Using of a New Carbon Nano Tube Version in Sheet Shape for Water and Wastewater Treatment

Removal of xylene (a toxic compound) from aqueous solution by modified multi wall carbon nano tubes (MWCNT) via silica as sheeted carbon nanotube (SCNT) was evaluated. The physicochemical properties of MWCNT such as structure and availability surface were improved due to convert tubes into sheets that cause significantly increase in xylene adsorption. The equilibrium amount (qe (mg/g)) in nano material's dose of 1g/l, xylene concentration of 10mg/l, contact time of 10min, and pH 7, for SCNT (qe 9.8 mg/g) was higher than single wall carbon nano tubes (SWCNT) (qe 9.2 mg/g) and MWCNT (qe 8.9 mg/g). It is concluded that sheeted carbon nanotube due to their large surface area improve performance of xylene adsorption. Also carbon nano tube (CNT) recycling by heating, showed better adsorption performance for recycled SCNT. A comparison study on xylene adsorption revealed that sheeted carbon nanotube has better xylene adsorption performance as compared to CNT, carbon and silica adsorbents. This suggests that the SCNT is an efficient adsorbent for xylene removal in environmental pollutions cleanup. When you are citing the document, use the following link http://essuir.sumdu.edu.ua/handle/123456789/3508

Comparison of electrochemical advanced oxidation processes for removal of ciprofloxacin from aqueous solutions

The aim of this study was to compare the efficiency of two dimensional electrochemical (2DE), electro-Fenton (EF), three dimensional electrochemical (3DE) and three dimensional electro-Fenton (3DEF) processes in removal ciprofloxacin (CIP) from aqueous solutions. The central composite design (CCD) with response surface methodology (RSM) was used to study the effect of experimental parameters on the removal efficiency of CIP by various electrochemical processes. The results showed that obtained quadratic model had a high R-squared coefficient based on the analysis of variance (ANOVA). The optimum condition for the removal of CIP by the studied processes was pH of 3, current of 0.45 A, and electrolysis time of 60 min. The results of the comparison between the processes showed that the removal efficiency of CIP after 60 min of electrolysis time is reduced as follows: 3DEF>3DE>EF>2DE. The removal efficiency enhancement was attributed to much more hydroxyl radicals generated in the three dimensional (3D) processes because single-walled carbon nanotubes (SWCNTs) could activate molecular oxygen to produce more H2O2 . These results showed that 3D systems, especially 3DEF, could be considered as an appropriate method for the treatment of persistent pollutants such as antibiotics due to good electro-catalytic activity, high efficiency, no secondary pollution

Removal of a common textile dye, navy blue (NB), from aqueous solutions by combined process of coagulation–flocculation followed by adsorption

The decolorization and removal of chemical oxygen demand (COD) of a textile dye, Navy blue CE-RN (NB), were investigated from aqueous solutions by combined process of coagulation–flocculation(C–F) and adsorption. Common coagulants (alum, lime, poly aluminum chloride (PACl), and ferric chloride) and clay montmorillonite (Mt) and nanomontmorillonite (NMt) were used in C–F and adsorption steps, respectively. The maximum COD and dye removal was observed by coagulant of PACl in the C–F process. The optimum conditions for dye removal by PACl were occurred by coagulant dose of 0.1 g/L at pH 6. In the adsorption process, the optimum contact times of 120 and 20 min were obtained for Mt and NMt, respectively. The findings indicated that the optimum conditions for the dye sorption were observed at pH 2 and the adsorbent dose 1.8 g/L. The sorption data also showed that the adsorption of NB onto the sorbents was better followed the pseudo-second order kinetic models. The dye and COD concentrations during the combined treatment process were decreased from 300 to 2–4.5 mg/L and from 732 to 2–35 mg/L, respectively. This indicates that the combined process of C–F followed by adsorption can be used as a proper alternative for the treatment of NB dye-containing wastewaters. © 2015 Balaban Desalination Publications. All rights reserved

Benzene and Toluene Removal by Carbon Nanotubes from Aqueous Solution

The removal of benzene (B) and toluene (T) from aqueous solution by multi walled, single walled, and hybrid carbon nanotubes (MWCNTs, SWCNTs, and HCNTs) was evaluated for a nanomaterial dose of 1 g/l, concentration of 10-100 mg/l, and pH 7. The equilibrium amount removed by SWCNTs (B: 9.98 mg/g and T: 9.96 mg/g) was higher than for MWCNTs and HCNTs. Toluene has a higher adsorption tendency on CNTs than benzene, which is related to the increasing water solubility and the decreasing molecular weight of the compounds. The SWCNTs performed better for B and T sorption than the MWCNTs and HCNTs. Isotherms study based on isofit program indicate that the Generalized Langmuir-Freundlich (GLF) isotherm expression provides the best fit for benzene sorption, and that Brunauer-Emmett-Teller (BET) isotherm is the best fit for toluene adsorption by SWCNT. SWCNTs are efficient B and T adsorbents and possess good potential applications to water and wastewater treatment and maintain water of high quality that could be used for cleaning up environmental pollution

