Ionic liquid mediated extraction, assisted by ultrasound energy, of available/mobilizable metals from sediment samples

Utilization of Extraction Procedures for Evaluating Environmental Risk from Waste Materials

Several procedures for extracting content from different waste materials types were investigated, with the aim of evaluating their environmental impact. The waste materials consisted of wastes from bauxite ore processing by means of the Bayer process (red mud, Ajka, Hungary), bauxite ore using the sintering process followed by the Bayer process (brown-red mud, Žiar nad Hronom, Banská Bystrica region, Slovakia) and sulphide ores (metal-rich post-flotation tailing, Lintich, Slovakia). The extraction procedures were carried out with the aim of isolating "mobilizable" fractions using 0.05 M ethylenediaminetetraacetic acid (EDTA) and 0.43 M acetic acid (AA) (representing environmental risk during changes in normal environmental conditions) and "maximum potentially mobilizable" fractions using 2 M HNO3 (representing the total environmental risk). The content of chosen toxic heavy metals (THMs) (Cd, Cr, Cu, Pb, Ni, Zn) and Fe, Mn as metals creating Fe/Mn oxides in the extracts and solutions after microwave digestion was determined using high-resolution continuum source flame atomic absorption spectrometry (HR CS FAAS). On the basis of the results obtained in this study, it is possible to state that different origin of waste materials is reflected in different mobility of toxic heavy metals into the surrounding environment. From the point of view of toxic heavy metals mobility, disposal site of wastes after bauxite processing are much less of a threat to the environment than disposal site of flotation sludge after processing sulphide ores. The single extraction of 0.43 M AA is more effective than the extraction of 0.05 M EDTA for the purposes of determining the content of metals in the mobilizable fraction of tailing waste materials. The mobility of the studied toxic heavy metals in the Lintich tailing decreases in the direction from the lagoon to the dam, which may indicate the fact that the dam serves to a certain extent to inhibit the mobility of metals into the surrounding ecosystem.

Recent Progress on Ex Situ Remediation Technology and Resource Utilization for Heavy Metal Contaminated Sediment

Sediment is an important part of aquatic systems, which plays a vital role in transporting and storing metals. Due to its abundance, persistence, and environmental toxicity, heavy metal pollution has always been one of the hot spots in the world. In this article, the state-of-art ex situ remediation technology for metal-contaminated sediments is elaborated, including sediment washing, electrokinetic remediation (EKR), chemical extraction, biological treatment, as well as encapsulating pollutants by adding some stabilized/solidified materials. Furthermore, the progress of sustainable resource utilization methods, such as ecosystem restoration, construction materials (e.g., materials fill materials, partition blocks, and paving blocks), and agriculture use are reviewed in detail. Finally, the pros and cons of each technique are summarized. This information will provide the scientific basis for selecting the appropriate remediation technology in a particular scenario.

The use of ultrasound in the South Cone region. Advances in organic and inorganic synthesis and in analytical methods

In organic and inorganic synthesis and in analytical methods, an external conventional heat source is usually applied to carry out a chemical reaction at a high temperature, or an extraction procedure. In the last decades, the use of ultrasound as an alternative energy source has become an interesting field of research in these topics in the South Cone region (Argentina, Chile, Uruguay, Southern Brazil and Paraguay). For this reason, the present review, covering the period 2009 to mid-2021, is a compilation of ultrasound-assisted synthetic and analytical methodologies.

Sustainable ex-situ remediation of contaminated sediment: A review

Routine waterway dredging activities generate huge volumes of dredged sediment. The remediation of dredged contaminated sediment is a worldwide challenge. Novel and sustainable ex-situ remediation technologies for contaminated sediment have been developed and adopted in recent years. In this review paper, the state-of-art ex-situ treatment technologies and resource utilisation methods for contaminated sediment were critically reviewed. By applying different techniques, sediment could been successfully transformed into sustainable construction materials, such as ceramsite, supplementary cementitious materials, fill materials, paving blocks, partition blocks, ready-mixed concrete, and foamed concrete. We highlighted that proper remediation technologies should be cleverly selected and designed according to the physical and chemical characteristics of sediment, without neglecting important aspects, such as cost, safety, environmental impacts, readiness level of the technology and social acceptability. The combination of different assessment methods (e.g., environmental impact assessment, cost-benefit analysis, multi-criteria decision analysis and life cycle assessment) should be employed to comprehensively evaluate the feasibility of different sustainable remediation technologies. We call on the scientific community in a multidisciplinary fashion to evaluate the sustainability of various remediation technologies for contaminated sediment.

