Shape memory polymer composites based on a blend of thermoplastic polyurethane (TPU) segmented block copolymer and poly (e-caprolactone) (PCL) with weight ratio of 70.30 and various nanomagnetite contents (0–5 wt%) were prepared by melt blending of TPU and PCL, together with a masterbatch of TPU/nanomagnetite. The samples were compounded for 10 min at 200oC using an internal mixer. Synthesized nanomagnetite powder was introduced to the masterbatch via a solution mixing method using a high-intensity ultrasonic horn. Subsequently, thermal, mechanical, rheological and electrical properties of the TPU/PCL/nanomagnetite shape memory composites were investigated through various tests. The degree of crystallization of the PCL component in the composite structure was inspected by differential scanning calorimetry (DSC) and X-ray diffraction measurements. The results revealed that the percentage of crystallinity and the melting temperature of the PCL component changed in the presence of magnetite nanoparticles, which was related to the nanoparticles acting as nucleants. Observing a single glass transition temperature (Tg) in DSC thermograms of the samples was indicative of good compatibility of the TPU and PCL components in the composite structure. This was also confirmed by dynamic-mechanical analysis in which the loss modulus curves showed a single glass transition temperature. Moreover, the loss modulus peak at glass transition was lowered and broadened by addition of nanomagnetite, by which it was assumed that introducing nanoparticles into the system changed the mechanism of glass transition due to particle–matrix interactions. The dynamic rheological and electrical resistivity experiments verified the existence of a low percolation threshold at about 2 wt% nanomagnetite. The state of nanomagnetite dispersion in the masterbatch and the microstructure of the ternary composites were characterized by scanning electron microscopy. Finally, adding nanomagnetite led to weakening of shape recovery of the polymer blend, with shape recovery dropping to 70% at 5% of nanomagnetite.

Nanomagnetite-Fe3O4 is used as a highly efficient, mild, green and recyclable nanomagnetite catalyst for the synthesis of 4, 4´- (arylmethylene) -bis (3-methyl-1-phenyl-1H-pyrazol-5-ol) derivatives in solvent-free conditions. The condensation of 3-methyl-1-phenyl-1H-pyrazol-5 (4H) -one with aromatic aldehydes affords the title compounds in high yields and short reaction times. The nanocatalyst is reusable for seven times without significant loss of its catalytic activity.

Dielectric barrier discharge technique (DBD) is a new methods for plasma formation which can be used to enhance the oxidation state of different materials. In this study, the probability of enhancing the oxidation state of carbon-based (graphene oxide and multi-walled carbon nanotube) and metal-based (nano-magnetite and nano-alumina) precursors was investigated. In this way, the oxidation state of the materials was evaluated by field emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), Fourier-transform infrared spectroscopy (FT-IR), and ultraviolet-visible spectroscopy (UV-Vis) before and after the plasma process. In addition the dispersity of the nanoparticles in an aqueous solution was investigated by zeta potential method. The obtained results revealed that after the plasma processing, the weight percentage of oxygen element increased about 59% and 33% for graphene oxide and carbon nanotube samples, respectively. However, the metal-based materials were not affected by the plasma process. Indeed, depending on the type of produced oxygen radicals in the plasma space, different groups such as carboxylic acid, hydroxyl, lactone, and lactol groups can be formed on the surface of the carbon-based materials which led to the increasing of the oxidation state of the nanoparticles.

Background and Objectives: With the beginning of the industrial revolution, soil and water pollution by heavy metals has accelerated and efforts to clean and eliminate these pollutants has become one of the major problems of human societies. There are different methods for remediation of contaminated environments and adsorption and immobilization of heavy metals including the use of adsorbents to adsorb heavy metals. In addition to being effective and fast, the immobilization technique is simple, inexpensive, and environmentally safe. In recent years, the use of polymeric composites, among the various adsorbents of heavy metals, has attracted the attention of many researchers due to their higher efficiency in comparison of pure adsorbents. Chitosan composites are among those polymeric composites that, due to their properties, can have a high ability to absorb heavy metals in contaminated environments. Chitosan composites have often been used to remove heavy metals from industrial wastewater, however, the efficiency of these composites in immobilization of heavy metals in soils has not been studied. Due to the great variety and environmental safety of these composites, this study aimed to investigate the efficiency of pure and chitosan coated adsorbents in immobilization of soil cadmium. Materials and Methods: For this purpose, a pot factorial experiment was conducted in greenhouse conditions using a completely randomized design and three replications. Factors studied were soil cadmium levels (0, 8, 25 and 75 mg/kg soil) and types of adsorbent including pure chitosan, biochar, zeolite and nanomagnetite and composites of chitosan-biochar, chitosan-zeolite and chitosan-magnetite and control (without adsorbents). Each adsorbent was applied to soil at the rate of 0. 5% W/W. Uncontaminated soil samples were spiked with different amounts of cadmium sulfate and incubated for two months to achieve relative equilibrium. After two months the samples were treated with different adsorbents and incubated for another two months. Then, the amounts of DTPA extractable cadmium and its different chemical forms were determined. Results: The results showed that the application of adsorbents to soil decreased the concentrations of DTPA extractable cadmium. The results also showed that chitosan composites had higher ability for immobilization of cadmium in the soil than the pure chitosan, biochar, zeolite and nanomagnetite and the highest cadmium immobilization ability was observed for the composite of chitosan-magnetite. Reductions in DTPA-extractable cadmium for pure chitosan, biochar, nanomagnetite, and zeolite were 26. 11, 19. 38, 18. 00 and 7. 71% and for composites of chitosan-magnetite, chitosan-biochar and chitosan-zeolite were 34. 02, 32. 04 and 30. 56%, respectively when compared to the control treatment. Sequential extraction at the contamination level of 75 mg Cd/kg soil also showed that the use of adsorbents significantly reduced the soluble + exchangeable and carbonate forms of cadmium compared to the control treatment and increased its more stable forms including iron and manganese oxide, organic matter and residue fractions. Conclusion: According to the results, it can be concluded that coating the pure adsorbents with chitosan by creating more adsorption sites reduces the cadmium mobility in the soils and increased the efficiency of pure adsorbents in the immobilization of cadmium. It was also observed that among the composites that used in this experiment, the highest ability to reduce the cadmium concentration was related to the chitosan-magnetite composite.

In this study the efficiency of magnetic nanoparticles for removal of trivalent arsenic from synthetic industrial wastewater was evaluated. The nanoparticles was prepared by sol-gel method and characterized by X-ray methods including XRD, XRF, and SEM, and vibrating sample magnetometer (VSM). The results showed that synthesized nanoparticles were in the size range of 40-300 nm, purity of about 90%, and magnetization of nanoparticles was 36.5emu/g. In initial conditions including: pH=7, As (III) concentration of 10 mg/L, nanomagnetite concentration of 1g/L, shaking speed of 250 rpm and 20 minute retention time, 82% of As (III) was removed. Competition from common coexisting ions such as Na+, Ni2+, Cu2+, SO42-, and Cl- was ignorable but for NO3- was significant. The adsorption data of magnetite nanoparticles fit well with Freundlich isotherm equations. The adsorption capacity of the Fe3O4 for As (III) at pH=7 was obtained as 23.8 mg/g. It was concluded that magnetite nanoparticles have considerable potential in removal of As (III) from synthetic industrial wastewaters.