Degradation of diclofenac by heterogeneous electro-Fenton process using magnetic single-walled carbon nanotubes as a catalyst

Degradation of diclofenac (DCF)from aqueous solution was investigated by the heterogeneous electro-Fenton (EF)process using magnetic single-walled carbon nanotubes (MSWCNTs)as a new catalyst. The effect of parameters including initial pH, current density, initial catalyst concentration, the initial concentration of DCF and air flow rate on the efficiency of DCF removal and electrochemical production of H 2 O 2 were studied. A removal efficiency of 97.8 for DCF and 71.12 for COD was obtained at an initial pH of 5, current density of 20 mA/cm 2 , MSWCNTs concentration of 80 mg/L, DCF concentration of 10 mg/L, air flow rate of 1 mL/min and reaction time of 120 min. Regarding the removal of DCF and COD, and production of H 2 O 2 , the heterogeneous EF process with MSWCNTs catalyst showed higher activity and efficiency than other electro-catalytic degradation systems. The stability tests of MSWCNTs after 5 time application confirmed its performance potential for long-term degradation of DCF in aqueous solutions. Intermediate products such as 2,3-dichlorobenzene and 2,4-dichlorophenol were identified by gas chromatography-mass spectrometry (GC�MS). Based on the identification of reactive species and the intermediate products, a possible mechanism of removal and degradation pathways for DCF was suggested. © 2019 Elsevier Lt

Electrochemical Degradation of Reactive Black 5 Using Three-Dimensional Electrochemical System Based on Multiwalled Carbon Nanotubes

The removal of Reactive Black 5 (RB5) dye and chemical oxygen demand (COD) was investigated using a three-dimensional (3D) electrochemical (3DE) reactor with multiwalled carbon nanotubes (MWCNTs). The experiments were performed according to a Taguchi design model, with the variables being the solution pH (2-9), current density (10-25 mA/cm2), reaction time (15-60 min), MWCNT concentration (25-200 mg/L), and RB5 concentration (25-100 mg/L). The best conditions for optimum removal of RB5 and COD were pH 3, MWCNT concentration 200 mg/L, current density 15 mA/cm2, RB5 concentration 100 mg/L, and reaction time 60 min. Among the main factors, the solution pH for removal of COD and RB5 and the current density for energy consumption had the highest impact. The 3D system generated more H2O2 and OH radicals compared with a two-dimensional (2D) system because the MWCNTs act as microelectrodes in the optimal conditions. In the 3D process, the production of high levels of reactive species led to an increase in the degradation of RB5 into aromatic compounds and various acids. © 2019 American Society of Civil Engineers

Three dimensional electro-Fenton oxidation of diclofenac and naproxen with magnetic bentonite as a novel particle electrode

Magnetic bentonite (MBt) and Ti/TiO2 nanotube/PbO2, for the first time, were investigated as particle electrodes and anode of three dimensional electro-Fenton process (3DEF) for the degradation of diclofenac (DCF) and naproxen (NPX). The characteristics of the electrodes were determined by X-ray diffraction(XRD), scanning electron microscope(SEM) and energydispersive X-ray spectroscopy(EDS) analyses and the effects of operating parameters on degradation were studied. The results showed that adsorption and electrochemical processes have lower removal efficiency than the 3DEF process at neutral pH. This efficiency was due to the greater production of hydroxyl radical (�OH) through the anode and MBt surface. The results of the scavenging experiments confirmed an increase in the amount of production of �OH. The maximum removal efficiency of DCF and NPX was obtained at pH of 6, MBt dosage of 500 mg/L, current density of 25 mA/cm2and electrolysis time of 120 min. The electrodes reusability was confirmed by consecutive reaction cycle and the Fourier-transform infrared spectroscopy (FTIR) and SEM-mapping analysis explained their stability. The results of continuous electro-oxidation reactor showed proper removal of the chemical oxygen demand(COD) from real wastewater. The degradation by-products were identified by gas chromatography mass-spectrometry (GC-MS) analysis coupled with dispersive liquid�liquid microextraction (DLLME). Based on comparative tests and products identification, the possible mechanism and pathway of drugs degradation were suggested. © 2020, © 2020 Informa UK Limited, trading as Taylor & Francis Group

