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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]

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 present work reports a newly developed square wave anodic stripping voltammetry (SWASV) methodology using novel gold nanostar–modified screen-printed carbon electrodes (AuNS/SPCE) and modified Britton-Robinson buffer (mBRB) for simultaneous detection of trace cadmium(II), arsenic(III), and selenium(IV). During individual and simultaneous detection, Cd2+, As3+, and Se4+ exhibited well-separated SWASV peaks at approximately − 0.48, − 0.09, and 0.65 V, respectively (versus Ag/AgCl reference electrode), which enabled a highly selective detection of the three analytes. Electrochemical impedance spectrum tests showed a significant decrease in charge transfer resistance with the AuNS/SPCE (0.8 kΩ) compared with bare SPCE (2.4 kΩ). Cyclic voltammetry experiments showed a significant increase in electroactive surface area with electrode modification. The low charge transfer resistance and high electroactive surface area contributed to the high sensitivity for Cd2+ (0.0767 μA (0.225 μg L−1)−1), As3+ (0.2213 μA (μg L−1)−1), and Se4+ (μA (μg L−1)−1). The three analytes had linear stripping responses over the concentration range of 0 to 100 μg L−1, with the obtained LoD for Cd2+, As3+, and Se4+ of 1.6, 0.8, and 1.6 μg L−1, respectively. In comparison with individual detection, the simultaneous detection of As3+ and Se4+ showed peak height reductions of 40.8% and 42.7%, respectively. This result was associated with the possible formation of electrochemically inactive arsenic triselenide (As2Se3) during the preconcentration step. Surface water analysis resulted in average percent recoveries of 109% for Cd2+, 93% for As3+, and 92% for Se4+, indicating the proposed method is accurate and reliable for the simultaneous detection of Cd2+, As3+, and Se4+ in real water samples. [ABSTRACT FROM AUTHOR]

One of the challenges preventing rapid, onsite voltammetric detection of arsenic(III) is the overlapping oxidation peak of copper(II). This paper describes a novel methodology for the voltammetric detection of trace levels of arsenic(III) in the presence of high copper(II) concentrations (up to the action level of 1.3 mg L−1 set by the US EPA for drinking water). Square wave stripping voltammetry tests were performed using disposable carbon screen printed electrodes modified with gold nanostars on samples buffered with Britton-Robinson buffer. The optimized parameters for accurate codetection of arsenic(III) and copper(II) were a buffer pH of 9.5, a loading of gold nanostars of 2.39 * 10 − 5 nmol per electrode, a deposition voltage of −0.8 V, and a deposition time of 180 s. Based on calibration testing, the limits of detection for arsenic(III) and copper(II) were determined to be 2.9 μg L−1 and 42.5 μg L−1, respectively. Furthermore, the linear ranges for arsenic and copper were 0–100 μg L−1 and 0–250 μg L−1 with sensitivities of 0.101 μA (μg L−1)−1 and 0.121 μA (μg L−1)−1, respectively. Interference testing was performed with several common ionic species, sodium bicarbonate, sodium chloride, tannic acid, iron(iii) chloride, magnesium chloride, calcium nitrate, and sodium sulfate, with only sodium bicarbonate significantly affecting the response. Validation testing in real-world samples was performed by comparison with graphite furnace atomic absorption spectroscopy. The validation testing demonstrated good accuracy and precision, expressed as percent recovery and relative standard deviation (RSD), respectively, in river water and tap water, with mean percent recoveries of 87.7% (RSD = 4.20%) and 83.2% (RSD = 10.02%), respectively. Image 1 • As(III) and Cu(II) were detected using gold nanostar modified CSPE. • Britton Robinson Buffer with pH 9.5 enabled codetection of As(III) and Cu(II). • 0–300 μg L−1 of As(III) was detected with Cu(II) concentrations up to 1.3 mg L−1. • An interference study showed minimal interference from common species. • Validation testing with GF-AAS showed significant potential for real-world use. [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]

Hydrogen is largely produced via natural gas reforming or electrochemical water-splitting, leaving organic solid feedstocks under-utilized. Plasma technology powered by renewable electricity can lead to the sustainable upcycling of plastic waste and production of green hydrogen. In this work, low-temperature atmospheric pressure plasma reactors based on transferred arc (transarc) and gliding arc (glidarc) discharges are designed, built, and characterized to produce hydrogen from low-density polyethylene (LDPE) as a model plastic waste. Experimental results show that hydrogen production rate and efficiency increase monotonically with increasing voltage level in both reactors, with the maximum hydrogen production of 0.33 and 0.42 mmol/g LDPE for transarc and glidarc reactors, respectively. For the transarc reactor, smaller electrode-feedstock spacing favors greater hydrogen production, whereas, for the glidarc reactor, greater hydrogen production is obtained at intermediate flow rates. The hydrogen production from LDPE is comparable despite the markedly different modes of operation between the two reactors. • Hydrogen production from polyethylene via atmospheric nonthermal plasma demonstrated. • Two plasma reactor designs with complementary characteristics experimentally evaluated. • Hydrogen production as function of operational parameters assessed. • Hydrogen production efficiency comparable despite different operation of the reactors. [ABSTRACT FROM AUTHOR]