In this Research, tin)II( oxide doped with GRAPHENE )SnO /GRAPHENE( nanocomposite was synthesized by hydrothermal method. Structural characteristics of the nanocomposites were studied using X-ray Diffraction )XRD(, Energy-dispersive X-ray spectroscopy )EDS( scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR), to confirm possible interactions which may have formed between the nanocomposites. Then, SnO /GRAPHENE nanocomposite was used as a sensitive and active layer for preparing a gas sensor for ethanol gas sensing. To optimize the condition and function of the sensor, the sensitivity and response of the nanocomposite at working temperature were investigated and important parameters such as response time, recovery time, and selectivity were determined. At the working temperature also at operating temperature, the sensor showed a sensitivity of about 12 times the concentration of 200 ppm and its response time was significantly lower. In addition, the SnO /GRAPHENE sensor had good selectivity over the target gas compared to other gases such as methanol, phenylethyl alcohol, acetone, n-hexane, etc. Due to the properties of bamboo charcoal and specific surface properties and its porosity structure, tin )II( oxide doped with bamboo charcoal )SnO/Bamboo charcoal( nanocomposite synthesis, this sensor was also studied. SnO/Bamboo charcoal nanocomposite showed a significant sensitivity to the low concentration of ethanol at 10 ppm which is better than the sensitivity and detection limit compared to SnO /GRAPHENE sensor.

In this research, Fe3O4 and Fe3O4/GRAPHENE materials were prepared and characterized via different techniques such as X-ray diffractometer (XRD), Vibrating Sample Magnetometer (VSM), and energy-dispersive X-ray spectroscopy (EDX). The efficiency of prepared samples were investigated by elimination of methylene blue as a cationic dye from aqueous solutions via different methods such as adsorption, photodegradation and sonodegradation processes. The results indicated that the degradation rate of methylene blue by Fe3O4/GRAPHENE nanocomposite under sonocatalytic process was considerably higher than the adsorption and photocatalytic procedures. Sonocatalytic degradation of methylene blue by Fe3O4/GRAPHENE nanocomposite could be explained by the mechanisms of hot spots and sonoluminescence. The degradation pathways between sonocatalytic oxidation and methylene blue solution was described. The results showed that the conjugate structure of nitrogen-sulfur heterocyclic material was broken and aromatic ring was oxidized to open the ring. Methylene blue molecules were finally mineralized to H2O and CO2 in the sonocatalytic degradation process. Furthermore, the figures-of-merit based on electric energy consumption (electrical energy per order (EEO)) were estimated in the degradation of methylene blue in the presence of Fe3O4/GRAPHENE nanocomposite. The results showed that less energy is consumed during the sonodegradation of methylene blue in the presence of Fe3O4/GRAPHENE nanocomposite in comparison with photodegradation procedure.

In this study, the effect of Fe3O4-coated GRAPHENE as nanocatalyst on the kinetics degradation of Ammonium Perchlorate and Glysydyl Azide Polymer (AP/GAP) composite propellants is investigated in order to modify and improve the burning rate of propellants. The SEM-EDX and EDX-Mapping surface analysis methods were used for structural and morphological study of the propellant containing nanocatalyst. The results showed that all the samples were homogenous. Thermal analysis techniques (DSC and TG) were used in the presence and absence of the nanocatalyst in order to investigate the thermal behavior of the propellant. The results showed that GRAPHENE@Fe3O4 reduces decomposition temperature and merge decomposition peaks of AP. This will probably speed up the process of thermal decomposition of AP in the propellant. Moreover, the thermal decomposition kinetics of the samples were investigated using TGA analysis data and Friedman, Ozawa, and Flynn-Wall-Ozawa (FWO) methods. Then the activation energy of the samples were calculated. The results showed that the required activation energy in the presence of GRAPHENE@Fe3O4 was less than in the absence of the catalyst, improving the performance of propellant.

In this research work, TiO2, TiO2-GRAPHENE, and TiO2-GRAPHENE/Alginate catalysts were synthesized and characterized by different methods such as XRD, TEM, SEM, and EDX analysis methods. Photocatalytic activity of prepared samples was investigated by photocatalytic removal of malachite green and methyl orange as cationic and anionic dyes from aqouse solutions. The results showed that photocatalytic activity of samples depends on the chemical structure of pollutants. TiO2-GRAPHENE/Alginate nanocomposite showed higher photocatalytic activity on the removal of cationic dye from aqouse solutions. While TiO2-GRAPHENE sample showed higher photocatalytic activity on the removal of anionic dye from aqouse solutions comparison. The figures of merit based on electric energy consumption (electrical energy per order (EEO)) were evaluated in the photodegradation of malachite green in the presence of prepared samples. The results indicate that less energy is consumed during the degradation of malachite green in the presence of TiO2-GRAPHENE/Alginate compared with other photocatalysts. To understand the nature of adsorption process, the equilibrium adsorption isotherms were studied. Based on results, for TiO2-GRAPHENE/Alginate, Langmuir isotherm model with correlation coefficient of 0. 995 fitted the experimental data, respectively. According to the Langmuir isotherm model, the maximum adsorption capacity of TiO2-GRAPHENE/Alginate for adsorption malachite green was about 86. 45 mg. g^(-1), which was about 4 times the adsorption capacity of Ag-TiO2. Also, recyclability of TiO2-GRAPHENE/Alginate nanocomposite was investigated. The results showed that TiO2-GRAPHENE/Alginate nanocomposite with recycling ability is highly stable.