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Advanced Analytical Techniques in Environmental Chemistry

A special issue of Molecules (ISSN 1420-3049). This special issue belongs to the section "Cross-Field Chemistry".

Deadline for manuscript submissions: closed (28 June 2023) | Viewed by 19790

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Guest Editor
INCDO-INOE 2000 Research Institute for Analytical Instrumentation Cluj-Napoca, Ploiesti, Romania
Interests: trace elements analysis in environmental samples using advanced analytical techniques; miniaturized spectrometric instrumentation; passive sampling using the diffusive gradients in thin-films (DGT) technique; development and validation of spectrometric methods for environmental applications; elements bioavailability in soil and water; materials characterization using spectrometric techniques
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Special Issue Information

Dear Colleagues,

Environmental analysis covers soil, water, air, and biological matrices, while target analytes include naturally occurring substances and contaminants resulting from anthropogenic activities. Particular challenges in environmental matrix analysis are introduced by the very low concentrations at which some compounds should be measured, the different oxidation states in which analytes are found, and the forms in which a particular analyte (which influence its mobility and bioavailability) is present. Another subject of interest in environmental analysis is the development of analytical protocols that correspond to the principles of “green chemistry”. This involves both sample preparation methodologies and instrumental detection. In terms of instrumentation, this refers mainly to miniaturization and automatization to reduce energy, reagent volumes, sample sizes, waste, and the use of multi-analyte or multi-parameter methods. In terms of sample preparation methodologies, reducing the pretreatment stages as much as possible, lowering the reagent volume, and avoiding or replacing toxic reagents are desirable. As a result, there is a continuous research interest in the development, validation, and application of new analytical techniques with improved performance characteristics for environmental quality characterization. There is a permanent demand to develop and use methods that ensure reliable and dependable analytical data. In order to achieve this, method validation is an essential component that a laboratory should implement. Considering these aspects, this Special Issue is addressed to scientists working on the development, validation, and application of advanced analytical methods designed for environmental quality assessment. The main topics covered in this Special Issue are: (I) environmentally friendly sample preparation methodologies; (II) analytical instrumentation with improved performance parameters; (III) methodologies for element speciation; (III) methodologies for in situ analysis/monitoring; (IV) development and validation of analytical methods to ensure quality performances for environmental sample analysis; (V) application of advanced analytical techniques for environmental quality assessment.

Dr. Marin Senila
Guest Editor

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Keywords

  • advanced analytical instrumentation
  • speciation analysis
  • method validation
  • green analytical chemistry
  • environmental quality assessment
  • pollutant bioavailability
  • safe reagents
  • performance parameters

Published Papers (11 papers)

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Research

23 pages, 12544 KiB  
Article
Adsorption of Basic Yellow 28 and Basic Blue 3 Dyes from Aqueous Solution Using Silybum Marianum Stem as a Low-Cost Adsorbent
by Türkan Börklü Budak
Molecules 2023, 28(18), 6639; https://doi.org/10.3390/molecules28186639 - 15 Sep 2023
Cited by 1 | Viewed by 782
Abstract
In the present study, the ability of an adsorbent (SLM Stem) obtained from the stem of the Silybum Marianum plant to treat wastewater containing the cationic dyes basic blue 3 (BB3) and basic yellow 28 (BY28) from aqueous solutions was investigated using a [...] Read more.
