Journal of Water and Environmental Nanotechnology
Volume:3 Issue: 3, Summer 2018

The magnetic mesoporous Fe3O4 and Fe3O4/Carbon Nanocomposite (Fe3O4/C) are synthesized by a facile hydrothermal method in one- step and are used for methylene blue dye removal. Nanomaterials are characterized by field-emission scanning electron microscope (FE-SEM), transition electron microscopy (TEM), energy dispersive X-ray spectrometry (EDX), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and Vibrating sample magnetometry (VSM). The specific surface area of the samples and mean pore diameter were measured via Brunauer–Emmett–Teller (BET) surface area measurement technique. To improve the adsorption performance some important parameters affecting dye removal are optimized. Maximum capacity for methylene blue (MB) adsorption on to Fe3O4 and Fe3O4/C Nanocompositeis 169.5 and 208.33 mg. g-1, respectively, which compared to some same recent reports, has a better adsorption capacity. Thermodynamic parameters (ΔGο, ΔΗο and ΔSο) were calculated and the result showed a spontaneous, endothermic and increase in randomness for dye adsorption. The obtained data has the best fitting with Langmuir isotherm and the kinetic analysis has the best fit by pseudo-second order model.

Oil production from oil reservoirs containing oil in water (O/W) and water in oil (W/O) emulsions has always been accompanied by some problems. The increase in apparent viscosity of the oil, pore throats blockage, and consequently, the increased rate of pressure drop are among these problems. Investigating the behavior of this type of oil in the porous medium can help to understand the problem. Although metal oxide nanoparticles can increase the oil recovery and therefore improve the performance of reservoirs, they can result in the formation of W/O emulsions, due to their potential properties. In this study, the formation and stability of the emulsion were first evaluated and then the nanofluids were injected into a carbonate sand pack. Tests were conducted in the ambient condition. The amount of produced oil in the presence of three nanoparticles consist of TiO2, SiO2, and Fe3O4 has been investigated. Moreover, the effect of water injection on the system containing emulsions created by both different ions present in the seawater and iron oxide nanoparticles has been investigated. The results show that the iron oxide nanoparticles cause high-pressure oscillations by forming more stable emulsions in the porous media.

The methylene blue (MB) adsorption from aqueous solution was investigated through Fe3O4 nanoparticles loaded on Fish Scale (FS) from fishery biomass. The presence of collagen fibers, apatite crystals and nano-magnetite particles in the structure of nano-magnetic fish scale (MFS) was observed in FTIR, EMA and XRD results. From nitrogen physisorption studies, the FS and MFS specific surface areas were estimated at 0.65 and 4.86 m2/g, respectively. The negative values of ∆G0 and ∆H0 confirmed that the adsorption was a spontaneous and exothermic process, respectively. The MB adsorption onto MFS was a physisorption controlled process. The Sips equation estimated the best fit to the data compared with other isotherm equations. The Langmuir and Sips maximum adsorption capacities (Qmax) were 68.72 and 60.87 mg/g, respectively. MB removal by MFS followed the model of pseudo-second order rate kinetics. The reusability potential of the MFS was studied, and results showed an efficiency of 59.63%.

A flexible route for the electrosynthesis of visible light active CdxZn1-xO nanostructures has been proposed. Various nanostructures were prepared by anodic dissolution in 0.1M Me4NCl by using an applied potential of 15V for 30min. The prepared nanostructures were characterized by diffuse reflectance UV-Vis spectroscopy (DRS), Fourier transforms infrared spectrometry (FT-IR), X-Ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the crystalline structure, morphology, and energy band gap of the products can be finely adjusted only by varying the duty cycle of the anodeswitching. The visible light activity of the obtained nanostructures was investigated using methyl orange as a model organic pollutant. It was found that the proposed method can be used to obtain very effective CdxZn1-xO photocatalysts by fine tuning of the morphology and energy band gap. The prepared photocatalyst retained 80% of its original activity after 5 replicated uses.

