Journal of Water and Environmental Nanotechnology
Volume:2 Issue: 3, Summer 2017

Although several studies concerning the preparation of nitrogen doped titanium dioxide visible-light active photocatalyst have already been reported, the effects of dopant concentration and calcination temperature have been rarely investigated. This paper focuses on the preparation of nitrogen doped titanium dioxide (N-doped TiO2) under different calcination temperature and nitrogen dopant concentration synthesizes by sol-gel method. The physicochemical characteristics of the prepared samples were examined using X-ray photoelectron spectroscopy (XPS), X-ray diffractometer (XRD), Brunauer Emmett Teller (BET) analyzer, and UV-Vis spectrometer. Methylene blue was used in this study as a test chemical. The results demonstrated that the sample prepared under calcination temperature of 600 oC show 8.33 and 5.57 % of rutile TiO2 phase depends on the dopant concentration. Furthermore, the sample prepared at a lower calcination temperature of 400 oC and nitrogen to titanium (N/Ti) molar ratio of 2 and 6 exhibited larger specific surface area of 80.18 and 77.07 m2g-1, respectively. The photoactivity of the catalyst was also investigated on methylene blue decolorization using the different N-doped TiO2 sample. The experiments demonstrated that the sample prepared at higher N/Ti molar ratio (6) and lower calcination temperature (400 oC) demonstrates about 80 % efficiency under visible light. It was concluded that the higher photoactivity of the N-doped sample prepared at higher dopant concentration and lower calcination temperature is due to synergistic effects of higher surface area, smaller crystal size and higher nitrogen content in the crystal lattice of TiO2.

The fabrication of functionalized membranes with hydrophobic/oleophilic surfaces for the elimination of n-hexane from water using para-aminobenzoate alumoxane, boehmite-epoxide and a novel nanoparticle, i.e., Stearate Alumoxane by a simple coating technique, is reported here. FTIR was used to characterize nanoparticles. SEM and contact angle measurement analyses were used to identify the nanocomposite membranes. The concentrations of oil in permeate and retentate were measured by UV/vis spectrophotometer. The morphology of Stearate alumoxane nanoparticles was investigated by means of SEM images. The composed film of nanoparticles on the Kevlar fabric was hydrophobic with water contact angle of ~ 145° and oleophilic with oil contact angle of ~ 0º. In addition, the membranes retained stable hydrophobicity and high separation efficiency even after employing for 6 times. Applying these properties, a setup was considered using the functionalized Kevlar fabric to separate oil through down to a collector and leave water drops. Our batch filtration system was exclusively gravity-driven. The achieved separation system can separate the oily water mixture (with the concentration of 20 % (v/v) n-hexane in water), effectively with a separation efficiency of 84%.

In isolated and arid areas, especially in the almost Maghreb regions, the abundant solar radiation intensity along the year and the available brackish water resources are the two favorable conditions for using solar desalination technology to produce fresh water. The present study is based on the use of three groups of correlation, for evaluating mass transfer. Theoretical results are compared with those obtained experimentally for a Simple Solar Distiller (SSD) and a Simple Solar Distiller Hybrid with a Heat Pump (SSDHP) stills. Experimental results and those calculated by Lewis number correlation show good agreements. Results obtained by Dunkle, Kumar and Tiwari correlations are not satisfactory with the experimental ones. Theoretical results, as well as statistical analysis, are presented. The model with heat pump ( for two configurations (111) and (001) give more output compared with the model without heat pump ((000) and (110)). This results where agree for the use of the statistic results, the error it less with Lewis number as compared with the different correlation.

The presence of Arsenic in drinking water is the greatest threat to health effects especially in water. The purpose of this study is application of green palladium nanoparticles for removal of trivalent Arsenic from aqueous solutions and also the impact of some factors such as retention time, pH, concentration of palladium nanoparticles and Arsenic concentrations was studied. The values for Arsenic removal from aqueous solutions were measured by furnace atomic adsorption spectrometry (Conter AA700). In the study, Langmuir and Freundlich isotherm models and pseudo-second order kinetic model were studied. The results of  optimization is shown that 0.5 g of nanoparticles can removed %99.8 of Arsenic with initial concentration of  0.5 g/l, in 5 minutes at pH=4. Langmuir model, Freundlich model (R2=0.94) and pseudo-second order kinetic model (R2=0.99) shown high correlation for removing of Arsenic from aqueous solutions. It was found, palladium nanoparticles can be used as an efficient method to remove Arsenic from aqueous solutions in a short time.

