The efficient mineralization of phenol and its derivatives in wastewater remains a great challenge.In this study,the bimetallic CuCeO_(2)-BTC was screened from a series of MOFs-derived MCeO_(2)-BTC(M=La,Cu,Co,Fe,and M...The efficient mineralization of phenol and its derivatives in wastewater remains a great challenge.In this study,the bimetallic CuCeO_(2)-BTC was screened from a series of MOFs-derived MCeO_(2)-BTC(M=La,Cu,Co,Fe,and Mn)catalysts,and the influence of the Cu/Ce ratio on phenol removal by catalytic ozonation was carefully examined.The results indicate that Cu_(2)Ce_(1)O_(y)-BTC was the best among the Cu_(x)Ce_(1)O_(y)-BTC(x=0,1,2,and 3)catalysts,with a phenol mineralization efficiency reaching close to 100%within 200 min,approximately 30.1%higher than CeO_(2)-BTC/O_(3)and 70.3%higher than O_(3)alone.The order of mineralization efficiency of phenol was Cu_(2)Ce_(1)O_(y)-BTC>Cu_(3)Ce_(1)O_(y)-BTC>Cu_(1)Ce_(1)O_(y)-BTC>CeO_(2)-BTC.CeO_(2)-BTC exhibited a broccoli-like morphology,and Cu_(x)Ce_(1)O_(y)-BTC(x=1,2,and 3)exhibited an urchin-like morphology.Compared with Cu_(x)Ce_(1)O_(y)-BTC(x=0,1,and 3),Cu_(2)Ce_(1)O_(y)-BTC exhibited a larger specific surface area and pore volume.This characteristic contributed to the availability of more active sites for phenol degradation.The redox ability was greatly enhanced as well.Besides,the surface of Cu_(2)Ce_(1)O_(y)-BTC exhibited a higher concentration of Ce^(3+)species and hydroxyl groups,which facilitated the dissociation of ozone and the generation of active radicals.Based on the results of radical quenching experiments and the intermediates detected by LC-MS,a potential mechanism for phenol degradation in the Cu_(2)Ce_(1)O_(y)-BTC/O_(3)system was postulated.This study offers novel perspectives on the advancement of MOFs-derived catalysts for achieving the complete mineralization of phenol in wastewater through catalytic ozonation.展开更多
In response to the fact that the presence of manganese dithionate(MnS_(2)O_(6))leads to a series of adverse impacts,especially lower purity of manganese sulfate(MnSO_(4))and disruption of its recovery,advanced oxidati...In response to the fact that the presence of manganese dithionate(MnS_(2)O_(6))leads to a series of adverse impacts,especially lower purity of manganese sulfate(MnSO_(4))and disruption of its recovery,advanced oxidation methods such as ozonation system are used to manage MnS_(2)O_(6)in the leaching solution,replacing conventional methods.To ascertain the conversion rate and kinetics of MnS_(2)O_(6)during the ozonation process,we explored the factors influencing its removal rate,including ozone dosage,manganese dithionate concentration,sulfuric acid concentration,and reaction temperature.Batch experiments were conducted to determine the reaction rate constant of ozone(k)and activation energy(Ea)obtained from intermittent experimental data fitting,revealing a least-squares exponential conversion relationship between k and the MnS_(2)O_(6)removal amount,wherein an increase in the aforementioned factors led to an enhanced MnS_(2)O_(6)conversion rate,exceeding 99.3%.The formation mechanism of the ozone products proposed during the experiment was summarized and proposed as follows:1)Mn^(2+)was directly oxidized to MnO_(2),and 2)SO_(4)2−was obtained by the catalytic oxidation of S_(2)O_(6)^(2−)with HO•from O3 decomposition.According to the kinetics analysis,the pre-exponential factor and total activation energy of the ozonation kinetics equation were 1.0×10^(23) s^(−1) and 177.28 kJ/mol,respectively.Overall,the present study demonstrates that O_(3) as an oxidizing agent can effectively facilitate MnS_(2)O_(6)disproportionation while preventing the release of the secondary pollutant,SO_(2)gas.展开更多
This study aims to identify the highly non-specific toxic by-products during ozonation of three cresols in wastewater.In ozonated effluents,biotoxicity increased along with increasing reaction time,followed by a gradu...This study aims to identify the highly non-specific toxic by-products during ozonation of three cresols in wastewater.In ozonated effluents,biotoxicity increased along with increasing reaction time,followed by a gradual decrease.The peak biotoxicity for ozonated o-cresol(o-C),m-cresol(m-C),and p-cresol(p-C)was estimated to be 17.4,14.8 and 5.5 times higher than that of untreated wastewater,respectively.A redox-directed approach with high-resolution mass spectrometry detection and toxicity prediction revealed that monomeric para-benzoquinones(p-BQs),hydroxylated p-BQs,and dimeric p-BQs in ozonated cresols were the primary contributors to the increased toxicity.Calculations based on density functional theory indicated formation pathways of p-BQs byproducts,e.g.,the formation of 2-methyl-p-benzoquinone was likely induced by ozone molecules rather than hydroxyl radicals in ozonated o-C and m-C,and the formation of p-BQs during ozonation of p-C was attributed to the oxidation of methyl group to carboxyl group and subsequent decarboxylation initiated by hydroxyl radicals.Electron paramagnetic resonance and spin density calculation showed that the presence of carbon-centered cresoxyl radicals was responsible for dimeric p-BQs formation.Collectively,these results underscore significant contribution of non-halogenated p-BQs to non-specific toxicity increase in ozonated effluents.展开更多
Photocatalytic ozonation holds promise for advanced water purification,yet its development has been hindered by a limited understanding of ozone activation mechanisms and its related photogenerated electron transfer d...Photocatalytic ozonation holds promise for advanced water purification,yet its development has been hindered by a limited understanding of ozone activation mechanisms and its related photogenerated electron transfer dynamics.Herein,we employed in-situ DRIFTS and Raman spectroscopy to elucidate the distinct adsorption and activation behaviors of ozone(O_(3))on the{001}and{110}crystal facets of Bi_(2)O_(2)CO_(3)(BOC)nanosheets.BOC-{001}demonstrates superior photocatalytic ozonation performance,with 85%phenol mineralization and excellent durability,significantly outperforming the 53%mineralization rate of BOC-{110}.This enhanced activity is attributed to non-dissociative ozone adsorption and favorable adsorption energy over{001}facet,which facilitate the one-electron O_(3) reduction pathway.Furthermore,crystal facet engineering strengthens the built-in electric field,promoting exciton dissociation and the generation of localized charge carriers.The synergistic effects of optimized electron availability and ozone adsorption significantly boost the production of reactive oxygen species.These findings provide a deeper understanding of the critical roles of O_(3) adsorption and electron transfer in radical generation,which could provide some guidance for the strategic development of highly effective photocatalytic ozonation catalysts.展开更多
