Studies widely acknowledge the enhancement of permanganate(Mn(Ⅶ))oxidation of organic contaminants by coexisting matrices in water.This study investigated the positive influence of Mn(Ⅱ),a common soluble metal ion,o...Studies widely acknowledge the enhancement of permanganate(Mn(Ⅶ))oxidation of organic contaminants by coexisting matrices in water.This study investigated the positive influence of Mn(Ⅱ),a common soluble metal ion,on the removal of trace organic pollutants by Mn(Ⅶ).Results showed that introducing 20μmol/L Mn(Ⅱ)at pH 5.0 accelerated trace organic pollutant removal by promoting colloidal MnO_(2)formation.UV-vis spectrum,quenching,and probe experiments confirmed role of MnO_(2)in sulfamethoxazole(SMX)oxidation,with Mn(Ⅲ)playing a predominant role.Meanwhile,in situ-generated MnO_(2)facilitated Mn(Ⅶ)*formation,enhancing oxidation performance,as indicated by Raman spectroscopy and electrochemical analysis.Eleven transformation products(TPs)of SMX in the Mn(Ⅶ)/Mn(Ⅱ)process were detected by UPLC-QTOF-MS/MS.Subsequently,the reaction pathways of SMX were elucidated through Fukui index analysis and the identification of TPs.Additionally,toxicity simulations with Toxicity Estimation Software Tool(T.E.S.T.)software revealed significantly lower cytotoxicity of TPs of SMX compared to the parent compound.This study unveils an effective strategy to enhance Mn(Ⅶ)-mediated degradation of organic pollutants in water,elucidating Mn(Ⅱ)-induced Mn(Ⅶ)activation mechanisms.展开更多
Using the glucose and L-glutamic-acid to prepare the standard substance according to the ratio of 1：1, and the artificial seawater and the standard substance to prepare a series of standard solutions, the distributio...Using the glucose and L-glutamic-acid to prepare the standard substance according to the ratio of 1：1, and the artificial seawater and the standard substance to prepare a series of standard solutions, the distribution pattern of uncertainty in measurement of seawater COD is obtained based on the measured results of the series of standard solutions by the potassium iodide-alkaline potassium permanganate determination method. The distribution pattern is as follows： Uncertainty in measurement is big and not constant at the high end, but small and constant at the low end.展开更多
A novel chemiluminescence （CL） system for determination of permanganate index （CODMn） combined with flow injection analysis has been proposed in this study. On the basis of the chemiluminescent reaction of luminol...A novel chemiluminescence （CL） system for determination of permanganate index （CODMn） combined with flow injection analysis has been proposed in this study. On the basis of the chemiluminescent reaction of luminol-KMnO4 system, light emission caused by luminol-KMnO4 system was detected by the photomultiplier tube, and its intensity caused by the appearance of KMnO4 after sample digestion was inversely proportional to CODMn. Effects for CODMn determining such as pH, concentrations and interference were investigated in detail. A detection limit of 0.3 mg/L CODMn with a linear range of 0.3-200 mg/L for its theoretical CODMn was obtained under the optimized experimental conditions. The relative standard deviation was 4.3% for 5.0 mg/L CODMn （n = 11）. This CL flow system for determining CODMn was simple, rapid, and suitable for automatic analysis. The data obtained by the present method were fairly in good agreement with those obtained by the standard titrimetric method. It has been applied to determine real samples with satisfactory results.展开更多
The oxidation of As（Ⅲ） with potassium permanganate was studied under conditions including pH, initial As（Ⅲ） concentration and dosage of Mn（Ⅶ）. The results have shown that potassium permanganate was an effecti...The oxidation of As（Ⅲ） with potassium permanganate was studied under conditions including pH, initial As（Ⅲ） concentration and dosage of Mn（Ⅶ）. The results have shown that potassium permanganate was an effective agent for oxidation of As（Ⅲ） in a wide pH range. The pH value of tested water was not a significant factor affecting the oxidation of As（Ⅲ） by Mn（Ⅲ）. Although theoretical redox analyses suggest that Mn（Ⅶ） should have better performance in oxidization of As（Ⅲ） within lower pH ranges, the experimental results show that the oxidation efficiencies of As（Ⅲ） under basic and acidic conditions were similar, which may be due to the adsorption of As（Ⅲ） on the Mn（OH）2 and MnO2 resulting from the oxidation of As（Ⅲ）.展开更多
Summary： Traumatic gas gangrene is a fatal infection mainly caused by Clostridium perfringens. It is a challenge to manage gas gangrene in open wounds and control infection after debridement or amputa- tion. The aim ...Summary： Traumatic gas gangrene is a fatal infection mainly caused by Clostridium perfringens. It is a challenge to manage gas gangrene in open wounds and control infection after debridement or amputa- tion. The aim of the present study was to use vacuum sealing drainage （VSD） with continuous irrigation of potassium permanganate to manage infective wounds of gas gangrene and observe its clinical effi- cacy. A total of 48 patients with open traumatic gas gangrene infection were included in this study. Am- putations were done for 27 patients, and limb salvage procedures were performed for the others. After amputation or aggressive debridement, the VSD system, including polyvinyl alcohol （PVA） foam dress- ing and polyurethane （PU） film, with continuous irrigation of 1：5000 potassium permanganate solutions, was applied to the wounds. During the follow-up, all the patients healed without recurrence within 8-18 months. There were four complications. Cardiac arrest during amputation surgery occurred in one pa- tient who suffered from severe septic shock. Emergent resuscitation was performed and the patient re- turned to stable condition. One patient suffered from mixed infection of Staphylococcal aureus, and a second-stage debridement was performed. One patient suffered from severe pain of the limb after the debridement. Exploratory operation was done and the possible reason was trauma of a local peripheral nerve. Three cases of crush syndrome had dialysis treatment for concomitant renal failure. In conclusion, VSD can convert open wound to closed wound, and evacuate necrotic tissues. Furthermore, potassium permanganate solutions help eliminate anaerobic microenviroument and achieve good therapeutic effect on gas gangrene and mixed infection. VSD with continuous irrigation of potassium permanganate is a novel, simple and feasible alternative for severe traumatic open wounds with gas gangrene infection.展开更多
