Contaminated Water Samples Research Articles

Cadmium oxide/calcium ferrite nanocomposite-based enhanced electrochemical sensing of metronidazole

The current study aimed to synthesize a cadmium oxide/calcium ferrite nanocomposite (CdO/CaFe2O4–NC) by sol–gel auto-combustion method, then applied on the surface of a glassy carbon electrode to fabricate a (CdO/CaFe2O4–NC/GCE) as a sensor for the electrochemical detection of metronidazole (MNZ). The characterization of synthesized CaFe2O4-NPs and CdO/CaFe2O4–NC was carried out through various analytical techniques, to confirm surface morphology, crystallite nature, average particle size, magnetic behavior, and stability. It is an effective electrochemical method for the detection of MNZ. The fabricated electrode was characterized by cyclic voltammetry, indicating its diffusion-controlled electron transfer behavior. Thus, CdO/CaFe2O4–NC/GCE was used to quantify MNZ using differential pulse voltammetry with a dynamic range of 0.05–130 µM (R2 = 0.0996) and LOD of 0.034 µM. The electrochemical method showed significant stability, sensitivity, and reproducibility (RSD < 4.00 %). The fabricated sensor was successfully applied to the contaminated water samples with quantitative recoveries up to 93.02 % by the spiking method.

Predicting the spread of contamination in water distribution networks laid on sloping terrains

Contamination in domestic and drinking water during the conveyance process is one of the biggest health risks of all time. This is a very common hazard that is expected in the areas where water, sewer, and drainage pipes are laid in trenches near each other. The extent of the contamination spread in the case of intrusion through a pipe leak for water distribution networks (WDNs) laid on sloping terrain is not known. This article deals with the simulation and hydraulic analysis of organic contaminant intrusion in WDNs with significant consideration of the slope of the laid pipes. The source of organic contamination is considered to be the nearby leaking sewer water. The effects of sloping terrain on contaminant spread in the pipe network are studied in detail by injecting contaminant concentrations at eight different critical locations in the network. The results of contamination spread after a particular time at all nodes are compiled, and by using statistical techniques, a relation between the contaminant spread and pipe slope is proposed. The presented model is validated by comparing the actual values of the contaminant in water samples obtained at the site with the calculated ones, and it shows that the values deviate within the range of ±2% only, which is considered a good match. The research proves to be beneficial for the management of water distribution through pipe networks against contaminants to maintaining water quality and public health.

Advanced Electrochemical Detection of 2,4-dichlorophenol in Water with Molecularly Imprinted Chitosan Stabilized Gold Nanoparticles

2,4-Dichlorophenol (2,4-DCP) is a hazardous chemical that can be passed down to offspring. Because 2,4-DCP degrades slowly and can be passed down to future generations, it’s a pesticide that needs to be continuously monitored and managed. With the use of chitosan-stabilized AuNPs on a glassy carbon electrode and the molecular imprinting technique, an effective electrochemical sensor has been built for the selective determination of 2,4-DCP in different aqueous samples. The analyte’s electroactive surface area and number of interaction sites are both increased by the AuNPs. The formulated AuNPs were characterized using several material characterization techniques. Molecularly imprinted nanomaterials provided the selectivity against other interfering chlorophenols. With a detection limit of 6.33 nM and a broad linear dynamic range of 21.09 to 310 nM, 2,4-DCP was found using differential pulse voltammetry. Without interference from structural analogs, the sensor was effectively evaluated in a variety of contaminated water samples.