Cobalt is one of the most hazardous heavy metals present in the environment. Magnetic based nanoadsorbents were used for removal of Co(II) ions in this work. The characteristics results of FT-IR, XRD, TGA, and FE-SEM show that applied coatings were modified magnetite nanoparticles efficiently. The results of TEM indicate that magnetic nanoadsorbents were produced on the nanoscale with average particle sizes of 60±10 nm. Batch experiments were carried out to determine the removal efficiency of the nanoadsorbents. pH, temperature, contact time, adsorbent dose, shaking rate and the initial concentration of analyte were the studied parameters. At optimized conditions of operation parameters, the maximum removal percentage of 92% was obtained by using magnetite-citric acid as an adsorbent. Equilibrium data for Co(II) ions adsorption onto magnetite-citric acid were fitted well by Langmuir isotherm model and the maximum adsorption capacity for Co(II)ions was obtained 43.292 mg/g at 313 K. Also, thermodynamic parameters reveal the spontaneity, feasibility and endothermic nature of the Co(II) ions adsorption process. In addition, the cobalt ions can be desorbed from magnetite-citric acid nanoadsorbent by using nitric acid solution with 95% desorption efficiency and the magnetite-citric acid nanoadsorbent exhibits good recyclability.

This research reported a study on COD removal from petrochemical wastewater (ml/l) by the electroFenton process via the effects of different parameters such as reaction time, current density, pH, H2O2/ Fe2+ molar ratio, and volume fraction of H2O2. For this purpose, first, the Nanopores on the aluminum  electrode surface were prepared as the AAO films were fabricated using the two-step anodization of 6063 aluminum alloy sheets at ambient temperature in sulfuric acid and phosphoric acid electrolyte solutions respectively.The nanostructures created on electrode confirmed by Scanning Electron Microscopy (SEM). Then, Efficiency of electrochemical oxidation process was tested by COD determination via electrolyte cell contain waste water, Fe2+, H2O2 and AAO electrode based on experimental design. The optimum COD removal (65.03%) was obtained at pH of 2.96, the reaction time of 89.51 min, the current density of 69.57 mA, the H2O2/Fe2+ molar ratio of 3.42 and volume fraction of H2O2 to petrochemical wastewater of 1.93 (ml/l).

Power plants are of great influential industries to the environment which could be studied in many ways. Since the optimum equipment would consume less fuel, the issue is mainly interested to those who are concerned about the environmental effects. Amongst various methods, utilizing twisted tapes inserts which are of passive type is interested in this effort. Although numerous types of tapes are widely utilized, modifying the tape configuration according to the flow specification is still interested. So here the center-cleared and perforated tapes are considered to be compared against the typical type. The 3D numerical simulation of finite volume method was applied to cover the flow field of the problem. The RNG k-ε turbulence model was responsible for the turbulent behavior of the flow and its circular trend. In order to develop the performance of the optimum tape performance, AL2O3 nanoparticles of different volume concentrations were added to the base fluid. The results showed that the Nu number was enhanced about 22% by using merely the center-cleared 14cm, while the friction factor was increased about 13%. To develop these amounts for the optimum configuration, adding nanoparticles of 0.1% concentration put and increment of 26% for heat transfer.

Due to exhibiting an excellent chemical resistance against basic environments at high temperature, good thermal shock resistance, thermodynamic stability in the presence of carbon, and a suitable abrasion resistance, MgO-CaO refractories are widely used in argon-oxygen decarburization furnaces in the metallurgy industry and cement rotary kilns. Furthermore, MgO-CaO refractories are beneficial to removing inclusions from molten steels; thus, they have been considered to be one of the effective refractory types for processing clean steel products. Also, MgO-CaO materials have become one of the attractive steelmaking refractories because of their low cost and high ore reserves.  However, in spite of these primary advantages, the application of MgO-CaO refractories has not been popular due to its tendency to hydration when exposed to the atmosphere.  In world most of MgO-CaO bricks producers used of organic components such as tar, pitch, and peck for produce MgO-CaO refractories. But during the application of these bricks in steel and cement and industrials, they released CO and CO2 gases to air and pollute the atmosphere. For this reason, recently some researcher investigate the effect of additive nanoparticles on MgO-CaO refractories performance. They reported the used of Nano-additive have acceptable results and additive nanoparticles can replace by aforementioned environment contaminating organic compounds. In this study, we reviewed all effort that done for improving the hydration resistance of MgO-CaO refractories by application of Nano-additives with an emphasis on the beneficial the use of additives nanoparticle for reduction of environmental pollution by various industries which used of MgO-CaO refractory bricks.