Nowadays,it is still a challenge to prepared high efficiency and low cost formaldehyde(HCHO)removal catalysts in order to tackle the long-living indoor air pollution.Herein,δ-MnO_(2)is successfully synthesized by a f...Nowadays,it is still a challenge to prepared high efficiency and low cost formaldehyde(HCHO)removal catalysts in order to tackle the long-living indoor air pollution.Herein,δ-MnO_(2)is successfully synthesized by a facile ozonation strategy,where Mn^(2+)is oxidized by ozone(O_(3))bubble in an alkaline solution.It presents one of the best catalytic properties with a low 100%conversion temperature of 85℃for 50 ppm of HCHO under a GHSV of 48,000 mL/(g·hr).As a comparison,more than 6 times far longer oxidation time is needed if O3 is replaced by O_(2).Characterizations show that ozonation process generates a different intermediate of tetragonalβ-HMnO_(2),which would favor the quick transformation into the final productδ-MnO_(2),as compared with the relatively more thermodynamically stable monoclinicγ-HMnO_(2)in the O_(2)process.Finally,HCHO is found to be decomposed into CO_(2)via formate,dioxymethylene and carbonate species as identified by room temperature insitu diffuse reflectance infrared fourier transform spectroscopy.All these results show great potency of this facile ozonation routine for the highly activeδ-MnO_(2)synthesis in order to remove the HCHO contamination.展开更多
To convert the non biodegradable sodium lignin sulfonate into biodegradable substances, the sodium lignin sulfonate in the water was ozonized and the pH value, dissolved organic carbon(DOC), ultraviolet absorbency at...To convert the non biodegradable sodium lignin sulfonate into biodegradable substances, the sodium lignin sulfonate in the water was ozonized and the pH value, dissolved organic carbon(DOC), ultraviolet absorbency at λ =254 nm(UVA) and the biodegradability of the ozonation effluent were measured. The non biodegradable sodium lignin sulfonate can be partly converted into biodegradable substances by ozonation (about 38 76%). In the ozonation process, there is little DOC decrease, but much UVA decrease and obvious pH drop.展开更多
A study on advanced drinking water treatment was conducted in a pilot scale plant taking water from conventional treatment process. Ozonation-biological activated carbon process （O3-BAC） and granular activated carbo...A study on advanced drinking water treatment was conducted in a pilot scale plant taking water from conventional treatment process. Ozonation-biological activated carbon process （O3-BAC） and granular activated carbon process （GAC） were evaluated based on the following parameters： CODMn, UV254, total organic carbon （TOC）, assimilable organic carbon （AOC） and biodegradable dissolved organic carbon （BDOC）. In this test, the average removal rates of CODMn, UV254 and TOC in O3-BAC were 18.2%, 9.0% and 10.2% higher on （AOC） than in GAC, respectively. Ozonation increased 19.3-57.6 μg Acetate-C/L in AOC-P17, 45.6-130.6 μg Acetate-C/L in AOC-NOX and 0.1-0.5 mg/L in BDOC with ozone doses of 2 8 mg/L. The optimum ozone dose for maximum AOC formation was 3 mgO3/L. BAC filtration was effective process to improve biostability.展开更多
The degradation mechanism of Cationic Red X-GRL was investigated when the intermediates, the nitrate ion and the pH were analyzed in the ozonation. The degradation of the Cationic Red X-GRL includes the de-auxochrome...The degradation mechanism of Cationic Red X-GRL was investigated when the intermediates, the nitrate ion and the pH were analyzed in the ozonation. The degradation of the Cationic Red X-GRL includes the de-auxochrome stage, the decolour stage, and the decomposition of fragment stage. During the degradation process, among the six nitrogen atoms of Cationic Red X-GRL, one is transferred into a nitrate ion, one becomes the form of an amine compound, and the rest four are transformed into two molecules of nitrogen. In the course of the ozonation of Cationic Red X-GRL, the direct attack of ozone is the main decolour effect.展开更多
A three phase fluidized bed reactor was used to investigate the combined effect of adsorption and oxidation for phenolic wastewater treatment.Aqueous solutions containing 10 mg·L 1of phenol and ozone were continu...A three phase fluidized bed reactor was used to investigate the combined effect of adsorption and oxidation for phenolic wastewater treatment.Aqueous solutions containing 10 mg·L 1of phenol and ozone were continuously fed co-currently as upward flow into the reactor at constant flow rate of 2 and 1 L·min 1,respectively.The phenolic treatment results in seven cases were compared：（a）O3 only,（b）fresh granular activated carbon（GAC）,（c） 1st reused GAC,（d）2nd reused GAC,（e）fresh GAC enhanced with O3,（f）1st reused GAC enhanced with O3,and （g）2nd reused GAC enhanced with O3.The phenolic wastewater was re-circulated through the reactor and its concentration was measured with respect to time.The experimental results revealed that the phenolic degradation using GAC enhanced with O3 provided the best result.The effect of adsorption by activated carbon was stronger than the effect of oxidation by ozone.Fresh GAC could adsorb phenol better than reused GAC.All cases of adsorption on GAC followed the Langmuir isotherm and displayed pseudo second order adsorption kinetics.Finally,a differential equation for the fluidized bed reactor model was used to describe the phenol concentration with respect to time for GAC enhanced with O3.The calculated results agree reasonably well with the experimental results.展开更多
The catalytic ozonation treatment of secondary biochemical effluent for papermaking wastewater by Ag-doped nickel ferrite was investigated.Ag-doped catalysts prepared by sol-gel method were characterized,illustrating ...The catalytic ozonation treatment of secondary biochemical effluent for papermaking wastewater by Ag-doped nickel ferrite was investigated.Ag-doped catalysts prepared by sol-gel method were characterized,illustrating that Ag entirely entered the crystalline of Ni Fe2O4 and changed the surface properties.The addition of catalyst enhanced the removal efficiency of chemical oxygen demand and total organic carbon.The results of gas chromatography-mass spectrometer,ultraviolet light absorbance at 254 nm and threedimensional fluorescence excitation-emission matrix suggested that aromatic compounds were efficiently degraded and toxic substances,such as dibutyl phthalate.In addition,the radical scavenging experiments confirmed the hydroxyl radicals acted as the main reactive oxygen species and the surface properties of catalysts played an important role in the reaction.Overall,this work validated potential applications of Ag-doped Ni Fe2O4 catalyzed ozonation process of biologically recalcitrant wastewater.展开更多
Fe3O4-CoO/Al2O3 catalyst was prepared by incipient wetness impregnation using Fe（NO3）3.9H2O and Co（NO3）2.6H2O as the precursors, and its catalytic performance was investigated in ozonation of 2-（2,4-dichlorophen...Fe3O4-CoO/Al2O3 catalyst was prepared by incipient wetness impregnation using Fe（NO3）3.9H2O and Co（NO3）2.6H2O as the precursors, and its catalytic performance was investigated in ozonation of 2-（2,4-dichlorophenoxy）propionic acid （2,4-DP）, nitrobenzene and oxalic acid. The experimental results indicated that Fe3O4-CoO/Al2O3 catalyst enabled an interesting improvement of ozonation efficiency during the degradation of each organic pollutant, and the Fe3O4-CoO/Al2O3 catalytic ozonation system followed a radical-type mechanism. The kinetics of ozonation alone and Fe3O4-CoO/Al2O3 catalytic ozonation of three organic pollutants in aqueous solution were discussed under the mere consideration of direct ozone reaction and OH radical reaction to well investigate its performance. In the catalytic ozonation of 2,4-DP, the apparent reaction rate constants （k） were determined to be 1.456 × 10^-2 min-1 for ozonation alone and 4.740 × 10^-2 min^-1 for O3/Fe3O4-CoO/Al2O3. And O3/Fe3O4-CoO/Al2O3 had a larger Rot （6.614 × 10^-9） calculated by the relative method than O3 did （1.800 x 10-9）, showing O3/Fe3O4-CoO/Al2O3 generated more hydroxyl radical. Similar results were also obtained in the catalytic ozonation of nitrobenzene and oxalic acid. The above results demonstrated that the catalytic performance of Fe3O4-CoO/Al2O3 in ozonation of studied organic substance was universal to a certain degree.展开更多