Removal of contaminants from river Jakara using iron oxide nano particles prepared from Citrullus lanatus fruit waste

Achieving sustainable development requires efficient waste water treatment. Green synthesized iron nanoparticles have attracted much attention as potential catalysts for water remediation in view of their lost cost, high reactivity and good adsorption capacity. This study investigated the applicability of iron oxide nanoparticles synthesized from Citrullus lanatus fruit waste (IONP) in the remediation of contaminated water samples that were collected from River Jakara in Kano State Nigeria. The prepared nanoparticle was characterized using Brunauer–Emmett–Teller (BET) surface area, Scanning Electron Microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy and Thermogravimetric Analysis (TGA). The BET results revealed that IONP have large surface area and are nanometer sized particles. SEM analysis indicated that the adsorbent contain microsphere which might have facilitated the efficient purification of the river water while TGA study revealed that the adsorbent exhibited a three step decomposition process. Data obtained from XRD indicated that the synthesized adsorbent is of high purity and crystalline in nature with an average particle size of 17 nm. Results obtained after treatment of the river water with the adsorbent gave enhanced values of Total Dissolved Solids, Turbidity, Chemical Oxygen Demand, Dissolved Oxygen, phosphate and pH; thus confirming the high adsorption ability of the prepared nanoparticles. The percentage removal of Ni(II) Pb (II) and Cd (II) ions in the river water by IONP was found to depend on adsorbent concentration, agitation time and pH. The adsorption process of these metal ions onto the adsorbent was best described by the Langmuir isotherm model and followed pseudo second order kinetics. The regeneration stability of the adsorbent was adequate when treated with the heavy metals ions at optimum conditions. The nanoparticle synthesized from Citrullus lanatus waste was found to be an efficient and environmentally friendly alternative for treatment of contaminated water.

Enhancement of solar water disinfection using different types of clay

This study delves into the impact of incorporating natural nanoparticles (mineral clays) into contaminated water during the Solar water disinfection (SODIS) process. The experiment involved introducing contaminated water samples into glass containers containing 1 × 10−3 gm/ml of a specific clay type. These containers were then exposed to solar radiation for varying time intervals. Subsequently, samples were extracted from each container, and the total counts of Total Coliform, P. aeruginosa aeruginosa, and E.coli were measured using the IDEXX setup. The results revealed that Zeolite, a specific type of clay, exhibited the shortest disinfection process among the mineral clay samples. The optimal concentration of Zeolite, which effectively reduced the concentration of Total Coliform, P. aeruginosa, and E.coli concentration, was 1 × 10−3 gm/ml. In conclusion, adding Zeolite to wastewater was observed to positively impact the disinfection process, accelerating the inactivation process by reducing the number of pathogenic microorganisms.

Liquid crystal immunosensors for the selective detection of Escherichia coli with a fast analysis tool

The consumption of contaminated food may cause serious illnesses, and traditional methods to detect Escherichia coli are still associated with long waiting times and high costs given the necessity to transport samples to specialized laboratories. There is a need to develop new technologies that allow cheap, fast, and direct monitoring at the site of interest. Thus, in this work, we developed optical immunosensors for the selective detection of E. coli, based on liquid crystal technology, whose molecules can align in different manners depending on the boundary conditions (such as substrates) as well as the environment that they experience. Each glass substrate was functionalized with anti-E. coli antibody using cysteamine as an intermediate, and a vertical alignment was imposed on the liquid crystal molecules by using DMOAP during functionalization. The presence of bacteria disrupts the alignment of the liquid crystal molecules, changing the intensity of light emerging between cross polarizers, measured using a polarized optical microscope and a monochromator. It was possible to detect E. coli in suspensions in the concentration range from 2.8 cells/mL to 2.8×109 cells/mL. Selectivity was also evaluated, and the sensors were used to analyze contaminated water samples. A prototype was developed to allow faster, in-situ, and easier analysis avoiding bulky instruments.

Evaluation of Bioadsorption Efficiency of the Spent Mushroom Substrate of Calocybe indica for removing Iron from some contaminated Water Samples

Evaluation of Bioadsorption Efficiency of the Spent Mushroom Substrate of Calocybe indica for removing Iron from some contaminated Water Samples

Preparation of PVP-BiOBr Adsorbent for Efficient Indigo Carmine Dye Removal Using Flow-Circulation Systems.

