White Light-Photolysis for the Removal of Polycyclic Aromatic Hydrocarbons from Proximity Firefighting Protective Clothing.

The presence of polycyclic aromatic hydrocarbons (PAHs) on firefighters' personal protective equipment is a concern. One form of preventing from these compounds is to decontaminate proximity firefighting protective clothing (PFPC). Traditional decontamination methods do not promote total removal of pollutants and alter the properties of PFPC. The objective of this work was to evaluate the effectiveness of white light-photolysis (WLP), an advanced oxidation process (AOP), for removing PAHs from PFPC, while maintaining the integrity of the fabric fibers. Experiments were carried out, varying reaction time and concentration of H2O2. With WLP (without H2O2), it was possible to remove more than 73% of the PAHs tested from the outer layer of PFPC in 3 days. The WLP provided the greatest removal of PAHs, compared with the most common mechanical decontamination techniques (laundering and wet-soap brushing). The fibers' integrity after exposure to the white light was evaluated with infrared spectroscopy and scanning electron microscopy/energy dispersive X-ray spectrometry. In addition, a tearing strength test was performed. No remarkable fabric degradation was observed, indicating a possible, routine-compatible, simple, and inexpensive method of decontamination of PFPC, based on photolysis, which is effective in the degradation of PAHs and maintains the integrity of fabric fibers.

Evaluation of an Ozone Chamber as a Routine Method to Decontaminate Firefighters' PPE.

Ozone chambers have emerged as an alternative method to decontaminate firefighters' Personal Protective Equipment (PPE) from toxic fire residues. This work evaluated the efficiency of using an ozone chamber to clean firefighters' PPE. This was achieved by studying the degradation of pyrene and 9-methylanthracene polycyclic aromatic hydrocarbons (PAHs). The following experiments were performed: (i) insufflating ozone into PAH solutions (homogeneous setup), and (ii) exposing pieces of PPE impregnated with the PAHs to an ozone atmosphere for up to one hour (heterogeneous setup). The ozonolysis products were assessed by Fourier Transform Infrared Spectroscopy (FTIR), Thin-Layer Chromatography (TLC), and Mass Spectrometry (MS) analysis. In the homogeneous experiments, compounds of a higher molecular weight were produced due to the incorporation of oxygen into the PAH structures. Some of these new compounds included 4-oxapyren-5-one (m/z 220) and phenanthrene-4,5-dicarboxaldehyde (m/z 234) from pyrene; or 9-anthracenecarboxaldehyde (m/z 207) and hydroxy-9,10-anthracenedione (m/z 225) from 9-methylanthracene. In the heterogeneous experiments, a lower oxidation was revealed, since no byproducts were detected using FTIR and TLC, but only using MS. However, in both experiments, significant amounts of the original PAHs were still present even after one hour of ozone treatment. Thus, although some partial chemical degradation was observed, the remaining PAH and the new oxygenated-PAH compounds (equally or more toxic than the initial molecules) alerted us of the risks to firefighters' health when using an ozone chamber as a unique decontamination method. These results do not prove the ozone-advertised efficiency of the ozone chambers for decontaminating (degrading the toxic combustion residues into innocuous compounds) firefighters' PPE.

Organic load removal and microbial disinfection of raw domestic sewage using SrSnO3/g-C3N4 with sunlight.

Sewage treatment and water reuse are, undoubtedly, one of the main points on scientific agenda of the 21st century. Many technologies for sewage treatment are available; however, it is still as an open issue that deserves much attention in order to facilitate their application, develop more effective methods and propose alternative treatment for unusual situations. Developing high performance materials for sewage treatment fits the idea of the development of efficient and alternative methods for microorganism removal and the high organic load of wastewater and is of fundamental importance. In this paper, a heterojunction with perovskite-type strontium stannate (SrSnO3) and graphitic carbon nitride (g-C3N4) - SrSnO3/g-C3N4 - was synthesized and used for photocatalytic treatment of domestic sewage using only sunlight. Results were accompanied by assessing the total organic carbon decrease and removal of pathogenic microorganisms. X-ray diffraction and X-ray excited photoelectron spectroscopy demonstrated that a heterostructure was successfully formed and photocatalytic tests showed an important activity in the visible range, i.e., under sunlight. Exposing raw sewage to 240 min (from 11 a.m. until 3 p.m.) in the presence of SrSnO3/g-C3N4, led to a 56.1% mineralization. This process was 2.5 more efficient than photolysis under sunlight. Moreover, the treated sewage showed no coliform growth (either fecal or total) or heterotrophic bacteria. This simple treatment makes sewage suitable and safe for reuse, for example, for agriculture purposes according to Brazilian regulations criteria and could be an alternative for isolated areas in which sewage treatment plants are not available.

Toxicological study of the degradation products of antineoplastic agent etoposide in commercial formulation treated by heterogeneous photocatalysis using SrSnO3.

Etoposide is an antineoplastic agent used for treating lung cancer, testicular cancer, breast cancer, pediatric cancers, and lymphomas. It is a pollutant due to its mutagenic and carcinogenic potential. Disposal of waste from this drug is still insufficiently safe, and there is no appropriate waste treatment. Therefore, it is important to use advanced oxidative processes (AOPs) for the treatment and disposal of medicines like this. The use of strontium stannate (SrSnO3) as a catalyst in heterogeneous photocatalysis reactions has emerged as an alternative for the removal of organic pollutants. In our study, SrSnO3 was synthesized by the combustion method and characterized by X-ray diffraction (XRD), Raman, UV-Vis, and scanning electron microscopy (SEM) techniques, obtaining a surface area of 3.28 m2 g-1 with cubic and well-organized crystallinity and a band gap of 4.06 eV. The experimental conditions optimized for degradation of an etoposide solution (0.4 mg L-1) were pH 5 and catalyst concentration of 1 g L-1. The results showed that the degradation processes using SrSnO3 combined with H2O2 (0.338 mol L-1) obtained total organic carbon removal from the etoposide solution, 97.98% (± 4.03 × 10-3), compared with TiO2, which obtained a mineralization rate of 72.41% (± 6.95 × 10-3). After photodegradation, the degraded solution showed no toxicity to zebrafish embryos through embryotoxicity test (OECD, 236), and no genotoxicity using comet assay and micronucleus test.

Lanthanide-Organic Gels as a Multifunctional Supramolecular Smart Platform.

A multifunctional smart supramolecular platform based on a lanthanide-organic hydrogel is presented. This platform, which provides unique biocompatibility and tunable optical properties, is synthesized by a simple, fast, and reproducible eco-friendly microwave-assisted route. Photoluminescent properties enable the production of coated light-emitting diodes (LED), unique luminescent barcodes dependent on the excitation wavelength and thin-films for use in tamper seals. Moreover, piroxicam entrapped in hydrogel acts as a transdermal drug release device efficient in inhibiting edemas as compared to a commercial reference.

High photoluminescent metal-organic frameworks as optical markers for the identification of gunshot residues.

Gunshot residue (GSR) are solid particles produced when a firearm is discharged, and its detection is important evidence in forensic investigations. Currently, scanning electron microscopy coupled to energy dispersive spectroscopy (SEM-EDS) is the standard technique adopted for the analysis and identification of GSR; however, this methodology is inefficient for lead-free ammunition. Herein, we report the inclusion of high photoluminescent metal-organic frameworks in ammunition to allow for the visual detection of GSR. The tests indicated that marked GSR is easily visible in proportions above 5.0 wt %. A total of 1 g of marker suffices to tag 100 0.38 mm bullets or 62 0.40 mm bullets.