Journal of Applied Research in Chemistry
Year:2014 | Volume:8 | Issue:3|Papers Count:9

Quantitative recovery of terephthalic acid (TPA) from poly (ethylene terephthalate) (PET) wastes is reported under controllable microwave irradiation in the presence of diethylene glycol (DEG) as the solvent in combination with NaOH and nano-Fe3O4@SiO2 as the catalyst and solid support, respectively. The reaction was performed in mono-mode microwave reactor and the weight ratios of DEG: PET, NaOH: PET and nano-Fe3O4@SiO2:NaOH were investigated in detail. Obtained results revealed that in the presence of NaOH (0.4 g), nano-Fe3O4@SiO2 (1 g) and PET: DEG molar ratios (1:6), TPA was obtained in high recovery yield (96%). At the end of the reaction, nano-Fe3O4@SiO2 was recovered by simple magnetic decantation and reused for several times without observing significant decrements in TPA recovery yields.

The preparation of nano-structured silica has opened a wide field of applications since 1992 until now. In comparison with other nano-structured silica materials, SBA-15 exhibits thicker pore wall, higher pore volumes, and wider pores. The silica wall surface of nanoporous silica can be modified with organic groups to tailor their properties and achieve specific purposes. Among the main uses of nanoporous silica, it is well-known the design of adsorbents for environmental clean up and many reports can be found. Removal of dyes from aqueous solutions is one of the major problems in wastewater treatment, since they are mostly toxic. Malachite green, a triphenylmethane dye, has been widely used for the dyeing of leather, wool, and silk as well as used as a fungicide and antiseptic in aquaculture industry to control fish parasites and disease. But recently, MG has been found exhibiting carcinogenic, genotoxic, mutagenic, and teratogenic properties, and so the use of MG by the FDA is forbiddened, In this study MG removed from waste water by using this carboxylic functionalized SBA-15 and the isotherm diagrams and its kinetic were studied. BET adsorption/desorption isotherm showed 603, 277, and 252 m2g-1 surface area for SBA-15, SBA-15-NH2, and SBA-15-COOH, respectively. Reduced surface area was related to step by step mesoporous functionalization. Isotherm study was done. Isotherm data obeyed the Freundlich model so that multi-layer adsorption of MG on SBA-15-COOH was expected. In comparison with two other adsorbent SBA-15-COOH led to a better result. SBA-15-COOH kinetics data for adsorption model obey semi-first order model.

In the present study, the adsorption behavior of an impregnated resin (Ambrlite XAD-4 / Cyanex 301) in the presence of La (III), Sm (III), Ce (III), Gd (III), Dy (III), Nd (III) and Lu (III) ions were examined in aqueous media. In order to prepare impregnated resin, a desired amount of Cyanex 301 was diluted with ethanol at 1:1 volume ratio and then impregnation process was performed in a shaker with speed of 100 rpm at 25oC during 24 hours. After separating the resin from the solution by filter paper, it was placed in an oven at 40oC for 48 hours. The amount of impregnated Cyanex 301 was determined to be 49 percent. The kd values of metal ions were determined under various pH, nitric acid, temperature and different amount of the adsorbent. To determine the amounts of metal ions, an inductively coupled plasma (ICP-AES) was used. The results showed that the maximum uptake for some heavy lanthanides such as Dy (III) and Lu (III) were take placed at the pHs less than 4.8 while for La (III) and medium lanthanides, the maximum uptake values were observed in pH=5.1 and 4.3, respectively. Such behavior shows that it is possible to separate light lanthanides from heavy ones using the variation of pH. Based on these kd results, it can be concluded that the lanthanides uptake decrease with increasing acid concentration.

In this study, the effect of ceria as a promoter on the performance of synthesized nanostructured mixed oxides has been investigated in the steam methanol reforming process. Urea nitrate combustion method is recommended as a novel, rapid, and simple process to achieve nanoporous structure. Synthesized nanostructured mixed oxides, after shaping, were evaluated in catalytic performance study system at 200-300oC temperature range under atomospheric pressure. The phsycochemical properties of synthesized nanostructured mixed oxides were studied by XRD, FT-IR, FESEM, BET, and SEM-EDX analyses. CuO and ZnO were detected in XRD patterns and alumina presence was proved via SEM-EDX and FT-IR since no peaks could be detected in XRD patterns. FESEM images showed that particles of synthesized samples were in nano range. It was seen that relative christallinity decreased slightly. Catalytic performance study showed that ceria increased methanol conversion and hydrogen selectivity while decreased selectivity of CO and CO2 as undesired products.

