A combined process coupling an electro-Fenton pretreatment and a biological degradation was implemented in order to mineralize synthetic and industrial pharmaceutical effluents, containing a veterinary antibiotic, sulfamethazine (SMT). The electro-Fenton pretreatment of an SMT synthetic solution was first examined and the obtained results showed total SMT degradation after 30 min of electrolysis at pH 3, 18 °C, 500 mA and an initial SMT concentration of 0.2 mM, while the level of mineralization remained low (2.1 and 18.1% for electrolysis times of 30 and 60 min), ensuring significant residual organic content for a subsequent biological treatment. In a second part, biological treatments were performed to complete the mineralization of the electrolyzed solutions of SMT, showing a significant level of mineralization after about 18 days of culture, 61.4% for a 30-min pretreatment. The same electrolysis conditions were then applied to the pretreatment of an industrial pharmaceutical effluent, showing a total SMT removal in the effluent after 100 min of electrolysis, while the mineralization yield remained also low (7.5%), showing the formation of organic intermediate products. Fortunately, the mineralization yield during the subsequent biological treatment increased to almost 80%, namely an overall yield of 81.4%. Consequently, the integrated electro-Fenton biological treatment process proved to be an efficient technology to reprocess industrial pharmaceutical effluents. 相似文献
The electro-Fenton process is an electrochemical method for wastewater treatment based on the production of hydroxyl radicals via H2O2 generation in the presence of ferrous ions. The aim of this work is to show the use of a new mineral iron dosage source (goethite, α-FeOOH) for electro-Fenton process that achieves a more efficient mineralization treatment. Our new proposed Goethite catalyzed electro-Fenton (GEF) process yields 95% of mineralization for an organic model pollutant such as aniline under optimum standard electro-Fenton (SEF) conditions. For that, GEF process uses only 2 ppm of soluble iron, compared with the 55 ppm of soluble iron used by SEF process. In order to show the potential scope of GEF process, the effect of goethite concentration, solution conductivity, solution pH, temperature, and applied current density are studied in detail. 相似文献
Sulfamethoxazole (SMX) is a synthetic antibiotic widely applied as a bacteriostatic drug to treat a number of diseases. SMX can persist in the environment for long periods of time because of its low biodegradability, which may result in various, direct and indirect, toxicological effects on the environment and on human health. Therefore, we have developed the electrochemical advanced oxidation process (AOP) “electro-Fenton” to degrade SMX in aqueous media. In this work, a detailed study of the evolution of toxicity of SMX and its degradation products in aqueous solutions, during treatment by the electro-Fenton AOP, is described, using the bioluminescence Microtox® method, based on the inhibition of luminescence of marine bacteria Vibrio fischeri. Samples were collected at various electrolysis times and analyzed by HPLC for quantifying the evolution of the degradation products, and their toxicity was measured by the Microtox® method. Our results demonstrated that the toxicity of SMX aqueous solutions varied considerably with the electrolysis time and the applied current intensity. This phenomenon could be explained by the formation and disappearance of several degradation products, including cyclic and/or aromatic intermediates, and short-chain acid carboxylic acids, having a toxicity different of the initial antibiotic. The curves of the % of bacterial luminescence inhibition vs. electrolysis time, corresponding to the evolution of the toxicity of the formed degradation products, were investigated and tentatively interpreted.
Figure Effect of the applied electrolysis current intensity on the evolution of the V. fischeri bacteria luminescence inhibition with time during the electro-Fenton process of SMX aqueous solutions, after an exposure time of 15 min
The electrochemical oxidation of vanillic acid (VA) in acetone–water mixtures, was studied by electro-Fenton (EF) process in an undivided electro-chemical cell equipped with a carbon fiber cloth as cathode and Pt anode. The objective was the conversion of VA into protocatechuic acid (PCA) well known by its high added value. To our knowledge, the EF method was not used in organic electrosynthesis. The influence of several operating parameters, such as applied current, initial VA concentration and volumic percentage of acetone was investigated. The evolution of the concentrations of VA and its main oxidation product PCA during electrolyses was monitored by means of high performance liquid chromatography (HPLC). The experimental data indicated that the kinetics of VA disappearance follow a pseudo first and zero orders for initial VA concentrations respectively equals to 6.5 and (10, 20, 30) mmol L−1. The maximum PCA concentration increases with volumic percentage of acetone and initial VA concentration. Under optimal experimental conditions of applied current (20 mA) and volumetric percentage of acetone (20%), the increase in the initial VA concentration leads to a linear increase in the maximum of PCA concentration. The very good selectivity rate of the oxidation of VA to PCA by the EF process, was interpreted by the stabilizing effects of acetone and especially the complexation of PCA by the iron ions. 相似文献