A novel heterogeneous catalytic ozonation process in water treatment was studied, with a copper-loaded activated carbon （Cu/AC） that was prepared by an incipient wetness impregnation method at low temperature and te...A novel heterogeneous catalytic ozonation process in water treatment was studied, with a copper-loaded activated carbon （Cu/AC） that was prepared by an incipient wetness impregnation method at low temperature and tested as a catalyst in the ozonation of phenol and oxalic acid. Cu/AC was characterized using XRD, BET and SEM techniques. Compared with ozonation alone, the presence of Cu/AC in the ozonation processes significantly improves the degradation of phenol or oxalic acid. With the introduction of the hydroxyl radical scavenger, i.e., turt-butanol alcohol （t-BuOH）, the degradation efficiency of both phenol and oxalic acid in the Cu/AC catalyzed ozonation process decreases by 22% at 30 min. This indicates that Cu/AC accelerates ozone decomposition into certain concentration of hydroxyl radicals. The amount of Cu（II ） produced during the reaction of Cu/AC-catalyzed ozonation of phenol or oxalic acid is very small, which shows that the two processes are both heterogeneous catalytic ozonation reactions.展开更多
Ozonation of synthetic water containing a type of endocrine disruptor-di-n-butyl phthalate （DBP） was examined. Key impact factors such as pH, temperature, ionic strength, ozone dosage and initial DBP concentration w...Ozonation of synthetic water containing a type of endocrine disruptor-di-n-butyl phthalate （DBP） was examined. Key impact factors such as pH, temperature, ionic strength, ozone dosage and initial DBP concentration were investigated. In addition, the activities of radicals on uncatalysed and catalysed ozonation were studied. The degradation intermediate products were followed and the kinetic of the ozonation were assessed as well. Results revealed that ozonation of DBP followed two mechanisms. Firstly, the reaction rate of direct ozonation was slower at lower pH, temperature, and ionic strength. Secondly, when these factors were increased for indirect radical reaction, higher percentage of DBP was removed with the increase of the initial ozone dosage and the decrease of the initial DBP concentration. In addition, tea-butanol, humic substances and Fe（Ⅱ） affected DBP ozonation through the radical pathway. It was determined that ozonation was restrained by adding tea-butanol for its radical inhibition effect. Furthermore, humic substances enhanced the reaction to some extent, but a slight negative effect would be encountered if the optimum dosage was exceeded. As a matter of fact, Mn（Ⅱ） affected the ozonation by ＂active sites＂ mechanism. In the experiment, three different kinds of intermediate products were produced during ozonation, but the amount of products for each one of them decreased as pH, temperature, ionic strength and initial ozone dosage increased. A kinetic equation of the reaction between ozone and DBP was obtained.展开更多
Nanometer zinc oxide （ZnO） powders were used as a catalyst to enhance the ozonation for the degradation of dichloroacetic acid （DCAA） in aqueous solution. The batch experiments were carded out to investigate the e...Nanometer zinc oxide （ZnO） powders were used as a catalyst to enhance the ozonation for the degradation of dichloroacetic acid （DCAA） in aqueous solution. The batch experiments were carded out to investigate the effects of key factors such as catalyst dosage, ozone dosage, solution pH and tert-butyl alcohol （t-BuOH） on the degradation efficiency of DCAA. Density functional theory （DFT） was adopted to explore the mechanism of generating hydroxyl radical （＇OH） on the ZnO surface. The results showed that adsorption and ozonation processes were not effective for DCAA removal, and the addition of ZnO catalyst improved the degradation efficiency of DCAA during ozonation, which caused an increase of 22.8% for DCAA decomposition compared to the case of ozonation alone after 25 min. Under the same experimental conditions, the DCAA decomposition was enhanced by increasing catalyst dosage from 100 to 500 mg/L and ozone dosage from 0.83 to 3.2 mg/L. The catalytic ozonation process is more pronounced than the ozonation process alone at pH 3.93, 6.88, and 10. With increasing the concentration of t-BuOH from 10 to 200 rag/L, the degradation of DCAA was significantly inhibited in the process of catalytic ozonation, indicating that ZnO catalytic ozonation followed ＂OH reaction mechanism. Based on the experimental results and DFT analysis, it is deduced that the generation of ＂OH on the ZnO surface is ascribed to the adsorption of molecule ozone followed by the interaction of adsorbed ozone with active sites of the catalyst surface. It is also concluded that ZnO may be an effective catalyst for DCAA removal, which could promote the formation of .OH derived from the catalytic decomposition of ozone.展开更多
Comparative studies of ozonation alone, ceramic honeycomb-catalyzed and Mn-Fe-K modified ceramic honeycomb catalyzed ozonation processes have been undertaken with benzophenone as the model organic pollutant. The exper...Comparative studies of ozonation alone, ceramic honeycomb-catalyzed and Mn-Fe-K modified ceramic honeycomb catalyzed ozonation processes have been undertaken with benzophenone as the model organic pollutant. The experimental results showed that the presence of Mn-Fe-K modified ceramic honeycombs significantly increased the removal rate of benzophenone and TOC compared with that achieved by ozonation alone or ceramic honeycomb-catalyzed ozonation. The electron paramagnetic resonance （EPR） experiments verified that higher benzophenone removal rate was attribute to more hydroxyl radicals generated in the Mn-Fe-K modified ceramic honeycomb-catalyzed ozonation. Under the conditions of this experiment, the degradation rate of all the three ozonation processes are increasing with the amount of catalyst, temperature and value of pH increased in the solution. We also investigated the effects of different process of ozone addition, the optimum conditions for preparing catalyst and influence of the Mn-Fe-K modified ceramic honeycomb after multiple-repeated use.展开更多