The adsorption characteristics of virgin and potassium permanganate modified lignite semi-coke （SC） for gaseous Hg were investigated in an attempt to produce more effective and lower price adsorbents for the control...The adsorption characteristics of virgin and potassium permanganate modified lignite semi-coke （SC） for gaseous Hg were investigated in an attempt to produce more effective and lower price adsorbents for the control of elemental mercury emission. Brunauer-Emmett- Teller （BET） measurements, X-ray powder diffraction （XRD） and X-ray photoelectron spectroscopy （XPS） were used to analyze the surface physical and chemical properties of SC, Mn-SC and Mn-H-SC before and after mercury adsorption. The results indicated that potassium permanganate modification had significant influence on the properties of semi-coke, such as the specific surface area, pore structure and surface chemical functional groups. The mercury adsorption efficiency of modified semi-coke was lower than that of SC at low temperature, but much higher at high temperature. Amorphous Mn7＋, Mn6＋ and Mn4＋ on the surface of Mn-SC and Mn-H-SC were the active sites for oxidation and adsorption of gaseous Hg~, which oxidized the elemental mercury into Hg2＋ and captured it. Thermal treatment reduced the average oxidation degree of Mn2＋ on the surface of Mn-SC from 3.80 to 3.46. However, due to the formation of amorphous MnOx, the surface oxidation active sites for gaseous Hg0 increased, which gave Mn-H-SC higher mercury adsorption efficiency than that of Mn-SC at high temperature.展开更多
Chlorine content and position of chlorinated phenols have many significant effects on the reactivity of oxido-reduction. The effects of chlorine content and position of chlorinated phenols on their oxidation kinetics ...Chlorine content and position of chlorinated phenols have many significant effects on the reactivity of oxido-reduction. The effects of chlorine content and position of chlorinated phenols on their oxidation kinetics by potassium permanganate were evaluated through different kinetics studies. Since chlorine was an electron withdrawing atom, the substitution of chlorine on the aromatic ring decreased the oxidation rate constant by σ-electron withdrawing conductive effect. The substitution of chlorine at ortho or para position on the aromatic ring increased the oxidation rate constant by π-electron donating conjugative effect, and the conjugative effect could counteract the negative impact of the conductive effect to some extent. On the other hand, the substitution of chlorine at ortho position on the aromatic ring decreased the oxidation rate constant by steric hindrance effect. The oxidation rate constants of phenol and chlorinated phenols studied decreased as follow order: 4-chlorophenol>2,4-dichlorophenol>phenol>2,6-dichlorophenol.展开更多
The effects of bisulfite-activated permanganate technology(PM/BS)as a pre-oxidation process on enhancing Microcystis aeruginosa(M.aeruginosa)removal by post coagulation were investigated.The results demonstrated that ...The effects of bisulfite-activated permanganate technology(PM/BS)as a pre-oxidation process on enhancing Microcystis aeruginosa(M.aeruginosa)removal by post coagulation were investigated.The results demonstrated that pretreatment with PM/BS process effectively promoted the algae removal by coagulation with Al2(SO4)3 as the coagulant and this phenomenon was more obvious with the increase of water hardness.Compared to the sole coagulation,PM/BS pre-oxidation combing with coagulation could neutralize the zeta potential of algal cells effectively,decrease the algal cell size,and lead to the formation of more compact flocs due to the in-situ generated Mn02.The effect of oxidant dosages on algal organic matter(AOM)was also studied and no obvious release of macromolecular substances was observed with the dosage of KMn04 increasing from 3.0 mg/L to 7.0 mg/L,suggesting the integrity of algal cells at a high KMn04 dosage.Moreover,PM/BS pre-oxidation could lead to the decrease of most analyzed disinfection by-products(DBPs)at a Al2(SO4)3 dosage of 40.0 mg/L.The algae removal efficiency was also significantly enhanced by PM/BS pre-oxidation in the test using real algae-laden water.This study indicated that PM/BS process might be a potential assistant technology for algae removal by subsequent coagulation.展开更多
The effectiveness of enhancing treatment of water with low turbidity through combined effects of permanganate oxidation, PAM aiding coagulation and sludge recycling was investigated through continuous bench scale stud...The effectiveness of enhancing treatment of water with low turbidity through combined effects of permanganate oxidation, PAM aiding coagulation and sludge recycling was investigated through continuous bench scale studies. In comparing with ferric chloride coagulation, only recycling sedimentation sludge was ineffective in enhancing treatment of water with low turbidity. PAM with recycled sludge showed positive effects, and the additional permanganate dosing exhibited the best potential of favoring coagulation, which leaded to much lower effluent turbidity and CODMa. Additionally, it was observed that the optimal permanganate dosage was 0. 4 mg/ L and the higher permanganate dosage exhibited inhibiting effects for pollutants removal. SEM analysis indicated that the floes were loosely formed and the particle diameter was critically low for ferric chloride coagulation process. Comparatively, the addition of PAM and permanganate with recycled sludge facilitated the aggregation of tinny particles onto compact PAM polymer chains, therefore contributing to the formation of compact floes with high particle diameter. The combined employment of recycled sludge, PAM and permanganate showed the best potential of favoring coagulation, mainly through synergistic effects between seeding, polymer bridging and increasing effective collision in mechanism. Additionally, the variation of Fe and Mn concentration after recycling and sedimentating units was studied for the processes, and the main species was also investigated for elements Fe and Mn. Sludge recycling and permanganate addition did not increase Fe and Mn concentration in the sedimented water.展开更多
Permanganate has attracted much attention in wide range of chemistry and particularly in degradation of environmental pollutants.However,few studies have discussed the feature of regioselective reactivity of permangan...Permanganate has attracted much attention in wide range of chemistry and particularly in degradation of environmental pollutants.However,few studies have discussed the feature of regioselective reactivity of permanganate with specific moiety of the target compound.Herein,we studied the reaction between permanganate and tetracycline that is an emerging micropollutant with different species containing several electron-rich groups.The second-order rate constants increased from 6.0 to 9.0 and could be quantitatively modeled by considering the speciation of both reactants,yielding kTC0=11.7(mol/L)^-1 sec^-1,kTC-=35.7(mol/L)^-1 sec^-1,kTC2-=43.1(mol/L)^-1 sec^-1 for individual reaction channels.Degradation products were then identified as the hydroxylated and demethylated compounds.The result suggested a rate-limiting step of simple hydroxylation at the phenolic and/or alkene moieties,while the demethylation should be caused by the unavoidably formed manganese oxide via single electron oxidation.This is supported by the DFT calculation,indicating the primary oxidation of phenolic group of TC0 with activation barrier of 44.5 kcal/mol and of alkene group of TC-and TC2-with activation barriers of 44.0 and 43.4 kcal/mol,respectively.This is in agreement with the experimental results,implying the alternation of regioselectivity associated with the deprotonation process.The result was further supported by performing the Fukui function and electrostatic potential analysis,reflecting the more probable site and better electron donating tendency beneficial to the permanganate oxidation.展开更多
