Experimental design for copper cementation process in fixed bed reactor using two-level factorial design

AbstractThis work deals with cementation of copper onto iron grid in a fixed bed reactor. The influence of several parameters is studied, namely: initial concentration of copper [Cu2+]0, temperature and flow rate. Moreover, their influence on the copper cementation reaction is investigated statistically by the experimental design in view of industrial application. The estimation and the comparison of the parameter’s effects are realized by using two-level factorial design. The analysis of these effects permits to state that the most influential factor is initial concentration of copper [Cu2+]0 with an effect of (+2.4566), the second in the order is the temperature with an effect of (+0.18959), the third is the flow rate of the electrolytic solution with an effect of (−0.4226). The significance interactions found by the design of experiments are between initial concentrations of copper ions–flow rate (x1x3) with an effect (b13=+0.6965)

Enhancement of the biodegradability of a mixture of dyes (methylene blue and basic yellow 28) using the electrochemical process on a glassy carbon electrode

International audienceThe coupling of an electrochemical process with a biological treatment for the degradation of methylene blue (MB) and basic yellow 28 (BY28) considered separately or in mixture on a glassy carbon electrode was examined in this study. It was shown that color removal efficiency and mineralization yield of MB, BY28, and their mixture increased with the working potential and decreased with the initial dye concentration. The optimal conditions were found to be E=2.4V/SCE, [MB](0)=50mg L-1, [BY28](0)=50mg L-1, pH=2, T=25 degrees C, and =600rpm, which led to 100% color removal after 120 and 240min of reaction time for BY28 and MB, respectively. Under these optimal conditions, the mineralization yield of BY28, MB, and their mixture (50mg L-1 of each dye) was close to 59, 57, and 54% within 360min of reaction time, respectively. The biological oxygen demand (BOD5)/chemical oxygen demand (COD) ratio increased substantially after 360min of pre-treatment from 0.04 to 0.27 for the dyes mixture. Microbial degradation was therefore performed for the pre-treated mixture solution and the results showed significant mineralization yield leading to an overall dissolved organic carbon decrease of 78% for the coupled process. It was therefore shown the presence of residual refractory compounds at the end of the culture which was illustrated by the decrease of the BOD5/COD ratio (0.045) obtained for the final solution. However, biodegradability was improved after a recycling of the solution in the electrochemical oxidation pre-treatment during 180min leading to a BOD5/COD ratio of 0.73

Effect of Sulfur Concentration on the Morphology of Carbon Nanofibers Produced from a Botanical Hydrocarbon

Carbon nanofibers (CNF) with diameters of 20–130 nm with different morphologies were obtained from a botanical hydrocarbon: Turpentine oil, using ferrocene as catalyst source and sulfur as a promoter by simple spray pyrolysis method at 1,000 °C. The influence of sulfur concentration on the morphology of the carbon nanofibers was investigated. SEM, TEM, Raman, TGA/DTA, and BET surface area were employed to characterize the as-prepared samples. TEM analysis confirms that as-prepared CNFs have a very sharp tip, bamboo shape, open end, hemispherical cap, pipe like morphology, and metal particle trapped inside the wide hollow core. It is observed that sulfur plays an important role to promote or inhibit the CNF growth. Addition of sulfur to the solution of ferrocene and turpentine oil mixture was found to be very effective in promoting the growth of CNF. Without addition of sulfur, carbonaceous product was very less and mainly soot was formed. At high concentration of sulfur inhibit the growth of CNFs. Hence the yield of CNFs was optimized for a given sulfur concentration

Phosphorus poisoning during wet oxidation of methane over Pd@CeO2/graphite model catalysts

10siThe influence of phosphorus and water on methane catalytic combustion was studied over Pd@CeO2 model catalysts supported on graphite, designed to be suitable for X-ray Photoelectron Spectroscopy/Synchrotron Radiation Photoelectron Spectroscopy (XPS/SRPES) analysis. In the absence of P, the catalyst was active for the methane oxidation reaction, although introduction of 15% H2O to the reaction mixture did cause reversible deactivation. In the presence of P, both thermal and chemical aging treatments resulted in partial loss of activity due to morphological transformation of the catalyst, as revealed by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) analysis. At 600 °C the combined presence of PO43− and water vapor caused a rapid, irreversible deactivation of the catalyst. XPS/SRPES analysis, combined with operando X-ray Absorption Near Edge Structure (XANES) and AFM measurements, indicated that water induces severe aggregation of CeO2 nanoparticles, exposure of CePO4 on the outer layer of the aggregates and incorporation of the catalytic-active Pd nanoparticles into the bulk. This demonstrates a temperature-activated process for P-poisoning of oxidation catalysts in which water vapor plays a crucial role.partially_openembargoed_20171009Monai, Matteo; Montini, Tiziano; Melchionna, Michele; Duchoň, Tomáš; Kúš, Peter; Tsud, Nataliya; Prince, Kevin C.; Matolin, Vladimir; Gorte, Raymond J.; Fornasiero, PaoloMonai, Matteo; Montini, Tiziano; Melchionna, Michele; Duchoň, Tomáš; Kúš, Peter; Tsud, Nataliya; Prince, Kevin C.; Matolin, Vladimir; Gorte, Raymond J.; Fornasiero, Paol