Endocrine disrupting chemicals(EDCs) in the secondary effluent discharged from wastewater treatment plants are of great concern when water reuse is intended. Ozonation and ultrafiltration(UF) are powerful technologies...Endocrine disrupting chemicals(EDCs) in the secondary effluent discharged from wastewater treatment plants are of great concern when water reuse is intended. Ozonation and ultrafiltration(UF) are powerful technologies reported to eliminate EDCs. Due to the importance of effluent organic matters(EfOMs) in secondary effluent, the effects of three kinds of EfOM on the treatment of five EDCs using ozonation and UF were investigated. The three kinds of EfOM studied were humic acid sodium salt(NaAH), bovine serum albumin(BSA)and sodium alginate(NaAg); and the five EDCs were estrone, 17β-estradiol, estriol, 17α-ethynyl estradiol and bisphenol A. The results showed that EfOM accelerated the decay rate of ozone and inhibited the degradation efficiency of EDCs by ozonation in the order NaAH > BSA > NaAg.The ultraviolet absorbance at 280 nm(UVA_(280)) has potential for use as a surrogate indicator to assess EDC removal via ozonation without conducting difficult EDC analyses. When the decline in UVA_(280) exceeded 18%, the five EDCs had been completely removed. The UF behavior of NaAH,BSA and NaAg was found to follow the cake filtration law. The fouling potential of EfOM followed the order NaAg > NaAH > BSA; while EfOM on the membrane surface enhanced EDC removal in the order NaAH > BSA > NaAg. The mean retention rate of the membrane was increased by 24%, 10% and 8%, respectively. The properties of EDCs and EfOM cakes both influenced the EDC removal rates due to adsorption, size exclusion and charge attraction.展开更多
The increasing amount of cyanided tailings produced as a by-product has gained significant attention in recent years because of the rapid development of the gold industry and extensive exploitation of gold mineral res...The increasing amount of cyanided tailings produced as a by-product has gained significant attention in recent years because of the rapid development of the gold industry and extensive exploitation of gold mineral resources. The effective use of these secondary resources is becoming an important and urgent problem for all environmental protection staff. Manganese-catalyzed ozonation for the pre-oxidation of cyanided tailings was studied and the effects of Mn2＋dosage, initial sulfuric acid concentration, ozone volume flow, temperature and agitation speed on pretreatment were examined. The optimum reaction conditions were observed to be： ore pulp density 2.5%, agitation speed 700 r/min,temperature 60°C, Mn2＋dosage 40 g/L, ozone volume flow 80 L/hr, initial sulfuric acid concentration 1 mol/L, and reaction time 6 hr. Under these conditions, the leaching rate of Fe and weight loss could reach 94.85% and 48.89% respectively. The leaching process of cyanided tailings by Mn2＋/O3 was analyzed, and it was found that the leaching of pyrite depends on synergetic oxidation by high-valent manganese and O3, in which the former played an important part.展开更多
Enhanced ozonation degradation of atrazine（ATZ） with nano-ZnO（nZnO） as catalyst and the influences of the operational parameters have been investigated through semi-continuous experiments in this study. The result...Enhanced ozonation degradation of atrazine（ATZ） with nano-ZnO（nZnO） as catalyst and the influences of the operational parameters have been investigated through semi-continuous experiments in this study. The results demonstrated that the combination of ozone（O3） and nZnO showed an obvious synergetic effect and the ATZ degradation conformed to pseudo-first-order kinetics. An improvement of ATZ degradation efficiency by 41.8% and pseudo-first-order rate constant by more than a factor of four was obtained in the O3/nZnO process after 5 min of reaction compared to O3 alone. Meanwhile, the degradation efficiency of ATZ was gradually enhanced with increasing nZnO dosage and initial pH in the range from 3.0 to 8.0, and a higher amount of ATZ was degraded when the initial concentration of ATZ rose from 0.5 to 5 mg/L. Additionally, sulfate ion, chloride ion, nitrate ion and low concentrations of humic acid substances led to enhancement of the ATZ degradation. The notable decrease of ATZ removal efficiency observed in the presence of radical scavengers and the results of free radical tests indicated thatUOH is the dominant active radical species. The mechanism investigation demonstrated that the enhancement effect could be attributed to the introduction of nZnO,which could promote the utilization of O3, enhance the formation of superoxide radical, and further accelerate the production of hydrogen peroxide and the generation of OH/O2-.展开更多
Mesoporous MCM-41 and Fe loaded MCM-41（Fe/MCM-41）,which were successfully prepared by a hydrothermal method and a dipping method respectively,were applied as heterogeneous catalysts for ozonation of p-chlorobenzoic ...Mesoporous MCM-41 and Fe loaded MCM-41（Fe/MCM-41）,which were successfully prepared by a hydrothermal method and a dipping method respectively,were applied as heterogeneous catalysts for ozonation of p-chlorobenzoic acid（p-CBA） in aqueous solution.MCM-41 and Fe/MCM-41 were characterized by XRD,FT-IR and diffuse reflectance UV-vis（DR-UV-vis） techniques. The presence of either MCM-41 or Fe/MCM-41 improves p-CBA and total organic carbon（TOC） removal efficiency compared to ozonation alone.Under the experimental condition,TOC removal rate of Fe/MCM-41/O_3 process is over 63.5%at 60 min oxidation time,44.5%using MCM-41 as catalyst,only 37.7%with ozonation alone.The presence of tert-butanol（TBA） in the Fe/MCM-41/ O_3 process indicated that the oxidation mechanism of p-CBA occurs via OH in the liquid bulk.And Fe/MCM-41 is a promising catalyst.展开更多
Endocrine disrupting chemicals（EDCs） in the secondary effluent discharged from wastewater treatment plants（WWTPs） are of great concern in the process of water reuse.Ozonation has been reported as a powerful oxidat...Endocrine disrupting chemicals（EDCs） in the secondary effluent discharged from wastewater treatment plants（WWTPs） are of great concern in the process of water reuse.Ozonation has been reported as a powerful oxidation technology to eliminate micropollutants in water treatment.Due to the complexity of the wastewater matrix,orthogonal experiments and single factor experiments were conducted to study the influence of operational parameters on the degradation of 17α-ethinylestradiol（EE2） in the synthetic secondary effluent.The results of the orthogonal experiments indicated that the initial ozone and natural organic matter（NOM） concentration significantly affected EE2 degradation efficiency,which was further validated by the single factor confirmation experiments.EE2 was shown to be effectively degraded by ozonation in the conditions of low pH（6）,NOM（10 mg/L）,carbonate（50 mg/L）,but high suspended solid（20 mg/L） and initial ozone concentration（9 mg/L）.The study firstly revealed that the lower pH resulted in higher degradation of EE2 in the synthetic secondary effluent,which differed from EDCs ozonation behavior in pure water.EE2 degradation by ozone molecule instead of hydroxyl radical was proposed to play a key role in the degradation of EDCs by ozonation in the secondary effluent.The ratio between O3 and TOC was identified as an appropriate index to assess the degradation of EE2 by ozonation in the synthetic secondary effluent.展开更多
基金supported by the National Natural Science Foundation of China(No.22206013).