In the present study, the ability of an adsorbent (SLM Stem) obtained from the stem of the Silybum Marianum plant to treat wastewater containing the cationic dyes basic blue 3 (BB3) and basic yellow 28 (BY28) from aqueous solutions was investigated using a batch method. Then, the SLM Stem (SLM Stem-Natural) adsorbent was carbonized at different temperatures (200–900 °C) and the removal capacity of the products obtained for both dyes was examined again. The investigation continued with the product carbonized at 800 °C (SLM Stem-800 °C), the adsorbent with the highest removal capacity. The dyestuff removal studies were continued with the SLM Stem-Natural and SLM Stem-800 °C adsorbents because they had the highest removal values. The surface properties of these two adsorbents were investigated using IR, SEM, and XRD measurements. It was determined that the SLM Stem-Natural has mainly non-porous material, and the SLM Stem-800 °C has a microporous structure. The optimal values for various parameters, including adsorbent amount, initial dye solution concentration, contact time, temperature, pH, and agitation speed, were investigated for BY28 dye and were 0.05 g, 15 mg/L, 30 min, 40 °C, pH 6 and 100 rpm when SLM Stem-Natural adsorbent was used and, 0.15 g, 30 mg/L, 30 min, 40 °C, pH 10, and 150 rpm when SLM Stem-800 °C adsorbent was used. For BB3 dye, optimal parameter values of 0.20 g, 10 mg/L, 30 min, 25 °C, pH 7, and 100 rpm were obtained when SLM Stem-Natural adsorbent was used and 0.15 g, 15 mg/L, 40 min, 40 °C, pH 10, and 100 rpm when SLM Stem-800 °C adsorbent was used. The Langmuir isotherm described the adsorption process best, with a value of r2 = 0.9987. When SLM Stem-800 °C adsorbent was used for BY28 dye at 25 °C, the highest qm value in the Langmuir isotherm was 271.73 mg/g. When the study was repeated with actual water samples under optimum conditions, the highest removal for the BY28 dye was 99.9% in tap water with the SLM Stem-800 °C adsorbent. Furthermore, the reuse study showed the adsorbent’s efficiency even after three repetitions. Full article
(This article belongs to the Special Issue Advanced Analytical Techniques in Environmental Chemistry)
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14 pages, 1313 KiB  
Article
Development and Validation of a New UFLC–MS/MS Method for the Detection of Organophosphate Pesticide Metabolites in Urine
by Dileshwar Kumar, Sukesh Narayan Sinha and Kasturi Vasudev
Molecules 2023, 28(15), 5800; https://doi.org/10.3390/molecules28155800 - 1 Aug 2023
Viewed by 1186
Abstract
To monitor human exposure to pesticides, experts commonly measure their metabolites in urine, particularly dialkyl phosphates (DAPs), which include diethyl phosphate (DEP), Diethyl thiophosphate (DETP), diethyl dithiophosphate (DEDTP), dimethyl phosphate (DMP), dimethyl thiophosphate (DMTP) and dimethyl dithiophosphate (DMDTP)to monitor the metabolites of organophosphates. [...] Read more.
To monitor human exposure to pesticides, experts commonly measure their metabolites in urine, particularly dialkyl phosphates (DAPs), which include diethyl phosphate (DEP), Diethyl thiophosphate (DETP), diethyl dithiophosphate (DEDTP), dimethyl phosphate (DMP), dimethyl thiophosphate (DMTP) and dimethyl dithiophosphate (DMDTP)to monitor the metabolites of organophosphates. These DAP metabolites are a urinary biomarker for assessing pesticide exposure and potential health risks. This study presented a new screening method combining ultrafast liquid chromatography with tandem mass spectrometry (UFLC–MS/MS) to detect six DAP metabolites in human urine. The study also compared standard sample extraction methods, namely, liquid–liquid extraction (LLE); quick, easy, cheap, effective, ruggedand safe (QuEChERS); and lyophilization. After a comprehensive analysis of the methods used to extract the analytes, including recovery rate, repeatability and reproducibility, the liquid–liquid extraction (LLE) method was found to