Oxidation of Partially Hydrolyzed Polyacrylamide from Polymer Flooding Processes Using Fenton Reagents

The degradation of partially hydrolyzed polyacrylamide(HPAM) found in alkaline/surfactant/polymer flooding sewage was investigated using Fenton-type reagents. Different Fenton reagent treatments for HPAM degradation were compared. The effects of pH, hydrogen peroxide(H_(2)O_(2)), ferrous ion(Fe^(2+)), and tartaric ion(C_(4)H_(4)O_(6)^(2-)) concentrations were studied. The degradation reaction occurred within a wide range of pH(3–9). The HPAM degradation performance of photo-Fenton processes using solar light and UV were compared with that of the Fenton process. The degradation rate was found to be strongly dependent on the H_(2)O_(2)/Fe^(2+)/C_(4)H_(4)O_(6)^(2-)molar ratio. The HPAM degradation efficiency was 90%, and the chemical oxygen demand removal efficiency was 85%. HPAM could be degraded into a compound with a lower molecular weight, but it was difficult to achieve complete mineralization to CO_(2). The presence of intermediate products hindered further oxidation in the Fenton process.

Exploitation of Fenton and Fenton-like reagents as alternative conditioners for alum sludge conditioning

The use of Fenton＇s reagent （Fe^2＋/H2O2） and Fenton-like reagents containing transition metals of Cu（Ⅱ）, Zn（Ⅱ）, Co（Ⅱ）, and Mn（Ⅱ） for an alum sludge conditioning to improve its dewaterability was investigated. The results obtained were compared with those obtained from conditioning the same alum sludge using cationic and anionic polymers. Experimental results show that Fenton＇s reagent was the best among the Fenton and Fenton-like reagents for the alum sludge conditioning. A considerable effectiveness of capillary suction time （CST） reduction efficiency of 47% can be achieved under test conditions of Fe^2＋/H2O2 = 20/125 mg/g DS （dry solid） and pH 6.0. The observation of floc-like particles after Fenton＇s reagent conditioning of alum sludge suggested that the mechanism of Fenton＇s reagent conditioning was different from that of polymer conditioning. In spite of the lower efficiency in the CST reduction of Fenton＇s reagent in alum sludge conditioning compared to that of polymer conditioning, Fenton＇s reagent offers a more environmentally safe option. Tiffs study provided an example of proactive treatment engineering, which is aimed at seeking a safe alternative to the use of polymers in sludge conditioning towards achieving a more sustainable sludge management strategy.

Degradation of Silicone Rubbers in Fenton's Reagents

Gaskets are applied in PEMFCs（proton exchange membrane fuel cells） to keep reactant gases and liquid within their respective regions, which are of great significance for the both sealing and electrochemical performance of fuel cells during the long-term operation. In this study, the degradation of silicone rubbers, often selected as seals in PEMFCs, in Fenton＇s reagents with different H_2O_2 concentrations was investigated. The changes in chemical properties, mechanical behavior and surface morphology of the samples were studied before and after exposure to the test environment over time. It is found that increasing H_2O_2 concentration will degrade the rubbers more severely. The experimental results elucidate the degradation mechanism of silicone rubbers in Fenton＇s reagents and the influence of H_2O_2 in the degradation process.

Degradation of polyvinyl-alcohol wastewater by Fenton’s reagent: Condition optimization and enhanced biodegradability

The pretreatment of refractory polyvinyl-alcohol （PVA） wastewater with low value of CODcr by Fenton＇s reagent was investigated to enhance the biodegradabilily. The effects of operating conditions such as pH of the solution, Fe2＋ dosage, H2O2 dosage, reaction time and initial PVA concentration on the removal efficiency of CODCr were discussed. It is demonstrated that the optimum value of pH for removal of CODcr is 5 and the most suitable dosages of H2O2 （2%） and FeSO4 （10 mg/L） are 5% and 8.0%, respectively. When the initial CODcr value of the PVA water is 760 mg/L, the favorable reaction time is 110 min. Under these optimum conditions, the removal ratio of CODcr is 58.6% 61.4%, and the value of biodegradability （CODB/CODcr） increases markedly from 8.9% 9.7% to 62.6% 68.3%.

