Removal of benzotriazole by Photo-Fenton like process using nano zero-valent iron: Response surface methodology with a Box-Behnken design

In this paper, the removal of benzotriazole (BTA) was investigated by a Photo-Fenton process using nano zero valent iron (NZVI) and optimization by response surface methodology based on Box-Behnken method. Effect of operating parameters affecting removal efficiency such as H2O2, NZVI, and BTA concentrations as well as pH was studied. All the experiments were performed in the presence of ultraviolet radiation. Predicted levels and BTA removal were found to be in good agreement with the experimental levels (R2 = 0. 9500). The optimal parameters were determined at 60 min reaction time, 15 mg L-1 BTA, 0.10 g L-1 NZVI, and 1.5 mmol L-1 H2O2 for Photo-Fenton-like reaction. NZVI was characterized using X-ray diffraction (XRD), transmission electron microscope (TEM) images, and scanning electron microscope (SEM) analysis

Heterogeneous oxidation of sulfacetamide in aquatic environment using ultrasonic and nano-fenton: Kinetics intermediates and bioassay test

In present study, degradation of sulfacetamide from a synthetic wastewater by sonofenton process using zero valent iron nanoparticles was investigated. The synthesized iron nanoparticles were characterized using transmission electron microscopy (TEM), UV-visible and X-ray diffraction pattern (XRD). The effect of various parameters, such as pH, nZVI dose, H2 O2 concentration and contact time was studied with batch experiments. The removal efficiency of sulfacetamide by US/nZVI/H2 Of process was about 91 for reaction time of 60 min, but less than 27 of chemical oxygen demand (COD) was removed. Kinetics studies showed that the degradation of sulfacetamide fitted well to the pseudo-second-order model. Using the LC/MS device, five intermediate from degradation of sulfacetamide were detected. The toxicity test, using micro toxicity study also showed that the effluent from the sono-Fenton reactor has a lower toxicity than sulfacetamide antibacterial. © 2019 Desalination Publications. All rights reserved

Inactivation of Fecal coliforms during solar and photocatalytic disinfection by zinc oxide (ZnO) nanoparticles in compound parabolic concentrators (CPCs)

Water samples of 0, 50, and 100 nephelometric turbidity units (NTU) spiked with fecal coliforms (107 CFU/ml) were exposed to natural sunshine in 1l quartz glass tubes fitted with rectors' compound parabolic concentrators CPCS at two forms CPC1 (whit nanoparticle zinc oxide) and CPC2(without nanoparticle zinc oxide). The samples were characterized using the X-ray powder diffraction (XRD), scanning electron microscopy (SEM), and transmission electron microscope (TEM). On clear days, the complete inactivation times (more than 7-log unit reduction in bacterial population) in the systems with CPC1, and CPC2 were 15, and 30 min, respectively. The maximum temperatures obtained in the water samples were 80°C for CPC1, and 82°C for CPC2. The use of CPC1 with hydroxyl radicals (OH·) production significantly improved the efficiency of the old CPCS technique, since these systems (CPC1-2) shortened the exposure times to solar radiation and also minimized the negative effects of turbidity and also regrowth was zero in the disinfected samples. Due to two simultaneous effects of high temperatures and UV, regrowth in most ways of solar disinfection was not seen in these examples. Overall, this technology has been proved to be a good enhancement method to inactivate microorganisms under real conditions and represents a good alternative technique to drinking water treatment. © 2019, Islamic Azad University

Identification of mono-and few- layer graphene: Raman study

International audienceIn this theoretical work, the Raman spectra were analyzed by considering the origin of the G peak, its shape, position and relative intensity as a function of the number of graphene layers. By using the spectral moment's method, the Raman spectra of mono, bi and few-layers of graphene are calculated and a good agreement was found with group theory concerning the number of the Raman-active modes and the Raman measurements. Our results provide a Raman analysis to evaluate the number of layers in multilayer graphene

The effects of dynamic loading on hysteretic behavior of frictional dampers

During an earthquake excitation, a frictional damper may experience many cycles of dynamic loading. The effects of wear and heat induced by the cyclic loading result in the possible decay of the slippage load which subsequently reduce the energy absorption of the damper. In this paper, the effect of dynamic loading on hysteretic behavior of a special kind of frictional damper, namely, cylindrical frictional damper (CFD), is investigated by experimental means as well as numerical models which also account for coupled thermal-structural interaction. The damper is deemed to be more susceptible to thermal deformations due to the shrink-fit mechanism by which the device is assembled. The numerical models are validated experimentally and may be utilized for simulation of dynamic cyclic loading on frictional dampers. The results demonstrate that the slippage load is reduced gradually when subjected to consecutive cycles. This drift is attributed to thermal deformation. The verified numerical models are used to improve the geometry of the CFD. With the geometrical improvements implemented, the subsequent numerical studies confirmed that almost no degradation of the slippage load occurred. Furthermore, a dimensionless parameter is introduced by the authors which shows the effect of wear on the response of CFDs. © 2014 Hamid Rahmani Samani et al

Degradation of sulfamethoxazole antibacterial by sono-fenton process using nano-zero valent iron: Influence factors, kinetic and toxicity bioassay

This study investigated the efficiency of sono-nano Fenton process in the degradation of sulfamethoxazole (SMX) antibacterial in aqueous solution. The effect of ultrasonic frequency, initial pH, the dose of nZVI, SMX concentration and hydrogen peroxide concentration are investigated. The results show that the oxidation power of Fenton system increases by ultrasonic irradiation. The optimum degradation efficiency of SMX was achieved in the condition of 1 mM H 2 O 2 , 80 kHz frequency, 1 g/L nZVI, and pH: 3 after 60 min contact with US/Fenton (about 95). Also, the degradation kinetics and toxicity test for effluent of US/nZVI/H 2 O 2 system in optimal condition were studied. It was shown that degradation of SMX could be described by a first-order kinetic model and the toxicity of treated SMX solution decreases with treatment by sono Fenton system. This study shows that US/Fenton can be used as an effective method for the treatment of polluted water and wastewater with SMX. © 2019 Desalination Publications. All rights reserved