be the best. It had a high recovery rate, was easy to handle, required less sample volume and had a short extraction time. Therefore, the LLE method was chosen for further analysis. The results showed excellent performance with high recoveries between 93% and 102%, precise repeatability (RSD) between 0.62% and 5.46% and acceptable reproducibility values (RSD) between 0.80% and 11.33%. The method also had limits of detection (LOD) ranging from 0.0201 ng/mL to 0.0697 ng/mL and limits of quantification (LOQ) ranging from 0.0609 ng/mL to 0.2112 ng/mL. Furthermore, the UFLC–MS/MS method was validated based on the SANTE guidance and successfully analyzed 150 urine samples from farmers and non-farmers. This validated method proved useful for biomonitoring studies focusing on OP pesticide exposure. It offers several advantages, such as a reduced need for samples, chemicals and materials, and a shorter analysis time. The method is sensitive and selective in detecting metabolites in human urine, making it a valuable approach for the practical and efficient assessment of pesticide exposure. Full article
(This article belongs to the Special Issue Advanced Analytical Techniques in Environmental Chemistry)
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13 pages, 1454 KiB  
Article
Impact of Low Lithium Concentrations on the Fatty Acids and Elemental Composition of Salvinia natans
by Anamaria Iulia Török, Ana Moldovan, Lacrimioara Senila, Eniko Kovacs, Maria-Alexandra Resz, Marin Senila, Oana Cadar, Claudiu Tanaselia and Erika Andrea Levei
Molecules 2023, 28(14), 5347; https://doi.org/10.3390/molecules28145347 - 11 Jul 2023
Viewed by 947
Abstract
The photosynthetic pigments, protein, macro and microelements concentrations, and fatty acids composition of Salvinia natans, a free-floating aquatic plant, were analyzed after exposure to Hoagland nutrient solution containing 1, 3, and 5 mg/L Li. The Li content of Salvinia natans grew exponentially [...] Read more.
The photosynthetic pigments, protein, macro and microelements concentrations, and fatty acids composition of Salvinia natans, a free-floating aquatic plant, were analyzed after exposure to Hoagland nutrient solution containing 1, 3, and 5 mg/L Li. The Li content of Salvinia natans grew exponentially with the Li concentration in the Hoagland nutrient solution. The exposure to Li did not induce significant changes in Na, Mg, K, Cu, and Zn content but enhanced the Ba, Cr, Mn, Ni and Mo absorption in Salvinia natans. The most abundant fatty acids determined in oils extracted from Salvinia natans were C16:0, C18:3(n6), C18:2(n6), and C18:3(n3). The photosynthetic pigments did not change significantly after exposure to Li. In contrast, chlorophyll and protein content decreased, whilst monounsaturated and polyunsaturated fatty acids content increased after the exposure to 1 mg/L Li. The results indicated that Salvinia natans exposed to low Li concentrations may be a good source of minerals, omega 6 and omega 3. Full article
(This article belongs to the Special Issue Advanced Analytical Techniques in Environmental Chemistry)
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15 pages, 4060 KiB  
Article
Synthesis and Application of a New Polymer with Imprinted Ions for the Preconcentration of Uranium in Natural Water Samples and Determination by Digital Imaging
by Caio S. A. Felix, Adriano V. B. Chagas, Rafael F. de Jesus, Willams T. Barbosa, Josiane D. V. Barbosa, Sergio L. C. Ferreira and Víctor Cerdà
Molecules 2023, 28(10), 4065; https://doi.org/10.3390/molecules28104065 - 12 May 2023
Cited by 2 | Viewed by 1276
Abstract
This work proposes the synthesis of a new polymer with imprinted ions (IIP) for the pre-concentration of uranium in natural waters using digital imaging as a detection technique. The polymer was synthesized using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (Br-PADAP) for complex formation, ethylene glycol dimethacrylate (EGDMA) as [...] Read more.