In this paper, a new method is described for the preparation of hydrophobic silica nano-coating on glass surfaces at room temperature, by applying tetrametoxysilane (TMOS) as a precursor and octadecyletrichlorosilane (OTS) as a surface modifier through a dipping method. By changing the mole ratio of OTS/TMOS, the efficiency of surface hydrophobicity modifies with coating. The best coating performance was obtained for NH3, OTS, TMOS, and MeOH with mole ratio of 8: 1.4: 1: 14.8, respectively. The water contact angle by of the hydrophobic glass surface reaches to 132 degree. Nano coating particle sizes is estimated to 2-29 nm by the DLS method. Experimental results show that hydrophobic silica film retains its hydrophobicity up to 200oC, but at higher temperatures loses this property. Besides determination of contact angle and particle size distribution, prepared nanoparticles are characterized by UV-Vis, FT-IR and TEM methods. Applying both TMOS and OTS and achieving water contact angle of 132 degree for modified glass surfaces are the novelties of this work.

In this study, the core shell structures with SPION cores and PAMAM shells were synthesized. Super-paramagnetic iron oxide nanoparticles (SPION) prepared by coprecipitation of FeSO4.7H2O and FeCl3.6H2O with NH4OH. The surface of nanoparticles functionalized by 3- amino propyl tri ethoxy silane (APTES), and finally 3G polyamidoamine (PAMAM) dendrimers were coated on the surface of functionalized nanoparticles. The samples were characterized by X-ray diffractometry (XRD) and Fourier transform infrared (FT-IR) spectroscopy. The behavior of dendrimer shell was analyzed by thermal gravimetric analysis and SPION core properties were characterized by Vibrating Sample Magnetometer s (VSM). XRD results confirmed the high purity magnetite, where peak density decreases with coating of dendrimer. The particle size obtained by Debye- sherre measurement was 10.3 nm and 14.3 for SPION, and dendrimer coated SPION respectively. FT-IR spectra of PAMAM-grafted nanoparticles also verified the functionalization and polymerization on the surface of the nanoparticles. TGA weight change results showed that the weigh loss was 8.2 % and 59.14 % of initial weigh for zero generation and 3.5 G denderimers, respectively. Maximum saturation magnetization is 67.9 for magnetite nanoparticles and 60.5 for core-shell structure with 3.5 G dendrimer shell, which confirms the super-paramagnetic properties of synthesized structure.

Mordenite is a high silica zeolite which is synthesized from a gel with different oxide molar ratios at various temperatures. The zeolite is widely used as adsorbents in the separation of gas or liquid mixtures and also as catalysts for naphtha and xylene isomerization in petroleum industries and petrochemical complexes. Mordenite crystallites with the size of 77-93 nm were hydrothermally synthesized from a gel with the different oxide molar ratios (Na2O/Al2O3 = 1-2.5 and SiO2/Al2O3 = 10, 16) aged at 30oC for 0 to 3 days in a Teflon lined autoclave at crystallization temperatures of 155 and 175oC. Different techniques like XRD, FT-IR, SEM, BET, and EDX were used to characterize the as-synthesized zeolite samples and to analyze their physicochemical properties as well. Results obtained from the present work illustrated that the nano-sized mordenite zeolites with rod (high aspect ratio) and ellipsoidal morphologies were synthesizable with the gel compositions mentioned above. Preparation of such uniform morphologies for mordenite from the gel compositions used in this work in the absence of an organic template has not been yet reported.

Heavy metals are toxic for human and animals. Industrial wastewater streams containing heavy metals are produced from different industries. Clinoptilolite (CP) (Iranian domestic Natural Zeolite) was modified by titanium oxide and iron oxide nanoparticles using solid-state dispersion (SSD) method. These nanoparticles of the adsorbent were characterized by BET, XRD, SEM, and EDS. Various factors affecting the uptake behavior such as contact time, initial concentration of Pb2+, dosage TiO2-Fe3O4/CP, pH, temperature, and shaker rate were investigated. The maximum effect of adsorbent was observed at 5 wt. % TiO2, 5 wt. % Fe3O4, and 90 wt. % Clinoptilolite. The equilibrium data were analyzed using Freundlich and Langmuir isotherms and the Langmuir adsorption capacity was found to be 109.89mgg-1. Thermodynamic parameters showed that the adsorption process was endothermic from 283 to 313 K, then it was exothermic from 323 to 333 K. The kinetics followed is first order in nature, and the value of rate constant was found to be 0.0093 min-1 at 100 ppm and 303 K.