A high sensitive flow-injection chemiluminescence （FI-CL） method for the determination of tryptophan has been developed. The method is based on the chemiluminescence reaction of galangin-potassium permanganate-trypt...A high sensitive flow-injection chemiluminescence （FI-CL） method for the determination of tryptophan has been developed. The method is based on the chemiluminescence reaction of galangin-potassium permanganate-tryptophan in polyphosphoric acid （PPA） media. Under the optimized conditions, tryptophan was determined in the range 0.05-10 μg/mL with the detection limit （3tr） of 5.0 × 10^-3 μg/mL. The relative standard deviation （RSD） was 1.0% for 11 replicate determinations of 1.0 μg/mL tryptophan. Three synthetic samples were determined selectively with recoveries in the range from 99.6% to 102.0% in the presence of other amino acids.展开更多
Excess amount of potassium permanganate has often been used in-situ for chemical oxidation of contaminated sites. The consequences are not limited to secondary contamination and cost but also inefficient remediation. ...Excess amount of potassium permanganate has often been used in-situ for chemical oxidation of contaminated sites. The consequences are not limited to secondary contamination and cost but also inefficient remediation. Encapsulation of permanganate using PMMA enables controlled dissolution of the oxidant and aids long-term processes. This paper focuses on the oxidant release efficiency from polymer matrix and analysis of data using existing models for glassy polymers. The efficiency profile obtained using mass ratios of 2:1, 4:1, and 8:1 of PMMA to KMnO4 showed a decrease in the extent of release with increasing mass ratio with 79%, 55.35% and 33.59% respectively. Patches were noticed on the surfaces of PMMA after the release of KMnO4, these were attributed to crevices created by the non-fickian diffusion of the oxidant.展开更多
The large consumption and discharge of diclofenac(DCF) lead to its frequent detection in surface water and groundwater, posing great threats to humans and ecosystems. This study explored the oxidation kinetics of DCF ...The large consumption and discharge of diclofenac(DCF) lead to its frequent detection in surface water and groundwater, posing great threats to humans and ecosystems. This study explored the oxidation kinetics of DCF by permanganate(Mn(Ⅶ)), and expounded the underlying reason for the unusual p Hdependency that was unclear in previous studies. The kinetics of DCF analogues(i.e., aromatic secondary amines) by Mn(Ⅶ) oxidation were comparatively investigated. Then, a tentative kinetic model involving the formation of an intermediate between Mn(Ⅶ) and DCF or its analogues was proposed to fit the p H-rate profile. Since DCF contained two chloro groups, and a carboxyl group which could be ionized by negative electrospray ionization, a precursor ionization scanning approach was used for the first time for detection of N-containing chlorinated oxidation products. New degradation pathways of DCF containing ring opening, carboxylation, carbonylation, electrophilic addition, hydroxylation and dehydrogenation were proposed based on the identified oxidation products. Moreover, it was demonstrated that the introduction of various reducing agents such as Mn(Ⅱ), Fe(Ⅱ) and bisulfite significantly improved the oxidation kinetics of DCF by Mn(Ⅶ). The positive effects of Mn(Ⅱ) and Fe(Ⅱ) were mainly attributed to the accelerated formation of MnO_(2)that acted as a catalyst or co-oxidizer contributing to DCF degradation. The presence of bisulfite caused two-stage kinetics, where a sharp drop of DCF concentration followed by a slowdown of DCF removal. In the first stage, potent reactive manganese species(e.g., Mn(Ⅲ), Mn(V), and Mn(VI)) and sulfate radical were generated during reaction of bisulfite with Mn(Ⅶ), whereas bisulfite was depleted fast due to excess Mn(Ⅶ) concentrations and the system became the Mn(Ⅶ)/MnO_(2)system in the second stage. These results provide new insight into reaction mechanism of DCF with Mn(Ⅶ)as well as propose a feasible strategy for enhancing the treatment of DCF contaminated water by Mn(Ⅶ).展开更多
Wet carbon-based solid acid and potassium permanganate were used as new reagents for oxidation of alcohols to their corresponding aldehydes and ketones in heterogeneous mixtures. The experiments were done moderately a...Wet carbon-based solid acid and potassium permanganate were used as new reagents for oxidation of alcohols to their corresponding aldehydes and ketones in heterogeneous mixtures. The experiments were done moderately at mild condition and high yields in suitable times were obtained.展开更多
The effects of potassium permanganate(KMnO_4)dosing position on the natural organic matter(NOM)removal as well as membrane fouling were investigated in the coagulation/ultrafiltration combined process.KMnO_4 oxidation...The effects of potassium permanganate(KMnO_4)dosing position on the natural organic matter(NOM)removal as well as membrane fouling were investigated in the coagulation/ultrafiltration combined process.KMnO_4 oxidation altered the NOM characteristics in terms of hydrophobicity and molecular weight,and destroyed humic substances originated from terraneous organisms in raw water.The optimal KMnO_4 dosage was 0.5 mg·L^(-1) in the peroxidation enhanced coagulation process with respect to the dissolved organic carbon(DOC)removal.When KMnO_4 was dosed into both upstream and downstream of coagulation,namely in the proposed twoposition dosing mode,coagulation and KMnO_4 oxidation worked individually on the apparent DOC removal.However,compared to the KMnO_4 addition prior to or after coagulation,the two-position dosing mode dramatically alleviated membrane fouling and reduced fouling irreversibility.This was attributed to the change of NOM characteristics as a result of KMnO_4 addition prior to coagulation and the presence of MnO_2 on membrane surface as a result of KMnO_4 addition prior to ultrafiltration.This work may provide useful information for the application of KMnO_4 oxidation in the coagulation/ultrafiltration combined system.展开更多
A submerged internal circulating membrane coagulation reactor （MCR） was used to treat surface water to produce drinking water. Polyaluminum chloride （PAC1） was used as coagulant, and a hydrophilic polyvinylidene f...A submerged internal circulating membrane coagulation reactor （MCR） was used to treat surface water to produce drinking water. Polyaluminum chloride （PAC1） was used as coagulant, and a hydrophilic polyvinylidene fluoride （PVDF） submerged hollow fiber microfiltration membrane was employed. The influences of trans-membrane pressure （TMP）, zeta potential （ZP） of the suspended particles in raw water, and KMnO4 dosing on water flux and the removal of turbidity and organic matter were systematically investigated. Continuous bench-scale experiments showed that the permeate quality of the MCR satisfied the requirement for a centralized water supply, according to the Standards for Drinking Water Quality of China （GB B749-2006）, as evaluated by turbidity （〈1 NTU） and total organic carbon （TOC） （〈5 mE/L） measurements. Besides water flux, the removal of turbidity, TOC and dissolved organic carbon （DOC） in the raw water also increased with increasing TMP in the range of 0.01-0.05 MPa. High ZP induced by PAC1, such as 5-9 mY, led to an increase in the number of fine and total particles in the MCR, and consequently caused serious membrane fouling and high permeate turbidity. However, the removal of TOC and DOC increased with increasing ZP. A slightly positive ZP, such as 1-2 mV, corresponding to charge neutralization coagulation, was favorable for membrane fouling control. Moreover, dosing with KMnO4 could further improve the removal of turbidity and DOC, thereby mitigating membrane fouling. The results are helpful for the application of the MCR in producing drinking water and also beneficial to the research and application of other coagulation and membrane separation hybrid processes.展开更多