This work presents an adsorptive removal of indigo carmine (IC) dye using a polyvinylpyrrolidone capped bismuth oxybromide (PVP-BiOBr) adsorbent. PVP-BiOBr was synthesized via a simple precipitation method. The morphology and surface chemical structure of the adsorbent were characterized using XRD, SEM, FTIR, and BET analyses. The adsorption isotherm and kinetics were investigated to reveal the mechanism of dye removal. Prepared PVP-BiOBr has a crystallite size of 19.7 nm, with a mean particle size of ∼2 μm and a surface area of 5.14 m2 g-1. The optimum pH for this adsorptive process spanned the range of 4 to 9. Experimental data indicated applicability of the Langmuir isotherm model, and the study confirms a pseudo-second-order kinetics model. The maximum adsorption capacity for IC dye was 208.3 mg g-1. A flow-circulation system was developed for the treatment of IC dye contaminated water samples. PVP-BiOBr was packed inside a column and did not spill into the water sample after treatment. The removal efficiency was ≥90% after 25 min. The PVP-BiOBr adsorbent could be reused for three cycles. This work demonstrates that PVP-BiOBr is a promising candidate as an adsorbent for IC dye removal. Additionally, the flow-based system establishes an automated operation in continuous mode, which is viable for large scale applications.

Fabrication and Advanced Imaging Characterization of Magnetic Aerogel-Based Thin Films for Water Decontamination.

Aerogels have emerged as appealing materials for various applications due to their unique features, such as low density, high porosity, high surface area, and low thermal conductivity. Aiming to bring the advantages of these materials to the environmental field, this study focuses on synthesizing magnetic silica aerogel-based films suitable for water decontamination. In this respect, a novel microfluidic platform was created to obtain core-shell iron oxide nanoparticles that were further incorporated into gel-forming precursor solutions. Afterward, dip-coating deposition was utilized to create thin layers of silica-based gels, which were further processed by 15-hour gelation time, solvent transfer, and further CO2 desiccation. A series of physicochemical analyses (XRD, HR-MS FT-ICR, FT-IR, TEM, SEM, and EDS) were performed to characterize the final films and intermediate products. The proposed advanced imaging experimental model for film homogeneity and adsorption characteristics confirmed uniform aerogel film deposition, nanostructured surface, and ability to remove pesticides from contaminated water samples. Based on thorough investigations, it was concluded that the fabricated magnetic aerogel-based thin films are promising candidates for water decontamination and novel solid-phase extraction sample preparation.

Environmental Surveillance of Legionella spp. in an Italian University Hospital: results of 7 years of analysis.

Nosocomial structures pose a high risk of Legionella spp. contamination due to complex water systems with challenging disinfection; moreover, the risk of severe legionellosis as a consequence of nosocomial exposure is very high in settings characterized by vulnerable patient conditions. In the present work, we described the results of 7 years of environmental surveillance in a reference hospital in Liguria, in which a specific water safety plan (WSP) has been implemented in 2017, including data collected during the COVID-19 pandemic. During the study period, 1190 water samples were collected, of which 277 (23.3%) tested positive for Legionella spp. Positive samples with concentration values above 1,000 CFU/l were 184 (66.4%). Based on the new structure categorization contained in the WSP, hospital buildings classified as at "very high" risk resulted the most affected structures over the entire study period; however, the absolute number of positive samples greatly decreased over time, from 61 contaminated water samples in 2017 to only 9 in 2023. Our findings prompted the reinforcement of control and prevention measures, affirming the appropriateness of risk-category classification. Indeed, the majority of contamination cases were associated with the water networks of buildings classified as "very high" risk.

Synergistic CdS@CeO2 nanocomposites: Harnessing Z-scheme electron transfer for enhanced photocatalytic CO2 conversion and aqueous Cr(VI) reduction