文摘The efficient mineralization of phenol and its derivatives in wastewater remains a great challenge.In this study,the bimetallic CuCeO_(2)-BTC was screened from a series of MOFs-derived MCeO_(2)-BTC(M=La,Cu,Co,Fe,and Mn)catalysts,and the influence of the Cu/Ce ratio on phenol removal by catalytic ozonation was carefully examined.The results indicate that Cu_(2)Ce_(1)O_(y)-BTC was the best among the Cu_(x)Ce_(1)O_(y)-BTC(x=0,1,2,and 3)catalysts,with a phenol mineralization efficiency reaching close to 100%within 200 min,approximately 30.1%higher than CeO_(2)-BTC/O_(3)and 70.3%higher than O_(3)alone.The order of mineralization efficiency of phenol was Cu_(2)Ce_(1)O_(y)-BTC>Cu_(3)Ce_(1)O_(y)-BTC>Cu_(1)Ce_(1)O_(y)-BTC>CeO_(2)-BTC.CeO_(2)-BTC exhibited a broccoli-like morphology,and Cu_(x)Ce_(1)O_(y)-BTC(x=1,2,and 3)exhibited an urchin-like morphology.Compared with Cu_(x)Ce_(1)O_(y)-BTC(x=0,1,and 3),Cu_(2)Ce_(1)O_(y)-BTC exhibited a larger specific surface area and pore volume.This characteristic contributed to the availability of more active sites for phenol degradation.The redox ability was greatly enhanced as well.Besides,the surface of Cu_(2)Ce_(1)O_(y)-BTC exhibited a higher concentration of Ce^(3+)species and hydroxyl groups,which facilitated the dissociation of ozone and the generation of active radicals.Based on the results of radical quenching experiments and the intermediates detected by LC-MS,a potential mechanism for phenol degradation in the Cu_(2)Ce_(1)O_(y)-BTC/O_(3)system was postulated.This study offers novel perspectives on the advancement of MOFs-derived catalysts for achieving the complete mineralization of phenol in wastewater through catalytic ozonation.
基金Project(2022M710619)supported by the Postdoctoral Science Foundation of ChinaProjects(2020YFH0213,2020YFG0039)supported by the Sichuan Science and Technology Program,China+1 种基金Projects(XJ2024001501,KCXTD2023-4)supported by the Basic Scientific Foundation and Innovation Team Funds of China West Normal UniversityProject(CSPC202403)supported by the Open Project Program of Chemical Synthesis and Pollution Control Key Laboratory of Sichuan Province,China。
文摘In response to the fact that the presence of manganese dithionate(MnS_(2)O_(6))leads to a series of adverse impacts,especially lower purity of manganese sulfate(MnSO_(4))and disruption of its recovery,advanced oxidation methods such as ozonation system are used to manage MnS_(2)O_(6)in the leaching solution,replacing conventional methods.To ascertain the conversion rate and kinetics of MnS_(2)O_(6)during the ozonation process,we explored the factors influencing its removal rate,including ozone dosage,manganese dithionate concentration,sulfuric acid concentration,and reaction temperature.Batch experiments were conducted to determine the reaction rate constant of ozone(k)and activation energy(Ea)obtained from intermittent experimental data fitting,revealing a least-squares exponential conversion relationship between k and the MnS_(2)O_(6)removal amount,wherein an increase in the aforementioned factors led to an enhanced MnS_(2)O_(6)conversion rate,exceeding 99.3%.The formation mechanism of the ozone products proposed during the experiment was summarized and proposed as follows:1)Mn^(2+)was directly oxidized to MnO_(2),and 2)SO_(4)2−was obtained by the catalytic oxidation of S_(2)O_(6)^(2−)with HO•from O3 decomposition.According to the kinetics analysis,the pre-exponential factor and total activation energy of the ozonation kinetics equation were 1.0×10^(23) s^(−1) and 177.28 kJ/mol,respectively.Overall,the present study demonstrates that O_(3) as an oxidizing agent can effectively facilitate MnS_(2)O_(6)disproportionation while preventing the release of the secondary pollutant,SO_(2)gas.
基金supported by the National Natural Science Foundation of China(Nos.52270073 and 51708292)。
文摘This study aims to identify the highly non-specific toxic by-products during ozonation of three cresols in wastewater.In ozonated effluents,biotoxicity increased along with increasing reaction time,followed by a gradual decrease.The peak biotoxicity for ozonated o-cresol(o-C),m-cresol(m-C),and p-cresol(p-C)was estimated to be 17.4,14.8 and 5.5 times higher than that of untreated wastewater,respectively.A redox-directed approach with high-resolution mass spectrometry detection and toxicity prediction revealed that monomeric para-benzoquinones(p-BQs),hydroxylated p-BQs,and dimeric p-BQs in ozonated cresols were the primary contributors to the increased toxicity.Calculations based on density functional theory indicated formation pathways of p-BQs byproducts,e.g.,the formation of 2-methyl-p-benzoquinone was likely induced by ozone molecules rather than hydroxyl radicals in ozonated o-C and m-C,and the formation of p-BQs during ozonation of p-C was attributed to the oxidation of methyl group to carboxyl group and subsequent decarboxylation initiated by hydroxyl radicals.Electron paramagnetic resonance and spin density calculation showed that the presence of carbon-centered cresoxyl radicals was responsible for dimeric p-BQs formation.Collectively,these results underscore significant contribution of non-halogenated p-BQs to non-specific toxicity increase in ozonated effluents.
