The aim of this study is to investigate the performance of zinc oxide nano-cages (Zn12O12-NC) to detect and reduce nitrate (NO3-) ions from aqueous media and convert them to oxygen and nitrogen gases by the density functional theory (DFT) method on a B3LYP level with basis set of 6-31+G*. Due to the structure of the nano-cage (Zn12O12-NC), there are some location positions with different potential on it. The results showed that the first N atom of nitrate ion strongly prefers to be adsorbed on O atoms and O of nitrate ion is adsorbed on Zn atoms of the 4-membered ring (4-MR). The electronic, structure and thermodynamic properties of these conversions are calculated and investigated. The energy gap (Eg) of the Zn12O12-NC is dramatically reduced from 3.88 to 1.22 eV upon the adsorption of NO3- ion, suggesting that it is transformed to n-type semiconductor ascribed to the large charge transfer from the ion to the nano-cage and ions convert into oxygen and nitrogen on it. The data show that Zn12O12 nano-cage can be used to identify and reduce of nitrate ions from the environment and may be helpful in several fields of study such as sensors, catalysts, and field emission investigations.

Many studies have been done to reduce the membrane fouling and to increase the quality of the effluent from membrane bioreactor (MBR). One of the most important researches in this filed is the use of adsorbents and nanoparticles in the biological system. In this study, the effects of Fe3O4 nanoparticles were investigated using COD, extracellular polymeric substances (EPS), soluble microbial products (SMP), flux, particle size distribution (PSD) and FTIR analysis. The COD test showed that the removal rate was 86.92% in MBR without Fe3O4 (R1) and 98.17% in MBR with Fe3O4 (R2). The amount of EPS and SMP in the reactor containing nanoparticles is lower than that of a non-nanoparticle reactor. Flux rate is higher in R2, so it can be said that the presence of nanoparticles has a positive effect of reducing the membrane fouling. Also, FTIR analysis showed that the amount of protein in the biologic system R2, which is the major membrane contaminant, is greater than R1.

In the present research work, the mixed matrix membranes (MMMs) containing various amount of polyethersulfone (PES) and functionalized multi-walled carbon nanotubes (fMWCNTs) were fabricated and used to investigate the removal of cobalt ions from wastewater by nanofiltration process. Pristine MWCNTs and fMWCNTs were characterized by Fourier transformed infrared spectroscopy and thermogravimetric analysis. FESEM analysis revealed that the mixed matrix membranes have less surface defects and better membrane performance compared with neat polymeric in the removal of cobalt ions. Permeation test results showed that the MMM containing 22 wt. % PES and 0.6 wt. % fMWCNTs (with outer diameter of 10-20 nm) has the optimum performance from the permeability and cobalt removal point of view. In continuation, the effect of pressure, feed flow rate, cobalt concentration, permeation test time and feed solution pH on the removal of cobalt by selected the MMM was investigated. The obtained results indicated that only pressure has considerable effect on permeation flux. However, all parameters showed different influence on rejection percent of cobalt ions.

The corrosion inhibition effect of Areca root extract on the mild steel (MS) surface in the 3 M HCl solution was examined by gasometric, colorimetric, Tafel plot, impedance and atomic absorption spectroscopy techniques. Gasometric studies show that, the extract behaves as green corrosion inhibitor in the 3 M HCl system on the MS surface. The protection rate enhances with a rise in the plant extract concentration. Colorimetry studies show that, minimum weight loss observed at 0.4 g/L of plant extract. The minimum weight loss of MS in the 3 M HCl solution is an indication of protection property of Areca root extract. Atomic absorption spectroscopy technique shows that, increase in the amount of Areca root extract increases the protection inhibition property. Mixed corrosion inhibition property of Areca root extract was confirmed from the potentiodynamic polarization technique. Trend of charge transfer resistance values with different amounts of plant extract also supports the corrosion inhibition property of Areca root extract. SEM studies fully support the gasometric, colorimetric, Tafel plot, impedance and atomic absorption spectroscopy techniques.

