A Complete Guide to Extraction Methods of Microplastics from Complex Environmental Matrices.

Sustainable development is a big global challenge for the 21st century. In recent years, a class of emerging contaminants known as microplastics (MPs) has been identified as a significant pollutant with the potential to harm ecosystems. These small plastic particles have been found in every compartment of the planet, with aquatic habitats serving as the ultimate sink. The challenge to extract MPs from different environmental matrices is a tangible and imperative issue. One of the primary specialties of research in environmental chemistry is the development of simple, rapid, low-cost, sensitive, and selective analytical methods for the extraction and identification of MPs in the environment. The present review describes the developments in MP extraction methods from complex environmental matrices. All existing methodologies (new, old, and proof-of-concept) are discussed and evaluated for their potential usefulness to extract MPs from various biotic and abiotic matrices for the sake of progress and innovation. This study concludes by addressing the current challenges and outlining future research objectives aimed at combating MP pollution. Additionally, a set of recommendations is provided to assist researchers in selecting appropriate analytical techniques for obtaining accurate results. To facilitate this process, a proposed roadmap for MP extraction is presented, considering the specific environmental compartments under investigation. By following this roadmap, researchers can enhance their understanding of MP pollution and contribute to effective mitigation strategies.

Optimization of Tensile Strength in the Paper Material Cutting Process Based on CO2 Laser Process Parameters.

This paper examines the impact of the CO2 laser parameters on the tensile strength, which is one of the most important properties of paper packaging in the process of cutting paper material. The study was performed on a paper material sample Fbb Board/Ningbo Spark C1S Ivory Board by examination of the influence of four independent variables: paper material grammage, cutting speed, laser power, and resolution on the tensile strength by using definitive screening design. Optimum process conditions of four variables that maximize the tensile strength were predicted and validated accordingly. Results confirm that laser power, paper material grammage, and cutting speed are the main process parameters that mostly affect the tensile strength. Besides individual parameters, two statistically significant interactions were obtained: laser power and cutting speed, and cutting speed and laser resolution. Maximum tensile strength values (20.37 N/mm) were achieved using the laser power of 60.6%, cutting speed of 3.24%, resolution of 2500 Hz, and a paper material grammage of 326.85 g/m2. With laser power at middle values and at a lower speed, a maximum tensile strength value can be obtained. Increasing the laser power and cutting speed will produce a slight lowering of tensile strength.

Synergistic effect of Fenton oxidation and adsorption process in treatment of azo printing dye: DSD optimization and reaction mechanism interpretation.

The main challenges to overcome within the Fenton process are the acidic pH as an optimal reaction condition, sludge formation in neutral pH medium and high toxicity of treated printing wastewater due to the generation of contaminating by-products. This research discusses the catalytic activity of homogeneous (FeSO4/H2O2) and heterogeneous (Fe2(MoO4)3/H2O2) Fenton processes in treatment of Yellow azo printing dye in synthetic aqueous solution and real printing effluent, with an integration of adsorption on functionalized biochar synthesized from wild plum kernels. The definitive screening design (DSD), was used to design the experiment. Independent variables were initial dye concentration (20-180 mg L-1), iron concentration (0.75-60 mg L-1), pH (2-10) and hydrogen peroxide concentration (1-11 mM). Higher decolourization efficiency of 79% was obtained within homogeneous Fenton treatment of printing wastewater, in comparison to heterogeneous Fenton treatment (54%), after a reaction time of 60 min. Same trend of mineralization degree was established: COD removal was 59% and 33% for homogeneous and heterogeneous Fenton process, respectively. The application of adsorption treatment has achieved significant advantages in terms of toxicity reduction (95%) and decolourization efficiency (90% of TOC removal and 22% of dye removal) of treated samples, even at neutral pH medium. Degradation mechanisms within Fenton and adsorption processes were proposed based on the qualitative gas chromatography/mass spectrometry analysis, physico-chemical properties of dye degradation products and functionalized biochar. Overall, the homogeneous Fenton/adsorption combined process can be potentially used as a treatment to remove azo dyes from contaminated water.

Application of UV-activated persulfate and peroxymonosulfate processes for the degradation of 1,2,3-trichlorobenzene in different water matrices.

