination of these genes showed a higher efficiency for prognosis prediction.

Determination methods for steady-state concentrations of HO• and SO4•- in electrochemical advanced oxidation processes.

Competitive kinetics and scavenging assay are commonly used for radical quantification. However, the accuracy of the two methods has been challenged in electrochemical advanced oxidation processes (EAOPs) since the strong reactivity of electrode against organic indicators may disrupt the quantitative relationship between indicator consumption and radical concentration. The present study focused on screening suitable indicators and developing suitable methods for determining the steady-state concentrations of SO4•- and HO• ([SO4•-]ss and [HO•]ss) in several EAOPs for water treatment based on competitive kinetics and scavenging assay. The applicability of the modified methods and available indicators were investigated through experimental and kinetic analysis. In anode alone process, the competitive kinetics was more appropriate than scavenging assay and benzoic acid (BA) met the basic requirement of being a competitor to determine the [HO•]ss. In cathode alone process, BA was more resistant to interfering factors than other competitors (ibuprofen, atrazine and nitrobenzene) and its reaction rate involved only the radical oxidation even when the reaction conditions varied over a wide range. Therefore, the [HO•]ss could be obtained by the competitive kinetic equation of BA when HO• existed alone. When HO• coexisted with SO4•-, a two-step method combining scavenging assay and competitive kinetics was proposed to measure [SO4•-]ss and [HO•]ss, in which tert-butyl alcohol and BA were added as scavenger and competitor, respectively. Furthermore, the reliability of each approach was verified by the experimental results and kinetic analysis.

Oncogene PLCE1 may be a diagnostic biomarker and prognostic biomarker by influencing cell cycle, proliferation, migration, and invasion ability in hepatocellular carcinoma cell lines.

Hepatocellular carcinoma (HCC) is a lethal malignancy worldwide. HCC has traits of late diagnosis and high recurrence. This study explored potential diagnosis and prognosis significance of phospholipase C epsilon 1 (PLCE1) in HCC. The messenger RNA (mRNA) levels and diagnostic value of PLCE1 were determined by real-time polymerase chain reaction and online databases GEPIA, oncomine, and GSE14520 data set. Survival analysis used the Kaplan-Meier Plotter website. Cell cycle, proliferation, migration, and invasion assays were performed with downregulated PLCE1 expression in HCC-M and HepG2 cell lines. PLCE1 was differentially expressed and highly expressed in tumors and had low expression in nontumor tissues (all p < .05). The diagnostic value of PLCE1 was validated with the datasets (all p < .01, all areas under curves > 0.7). PLCE1 mRNA expression was associated with the overall and relapse-free survival (both p < .05). Functional experiments indicated that downregulation of PLCE1 expression led to increased G1 stage in cell cycle and decreased cell proliferation, migration, and invasion compared with a negative control group (all p ≤ .05). The oncogene PLCE1 was differentially expressed in HCC and non-HCC tissues. It is a candidate for diagnosis and serves as prognosis biomarker. PLCE1 influenced survival by affecting the cell cycle, proliferation, migration, and invasion ability.

Comprehensive investigation of p53, p21, nm23, and VEGF expression in hepatitis B virus-related hepatocellular carcinoma overall survival after hepatectomy.

Objective: The goal of our current study is to assess the immunohistochemical of p53, p21, nm23, and VEGF expression in hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) prognosis after hepatectomy, as well as the prospective molecular mechanisms of prognostic indicator. Methods: There were 419 HBV-related HCC patients who were from southern China of Guangxi province and were used to evaluate the immunohistochemical expression for these biomarkers in prognosis. A genome-wide expression microarray dataset of HBV-related HCC were obtained from GSE14520. Results: In our study, the expression of p53, p21, and nm23 in cancer tissues of patients with hepatitis B-related hepatocellular carcinoma did not affected the clinical outcome of 2 years, 5 years or overall. Patients with high expression of VEGF had a worse overall survival after 2 years of surgery than patients with low expression (adjusted P=0.040, adjusted HR = 1.652, 95% CI = 1.024-2.665). Survival analysis of VEGF in GSE14520 cohort also demonstrated that VEGF mRNA expression also significantly associated with HBV-related HCC OS (adjusted P=0.035, adjusted HR =1.651, 95% CI =1.035-2.634). The prospective molecular mechanisms by co-expression analysis suggested that VEGF might be correlated to regulation of cell proliferation, cell growth and apoptotic process, Rap1 signaling pathway, HIF-1 signaling pathway, PPAR signaling pathway, cell cycle. Whereas the GSEA suggested that VEGF might involve in the regulation of HIF and HIF1A pathway, and TP53 regulation pathway. Conclusion: Our findings suggested that VEGF might be a prognostic indicator of HBV-related HCC, and we also identified the VEGF prospective molecular mechanisms through the whole genome co-expression and GSEA approaches.

