Iron-glutamate-silicotungstate ternary complex as highly active heterogeneous Fenton-like catalyst for 4-chlorophenol degradation

A novel iron-glutamate-silicotungstate ternary complex（FeШGluS iW） was synthesized from ferric chloride（FeI II）,glutamic acid（Glu）,and silicotungstic acid（SiW）,and used as a heterogeneous Fenton-like catalyst for 4-chlorophenol（4-CP） degradation at neutral pH value. The prepared FeШGluS iW was characterized using inductively coupled plasma atomic emission spectroscopy,thermogravimetry,Fourier-transform infrared spectroscopy,ultraviolet-visible diffuse reflectance spectroscopy,X-ray diffraction,and field-emission scanning electron microscopy. The results showed that FeШGluS iW has the formula [Fe（C5H8NO4）（H2O）]2SiW 12O40？13H2O,with glutamate moiety and Keggin-structured SiW 12O404- heteropolyanion. The catalyst showed high catalytic activity in 4-CP degradation in the dark and under irradiation. Under the conditions of 4-CP 100 mg/L,FeШGluS iW 1.0 g/L,H2O2 20 mmol/L,and pH = 6.5,4-CP was completely decomposed in 40 min in the dark and in 15 min under irradiation. When the reaction time was prolonged to 2 h,the corresponding total organic carbon removals under dark and irradiated conditions were ca. 27% and 72%,respectively. The high catalytic activity of FeI IIGluS iW is resulted from hydrogen bonding of H2O2 on the FeI IIGluS iW surface. The enhanced degradation of 4-CP under irradiation arises from simultaneous oxidation of 4-CP through Fenton-like and photocatalytic processes respectively catalyzed by ferric iron and the SiW 12O404- hetropolyanion in FeШGluS iW.

Treatment of 2-phenylamino-3-methyl-6-di-n-butylaminofluoran production effluent by combination of biological treatments and Fenton's oxidation

High strength refractory organic stream is produced during the production of 2-phenylamino-3-methyl-6-di-n-butylaminofluoran （One Dye Black 2, abbr. ODB 2）, a novel heat-sensitive material with a promising market. In this study, a combination of acidificationprecipitation, primary biological treatment, Fenton＇s oxidation and another biological treatment was successfully used for the removal of COD from 18000-25000 mg/L to below 200 mg/L from the ODB 2 production wastewater in a pilot experiment. A COD removal of 70%-80% was achieved by acidification-precipitation under a pH of 2.5-3.0. The first step biodegradafion permitted an average COD removal of 70% under an hydraulic residence time （HRT） of 30 h. By batch tests, the optimum conditions of Fenton＇s oxidation were acquired as： Fe^2＋ dose 6.0 mmol/L; H2O2 dose 3000 mg/L; and reaction time 6 h. The second step biological treatment could ensure an effluent COD below 200 mg/L under an HRT of 10 h following the Fenton＇s treatment.

A Molecular Mechanism of Fenton Oxidation Degradation of m-Xylene

Density functional theory（DFT） quantum chemical method was used to study the process of meta-xylene Fenton oxidation. The EHOMO energies of meta-xylene molecules are higher, so they have better ability to provide electron and prone to the nucleophilic reaction. M-xylene mainly reacts with OH free radical in addition reactions. And the position of C（6） is most likely to react with the OH free radical, rather than the C（3）, which is the most difficult to occur. According to all the above results, the most likely reaction mechanism of advanced oxidation degradation of meta-xylene is determined.

Treatment of Oil Field Wastewater after Chemical Flooding by Fenton Oxidation Combined with Biodegradation

Wastewater after chemical flooding is difficult to be treated by biological methods due to the residual chemicals in the wastewater. Fenton oxidation, which has been widely applied to detoxifying hazardous organic compounds and improving the biodegradability of these compounds, can solve this problem. So, in this paper, Fenton oxidation was used to enhance the biodegradability of the wastewater after chemical flooding. The op- timum operating conditions for the Fenton oxidation process were 2.5 g/L Fe2 ＋ , 600 mg/L H202 and 30 rain of treatment time. The wastewater pre- treated by Fenton oxidation was treated by aerobic activated sludge. It was found that a small amount of H202 can significantly increase both the biodegradation rate and extent of the wastewater. The effluent CODc, and HPAM contents were 260 and 94 mg/L respectively after the aerobic bio- logical process with the biodegradation time of 24 h. After Fenton oxidation combining with biodegradation, the total CODc, removal efficiency was up to 90%, and polymer and oil degrading efficiencies were 95% and 92% respectively.

