Contaminants, organic or inorganic, represent a threat for the environment and human health and in recent years their presence and persistence has increased rapidly. For this reason, several technologies including bioremediation in combination with nanotechnology have been explored to identify more systemic approaches for their removal from environmental matrices. Understanding the interaction between the contaminant, the microorganism, and the nanomaterials (NMs) is of crucial importance since positive and negative effects may be produced. For example, some nanomaterials are stimulants for microorganisms, while others are toxic. Thus, proper selection is of paramount importance. The main objective of this review was to analyze the principles of bioremediation assisted by nanomaterials, nanoparticles (NPs) included, and their interaction with environmental matrices. It also analyzed the response of living organisms employed to remediate the contaminants in the presence of nanomaterials. Besides, we discuss the international regulatory frame applicable to these technologies and how they might contribute to sustainability.
Soot particles have been associated with respiratory diseases and cancer. To decrease these emissions, perovskite-mixed oxides have been proposed due to their thermal stability and redox surface properties. In this work, SrTiO 3 doped with different amounts of Mn were synthesized by the hydrothermal method and tested for soot combustion. Results show that at low Mn content, structural distortion, and higher O ads /O lat ratio were observed which was attributed to the high content of Mn 3+ in Ti sites. On the other hand, increasing the Mn content led to surface segregation of manganese oxide. All synthesized catalysts showed mesopores in the range of 32-47 nm. In the catalytic combustion of soot, the samples synthesized in this work lowered the combustion temperature by more than 100 • C compared with the uncatalyzed reaction. The sample doped with 1 wt % of Mn showed the best catalytic activity. The activation energy of these samples was also calculated, and the order of decreasing activation energy is as follows: uncatalyzed > Mn0 > Mn8 > Mn4 > Mn1. The best catalytic activity for Mn1 was attributed to its physicochemical properties and the mobility of the oxygen from the bulk to the surface at temperatures higher than 500 • C.
The changes occurring during the depolymerization of lignocellulosic biomasses are not yet fully understood. Synchrotron micro-Fourier transform infrared (m-FTIR), Raman spectroscopy (RS), X-ray diffraction (XRD), and X-ray fluorescence (XRF) were applied for better characterization of wheat straw fibers during a continuous pretreatment process in terms of conditioning (C), extrusion (E), steam explosion (SE), and enzymatic hydrolysis (EH). m-FTIR revealed functional groups as phenylpropanoid polymers, ethers, and aliphatic alcohol. RS detected acetoacetate, methyl and phenol groups after SE. The crystallinity index and silica content were also determined.
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