Potassium permanganate (KMnO<sub>4</sub>) has been used widely as an oxidant for remediation of contaminated soil and water systems. The present study evaluates the release of this oxidant from Polycaprola...Potassium permanganate (KMnO<sub>4</sub>) has been used widely as an oxidant for remediation of contaminated soil and water systems. The present study evaluates the release of this oxidant from Polycaprolactone (PCL) polymer as part of a patented controlled release process (CRP) to be applied for targeted removal of contaminants from water. KMnO<sub>4</sub> was encapsulated into PCL at a 1:5 oxidant to polymer ratio and placed in batch reactor systems with reagent water to be evaluated over a 96 hour period. SEM images showed that over time, the number of cavities and their sizes increased on the waxy surface of the PCL polymer. The experimental data from the release of KMnO<sub>4</sub> from PCL was found to fit non-Fickian diffusion model after dissolution (R<sup>2</sup> = 0.93) similar to other systems that describe the dispersal of other oxidants from wax matrices. In addition, the model parameters for data of this present study were also found to be comparable to previous release studies with the same oxidant encapsulated in different wax matrices at similar ratios. Overall, the similarity of release data between the diversity of polymers shows that the controlled release biodegradable polymer utilizing PCL provides effective release of the KMnO<sub>4</sub> with the added benefit biodegradable nature of PCL.展开更多
Permanganate treatment is widely used for disinfection of bacteria in surface-contaminated water.In this paper,the fate of the dissolved permanganate in aqueous solution after contact with cells of Pseudomonas fluores...Permanganate treatment is widely used for disinfection of bacteria in surface-contaminated water.In this paper,the fate of the dissolved permanganate in aqueous solution after contact with cells of Pseudomonas fluorescens was studied.Concomitant accumulation of divalent cations of Mg2+,Zn2+,and Co2+during precipitation of Mn oxides was also studied.The time course of the Mn concentration in solution showed an abrupt decrease after contact of Mn(VII)with microbial cells,followed by an increase after^24 hr.XRD analysis of the precipitated Mn oxides,called biomass Mn oxides,showed the formation of low-crystalline birnessite.Visible spectroscopy and X-ray absorption near edge structure(XANES)analyses indicated that dissolved Mn(VII)was reduced to form biomass Mn oxides involving Mn(IV)and Mn(III),followed by reduction to soluble Mn(II).The numbers of electron transferred from microbial cells to permanganate and to biomass Mn oxides for 24 hr after the contact indicated that the numbers of electron transfer from microbial cell was approximately 50 times higher to dissolved permanganate than to the biomass Mn oxides in present experimental conditions.The 24 hr accumulation of divalent cations during formation of biomass Mn oxides was in the order of Co2+>Zn2+>Mg2+.XANES analysis of Co showed that oxidation of Co2+to Co3+resulted in higher accumulation of Co than Zn and Mg.Thus,treatment of surface water by KMnO4 solution is effective not only for disinfection of microorganisms,but also for the elimination of metal cations from surface water.展开更多
Permanganate/sulfite(Mn(VII)/S(IV))process is a promising pre-oxidation technology for sequestering the emerging organic contaminants in drinking water treatment plant.Iopamidol(IPM),a representative of iodinated X-ra...Permanganate/sulfite(Mn(VII)/S(IV))process is a promising pre-oxidation technology for sequestering the emerging organic contaminants in drinking water treatment plant.Iopamidol(IPM),a representative of iodinated X-ray contrast media,has been widely detected in water sources and has the risk of forming iodinated disinfection byproducts(I-DBPs)in water treatment system.In this study,we investigated the evolution of iodine species during the IPM degradation by the Mn(VII)/S(IV)process and its effect on the subsequent formation of I-DBPs during chlorination at pH 7.0 and 8.0.IPM could be effectively degraded in the Mn(VII)/S(IV)process at environmentally relevant pH(pH 7.0 and 8.0).The results of quenching and competitive oxidation kinetic experiments revealed that SO^(·-)_(4)was the major reactive oxidizing species contributing to the degradation of IPM whereas the contributions of HO·and reactive manganese species were negligible in the Mn(VII)/S(IV)process.I–and IO–3were generated while no HOI was detected during the degradation of IPM in the Mn(VII)/S(IV)process.The effects of IPM oxidation by Mn(VII)/S(IV)on the subsequent formation of chlorinated disinfection by-products(Cl-DBPs)during chlorination were related to the category of Cl-DBPs.The pre-oxidation of IPM by Mn(VII)/S(IV)resulted in the generation of I-DBPs during the disinfection process although no I-DBPs were detected if no pre-oxidation was applied.The finding of this study suggested that attention should be paid to the toxicity of DBPs when water containing iodinated organic contaminants is treated by Mn(VII)/S(IV)process or other pre-oxidation technologies.展开更多
A spectrophotometric investigation of oxidation of chondroitin-4-sulfate(CS)as a sustainable and biodegradable sulfated macromolecule by oxyanion permanganate ion as multi-equivalent oxidant in acid perchlorate soluti...A spectrophotometric investigation of oxidation of chondroitin-4-sulfate(CS)as a sustainable and biodegradable sulfated macromolecule by oxyanion permanganate ion as multi-equivalent oxidant in acid perchlorate solutions at a constant ionic strength of 2.0 mol dm^(-3)has been studied.The experimental results on the influence of the concentration of the reactants the reaction rates revealed first-order dependence in MnO^(-)_(4),fractional second-order in[CS]and fractional first-order with respect to the hydrogen ion concentration.The hydrogen acid concentration dependence of the rate constants indicated that the oxidation rates were increased with increasing the acid concentration which means that the oxidation reaction is of acid-catalyzed nature.The oxidation of all other polysaccharides by this oxidant in acidic solutions indicated that the oxidation processes were proceeding throughout two distinct stages.The first stage was relatively slow,followed by a more fast reaction in the second stage.The addition of Mn^(2+)and F^(-)ions to the