Effect of different surfactants on removal efficiency of heavy metals in sewage sludge treated by a novel method combining bio-acidification with Fenton oxidation

The aim of this work was to investigate the effect of different surfactants on the removal efficiency of heavy metals in sewage sludge treated by a method combining bio-acidification with Fenton oxidation. Four surfactants were adopted such as anionic surfactant(sodium dodecyl benzene sulfonate, SDBS), nonionic surfactants(tween-20 and tween-60) and cationic surfactant(hexadecyl trimethyl ammonium chloride, HTAC), respectively. The indigenous sulfur-oxidizing bacteria in bio-acidification phase were enriched and cultured from fresh activated sludge obtained from a wastewater treatment plant. It is shown that different surfactants exhibited distinct effect on the removal efficiency of heavy metals from sewage sludge. The nonionic surfactants,especially tween-60, promotes the solubilization of heavy metals, while the anionic and cationic surfactants hinder the removal of heavy metals. Copper is efficiently leached. The removal efficiency of cadium is relatively lower than that of Cu due to the demand for rigorous p H value. Lead is leached with a low efficiency as the formation of low soluble Pb SO4 precipitates.

Effects of Influencing Factors on Fenton Oxidation of Antibiotic Pharmaceutical Wastewater by a Statistical Design Approach

A series of batch-scale experiments were completed to investigate the effects of operational parameters on chemical oxygen demand (COD) removal by Fenton reagent for antibiotic pharmaceutical wastewater (APW). The significance of five operational factors including the mass ratio of H2O2/COD (g/g), the mole ratio of H2O2/Fe2+ (mol/mol), initial pH, oxidation temperature T, and reaction time t were evaluated statistically by Box-Behnken design (BBD). It was found that the five parameters were all significant to the COD removal efficiency by t-test, as well as the interactions between mass ratio/reaction time and oxidation temperature/reaction. The optimal COD removal efficiency (89.50%) was achieved when the mass ratio of H2O2/COD and the mole ratio of H2O2/Fe2+ were 3.00 and 5.00 respectively, with pH value of 3.68 at 298K for 72min reaction. A quadratic regression model with 0.9907 regression coefficient (R2) was developed which had good agreement to the experimental data.

Operating Conditions Optimization on Indonesian ＂Batik＂ Dyes Wastewater Treatment by Fenton Oxidation and Separation Using Ultrafiltration Membrane

Broadly speaking, this study aims to develop ＂batik＂ dyes wastewater treatment technologies by hybrid process that combines Fenton oxidation and separation using ultrafiltration membranes. Specifically, the purpose of this study was to determine the effect of membrane characteristics, feed solution pH, operating pressure of ＂Dead-end＂ membrane reactor, and the frequency of membranes which uses on the percentage of COD reduction in ＂batik＂ wastewater. In this study, the filtrate from wastewater pre-treatment with Fenton oxidation, both without and with addition of activated carbon, is passed to the ultrafiltration （UF） separation system. Fenton oxidation process was carried out at optimum conditions, i.e. at pH 3, temperature 50 ℃, and the addition FeSO4·7H2O and H2O2 at 747-830 mg/L and 1,168-1,460 mg/L, respectively. The optimum reduction percentage of COD can be achieved when the membranes used for separation has a pore size of 0.01 to 0.015 lam, feed solution pH 2, operating pressure 1 atm and frequency of membranes uses I x. To determine the fouling potential on ultrafiltration membranes that are used, flux measurements were performed 3 times for each membrane. These stages can see that the flux decline reached 22.5% when the effluent filtered directly to the membrane; 17.3% when performed pre-treatment prior to separation processes using membranes and 10% when combined pre-treatment process, use of activated carbon and the separation using ultrafiltration membranes.