Treatment of Landfill Leachate by Fenton Oxidation Process

Central composite design (CCD), the most popular design ofresponse surface methodology (RSM), was employed to investigate theeffect of total organic carbon (TOC) ratio of high molecular weightorganic matter (HMW) to low molecular weight organic matter (LMW),the LMW strength and molar ratio of hydrogen peroxide to ferrous ionon landfill leachate treatment by Fenton process. Based on theexperimental data, a response surface quadratic model in terms ofactual factors was obtained through analysis of variance (ANOVA).

Degradation of 4-Chlorophenol Solution by Synergetic Effect of Dual-frequency Ultrasound with Fenton Reagent

4-Chlorophenol (4-CP) solution was treated by dual-frequency ultrasound inconjunction with Fenton reagent, and obvious improvement in the 4-CP degradation rate was observedin this advanced oxidation process. Experimental results showed that ultrasonic intensity,saturating gas and pH value affected greatly the 4-CP removal rate. Among four different saturatinggases (Ar, O_2, air and N_2), 4-CP degradation with Ar-saturated solution was the best. However, inthe view of practical wastewater treatment, using oxygen as the saturating gas would be moreeconomical. The addition of Fenton reagent followed the first-order kinetics and increased the 4-CPdegradation rate. The 4-CP removal rate increased by around 126% within 15 min treatment. Thesynergetic effect of dual-frequency ultrasound with Fenton reagent on 4-CP degradation was obviouslyobserved.

2-chlorophenol oxidation kinetic by photo-ssisted Fenton process

Experimental data are presented to test and validate a kinetic model for the oxidation of 2 chlorophenol wastewater by photo assisted Fenton process. The data showed that this process had produced good effects under acidic conductions. Up to 90% 2 chlorophenol was removed after 90 minute reaction time with H 2O 2 of 25% COD Cr, in , while in UV/H 2O 2 system only 16 8% 2 chlorophenol was removed after one hour treatment. The optimal pH in this reaction occurred between pH 3 0 and pH 4.0. The reaction kinetics for photo assisted Fenton process experimented in this research was investigated. Kinetic models were proposed for the treatment of 2 chlorophenol wastewater. The reaction was found to follow the 2nd order. The equations of reaction kinetics are as follows:-d[RH]d t = K RH [RH][H 2O 2] 0exp (-K H 2O 2 t );-d[COD Cr ]d t = K COD Cr [COD Cr ][H 2O 2] 0exp(-K′ t ). The prediction of the models was found to be in a good agreement with experimental results, thus confirming the proposed reaction mechanism.

Catalytic oxidation degradation of phenol in wastewater by heterogeneous Fenton reagent

Heterogeneous Fenton reagent, as a strong oxidizer, has been used widely in the treatment ofwastewater. We prepared Fe2O3/γ-Al2O3 catalyst by impregnation method and characterized it by powder X-ray diffraction （XRD） and X-ray photoelectron spectroscopy （XPS）, scanning electron microscopy （SEM）. Test results show that Fe203 crystal was compounded on the γ-Al2O3 carder. We tested and optimized Fe203/γ-Al2O3 /H2O2 and Fe2O3/γ-Al2O3 /H2O2/UV processes to remediate organic material of phenol, using phenol solution with an in. itial concentration of 250 mg/L as a representative of phenolic industrial Wastewater. The preparation conditions were optimized based on performance of Fe2Oa/γ-Al2O3 catalyst and the processes to degrade phenol in aqueous environments. The experimental results showed that the phenol removal perfomance with Fe2O3/γ-Al2O3 /H2O2/UV was more complete than with Fe2O3/γ-Al2O3 /H2O2 and degradation rate of phenol reached 89.4% and 94.7% respectively after reaction for2 h.

Treatment of Wastewater from Pharmaceutical Intermittent Production by Fe/C-Fenton-Hydrolysis Acidification-A/O Process

The design and running effect of treatment of wastewater from pharmaceutical intermittent production by iron-carbon（Fe/C）-Fentonhydrolysis acidification-anoxic/aerobic（A/O）process were introduced.The results of continuous operation showed that when the flow rate of the influent wastewater was 300 m^3/d,after the influent high-concentration wastewater（CODCrand NH4＋-N concentration were 35 000 and 1 000 mg/L,respectively）and medium-concentration wastewater（CODCrand NH4＋-N concentration were 1 500 and 100 mg/L,respectively）were treated by the process,CODCrand NH4＋-N concentration in the effluent decreased to 360-410 and 20-25 mg/L,respectively,and the quality of the effluent could meet the Grade III standard of Integrated Wastewater Discharge Standard（GB 8978-1996）.The combined process was proved to be an effective method to treat wastewater from pharmaceutical intermittent production,and its operation was stable.

