Richard Feynman was the first scientist to suggest that devices and materials could someday be fabricated to atomic specifications. Later the term nanotechnology was coined. Today nanotechnology is reshaping technology. Nanotechnology is not only a part of future, but is all of it. Mankind history has always experienced waves of growth and development which affect societies, chances developed by mankind and employed to enhance the life quality and create wealth. Nanotechnology is one of these waves emerged to make a superior future. Nanotechnology is a group of emerging technologies in which the structure of matter is controlled at the nanometer scale, the scale of small numbers of atoms, to produce novel materials and devices that have useful and unique properties. Some of these technologies impose only limited control of structure at the nanometer scale, but they are already in use, producing useful products. They are also being further developed to produce even more sophisticated products in which the structure of matter is more precisely controlled. The nanotechnology community thus focuses on applying these developing technologies to solving important world problems. Although more than 70% of the earth surface is water-covered, about 97% of the world water (by volume) is too salty for drinking, irrigation or industrial use. Forecasts to 2030 indicate an increase in global water uptake at about 40% of the current accessible and reliable supplying sources, meaning an intensification of water consumption. In addition, one of the most important issue for living things is environment. Its pollution is mostly a direct result of human activities on the earth. Air, water and soil pollutions are big problems which threatens the life on the earth. To meet environmental challenges of the future in a sustainable way, for instance, wastewater must be acknowledged as a renewable resource for water, energy, nutrients and other materials. As the water sector looks to face the new challenges with innovative solutions that protect the environment, public health, and global sustainability, minimizing use of resources and maximizing the recovery of resources from wastewater is destined to become the focal point. Stringent permits in developing countries and resource constraints (especially electric power and chemicals) in developing countries demand energy-neutral wastewater treatment and resource recovery where practicable. There are already many innovative approaches and technologies that are adapted for the urban environment, which often requires intensified treatment. While these forms of treatment are becoming important everywhere, they are critical for resource scarce urban centers in the world. From these points of views, Nanotechnology can play an important role one way or another. In the other words, nanotechnology can be devoted to water and environmental technologies, nanosafety, monitoring studies and management as well. However, the mutational basis of environmental effects involving with the nanotechnology are important too. Nanoscale science and technology relevant to water and environment, risk assessment activities and regulatory policies on issues of environmental and human health and nano-focused water and environmental research as well as environmental mutation area, are the parts that need to be taken to account. We are very pleased to announce the first issue of the Journal of Water and Environmental Nanotechnology. The journal is intended to provide state-of-the-art expositions of latest advances by theoretical, numerical and experimental studies across the spectrum of the field, from scientific enquiries to practical applications. I would like to express my sincere appreciation to the editorial boards, scientific advisors, both the authors and the reviewers, for their kind support and seek the continuous promotion for making the Journal one of the most successful and pioneer academic media in this vital field. Prof. Dr. Mohsen Jahanshahi Editor-in-Chief Journal of Water & Environmental Nanotechnology

Mercury is one of the most toxic metals present in the environment. Adsorption has been proposed among the technologies for mercury adsorbent. The kinetics of adsorption depends on the adsorbent concentration, and the physical and chemical characteristics of adsorbent. In this study we were used a novel adsorbent, magnetite-polyrhodanine core- shell nanoparticles, for removing Hg(II) from aqueous solution. The effect of pH, initial Hg(II) concentration, initial adsorbent concentration and contact time on the efficiency of Hg(II) removal were investigated systematically by batch experiments. The maximum adsorption capacity was obtained 29.14 mg g-1 at PH=6.5 and 25°C with 10 g L-1 nano adsorbent. The kinetic data of adsorption of Hg(II) ion on the synthesized adsorbent were best described by a pseudo- second- order equation, indicating their chemical adsorption. The Freundlich, Langmuir and Temkin isotherms were used to modeling of mercury adsorption on Hg(II) in aqueous medium which modeled best by the Freundlich isotherm is whole concentration rage.