Treatment Processes of Leachate from a Landfill by Advanced Oxidation Fenton and Ozone-UV

In this paper it is presented the results of advanced oxidation of leachates from a technified sanitary landfill located in the State of Querétaro, Mexico. One characteristic of already stabilized leachates from sanitary landfills like this case, is their difficult degradation, mainly because the organic matter contained is recalcitrant. For the samples collect, four sites were selected, where three points per site were sampled, measuring at each site the parameters: temperature, pH, conductivity, redox potential (ORP) and dissolved oxygen (DO) and leachate samples were collected. On the other hand, the Chemical Oxygen Demand (COD) of crude leachates, leachates acidified and leachates oxidized by Fenton reagent and Ozone-UV combined were analyzed. COD was used to monitor the degradation kinetics. With the results, the ArcGIS software was applied to study the distribution of temperature, dissolved oxygen and COD mainly in the leachate lagoon. For the application of Fenton reagent in the crude leachate oxidation, the pH was first adjusted and Fe2+/H2O2 ratio was optimized. The efficiency of Ozone-UV treatments was studied through COD degradation kinetics. The graphs of in (Ci/Co) vs time, showed that the kinetic processes are of order one, with very acceptable regression coefficients (R2) and extraordinarily similar speed constants (K). With Fenton oxidation, the highest percentage of COD degradation was achieved and with Ozone-UV oxidation, it was possible to practically degrade all the COD.

Mediated electron transfer process in α-MnO_(2)catalyzed Fenton-like reaction for oxytetracycline degradation

In Fenton-like oxidation,the catalyst directly influences the reaction mechanism for the degradation of pollutants from water.Here,a α-MnO_(2)catalyst(OAm-1)was synthesized via a self-assembly method with the assistance of a surfactant.OAm-1 possessed a large specific surface area of_(2)21 m2/g,abundant mesoporous structures and a large proportion of Mn(III).Further characterization exhibited that OAm-1 had abundant oxygen vacancies and excellent reducibility and conductivity.The adsorption and catalytic ability of OAm-1 were studied in the degradation of oxytetracycline(OTC)via the activation of hydrogen peroxide(H_(2)O_(2)).Through the radical quenching experiments,electron resonance spectroscopy(EPR),X-ray photoelectron spectroscopy(XPS)and Fourier-transform infrared spectroscopy(FT-IR)analysis,Mn(III)of OAm-1 was proved to be the active sites for the chemisorption of OTC.Systematic electrochemical ex-periments and analysis have shown that a process of electron transfer mediated by OAm-1 occurred be-tween the pollutant and H_(2)O_(2)during a Fenton-like reaction.This work experimentally verifies the elec-tron transfer process dominated nonradical mechanism overα-MnO_(2),which is helpful for understanding the catalytic mechanism of the Fenton-like oxidation.

Advanced treatment of dyeing wastewater towards reuse by the combined Fenton oxidation and membrane bioreactor process

The performance of combined Fenton oxidation and membrane bioreactor （MBR） process for the advanced treatment of an effluent from an integrated dyeing wastewater treatment plant was evaluated. The experimental results revealed that under the optimum Fenton oxidation conditions （initial pH 5, H 2 O 2 dosage 17 mmol/L, and Fe^ 2＋ 1.7 mmol/L） the average total organic carbon （TOC） and color removal ratios were 39.3% and 69.5% after 35 min of reaction, respectively. Results from Zahn-Wallens Test also represented that Fenton process was effective to enhance the biodegradability of the test wastewater. As for the further purification of MBR process, TOC removal capacity was examined at different hydraulic retention times （HRT） of 10, 18 and 25 hr. Under the optimum HRT of 18 hr, the average TOC concentration and color of the final MBR effluent were 16.8 mg/L and 2 dilution time, respectively. The sludge yield coefficient was 0.13 g MLSS/g TOC and TOC degradation rate was 0.078 kg TOC/（m ^3 ·day）. The final effluent of MBR can meet the reuse criteria of urban recycling water – water quality standard for miscellaneous water consumption GBT18920-2002.