Sonolysis and mineralization of pentachlorophenol by means of varying parameters

Degradation effect of organic pollutant on pentachlorophenol(PCP) is researched by ultrasound. PCP is treated by low frequency(16 kHz) and high frequency(800±1 kHz), and bi frequency. The results of investigation on the ultrasonic destruction of PCP showed that the rate of PCP degradation at the same conditions is the highest at bi frequency, and the lowest at 16 kHz. In the presence of Fenton type reagent the degradation rate of PCP is the highest at bi frequency(20 93 times) as compared to the stirring system. This ratio is 4 91 and 1 06 at 800 kHz and 16 kHz, respectively. The studies showed the bi frequency is an effective method for pollutants degradation, but it is need make further study. Taking 800 kHz for example, under the same conditions, the smaller pH of the solution, the higher is the reaction rate. A similar situation applied to TOC, but the TOC removal lags behind degradation of PCP. This indicated the PCP is not completely mineralized. The ultrasound is somewhat enhanced for degradation of PCP and mineralization with only addition of CuSO 4, but the combination of ultrasound and Fenton type reagent is effective method for PCP degradation and mineralization. The rate of PCP degradation and TOC removal appeared to follow pseudo first order reaction kinetic law.

LPWCO method for the treatment of high concentrated organic wastewater

Based on wet air oxidation (WAO) and Fenton reagent, this paper raised a new low pressure wet catalytic oxidation (LPWCO) which requires low pressure for the treatment of highly concentrated and refractory organic wastewater. Compared with general wet air oxidation, the pressure of the treatment(0 1—0 6MPa) is only one of tens to percentage of latter (3 5—10MPa). In addition, its temperature is no more than 180℃. Compared with Fenton reagent, while H 2O 2/COD(weight ratio) is less than 1 2, the removal of COD in the treatment is over twenty percents more than Fenton's even the value of COD is more than 14000mg/L. In this paper, the effect factor of COD removal and the mechanism of this treatment were studied. The existence of synergistic effect (catalytic oxidation and carbonization) for COD removal in H 2SO 4 Fenton reagent system under the condition of applied pressure and heating (0 1—0 6MPa, 104—165℃) was verified. The best condition of this disposal are as follows: H 2O 2/COD (weight ratio)=0 2—1 0, Fe 2+ 0 6×10 -3 mol, H 2SO 4 0 5mol, COD>1×10 4mg/L, the operating pressure is 0 1—0 6MPa and temperature is 104—165℃. This method suits to dispose the high concentrated refractory wastewater, especially to the wastewater containing H 2SO 4 produced in the manufacture of pesticide, dyestuff and petrochemical works.

Direct Synthesis,Characterization and Catalytic Performance of Iron-Containing SBA-15 for Phenol Degradation

An iron-containing SBA-15（Fe-SBA-15） has been synthesized via one-pot hydrothermal method under weak acidic conditions. A series of characterizations show nanocomposite materials of iron particles supported over mesostructured materials. The catalytic activity of these iron-containing SBA-15 materials has been tested for the heterogeneous Fenton degradation of phenolic aqueous solutions. The catalytic performance has beta monitored in terms of phenol conversion, whereas the catalytic stability was evaluated by catalyst recycle. The influence of concentration of hydrogen peroxide, catalyst loading, catalyst prepared with different Fe/Si molar ratios in the gel and pH values of the solution on phenol conversion has been studied. Achieving a good catalytic performance accompanied with a noteworthy stability, Fe-SBA-15 materials prepared by this method are shown as the successful catalyst for degradation of phenolic aqueous solutions by Fenton process.

Segregation Treatment and Resource Recycling of Enteric Coating and Heparin Sodium Manufacturing Wastewater

Firstly, the water-quality characteristics of intestinal lavage wastewater and enzymolysis wastewater from the typical heparin sodium pro- ductive process were analyzed, and then the segregation treatment was applied in the treatment of enteric coating and heparin sodium manufacturing wastewater. Finally, the treatment of the two kinds of wastewater by different methods were discussed. The results showed that, COD of enzymolysis wastewater treated by centrifugation-coagulation-Fenton reagent oxidation-adsorption process was lower than 100 mg/L, while intestinal lavage wastewater treated by coagulation-ASBR-SBR process could meet the first standard of Comprehensive Discharge Standard of Sewage （GB8978-1996） after one month of continuous operation.