Modeling of drying thin layer of tomato slices using solar and convective driers

This paper presents a mathematical modelling of thin layer drying of tomato (Solanum lycopersicum L.). To this end, two different methods are used to dehydrate tomato slices namely the solar drying (in an indirect solar dryer), and the forced convective drying (in a convective dryer). In the solar dryer, the experiments are carried out at a constant air velocity of 1 m/s and average temperatures of 37.2, 39.9, 42.5 °C. In the convective dryer, the experiments are performed with five different temperatures (30, 40, 50, 60 and 70 °C) at a constant air velocity of 1 m/s. In order to estimate and select the appropriate drying curve equation, fifteen different thin layer mathematical drying models available in the literature are applied to the experimental data. The models are compared using the correlation coefficient (r) and the standard error (s) and are predicted by a non-linear regression analysis using the Curve Expert software. The Midilli-Kucuk model shows a better fit to the experimental drying data according to (r) and (s) for the two drying methods. The effect of the drying temperature on the parameters of this model is also determined. The experimental drying curves show only a falling drying rate period. On average, tomatoes are dried until the moisture content of 0.15 kg water/kg dry matter from 14.36 kg water/kg dry matter in the solar drying, and to the moisture content of 0.10 kg water/kg dry matter from 12.66 kg water/kg dry matter in the convective drying.

Heterogeneous Electro-Fenton Process Using a Cathode of Carbon Felt Impregnated with Iron for the Degradation and Biodegradability Enhancement of Sulfamethazine

International audienceThe objective of this study was to develop a carbon felt impregnated with iron (III) sulfate (CF-Fe) for its use both as a cathode and reusable heterogeneous catalyst source in the Fenton reaction for the elimination of sulfamethazine (SMT). The CF-Fe cathode was characterized with Scanning electron microscopy-energy dispersive spectrometric (SEM–EDS) and X-ray diffraction (XRD). The results of morphology characterization with SEM–EDS revealed that the raw CF displayed a rod-like morphology with a clean and smooth surface. After the impregnation of CF with iron (III) sulfate, the surface of CF-Fe became rough and porous while retaining the raw CF structure well. Furthermore, some solid particles were clearly observed on the FC-Fe, suggesting that the iron species were loaded onto the CF–Fe surface, which contained 57.20% w of iron. The XRD indicated that iron species were successfully embedded in the CF. The effect of the current intensity and injected compressed air flow on the production of hydrogen peroxide (H2O2) was investigated. From the obtained results, it is shown that the highest concentrations of H2O2 are produced at I = 50 mA and 0.2 L min−1 compressed air flow rate. The effect of current intensity on the degradation and mineralization rate of SMT was investigated by varying the current intensity from 20 to 100 mA. At the optimal current applied (50 mA), the total degradation of SMT and a maximum of 70.2% mineralization were achieved after 120 min electrolysis. In addition, the biodegradability of the solutions electrolyzed under several experimental conditions was performed. The results revealed that the BOD5/COD ratio increased from 0 to 0.42 after 120 min when the solutions were electrolyzed at 100 mA; while, when the electrolysis was performed at 50 mA no biodegradability was observed. Finally, the stability of the CF–Fe cathode was evaluated during six consecutive cycles. The results showed that the total degradation of SMT was achieved in less than 120 min of treatment and remained the same even after six cycles. However, a significant decrease in the mineralization rate was observed, since the mineralization rate decreased from 70 to 36% after six cycles, due to the leaching of iron at the cathode, as demonstrated by the results of the evolution of total iron in solution. In view of the results obtained, the heterogeneous electro-Fenton process using CF-Fe cathode is promising to treat the SMT containing wastewater

Removal of tetracycline hydrochloride from water based on direct anodic oxidation (Pb/PBO2 electrode) coupled to activated sludge culture