reaction mixtures indicated that the Mn^(3+)and/or Mn^(4+)as the reduced forms of permanganate were the reactive species in the second fast stage.Here,neither formation of Mn^(3+)and/or Mn^(4+)transient species nor presence of two stages in the oxidation reaction were detected in the oxidation process,and this result was found to be on contrary to that observed for oxidation of all other polysaccharides by this oxidant.Formation of 1:2 coordination biopolymer intermediate complexes prior to the rate-determining step was revealed,kinetically.Identification of the oxidation product revealed the formation of keto-acid as derivative precursor of CS oxidation.This product was identified by formation of 2,4-dinitrophenyhydrazone and dioxime as wells as by the bands at frequencies 3430(OH of COOH group);1760-1730 cm^(-1)(broad)for C=O of diketone;1639 cm^(-1)ofν_(as),OCO;1418 cm^(-1)ofν_(s)OCO and 1338 cm^(-1)of C-O-C,respectively,in the FTIR spectra.Two-electron transfer process of inner-sphere nature in the slowest step has been suggested.A tentative reaction mechanism in terms of the kinetic parameters have been suggested and discussed.展开更多
基金support from the National Natural Science Foundation of China(Nos.52300102,523B2094)the Key Laboratory of Jiangxi Province for Persistent Pollutants Prevention Control and Resource Reuse(No.2023SSY02061)+1 种基金the Natural Science Foundation of Sichuan Province(No.2024NSFSC0130)Miaozi Project in Science and Technology Innovation Program of Sichuan Province(No.MZGC20230098)。
文摘Studies widely acknowledge the enhancement of permanganate(Mn(Ⅶ))oxidation of organic contaminants by coexisting matrices in water.This study investigated the positive influence of Mn(Ⅱ),a common soluble metal ion,on the removal of trace organic pollutants by Mn(Ⅶ).Results showed that introducing 20μmol/L Mn(Ⅱ)at pH 5.0 accelerated trace organic pollutant removal by promoting colloidal MnO_(2)formation.UV-vis spectrum,quenching,and probe experiments confirmed role of MnO_(2)in sulfamethoxazole(SMX)oxidation,with Mn(Ⅲ)playing a predominant role.Meanwhile,in situ-generated MnO_(2)facilitated Mn(Ⅶ)*formation,enhancing oxidation performance,as indicated by Raman spectroscopy and electrochemical analysis.Eleven transformation products(TPs)of SMX in the Mn(Ⅶ)/Mn(Ⅱ)process were detected by UPLC-QTOF-MS/MS.Subsequently,the reaction pathways of SMX were elucidated through Fukui index analysis and the identification of TPs.Additionally,toxicity simulations with Toxicity Estimation Software Tool(T.E.S.T.)software revealed significantly lower cytotoxicity of TPs of SMX compared to the parent compound.This study unveils an effective strategy to enhance Mn(Ⅶ)-mediated degradation of organic pollutants in water,elucidating Mn(Ⅱ)-induced Mn(Ⅶ)activation mechanisms.
文摘Using the glucose and L-glutamic-acid to prepare the standard substance according to the ratio of 1：1, and the artificial seawater and the standard substance to prepare a series of standard solutions, the distribution pattern of uncertainty in measurement of seawater COD is obtained based on the measured results of the series of standard solutions by the potassium iodide-alkaline potassium permanganate determination method. The distribution pattern is as follows： Uncertainty in measurement is big and not constant at the high end, but small and constant at the low end.
基金This work was supported by the National Natural Science Foundation of China （No. 20005005） the Chenguang Project of Wuhan City （No. 20005004026）.
文摘A novel chemiluminescence （CL） system for determination of permanganate index （CODMn） combined with flow injection analysis has been proposed in this study. On the basis of the chemiluminescent reaction of luminol-KMnO4 system, light emission caused by luminol-KMnO4 system was detected by the photomultiplier tube, and its intensity caused by the appearance of KMnO4 after sample digestion was inversely proportional to CODMn. Effects for CODMn determining such as pH, concentrations and interference were investigated in detail. A detection limit of 0.3 mg/L CODMn with a linear range of 0.3-200 mg/L for its theoretical CODMn was obtained under the optimized experimental conditions. The relative standard deviation was 4.3% for 5.0 mg/L CODMn （n = 11）. This CL flow system for determining CODMn was simple, rapid, and suitable for automatic analysis. The data obtained by the present method were fairly in good agreement with those obtained by the standard titrimetric method. It has been applied to determine real samples with satisfactory results.
文摘The oxidation of As（Ⅲ） with potassium permanganate was studied under conditions including pH, initial As（Ⅲ） concentration and dosage of Mn（Ⅶ）. The results have shown that potassium permanganate was an effective agent for oxidation of As（Ⅲ） in a wide pH range. The pH value of tested water was not a significant factor affecting the oxidation of As（Ⅲ） by Mn（Ⅲ）. Although theoretical redox analyses suggest that Mn（Ⅶ） should have better performance in oxidization of As（Ⅲ） within lower pH ranges, the experimental results show that the oxidation efficiencies of As（Ⅲ） under basic and acidic conditions were similar, which may be due to the adsorption of As（Ⅲ） on the Mn（OH）2 and MnO2 resulting from the oxidation of As（Ⅲ）.
基金supported by a grant from the National Natural Science Foundation of China(No.81201393)
文摘Summary： Traumatic gas gangrene is a fatal infection mainly caused by Clostridium perfringens. It is a challenge to manage gas gangrene in open wounds and control infection after debridement or amputa- tion. The aim of the present study was to use vacuum sealing drainage （VSD） with continuous irrigation of potassium permanganate to manage infective wounds of gas gangrene and observe its clinical effi- cacy. A total of 48 patients with open traumatic gas gangrene infection were included in this study. Am- putations were done for 27 patients, and limb salvage procedures were performed for the others. After amputation or aggressive debridement, the VSD system, including polyvinyl alcohol （PVA） foam dress- ing and polyurethane （PU） film, with continuous irrigation of 1：5000 potassium permanganate solutions, was applied to the wounds. During the follow-up, all the patients healed without recurrence within 8-18 months. There were four complications. Cardiac arrest during amputation surgery occurred in one pa- tient who suffered from severe septic shock. Emergent resuscitation was performed and the patient re- turned to stable condition. One patient suffered from mixed infection of Staphylococcal aureus, and a second-stage debridement was performed. One patient suffered from severe pain of the limb after the debridement. Exploratory operation was done and the possible reason was trauma of a local peripheral nerve. Three cases of crush syndrome had dialysis treatment for concomitant renal failure. In conclusion, VSD can convert open wound to closed wound, and evacuate necrotic tissues. Furthermore, potassium permanganate solutions help eliminate anaerobic microenviroument and achieve good therapeutic effect on gas gangrene and mixed infection. VSD with continuous irrigation of potassium permanganate is a novel, simple and feasible alternative for severe traumatic open wounds with gas gangrene infection.
