Photocatalytic Degradation of Paracetamol under Simulated Sunlight by Four TiO2 Commercial Powders: An Insight into the Performance of Two Sub-Micrometric Anatase and Rutile Powders and a Nanometric Brookite Powder

The photocatalytic degradation of the emerging contaminant paracetamol in aqueous solution has been studied under 1 SUN (~1000 W m−2) in the presence of four commercial TiO2 powders, namely sub-micrometric anatase and rutile, and nanometric brookite and P25 (the popular anatase/rutile mixture used as a benchmark in most papers). The rutile powder showed low activity, whereas, interestingly, the anatase and the brookite powders outperformed P25 in terms of total paracetamol conversion to carboxylic acids, which, according to the literature, are the final products of its degradation. To explain such results, the physicochemical properties of the powders were studied by applying a multi-technique approach. Among the physicochemical properties usually affecting the photocatalytic performance of TiO2, the presence of some surface impurities likely deriving from K3PO4 (used as crystallization agent) was found to significantly affect the percentage of paracetamol degradation obtained with the sub-micrometric anatase powder. To confirm the role of phosphate, a sample of anatase, obtained by a lab synthesis procedure and having a "clean” surface, was used as a control, though characterized by nanometric particles and higher surface area. The sample was less active than the commercial anatase, but it was more active after impregnation with K3PO4. Conversely, the presence of Cl at the surface of the rutile did not sizably affect the (overall poor) photocatalytic activity of the powder. The remarkable photocatalytic activity of the brookite nanometric powder was ascribed to a combination of several physicochemical properties, including its band structure and nanoparticles size.

Virus removal from aqueous environments with polyelectrolyte coatings on a polypropylene fleece

The adsorption of viruses from aqueous solution is frequently performed to detect viruses. Charged filtration materials capture viruses via electrostatic interactions, but lack the specificity of biological virus‐binding substances like heparin. Herein, we present three methods to immobilize heparin‐mimicking, virus‐binding polymers to a filter material. Two mussel‐inspired approaches are used, based on dopamine or mussel‐inspired dendritic polyglycerol, and post‐functionalized with a block‐copolymer consisting of linear polyglycerol sulfate and amino groups as anchor (lPGS‐b‐NH2). As third method, a polymer coating based on lPGS with benzophenone anchor groups is tested (lPGS‐b‐BPh). All three methods yield dense and stable coatings. A positively charged dye serves as a tool to quantitatively analyze the sulfate content on coated fleece. Especially lPGS‐b‐BPh is shown to be a dense polymer brush coating with about 0.1 polymer chains per nm2. Proteins adsorb to the lPGS coated materials depending on their charge, as shown for lysozyme and human serum albumin. Finally, herpes simplex virus type 1 (HSV‐1) and severe acute respiratory syndrome coronavirus type 2 (SARS‐CoV‐2) can be removed from solution upon incubation with coated fleece materials by about 90% and 45%, respectively. In summary, the presented techniques may be a useful tool to collect viruses from aqueous environments.

Removal of ivermectin from aqueous media using commercial, bentonite-based organophilic clay as an adsorbent

The worldwide use of pharmaceuticals is of concern to those researchers who develop new techniques for the removal of these compounds from the aquatic medium. The objective of the present work was to characterize and evaluate the performance of a commercial, bentonite-based organophilic clay in removing ivermectin from aqueous solution. The adsorbent was characterized by nitrogen physisorption, thermogravimetric-differential scanning calorimetry (TG-DSC), X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR). Batch-scale adsorption experiments were performed to evaluate the kinetics, isotherms, thermodynamics and effect of pH on removal of this drug and reuse of the clay. The bentonite has a small specific surface area with an irregular surface. The Elovich kinetic model fits the experimental data better than other models, indicating that chemisorption contributes to drug removal in this case. The Langmuir and Sips isothermal models best fit the experimental equilibrium data. The process was shown to be favorable (ΔG°ads<0), endothermic (ΔH°ads>0), with an increase in the degrees of freedom at the solid–liquid interface (ΔS°ads>0), and with characteristics of a physical-chemical adsorption process (Ea = 11.065 kJ mol–1) under the study conditions. Adsorption was favored at the natural pH of the solution and the organophilic clay could be regenerated with water and reused in consecutive adsorption cycles. The amount of ivermectin adsorbed on the organophilic clay ranged from 1.78 to 3.88 mg g–1. The organophilic clay was shown to be a cost-effective potential adsorbent for ivermectin-contaminated water-treatment applications.

Significant Fragmentation of Disposable Surgical Masks—Enormous Source for Problematic Micro/Nanoplastics Pollution in the Environment

The pandemic of COVID-19 disease has brought many challenges in the field of personal protective equipment. The amount of disposable surgical masks (DSMs) consumed increased dramatically, and much of it was improperly disposed of, i.e., it entered the environment. For this reason, it is crucial to accurately analyze the waste and identify all the hazards it poses. Therefore, in the present work, a DSM was disassembled, and gravimetric analysis of representative DSM waste was performed, along with detailed infrared spectroscopy of the individual parts and in-depth analysis of the waste. Due to the potential water contamination by micro/nanoplastics and also by other harmful components of DSMs generated during the leaching and photodegradation process, the xenon test and toxicity characteristic leaching procedure were used to analyze and evaluate the leaching of micro/nanoplastics. Micro/nanoplastic particles were leached from all five components of the mask in an aqueous medium. Exposed to natural conditions, a DSM loses up to 30% of its mass in just 1 month, while micro/nanoplastic particles are formed by the process of photodegradation. Improperly treated DSMs pose a potential hazardous risk to the environment due to the release of micro/nanoparticles and chloride ion content.