International audienceThe removal of tetracycline hydrochloride by an electrochemical oxidation on Pb/PbO2 electrode and the feasibility of coupling anodic oxidation-activated sludge culture were examined. The effect of the operating parameters showed that tetracycline hydrochloride (TC) degradation was enhanced for increasing current density and decreasing dye concentrations. The operating parameters were then optimized through a central composite design (CCD). After performing a screening of the various factors, response surface analysis led to the following optimal conditions for the abatement of the dissolved organic carbon (DOC): 26 C, 25 mA cm 2, 100 mg L 1 and 720 rpm for the temperature, the current density, the initial antibiotic concentration and the agitation speed, respectively. Under these conditions, 86.7% of the dissolved organic carbon was removed. To ensure a significant residual organic content for activated sludge culture after electrochemical pre-treatment, the biodegradability test and the biological treatment were performed on a solution electrolyzed at 40 C, 13.75 mA cm 2, 100 mg L 1 and 720 rpm, according to the total removal of tetracycline observed while 36.7% of the dissolved organic carbon (DOC) remained after electrolysis. The BOD5/COD ratio increased substantially from 0.028 initially to 0.41 after 5 h of electrochemical pre-treatment, namely slightly above the limit of biodegradability (0.4). A biological treatment was therefore performed aerobically in a mineral medium using 0.5 g L 1 of activated sludge for 30 days, leading to an overall decrease of 76% of the dissolved organic carbon (DOC) by means of the combined electrochemical pre-treatment and a biological treatment

Combination of an electrochemical pretreatment with a biological oxidation for the mineralization of nonbiodegradable organic dyes: Basic yellow 28 dye

International audienceThe aim of this article was to examine the feasibility of combining an electrochemical degradation of wastewater containing Basic Yellow 28 (BY28) dye on Pb/PbO2 electrode and a biological treatment. A central composite design (CCD) was used for the screening of the significant operating parameters and the identification of the most relevant interactions. The model equation obtained led to a classification of these parameters based on their level of significance, namely temperature followed by the initial concentration of BY28, the current density and the agitation speed. A significant interaction occurred between the temperature and the initial dye concentration. The second-order model obtained by CCD led to the following optimal conditions for dye degradation: 50 T 60 C, 8.125 i 25 mA cm22, [BY28]05134 mg L21, and x5720 rpm. Under these conditions, the obtained BY28 dye degradation yield was 96%. The (BOD5/COD) ratio increased from 0.076 initially to 0.30 after pretreatment, showing that the electrochemical pretreatment of BY28 dye generate intermediate products, which are at least partially biodegradable. Microbial degradation was therefore performed for the pretreated solution in an aerobic batch reactor for 30 days using an activated sludge culture. A decrease of the residual amount of intermediate products contained in the electrolyzed solutions was observed which can be related to a biological oxidation, leading to 93% removal of the dissolved organic carbon by the combined process

Effects of acid-basic treatments of date stones on lead (II) adsorption

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The combination of photocatalysis process (UV/TiO2(P25) and UV/ZnO) with activated sludge culture for the degradation of sulfamethazine

International audienceThe major factors affecting the removal efficiency of sulfamethazine (SMT) by photocatalysis process in the presence of TiO2 P25 or ZnO, namely the pH, the amount of catalyst and the initial SMT concentration were examined. The obtained results showed the absence of adsorption of SMT on the catalysts and the absence of degradation of SMT by direct photolysis under UV light in the absence of catalyst. The variation of the pH solution in the range 4-9 did not cause any significant degradation of SMT. The optimal amounts of each catalyst were, respectively, 0.5 and 0.25g/L for TiO2 P25 and ZnO. Increasing the initial SMT concentration impacted negatively the removal efficiency, which decreased from 31% to 13% and from 100% to 27% in the presence of TiO2 P25 and ZnO in the presence of 10mg/L and 50 of SMT after 30-min reaction time, respectively. The obtained results showed better efficiency of ZnO than TiO2 P25 regarding both removal efficiency and chemical oxygen demand (COD) abatement. However, removal efficiency and COD abatement were not complete, even after 7h of photocatalysis, about 92% and 41%, respectively. The biodegradability was examined after photocatalysis performed in the following conditions [SMT](0)=50mg/L, pH=6, T=25 degrees C, =360 rpm and 0.5g/L of TiO2 P25 or 0.25g/L of ZnO. In these conditions, the removal efficiencies were, respectively, 26% and 41% in the presence of TiO2 P25 and 55 and 92% in the presence of ZnO after 4 and 7h of pretreatment times, respectively. The BOD5/COD ratio increased substantially and, respectively, from 0 to 0.25 and from 0 to 0.16 in the presence of TiO2 P25 and ZnO after 7 h of irradiation. Even if the limit of biodegradability (0.4) was not achieved, a subsequent biological treatment was considered in the presence of TiO2 P25, leading to 58% COD abatement after a 28-day culture