基金supported by the National Natural Science Foundation of China (No. 21006059)the Project of Shandong Province Higher Educational Science and Technology Program (No. J11LB61)
文摘The adsorption characteristics of virgin and potassium permanganate modified lignite semi-coke （SC） for gaseous Hg were investigated in an attempt to produce more effective and lower price adsorbents for the control of elemental mercury emission. Brunauer-Emmett- Teller （BET） measurements, X-ray powder diffraction （XRD） and X-ray photoelectron spectroscopy （XPS） were used to analyze the surface physical and chemical properties of SC, Mn-SC and Mn-H-SC before and after mercury adsorption. The results indicated that potassium permanganate modification had significant influence on the properties of semi-coke, such as the specific surface area, pore structure and surface chemical functional groups. The mercury adsorption efficiency of modified semi-coke was lower than that of SC at low temperature, but much higher at high temperature. Amorphous Mn7＋, Mn6＋ and Mn4＋ on the surface of Mn-SC and Mn-H-SC were the active sites for oxidation and adsorption of gaseous Hg~, which oxidized the elemental mercury into Hg2＋ and captured it. Thermal treatment reduced the average oxidation degree of Mn2＋ on the surface of Mn-SC from 3.80 to 3.46. However, due to the formation of amorphous MnOx, the surface oxidation active sites for gaseous Hg0 increased, which gave Mn-H-SC higher mercury adsorption efficiency than that of Mn-SC at high temperature.
文摘Chlorine content and position of chlorinated phenols have many significant effects on the reactivity of oxido-reduction. The effects of chlorine content and position of chlorinated phenols on their oxidation kinetics by potassium permanganate were evaluated through different kinetics studies. Since chlorine was an electron withdrawing atom, the substitution of chlorine on the aromatic ring decreased the oxidation rate constant by σ-electron withdrawing conductive effect. The substitution of chlorine at ortho or para position on the aromatic ring increased the oxidation rate constant by π-electron donating conjugative effect, and the conjugative effect could counteract the negative impact of the conductive effect to some extent. On the other hand, the substitution of chlorine at ortho position on the aromatic ring decreased the oxidation rate constant by steric hindrance effect. The oxidation rate constants of phenol and chlorinated phenols studied decreased as follow order: 4-chlorophenol>2,4-dichlorophenol>phenol>2,6-dichlorophenol.
基金supported by the National Natural Science Foundation of China(No.21976133)。
文摘The effects of bisulfite-activated permanganate technology(PM/BS)as a pre-oxidation process on enhancing Microcystis aeruginosa(M.aeruginosa)removal by post coagulation were investigated.The results demonstrated that pretreatment with PM/BS process effectively promoted the algae removal by coagulation with Al2(SO4)3 as the coagulant and this phenomenon was more obvious with the increase of water hardness.Compared to the sole coagulation,PM/BS pre-oxidation combing with coagulation could neutralize the zeta potential of algal cells effectively,decrease the algal cell size,and lead to the formation of more compact flocs due to the in-situ generated Mn02.The effect of oxidant dosages on algal organic matter(AOM)was also studied and no obvious release of macromolecular substances was observed with the dosage of KMn04 increasing from 3.0 mg/L to 7.0 mg/L,suggesting the integrity of algal cells at a high KMn04 dosage.Moreover,PM/BS pre-oxidation could lead to the decrease of most analyzed disinfection by-products(DBPs)at a Al2(SO4)3 dosage of 40.0 mg/L.The algae removal efficiency was also significantly enhanced by PM/BS pre-oxidation in the test using real algae-laden water.This study indicated that PM/BS process might be a potential assistant technology for algae removal by subsequent coagulation.
基金Sponsored by the National High Technology Research and Development Program of China(Grant No.2004AA601020)
文摘The effectiveness of enhancing treatment of water with low turbidity through combined effects of permanganate oxidation, PAM aiding coagulation and sludge recycling was investigated through continuous bench scale studies. In comparing with ferric chloride coagulation, only recycling sedimentation sludge was ineffective in enhancing treatment of water with low turbidity. PAM with recycled sludge showed positive effects, and the additional permanganate dosing exhibited the best potential of favoring coagulation, which leaded to much lower effluent turbidity and CODMa. Additionally, it was observed that the optimal permanganate dosage was 0. 4 mg/ L and the higher permanganate dosage exhibited inhibiting effects for pollutants removal. SEM analysis indicated that the floes were loosely formed and the particle diameter was critically low for ferric chloride coagulation process. Comparatively, the addition of PAM and permanganate with recycled sludge facilitated the aggregation of tinny particles onto compact PAM polymer chains, therefore contributing to the formation of compact floes with high particle diameter. The combined employment of recycled sludge, PAM and permanganate showed the best potential of favoring coagulation, mainly through synergistic effects between seeding, polymer bridging and increasing effective collision in mechanism. Additionally, the variation of Fe and Mn concentration after recycling and sedimentating units was studied for the processes, and the main species was also investigated for elements Fe and Mn. Sludge recycling and permanganate addition did not increase Fe and Mn concentration in the sedimented water.
基金supported by the National Key R&D Program of China(No.2018YFC0406304)the Central Public-Interest Scientific Institution Basal Research Fund(No.1610232019005)the Agricultural Science and Technology Innovation Program(No.ASTIPTRIC06)
文摘Permanganate has attracted much attention in wide range of chemistry and particularly in degradation of environmental pollutants.However,few studies have discussed the feature of regioselective reactivity of permanganate with specific moiety of the target compound.Herein,we studied the reaction between permanganate and tetracycline that is an emerging micropollutant with different species containing several electron-rich groups.The second-order rate constants increased from 6.0 to 9.0 and could be quantitatively modeled by considering the speciation of both reactants,yielding kTC0=11.7(mol/L)^-1 sec^-1,kTC-=35.7(mol/L)^-1 sec^-1,kTC2-=43.1(mol/L)^-1 sec^-1 for individual reaction channels.Degradation products were then identified as the hydroxylated and demethylated compounds.The result suggested a rate-limiting step of simple hydroxylation at the phenolic and/or alkene moieties,while the demethylation should be caused by the unavoidably formed manganese oxide via single electron oxidation.This is supported by the DFT calculation,indicating the primary oxidation of phenolic group of TC0 with activation barrier of 44.5 kcal/mol and of alkene group of TC-and TC2-with activation barriers of 44.0 and 43.4 kcal/mol,respectively.This is in agreement with the experimental results,implying the alternation of regioselectivity associated with the deprotonation process.The result was further supported by performing the Fukui function and electrostatic potential analysis,reflecting the more probable site and better electron donating tendency beneficial to the permanganate oxidation.
文摘A high sensitive flow-injection chemiluminescence （FI-CL） method for the determination of tryptophan has been developed. The method is based on the chemiluminescence reaction of galangin-potassium permanganate-tryptophan in polyphosphoric acid （PPA） media. Under the optimized conditions, tryptophan was determined in the range 0.05-10 μg/mL with the detection limit （3tr） of 5.0 × 10^-3 μg/mL. The relative standard deviation （RSD） was 1.0% for 11 replicate determinations of 1.0 μg/mL tryptophan. Three synthetic samples were determined selectively with recoveries in the range from 99.6% to 102.0% in the presence of other amino acids.