The present work describes the fabrication of CdS-D@CeO2 Z-scheme heterojunctions as highly stable, efficient and recyclable photocatalysts for the visible light assisted reduction of CO2 to methanol as well as Cr(VI) to Cr(III). The bare CeO2 produced methanol with the rate of 111 μmolh−1g−1 that is much lower in comparison to CdS-D@CeO2 (501 μmolh−1g−1). In addition, the photocatalytic efficiency remained nearly same for three successive runs, indicating the higher stability and recycling ability of the heterojunctions CdS-D@CeO2. It was also observed that under direct sunlight irradiation, CdS-D@CeO2 efficiently reduced 100% Cr(VI) to Cr(III) in an aqueous medium in just 40 minutes. Moreover, >95% removal was maintained even after 5 catalytic cycles. Additionally, for mimicking real contaminated water samples, the influence of the foreign ions on Cr(VI) reduction was evaluated by using lake water sample and no adverse effects on the result were observed. Thus, this work showed a way to develop cost-effective, easily synthesized, durable and recyclable composite photocatalysts for CO2 utilization and proficient removal of waste water pollutants by employing the clean, green, and renewable solar energy.

Polyurethane sponges bearing cucurbituril adsorb Cr(III) and Pb(II) ions from contaminated water samples.

Water contamination with toxic metals causes harmful effects on the environment and to human health. Although cucurbiturils have carboxyl groups in their portal that can interact with metal ions, there is a lack of studies about their use as metal adsorbent. This scenario has motivated conduction of the present study, which addresses the use of cucurbit[6]uril (CB[6]) and cucurbit[8]uril (CB[8]) for adsorbing Pb and Cr from water samples, in free forms and immobilized in poly(urethane) sponges. The adsorption kinetics revealed that CB[8] leads to faster adsorption compared to CB[6], with equilibrium achieved in 8h for CB[8] and 48h for CB[6] for both metals, and achieved up to 80% of decrease in metal concentration. The Langmuir isotherm model provided a better description of adsorption for Cr and Pb in CB[6] and Pb in CB[8] with a maximum concentration adsorbed of 32.47mgg-1 for Pb in CB[6], while the Dubinin-Radushkevich model was more suitable for Cr adsorption in CB[8]. Sponges containing CB[6] and CB[8] have proven to be efficient for Pb and Cr remediation in tannery effluent samples, reducing Cr and Pb concentration by 42 and 33%, respectively. The results indicate that CB[6] and CB[8], whether used in their pure form or integrated into sponges, exhibit promising potential for efficiently adsorbing metals in aqueous contaminated environments.

Cork-Activated Carbon as a Sorptive Phase for Microextraction of Emerging Contaminants in Water Samples

A novel strategy for microextraction of emerging contaminants was developed by using cork activated carbon (CAC) as the sorbent phase. Carbonization of the natural phase increased the surface area and the porosity of the material, thus improving the extraction efficiency. Moderately polar compounds, such as ibuprofen and its metabolites, were used as model analytes in water samples. Rotating disk sorptive extraction (RDSE) together with gas chromatography‒mass spectrometry (GC‒MS) were used for extraction and determination of the analytes, respectively. The optimum conditions for the material synthesis were 600 °C, K2CO3 as the activating agent and a mass ratio of 0.8:1 (activating agent:raw material). The optimum values for the RDSE were pH 2, a sample volume of 25 mL and an extraction time of 90 min. The absolute recovery rates for ibuprofen and its metabolites ranged from 19 to 55%, and the relative standard deviations were between 3 and 13%. The proposed method was used to measure the analytes in the influent and effluent from a wastewater treatment plant in Santiago, Chile. The concentrations found for ibuprofen and its metabolites were 0.98–9.8 µg L-1 and 0.8–8.6 µg L-1 in the influent and effluent, respectively. Activation of the cork material enabled the synthesis of a sorbent phase with sorption efficiencies similar to those obtained with the commercial octadecylsilane (C18) phase and superior to that observed for styrene-divinylbenzene (S-DVB). This process is simple and cost-effective.