文摘Photocatalytic ozonation holds promise for advanced water purification,yet its development has been hindered by a limited understanding of ozone activation mechanisms and its related photogenerated electron transfer dynamics.Herein,we employed in-situ DRIFTS and Raman spectroscopy to elucidate the distinct adsorption and activation behaviors of ozone(O_(3))on the{001}and{110}crystal facets of Bi_(2)O_(2)CO_(3)(BOC)nanosheets.BOC-{001}demonstrates superior photocatalytic ozonation performance,with 85%phenol mineralization and excellent durability,significantly outperforming the 53%mineralization rate of BOC-{110}.This enhanced activity is attributed to non-dissociative ozone adsorption and favorable adsorption energy over{001}facet,which facilitate the one-electron O_(3) reduction pathway.Furthermore,crystal facet engineering strengthens the built-in electric field,promoting exciton dissociation and the generation of localized charge carriers.The synergistic effects of optimized electron availability and ozone adsorption significantly boost the production of reactive oxygen species.These findings provide a deeper understanding of the critical roles of O_(3) adsorption and electron transfer in radical generation,which could provide some guidance for the strategic development of highly effective photocatalytic ozonation catalysts.
基金supported by the National Key Research and Development Program of China(No.2016YFC0207100).
文摘Nowadays,it is still a challenge to prepared high efficiency and low cost formaldehyde(HCHO)removal catalysts in order to tackle the long-living indoor air pollution.Herein,δ-MnO_(2)is successfully synthesized by a facile ozonation strategy,where Mn^(2+)is oxidized by ozone(O_(3))bubble in an alkaline solution.It presents one of the best catalytic properties with a low 100%conversion temperature of 85℃for 50 ppm of HCHO under a GHSV of 48,000 mL/(g·hr).As a comparison,more than 6 times far longer oxidation time is needed if O3 is replaced by O_(2).Characterizations show that ozonation process generates a different intermediate of tetragonalβ-HMnO_(2),which would favor the quick transformation into the final productδ-MnO_(2),as compared with the relatively more thermodynamically stable monoclinicγ-HMnO_(2)in the O_(2)process.Finally,HCHO is found to be decomposed into CO_(2)via formate,dioxymethylene and carbonate species as identified by room temperature insitu diffuse reflectance infrared fourier transform spectroscopy.All these results show great potency of this facile ozonation routine for the highly activeδ-MnO_(2)synthesis in order to remove the HCHO contamination.
文摘To convert the non biodegradable sodium lignin sulfonate into biodegradable substances, the sodium lignin sulfonate in the water was ozonized and the pH value, dissolved organic carbon(DOC), ultraviolet absorbency at λ =254 nm(UVA) and the biodegradability of the ozonation effluent were measured. The non biodegradable sodium lignin sulfonate can be partly converted into biodegradable substances by ozonation (about 38 76%). In the ozonation process, there is little DOC decrease, but much UVA decrease and obvious pH drop.
文摘A study on advanced drinking water treatment was conducted in a pilot scale plant taking water from conventional treatment process. Ozonation-biological activated carbon process （O3-BAC） and granular activated carbon process （GAC） were evaluated based on the following parameters： CODMn, UV254, total organic carbon （TOC）, assimilable organic carbon （AOC） and biodegradable dissolved organic carbon （BDOC）. In this test, the average removal rates of CODMn, UV254 and TOC in O3-BAC were 18.2%, 9.0% and 10.2% higher on （AOC） than in GAC, respectively. Ozonation increased 19.3-57.6 μg Acetate-C/L in AOC-P17, 45.6-130.6 μg Acetate-C/L in AOC-NOX and 0.1-0.5 mg/L in BDOC with ozone doses of 2 8 mg/L. The optimum ozone dose for maximum AOC formation was 3 mgO3/L. BAC filtration was effective process to improve biostability.
文摘The degradation mechanism of Cationic Red X-GRL was investigated when the intermediates, the nitrate ion and the pH were analyzed in the ozonation. The degradation of the Cationic Red X-GRL includes the de-auxochrome stage, the decolour stage, and the decomposition of fragment stage. During the degradation process, among the six nitrogen atoms of Cationic Red X-GRL, one is transferred into a nitrate ion, one becomes the form of an amine compound, and the rest four are transformed into two molecules of nitrogen. In the course of the ozonation of Cationic Red X-GRL, the direct attack of ozone is the main decolour effect.
基金Supported by the National Nanotechnology Center(NANOTEC)(601003)the National Science and Technology Development Agency(NSTDA)
文摘A three phase fluidized bed reactor was used to investigate the combined effect of adsorption and oxidation for phenolic wastewater treatment.Aqueous solutions containing 10 mg·L 1of phenol and ozone were continuously fed co-currently as upward flow into the reactor at constant flow rate of 2 and 1 L·min 1,respectively.The phenolic treatment results in seven cases were compared：（a）O3 only,（b）fresh granular activated carbon（GAC）,（c） 1st reused GAC,（d）2nd reused GAC,（e）fresh GAC enhanced with O3,（f）1st reused GAC enhanced with O3,and （g）2nd reused GAC enhanced with O3.The phenolic wastewater was re-circulated through the reactor and its concentration was measured with respect to time.The experimental results revealed that the phenolic degradation using GAC enhanced with O3 provided the best result.The effect of adsorption by activated carbon was stronger than the effect of oxidation by ozone.Fresh GAC could adsorb phenol better than reused GAC.All cases of adsorption on GAC followed the Langmuir isotherm and displayed pseudo second order adsorption kinetics.Finally,a differential equation for the fluidized bed reactor model was used to describe the phenol concentration with respect to time for GAC enhanced with O3.The calculated results agree reasonably well with the experimental results.
基金supported by National Key R&D Program of China(No.2018YFC0406300)the operation for central university of Hohai University(No.2013/B18020148)A Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions。
文摘The catalytic ozonation treatment of secondary biochemical effluent for papermaking wastewater by Ag-doped nickel ferrite was investigated.Ag-doped catalysts prepared by sol-gel method were characterized,illustrating that Ag entirely entered the crystalline of Ni Fe2O4 and changed the surface properties.The addition of catalyst enhanced the removal efficiency of chemical oxygen demand and total organic carbon.The results of gas chromatography-mass spectrometer,ultraviolet light absorbance at 254 nm and threedimensional fluorescence excitation-emission matrix suggested that aromatic compounds were efficiently degraded and toxic substances,such as dibutyl phthalate.In addition,the radical scavenging experiments confirmed the hydroxyl radicals acted as the main reactive oxygen species and the surface properties of catalysts played an important role in the reaction.Overall,this work validated potential applications of Ag-doped Ni Fe2O4 catalyzed ozonation process of biologically recalcitrant wastewater.