Advanced treatment of biologically pretreated coal gasification wastewater by a novel heterogeneous Fenton oxidation process

Sewage sludge from a biological wastewater treatment plant was converted into sewage sludge based activated carbon（SBAC） with Zn Cl2 as activation agent, which was used as a support for ferric oxides to form a catalyst（Fe Ox/SBAC） by a simple impregnation method.The new material was then used to improve the performance of Fenton oxidation of real biologically pretreated coal gasification wastewater（CGW）. The results indicated that the prepared Fe Ox/SBAC significantly enhanced the pollutant removal performance in the Fenton process, so that the treated wastewater was more biodegradable and less toxic. The best performance was obtained over a wide p H range from 2 to 7, temperature 30°C, 15 mg/L of H2O2 and 1 g/L of catalyst, and the treated effluent concentrations of COD, total phenols,BOD5 and TOC all met the discharge limits in China. Meanwhile, on the basis of significant inhibition by a radical scavenger in the heterogeneous Fenton process as well as the evolution of FT-IR spectra of pollutant-saturated Fe Ox/BAC with and without H2O2, it was deduced that the catalytic activity was responsible for generating hydroxyl radicals, and a possible reaction pathway and interface mechanism were proposed. Moreover, Fe Ox/SBAC showed superior stability over five successive oxidation runs. Thus, heterogeneous Fenton oxidation of biologically pretreated CGW by Fe Ox/SBAC, with the advantages of being economical, efficient and sustainable, holds promise for engineering application.

Feasibility of bioleaching combined with Fenton oxidation to improve sewage sludge dewaterability

A novel joint method of bioleaching with Fenton oxidation was applied to condition sewage sludge. The specific resistance to filtration（SRF） and moisture of sludge cake（MSC） were adopted to evaluate the improvement of sludge dewaterability. After 2-day bioleaching, the sludge p H dropped to about 2.5 which satisfied the acidic condition for Fenton oxidation.Meanwhile, the SRF declined from 6.45 × 1010 to 2.07 × 1010s2/g, and MSC decreased from91.42% to 87.66%. The bioleached sludge was further conditioned with Fenton oxidation. From an economical point of view, the optimal dosages of H2O2 and Fe2＋were 0.12 and 0.036 mol/L,respectively, and the optimal reaction time was 60 min. Under optimal conditions, SRF,volatile solids reduction, and MSC were 3.43 × 108s2/g, 36.93%, and 79.58%, respectively. The stability and settleability of sewage sludge were both improved significantly. Besides,the results indicated that bioleaching-Fenton oxidation was more efficient in dewatering the sewage sludge than traditional Fenton oxidation. The sludge conditioning mechanisms by bioleaching-Fenton oxidation might mainly include the flocculation effects and the releases of extracellular polymeric substances–bound water and intercellular water.

Enhanced bioremediation of oil contaminated soil by graded modified Fenton oxidation

Graded modified Fenton’s （MF） oxidation is a strategy in which H 2 O 2 is added intermittently to prevent a sharp temperature increase and undesired soil sterilization at soil circumneutral pH versus adding the same amount of H 2 O 2 continuously.The primary objective of the present study was to investigate whether a mild MF pre-oxidation such as a stepwise addition of H 2 O 2 can prevent sterilization and achieve a maximum degradation of tank oil in soil.Optimization experiments of graded MF oxidation were conducted using citric acid,oxalic acid and SOLV-X as iron chelators under different frequencies of H 2 O 2 addition.The results indicated that the activity order of iron chelates decreased as：citric acid （51%） SOLV-X （44%） oxalic acid （9%）,and citric acid was found to be an optimized iron chelating agent of graded MF oxidation.Three-time addition of H 2 O 2 was found to be favorable and economical due to decreasing total petroleum hydrocarbon removal from three time addition （51%） to five time addition （59%）.Biological experiments were conducted after graded MF oxidation of tank oil completed under optimum conditions mentioned above.After graded oxidation,substantially higher increase （31%） in microbial activity was observed with excessive H 2 O 2 （1470 mmol/L,the mol ratio of H 2 O 2：Fe 2＋ was 210：1） than that of non-oxidized soil.Removal efficiency of tank oil was up to 93% after four weeks.Especially,the oil fraction （C 10 –C 40 ） became more biodagradable after graded MF oxidation than its absence.Therefore,graded MF oxidation is a mild pretreatment to achieve an effective bioremediation of oil contaminated soil.