The presence of a large number of micropollutants in the environment, including priority and emerging substances, poses a significant risk to surface and groundwater quality. Among them, trichlorobenzenes are widely used in the syntheses of dyes, pesticides, solvents, and other chemicals and have been identified as priority pollutants by the European Water Framework Directive. The main goal of this study was to investigate the behavior of 1,2,3-trichlorobenzene (TCB) during the sulfate radical-based advanced oxidation processes (SR-AOPs) involving UV activation of persulfate or peroxymonosulfate (UV/S2O82- and UV/HSO5- processes). For this purpose, TCB was subjected to SR-AOPs in synthetic water matrices containing humic acids or hydrogencarbonate and natural water samples and a comparative evaluation of the degradation process was made. The toxicity of the oxidation by-products was also assessed. The evaluation of TCB degradation kinetics results using principal component analysis indicates that the efficacy of the SR-AOPs was highly dependent on the pH, initial oxidant concentration, UV fluence, and matrix characteristics. In natural waters, TCB degradation by the UV/S2O82- process proved to be most effective in acidic conditions (pH 5), while the UV/HSO5- process showed the highest efficacy in basic conditions (pH 9.5), achieving a maximum TCB degradations of 97-99%. The obtained results indicate that UV/S2O82- and UV/HSO5- as new generation oxidation processes have significant potential for TCB removal from water and result in only minor toxicity after treatment (14-23% of Vibrio fischeri bioluminescence inhibition).

The Application of Solar Cells in the Electrokinetic Remediation of Metal Contaminated Sediments.

In this study, solar cells were used to generate an electric field for the electrokinetic remediation of metal contaminated sediment (Nickel, Cadmium, Zinc). For determination of metals mobility, bioavailability and potential toxicity, sequential extraction procedure, simultaneously extracted metals (SEM) and acid-volatile sulphide ratios (AVS) were performed before, during and after treatment.After 21 days of treatment, 63% Ni, 82% Cd and 58% Zn was removed from the anode region. The application of the electric field changed the chemical composition of the sediments. The risk assessment analysis based on pseudo total metals content, the risk assessment code and the relationship between SEM and AVS, indicates that a simple singular approach for risk assessment analysis and evaluation of the quality of sediments is not enough.

Degradation of anthraquinone dye reactive blue 4 in pyrite ash catalyzed Fenton reaction.

Pyrite ash (PA) is created by burning pyrite in the chemical production of sulphuric acid. The high concentration of iron oxide, mostly hematite, present in pyrite ash, gives the basis for its application as a source of catalytic iron in a modified Fenton process for anthraquinone dye reactive blue 4 (RB4) degradation. The effect of various operating variables such as catalyst and oxidant concentration, initial pH and RB4 concentration on the abatement of total organic carbon, and dye has been assessed in this study. Here we show that degradation of RB4 in the modified Fenton reaction was efficient under the following conditions: pH=2.5; [PA]0=0.2 g L(-1); [H2O2]0=5 mM and initial RB4 concentration up to 100 mg L(-1). The pyrite ash Fenton reaction can overcome limitations observed from the classic Fenton reaction, such as the early termination of the Fenton reaction. Metal (Pb, Zn, and Cu) content of the solution after the process suggests that an additional treatment step is necessary to remove the remaining metals from the water. These results provide basic knowledge to better understand the modified, heterogeneous Fenton process and apply the PA Fenton reaction for the treatment of wastewaters which contains anthraquinone dyes.

Use of fly ash for remediation of metals polluted sediment--green remediation.

The aim of this study was to determine the possibility of using fly ash and combination of kaolinite and fly ash for the solidification/stabilization (S/S) of Ni and Zn contaminated sediment from the Krivaja river basin (Serbia), which represents an extraordinary risk to the environment and belongs to the last quality class in the Serbian sediment classification. Fly ash was used as a stabilising agent because it occurs as a secondary industrial product, so in this way two types of waste are immobilized. Microwave assisted BCR sequential extraction procedure was employed to assess potential of Ni and Zn mobility and risk to the aquatic environment. In order to determine the long-term behavior of the S/S mixture, the semi-dynamic ANS 16.1 leaching test was performed. The existing leaching method was modified and acetic acid and humic acid were also used as leachants instead of deionised water, in order to simulate possible "worst case" leaching conditions for S/S waste being disposed of in a landfill environment (acid rain, floods, etc.). S/S effectiveness was evaluated by measuring the cumulative fractions of metals leached, effective diffusion coefficients - De and leachability indices - LX. X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray analyzer (EDS) along with leaching tests were implemented to elucidate the mechanisms responsible for immobilization of the Ni and Zn. The controlling leaching mechanism was found to be diffusion, in all treated samples. Overall, the test results indicated that S/S treatment was effective for immobilization of these two types of waste, and can be considered acceptable for "controlled utilization".