Fast and easily obtained information about mobilizable metals from sediment samples. Extraction assisted by benzothiophene-based ionic liquids

A fast and easy method for trace metal extraction on sediments was developed in our laboratories. Three new stable S-metylbenzothiophenium salts were employed along with microwaves to modify the BCR protocol to obtain the concentration of metals of the first two fractions in only one step. The optimum conditions were obtained with 0.125 g of sediment irradiated at 250 W for 30 s at 120 °C, in 5 ml of an aqueous mixture of 10 mM of 1,2-dimethylbenzothiophenium tetrafluoroborate and 0.5 M of hydroxylamine chlorhydrate at pH 2. The method validation was carried out employing BCR 701. The extracted metals were determined by ICP OES. A student's paired t-test was applied with the reference method, giving satisfactory results.

Deep Eutectic Solvent Based Air Assisted Ligandless Emulsification Liquid-Liquid Microextraction for Preconcentration of Some Heavy Metals in Biological and Environmental Samples

In this study, a deep eutectic solvent (DES) based on air-assisted ligandless emulsification liquid-liquid microextraction method (DES-AA-LL-ELLME) was considered for preconcentration and extraction of some metals (Cd, Ni, Pb and Cu). A 1:1 mixture of the synthesized DES and triethylamine was added as an extractant to extract metal ions in the absence of chelating agent. Tetrahydrofuran as the aprotic solvent provided a turbid state. To disperse the aggregated DES droplets into the aqueous phase, air-assisted was performed. The influence of several effective parameters was monitored. Under optimum conditions, limits of detection were found in the range of 0.31-0.99 µg L^-1 with preconcentration factor from 67 to 69. The relative standard deviation (n = 10) was in the range of 2.1%-3.1% for all analytes. This procedure was applied to determine some metals in both biological and environmental samples with appropriate recoveries about 98.7%-106%.

Ultrasound augmented leaching of nickel sulfate in sulfuric acid and hydrogen peroxide media

A new method of preparation high purity nickel sulfate assisted by ultrasonic was studied. The process mechanism was analyzed by Inductively Coupled Plasma (ICP), X-ray diffraction (XRD), Scanning electron microscopy (SEM), and Energy dispersive X-ray spectrometry (EDS).The reaction mechanisms of oxidizing leaching and ultrasonic leaching were explored, respectively. Results showed that ultrasonic treatment peel off the oxide film on the surface of nickel. The leachate under strongly agitated, the yield rate of nickel sulfate was accelerate. And the reaction area was increased by the cavitation effect, the liquid-solid reaction was promoted, and the activation energy was reduced. The leaching rate of nickel reached 46.29% by conventional leaching, which takes about 5h. Under the same conditions, the ultrasonic leaching rate reached 40%, only half of the conventional leaching time. Concentration of leaching agent, reaction temperature, ultrasonic power, leaching time had significant effect on the enhancement of the leaching reaction with ultrasonic radiation. The leaching rate of 60.41% under the optimum experiment conditions as follows: sulfuric acid concentration 30%, hydrogen peroxide 10%, leaching temperature 333K, ultrasonic power 200W and leaching time 4h. The kinetic study of the system was investigated, and the reaction rates of conventional leaching and ultrasonic leaching were controlled by diffusion, and the apparent activation energies were 16.2kJ/mol and 11.83kJ/mol.

Fe3O4/hydroxyapatite/graphene quantum dots as a novel nano-sorbent for preconcentration of copper residue in Thai food ingredients: Optimization of ultrasound-assisted magnetic solid phase extraction

Fe₃O₄/hydroxyapatite/graphene quantum dots (Fe₃O₄/HAP/GQDs) nanocomposite was synthesized and used as a novel magnetic adsorbent. This nanocomposite was characterized using scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, energy dispersive X-ray spectroscopy, and magnetization property. The Fe₃O₄/HAP/GQDs was applied to pre-concentrate copper residues in Thai food ingredients (so-called "Tom Yum Kung") prior to determination by inductively coupled plasma-atomic emission spectrometry. Based on ultrasound-assisted extraction optimization, various parameters affecting the magnetic solid-phase extraction, such as solution pH, amount of magnetic nanoparticles, adsorption and desorption time, and type of elution solvent and its concentration were evaluated. Under optimal conditions, the linear range was 0.05-1500ngmL^-1 (R²>0.999), limit of detection was 0.58ngmL^-1, and limit of quantification was 1.94ngmL^-1. The precision, expressed as the relative standard deviation of the calibration curve slope (n=5), for intra-day and inter-day analyses was 0.87% and 4.47%, respectively. The recovery study of Cu for real samples was ranged between 83.5% and 104.8%. This approach gave the enrichment factor of 39.2, which guarantees trace analysis of Cu residues. Therefore, Fe₃O₄/HAP/GQDs can be a potential and suitable candidate for the pre-concentration and separation of Cu from food samples. It can easily be reused after treatment with deionized water.