文摘Excess amount of potassium permanganate has often been used in-situ for chemical oxidation of contaminated sites. The consequences are not limited to secondary contamination and cost but also inefficient remediation. Encapsulation of permanganate using PMMA enables controlled dissolution of the oxidant and aids long-term processes. This paper focuses on the oxidant release efficiency from polymer matrix and analysis of data using existing models for glassy polymers. The efficiency profile obtained using mass ratios of 2:1, 4:1, and 8:1 of PMMA to KMnO4 showed a decrease in the extent of release with increasing mass ratio with 79%, 55.35% and 33.59% respectively. Patches were noticed on the surfaces of PMMA after the release of KMnO4, these were attributed to crevices created by the non-fickian diffusion of the oxidant.
基金financially supported by the program for the National Natural Science Foundation of China (Nos. 51979044,42177045 and 42107053)the Guangdong Natural Science Funds for Distinguished Young Scholar (No. 2019B151502023)+2 种基金Guangdong International Training Program for Outstanding Young Talentsthe China Postdoctoral Science Foundation (No. 2021M700878)Guangdong-Hong Kong-Macao Joint Laboratory for Contaminants Exposure and Health (No. 2020B1212030008)。
文摘The large consumption and discharge of diclofenac(DCF) lead to its frequent detection in surface water and groundwater, posing great threats to humans and ecosystems. This study explored the oxidation kinetics of DCF by permanganate(Mn(Ⅶ)), and expounded the underlying reason for the unusual p Hdependency that was unclear in previous studies. The kinetics of DCF analogues(i.e., aromatic secondary amines) by Mn(Ⅶ) oxidation were comparatively investigated. Then, a tentative kinetic model involving the formation of an intermediate between Mn(Ⅶ) and DCF or its analogues was proposed to fit the p H-rate profile. Since DCF contained two chloro groups, and a carboxyl group which could be ionized by negative electrospray ionization, a precursor ionization scanning approach was used for the first time for detection of N-containing chlorinated oxidation products. New degradation pathways of DCF containing ring opening, carboxylation, carbonylation, electrophilic addition, hydroxylation and dehydrogenation were proposed based on the identified oxidation products. Moreover, it was demonstrated that the introduction of various reducing agents such as Mn(Ⅱ), Fe(Ⅱ) and bisulfite significantly improved the oxidation kinetics of DCF by Mn(Ⅶ). The positive effects of Mn(Ⅱ) and Fe(Ⅱ) were mainly attributed to the accelerated formation of MnO_(2)that acted as a catalyst or co-oxidizer contributing to DCF degradation. The presence of bisulfite caused two-stage kinetics, where a sharp drop of DCF concentration followed by a slowdown of DCF removal. In the first stage, potent reactive manganese species(e.g., Mn(Ⅲ), Mn(V), and Mn(VI)) and sulfate radical were generated during reaction of bisulfite with Mn(Ⅶ), whereas bisulfite was depleted fast due to excess Mn(Ⅶ) concentrations and the system became the Mn(Ⅶ)/MnO_(2)system in the second stage. These results provide new insight into reaction mechanism of DCF with Mn(Ⅶ)as well as propose a feasible strategy for enhancing the treatment of DCF contaminated water by Mn(Ⅶ).
文摘Wet carbon-based solid acid and potassium permanganate were used as new reagents for oxidation of alcohols to their corresponding aldehydes and ketones in heterogeneous mixtures. The experiments were done moderately at mild condition and high yields in suitable times were obtained.
基金Supported by the National Natural Science Foundation of China(51478314,51638011)the National Key Project for Research and Development Program of China(2016YFC0400503)+1 种基金the Natural Science Foundation of Tianjin(14JCQNJC09000)Science and Technology Research Projects of Colleges and Universities of Hebei Province(QN2015122)
文摘The effects of potassium permanganate(KMnO_4)dosing position on the natural organic matter(NOM)removal as well as membrane fouling were investigated in the coagulation/ultrafiltration combined process.KMnO_4 oxidation altered the NOM characteristics in terms of hydrophobicity and molecular weight,and destroyed humic substances originated from terraneous organisms in raw water.The optimal KMnO_4 dosage was 0.5 mg·L^(-1) in the peroxidation enhanced coagulation process with respect to the dissolved organic carbon(DOC)removal.When KMnO_4 was dosed into both upstream and downstream of coagulation,namely in the proposed twoposition dosing mode,coagulation and KMnO_4 oxidation worked individually on the apparent DOC removal.However,compared to the KMnO_4 addition prior to or after coagulation,the two-position dosing mode dramatically alleviated membrane fouling and reduced fouling irreversibility.This was attributed to the change of NOM characteristics as a result of KMnO_4 addition prior to coagulation and the presence of MnO_2 on membrane surface as a result of KMnO_4 addition prior to ultrafiltration.This work may provide useful information for the application of KMnO_4 oxidation in the coagulation/ultrafiltration combined system.
基金supported by the Special Funds for Technological Development of Research Institutes from the Ministry of Science and Technology of China(Nos.2012EG111122,2013EG111129,2014EG111126)the Program for Overseas Talents from Beijing Academy of Science and Technology(No.OTP-2013-015)the Six Talent Peaks Program from Jiangsu Province(No.JNHB-012)
文摘A submerged internal circulating membrane coagulation reactor （MCR） was used to treat surface water to produce drinking water. Polyaluminum chloride （PAC1） was used as coagulant, and a hydrophilic polyvinylidene fluoride （PVDF） submerged hollow fiber microfiltration membrane was employed. The influences of trans-membrane pressure （TMP）, zeta potential （ZP） of the suspended particles in raw water, and KMnO4 dosing on water flux and the removal of turbidity and organic matter were systematically investigated. Continuous bench-scale experiments showed that the permeate quality of the MCR satisfied the requirement for a centralized water supply, according to the Standards for Drinking Water Quality of China （GB B749-2006）, as evaluated by turbidity （〈1 NTU） and total organic carbon （TOC） （〈5 mE/L） measurements. Besides water flux, the removal of turbidity, TOC and dissolved organic carbon （DOC） in the raw water also increased with increasing TMP in the range of 0.01-0.05 MPa. High ZP induced by PAC1, such as 5-9 mY, led to an increase in the number of fine and total particles in the MCR, and consequently caused serious membrane fouling and high permeate turbidity. However, the removal of TOC and DOC increased with increasing ZP. A slightly positive ZP, such as 1-2 mV, corresponding to charge neutralization coagulation, was favorable for membrane fouling control. Moreover, dosing with KMnO4 could further improve the removal of turbidity and DOC, thereby mitigating membrane fouling. The results are helpful for the application of the MCR in producing drinking water and also beneficial to the research and application of other coagulation and membrane separation hybrid processes.