基金supported by the National Natural Science Foundation of China(No.50578146,20876151)the National Science Foundation of Zhejiang Province,China(No.Y5080178)
文摘Fe3O4-CoO/Al2O3 catalyst was prepared by incipient wetness impregnation using Fe（NO3）3.9H2O and Co（NO3）2.6H2O as the precursors, and its catalytic performance was investigated in ozonation of 2-（2,4-dichlorophenoxy）propionic acid （2,4-DP）, nitrobenzene and oxalic acid. The experimental results indicated that Fe3O4-CoO/Al2O3 catalyst enabled an interesting improvement of ozonation efficiency during the degradation of each organic pollutant, and the Fe3O4-CoO/Al2O3 catalytic ozonation system followed a radical-type mechanism. The kinetics of ozonation alone and Fe3O4-CoO/Al2O3 catalytic ozonation of three organic pollutants in aqueous solution were discussed under the mere consideration of direct ozone reaction and OH radical reaction to well investigate its performance. In the catalytic ozonation of 2,4-DP, the apparent reaction rate constants （k） were determined to be 1.456 × 10^-2 min-1 for ozonation alone and 4.740 × 10^-2 min^-1 for O3/Fe3O4-CoO/Al2O3. And O3/Fe3O4-CoO/Al2O3 had a larger Rot （6.614 × 10^-9） calculated by the relative method than O3 did （1.800 x 10-9）, showing O3/Fe3O4-CoO/Al2O3 generated more hydroxyl radical. Similar results were also obtained in the catalytic ozonation of nitrobenzene and oxalic acid. The above results demonstrated that the catalytic performance of Fe3O4-CoO/Al2O3 in ozonation of studied organic substance was universal to a certain degree.
基金Project(40973074) supported by the National Natural Science Foundation of China
文摘A novel heterogeneous catalytic ozonation process in water treatment was studied, with a copper-loaded activated carbon （Cu/AC） that was prepared by an incipient wetness impregnation method at low temperature and tested as a catalyst in the ozonation of phenol and oxalic acid. Cu/AC was characterized using XRD, BET and SEM techniques. Compared with ozonation alone, the presence of Cu/AC in the ozonation processes significantly improves the degradation of phenol or oxalic acid. With the introduction of the hydroxyl radical scavenger, i.e., turt-butanol alcohol （t-BuOH）, the degradation efficiency of both phenol and oxalic acid in the Cu/AC catalyzed ozonation process decreases by 22% at 30 min. This indicates that Cu/AC accelerates ozone decomposition into certain concentration of hydroxyl radicals. The amount of Cu（II ） produced during the reaction of Cu/AC-catalyzed ozonation of phenol or oxalic acid is very small, which shows that the two processes are both heterogeneous catalytic ozonation reactions.
基金The National Science Fund for Distinguished Young Scholars (No. 50225824), the National Natural Science Foundation of China(No. 50538090) and the Beijing Academic Innovation Group in Sustainable Water/Waste Recycle Technologies (No. BJE10016200611)
文摘Ozonation of synthetic water containing a type of endocrine disruptor-di-n-butyl phthalate （DBP） was examined. Key impact factors such as pH, temperature, ionic strength, ozone dosage and initial DBP concentration were investigated. In addition, the activities of radicals on uncatalysed and catalysed ozonation were studied. The degradation intermediate products were followed and the kinetic of the ozonation were assessed as well. Results revealed that ozonation of DBP followed two mechanisms. Firstly, the reaction rate of direct ozonation was slower at lower pH, temperature, and ionic strength. Secondly, when these factors were increased for indirect radical reaction, higher percentage of DBP was removed with the increase of the initial ozone dosage and the decrease of the initial DBP concentration. In addition, tea-butanol, humic substances and Fe（Ⅱ） affected DBP ozonation through the radical pathway. It was determined that ozonation was restrained by adding tea-butanol for its radical inhibition effect. Furthermore, humic substances enhanced the reaction to some extent, but a slight negative effect would be encountered if the optimum dosage was exceeded. As a matter of fact, Mn（Ⅱ） affected the ozonation by ＂active sites＂ mechanism. In the experiment, three different kinds of intermediate products were produced during ozonation, but the amount of products for each one of them decreased as pH, temperature, ionic strength and initial ozone dosage increased. A kinetic equation of the reaction between ozone and DBP was obtained.
基金support by the National Natural Science Foundation of China(No.50638020)the High Technology Research and Development Program(863)of China (No.2007AA06Z339)+1 种基金the National Important Science and Technology Specific Project for the Control and Treatment of Water Pollution(No.2009ZX07424-004)the National Key Technology R&D Program during the 11th Five-Year Plan Period(No.2006BAJ08B02)
文摘Nanometer zinc oxide （ZnO） powders were used as a catalyst to enhance the ozonation for the degradation of dichloroacetic acid （DCAA） in aqueous solution. The batch experiments were carded out to investigate the effects of key factors such as catalyst dosage, ozone dosage, solution pH and tert-butyl alcohol （t-BuOH） on the degradation efficiency of DCAA. Density functional theory （DFT） was adopted to explore the mechanism of generating hydroxyl radical （＇OH） on the ZnO surface. The results showed that adsorption and ozonation processes were not effective for DCAA removal, and the addition of ZnO catalyst improved the degradation efficiency of DCAA during ozonation, which caused an increase of 22.8% for DCAA decomposition compared to the case of ozonation alone after 25 min. Under the same experimental conditions, the DCAA decomposition was enhanced by increasing catalyst dosage from 100 to 500 mg/L and ozone dosage from 0.83 to 3.2 mg/L. The catalytic ozonation process is more pronounced than the ozonation process alone at pH 3.93, 6.88, and 10. With increasing the concentration of t-BuOH from 10 to 200 rag/L, the degradation of DCAA was significantly inhibited in the process of catalytic ozonation, indicating that ZnO catalytic ozonation followed ＂OH reaction mechanism. Based on the experimental results and DFT analysis, it is deduced that the generation of ＂OH on the ZnO surface is ascribed to the adsorption of molecule ozone followed by the interaction of adsorbed ozone with active sites of the catalyst surface. It is also concluded that ZnO may be an effective catalyst for DCAA removal, which could promote the formation of .OH derived from the catalytic decomposition of ozone.
基金The National Natural Science Foundation of China (No. 50378028)
文摘Comparative studies of ozonation alone, ceramic honeycomb-catalyzed and Mn-Fe-K modified ceramic honeycomb catalyzed ozonation processes have been undertaken with benzophenone as the model organic pollutant. The experimental results showed that the presence of Mn-Fe-K modified ceramic honeycombs significantly increased the removal rate of benzophenone and TOC compared with that achieved by ozonation alone or ceramic honeycomb-catalyzed ozonation. The electron paramagnetic resonance （EPR） experiments verified that higher benzophenone removal rate was attribute to more hydroxyl radicals generated in the Mn-Fe-K modified ceramic honeycomb-catalyzed ozonation. Under the conditions of this experiment, the degradation rate of all the three ozonation processes are increasing with the amount of catalyst, temperature and value of pH increased in the solution. We also investigated the effects of different process of ozone addition, the optimum conditions for preparing catalyst and influence of the Mn-Fe-K modified ceramic honeycomb after multiple-repeated use.