This work proposes the synthesis of a new polymer with imprinted ions (IIP) for the pre-concentration of uranium in natural waters using digital imaging as a detection technique. The polymer was synthesized using 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (Br-PADAP) for complex formation, ethylene glycol dimethacrylate (EGDMA) as a crosslinking reagent, methacrylic acid (AMA) as functional monomer, and 2,2′-azobisisobutyronitrile as a radical initiator. The IIP was characterized by Fourier transform infrared spectroscopy and scanning electron microscopy (FTIR). Uranium determination was performed using digital imaging (ID), and some experimental conditions (sample pH, eluent concentration, and sampling flow rate) were optimized using a two-level full factorial design and Doelhert response surface methodology. Thus, using the optimized conditions, the system allowed the determination of uranium with detection and quantification limits of 2.55 and 8.51 µg L−1, respectively, and a pre-concentration factor of 8.2. All parameters were determined using a 25 mL sample volume. The precision expressed as relative deviation (RSD%) was 3.5% for a solution with a concentration of 50 µg L−1. Given this, the proposed method was used for the determination of uranium in four samples of natural waters collected in the city of Caetité, Bahia, Brazil. The concentrations obtained ranged from 35 to 75.4 μg L−1. The accuracy was evaluated by the addition/recovery test, and the values found ranged between 91 and 109%. Full article
(This article belongs to the Special Issue Advanced Analytical Techniques in Environmental Chemistry)
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20 pages, 2941 KiB  
Article
A Multi-Method Approach for Impact Assessment of Some Heavy Metals on Lactuca sativa L.
by Maria-Loredana Soran, Aura Nicoleta Sîrb, Ildiko Lung, Ocsana Opriş, Otilia Culicov, Adina Stegarescu, Pavel Nekhoroshkov and Delia-Maria Gligor
Molecules 2023, 28(2), 759; https://doi.org/10.3390/molecules28020759 - 12 Jan 2023
Cited by 6 | Viewed by 1373
Abstract
Heavy metals represent a large category of pollutants. Heavy metals are the focus of researchers around the world, mainly due to their harmful effects on plants. In this paper, the influence of copper, cadmium, manganese, nickel, zinc and lead, present in soil in [...] Read more.
Heavy metals represent a large category of pollutants. Heavy metals are the focus of researchers around the world, mainly due to their harmful effects on plants. In this paper, the influence of copper, cadmium, manganese, nickel, zinc and lead, present in soil in different concentrations (below the permissible limit, the maximum permissible concentration and a concentration higher than the maximum permissible limit) on lettuce (Lactuca sativa L.) was evaluated. For this purpose, the authors analyzed the variation of photosynthetic pigments, total polyphenols, antioxidant activity and the elemental content in the studied plants. The experimental results showed that the variation of the content of biologically active compounds, elemental content and the antioxidant activity in the plants grown in contaminated soil, compared to the control plants, depends on the type and concentration of the metal added to the soil. The biggest decrease was recorded for plants grown in soil treated with Ni I (−42.38%) for chlorophyll a, Zn II (−32.92%) for chlorophyll b, Ni I (−40.46%) for carotenoids, Pb I (−40.95%) for polyphenols and Cu III (−29.42%) for DPPH. On the other hand, the largest increase regarding the amount of biologically active compounds was registered for Mn I (88.24%) in the case of the chlorophyll a, Mn I (65.56%) for chlorophyll b, Pb I (116.03%) for carotenoids, Ni III (1351.23%) for polyphenols and Ni III (1149.35%) for DPPH. Full article
(This article belongs to the Special Issue Advanced Analytical Techniques in Environmental Chemistry)
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20 pages, 3684 KiB  
Article
How Well Do We Handle the Sample Preparation, FT-ICR Mass Spectrometry Analysis, and Data Treatment of Atmospheric Waters?
by Lucas Pailler, Pascal Renard, Edith Nicol, Laurent Deguillaume and Angelica Bianco
Molecules 2022, 27(22), 7796; https://doi.org/10.3390/molecules27227796 - 12 Nov 2022
Cited by 1 | Viewed by 1533
Abstract
FT-ICR MS (Fourier-transform ion cyclotron resonance mass spectrometry) analysis has shown great potential to aid in the understanding of the extremely high molecular diversity of cloud water samples. The main goal of this work was to determine the differences in terms of formula [...] Read more.