For the first time, uniform molecularly imprinted polymer (MIP) nanoparticles were prepared using dicamba as a template. The MIP nanoparticles were successfully synthesized by precipitation polymerization using methacrylic acid (MAA) as functional monomer, trimethylolpropane trimethacrylate (TRIM) as cross-linker and acetonitrile as a porogen. The produced polymers were characterized by differential scanning calorimetry (DSC) and their morphology was precisely examined by scanning electron microscopy (SEM). The MIP nanospheres were obtained with the average diameter of 234 nm. Batch-wise guest binding experiments were carried out to determine the removal efficiency of the produced MIP nanoparticles towards the template molecule in aqueous solutions. The MIP showed outstanding affinity toward dicamba in aqueous solution with maximum removal efficiency of 87.5% at 300 mg.L-1 of dicamba solution. The MIP exhibited higher adsorption efficiency compared with the corresponding non-imprinted polymer (NIP) as well as outstanding selectivity towards dicamba relative to the template analog in an aqueous solution. Moreover, effects of pH on removal efficiency and selectivity of MIP were evaluated in detail.

Multiwalled carbon nanotubes (MWCNT) were found to be an effective separation media for purifying CO2 from O2. Significant uptakes of CO2 and O2 were measured at 288 K, 298K and 308 K over the pressure range of 1 to 40 bar using a volumetric method in dual sorption vessels. The same shape of isotherms introduced a common mechanism of adsorption but the amount of CO2 adsorbed on MWCNT is 2 times higher than O2 adsorption. The mass uptake of CO2 and O2 by MWCNT was found to increase with increasing pressure and decreasing temperature. The experimental data were well fitted by the Langmuir and Freundlich model isotherms considering the values of regression correlation coefficients. Following a simple acidic treatment procedure, CO2 and O2 adsorption were increased over the range of pressure. The adsorbents were characterized by N2 adsorption isotherm at 77 K, Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and thermogravimetric analysis (TGA). The effect of temperature and pressure on selectivity obtained from IAST demonstrated that maximum selectivity over the pressure and temperature ranges p = 0.5-5 bar and T = 298–308 K was achieved at 308 K and 5 bar.

In this study, considering the importance of protecting the environment and preventing the pollution caused by industrial plants, a nanocomposite each component thereof is capable of removing the desired combination to solve this problem has been produced. To achieve this goal, ZnO/SnO2nanocomposite was synthesized using the co-precipitation method. The characterization of this nanocomposite was conducted by DLS, XRD, FTIR, and SEM. The nanocomposite size was about 15nm. Several parameters such as the initial concentration of the wastewater, as well as the amount of catalyst and time were investigated. The reduction of the particle size due to an increase in the surface area of? the nanocomposite increased the amount of decolorization. For all the performed experiments, the dye removal rate was 100% and the difference was to do with the time of the complete removal of methylene blue. A decrease in the concentration of methylene blue in the range of the tested concentrations reduced the decolorization, and by increasing the amount of nanocomposite in the range of the tested values, a decline in decolorization was observed.

The efficient application of the photocatalytic activity and superficial adsorption on removing heavy metals from water, two types of sorbents, Nd-TiO2/bentonite and Ce-TiO2/bentonite nanocomposites, were synthesized by sol-gel method. The crystalline nanocomposites were obtained after heat treatment at 500 °C for 3 hours. The results of scanning electron microscopy (SEM) indicates that Nd-TiO2/bentonite and Ce-TiO2/bentonite were produced on a nanoscale. The phase change of both nanocomposite from amorphous to anatase has been investigated by X- ray diffraction. Removal of lead (II) and cadmium (II) were studied through adsorption on these nanocomposites by letting them float in the bulk of sample for a definite time in presence and absence of light. The effective parameters in removal process were studied and optimized. The optimum pH, removal time and sorbent dosage in the absence and presence of light for Pb2+ ion were 7, 0.3 g, 15 min and for Cd2+ ion were 7, 0.4 g, 20 min, respectively. Subsequently, the effect of interfering ions in removal process was investigated at optimum conditions and no evidence of interference was observed. The study showed that reproducibility of method (n=9) is good and suitable. The results further indicated that the removal efficiency of Pb2+ ion with Nd-TiO2/bentonite in the presence of light was more than that in the absence of light. Finally, the equilibrium adsorption data fitted Freundlich and Langmuir adsorption models.