Diagnostic and prognostic biomarkers of Human Leukocyte Antigen complex for hepatitis B virus-related hepatocellular carcinoma.

Background: Hepatitis B virus infection had been identified its relationship with liver diseases, including liver tumors. We aimed to explore diagnostic and prognostic values between the Human Leukocyte Antigen (HLA) complex and hepatocellular carcinoma (HCC). Methods: We used the GSE14520 dataset to explore diagnostic and prognostic significance between HLA complex and HCC. A nomogram was constructed to predict survival probability of HCC prognosis. Gene set enrichment analysis was explored using gene ontologies and metabolic pathways. Validation of prognostic values of the HLA complex was performed in the Kaplan-Meier Plotter website. Results: We found that HLA-C showed the diagnostic value (P <0.0001, area under curve: 0.784, sensitivity: 93.14%, specificity: 62.26%). In addition, HLA-DQA1 and HLA-F showed prognostic values for overall survival, and HLA-A, HLA-C, HLA-DPA1 and HLA-DQA1 showed prognostic values for recurrence-free survival (all P ≤ 0.05, elevated 0.927, 0.992, 1.023, 0.918, 0.937 multiples compared to non-tumor tissues, respectively). Gene set enrichment analysis found that they were involved in antigen processing and toll like receptor signalling pathway, etc. The nomogram was evaluated for survival probability of HCC prognosis. Validation analysis indicated that HLA-C, HLA-DPA1, HLA-E, HLA-F and HLA-G were associated with HCC prognosis of overall survival (all P ≤ 0.05, elevated 0.988 and 0.997 multiples compared to non-tumor tissues, respectively). Conclusion: HLA-C might be a diagnostic and prognostic biomarker for HCC. HLA-DPA1 and HLA-F might be prognostic biomarkers for HCC.

Comparison of inert and non-inert cathode in cathode/Fe3+/Peroxymonosulfate processes on iohexol degradation.

To investigate the effect of cathode materials on organics degradation in a cathode/Fe3+/PMS process, different cathode materials (platinum, copper and iron) were selected and their performances were compared with iohexol as target organics. The optimal conditions were found to be different for different cathode/Fe3+/PMS processes. With a relatively high cathodic current input (2.0 mA/cm2), similar results were found for all the three cathode/Fe3+/PMS processes. With a small cathodic current input (not higher than 1.0 mA/cm2), the iohexol removal followed the order of Fe-cathode/Fe3+/PMS > Cu-cathode/Fe3+/PMS > Pt-cathode/Fe3+/PMS, due to the corrosion of Cu-cathode and Fe-cathode and the more serious corrosion of Fe-cathode than Cu-cathode. The corrosion of non-inert cathode materials (Cu-cathode and Fe-cathode) meant that these cathodes not only transmitted electrons but also participated in aqueous reactions, which complicated the mechanisms of cathode/Fe3+/PMS processes. The radical identification experiments indicated that SO4- was more important than OH for iohexol degradation in Cu-cathode/Fe3+/PMS process, while OH played a major role in Pt-cathode/Fe3+/PMS and Fe-cathode/Fe3+/PMS processes. The different reaction mechanisms resulted in different iohexol transformation pathways in cathode/Fe3+/PMS processes with different cathode materials.

Potential of the integration of coagulation and ozonation as a pretreatment of reverse osmosis concentrate from coal gasification wastewater reclamation.

Combination of coagulation and ozonation was used to treat brine derived from a three-stage reverse osmosis (RO) process during coal gasification wastewater reclamation. Effects of operating parameters on the removals of total organic carbon (TOC), color and UV absorbance at 254 nm (A254) were investigated during coagulation and ozonation. All the removal efficiencies of TOC, A254 and color of FeCl3 coagulant are about twice those of AlCl3 coagulant at the same molar dose since almost all the molecular weight fractions of RO concentrate (ROC) could be removed effectively by FeCl3 coagulant while only the fractions of molecular weight > 3 k Da could be removed effectively by AlCl3 coagulant. The TOC removal increases with the increasing of ozone dose and reaction temperature during ozonation of ROC after coagulation pretreatment. TOC and color of ROC after pretreated by coagulation could be further removed effectively during ozonation since ozonation can significant reduce the fluorescence response of all the fractions of effluent organic matter in ROC. It is unexpectedly found that the increase of A254 is observed after ozonation, this is because the intensity of absorbance at 254 nm by the low molecular weight transformation products (<2 k Da) increases significantly with the reaction time after 30 min. The coagulation coupling with ozonation is efficient in the removals of both TOC and color of ROC.

