javad saien

In this investigation, a novel type of zinc oxide supported on clinoptilolite zeolite ZnO /Clinoptilolite (ZnO/CP) nanophotocatalyst was prepared based on the solid-state dispersion (SSD) method. The prepared nanophotocatalyst was characterized with XRD and SEM techniques. As an application, the photocatalytic degradation of malachite green dye in water under UV irradiation was studied. The results show that the ZnO /CP is an active photocatalyst and the maximum effect of photodegradation was observed at 10 wt.% ZnO, 90 wt% Clinoptilolite. A first-order reaction with K = 0.0075 min-1 was concluded. The effects of some parameters such as pH, amount of photocatalyst, and temperature were also examined. Finally, a mechanism was introduced for MG photodegradation.

During recent years, Gemini ionic liquids (ILs), as a new type of surfactants, have gained much attention due to their significant interfacial activity. Accordingly, use of these materials to reduce crude oil-water interfacial tension (IFT) and to enhance oil recovery is much advantageous. In this study, effects of concentration, temperature and pH on the crude oil-water IFT in the presence of Gemini IL surfactants were investigated. For this aim, alkyl chain length imidazolium based gemini ILs of [C4im-C4-imC4][Br2] and [C8im-C4-imC8][Br2] were synthesized and used. By measuring IFT of the system, under different conditions, the corresponding variations were considered. Results revealed the strong effect of alkyl chain length and concentration on the IFT, leading to, respectively, 72.5 and 97.5% reductions under critical micelle concentrations and temperature of 298.2 K. The Gemini IL surfactants were stable at high temperatures and under a wide range of pH, and that their performance was significantly promoted with these factors. In theoretical investigation, it was revealed that the experimental data were nicely consistent with the Frumkin adsorption isotherm and the obtained parameters with reasonable variations.

The mesalazine and fluvoxamine drugs were grafted to single-walled carbon nanotubes (SWCNTs) for the aim of precise drug delivery. First, carboxylic groups in SWCNT were converted to corresponding acyl chlorides. Next, to attain the formation of amide bonds, acyl chloride-SWCNTs were mixed with chemotherapeutic agents, having NH2 and NH functional groups. Then, the covalently grafted drugs to SWCNT were characterized by UV- visible, IR spectroscopy, and transmission electron microscopy (TEM) methods. Finally, the prepared organic compounds were used for releasing drugs at pH: 1.3, which is corresponding to clinical aspects of the human body, and were examined for the potential of drug delivery in patients. Accordingly, the in-vitro kinetic as well as the mechanism of the released drugs were investigated.

Background & Aims of the Study: Chromium is widely detected in surface waters and underground waters, which usually appear as Cr(VI), and Cr(III), at sites associated with industrial activities. Cr(VI), in effluent streams with a high level of mobility and notorious mutagenic and carcinogenic toxicity; thus Cr(III) does not have much mobility in soil. So, converting it into less harmful species could be beneficial.
Cr(VI) photocatalytic reduction in aqueous media was analyzed using desperately low dosages of nanoparticles of commercial titania. A directly imposed irradiation photoreactor equipped with a supersonic source was applied. The optimization of the reduction process was done using the central composite design (CCD) experimental. The residual concentration of Cr(VI) ion was determined by colorimetrically method. In addition, the impact of other factors, including water matrix and hole scavengers, also reduction kinetics were studied.
A quadratic equation for reduction efficiency was proposed, and the adequacy of it was evaluated by a variety of statistical methods. A maximum of 80.6% reduction in aqueous samples containing an initial concentration of Cr(VI) within the investigated optimum operating condition (TiO2 dose of 33 mg/L; pH of 2.5, T=35 and t=120 min) was obtained. Results indicate that UV irradiation alone is an acceptable method for Cr(VI) reduction maybe due to H2O2 photolytic generation. The results show Cr(VI) photoreduction was greatly enhanced by about 88.2% when NO3− was used in comparison with SO42− anion. The photoreduction enhancements with the scavengers are appeared in the following order ethylene glycol > formic acid > citric acid with relevant. Maximum reduction of 96.5% for Cr(VI) was obtained in the presence of ethylene glycol hole scavenger. The results indicated that the process rate can be presented with a pseudo-first-order kinetic model.
The results showed, the CCD design was approximately adequate in Cr(VI) reduction, so it can be a suitable option for water quality improvement. The addition of inorganic or organic species can act as scavenging hydroxyl radicals- which are photo-generated- and valanceband holes that are on the photocatalysts of the semiconductor, and consistently, enhance the photocatalytic reduction of Cr(VI) ion.

Heavy metals in aquatic systems usually interfere with many beneficial uses of water. Divalent nickel is a commonly occurring toxic metal in natural ecosystems due to the effluent of refineries, electroplating, and casting industries. In aquatic environments, nickel appears as Ni (II) and Ni0. Despite the high reported toxicity for Ni (II), Ni0 is only slightly toxic. Various methods have been proposed for the treatment of aqueous solutions containing Ni (II). Photocatalytic reduction is an important process; titanium dioxide has been mostly used as a very efficient photocatalyst. In this study, the removal of divalent nickel ions in aqueous solutions was studied in the presence of remarkably low dosages of nano-titania photocatalyst. Direct imposed irradiation was utilized for treatment of solutions. Accordingly, the influence of four operational parameters, including temperature within the conventional range of 20 to 40 °C, was investigated. Design of experiments, modeling and process optimization were accomplished using central composite design of response surface methodology. Reduced quadratic expression was developed for the reduction efficiency (RE), and the analysis of variance showed its capability in reproducing the data. The effectiveness of each parameter was determined. At the best found conditions of [TiO2] = 42 mg/L, pH = 9.2, T = 34 °C and after 90 minutes of treatment, about 85% removal was achieved for initial 5 mg/L nickel solutions. Pseudo first order reactions proceeded. Based on CCD method, the influence of individual operating parameters and their interactions were obtained. A quadratic equation predicted the variations quite well.