FT-ICR MS (Fourier-transform ion cyclotron resonance mass spectrometry) analysis has shown great potential to aid in the understanding of the extremely high molecular diversity of cloud water samples. The main goal of this work was to determine the differences in terms of formula assignment for analytical (i.e., measurement replicates) and experimental replicates of a given cloud water sample. The experimental replicates, obtained by solid phase extraction, were also compared to the results obtained for freeze-dried samples to evaluate whether the presence of salts interferes with the analysis. Two S/N ratios, generally adopted for atmospheric samples, were evaluated, and three different algorithms were used for assignment: DataAnalysis 5.3 (Bruker), Composer (Sierra Analytics), and MFAssignR (Chemical Advanced Resolution Methods Lab). In contrast to other works, we wanted to treat this comparison from the point of view of users, who usually must deal with a simple list of m/z ratios and intensity with limited access to the mass spectrum characteristics. The aim of this study was to establish a methodology for the treatment of atmospheric aqueous samples in light of the comparison of three different software programs, to enhance the possibility of data comparison within samples. Full article
(This article belongs to the Special Issue Advanced Analytical Techniques in Environmental Chemistry)
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19 pages, 4445 KiB  
Article
High-Pressure Supercritical CO2 Pretreatment of Apple Orchard Waste for Carbohydrates Production Using Response Surface Methodology and Method Uncertainty Evaluation
by Lacrimioara Senila, Daniela Alexandra Scurtu, Eniko Kovacs, Erika Andrea Levei, Oana Cadar, Anca Becze and Cerasel Varaticeanu
Molecules 2022, 27(22), 7783; https://doi.org/10.3390/molecules27227783 - 11 Nov 2022
Cited by 2 | Viewed by 1273
Abstract
This study’s objective was to separate cellulose, hemicellulose, and lignin after high-pressure supercritical carbon dioxide pretreatment for further valorization. The study investigated the supercritical carbon dioxide pretreatment of apple orchard waste at temperatures of 160–200 °C, for 15–45 min, at a pressure of [...] Read more.
This study’s objective was to separate cellulose, hemicellulose, and lignin after high-pressure supercritical carbon dioxide pretreatment for further valorization. The study investigated the supercritical carbon dioxide pretreatment of apple orchard waste at temperatures of 160–200 °C, for 15–45 min, at a pressure of 10 MPa. Response Surface Methodology (RSM) was used to optimize the supercritical process and to improve its efficiency. The change of functional groups during different pretreatment conditions was examined by Fourier transform infrared (FTIR) spectroscopy. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) confirmed the structural changes in the biomass structure before and after pretreatment. A new ultra-high performance liquid chromatography (UHPLC) coupled with an evaporative light scattering detector (ELSD) method was developed and validated for the determination of carbohydrates in the liquid fraction that resulted after pretreatment. The estimated uncertainty of the method ranged from 16.9 to 20.8%. The pre-treatment of high-pressure supercritical CO2 appears to be an effective and promising technique for the recovery of sugars and secondary by-products without the use of toxic solvents. Full article
(This article belongs to the Special Issue Advanced Analytical Techniques in Environmental Chemistry)
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13 pages, 1731 KiB  
Article
Labeling Microplastics with Fluorescent Dyes for Detection, Recovery, and Degradation Experiments
by Zhiqiang Gao, Kendall Wontor and James V. Cizdziel
Molecules 2022, 27(21), 7415; https://doi.org/10.3390/molecules27217415 - 1 Nov 2022
Cited by 11 | Viewed by 3717
Abstract
Staining microplastics (MPs) for fluorescence detection has been widely applied in MP analyses. However, there is a lack of standardized staining procedures and conditions, with different researchers using different dye concentrations, solvents, incubation times, and staining temperatures. Moreover, with the limited types and [...] Read more.
