Buse Tuğba Zaman

"Rare earth elements, a group of 17 elements found in the Earth’s crust, are classified by international organizations and countries as critical and strategic raw materials due to their unique physical and chemical properties. Rare earth elements have applications in many fields, ranging from the defence industry to agriculture. The increasing global demand in rare earth elements has led to the excessive use and environmental dispersal of these elements. In this context, their increasing use has raised concerns regarding environmental toxicity. Accurately detecting these elements at trace levels with high sensitivity and precision is crucial for protecting the environment and human health. To this end, various instruments, including inductively coupled plasma optical emission spectrometry (ICP-OES), inductively coupled plasma mass spectrometry (ICP-MS), and X-ray fluorescence spectrometry (XRF), are used for their detection and quantification. Although these instruments have their own unique advantages, they face challenges such as low analyte concentrations and interference effects from diverse matrixes. To overcome these disadvantages, various preconcentration and separation methods are employed. Among these methods, solid-phase extraction (SPE) methods are frequently preferred sample preparation techniques because they offer high recovery results and extraction efficiency specific to the analytes. In this method, many innovative new sorbent materials are being designed, synthesized, and made available for use. This review focuses on new sorbent materials and SPE based methods reported over the past decade for the application of various rare earth elements. The increasing interest in the determination of rare earth elements in environmental, biological, and geological samples in recent years has made the development of innovative analytical strategies in this field crucial. Future studies should focus on the synthesis of new, low-cost, environmentally friendly, and highly selective sorbent materials, enabling the accurate and reliable determination of trace and ultra-trace rare earth elements."

In our study, a rapid, low-cost analytical method was developed for the colorimetric determination of Sn(IV) using silver nanoparticles (AgNPs) synthesized with clove extract. The AgNPs synthesized have a surface plasmon resonance peak at 425 nm. When Sn(IV) standards at increasing concentrations are added to samples containing AgNPs, a color change proportional to the analyte concentration occurs. With increasing Sn(IV) concentration, the absorbance of the AgNPs decreases. In the analyses, the absorbance change based on analyte concentration was monitored. The detection limit of the developed method was calculated as 7.9 µM with the linear range as 20–300 µM. The analytical performance of the method in complex matrix media was demonstrated by conducting recovery experiments in tap water. Our percentage recovery value varies between 97% and 118.0%. The toxicological behavior of the AgNPs were also evaluated in Daphnia magna (D. magna) to justify the safety and ecotoxicity of the synthesized nanoparticles. According to the results, LC₅₀ was calculated as 0.2 mg L⁻¹ for 96 h.

Gold is abundant in nature, however, precise and reliable analytical methods for its detection are required stemming from its increasing prevalence in environmental, biological, and industrial systems, as well as the growing interest in understanding its function in living organisms and its effects on human health. This study investigates the use of biogenically synthesized silver nanoparticles (AgNPs) for the preconcentration and determination of gold ions prior to determination by UV-Vis spectrophotometry. AgNPs were synthesized by reducing silver nitrate through the use of an apricot kernel extract as both reducer and stabilizer agent. The colloidal yellowish AgNPs interacted with gold ions, leading to a distinct color change and a considerable decrease in the surface plasmon resonance (SPR) intensity at 415 nm in the UV-Vis absorption band, indicating a highly sensitive and selective colorimetric detection of gold ions. Under optimized conditions, the proposed method achieved satisfactory limit of detection (LOD) and limit of quantification (LOQ) values of 2.9 and 9.7 mg/L, respectively. A matrix matching calibration strategy was used to enhance quantification accuracy, resulting in satisfactory percent recoveries from waste mud samples (88–112%). Overall, the results validated the developed method as a green, simple, rapid, and accurate analytical approach to the determination of gold.

Toxic metals are known pollutants to pose high toxicity to the environment and humans when they occur above threshold levels. In order to meet the requirements of environmental quality standards established by pertinent regulations, analytical processes that perform quick, accurate, and precise determination of such pollutants are becoming more and more important. This study offers a rapid, efficient, and sensitive method for cadmium determination in tap water samples by slotted quartz tube–flame atomic absorption spectrometry (SQT-FAAS). A spray-assisted droplet formation-liquid phase microextraction (SADF-LPME) method was developed to simultaneously extract and preconcentrate cadmium ions using microliter volumes of solvent in agreement with green analytical chemistry. Hydrazone type complexing ligand and diphenylcarbazone were tried to check the complex formation efficiencies. The optimum extraction conditions were determined by comprehensive examination of the parameters affecting complexation and extraction. The limit of detection/limit of quantification values for the DPC and L-4 hydrazone ligands under optimum conditions were 0.70/2.4 µg/L and 1.1/3.5 µg/L, respectively. The linear dynamic range for cadmium was found to be 2.0–75 µg/L, and the correlation coefficient (R²) was higher than 0.99. The method has been successfully applied to tap water samples, with recovery results close to 100% validating the accuracy of the method.