This paper studies the degradation of methiocarb, a highly hazardous pesticide found in waters and wastewaters, through an electro-Fenton process, using a boron-doped diamond anode and a carbon felt cathode; and evaluates its potential to reduce toxicity towards the model organism Daphnia magna. The influence of applied current density and type and concentration of added iron source, Fe2(SO4)3·5H2O or FeCl3·6H2O, is assessed in the degradation experiments of methiocarb aqueous solutions. The experimental results show that electro-Fenton can be successfully used to degrade methiocarb and to reduce its high toxicity towards D. magna. Total methiocarb removal is achieved at the applied electric charge of 90 C, and a 450× reduction in the acute toxicity towards D. magna, on average, from approximately 900 toxic units to 2 toxic units, is observed at the end of the experiments. No significant differences are found between the two iron sources studied. At the lowest applied anodic current density, 12.5 A m−2, an increase in iron concentration led to lower methiocarb removal rates, but the opposite is found at the highest applied current densities. The highest organic carbon removal is obtained at the lowest applied current density and added iron concentration. 相似文献
In this work, the degradation and mineralization of toluene (TOL) in synthetic wastewater were studied by electro-Fenton process in a batch reactor. Also the impact of operational factors such as applied current, electrolysis time, concentration of TOL and Ferrous ion have been explored on the removal of toluene. In optimum conditions, the removal efficiency of TOL and total organic carbon (TOC) were 94.5 and 32.3% after 60 min of reaction. Based on the kinetic study the pseudo first-order rate constant for the removal of toluene and TOC was obtained at k = 5.90 × 10?2 and 9.8 × 10?3 min?1, respectively. 相似文献
Anolyte solution produced by membrane electrolysis of NaCl solution contains a high level of available chlorine content (ACC) and other oxidizing compounds, rendering this solution a strong disinfectant property. In this paper, some process parameters affecting the anolyte production efficiency, such as total inlet flow (240–320 L/h), saline solution concentration (1.65–3.50 g/L), and the type of membrane (cation exchange, anion exchange, and bipolar membranes) were investigated in an electrolysis cell. Changes in the quality of anolytes produced at three initial concentrations of very high (ACC1 = 816.5 mg/L), relatively high (ACC2 = 461.5 mg/L), and medium (ACC3 = 355.0 mg/L) during storage (from the production up to 20 weeks) were examined by adjusting the total inlet flow, saline concentrations, and membrane types. Changes in the ACC of the produced anolyte solution were generally affected by the type of membrane used in the electrolysis cell. The use of anion exchange membrane resulted in the lowest durability of anolyte quality (60–80% ACC reduction after 4 weeks of storage) and the cation exchange membrane had the highest durability (less than 40% decrease after 4 weeks of storage). In addition, changes in the pH and the oxidation–reduction potential of the anolyte were investigated during the storage period, which had a different trend depending on the type of applied membrane. 相似文献
The electrochemical removal of tramadol hydrochloride from aqueous solutions has been investigated under several operating conditions using a Pb/PbO2 electrode. The optimum conditions of the treatment process are: current density of 1000 mA/cm−2, pH ≈6, temperature of 10 °C and initial tramadol hydrochloride concentration of 100 mg/L. The time of electrolysis is 25 min for degradation rate of tramadol hydrochloride and chemical oxygen demeaned (COD) removal is 22 h. The results were obtained by UV–Vis spectrophotometer and the presently designed electrode was coincident. 相似文献
This research aimed to optimize and model the adsorption process of oil layer removal using activated plantain peels fiber (PPF), a biomass-based material. The adsorbent was activated by thermal and esterification methods using human and environmentally friendly organic acid. Effects of process parameters were examined by one factor at a time (OFAT) batch adsorption studies, revealing optimal conditions for oil removal. Also, RSM, ANN and ANFIS were used to adequately predict the oil removal with correlation coefficient > 0.98. RSM modelling revealed the best conditions as 90 °C, 0.2 mg/l, 1.5 g, 6 and 75 mins, for temperature, oil–water ratio, adsorbent dosage, pH and contact time respectively. Under these simulated conditions, the predicted oil removal was 96.88 %, which was experimentally validated as 97.44 %. Thermodynamic studies revealed the activation energy, change in enthalpy and change in entropy for irreversible pseudo-first order and pseudo-second order model as (15.82, 24.17, ?0.614 KJ/mols) and (33.21,40.31, ?0.106 KJ/mols) respectively, indicating non-spontaneous process; while modeling studies revealed that the adsorption process was highly matched to Langmuir’s isotherm, with maximum adsorption capacity of 50.34 mg/g. At the end of the overall statistical modelling, ANFIS performed marginally better than the ANN and RSM. It can be concluded from these results that our biomass-based material is an efficient, economically viable and sustainable adsorbent for oil removal, and has potentials for commercialization since the process of adsorption highly matched with standard models, and its capacity or percentage oil removal also compares favorably to that of commercially available adsorbents. 相似文献