用于实现高性能热催化氧化还原反应的二茂铁功能化锆氧簇

The Zr(Ⅳ)ions are easily hydrolyzed to form oxides,which severely limits the discovery of new structures and applications of Zr-based compounds.In this work,three ferrocene(Fc)-functionalized Zr-oxo clusters(ZrOCs),Zr_(9)Fc_(6),Zr_(10)Fc_(6) and Zr_(12)Fc_(8) were synthesized through inhibiting the hydrolysis of Zr(Ⅳ)ions,which show increased nuclearity and regular structural variation.More importantly,these Fc-functionalized ZrOCs were used as heterogeneous catalysts for the transfer hydrogenation of levulinic acid(LA)and phenol oxidation reactions for the first time,and displayed outstanding catalytic activity.In particular,Zr_(12)Fc_(8) with the largest number of Zr active sites and Fc groups can achieve>95% yield for LAto-c-valerolactone within 4 h(130℃)and>98% yield for 2,3,6-trimethylphenol-to-2,3,5-trimethyl-pbenzoquinone within 30 min(80℃),showing the best catalytic performance.Catalytic characterization combined with theory calculations reveal that in the Fc-functionalized ZrOCs,the Zr active sites could serve as substrate adsorption sites,while the Fc groups could act as hydrogen transfer reagent or Fenton reagent,and thus achieve effectively intramolecular metal-ligand synergistic catalysis.This work develops functionalized ZrOCs as catalysts for thermal-triggered redox reactions.

Fenton process for degradation of selected chlorinated aliphatic hydrocarbons exemplified by trichloroethylene,1,1-dichloroethylene and chloroform

The degradation of selected chlorinated aliphatic hydrocarbons(CAHs)exemplified by trichloroethylene(TCE),1,1-dichloroethylene(DCE),and chloroform(CF)was investigated with Fenton oxidation process.The results indicate that the degradation rate was primarily affected by the chemical structures of organic contaminants.Hydroxyl radicals(·OH)preferred to attack the organic contaminants with an electron-rich structure such as chlorinated alkenes(i.e.,TCE and DCE).The dosing mode of Fenton’s reagent,particularly of Fe^(2+),significantly affected the degradation efficiency of studied organic compound.A new“time-squared”kinetic model,C=C_(oexp)(-k_(obst)^(2)),was developed to express the degradation kinetics of selected CAHs.This model was applicable to TCE and DCE,but inapplicable to CF due to their varied reaction rate constants towards·OH.Chloride release was monitored to examine the degree of dechlorination during the oxidation of selected CAHs.TCE was more easily dechlorinated than DCE and CF.Dichloroacetic acid(DCAA)was identified as the major reaction intermediate in the oxidation of TCE,which could be completely removed as the reaction proceeded.No reaction intermediates or byproducts were identified in the oxidation of DCE and CF.Based on the identified intermediate,the reaction mechanism of TCE with Fenton’s reagent was proposed.

Self-catalytic degradation of ortho-chlorophenol with Fenton's reagent studied by chemiluminescence

The degradation of ortho-chlorophenol using Fenton＇s reagent was studied by chemiluminescence （CL）. Without a special CL reagent, a weak CL emission from the mixture of ferrous ion and hydrogen peroxide was observed at room temperature. The CL intensity was increased by the addition of ortho-chlorophenol into the mixed solution. When the temperature was raised to 65°C, the CL intensity was enhanced strongly. The CL mechanisms for the system H2O2-Fe2＋ with and without ortho-chlorophenol were studied by examining the CL spectrum, gas chromatography-mass spectrometry and electron spin resonance spectrum. The effects of various free radical scavengers, surfactants and fluorescence compounds on the CL intensity were also investigated. A self-catalytic oxidation mechanism was proposed. The results showed that singlet oxygen was the main emitter for the system H2O2-Fe2＋. The strong CL from the system H2O2-Fe2＋-ortho-chlorophenol was due to singlet oxygen and electronically excited quinone. The benzenediol-like intermediate product formed during the phenol oxidation process greatly promoted the Fenton＇s reaction and led to higher CL intensity. Chemiluninescence is a novel approach for the investigation of the oxidation of some organic pollutants by Fenton＇s reagent.