The moving die rheometer technique (MDR) is used to measure the elastic and viscous components of rubber. The analysis of the rheometry and the kinetic behavior can be used to obtain mathematical models to predict the viscosity of elastomers as a function of the temperature, the time and the degree of curing. These predictions allow the control, the optimization and the design of the process. In this research the phenomenological model of Kamal-Sourour was used to describe the curing kinetics, while the Carreau Macosko model was used to describe the viscous behavior of an ethylene - propylene diene industrial type compound (EPDM). The mathematical parameters for each model where determined by using non-linear regression techniques. Since the viscosity increases significantly while the curing rate decreases, we proposed a mathematical model based on the Carreau expression in order to consider the influence of the kinetic of curing in the apparent viscosity behavior. It was found that after the curing rate reaches its maximum the viscosity tends to infinity; that is, the chemical transition process known as fluidity point or gel point occurs in the vicinity of maximum curing rate. According to the results, it is concluded that rubber viscosity is well described by considering the curing variations; the fluidity point in the vulcanization process can also be obtained by the practical method of phenomenological approach.

A novel series of copolymers were obtained from the copolymerization of 1-ethynylpyrene (EP) (known as pyrenylacetylene) and ethynylbenzene (EB) (named also phenylacetylene) with WCl6 as catalyst and toluene as solvent, using different monomer molar ratios EP/EB (80:20, 60:40, 50:50; 40:60, 20:80). The optical properties of the obtained copolymers Poly(EP-co-EB) were determined by absorption and fluorescence spectroscopy. Absorption spectra of the copolymers Poly(EP-co-EB) showed that copolymers containing phenylacetylene units possess a lower degree of conjugation than the homopolymer trans-poly(1-ethynylpyrene) (trans-PEP), since they showed a twisted conformation. These results were confirmed by emission spectroscopy showing the formation of excimers for those copolymers containing high pyrene content.

To contribute to the development of new alternatives in the area of polymers for biomedical applications, the surface modification of a cotton gauze grafted with a N-vinylcaprolactam (NVCL) by ionizing gamma radiation was developed, in to provide it with more physical and chemical properties. To verify that the grafting was successful, the samples were analyzed and characterized by attenuated total reflectance, by Fourier transform infrared spectroscopy, differential scanning calorimetry, and thermogravimetric analysis. The grafted samples showed greater hydrophilicity and affinity with drugs, as well as a critical solution temperature between 33 and 40 °C; therefore, this material was implemented as administrator of AgNPs in controlled doses, thus obtaining a material with greater absorption, anti-inflammatory and with antimicrobial characteristics.

The present study investigates the adsorption of fluorides (F) by a hydrotalcite MgFe (HT MgFe) and an iron-based metal oxide (MgFe oxide). Both materials were synthesized by the coprecipitation method and were calcined at the same temperature HT MgFe, HTC MgFe, oxide MgFe and oxide MgFeC. Both solids were characterized by the XRD technique. Materials showed typical crystalline forms; in the case of HT MgFe, an octahedral crystalline form and for the oxide MgFe cubic crystalline form, the analysis of the BET method classifies the materials as mesoporous. In the adsorption study, it was determined that the optimal pH for adsorption is 7. Regarding the adsorption kinetics, the HTC MgFe and oxide MgFeC samples were adjusted to the pseudo-second order model, which describes the process as chemiadsorption; meanwhile, for the samples, isotherms were adjusted to the Langmuir model, which describes the material as homogeneous with a strong interaction between the sorbate and the sorbent.

The use of ALG beads and ALG-ZEO beads for the removal of Cd2+ was evaluated in a batch system, was determined the effect of pH, kinetics and adsorption isotherm. The characterization was carried out by FTIR, SEM and EDS. The EDS analysis showed that the main elements are C, O and Ca, these are associated with the chemical composition of alginate while the ALG-ZEO bead showed characteristic crystals of the zeolite. Cd2+ adsorption was carried out at pH 6 using ALG beads and ALG-ZEO beads as adsorbent. The suggested mechanism to explain the removal of the Cd2+ ion was is through a chemisorption process. Finally the adsorption process was adjusted to kinetic and isotherm models.

Triclosan (TCS) adsorption behavior by a modified zeolite with Cetyl Trimethyl Ammonium Bromide (CTAB) was evaluated factoring in pH, contact time, and TCS initial concentration in a batch system. Natural clinoptilolite-type zeolite from Sonora, Mexico was conditioned with a sodium chloride solution, and, subsequently, modified with CTAB. All the zeolites were characterized by X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Scanning Electron Microscopy (SEM), Electron Dispersive Spectroscopy (EDS), and the Zero Point Charge (pHZPC). It was found that the morphological and structural properties of natural zeolite were not affected after treatment with cationic surfactant. Furthermore, adsorption process efficiency was enhanced by the presence of CTAB, obtaining TCS maximum adsorption capacity at an optimal pH of 9.0. In this context, the positively charged surface of the modified zeolite and the anionic triclosan species present were decisive. Kinetics data were well adjusted to a pseudo-second order model with a TCS adsorption capacity of 1.430 ± 0.051 mg g-1 at an equilibrium time of 18 h. Isotherm results were best adjusted to the Langmuir model with a qmax = 2.027 mg g-1 using an initial Co concentration of 18.0 mg L-1, and reaching an equilibrium Ce concentration of 0.559 mg L-1. The mechanism for the adsorption of TCS by CTAB-modified zeolite was proposed to be electrostatic attractions between the group of partial positive charge of CTAB and the anionic species of triclosan. Consequently, CTAB-modified zeolites could be used as effective adsorbents for triclosan removal.