Colour and COD removals of the azo dyes Congo Red (CR) and Reactive Black 5 (RB5) were individually evaluated in a sequential
anaerobic/aerobic treatment system. Additionally, dye toxicity was assessed by using acute ecotoxicity tests with Daphnia magna as the indicator-organism. The anaerobic reactor was operated at approximately 27 °C and with hydraulic retention times of
12 and 24 h. The aerobic reactor was operated in batch mode with a total cycle of 24 h. During anaerobic step, high colour
removals were obtained, 96.3% for CR (400 mg/L) and 75% for RB5 (200 mg/L). During the aerobic phase, COD effluent was considerably
reduced, with an average removal efficiency of 52% for CR and 85% for RB5, which resulted in an overall COD removal of 88%
for both dyes. Ecotoxicity tests with CR revealed that the anaerobic effluent presented a higher toxicity compared with the
influent, and an aerobic post-treatment was not efficient in reducing toxicity. However, the results with RB5 showed that
both anaerobic and aerobic steps could decrease dye toxicity, especially the aerobic phase, which removed completely the toxicity
in D. magna. Therefore, the anaerobic/aerobic treatment is not always effective in detoxifying dye-containing wastewaters, sometimes
even increasing dye toxicity. 相似文献
Visible light irradiation combined with homogeneous iron and/or hydrogen peroxide to degrade organic dye rhodamine B (RhB) and small molecular compound 2,4-dichlorophenol (2,4-DCP) in a home-made bottle reactor was assessed. The concen-tration of oxidize species, Fe3+ and Fe2+ were determined during the degradation process. The results demonstrated that visible light irradiation combined with electro-Fenton improved the degradation efficiency. Moreover, both RhB and 2,4-DCP were mineralized during visible light synergistic electro-Fenton oxidation process. 95.0% TOC (total organic carbon) removal rate of RhB occurred after 90 min and 96.7% of COD (chemical oxygen demand) removal rate after 65 min of irradiation. 91.3% TOC removal rate of 2,4-DCP occurred after 16 h of irradiation and 99.9% COD removal rate occurred after 12 h of illumination. The degradation and oxidation process was dominated by the hydroxyl radical ( · OH) generated in the system. Both the impressed electricity and dye sensitization by visible light facilitated the conversion between Fe3+ and Fe 2+ , thus, improving Fenton reaction efficiency. 相似文献
The photocatalytic degradation of ciprofloxacin was investigated by developing a predictive mathematical model using response surface methodology and an artificial neural network. The four independent variables involve solution pH, reaction time, catalyst dose, and initial antibiotic concentration considered as factors in central composite design to observe the response in the form of antibiotic degradation. Accordingly, at an optimum antibiotic concentration of 5.02 mg/L, catalyst dose of 44.51 mg/L, solution pH of 5.04, and reaction time of 75.80 min, the photocatalysis method achieved a ciprofloxacin degradation of 88.30%. The experimental outputs were very much consistent along with the predicted output of experiments through response surface methodology (R2 = 0.9969) and artificial neural network (R2 = 0.975). The adsorption isotherm and kinetic study reveal that Langmuir isotherm and pseudo-second-order kinetic models respectively were best fitted for degradation of ciprofloxacin through photocatalysis. The finding provides a novel method for evaluating the photocatalysis process for the optimization of ciprofloxacin antibiotic removal from pharmaceutical waste using experiments and computer simulation tools. 相似文献
For the first time, gas-phase electrolysis of HCl to chlorine was conducted in a fuel cell type reactor with an oxygen depolarized cathode. Very low cell voltages below − 1 V at industrially relevant current densities of 4 kA m− 2 were obtained. Compared to technical HCl electrolysis processes, this leads to a reduction in electrical energy demand of approximately 30%. The temperature and the relative humidity (rH) of the cathode inlet gas were identified as key parameters controlling the overall performance of the system. 相似文献
Aiming at the problems of the low grade of rubidium (Rb) in biotite, and long leaching time and low leaching efficiency of Rb in mica ore, the chlorination roasting-assisted ultrasonic enhanced water leaching method was employed to extract Rb from biotite ore in this study. During the chlorination roasting process, the optimal conditions were obtained, namely roasting temperature 900 °C, roasting time 40 min, and the mass ratio of ore to calcium chloride 1:1, the optimum leaching rate was 96.75 %. Compared with conventional leaching, the ultrasonic field could greatly shorten the leaching time and realize fast and efficient leaching of Rb. The optimal conditions for ultrasonic enhanced leaching were: ultrasonic power 100 W, leaching temperature 60 °C, leaching time 20 min, liquid–solid ratio 4:1, the Rb leaching rate was 98.73 %, which was 40 min shorter than conventional leaching. The particle size and SEM results indicated that the samples by ultrasonic leaching were smaller, no agglomeration phenomenon in a large area, and the surface of the samples was relatively smooth. 相似文献