Degradation of refractory organics in concentrated leachate by the Fenton process: Central composite design for process optimization

The primary aim of this study is inert COD removal from leachate nanofiltration concentrate because of its high concentration of resistant organic pollutants.Within this framework,this study focuses on the treatability of leachate nanofiltration concentrate through Fenton oxidation and optimization of process parameters to reach the maximum pollutant removal by using response surface methodology(RSM).Initial pH,Fe2+concentration,H_(2)O_(2)/Fe^(2+)molar ratio and oxidation time are selected as the independent variables,whereas total COD,color,inert COD and UV254 removal are selected as the responses.According to the ANOVA results,the R^(2) values of all responses are found to be over 95%.Under the optimum conditions determined by the model(pH:3.99,Fe^(2+):150 mmol/L,H_(2)O_(2)/Fe^(2+):3.27 and oxidation time:84.8 min),the maximum COD removal efficiency is determined as 91.4%by the model.The color,inert COD and UV254 removal efficiencies are determined to be 99.9%,97.2%and 99.5%,respectively,by the model,whereas the total COD,color,inert COD and UV254 removal efficiencies are found respectively to be 90%,96.5%,95.3%and 97.2%,experimentally under the optimum operating conditions.The Fenton process improves the biodegradability of the leachate NF concentrate,increasing the BOD5/COD ratio from the value of 0.04 to the value of 0.4.The operational cost of the process is calculated to be 0.238€/g COD_(removed).The results indicate that the Fenton oxidation process is an efficient and economical technology in improvement of the biological degradability of leachate nanofiltration concentrate and in removal of resistant organic pollutants.

Effect of phosphate on heterogeneous Fenton oxidation of catechol by nano-Fe_(3)O_(4):Inhibitor or stabilizer?

The effect of phosphate on adsorption and oxidation of catechol, 1,2-dihydroxybenzene,in a heterogeneous Fenton system was investigated. In situ attenuated total reflectance infrared spectroscopy（ATR-FTIR） was used to monitor the surface speciation at the nano-Fe_3O_4 catalyst surface. The presence of phosphate decreased the removal rate of catechol and the abatement of dissolved organic compounds, as well as the decomposition of H2O2. This effect of phosphate was mainly due to its strong reaction with surface sites on the iron oxide catalyst. At neutral and acid pH, phosphate could displace the adsorbed catechol from the surface of catalyst and also could compete for surface sites with H2O2. In situ IR spectra indicated the formation of iron phosphate precipitation at the catalyst surface. The iron phosphate surface species may affect the amount of iron atoms taking part in the catalytic decomposition of H2O2 and formation of hydroxyl radicals,and inhibit the catalytic ability of Fe3O4 catalyst. Therefore, phosphate ions worked as stabilizer and inhibitor in a heterogeneous Fenton reaction at the same time, in effect leading to an increase in oxidation efficiency in this study. However, before use of phosphate as pH buffer or H2O2 stabilizer in a heterogeneous Fenton system, the possible inhibitory effect of phosphate on the actual removal of organic pollutants should be fully considered.

Fenton oxidation of 2,4- and 2,6-dinitrotoluene and acetone inhibition

The performances and kinetic parameters of Fenton oxidation of 2,4-and 2,6-dinitrotoluene(DNT)in water-acetone mixtures and explosive contaminated soil washing-out solutions were investigated at a laboratory scale.The experimental results show that acetone can be a significant hydroxyl radical scavenger and result in serious inhibition of Fenton oxidation of 2,4-and 2,6-DNT.Although no serious inhibition was found in contaminated soil washing-out solutions,longer reaction time was needed to remove 2,4-and 2,6-DNT completely,mainly due to the competition of hydroxyl radicals.Fenton oxidation of 2,4-and 2,6-DNT fit well with the first-order kinetics and the presence of acetone also reduced DNT’s degradation kinetics.Based on the comparison and matching of retention time and ultraviolet(UV)spectra between high performance liquid chromatography(HPLC)and standards,the following reaction pathway for 2,4-DNT primary degradation was proposed:2,4-DNT→2,4-dinitro-benzaldehyde→2,4-dinitrobenzoic acid→1,3-dinitrobenzene→3-nitrophenol.

Enhancement of Fenton oxidation for removing organic matter from hypersaline solution by accelerating ferric system with hydroxylamine hydrochloride and benzoquinone

Fenton oxidation is generally inhibited in the presence of a high concentration of chloride ions.This study investigated the feasibility of using benzoquinone（BQ） and hydroxylamine hydrochloride（HA） as Fenton enhancers for the removal of glycerin from saline water under ambient temperature by accelerating the ferric system.It was found that organics removal was not obviously affected by chloride ions of low concentration（less than 0.1 mol/L）,while the mineralization rate was strongly inhibited in the presence of a large amount of chloride ions.In addition,ferric hydrolysis-precipitation was significantly alleviated in the presence of HA and BQ,and HA was more effective in reducing ferric ions into ferrous ions than HA,while the H_2O_2 decomposition rate was higher in the BQ-Fenton system.Electron spin resonance analysis revealed that OH production was reduced in high salinity conditions,while it was enhanced after the addition of HA and BQ（especially HA）.This study provided a possible solution to control and alleviate the inhibitory effect of chloride ions on the Fenton process for organics removal.

