Striking the balance: unveiling the interplay between photocatalytic efficiency and toxicity of La-incorporated Ag3PO4.

Persistent molecules, such as pesticides, herbicides, and pharmaceuticals, pose significant threats to both the environment and human health. Advancements in developing efficient photocatalysts for degrading these substances can play a fundamental role in remediating contaminated environments, thereby enhancing safety for all forms of life. This study investigates the enhancement of photocatalytic efficiency achieved by incorporating La3+ into Ag3PO4, using the co-precipitation method in an aqueous medium. These materials were utilized in the photocatalytic degradation of Rhodamine B (RhB) and Ciprofloxacin (CIP) under visible light irradiation, with monitoring conducted through high-performance liquid chromatography (HPLC). The synthesized materials exhibited improved stability and photodegradation levels for RhB. Particularly noteworthy was the 2% La3+-incorporated sample (APL2), which achieved a 32.6% mineralization of CIP, nearly three times higher than pure Ag3PO4. Toxicological analysis of the residue from CIP photodegradation using the microalga Raphidocelis subcapitata revealed high toxicity due to the leaching of Ag+ ions from the catalyst. This underscores the necessity for cautious wastewater disposal after using the photocatalyst. The toxicity of the APL2 photocatalysts was thoroughly assessed through comprehensive toxicological tests involving embryo development in Danio rerio, revealing its potential to induce death and malformations in zebrafish embryos, even at low concentrations. This emphasizes the importance of meticulous management. Essentially, this study adeptly delineated a thorough toxicological profile intricately intertwined with the photocatalytic efficacy of newly developed catalysts and the resultant waste produced, prompting deliberations on the disposal of degraded materials post-exposure to photocatalysts.

Pyrazinamide photodegradation on NiWO4-palygorskite nanocomposites under polychromatic irradiation.

In this work, antibiotic pyrazinamide (PZA) photodegradation on palygorskite (Pal), NiWO4 crystals, and NiWO4-Pal (2, 6, and 10%) nanocomposites was evaluated under polychromatic irradiation. In the characterization of the samples, XRD patterns displayed good crystallinity for NiWO4 crystals and nanocomposites. In addition, the diffractograms were used in the Rietveld refinement for phase indexing, revealing a wolframite-type monoclinic structure with the space group P2/c. The active vibrational modes related to the characteristic groups of the samples were identified using Raman and FTIR spectroscopy. Photoluminescence (PL) spectra revealed that NiWO4 and NiWO4-Pal (2%) nanocomposite have the highest electron-hole pair recombination rate, and the contribution of the green component in the NiWO4-Pal (2%) nanocomposite indicates a greater contribution of deep energy levels to the PL profile. DRS in the UV-visible region indicated that NiWO4 crystals have indirect band-gap energy (Egap) 2.64 eV; NiWO4-Pal (2, 6, and 10%) nanocomposites have 2.62, 2.58, and 2.59 eV, respectively; and Pal has 2.83 eV. The catalytic tests showed that the NiWO4-Pal (2%) nanocomposite samples, under polychromatic radiation, exhibit greater efficiency in photodegradation at 110 min, with yield of 98.5%. The ROS tests indicated that the studied reactive species play a similar role in PZA photodegradation.

Polypropylene Modified with Ag-Based Semiconductors as a Potential Material against SARS-CoV-2 and Other Pathogens.

The worldwide outbreak of the coronavirus pandemic (COVID-19) and other emerging infections are difficult and sometimes impossible to treat, making them one of the major public health problems of our time. It is noteworthy that Ag-based semiconductors can help orchestrate several strategies to fight this serious societal issue. In this work, we present the synthesis of α-Ag2WO4, ß-Ag2MoO4, and Ag2CrO4 and their immobilization in polypropylene in the amounts of 0.5, 1.0, and 3.0 wt %, respectively. The antimicrobial activity of the composites was investigated against the Gram-negative bacterium Escherichia coli, the Gram-positive bacterium Staphylococcus aureus, and the fungus Candida albicans. The best antimicrobial efficiency was achieved by the composite with α-Ag2WO4, which completely eliminated the microorganisms in up to 4 h of exposure. The composites were also tested for the inhibition of SARS-CoV-2 virus, showing antiviral efficiency higher than 98% in just 10 min. Additionally, we evaluated the stability of the antimicrobial activity, resulting in constant inhibition, even after material aging. The antimicrobial activity of the compounds was attributed to the production of reactive oxygen species by the semiconductors, which can induce high local oxidative stress, causing the death of these microorganisms.

Bioactive Ag3PO4/Polypropylene Composites for Inactivation of SARS-CoV-2 and Other Important Public Health Pathogens.

The current unprecedented coronavirus pandemic (COVID-19) is increasingly demanding advanced materials and new technologies to protect us and inactivate SARS-CoV-2. In this research work, we report the manufacture of Ag3PO4 (AP)/polypropylene (PP) composites using a simple method and also reveal their long-term anti-SARS-CoV-2 activity. This composite shows superior antibacterial (against Staphylococcus aureus and Escherichia coli) and antifungal activity (against Candida albicans), thus having potential for a variety of technological applications. The as-manufactured materials were characterized by XRD, Raman spectroscopy, FTIR spectroscopy, AFM, UV-vis spectroscopy, rheology, SEM, and contact angle to confirm their structural integrity. Based on the results of first-principles calculations at the density functional level, a plausible reaction mechanism for the initial events associated with the generation of both hydroxyl radical •OH and superoxide radical anion •O2- in the most reactive (110) surface of AP was proposed. AP/PP composites proved to be an attractive avenue to provide human beings with a broad spectrum of biocide activity.