Optimization of electrocoagulation (EC) using copper electrode in terms of Cr(VI) removal from simulated waste water was executed by applying surface methodology and kinetic study. In this research, electrocoagulation process was applied to evaluate the outcome of operational parameters such as initial Cr(VI) concentration, pH, electrode distance, current density and supporting electrolyte (NaCl) concentration for the removal of Cr(VI). The experimental results showed that current density of 41.32 A/m2, electrode distance of 1.4 cm, initial pH of 5.65, time of electrocoagulation of 40 min and initial conductivity 0.21 ms are the optimal operating parameters to attain 93.33% removal efficiency of Cr(VI) ions from simulated waste water. The high value of R2 = 98.15 and R2adj = 96.49 show that fitted model confirms a good agreement with the real and predicted Cr(VI) removal percentage. It was concluded that Cr(VI) ion removal follows the first-order kinetic model by kinetic study of EC process. 相似文献
A novel effective method for preparing polyaluminum chloride (PAC) with high content of Al13 polymer through conventional electrolysis coupled with rare earth Nd-Fe-B magnetic field was introduced. The content of Al13 polymer in PAC synthesized by this method was highly influenced by the electrobath voltage (E), the magnetic flux density (B), the current density (i) and the distance between the two adjacent electrodes (dadj). A total aluminum concentration (AlT) in the PAC solution of 0.8 mol l−1 was obtained when the E, B and i was 2.2 V, 0.4 T and 3.2 A dm−2, respectively. The optimum dadj and circulating flow (Qf) were 20 mm and 23.7 l h−1. With accelerated mass transfer rate by external magnetic field and high Qf, this process had the advantages of forming more Al(OH)4− as the precursor of Al13 polymer and inhibiting the concentration polarization more obviously than conventional electrolysis process. Under the optimum conditions, the amount of Al13 polymer in PAC accounted for 82.3% of the AlT (AlT = 0.8 M, basicity = 2.2), which was higher than that of PAC prepared by other methods. 相似文献
Electrocoagulation process was used for defluoridation of synthetic fluoride containing water. In the process Mild Steel (MS) was used as sacrificial electrode and experiments were performed with different varying parameters such as pH and current density (CD). The fluoride removal efficiency was found to be maximum at pH 6 and CD 75.44 A/m2 (2 A). At these conditions fluoride concentration reduces from initial concentration of 50 mg/dm3 to 5.2 mg/dm3. Kinetic study of electrocoagulation process revealed that the order of the reaction was in the range 1.61–1.64 with respect to fluoride concentration. It was observed that fluoride removal efficiency of the present MS electrode is comparable to the other electrodes used in electrocoagulation process available in the literature. 相似文献
A study was conducted on the treatment of landfill leachate by combining the sequencing batch biofilm reactor (SBBR) method with the electro-Fenton method. The reduction of chemical oxygen demand (COD), biological oxygen demand (BOD5), and ammonia nitrogen (NH4+-N) from the leachate by the SBBR method was investigated. For the electro-Fenton experiment, the changes in COD and total organic carbon (TOC) with the increase in H2O2 dosage and electrolysis time under optimal conditions were also analysed. The results showed that the average efficiencies of reduction of COD, BOD5, and NH4+ -N achieved using the SBBR method were 21.6 %, 54.7 %, and 56.1 %, respectively. The bio-effluent was degraded by the subsequent electro-Fenton process, which was rapid over the first 30 min then subsequently slowed. After 60 min of the electro-Fenton treatment, the efficiencies of reduction of TOC, COD, and BOD5 were 40.5 %, 71.6 %, and 61.0 %, respectively. There is a good correlation between the absorbance of leachate at 254 nm (UV254) and COD or TOC during the electro-Fenton treatment. 相似文献
Electron-beam irradiation considered on advanced oxidation process induces the decomposition of pollutants in industrial effluent. Experiments were conducted using a radiation dynamics electron beam accelerator with 1.5 MeV energy and 37 kW power. The effluent samples from an industrial complex were irradiated using the IPEN's liquid effluent irradiation pilot plant. The experiments were conducted using one sample from each of eight separate industrial units and five samples of a mixture of these units. The physical–chemical characterization of these samples is presented. The electron beam irradiation was efficient in destroying the organic compounds delivered in these effluents, mainly, chloroform, dichloroethane, methyl isobutyl ketone, toluene, xylene and phenol. The necessary dose to remove 90% of the most organic compounds from industry effluent was 20 kGy. The removal of organic compounds from this complex mixture was explained by the destruction G value (Gd) that was obtained for those compounds with different initial concentrations and was compared with literature. 相似文献