Fenton treatment via oxidative mechanism and its kinetics on soil polluted with automatic gas oil

The effectiveness,viability and feasibility of applying Fenton reactants in treating soil contaminated with automatic gas oil(AGO)was investigated ex-situ.Soil was simulated to achieve 10%contamination using AGO(diesel)as the primary contaminant.Physicochemical properties and heavy metal contents were characterized using standard analytical methods,while total petroleum hydrocarbon(TPH)content was determined by molecular spectroscopy.An investigation of the soil physicochemical properties shows severe impact of the contaminant on pH,conductivity,phosphorus and(TPH)content.The optimum concentration of Fenton reactants determined from the optimization study was found to be 350,000 ppm H2O2 and 600 ppm FeSO4 at optimum room temperature range of 27e30
C and optimum pH of 4.7.The highly exothermic Fenton oxidation treatment resulted in significant decrease in TPH content by 87.6%after 6 h of periodic monitoring;breaking down the hydrocarbons into non-toxic environmental friendly products.Kinetics analysis and evaluation shows pseudo-first order mechanism for the Fenton treatment with a calculated rate constant of 0.226 h-1 and half life of 3 h 4 min.The Fenton method is found to be very effective and efficient not only for the removal of the diesel contaminant,but also for the restoration of lost physicochemical properties occasioned by the effect of the contaminant.The environmental friendliness and fast response time towards effective clean up gives the technique a cutting edge advantage over other conventional methods.It therefore presents potentials for remediation experts in outright applications on real field challenges.

Fe/C micro electrolysis and Fenton oxidation process for the removal of recalcitrant colored pollutants from mid-stage pulping effluent

The pulp and paper industry produces a large amount of colored effluent in the pulping,bleaching,and papermaking processes.The wastewater from the pulp washing and bleaching stages is also known as mid-stage pulping effluent,which is difficult to treat due to its toxicity and dark dolor.This paper reports a novel Fe/C micro-electrolysis process for the treatment of the mid-stage pulping effluent.Results show that this process is effective in removing the color under optimal reaction conditions.Scanning electron microscopy(SEM)and Fourier transform infrared spectroscopy(FTIR)analyses indicate that the colored pollutants were removed from the wastewater in the Fe/C micro-electrolysis by adsorption,collection and filtration mechanisms.The Fe2+ions produced in the micro-electrolysis process functioned as Fenton’s reagents with H2O2 in the follow-up oxidation stage,which enhanced the removal of chemical oxygen demand(COD)and color.

Relationship between reaction rate constants of organic pollutants and their molecular descriptors during Fenton oxidation and in situ formed ferric-oxyhydroxides

Fenton oxidation is a promising water treatment method to degrade organic pollutants. In this study, 30 different organic compounds were selected and their reaction rate constants（k） were determined for the Fenton oxidation process. Gaussian09 and Material Studio software sets were used to carry out calculations and obtain values of 10 different molecular descriptors for each studied compound. Ferric-oxyhydroxide coagulation experiments were conducted to determine the coagulation percentage. Based upon the adsorption capacity,all of the investigated organic compounds were divided into two groups（Group A and Group B）. The percentage adsorption of organic compounds in Group A was less than 15%（wt./wt.）and that in the Group B was higher than 15%（wt./wt.）. For Group A, removal of the compounds by oxidation was the dominant process while for Group B, removal by both oxidation and coagulation（as a synergistic process） took place. Results showed that the relationship between the rate constants（k values） and the molecular descriptors of Group A was more pronounced than for Group B compounds. For the oxidation-dominated process,EHOMOand Fukui indices（f（0）_x, f（-）_x, f（＋）_x） were the most significant factors. The influence of bond order was more significant for the synergistic process of oxidation and coagulation than for the oxidation-dominated process. The influences of all other molecular descriptors on the synergistic process were weaker than on the oxidation-dominated process.