نشریه شیمی کاربردی روز
پیاپی 30 (بهار 1393)

In this work we intend to recovery of benzoic acid from residue formed in crude terephthalic acid production process in the Tondgooyan Petrochemical Company. In this process is produced a large amount solid residue in addition to terephthalic acid. Analysis results shows this residue contains of benzoic acid، crude terephthalic acid، p-toluic acid and small amounts of catalysts. Benzoic acid containing residue recycled by recrystallization in water because of benzoic acid have a very high solubility in hot water and a low solubility in cold water. Effective variables on recrystallization process is dilution ratio of water to residue، dissolve and crystallization temperature of benzoic acid in water. The Optimum conditions of recrystallization consist of dilution ratio of water to residue 4 to 1، dissolve and crystallization temperature is 95 and 25 C° respectively. Recovery yield of benzoic acid is 85 percent in optimum conditions of recrystallization. Purity of recovered crystals of benzoic acid is 97. 79 percent. Because of recovered benzoic acid have a high purity، it may applied in different industries.

Tangstophosphoric acid (H3PW12O40) as an acidic catalyst has been used for facile synthesis of xanthene derivatives by the reaction of α،α′-bis (substituted-benzylidene) cycloalkanones and dimedone in solvent-free conditions. Avoiding the use of toxic solvents، short reaction time، easy work up and high yields of products are the advantages of this procedure.

Every day growth of population and industrial activities in recent decades causes to enter excessive amount of pollutants to water resources. Among these pollutants، textile industry’s dyes should be noted which exist in abundance in the sewage. Considering the toxicity of the pollutants، their removal from water resources is necessary. In this research، removal of high demanded dye، reactive red 74، from aqueous solution by zinc oxide nanoparticles was investigated and the affecting parameters such as solution pH، contact time، and sorbent mass on the removal efficiency were determined. In addition، isotherm and kinetic model of the adsorption process were studied. The results showed that the pseudo-second order kinetic equation could best describe the adsorption kinetics and the adsorption process well correlated with Langmuir isotherm.

In this research، surface tension and surface properties of binary mixtures of water with a series of aliphatic carboxylic acids (C1-C4) were investigated by different models at temperature range between (288. 15 and 328. 15) K. Correlating of the surface tension of the above mentioned binary systems was performed with empirical and thermodynamic based models. In the present work، for the surface tension correlation we used the following models: Redlich-Kister (RK)، Li et al. (LWW)، Fu et al. (FLW) and Myers-Scott (MS). In addition to finding more information about the surface structure of binary mixtures، surface mole fraction was calculated using an extended Langmuir model (EL). The results provide information on the molecular interactions between the unlike molecules that exist at the surface and the bulk.

In this study، the effect of methyl methacrylate on the stability of the emulsion system and its distribution in water- toluene system، half decay time، surface tension by drip method and critical micelle concentration by conductometry method were investigated. The results showed that، the monomer in the presence of anionic surface active agent cause a decrease in critical micelle concentration. The critical micelle concentration in the mixture of water-toluene-SDS-MMA emulsion system، due to high solubility of monomer in toluene، was decreased. Meanwhile، the electric conductivity and half-decay time in the presence of monomer-surfactant was increased.

Indoles are one of the most prevalent heterocyclic compounds، which are present as the basic cores in many natural products potent pharmaceutical compounds. Despite numerous diverse approaches toward the synthesis of indoles developed so far، it is still challenging to prepare indoles with various substituents from readily available compounds. In this approach، nano-Fe3O4 been applied as a catalyst for one-pot synthesis of 3-aminoalkylated indoles in solvent-free conditions. This method offers some advantages in terms of short reaction times، easy work-up procedure، high yields and mild conditions. These products were evaluated in vitro for their antibacterial activities.

Over the last decade، metal-organic frameworks have been widely used as new options for hydrogen storage. The high surface area and regular pores cause these materials are good options for hydrogen storage. In this study sodium ions were introduced in (Cu3 (BTC) 2)MOF-199 holes with in situ method، and its hydrogen adsorption performance was measured at room temperature. The structure and morphology of the proposed new MOF ((Na. Cu3(BTC) 2)) was recognized with various techniques including TG، BET، SEM، FTIR and XRD. The results showed that after introducing sodium ions in the MOF، the main structure did not changed and the surface area increased from 1300 m2g-1 to 1434 m2g-1 and the hydrogen adsorption increased from 1 to 1. 4 wt% (40% increase). The increase in hydrogen adsorption after sodium doping may be due to growing surface area and physical interaction between hydrogen molecules and sodium ions (increasing binding energy). Therefore، sodium ions act as additional sorption sites and adsorb hydrogen molecules.

In recent years، steam reforming of methanol has been attracted more attentions، because this process produces hydrogen as clean fuel that useful for fuel cells. In this study the influence of precursors of Al2O3 in CuO/ZnO/Al2O3 nanocatalyst preparation by the combustion method was studied. The nanocatalysts properties are evaluated by employing different kinds of analysis techniques such as XRD، FESEM، EDX، FTIR and BET. The results illustrated that precursor type has significant influences on phase structure، morphology، surface area and functional groups. XRD analysis showed that the nitrate based nanocatalyst has smaller CuO crystals with better dispersion. Also FESEM analysis confirmed the nanocatalyst with nitrate based alumina has homogeneous and nano particles in comparison to the nanocatalyst with AlOOH based alumina. Evaluation of CuO/ZnO/Al2O3 nanocatalyst showed nitrate based sample due to mentioned well-defined structure had superior activity in feed conversion than similar AlOOH based catalyst.

In this article، a novel method that utilizes N،N′- bis (5- boromo salicyliden) 2،2- dimetyl 1،3- propan diamine- modified activated carbon as a solid-phase extractant has been developed for simultaneous preconcentration of trace Cu2+، Pb2+and Fe2+ prior to the measurement by flame atomic absorption spectrophotometry. Experimental conditions for effective adsorption of trace levels of Cu2+، Pb2+and Fe2+ were optimized using batch and column procedures in detail. The optimum pH value for the separation of metal ions simultaneously on the new sorbent was 5 and the adsorbed metal ions could be completely eluted by using 6. 0 mL 4. 0 molL−1 HNO3 solution. Common coexisting ions did not interfere with the separation and determination of target metal ions. The maximum static adsorption capacity of the sorbent at optimum conditions was found to be. 8، 39. 9،77. 8 and 17. 3mgg−1 for Cu2+، Pb2+and Fe2+، respectively. The detection limits of the method were found to be 1. 47، 3. 1 and 2. 65 µgL−1 for Cu2+، Pb2+and Fe2+ respectively. The relative standard deviation (RSD) of the method was lower than 4. 0% (n = 8). The method was successfully applied for the preconcentration of trace Cu2+، Pb2+and Fe2+ in natural and certified samples with satisfactory results.