Correlation of different pollution criteria in the assessment of metal sediment pollution.

In this article an assessment of the sediment metal pollution (cadmium, copper, chromium, lead, nickel, zinc) in the Veliki Backi canal (Serbia) was carried out using pseudo-total metal content, contamination factor (CF), pollution load index (PLI) and enrichment factor (EF). The study also encompassed pore-water metal concentrations and an assessment of sediment pollution based on the analysis of simultaneously extracted metals (SEM), acid volatile sulphides (AVS) and the sequential extraction procedure. The concentrations of metals are likely to result in harmful effects based on the comparison with sediment quality guidelines (Dutch, Canadian, US EPA - United States Environmental Protection Agency). The ratio of simultaneously extracted metals and volatile acid sulphides was found to be greater than 1 in only one location, which is already recognized as a place of high risk based on the criteria applied. Other samples had Σ[SEM]/[AVS] < 1, despite their high risk classification based on the applied criteria. According to the sequential extraction procedure, zinc and nickel exhibit high risk in most samples, whereas other metals show low and medium risk. The CF values for Cr, Cu and Zn were > 6 in most samples, which denotes very high contamination by these metals. The PLI values indicated moderate and high pollution. The EF values for all metals studied except for Cd in some cases were >1.5, suggesting anthropogenic impact. The obtained results will be invaluable for future activities regarding sediment monitoring and will facilitate the selection of appropriate criteria when evaluating sediment quality.

Influence of pH and ozone dose on the content and structure of haloacetic acid precursors in groundwater.

This study investigated the effects of pH (6-10) and ozone dose [0.4-3.0 mg O(3)/mg dissolved organic carbon (DOC)] on the content and structure of haloacetic acid (HAA) precursors in groundwater rich in natural organic matter (NOM; DOC 9.85 ± 0.18 mg/L) during drinking water treatment. The raw water was ozonated in a 2 L glass column. NOM fractionation was carried out using XAD resins. HAA formation potential (HAAFP) was determined according to standard EPA Method 552. NOM characterization revealed it is mostly hydrophobic (65 % fulvic and 14 % humic acids). Hydrophobic NOM significantly influences HAA formation, as confirmed by the high HAAFP (309 ± 15 µg/L). Ozonation at pH 6-10 led to changes in NOM structure, i.e. complete humic acid oxidation, and increased the hydrophilic NOM fraction content (65-90 % achieved using 3.0 mg O(3)/mg DOC). The highest degree of NOM oxidation and HAA precursor removal was achieved at pH 10 (up to 68 % HAAFP). Ozonation pH influenced the distribution of HAA precursor content, as increasing the pH from 6 to 10 increased the reactivity of the hydrophilic fraction, with the HAAFP increasing from 19.1 ± 6.0 µg/mg DOC in raw water to 152 ± 8 µg/mg DOC in ozonated water. The degree of HAA precursor removal depends on the dominant oxidation mechanism, which is related to the applied ozone dose and the pH of the oxidation process. Ozonation at pH 10 favours the mechanism of radical NOM oxidation and was the most effective for HAAFP reduction, with the efficacy of the process improving with increasing ozone dose.

Quantifying the environmental impact of As and Cr in stabilized/solidified materials.

