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Pesticides are primarily used in agriculture to protect crops and extend their longevity. However, pesticide exposure has been linked to various acute and chronic health effects, raising significant environmental concerns. Current detection methods are often expensive and time-consuming, relying on complex instruments. Although enzyme-inhibition-based microfluidic paper-based analytical device (mPAD) platforms offer an easier alternative, they suffer from slow analyte transport and analyte adsorption issues in microchannels. Consequently, there is a need for a fast, simple, and cost-effective point-of-need platform for pesticide sensing. In this study, we present a rapid microfluidic platform for on-site pesticide residue detection. Unlike traditional mPAD platforms, our system transports pesticide samples through hollow capillary channels within seconds without adsorption of pesticides in the microchannels. While much research has focused on acetylcholinesterase inhibition on paper, this study is the first to introduce a tyrosinase inhibition-based assay on a paper platform for pesticide detection. Ziram, a representative dithiocarbamate pesticide, was detected using a colorimetric enzymatic inhibition assay. A limit of detection (LoD) of 1.5 ppm was obtained. In this study, we optimized the fast-flow device, assessed its stability and susceptibility to various interferences, and conducted real-sample tests using glove extraction to evaluate its capability in real-world settings. Spike recovery analysis revealed an extraction efficiency of 82.5% to 87.5% for leather gloves and 68.9% to 71.9% for nitrile gloves. This platform demonstrates strong selectivity against interferences, with the enzyme retaining 90% activity even after a week under the established storage protocols with room for further investigation. While primarily a proof of concept, this device shows promise as an additional tool for pesticide detection, with potential future integration into multiplexed devices. [ABSTRACT FROM AUTHOR]

Timely, efficient on-site detection of pesticides such as methyl parathion (MP) is crucial to ensure public health. This study introduces the first disposable electrochemically reduced graphene oxide (ErGO) modified electrode for rapid MP detection. A square wave anodic stripping voltammetry method for the detection of MP was developed using these ErGO-modified carbon screen-printed electrodes. Based on this study, graphene's high electric conductivity and unique structure enhanced the sensitivity of the electrode for MP detection. Following optimization of the pH, equilibrium period, deposition potential, and period, the methodology demonstrated high sensitivity and reproducibility. Using the enhanced experiment conditions, calibration experiments were performed with a concentration range of 0 to 150 µg L-1 of MP. A consistent oxidation peak was observed at -0.180 V. The calibration data showed the increase in the peak height was linearly correlated to the increase in MP concentration, with a correlation coefficient of 0.9854. The sensitivity of the developed methodology was 0.0887 µA (µg L-1)-1, and the limit of detection was 9.06 µg L-1. The methodology was successfully applied to multiple water samples, specifically river water, groundwater, and General Test Water, with recovery rates of 106.01% (standard deviation = 1.46%), 109.51% (standard deviation=0.44%), and 97.69% (standard deviation=1.49%), respectively. [ABSTRACT FROM AUTHOR]

CuBiW2O8 (CBTO), with a band gap of 1.9–2.0 eV, responds to a wide region of the electromagnetic spectrum, which makes it a good candidate for solar-driven photocatalytic energy conversion and water treatment. We have previously demonstrated a Cu-rich solid state approach that enables the synthesis of CBTO accompanied by thermodynamically stable Bi2WO6 impurity. Here, we describe an improved synthesis protocol with decreased impurity and synthesis time, and the first demonstration of CBTO as a functional material using photocatalytic Cr(VI) photoreduction as a probe reaction. Transient absorption spectroscopy (TAS) was performed to investigate the ultrafast dynamics of the charge carriers after photoexcitation. The presence of two populations of photoexcited carriers was found, including short-lived free carriers with ∼10 ps lifetime and long-lived shallowly-trapped carriers with ∼1 ns lifetime. Together with carrier mobilities measured in our previous study, the new TAS results indicate that the long-lived charges have diffusion lengths similar to the CBTO particle size and were likely responsible for the majority of the photocatalytic activity. High activity of CBTO for Cr(VI) photoreduction (∼100% reduction of 5 mg L−1 of Cr(VI) in 15 minutes) was demonstrated, which clearly establishes the promise of this novel oxide for visible light-driven photocatalytic applications. Radical quenching experiments indicate that both ˙OH radicals and O2˙− radicals are produced by CBTO and are involved in the photoreduction of Cr(VI). Repeated photocatalysis tests and analysis of the surface after the reaction show that CBTO is a stable and potentially reusable catalyst. Insights gained from correlating the synthesis conditions, carrier dynamics, and reactive species suggests that CBTO prepared with the improved protocol would be a favorable choice for photocatalytic reactions such as water decontamination from organic pollutants, water splitting, and solar fuel generation using visible light. [ABSTRACT FROM AUTHOR]