Performance of Cu-cathode/Fe3+/peroxymonosulfate process on iohexol degradation.

Copper was used as a non-inert cathode material in a Cathode/Fe3+/peroxymonosulfate(PMS) system, and the performance of this novel Cu-cathode/Fe3+/PMS system was tested with a typical iodinated X-ray contrast media (iohexol) as target organics. The reaction mechanisms and the iohexol degradation pathways were investigated. The operational conditions of Cu-cathode/Fe3+/PMS process on iohexol degradation were optimized to be 1.0 mM Fe3+ dosage, 3.0 mM PMS dosage and 0.50 mA/cm2 of current input. The much lower current applied in the present study than previous reports would help to save energy and be more economical. Compared with typical inert cathode (Pt-cathode), the Cu-cathode/Fe3+/PMS process has better performance on both iohexol removal and deiodination, due to that Cu-cathode participated in Fe2+ regeneration and PMS activation via surface Cu°-Cu+(s)-Cu2+-Cu° redox cycle. Fe2+ could be produced via reactions between Fe3+ and Cu/Cu+(s) as well as cathodic reduction of Fe3+. SO4- was generated from PMS activation by Fe2+, Cu/Cu+(s) and cathodic reduction. OH was also generated in this process but SO4- played a dominant role in iohexol degradation. The intermediate products of iohexol and its transformation pathways were complex due to the varied reaction mechanisms involving both oxidation and reduction in Cu-cathode/Fe3+/PMS process.

Formation of brominated trihalomethanes during chlorination or ozonation of natural organic matter extracts and model compounds in saline water.

Oxidation experiments (chlorine, ozone and bromine) were carried out with synthetic saline waters containing natural organic matter (NOM) extracts and model compounds to evaluate the potential of these surrogates to mimic the formation of brominated trihalomethanes (Br-THMs) in natural saline waters. Synthetic saline water with Pony Lake fulvic acid (PLFA) showed comparable results to natural brackish and sea water for Br-THMs formation during chlorination and ozonation for typical ballast water treatment conditions ([Cl2]0 ≥ 5 mg/L or [O3]0 ≥ 3 mg/L). The molar CHBr3 yield in synthetic saline waters is higher for chlorination than for ozonation, since ozone reacts slower with bromide and faster with THM precursors. For bromination, the molar yields of CHBr3 for the NOM model compounds phenol, resorcinol, 3-oxopentanedioic acid and hydroquinone are 28, 62, 91 and 11%, respectively. CHBr3 formation is low during chlorination or ozonation of resorcinol-containing synthetic saline waters due to the faster reaction of resorcinol with these oxidants compared to the bromine formation from bromide. Oxidation experiments with mixtures of hydroquinone and phenol (or resorcinol) were conducted to mimic various functional groups of NOM reacting with Cl2 (or O3) in saline water. With increasing hydroquinone concentrations, the CHBr3 formation increases during both chlorination and ozonation of the mixtures, except for chlorination of the mixture of hydroquinone and resorcinol. The formation of THMs during chlorination of the mixture of hydroquinone and resorcinol is similar to that of resorcinol alone due to the much faster reaction of HOX with resorcinol compared to hydroquinone. In general, PLFA seems to be a reasonable DOM surrogate to simulate CHBr3 formation for realistic ballast water treatment. During chlorination, CHBr3 formations from phenol- and PLFA-containing synthetic brackish waters are comparable, for similar phenol contents.

Peracetic acid oxidation of saline waters in the absence and presence of H 2O 2: secondary oxidant and disinfection byproduct formation.

Peracetic acid (PAA) is a disinfectant considered for use in ballast water treatment, but its chemical behavior in such systems (i.e., saline waters) is largely unknown. In this study, the reactivity of PAA with halide ions (chloride and bromide) to form secondary oxidants (HOCl, HOBr) was investigated. For the PAA-chloride and PAA-bromide reactions, second-order rate constants of (1.47 ± 0.58) × 10(-5) and 0.24 ± 0.02 M(-1) s(-1) were determined for the formation of HOCl or HOBr, respectively. Hydrogen peroxide (H2O2), which is always present in PAA solutions, reduced HOCl or HOBr to chloride or bromide, respectively. As a consequence, in PAA-treated solutions with [H2O2] > [PAA], the HOBr (HOCl) steady-state concentrations were low with a limited formation of brominated (chlorinated) disinfection byproducts (DBPs). HOI (formed from the PAA-iodide reaction) affected this process because it can react with H2O2 back to iodide. H2O2 is thus consumed in a catalytic cycle and leads to less efficient HOBr scavenging at even low iodide concentrations (<1 µM). In PAA-treated solutions with [H2O2] < [PAA] and high bromide levels, mostly brominated DBPs are formed. In synthetic water, bromate was formed from the oxidation of bromide. In natural brackish waters, bromoform (CHBr3), bromoacetic acid (MBAA), dibromoacetic acid (DBAA), and tribromoacetic acid (TBAA) formed at up to 260, 106, 230, and 89 µg/L, respectively for doses of 2 mM (ca. 150 mg/L) PAA and [H2O2] < [PAA]. The same brackish waters, treated with PAA with [H2O2] ≫ [PAA], similar to conditions found in commercial PAA solutions, resulted in no trihalomethanes and only low haloacetic acid concentrations.