Staining microplastics (MPs) for fluorescence detection has been widely applied in MP analyses. However, there is a lack of standardized staining procedures and conditions, with different researchers using different dye concentrations, solvents, incubation times, and staining temperatures. Moreover, with the limited types and morphologies of commercially available MPs, a simple and optimized approach to making fluorescent MPs is needed. In this study, 4 different textile dyes, along with Nile red dye for comparison, are used to stain 17 different polymers under various conditions to optimize the staining procedure. The MPs included both virgin and naturally weathered polymers with different sizes and shapes (e.g., fragments, fibers, foams, pellets, beads). We show that the strongest fluorescence intensity occurred with aqueous staining at 70 °C for 3 h with a dye concentration of 5 mg/mL, 55 mg/mL, and 2 µg/mL for iDye dyes, Rit dyes, and Nile red, respectively. Red fluorescent signals are stronger and thus preferred over green ones. The staining procedure did not significantly alter the surface, mass, and chemical characteristics of the particles, based on FTIR and stereomicroscopy. Stained MPs were spiked into freshwater, saltwater, a sediment slurry, and wastewater-activated sludge; even after several days, the recovered particles are still strongly fluoresced. The approach described herein for producing customized fluorescent MPs and quantifying MPs in laboratory-controlled experiments is both straightforward and simple. Full article
(This article belongs to the Special Issue Advanced Analytical Techniques in Environmental Chemistry)
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12 pages, 1181 KiB  
Article
Ultrasound-Assisted Dispersive Liquid-Liquid Microextraction Using Deep Eutectic Solvents (DESs) for Neutral Red Dye Spectrophotometric Determination
by Sana Ullah, Hameed Ul Haq, Muhammad Salman, Faheem Jan, Faisal Safi, Muhammad Balal Arain, Muhammad Shahzeb Khan, Roberto Castro-Muñoz and Grzegorz Boczkaj
Molecules 2022, 27(18), 6112; https://doi.org/10.3390/molecules27186112 - 19 Sep 2022
Cited by 8 | Viewed by 2184
Abstract
Deep eutectic solvents (DES), which have low toxicity and are low cost, biodegradable, and easily synthesized, were used for the extraction of neutral red (NR) dye before its spectrophotometric analysis. DES, containing choline chloride as a hydrogen bond acceptor and phenol as a [...] Read more.
Deep eutectic solvents (DES), which have low toxicity and are low cost, biodegradable, and easily synthesized, were used for the extraction of neutral red (NR) dye before its spectrophotometric analysis. DES, containing choline chloride as a hydrogen bond acceptor and phenol as a hydrogen bond donor with a molar ratio of 1:2, was used for the extraction of NR dye from aqueous media. The possible interaction of different DESs with NR was studied using density functional theory (DFT) calculations. Experimentally, a UV-visible spectrophotometer was used for the quantitative analysis. The most important parameters affecting method performance, such as pH, extraction temperature, DES type, its volume, THF volume, sonication time, and centrifugation time, were optimized. The developed method provides exceptional sensitivity in terms of LOD and LOQ, which were 2.2 and 7.3 µg/L respectively. The relative standard deviation was 1.35–1.5% (n = 10), and the pre-concentration factor was 40. The method was found to be linear in the range of 2–300 µg/L (R2 = 0.9967). The method was successfully used for the determination of NR in wastewater samples. Finally, the DES-based method presents operational simplicity, high sensitivity, and rapid determination (<5 min) compared with other analytical procedures. Full article
(This article belongs to the Special Issue Advanced Analytical Techniques in Environmental Chemistry)
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20 pages, 5199 KiB  
Article
Simultaneous Removal of Heavy Metals (Cu, Cd, Cr, Ni, Zn and Pb) from Aqueous Solutions Using Thermally Treated Romanian Zeolitic Volcanic Tuff
by Marin Senila, Emilia Neag, Oana Cadar, Emoke Dalma Kovacs, Ioan Aschilean and Melinda Haydee Kovacs
Molecules 2022, 27(12), 3938; https://doi.org/10.3390/molecules27123938 - 20 Jun 2022
Cited by 17 | Viewed by 2870
Abstract
Increased concentrations of heavy metals in the environment are of public health concern, their removal from waters receiving considerable interest. The aim of this paper was to study the simultaneous adsorption of heavy metals (Cu, Cd, Cr, Ni, Zn and Pb) from aqueous [...] Read more.