Zeolite membranes have uniform and nano-sized pores, and they separate molecules based on differences in the molecules size and diffusion properties. Different routes used to prepare zeolite composite membranes include growing zeolite layers from gels on porous supports. Our approach to membrane synthesis was based on hydrothermally converting films of layered aluminosilicates into zeolite films. In this research, synthesis of nano NaA zeolite membrane from kaolin was investigated. In the first step, kaolin has been calcined at 700 °C to the metakaolinite phase. As a second step, the zeolitisation experiments have been carried out under hydrothermal conditions. The metakaolinite obtained has been reacted with NaOH solutions in autoclaves at 100°C. X-ray diffraction (XRD) patterns of the membranes exhibited peaks corresponding to the support and the zeolite. The morphology of the support and membrane subjected to crystallization was characterized by Scanning electron microscopy (SEM). Separation performance of the NaA membranes was evaluated using pervaporation of water–Ethanol mixtures. The membranes showed high water selectivity in the water–Ethanol mixtures.

First-principles calculations within density functional theory (DFT) have been performed to investigate the interactions of NO2 molecules with TiO2/Gold nanocomposites in order to completely exploit the adsorption properties of these nanostructures. Given the need to further comprehend the behavior of the NO2 molecules positioned between the TiO2 nanoparticle and Au monolayer, we have geometrically optimized the complex systems consisting of the NO2 molecule oriented at appropriate positions between the nanoparticle and Au monolayer. The structural properties such as bond lengths, bond angles, adsorption energies and Mulliken population analysis and the electronic properties including the density of states and molecular orbitals have been also analyzed in detail. The results indicate that the interaction between NO2 and undoped TiO2-N/Gold nanocomposites is stronger than that between gas molecules and N-doped TiO2/Gold nanocomposites, which reveals that the pristine nanocomposite can react with NO2 molecule more efficiently. Therefore, the obtained results also suggest a theoretical basis for the potential applications of TiO2/Gold nanocomposites in gas sensing, which could help in the developing of novel TiO2 based advanced sensor devices.

The emerging infectious diseases and the development of drug resistance in the pathogenic microorganism is a matter of serious concern. Despite the increased knowledge of microbial pathogenesis and application of modern therapeutics, the morbidity and mortality associated with the microbial infections still remain high. Therefore, there is a pressing demand to discover novel strategies and identify new antimicrobial agents to develop the next generation of drugs or agents to control microbial infections. The use of nanoparticles is gaining impetus in the present century as they possess defined chemical, optical and mechanical properties. In the present study green synthesis of silver nanoparticles by Escherichia coli has been done. Various parameters such as mixing ratio of culture supernatant and silver nitrate, media, temperature and pH for production of silver nanoparticles were optimized. The nanoparticles synthesized were characterized using SEM, FTIR, and XRD. The antibacterial activity of silver nanoparticles synthesized using both pellet and supernatant against human pathogens Salmonella typhi, Vibrio cholerae, Bacillus subtilis and Klebsiella pneumoniae was analyzed and MIC was calculated as 20µg and 50µg respectively.

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 are shown that 0.5 g of nanoparticles can be removed %99.8 of Arsenic with the 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.

Membrane ultrafiltration (UF) is widely used in dairy industries like milk concentration and dehydration processes. The limiting factor of UF systems is fouling which is defined as the precipitation of solutes in the form of a cake layer on the surface of the membrane. In this study, the combined cake filtration-complete blocking model was compared to cake filtration mechanism for flux data through ultrafiltration of skim milk at constant flow rate. The resistance data also was modeled using cake filtration model and standard blocking model. The effect of different trans-membrane pressures and temperatures on flux decline was then investigated. Based on the results obtained here, the combined complete blocking-cake formation model was in excellent agreement with experimental data. The cake filtration model also provided good data fits and can be applied to solutions whose solutes tend to accumulate on the surface of the membrane in the form of a cake layer. With increasing pressure, the differences between the model and experimental data increased.