Solar photothermo-catalysis is a fascinating multi-catalytic approach for volatile organic compounds (VOCs) removal. In this work, we have explored the performance and the chemico-physical features of non-critical, noble, metal-free MnO_x-ZrO₂ mixed oxides. The structural, morphological, and optical characterizations of these materials pointed to as a low amount of ZrO₂ favoured a good interaction and the ionic exchange between the Mn and the Zr ions. This favoured the redox properties of MnO_x increasing the mobility of its oxygens that can participate in the VOCs oxidation through a Mars-van Krevelen mechanism. The further application of solar irradiation sped up the oxidation reactions promoting the VOCs total oxidation to CO₂. The MnO_x-5 wt.%ZrO₂ sample showed, in the photothermo-catalytic tests, a toluene T₉₀ (temperature of 90% of conversion) of 180 °C and an ethanol T₉₀ conversion to CO₂ of 156 °C, 36 °C, and 205 °C lower compared to the thermocatalytic tests, respectively. Finally, the same sample exhibited 84% toluene conversion and the best selectivity to CO₂ in the ethanol removal after 5 h of solar irradiation at room temperature, a photoactivity similar to the most employed TiO₂-based materials. The as-synthetized mixed oxide is promising for an improved sustainability in both catalyst design and environmental applications.

Monitoring of ammonium ion levels in water is essential due to its significant impact on environmental and human health. This work aims to fabricate and characterize sensitive, real-time, low-cost, and portable amperometric sensors for low NH₄⁺ concentrations in water. Two strategies were conducted by cyclic voltammetry (CV): electrodeposition of Au nanoparticles on a commercial polyaniline/C electrode (Au/PANI/C), and CV of electropolymerized polyaniline on a commercial carbon electrode (Au/PANIep/C). Au NPs increase the electrical conductivity of PANI and its ability to transfer charges during electrochemical reactions. The electrode performances were tested in a concentration range from 0.35 µM to 7 µM in NH₄⁺ solution. The results show that the Au/PANI/C electrode performs well for high NH₄⁺ concentrations (0.34 µM LoD) and worsens for low NH₄⁺ concentrations (0.01 µM LoD). A reverse performance occurs for the electrode Au/PANIep/C, with a 0.03 µM LoD at low NH₄⁺ concentration and 0.07 µM LoD at high NH₄⁺ concentration. The electrodes exhibit a good reproducibility, with a maximum RSD of 3.68% for Au/PANI/C and 5.94% for Au/PANIep/C. In addition, the results of the repeatability tests show that the electrochemical reaction of sensing is fully reversible, leaving the electrode ready for a new detection event.

The progressive increase in nitrate’s (NO₃⁻) presence in surface and groundwater enhances environmental and human health risks. The aim of this work is the fabrication and characterization of sensitive, real-time, low-cost, and portable amperometric sensors for low NO₃⁻ concentration detection in water. Copper (Cu) micro-flowers were electrodeposited on top of carbon screen-printed electrodes (SPCEs) via cyclic voltammetry (with voltage ranging from −1.0 V to 0.0 V at a scan rate of 0.1 V s⁻¹). The obtained sensors exhibited a high catalytic activity toward the electro-reduction in NO₃⁻, with a sensitivity of 44.71 μA/mM. They had a limit of detection of 0.87 µM and a good dynamic linear concentration range from 0.05 to 3 mM. The results were compared to spectrophotometric analysis. In addition, the devices exhibited good stability and a maximum standard deviation (RSD) of 5% after ten measurements; reproducibility, with a maximum RSD of 4%; and repeatability after 10 measurements with the RSD at only 5.63%.

The detection of Legionella in environmental samples, such as water, is crucial for public health monitoring and outbreak prevention. Although effective, traditional detection methods, including culture-based techniques and polymerase chain reaction, have limitations such as long processing times, trained operators, and the need for specialized laboratory equipment. Biosensing technologies offer a promising alternative due to their rapid, sensitive, cost-effectiveness, and on-site detection capabilities. To summarize the current advancements in biosensor development for detecting Legionella in environmental samples, we used ‘Legionella’ AND ‘biosensors’ NEAR ‘environmental samples’ OR ‘water’ as keywords searching through the most relevant biomedical databases for research articles. After removing duplicates and inadequate articles from the n.1268 records identified using the PRISMA methodology exclusion criteria, we selected n.65 full-text articles which suited the inclusion criteria. Different results between the studies describing the current biosensing techniques, including optical, electrochemical, magnetic, and mass-sensitive sensors were observed. For each biosensing technique, sensitivity, specificity, and detection limits were evaluated. Furthermore, the integration of nanomaterials, microfluidics, and portable devices in biosensor systems’ design were discussed, highlighting their role in enhancing detection performance. The potential challenges and future directions in the field of Legionella biosensing were also addressed, providing insights into the feasibility of implementing these technologies in routine environmental monitoring. Undoubtedly, biosensors can play a crucial role in the early detection and management of Legionella infections and outbreaks, ultimately protecting public health and safety.

We present the design, fabrication, and testing of a low-cost, miniaturized detection system that utilizes chemiluminescence to measure the presence of adenosine triphosphate (ATP), the energy unit in biological systems, in water samples. The ATP–luciferin chemiluminescent solution was faced to a silicon photomultiplier (SiPM) for highly sensitive real-time detection. This system can detect ATP concentrations as low as 0.2 nM, with a sensitivity of 79.5 A/M. Additionally, it offers rapid response times and can measure the characteristic time required for reactant diffusion and mixing within the reaction volume, determined to be 0.3 ± 0.1 s. This corresponds to a diffusion velocity of approximately 44 ± 14 mm²/s.

In this work, sulfonated pentablock copolymer (s-PBC) and s-PBC mixed with graphene oxide (s-PBC_GO) layers were deposited on polypropylene (PP) fibrous filters and tested as active coatings for the removal of cobalt ions from water using adsorption and filtration processes. Some of the coated filters were treated by UV light irradiation to modify their hydrophilic properties. The filters were characterized, before and after the processes, by energy-dispersive X-ray (EDX) analysis and Fourier transform infrared spectroscopy (FT-IR). The Q_t (mg/g) values, defined as the weight ratio between the removed ions and the coating layer, were evaluated. In the case of adsorption processes, the best results for the removal of Co²⁺ ions were achieved by the s-PBC_GO coating, with a Q_t of 37 mg/g compared to 21 mg/g obtained by the s-PBC. This was ascribed to the presence of GO, which contains more favorable sites able to adsorb positive ions from the solution. Vice versa, for filtration processes, the s-PBC coated filters show similar or slightly better results than the s-PBC_GO coated ones. Such differences can be ascribed to the shorter contact time between the solution and the coating layer in the case of filtration, with respect to adsorption processes, thus reducing the chance for the ions to be adsorbed on the GO layers before passing through the filter. A collateral effect, observed in this study and enhanced in the case of UV-treated coatings, is the release of radical oxysulfur species. The mechanisms involved in this effect are discussed and identified as a consequence of the interaction between the coating layers and metal ions. In order to identify the mechanism of oxysulfur radicals formation and considering a water sample closer to real water, the Co²⁺ ions adsorption experiments were conducted in the presence of a competitive organic contaminant (i.e., methyl orange, MO).