Increased concentrations of heavy metals in the environment are of public health concern, their removal from waters receiving considerable interest. The aim of this paper was to study the simultaneous adsorption of heavy metals (Cu, Cd, Cr, Ni, Zn and Pb) from aqueous solutions using the zeolitic volcanic tuffs as adsorbents. The effect of thermal treatment temperature, particle size and initial metal concentrations on the metal ions sorption was investigated. The selectivity of used zeolite for the adsorption of studied heavy metals followed the order: Pb > Cr > Cu > Zn > Cd > Ni. The removal efficiency of the heavy metals was strongly influenced by the particle sizes, the samples with smaller particle size (0–0.05 mm) being more efficient in heavy metals removal than those with larger particle size (1–3 mm). Generally, no relevant changes were observed in heavy metals removal efficiency for the treatment temperatures of 200 °C and 350 °C. Moreover, at a higher temperature (550 °C), a decrease in the removal efficiencies was observed. The Cd, Zn, Cu, Cr, Zn and Ni sorption was best described by Langmuir model according to the high values of correlation coefficient. The pseudo-first-order kinetic model presented the best correlation of the experimental data. Full article
(This article belongs to the Special Issue Advanced Analytical Techniques in Environmental Chemistry)
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14 pages, 2493 KiB  
Article
Characteristics of Volcanic Tuff from Macicasu (Romania) and Its Capacity to Remove Ammonia from Contaminated Air
by Marin Senila, Emilia Neag, Oana Cadar, Maria-Alexandra Hoaghia, Marius Roman, Ana Moldovan, Alexandru Hosu, Angela Lupas and Emoke Dalma Kovacs
Molecules 2022, 27(11), 3503; https://doi.org/10.3390/molecules27113503 - 30 May 2022
Cited by 6 | Viewed by 1576
Abstract
In the present work, the capability of the volcanic tuff from Macicasu (Romania) to remove ammonia (NH3) from air with different contamination levels during 24 h of adsorption experiments was investigated. The natural zeolitic volcanic tuff was characterized using X-ray diffraction [...] Read more.
In the present work, the capability of the volcanic tuff from Macicasu (Romania) to remove ammonia (NH3) from air with different contamination levels during 24 h of adsorption experiments was investigated. The natural zeolitic volcanic tuff was characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), the Brunauer–Emmett–Teller (BET) method, inductively coupled plasma optical emission spectrometry (ICP-OES), and thermogravimetric analysis (TGA). The adsorption capacities varied between 0.022 mg NH3 g−1 zeolite and 0.282 mg NH3 g−1 zeolite, depending on the NH3 concentrations in the air and at the contact time. The nonlinear forms of the Langmuir and Freundlich isotherm models were used to fit the experimental data. Additionally, the adsorption of NH3 was studied using nonlinear pseudo-first-order (PFO), pseudo-second-order (PSO), and Elovich kinetic model. Based on the total volume of pores of used volcanic tuff, the NH3 was removed from the air both due to the physical adsorption of NH3 gas and the ion exchange of NH4+ (resulted from a reaction between NH3 and H2O adsorbed by the zeolite). Depending on the initial NH3 concentration and the amount of volcanic tuff, the NH3 concentrations can be reduced below the threshold of this contaminant in the air. The adsorption capacity of NH3 per unit of zeolite (1 g) varied in the range of 0.022–0.282 mg NH3 g−1 depending on the NH3 concentration in the air. Full article
(This article belongs to the Special Issue Advanced Analytical Techniques in Environmental Chemistry)
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