基金supported by the National Natural Science Foundation of China (No.51808008)the Natural Science Foundation of Hebei Province (No.E2017409004)the Youth Foundation of Hebei Province Education Department (No.QN2016224)
文摘Endocrine disrupting chemicals(EDCs) in the secondary effluent discharged from wastewater treatment plants are of great concern when water reuse is intended. Ozonation and ultrafiltration(UF) are powerful technologies reported to eliminate EDCs. Due to the importance of effluent organic matters(EfOMs) in secondary effluent, the effects of three kinds of EfOM on the treatment of five EDCs using ozonation and UF were investigated. The three kinds of EfOM studied were humic acid sodium salt(NaAH), bovine serum albumin(BSA)and sodium alginate(NaAg); and the five EDCs were estrone, 17β-estradiol, estriol, 17α-ethynyl estradiol and bisphenol A. The results showed that EfOM accelerated the decay rate of ozone and inhibited the degradation efficiency of EDCs by ozonation in the order NaAH > BSA > NaAg.The ultraviolet absorbance at 280 nm(UVA_(280)) has potential for use as a surrogate indicator to assess EDC removal via ozonation without conducting difficult EDC analyses. When the decline in UVA_(280) exceeded 18%, the five EDCs had been completely removed. The UF behavior of NaAH,BSA and NaAg was found to follow the cake filtration law. The fouling potential of EfOM followed the order NaAg > NaAH > BSA; while EfOM on the membrane surface enhanced EDC removal in the order NaAH > BSA > NaAg. The mean retention rate of the membrane was increased by 24%, 10% and 8%, respectively. The properties of EDCs and EfOM cakes both influenced the EDC removal rates due to adsorption, size exclusion and charge attraction.
基金supported by the Innovation Foundation of Donghua University for Doctoral Candidates (No. BC201132)the Shanghai Leading Academic Discipline Project (No. B604)
文摘The increasing amount of cyanided tailings produced as a by-product has gained significant attention in recent years because of the rapid development of the gold industry and extensive exploitation of gold mineral resources. The effective use of these secondary resources is becoming an important and urgent problem for all environmental protection staff. Manganese-catalyzed ozonation for the pre-oxidation of cyanided tailings was studied and the effects of Mn2＋dosage, initial sulfuric acid concentration, ozone volume flow, temperature and agitation speed on pretreatment were examined. The optimum reaction conditions were observed to be： ore pulp density 2.5%, agitation speed 700 r/min,temperature 60°C, Mn2＋dosage 40 g/L, ozone volume flow 80 L/hr, initial sulfuric acid concentration 1 mol/L, and reaction time 6 hr. Under these conditions, the leaching rate of Fe and weight loss could reach 94.85% and 48.89% respectively. The leaching process of cyanided tailings by Mn2＋/O3 was analyzed, and it was found that the leaching of pyrite depends on synergetic oxidation by high-valent manganese and O3, in which the former played an important part.
基金supported by the state supported project funds for researchdemonstration on the key technology for clean production in textile printing and dyeing (2014BAC13B02)
文摘Enhanced ozonation degradation of atrazine（ATZ） with nano-ZnO（nZnO） as catalyst and the influences of the operational parameters have been investigated through semi-continuous experiments in this study. The results demonstrated that the combination of ozone（O3） and nZnO showed an obvious synergetic effect and the ATZ degradation conformed to pseudo-first-order kinetics. An improvement of ATZ degradation efficiency by 41.8% and pseudo-first-order rate constant by more than a factor of four was obtained in the O3/nZnO process after 5 min of reaction compared to O3 alone. Meanwhile, the degradation efficiency of ATZ was gradually enhanced with increasing nZnO dosage and initial pH in the range from 3.0 to 8.0, and a higher amount of ATZ was degraded when the initial concentration of ATZ rose from 0.5 to 5 mg/L. Additionally, sulfate ion, chloride ion, nitrate ion and low concentrations of humic acid substances led to enhancement of the ATZ degradation. The notable decrease of ATZ removal efficiency observed in the presence of radical scavengers and the results of free radical tests indicated thatUOH is the dominant active radical species. The mechanism investigation demonstrated that the enhancement effect could be attributed to the introduction of nZnO,which could promote the utilization of O3, enhance the formation of superoxide radical, and further accelerate the production of hydrogen peroxide and the generation of OH/O2-.
基金the financial support from National Natural Science Foundation of China (No.20977036)
文摘Mesoporous MCM-41 and Fe loaded MCM-41（Fe/MCM-41）,which were successfully prepared by a hydrothermal method and a dipping method respectively,were applied as heterogeneous catalysts for ozonation of p-chlorobenzoic acid（p-CBA） in aqueous solution.MCM-41 and Fe/MCM-41 were characterized by XRD,FT-IR and diffuse reflectance UV-vis（DR-UV-vis） techniques. The presence of either MCM-41 or Fe/MCM-41 improves p-CBA and total organic carbon（TOC） removal efficiency compared to ozonation alone.Under the experimental condition,TOC removal rate of Fe/MCM-41/O_3 process is over 63.5%at 60 min oxidation time,44.5%using MCM-41 as catalyst,only 37.7%with ozonation alone.The presence of tert-butanol（TBA） in the Fe/MCM-41/ O_3 process indicated that the oxidation mechanism of p-CBA occurs via OH in the liquid bulk.And Fe/MCM-41 is a promising catalyst.
基金supported by the National High Technology Research and Development Program (863) of China (No.2008AA062502)
文摘Endocrine disrupting chemicals（EDCs） in the secondary effluent discharged from wastewater treatment plants（WWTPs） are of great concern in the process of water reuse.Ozonation has been reported as a powerful oxidation technology to eliminate micropollutants in water treatment.Due to the complexity of the wastewater matrix,orthogonal experiments and single factor experiments were conducted to study the influence of operational parameters on the degradation of 17α-ethinylestradiol（EE2） in the synthetic secondary effluent.The results of the orthogonal experiments indicated that the initial ozone and natural organic matter（NOM） concentration significantly affected EE2 degradation efficiency,which was further validated by the single factor confirmation experiments.EE2 was shown to be effectively degraded by ozonation in the conditions of low pH（6）,NOM（10 mg/L）,carbonate（50 mg/L）,but high suspended solid（20 mg/L） and initial ozone concentration（9 mg/L）.The study firstly revealed that the lower pH resulted in higher degradation of EE2 in the synthetic secondary effluent,which differed from EDCs ozonation behavior in pure water.EE2 degradation by ozone molecule instead of hydroxyl radical was proposed to play a key role in the degradation of EDCs by ozonation in the secondary effluent.The ratio between O3 and TOC was identified as an appropriate index to assess the degradation of EE2 by ozonation in the synthetic secondary effluent.