A sustainable redox-active electrocatalyst utilizing natural quercetin-infused MWCNT for ultra-sensitive detection of environmental Cr(VI) contaminants

Hexavalent chromium (Cr(VI)), classified as a Group 1 carcinogen, is a widely acknowledged water pollutant, posing significant public health risks. The persisting challenge involves the development of sensitive and cost-effective methods for the detection and monitoring of Cr(VI) species at the concentration level recommended by the World Health Organization (WHO), which is 50 ppb (960 nM), in water sources. In the electrochemical detection of Cr(VI), modified electrodes utilizing precious metals (Au and Ag) and toxic organic redox mediators (Thionine, methylene blue, quionone, bisphenol and phenosafranine) have been employed. In this work, as an new platform, green electrochemical approach based on parsley-plant based natural quercetin (Qn-Redox) infused MWCNT modified glassy carbon electrode, designated as GCE/MWCNT@Qn-Redox, has been introduced for highly-effective electrocatalytic reduction and sensing of Cr(VI) species in pH 2 KCl-HCl solution. The as prepared GCE/MWCNT@Qn-Redox showed highly redox active surface confined peak at Eo = 0.550 V vs Ag/AgCl with surface excess value, 10.31 × 10−9 mol cm−2. Extensive physicochemical, spectroscopic, molecular characterization, and electrochemical control experiments confirm the identity of the entrapped molecular species in the green electrode as quercetin. By using scanning-electrochemical technique, the electroactive site of the green-electrode was imaged using Fe(CN)63−/Fe(CN)64− redox couple. The green-electrode showed excellent electrocatalytic Cr(VI) reduction signal where the Qn-Redox peak appears without any fouling problem. As a practical application, a portable batch-injection analysis coupled with three-in-one screen-printed electrode modified with MWCNT@Qn-Redox, which exhibitted a detection limit of 203 nM (S/N = 3), has been demonstrated for real time monitoring of toxic Cr(VI) species in tannery industries contaminated water samples. Given the electrochemical foundation of this approach, it holds promise for various sustainable electroanalytical assays in the future.

Water Sterilization using Ultraviolet Light-Emitting Diodes

In order to provide adequate living conditions, it is crucial for each building to have access to essential utilities such as water, electricity, and sewage systems. In some regions, they may experience isolation, but they can still establish connections to distribution networks and fulfill basic living requirements. In such cases, local solutions like wells and septic tanks are implemented. The water sourced from these sources contains a multitude of viruses and bacteria that can have a detrimental effect on the health of anyone who consumes it. Numerous water filtration/sterilization options are available on the market, but they come with significant installation, maintenance, and operating expenses. The use of ultraviolet C (UVC) rays generated by mercury lamps for sterilization by irradiation is becoming increasingly popular due to its cost-effectiveness in terms of installation and maintenance. The main drawbacks of this technique are the high energy consumption and the potential danger of mercury exposure. This article describes the processes for designing, making, and testing two water filtration probes that use light-emitting diodes (LED) diodes to emit UVC rays. This solution lowers energy consumption eliminates the risk of mercury contamination, and leads to a decrease in maintenance costs, as the lifespan of diodes is longer than that of mercury vapor lamps. The two probes have LED diodes that emit at a wavelength of 275 nm, with a total radiant flux of 12 mW and 100 mW, respectively. Biological tests were carried out in the laboratory to assess the effects of these probes on an artificially contaminated water sample. The results obtained are satisfactory and comparable to those of sterilization devices with LED lamps.

New carbon-based voltammetric sensor modified with multi-walled carbon nanotubes decorated with europium oxide to determine triclosan

Triclosan is used in hygiene products and cosmetics, due to its antimicrobial action. The emergence of the Covid-19 pandemic at the beginning of 2020, there was an increase in the consumption of products composite also with TCS, such as hand antiseptics, alcohol gel and liquid soap, which means a risk of streams contamination higher. In this work, a new carbon-based voltammetric sensor modified with multi-walled carbon nanotubes (MWCNT) decorated with Eu2O3 nanoparticles, was developed to quantify TCS in water samples. Based on the electrochemical reaction of the TCS in the electro active area of the sensor, an analytical curve was obtained using the sensor with best analytical performance, it was successfully applied to assess the presence of TCS in water samples. By the results it can be noted an increase in the electrochemical area of the modified sensor and a decrease in the resistance to charge transfer, providing an increase in the sensitivity of the developed sensor, which proved to be very selective, accurate and easy to reproduce. The results show that the proposed voltammetric sensor has excellent catalytic activity with a wide detection range (3.8 × 10−7 and 1.8 × 10−5 mol L−1), and an ultrasensitive limit of detection (LOQ) and quantification (LOQ) (2.3 × 10−9 and 7.6 × 10−9 mol L−1, respectively). The proposed sensor was applied to determine TCS in groundwater and river. The recovery rates obtained were 97.5–102.2% for previously contaminated water samples. The results allow us to conclude that the developed sensor presents itself as an option for TCS detection.