In the present study, nano zeolite A (LTA) was synthesized by the alkaline fusion method without adding an organic template. Effect of temperature and aging time were studied on the crystallinity and morphology of the final product. The synthesized LTA was characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), powder X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA), differential scanning calorimetry (DSC) and N2 adsorption/desorption technique. The prepared nano LTA zeolite was applied to the water softening process. The main effects and interaction of factors such as pH, the amount of LTA, initial total hardness, temperature and contact time were investigated by response surface methodology (RSM). The obtained optimum values of factors were applied to hard water to remove Ca2+ and Mg2+ ions. Pseudo-first and second-order models were applied to kinetic and rate data. It was found that the adsorption rate follows the pseudo-second-order kinetic model.

Contaminants of emerging concern or simply emerging contaminants have been considered as a critical environmental issue in recent decades. These compounds have not routinely controlled and monitored; therefore they have posed risk to health of human and environment. Drugs are considered as one of the most important emerging pollutants. They introduce to environment form different sources such urine, human excretion, livestock, poultry, pharmaceutical, and hospitals. Although they are in trace levels, they are not biodegradable. They cannot be removed by conventional treatment processes. .. Advanced oxidation processes (AOPs) have been designed to address the deficiency of conventional methods in removal of emerging pollutants. Production of highly reactive hydroxyl radicals is the base of AOPs. These very reactive radicals effectively oxidize emerging pollutants such as drugs. Among different approach of AOPs, photocatalytic degradation has been successfully applied to mitigate the side effects of emerging contaminants. The ability of photocatalytic process in removal of Clindamycin hydrochloride (CLM) from aqueous solutions in the presence of UV/TiO2 was studied. The effects of various parameters such as adsorption, photolysis, pH, catalyst dosage, initial concentration of antibiotic, and radiation time were investigated in a batch photoreactor. Results showed that photolysis and adsorption had a negligible contribution to the clindamycin removal. The maximum clindamycin removal rate was obtained under optimal conditions, such as pH of 5, 0.5 g/l of TiO2, initial clindamycin concentration of 2 /L. This optimum condition was achieved during 90 minutes.. The CLM photocatalytic degradation kinetics showed that CLM degradation follows the pseudo-first-order kinetics.

Density functional theory calculations were carried out to investigate the adsorption behaviors and electronic structures of SO2 and O3 molecules on the pristine boron nitride nanotubes. The structural and electronic properties of the studied systems were investigated in view of the adsorption energies, band structures and molecular orbitals. Various adsorption positions of gas molecules on the boron nitride nanotubes were examined in detail. The band structure calculations indicate that the pristine BN nanotube works as a wide band gap semiconductor, and can be applied as an efficient candidate for SO2 and O3 sensing purposes. NBO analysis reveals that SO2 acts as a charge donor, whereas O3 molecule behaves as a charge acceptor from the BN nanotube. Molecular orbital calculations indicate that the LUMOs were dominant on the nanotube surface, whereas the electronic densities in the HOMOs were mainly distributed over the adsorbed SO2 and O3 molecules. Moreover, the charge density difference calculations indicate charge accumulation on the adsorbed gas molecule.

The zeolite N.P./PEG/GO composite was synthesized by hydrothermal assisted sol-gel method to be used as Pb2+ and Cd2+ ions nano-adsorbent from the agricultural water. The FT-IR spectrum confirmed the expected microstructure of synthesized adsorbent. The SEM revealed the formation of zeolite nanoparticles and the layer structure of graphene. The existence of expected elements and crystalline structures were confirmed by EDS and XRD analysis, respectively. The pH, contact time, temperature and adsorption amount was optimized in the removal process of lead (II) and cadmium ions. The results were 6, 20 min, 25 oC and 0.005g for Pb2+ and 4, 20 min, 25 oC and 0.005g for Cd2+ respectively. Adsorption capacity of Lead (II) and cadmium ions were 49.6 and 50.2 mg.g-1 of adsorbent, respectively. Interference ions don’t show any considerable effects on the efficiency of adsorption for both ions. The equilibrium data can well be fixed using both Langmuier and Freundlich equations.