ABSTRACT
In this work, the photocatalytic activity of nanoparticles (NPs) of zinc oxide synthetized by Prosopis laevigata as a stabilizing agent was evaluated in the degradation of methylene blue (MB) dye under UV radiation. The theoretical study of the photocatalytic degradation process was carried out by a Langmuir-Hinshelwood-Hougen-Watson (LHHW) model. Zinc oxide nanoparticles were synthesized by varying the concentration of natural extract of Prosopis laevigata from 1, 2, and 4% (weight/volume), identifying the samples as ZnO_PL1%, ZnO_PL2%, and ZnO_PL4%, respectively. The characterization of the nanoparticles was carried out by Fourier transform infrared spectroscopy (FT-IR), where the absorption band for the Zn-O vibration at 400 cm-1 was presented; by ultraviolet-visible spectroscopy (UV-vis) the value of the band gap was calculated, resulting in 2.80, 2.74 and 2.63 eV for the samples ZnO_PL1%, ZnO_PL2%, and ZnO_PL4%, respectively; XRD analysis indicated that the nanoparticles have a hexagonal zincite crystal structure with an average crystal size of 55, 50, and 49 in the sample ZnO_PL1%, ZnO_PL2%, and ZnO_PL4%, respectively. The morphology observed by TEM showed that the nanoparticles had a hemispherical shape, and the ZnO_PL4% sample presented sizes ranging between 29 and 45 nm. The photocatalytic study showed a total degradation of the MB in 150, 120, and 60 min for the samples ZnO_PL1%, ZnO_PL2%, and ZnO_PL4%, respectively. Also, the model explains the experimental observation of the first-order kinetic model in the limit of low concentrations of dye, indicating the influence of the mass transfer processes.
ABSTRACT
As modern lifestyles and new feeding habits settle in the world, noncommunicable diseases (NCDs) have evolved to be major causes of disability in developing as well as developed countries. As a concomitant effect, there is a growing interest in natural, healthy food and an increasing awareness of risk factors and determinants of disease. This chapter describes some nutritional facts about seaweeds, which have been used as food since ancient times in China, Japan, Egypt, and India and comments on the potential utilization of marine algae as functional foods. This concept and the description of metabolic syndrome are used as a basis to comprehension of seaweeds against two dreadful illnesses of our times: high blood pressure and cancer.
Subject(s)
Functional Food/analysis , Seaweed/chemistry , Humans , Nutritive Value , Oceans and SeasABSTRACT
In order to evaluate the effects of benzo[a]pyrene (B[a]P), a polycyclic aromatic hydrocarbon (PAH) in the sea anemone Anthopleura elegantissima at the biochemical level. NADPH cytochrome P450 reductase and cytochrome P450 were assayed in A. elegantissima under toxicant. One toxicity test was performed with 75 organisms distributed in 5 groups. Animals in groups G1, G2 and G3 were given increasing B[a]P. Two groups named GC and GS were used as controls. GC was treated with seawater and GS was treated with acetone. After 72 h of exposure, enzymatic activities were determined. Microsomes were isolated from the columnar tissue and exposed in vitro to the toxicant in order to explore their ability to incorporate B[a]P. Basal activity for this enzyme was 1.69 +/- 0.18 (Mean +/- standard deviation) nmol cyt C red min(-1) mg(-1) and there was no significant effect in GS organisms compared to GC organisms. Significant increases were observed in NADPH cytochrome P450 reductase in G3 organisms. In this group, the enzyme activity was 3.53 +/- 0.40 nmol cyt C red min(-1) mg(-1). For cytochrome P450 content, a gradual increase was observed in organisms in groups G1 to G3. Basal content was 10.25 +/- 0.49 pmol mg(-1) microsomal protein. For G3 animals, P450 content was 27.51 +/- 0.32 pmol mg(-1) microsomal. For the test in vitro, it was found that microsomes isolated from G2 and G3 had the capacity to incorporate this substance when exposed to B[a]P at a level of 4 mu M in the surrounding medium. Spectrum recorded from 350 to 450 nm after a 40-min exposure for these groups showed significant difference from spectra obtained for microsomes in GC, GS and G1. It was concluded that the capacity to increase NADPH cytochrome P450 reductase activity as well as to increase NADPH cytochrome P450 reductase activity as well as to increase P450 content shows the ability of A. elegantissima to induce a mixed function oxidase activity in the presence of B[a]P.