The production of hydrogen from plastic and biomass waste via processes powered by renewable electricity can be a pivotal contributor to an effective waste management system in a circular economy. Copyrolysis of plastic and biomass waste mixtures can be economically appealing, not only by eliminating the need for waste stream separation but also by potentially synergizing hydrogen production. In this study, we present evidence of such hydrogen production synergy in plasma copyrolysis of mixtures of low-density polyethylene (LDPE) and cellulose (CE) as plastic and biomass waste models, respectively. We treated samples made of mixtures of LDPE and CE powders at five different mass ratios, ranging from 100% LDPE to 100% CE. We used non-thermal nitrogen plasma and argon plasma in a Streamer Dielectric-Barrier Discharge (SDBD) configuration under atmospheric pressure conditions. Synergistic hydrogen production was observed when nitrogen was used as the working gas, but not with argon, resulting in up to 37% greater hydrogen production compared to non-synergistic expectations. This outcome is attributed to the nitrogen-doped oxygenated carbonaceous residues from CE pyrolysis catalyzing the dehydrogenation and reforming of light alkanes resulting from the decomposition of LDPE. [Display omitted] • Plasma copyrolysis of LDPE and cellulose using nitrogen leads to increased hydrogen yield. • Synergy leads to up to 37% increased hydrogen production. • The lowest energy cost of 1.5 MWh/kg-H 2 is achieved for 1:2 LDPE:cellulose mass ratio. • Synergy attributed to nitrogen doping of cellulose-derived carbonaceous residues. [ABSTRACT FROM AUTHOR]

The valorization of waste, by creating economic value while limiting environmental impact, can have an essential role in sustainable development. Particularly, polymeric waste such as biomass and plastics can be used for the production of green hydrogen as a carbon-free energy carrier through the use of nonthermal plasma powered by renewable, potentially surplus, electricity. In this study, a Streamer Dielectric-Barrier Discharge (SDBD) reactor is designed and built to extract hydrogen and carbon co-products from cellulose and low-density polyethylene (LDPE) as model feedstocks for biomass and plastic waste, respectively. Spectroscopic and electrical diagnostics, together with modeling, are used to estimate representative plasma properties, namely electron and excitation temperatures, number density, and power consumption. Cellulose and LDPE are plasma-treated for different treatment times to characterize the evolution of the hydrogen production process. Gas products are analyzed using gas chromatography to determine the mean hydrogen production rate, production efficiency, hydrogen yield, selectivity, and energy cost. The results show that the maximum hydrogen production efficiency for cellulose is 0.8 mol/kWh, which is approximately double that for LDPE. Furthermore, the energy cost of hydrogen production from cellulose is 600 kWh/kg of H 2 , half that of LDPE. Solid products are examined via scanning electron microscopy, revealing the distinct morphological structure of the two feedstocks treated, as well as by elemental composition analysis. The results demonstrate that SDBD plasma is effective at producing hydrogen from cellulose and LDPE at near atmospheric pressure and relatively low-temperature conditions in rapid-response and compact processes. [Display omitted] • Streamer Dielectric Barrier Discharge (SDBD) reactor for hydrogen production from polymeric solids. • Treatment of cellulose and LDPE as biomass and plastic waste models for different treatment times. • Quantification and characterization of gas and solid products. • Minimum energy cost of 600 kWh/kg of H 2 for cellulose, half of that for LDPE. [ABSTRACT FROM AUTHOR]

Heavy metal contamination is an increasing global threat to human and environmental health, particularly in resource-limited areas. Traditional platforms for heavy metal detection are labor intensive and expensive and require lab facilities. While paper-based colorimetric sensors offer a simpler approach, their sensitivity limitations prevent them from meeting legislative requirements for many metals. Existing preconcentration systems, on the other hand, can achieve lower detection limits but typically focus on analyzing only one metal, making comprehensive monitoring difficult. We address these limitations by introducing a low-cost preconcentration system coupled with colorimetric analysis for the simultaneous detection of seven metal ions at low ppb levels without the need for external equipment outside a smartphone. The system achieved detection limits of 15 ppb (Ni(II)), 7 ppb (Cu(II)), 2 ppb (Fe(III)), 20 ppb (Cr(VI)), 13 ppb (Pb(II)), 26 ppb (Hg(II)), and 15 ppb (Mn(II)) with six out of seven limits of detection values falling well below EPA regulatory guidelines for drinking water. The user-friendly Fill, Fold, Photo approach eliminates complex pretreatment steps. Smartphone-based detection offers portable quantification within seconds. Employing masking strategies ensured higher selectivity for each assay on the card, while our packaging protocols enable system stability for over 4 weeks of study, facilitating mass production and deployment within a realistic time frame. To validate the sensor's performance in real-world scenarios, the sensor was tested with environmental water samples. The sensor demonstrated good recovery, ranging from 77% to 94% compared to the standard ICP-MS method. Furthermore, spike recovery analysis confirmed the sensor's accuracy, with a relative standard deviation (RSD) of less than 15%. This technology holds significant promise for future development as a convenient, portable solution for field-based monitoring of a broad spectrum of water contaminants, including pesticides, PFAS, fertilizers, and beyond.