Three dimensional electro-Fenton oxidation of diclofenac and naproxen with magnetic bentonite as a novel particle electrode

Magnetic bentonite (MBt) and Ti/TiO2 nanotube/PbO2, for the first time, were investigated as particle electrodes and anode of three dimensional electro-Fenton process (3DEF) for the degradation of diclofenac (DCF) and naproxen (NPX). The characteristics of the electrodes were determined by X-ray diffraction(XRD), scanning electron microscope(SEM) and energydispersive X-ray spectroscopy(EDS) analyses and the effects of operating parameters on degradation were studied. The results showed that adsorption and electrochemical processes have lower removal efficiency than the 3DEF process at neutral pH. This efficiency was due to the greater production of hydroxyl radical (�OH) through the anode and MBt surface. The results of the scavenging experiments confirmed an increase in the amount of production of �OH. The maximum removal efficiency of DCF and NPX was obtained at pH of 6, MBt dosage of 500 mg/L, current density of 25 mA/cm2and electrolysis time of 120 min. The electrodes reusability was confirmed by consecutive reaction cycle and the Fourier-transform infrared spectroscopy (FTIR) and SEM-mapping analysis explained their stability. The results of continuous electro-oxidation reactor showed proper removal of the chemical oxygen demand(COD) from real wastewater. The degradation by-products were identified by gas chromatography mass-spectrometry (GC-MS) analysis coupled with dispersive liquid�liquid microextraction (DLLME). Based on comparative tests and products identification, the possible mechanism and pathway of drugs degradation were suggested. © 2020, © 2020 Informa UK Limited, trading as Taylor & Francis Group

Adsorption of methylene blue from aqueous solutions by cellulose and nanofiber cellulose and its electrochemical regeneration

This study was conducted to evaluate the potential of the bleached bagasse, cellulose, and nanofiber cellulose to remove methylene blue (MB) from aqueous solution. The morphology of adsorbents surface and their functional groups were examined by using scanning electron microscope and Fourier transform infrared spectroscopy techniques, respectively. In a batch mode study at 25°C temperature, the effects of initial dye concentration, contact time, adsorbent dose, and solution pH on adsorption performance were investigated. The results showed that the percent of MB removal increases by increasing pH and also by increasing sorbent dosage and decreasing initial dye concentration. The adsorption kinetics and equilibrium data were in good agreement with the pseudo-second-order kinetic model and Freundlich adsorption isotherm, respectively. The removal of MB was better and more effective with cellulose and cellulose nanofiber as compared with the bleached bagasse. The regeneration of cellulose and nanofiber cellulose loaded with MB was investigated using electrochemical method under different operating conditions. The results showed that the electrochemical process efficiency is more than 60 for regeneration adsorbents. © 2018 Desalination Publications. All rights reserved

Biohydrogen production under hyper salinity stress by an anaerobic sequencing batch reactor with mixed culture

Background: This study investigated the effect of organic loading rate (OLR) and NaCl concentration on biohydrogen production by preheated anaerobic sludge in a lab scale anaerobic sequencing batch reactor (ASBR) fed with glucose during long time operation. Methods: During ASBR operation, the OLR was increased in steps from 0.5 to 5 g glucose/L.d and NaCl addition started at an OLR of 5 g glucose/L.d, to obtain NaCl concentrations in the reactor in the range of 0.5-30 g/L. Results: With an increasing OLR from 0.5 to 5 g glucose/L.d, the biohydrogen yield increased and reached 0.8 ± 0.4 mol H2/mol glucose at an OLR of 5 g glucose/L.d. A NaCl concentration of 0.5 g/L resulted in a higher yield of biohydrogen (1.1 ± 0.2 mol H2/mol glucose). Concentrations above 0.5 g/L NaCl led to decreasing biohydrogen yield and the lowest yield (0.3 ± 0.1 mol H2/mol glucose) was obtained at 30 g/L of NaCl. The mass balance errors for C, H, and O in all constructed stoichiometric reactions were below 5%. Conclusions: The modified Monod model indicated that r (H2)max and Ccrit values were 23.3 mL H2/g VSS/h and 119.9 g/L, respectively. Additionally, ASBR operation at high concentrations of NaCl shifted the metabolic pathway from acidogenic toward solventogenic.Sanitary Engineerin