文摘Potassium permanganate (KMnO<sub>4</sub>) has been used widely as an oxidant for remediation of contaminated soil and water systems. The present study evaluates the release of this oxidant from Polycaprolactone (PCL) polymer as part of a patented controlled release process (CRP) to be applied for targeted removal of contaminants from water. KMnO<sub>4</sub> was encapsulated into PCL at a 1:5 oxidant to polymer ratio and placed in batch reactor systems with reagent water to be evaluated over a 96 hour period. SEM images showed that over time, the number of cavities and their sizes increased on the waxy surface of the PCL polymer. The experimental data from the release of KMnO<sub>4</sub> from PCL was found to fit non-Fickian diffusion model after dissolution (R<sup>2</sup> = 0.93) similar to other systems that describe the dispersal of other oxidants from wax matrices. In addition, the model parameters for data of this present study were also found to be comparable to previous release studies with the same oxidant encapsulated in different wax matrices at similar ratios. Overall, the similarity of release data between the diversity of polymers shows that the controlled release biodegradable polymer utilizing PCL provides effective release of the KMnO<sub>4</sub> with the added benefit biodegradable nature of PCL.
基金Financial support was provided to TO by the Japan Society for the Promotion of Science (JSPS Grant-in-Aid for Scientific Research No. 17K19086)performed with the approval of the Photon Factory, KEK (Proposal NO. 2012G179)
文摘Permanganate treatment is widely used for disinfection of bacteria in surface-contaminated water.In this paper,the fate of the dissolved permanganate in aqueous solution after contact with cells of Pseudomonas fluorescens was studied.Concomitant accumulation of divalent cations of Mg2+,Zn2+,and Co2+during precipitation of Mn oxides was also studied.The time course of the Mn concentration in solution showed an abrupt decrease after contact of Mn(VII)with microbial cells,followed by an increase after^24 hr.XRD analysis of the precipitated Mn oxides,called biomass Mn oxides,showed the formation of low-crystalline birnessite.Visible spectroscopy and X-ray absorption near edge structure(XANES)analyses indicated that dissolved Mn(VII)was reduced to form biomass Mn oxides involving Mn(IV)and Mn(III),followed by reduction to soluble Mn(II).The numbers of electron transferred from microbial cells to permanganate and to biomass Mn oxides for 24 hr after the contact indicated that the numbers of electron transfer from microbial cell was approximately 50 times higher to dissolved permanganate than to the biomass Mn oxides in present experimental conditions.The 24 hr accumulation of divalent cations during formation of biomass Mn oxides was in the order of Co2+>Zn2+>Mg2+.XANES analysis of Co showed that oxidation of Co2+to Co3+resulted in higher accumulation of Co than Zn and Mg.Thus,treatment of surface water by KMnO4 solution is effective not only for disinfection of microorganisms,but also for the elimination of metal cations from surface water.
基金supported by the National Natural Science Foundation of China (Nos.22206050,22025601,21976133 and 52270047)the National Key Research and Development Program of China (No.2019YFC1805202)the State Key Laboratory of Pollution Control and Resource Reuse Foundation (No.PCRRK20014)。
文摘Permanganate/sulfite(Mn(VII)/S(IV))process is a promising pre-oxidation technology for sequestering the emerging organic contaminants in drinking water treatment plant.Iopamidol(IPM),a representative of iodinated X-ray contrast media,has been widely detected in water sources and has the risk of forming iodinated disinfection byproducts(I-DBPs)in water treatment system.In this study,we investigated the evolution of iodine species during the IPM degradation by the Mn(VII)/S(IV)process and its effect on the subsequent formation of I-DBPs during chlorination at pH 7.0 and 8.0.IPM could be effectively degraded in the Mn(VII)/S(IV)process at environmentally relevant pH(pH 7.0 and 8.0).The results of quenching and competitive oxidation kinetic experiments revealed that SO^(·-)_(4)was the major reactive oxidizing species contributing to the degradation of IPM whereas the contributions of HO·and reactive manganese species were negligible in the Mn(VII)/S(IV)process.I–and IO–3were generated while no HOI was detected during the degradation of IPM in the Mn(VII)/S(IV)process.The effects of IPM oxidation by Mn(VII)/S(IV)on the subsequent formation of chlorinated disinfection by-products(Cl-DBPs)during chlorination were related to the category of Cl-DBPs.The pre-oxidation of IPM by Mn(VII)/S(IV)resulted in the generation of I-DBPs during the disinfection process although no I-DBPs were detected if no pre-oxidation was applied.The finding of this study suggested that attention should be paid to the toxicity of DBPs when water containing iodinated organic contaminants is treated by Mn(VII)/S(IV)process or other pre-oxidation technologies.
基金supported by the Department of Chemistry,Faculty of Science,Assiut University,Assiut,71516,Assiut,Egypt.
文摘A spectrophotometric investigation of oxidation of chondroitin-4-sulfate(CS)as a sustainable and biodegradable sulfated macromolecule by oxyanion permanganate ion as multi-equivalent oxidant in acid perchlorate solutions at a constant ionic strength of 2.0 mol dm^(-3)has been studied.The experimental results on the influence of the concentration of the reactants the reaction rates revealed first-order dependence in MnO^(-)_(4),fractional second-order in[CS]and fractional first-order with respect to the hydrogen ion concentration.The hydrogen acid concentration dependence of the rate constants indicated that the oxidation rates were increased with increasing the acid concentration which means that the oxidation reaction is of acid-catalyzed nature.The oxidation of all other polysaccharides by this oxidant in acidic solutions indicated that the oxidation processes were proceeding throughout two distinct stages.The first stage was relatively slow,followed by a more fast reaction in the second stage.The addition of Mn^(2+)and F^(-)ions to the reaction mixtures indicated that the Mn^(3+)and/or Mn^(4+)as the reduced forms of permanganate were the reactive species in the second fast stage.Here,neither formation of Mn^(3+)and/or Mn^(4+)transient species nor presence of two stages in the oxidation reaction were detected in the oxidation process,and this result was found to be on contrary to that observed for oxidation of all other polysaccharides by this oxidant.Formation of 1:2 coordination biopolymer intermediate complexes prior to the rate-determining step was revealed,kinetically.Identification of the oxidation product revealed the formation of keto-acid as derivative precursor of CS oxidation.This product was identified by formation of 2,4-dinitrophenyhydrazone and dioxime as wells as by the bands at frequencies 3430(OH of COOH group);1760-1730 cm^(-1)(broad)for C=O of diketone;1639 cm^(-1)ofν_(as),OCO;1418 cm^(-1)ofν_(s)OCO and 1338 cm^(-1)of C-O-C,respectively,in the FTIR spectra.Two-electron transfer process of inner-sphere nature in the slowest step has been suggested.A tentative reaction mechanism in terms of the kinetic parameters have been suggested and discussed.