Determination of Ascorbic Acid in Pharmaceuticals and Food Supplements with the New Potassium Ferrocyanide-Doped Polypyrrole-Modified Platinum Electrode Sensor

This paper reports the results obtained from the determination of ascorbic acid with platinum-based voltammetric sensors modified with potassium hexacyanoferrate-doped polypyrrole. The preparation of the modified electrodes was carried out by electrochemical polymerization of pyrrole from aqueous solutions, using chronoamperometry. Polypyrrole films were deposited on the surface of the platinum electrode, by applying a constant potential of 0.8 V for 30 s. The thickness of the polymer film was calculated from the chronoamperometric data, and the value was 0.163 μm. Cyclic voltammetry was the method used for the Pt/PPy-FeCN electrode electrochemical characterization in several types of solution, including KCl, potassium ferrocyanide, and ascorbic acid. The thin doped polymer layer showed excellent sensitivity for ascorbic acid detection. From the voltammetric studies carried out in solutions of different concentrations of ascorbic acid, ranging from 1 to 100 × 10−6 M, a detection limit of 2.5 × 10−7 M was obtained. Validation of the analyses was performed using pharmaceutical products with different concentrations of ascorbic acid, from different manufacturers and presented in various pharmaceutical forms, i.e., intravascular administration ampoules, chewable tablets, and powder for oral suspension.

Electrolysis Study Effect on Electrolyzed Water as Disinfectant and Sanitizer

The use of harmful alcohol-based disinfectants and sanitizers was a major concern throughout the CoVID-19 era. Frequent use of alcohol-based sanitizer can dry up the skin, and the effect is worsening for individuals with sensitive skin. Alcohol-based disinfectants are flammable and can ignite if used near a flame, spark, or other source of ignition. Using the electrolysis of sodium chloride (NaCl) aqueous solution method, this study aims to make Hypochlorous Acid (HOCl), a safe disinfectant and sanitizer. Two critical parameters were tested on the electrolysis effect of producing HOCl. The first is the amount of sodium chloride (NaCl) present, while the second is the type of electrode used, which are carbon, graphite, and titanium. The results showed that 10 grams of NaCl produces 50-200 ppm of HOCl, which is good for sanitizing purposes, and 30 grams of NaCl produces 500-800 ppm of HOCl, which is good for disinfecting purposes. The graphite electrode was also demonstrated to be capable of producing a clean HOCl solution. Using a UV-vis spectrophotometer, the effectiveness of the HOCl produced was determined, and it was discovered that HOCl is capable of killing bacteria. As a result, HOCl can be applied as a safe disinfectant and sanitizer in the fight against COVID-19.

Human coronavirus inactivation by atmospheric pressure helium plasma

The recent global pandemic of Corona Virus Disease-19 has impacted all aspects of society, producing a growing demand for a powerful virus inactivation method. To assess a potential and mechanism of human coronavirus inactivation using atmospheric pressure plasma (APP) technology, replication of a human coronavirus (HCoV-229E) after He + H2O APP plume exposure was evaluated using rhesus monkey kidney epithelial cells. The HCoV-229E titers were reduced by 3 log(10)TCID(50) after the APP exposure for 30 s, showing a strong virus-inactivation efficacy of the APP. It was experimentally verified that the APP produced the liquid-phase reactive oxygen and nitrogen species (RONS) at high rates [e.g. (OH)-O-center dot: similar to 1.7 nmol s(-1), H2O2 (including H2O2 precursors): similar to 9.2 nmol s(-1), NO2 (-) (including NO2 (-) precursors): similar to 3.3 nmol s(-1)]. However, an administration of H2O2 with NO2 (-) failed to inactivate the virus and only Mn type superoxide dismutase among several RONS scavengers for (OH)-O-center dot, HO2 (center dot)/O-2 O-center dot-, 1(2), and (NO)-N-center dot/(NO2)-N-center dot was significantly effective for the recovery of the APP-induced decrease in the viral titers. This suggests O-2 (center dot-)-related chemical reaction in a network of interconnected reactions induced by the APP exposure is very important for the APP-induced virus inactivation. These results provide new insight into a more efficient inactivation method of human coronavirus using APPs.

Simulating Electronic Absorption Spectra of Atmospherically Relevant Molecules: A Systematic Assignment for Enhancing Undergraduate STEM Education

Computational and atmospheric chemistry are two important branches of contemporary chemistry. With the present topical nature of climate change and global warming, it is more crucial than ever that students are aware of and exposed to atmospheric chemistry, with an emphasis on how modeling may aid in understanding how atmospherically relevant chemical compounds interact with incoming solar radiation. Nonetheless, computational and atmospheric chemistry are under-represented in most undergraduate chemistry curricula. In this manuscript, we describe a simple and efficient method for simulating the electronic absorption spectral profiles of atmospherically relevant molecules that may be utilized in an undergraduate computer laboratory. The laboratory results give students hands-on experience in computational and atmospheric chemistry, as well as electronic absorption spectroscopy.