Optical fiber immunosensors based on surface plasmon resonance for the detection of Escherichia coli.

Every year, millions of people suffer some form of illness associated with the consumption of contaminated food. Escherichia coli (E. coli), found in the intestines of humans and other animals, is commonly associated with various diseases, due to the existence of pathogenic strains. Strict monitoring of food products for human consumption is essential to ensure public health, but traditional cell culture-based methods are associated with long waiting times and high costs. New approaches must be developed to achieve cheap, fast, and on-site monitoring. Thus, in this work, we developed optical fiber sensors based on surface plasmon resonance. Gold and cysteamine-coated fibers were functionalized with anti-E. coli antibody and tested using E. coli suspensions with concentrations ranging from 1 cell/mL to 105 cells/mL. An average logarithmic sensitivity of 0.21 ± 0.01 nm/log(cells/mL) was obtained for three independent assays. An additional assay revealed that including molybdenum disulfide resulted in an increase of approximately 50% in sensitivity. Specificity and selectivity were also evaluated, and the sensors were used to analyze contaminated water samples, which verified their promising applicability in the aquaculture field.

Synergism between polyethyleneimine, graphene oxide, and MgFeAl-layered triple hydroxide in removing acid red 1 dye and bisphenol A from contaminated water samples

Water pollution is rapidly growing, requiring the development of effective treatment processes. In this work, a novel adsorbent (composed of polyethyleneimine, graphene oxide, MgFeAl-layered triple hydroxide, abbreviated as PEI@GO/MgFeAl-LTH) was synthesized, characterized, and applied to remove two hazardous water pollutants (i.e., acid red 1 and bisphenol A). The adsorption performance of the synthesized PEI@GO/MgFeAl-LTH nanocomposite was benchmarked to its parental materials (i.e., GO, PEI@GO, MgFeAl-LTH, and GO/MgFeAl-LTH). The results demonstrated that the adsorption capacity of bisphenol A (BPA) and acid red 1 (AR1) onto the nanocomposite are 352.0 and 155.5 mg/g, respectively, which are higher than their adsorption on GO, PEI@GO, MgFeAl-LTH, and GO/MgFeAl-LTH. The obtained adsorption isotherms and kinetics data were fitted using different models, which showed that Redlich-Peterson isotherm and Avrami kinetics models provide excellent fits for the obtained experimental data; the other models provided mixed results. The zeta potential measurements and the study of the pH effect suggest that the adsorption of BPA and AR1 onto the PEI@GO/MgFeAl-LTH nanocomposite is governed by more than a single mechanism. Furthermore, thermodynamics analysis demonstrated that the adsorption of AR1 and BPA is an exothermic (the respective ∆H values are −27.59 and −11.21 kJ/mol), spontaneous, and physical in nature. With respect to the reusability of this nanocomposite, the results revealed that it is highly stable and easily regenerable using a cheap solvent (i.e., 0.2 M NaOH). Accordingly, this study demonstrates the efficacy and superiority of the synthesized PEI@GO/MgFeAl-LTH nanocomposite in efficiently capturing toxic organic pollutants from aqueous environments.