Oxidative degradation of organic pollutants in aqueous solution using zero valent copper under aerobic atmosphere condition.

Oxidative degradation of organic pollutants and its mechanism were investigated in aqueous solution using zero valent copper (ZVC) under aerobic atmosphere condition. Diethyl phthalate (DEP) was completely oxidized after 120 min reaction by ZVC at initial pH 2.5 open to the air. DEP degradation followed the pseudo-first-order kinetics after the lag period, and the degradation rate of DEP increased gradually with the increase of ZVC dosage, and the decrease of initial pH from 5.8 to 2.0. ZVC required a shorter induction time and exhibited persistent oxidation capacity compared to that of zero valent iron and zero valent aluminium. The mechanism investigation showed that remarkable amount of Cu(+)/Cu(2+) and H2O2 were formed in ZVC acidic system, which was due to the corrosive dissolution of ZVC and the concurrent reduction of oxygen. The addition of tert-butanol completely inhibited the degradation of DEP and the addition of Fe(2+) greatly enhanced the degradation rate, which demonstrated that hydroxyl radical was mainly responsible for the degradation of DEP in ZVC acidic system under aerobic atmosphere condition, and the formation of hydroxyl radical was attributed to the Fenton-like reaction of in situ formed Cu(+) with H2O2.

Enhanced ozonation degradation of di-n-butyl phthalate by zero-valent zinc in aqueous solution: performance and mechanism.

Enhanced ozonation degradation of di-n-butyl phthalate (DBP) by zero-valent zinc (ZVZ) has been investigated using a semi-continuous reactor in aqueous solution. The results indicated that the combination of ozone (O3) and ZVZ showed an obvious synergetic effect, i.e. an improvement of 54.8% on DBP degradation was obtained by the O3/ZVZ process after 10min reaction compared to the cumulative effect of O3 alone and O2/ZVZ. The degradation efficiency of DBP increased gradually with the increase of ZVZ dosage, enhanced as solution pH increasing from 2.0 to 10.0, and more amount of DBP was degraded with the initial concentration of DBP arising from 0.5 to 2.0mgL(-1). Recycling use of ZVZ resulted in the enhancement of DBP degradation, because the newly formed zinc oxide took part in the reaction. The mechanism investigation demonstrated that the enhancement effect was attributed to the introduction of ZVZ, which could promote the utilization of O3, enhance the formation of superoxide radical by reducing O2 via one-electron transfer, accelerate the production of hydrogen peroxide and the generation of hydroxyl radical. Additionally, the newly formed zinc oxide on ZVZ surface also contributed to the enhancement of DBP degradation in the recycling use of ZVZ. Most importantly, the O3/ZVZ process was also effective in enhanced ozonation degradation of DBP under the background of actual waters.

Reuse of sewage sludge as a catalyst in ozonation--efficiency for the removal of oxalic acid and the control of bromate formation.

Sewage derived sludge is produced with an annual amount increase of 2% all over the world and it is an urgent issue to be addressed by human being. In the present study, sludge was converted into sludge-based catalyst (SBC) with ZnCl2 as activation agent and characterized by several methods (e.g., scanning electron microscope, X-ray photoelectron spectroscope and Fourier transform infrared spectroscope). Then it was used as a catalyst to enhance the removal of refractory organic matter, oxalic acid, and to control the formation of bromate (BrO3-) in bench semi-continuous ozonation experiments. The effects of various operating parameters on the control of BrO3- formation were investigated. Furthermore, the mechanism for the enhancement of organic matter removal and the control of BrO3- formation was discussed as well. Results indicate that the combination of SBC with ozone shows a strong synergistic effect, resulting in a notable improvement on oxalic acid removal. A crucial surface reaction mechanism for the enhancement of organic matter removal is proposed on the basis of negative effect of higher pH and no inhibition effect of tert-butanol. The control for BrO3- formation was demonstrated and the reason for its control in the process of O3/SBC is the combined effect of SBC reductive properties, ozone exposure decrease and hydrogen peroxide concentration increase.