In this study, a selective, fast and novel magnetic mesoporous silica sorbent Fe3O4@MCM-41-NH2, was synthesized, functionalized and has been used for the removal of Pb+2 ions from aqueous solution. The characteristics of the Fe3O4@MCM-41-NH2 sorbent was investigated by XRD, VSM, SEM, TEM, BET, and FT-IR. The response surface methodology (RSM) based on central composite design (CCD) was utilized for estimating the effects of parameters, namely contact time (min), pH, the quantity of adsorbent (g) and initial concentration of Pb+2. The quadratic model was used as the best model for guessing variables. The results of the analysis of variance for this model were obtained with a high F-value (50.28), very low P-value (<0.0001) and non-significant lack of fit (0.2251). The maximum adsorption capacity was obtained at 46.08 mg/L. Fitting equilibrium data with different isotherm models shows that Freundlich isotherm was the best-fitted model. The pseudo-second-order model was the best model for fitting experimental data.

In this work, an efficient photocatalyst based on β-cyclodextrin-glycine-modified TiO2 nanoparticles (TiO2-Gly-βCD NPs) was successfully synthesized. The photocatalytic activity of the prepared TiO2-Gly-βCD was tested on the degradation of methylene blue (MB) and methyl orange (MO) dyes. The enhanced surface properties of TiO2-Gly-βCD photocatalyst generated excellent photocatalytic performance for the photocatalytic degradation of dyes in aqueous solution. These were strongly attributed to the presence of the functional hydroxyl groups and the inner cores of the hydrophobic cavity in β-CD to form inclusion complexes with organic molecules. As compared to the pure TiO2 and TiO2 modified by Gly, the dye degradation rate under UV irradiation was considerably enhanced by TiO2/Gly/βCD as a photocatalyst. In addition, the sonocatalytic degradation of dyes was investigated, and it was found that the ultrasonic waves slightly enhanced the degradation time of dyes. The results indicated that the first-order kinetic model well describes the degradation of MB and MO dyes by TiO2-Gly-βCD. Furthermore, the chemical oxygen demand (COD) values were determined for real industrial wastewater and treated wastewater.

In the current work, the natural zeolite was modified with cobalt hexacyanoferrate and employed for adsorbent of Pb(II) ions from aqueous solution. The modification was approved by XRD and FTIR techniques. The Pb(II) adsorption capacity enhanced by 1.8 times from 60 mg/g (natural zeolite) to 100 mg/g (modified zeolite) at optimal conditions. Factors such as time, pH, temperature, adsorbent dosage and initial concentration were investigated to optimize the adsorption condition. A fast sorption was observed in the initial contact time and equilibrium was achieved in less than 120 min. The optimum pH for lead removal was between 3 and 6. The adsorption capacity was increased and reached the maximum of 90 % at 2 g/L adsorbent dosage. Also, the adsorption increased as the concentration increased up to 500 mg/L and the sorption became constant at higher concentration. It was found that the double-exponential model describes the lead sorption kinetics and the Langmuir–model describe the isotherms.

ZnO/bentonite photocatalyst was synthesized using different methods, including: precipitation, liquid-state ion exchange (LSIE) and solid-state Ion exchange (SSIE) methods. In most studies done so far, LSIE and precipitation method have been used to prepare composites. The SSIE is a new method. The purpose of this research is to produce nanocomposites with each of these methods and compare their photocatalytic activity. The physicochemical properties of the prepared photocatalysts were determined by scanning electron microscope (SEM), energy dispersive X-ray (EDX) and diffusive reflective spectroscopy (DRS) analysis. The Photocatalytic activity was evaluated by degradation of methyl orange (MO) with the prepared photocatalysts. SEM images showed that the ZnO particles were successfully distributed on the bentonite in the samples prepared by precipitation method. Nevertheless, after ion exchange-based methods, no particles were formed on the bentonite surface. This is because of very small size of ZnO particles which in the interlayer space of bentonite. The EDX and DRS analysis confirmed the formation of composites. The photodegradation of MO were 84, 85 and 87% for the composites prepared by LSIE, SSIE and precipitation methods, respectively. Ultimately, the photocatalytic composites prepared by the solid-state method are very bright due to their simple production, low price and short time due through direct heating of the reaction.