The assessment of the quality of sediment from the Great Backi Canal (Serbia) based on the pseudo-total As and Cr content according to the corresponding Dutch standards and Canadian guidelines showed its severe contamination with these two elements. Microwave assisted BCR sequential extraction procedure was employed to assess their potential mobility and risk to the aquatic environment. Comparison of the results of sequential extraction and different criteria for sediment quality assessment has led to somewhat contradictory conclusions. While the results of sequential extraction showed that Cr comes under the medium risk category, As shows no risk to the environment, despite of its high pseudo-total content. The contaminated sediment, irrespective of the different distribution of As and Cr, was subjected to the same immobilization, stabilization/solidification (S/S) treatment. Semi-dynamic leaching test was conducted for As and Cr contaminated sediment in order to assess the long-term leaching behavior of these elements. In order to simulate "worst case" leaching conditions, the test was modified using acetic acid and humic acid solution as leachants instead of deionized water. The effectiveness of S/S treatment was evaluated by determining diffusion coefficients. Four different single-step leaching tests were applied to evaluate the extraction potential of As and Cr. A diffusion-based model was used to elucidate the controlling leaching mechanisms. The test results indicated that all applied S/S treatments were effective in immobilizing As and Cr, irrespective of their different availabilities in the untreated samples. In most treated samples, the controlling leaching mechanism appeared to be diffusion, which indicates that a slow leaching of As and Cr could be expected.

Correlation between the results of sequential extraction and effectiveness of immobilization treatment of lead- and cadmium-contaminated sediment.

The assessment of the quality of sediment from the Great Backi Canal (Serbia), based on the pseudo-total lead (Pb) and cadmium (Cd) content according to the corresponding Dutch standards and Canadian guidelines, showed its severe contamination with these two metals. A microwave-assisted BCR (Community Bureau of Reference of the Commission of the European Union) sequential extraction procedure was employed to assess their potential mobility and risk to the aquatic environment. Comparison of the results of sequential extraction and different criteria for sediment quality assessment has led to somewhat contradictory conclusions. Namely, while the results of sequential extraction showed that Cd comes under the high-risk category, Pb shows low risk to the environment, despite its high pseudo-total content. The contaminated sediment, irrespective of the different speciation of Pb and Cd, was subjected to the same immobilization, stabilization/solidification (S/S) treatments using kaolinite, montmorillonite, kaolinite-quicklime, montmorillonite-quicklime, fly ash, zeolite, or zeolite-fly ash combination. Semi-dynamic leaching tests were conducted for Pb- and Cd-contaminated sediment in order to assess the long-term leaching behavior of these metals. In order to simulate "worst case" leaching conditions, the semi-dynamic leaching test was modified using 0.014 M acetic acid (pH = 3.25) and humic acid solutions (20 mg TOC l-1) as leachants instead of deionized water. The effectiveness of S/S treatment was evaluated by determining diffusion coefficients (De) and leachability indices (LX). The standard toxicity characteristic leaching procedure (TCLP) was applied to evaluate the extraction potential of Pb and Cd. A diffusion-based model was used to elucidate the controlling leaching mechanisms. Generally, the test results indicated that all applied S/S treatments were effective in immobilizing Pb and Cd, and the treated sediments may be considered acceptable for "controlled utilization" based on LX values, irrespective of their different availability in the untreated samples. In the majority of samples, the controlling leaching mechanism appeared to be diffusion, which indicates that a slow leaching of Cd and Pb could be expected when the above S/S agents were applied. The TCLP results showed that all S/S samples were nonhazardous.

Preliminary evaluation of galvanic sludge immobilization in clay-based matrix as an environmentally safe process.

This study attempts to determine the possibilities and limitations of the immobilization of galvanic wastes by their incorporation into clay-based materials. It focuses on the effects of several processing parameters such as the temperature of thermal treatment, the relative amount of sludge, and the physico-chemical aspects of the sample, on the fixing level of relevant metals (Zn, Ni, Fe, Mn, Pb, Cu, Cr) in thermally treated clay-based samples. The effectiveness of sludge inactivation was assessed by water-leaching test and conductivity measurements. In view of the potential use of the sludge stabilization products as construction materials, the linear shrinkage and bending strain of the fired samples was investigated. To characterize their morphology, mineralogy and composition, fired samples of clay and its mixtures with galvanic sludge were studied on a scanning electron microscope (SEM) coupled with an energy dispersive X-ray analyser (EDS) and X-ray diffractometer (XRD). It was found that the efficiency of metal immobilization is dependent on the clay composition and the temperature of the thermal treatment of the prepared mixtures. The thermal treatment of all samples at all temperatures resulted in the stabilization of all heavy metal ions (copper, nickel, iron, lead, manganese and zinc) with the exception of chromium.