Effective solid–solid and microwave-assisted formation of folic acid@titanium oxide nanoparticles for enhanced batch adsorptive uptake of toxic Cd(II) and Cu(II) pollutants

Synthesis of complicated multi-constituent nanocomposites for adsorption, removal and photocatalytic decomposition of miscellaneous pollutants is a tedious process with respect to the cost of synthesis, methodology and characterization of the produced materials. To find out a simple, short, and direct approach for preparation of an efficient nanomaterial from only two components is a challenging target. Therefore, it is aimed in this investigation to design and generate a potential nanosorbent by only combination of folic acid (Fol-Ac) with titanium oxide nanoparticles (TiO2NPs) via simple solid–solid and microwave-assisted formation of a novel Fol-Ac@TiO2NPs nanosorbent in less than 15 min. The assembled nanosorbent was confirmed by determination of the surface coverage using thermal gravimetric analysis 187.4 mg/g (425.6 µmol g−1), homogenous particles distribution with average particle size (56.92–96.74 nm) based on the TEM imaging. The surface was loaded with several effective and related functional groups to Fol-Ac and TiO2NPs as detected from the FT-IR analysis. The characterized Fol-Ac@TiO2NPs was then used as a novel nanosorbent to capture Cd(II) as a highly toxic divalent metal ion and Cu(II) as a moderately toxic ion via batch mode under the contribution of numerous experimental parameters. Zero charge point of Fol-Ac@TiO2NPs was identified at pHPZC = 6.6 to match with the optimum capture at pH 6.0–7.0 for both Cd(II) plus Cu(II) pollutants. Other parameters as reaction time and temperature as well as metal concentration were also performed and modeled to characterize the possible mechanisms via evaluation of the kinetic, thermodynamic and adsorption isotherm investigations, respectively. Fol-Ac@TiO2NPs nanosorbent was efficiently recycled providing 96.67–97.03 % and 91.34–92.47 % stability after the first and fifth cycles, respectively. Moreover, the efficient usage of Fol-Ac@TiO2NPs for uptake of Cd(II) plus Cu(II) pollutants from contaminated water samples was successfully performed providing 98.32–83.97 % and 93.45–83.39 %, respectively.

Determination of 90Sr in highly radioactive aqueous samples via conversion to a kinetically stable 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid complex followed by concentration–separation–fractionation based on capillary electrophoresis–liquid scintillation

BackgroundThe Fukushima Daiichi Nuclear Power Plant accident (2011) released large amounts of radioactive substances into the environment and generated highly radioactive debris. Post-accident countermeasures are currently in the phase of fuel debris removal, which requires the analysis of radioactive contaminants in the environment and fuel. The spectra of solely β-emitting nuclides, such as 90Sr, overlap; thus, an effective method for nuclide separation is desired. Since conventional methods for high-dose sample analysis pose substantial exposure risks and generate large amounts of secondary radioactive waste, faster procedures allowing for decreased radiation emission are highly desirable. ResultsIn this study, we developed a 90Sr2+ quantitation technique based on liquid scintillation counting (LSC)–coupled capillary transient isotachophoresis (ctITP), along with two-point detection and relying on the rapid concentration, separation, and fractionation of 1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid (DOTA)-complexed 90Sr2+ in a single run. The applicability of our method for the analysis of real-world samples was verified by conducting addition-recovery experiments using a seawater reference material and radioactive liquid waste obtained from the radioactive waste treatment facility at the Japan Atomic Energy Agency. The recovery determined by LSC was 95–113%, indicating successful quantitative analysis. 90Sr recovery was determined to be 90.1% from a contaminated water sample obtained from the Fukushima Daiichi Nuclear Power Plant, which was analyzed using the standard addition of 90Sr. The sensitivity (detection limit = 0.016 Bq) of the proposed method on a radioactivity basis was equal to or higher than that of the conventional method using ion exchange-LSC (0.012–0.07 Bq). Significance and noveltyOur method allows for the handling of high-dose radioactive samples at the microliter level and is substantially faster than conventional ion exchange protocols, whereas ctITP has not been used for practical applications due to inaccurate collection and lack of a suitable chemical system. The concentration–separation–fractionation protocol in ctITP is successful due to the existence of a rare inert Sr2+ complex and precise fractionation. This study establishes a pathway toward safer and more practical analysis of radionuclides.