The present study demonstrates a treatment approach that utilizes flower-shaped tin oxide nanoparticles for the removal of cadmium from synthetic wastewater by adsorption. Tin oxide nanoparticles were synthesized using a simple and eco-friendly method and employed for the removal of cadmium ions from wastewater. The nanoflowers were successfully characterized using Fourier Transform Infrared Spectroscopy, X-Ray Diffraction Analysis, Scanning Electron Microscope and Brunauer-Emmett-Teller (BET) surface area analysis. The batch adsorption process was optimized by response surface methods to investigate the influential parameters of the adsorption process. Optimal removal efficacy was achieved at a pH value of 9.0, a mixing time of 20 min, and an adsorbent amount of 15 mg. The results indicated that the adsorbent achieved a maximum removal efficiency of 99.14 ± 0.10% for Cd(II)ions in domestic wastewater. The adsorption equilibrium process was elucidated by Langmuir, Freundlich, Sips and Toth isotherm models using nonlinear regression. In addition, error functions such as Chi-square (X², Average Relative Error (ARE), Root Mean Squared Error (RMSE) and HYBRID were used to test the validity of the nonlinear models. The results indicated that the Sips model, with an R² value of 0.9894, accurately matched the experimental data and adsorption capacity of 57.12 mg g^− 1 for Cd(II) was calculated respectively. The sorption kinetics were well characterized by a pseudo-second-order kinetic model. The results demonstrated that adsorption of cadmium onto the surface of SnO₂ nanoparticles is influenced by both monolayer adsorption and multi-site interactions. These findings indicate that SnO₂ nanoparticles are suitable for removing cadmium from aqueous solutions in batch processes.

In this study, a preconcentration strategy based on Ni(OH)₂ nanoflowers (NFs) was developed for the extraction/separation of bismuth ions from environmental water samples before the determination by flame atomic absorption spectrometry (FAAS). The homogeneous coprecipitation method was employed for the synthesis of the flower-shaped Ni(OH)₂ and used as an adsorbent for the preconcentration of bismuth. The extraction variables were determined by a univariate optimization strategy to obtain maximum extraction performance. The optimal parameters of the method were as follows: 15 min mechanical shaking at 120 rpm, pH 6.0 buffer solution (1.0 mL), 20 mg of sorbent, and 250 µL of 6.0 M nitric acid for the elution. Under the optimized instrumental and extraction conditions, LOD (limit of detection), LOQ (limit of quantitation), and linear dynamic range were determined as 2.8 µg/L, 9.4 µg/L, and 0.010–0.30 mg/L, respectively. The enhancement factor of the sorbent-based method was calculated as 139.1-folds by comparing the slopes of calibration plots obtained from FAAS and the preconcentration method. To assess the feasibility and reliability of the developed method, tap water and spring water samples were analyzed under optimized conditions. The satisfactory %recoveries were obtained close to 100% using the direct comparison method. The obtained results show that the presented method is a promising candidate for efficient extraction and trace determination of bismuth in several sample mediums.

In recent years, pollutants released into the environment from various sources threaten environmental health. Rapid industrialization and the constantly increasing needs of people facilitate the release of more hazardous wastes into the ecosystem. The presence of pollutants in water resources causes a wide range of adverse effects. In this study, calcium phosphate nanomaterial (Ca₃(PO₄)₂ NM) was synthesized from biological waste eggshells for the cadmium removal in synthetic domestic wastewater, and a treatment method was developed using these NMs. The Ca₃(PO₄)₂ NMs were produced by using a biowaste which provides the synthesis procedure greener approach. The biogenic NMs were used to remove toxic cadmium ions from wastewater samples. Cytotoxicity and genotoxicity studies of the synthesized NMs were also carried out, and their possible effects on the health of living organisms and the ecology were examined. In the developed method, the parameters affecting the removal of cadmium from wastewater samples were optimized and the removal efficiency was calculated by determining cadmium in a flame atomic absorption spectrophotometer system (FAAS). Synthetic domestic wastewater samples were utilized for evaluating the applicability of the developed treatment strategy. In addition, the adsorption capacity of the material for Cd²⁺ ion was calculated and the values obtained were modeled by using Langmuir adsorption isotherm (LAI). The calculated LAI parameters were within the appropriate limits, which proved that the developed NM can be used as an effective material for cadmium removal. Moreover, a new, rapid, and feasible synthesis strategy for the synthesis of Ca₃(PO₄)₂ NM was presented in the literature. Graphical abstract

Industrial activities can release a variety of harmful substances, including organic and inorganic components, into the environment. Inadequate treatment and discharge of these pollutants into aquatic environments might have adverse effects. Cadmium (Cd) is a toxic element found in various environmental sources, both anthropogenic and geogenic, which can contaminate soils and groundwater crucial for providing healthy food and safe drinking water. This study aimed to develop a novel strategy by the help of nano-sized adsorbents to remove cadmium ions from wastewater through batch-type adsorption processes. CuFe₂O₄ nanoparticles having high magnetic properties were synthesized using a co-precipitation process for the efficient removal of analyte. Characterization of the nanomaterial was performed using field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD), and Brunauer–Emmett–Teller (BET) analysis. Method effective parameters were systematically optimized through univariate experiments to find proper conditions for the improvement of interaction between the adsorbent and cadmium ions. Removal efficiency (%RE) of Cd was assessed by using synthetic wastewater samples, and the accuracy/practicability of the recommended method proved highly efficient within the linear range of flame atomic absorption spectrophotometry (FAAS). In addition, the Langmuir isotherm model was applied to the experimental data, and the effective adsorption of cadmium from synthetic wastewater by the magnetic CuFe₂O₄ nanoparticles was proved.