Metronidazole (MNZ) is an antibiotic drug to be carcinogenic and mutagenic. The present work was focused on MNZ degradation using the Fenton process, in batch studies. Five initial concentrations of MNZ (0.5, 5, 10, 15 and 20 mg/L), three Fe (II) concentrations (2.94, 5.88 and 11.66 μM), 29.4 μM H2O2, and three pH (3.5, 5 and 7) were evaluated at a reaction time of 5 min. A statistical factorial design using the program Minitab 18® was used to study the MNZ degradation. The best experimental conditions to degrade MNZ at 100% was 2.94 μM Fe2+ and pH of 3.5. Three kinetic models were used to study the degradation profile of MNZ at 2.94 μM Fe2+ and 29.4 μM H2O2, such as the first-order, the second-order, and BMG kinetic model. The BMG kinetic model was the best model to describe the MNZ degradation by Fenton process. On other hand, the optimal pH for MNZ degradation was 3.5, independently of the molar ratio Fe2+/H2O2 evaluated. At pH 5, degradation efficiencies decreased significantly, while at pH 7 the lowest degradation of MNZ was observed. Finally, the Fenton process showed the potential to degrade metronidazole.

The heterogeneous catalyst HTCMgFe was used in the degradation of the IC, through the heterogeneous photo-fenton treatment, this material in combination with H2O2 and UV light degraded the dye in 30 min at pH 3. As the amount of HTCMgFe increases the degradation it was accelerated because there are more active catalytic sites of Fe2+ on the surface of the material, which generates a greater amount of •OH radicals. The HTCMgFe was characterized by infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and X-ray energy dispersive elemental analysis (EDS). The UV-vis spectrum shows that the absorption bands belonging to the chromophore group of the IC disappear as the treatment time passes, indicating the degradation of the dye.

In the present work, the photocatalytic activity of metal Fe-Zn nanoparticles was evaluated through the degradation of the synthetic AZO colorant allura red. A Phytosynthesis method developed here takes advantage for the first time of the plant extract of Hydrocotyle ranunculoides as the reducing agent. A fitted Folin-Ciocalteu assay showed about 40% of total polyphenolic compounds used in the nanoparticles generation. UV-Vis and TEM analysis allowed identification of the nanoparticles as oxides of Fe and Zn. Finally, during measurement of the photocatalytic activity a load of 0.5 g/L was applied on a 15 μM solution of allura red as standard model pollutant, while environmental oxygen was used as the initiating agent. Tests showed a 66% degradation of the azo-type dye obeying a degradation kinetics of the first order after short times.

In this study, we reported an environmentally friendly technique for the synthesis of titanium nanoparticles using Eichhornia crassipes leaf extract as a non-toxic reducing agent and efficient stabilizer. Also the antimicrobial activity TiNPs against E. coli. Bacteriological test were performed on solid agar plates with different concentrations of TiNPs. On the other hand TiNPs were characterized by UV-visible spectroscopy, EDS (Dispersive Energy X-ray Spectroscopy), SEM (Scanning Electron Microscopy), and TEM (Transmission Electron Microscopy). It was found that TiNPs exhibit high crystallinity whit rutile titania structure. TEM analysis shows the nanoparticle size in the range from 22 to 44 nm, antimicrobial study was performed by plate count technique witch showed >99% mortality for E. coli bacteria studied after 24 h of incubation.

The purpose of this work was the synthesis of the perovskites with rare earth, by gel combustion method with pigmenting, magnetic and luminescent properties. The synthesis of perovskite structure is important for material development, with multi features. In this work, the synthesis was from metal oxides by the method of combustion of gels at 500 °C, for 10 s. Color of perovskites obtained, with nanometric particle size (31-44 nm) was analysed by CIEL*a*b* with tonalities ranged from white to pink except for Pr-perovskites with yellow and brown. Its paramagnetic properties were verified by magnetic susceptibility. Its luminescence was at 260 nm, except for Pr-perovskites. This work opens an important opportunity to develop ceramic pigments with perovskites structures integrating other properties as luminescence and paramagnetism by combustion sol-gel method.

We present a systematic numerical analysis of the quantum yield of an electric dipole coupled to a plasmonic nanoparticle. We observe that the yield is highly dependent on the distance between the electric dipole and the nanoparticle, the size and permittivity of the nanoparticle, and the wavelength of the incident radiation. Our results indicate that enhancement of the quantum yield is only possible for electric dipoles coupled to a nanoparticle with a radius of 20 nm or larger. As the size of the nanoparticle is increased, emission enhancement occurs at wavelengths dependent on the coupling distance.