Metal Desorption Research Articles

The Role of Surface Functional Groups of Iron Oxide, Organic Matter, and Clay Mineral Complexes in Sediments on the Adsorption of Copper Ions

Heavy metal pollution is a global problem affecting the environment and human health. Sediment is the source sink of heavy metals in water. Under certain circumstances, the migration of heavy metals will cause water pollution. Therefore, it is of great significance to study sediment composition and composite complexes in the migration and transformation of heavy metals. To understand the adsorption mechanisms of composite complexes and improve the theoretical understanding of adsorption in multi-component complex systems, this study explored the characteristics and rules of Cu adsorption to organic–inorganic, inorganic minerals, and iron-oxide–clay complexes in the estuary sediments of the Dianchi Lake. The Langmuir and Freundlich isotherm models were used for Cu adsorption experiments on three complexes to study their adsorption kinetics. X-ray diffraction and Fourier transform infrared spectroscopy characterized the samples before and after adsorption. The relationship between adsorption capacity and sediment composition was analyzed through redundant analyses. The results showed that the Freundlich isothermal model was better than the Langmuir model in describing the adsorption behavior of the adsorbents. The contribution of iron and aluminum oxides to Cu adsorption was more than that of organic matter. The organic–inorganic complexes functional groups involved in copper adsorption are the most, which resulting in a higher adsorption capacity. The organic matter removal (organic degradation in sediment) will reduce the polar functional groups and reduce silicide activity, leading to heavy metal desorption and re-entry into the water body.

Remediation of Pb (II), Cd (II), and Zn (II) from aqueous solutions using porous (styrene-divinylbenzene)/Cu-Ni bimetallic nanocomposite microspheres: continuous fixed-bed column study.

Bimetallic nanoparticles (BNPs) have been used as a new line of defence against heavy metal contamination among several types of nanoparticles (NPs) due to their enhanced, synergistic activity. In this study, we investigated the adsorption behaviour of porous (styrene-divinylbenzene)/CuNi bimetallic nanocomposite (P(St-DVB)/CuNi BNC) in a continuous flow fixed-bed column and its ability to remove Pb (II), Cd (II), and Zn (II) ions from aqueous solutions. We examined how the initial metal concentration, flow rate, and bed height affected the adsorption characteristics. Experimental results confirmed that the adsorption capacity increased with increase in influent metal concentration and bed height and decreased with increase in flow rate. The breakthrough and the column kinetic parameters were successfully predicted with three mathematical models: Thomas, Yoon-Nelson, and Adams-Bohart models. Both Thomas and Yoon-Nelson models showed good agreement with the experimental results for all the operating conditions. Successful desorption of heavy metals from the P(St-DVB)/CuNi BNC was performed using 0.5 M NaOH solution, and it showed good reusability of the adsorbent during four adsorption-desorption cycles. The results show that P(St-DVB)/CuNi BNC are effective and low-cost adsorbents, and they can be used in real-time large-scale industrial water treatment processes for the removal of heavy metals.

Origin of ironstones of the Udokan Cu deposit (Siberia, Russia): A key study using SEM and LA-ICP-MS

Iron is an important element involved in the formation of sedimentary-hosted copper deposits. Its accumulation in sedimentary basins and subsequent redistribution ultimately affect the position of copper mineralization. The Udokan copperstone deposit contains considerable Fe reserves as magnetite and hematite. The Fe oxides form disseminated and layered aggregates in both Cu-bearing horizons and host metasandstones. The layered aggregates of Fe oxides contain detrital (zircon, chromite and apatite) and authigenic (a Th silicate) components. The ironstones bear chemical features both of clastic and chemical sediments. The enrichment of ironstones in Cr, Zr and Hf is due to the presence of relics of detrital chromite and zircon. The presence of rare earth elements (REEs), U, and Th in composition of ironstones is a result of chemical precipitation/sorption.According to the LA-ICP-MS data, Al, Mg, and V are the most significant trace elements of magnetite, whereas Ti and V are hosted in hematite. The extremely high Ti, Cr and Cu contents of magnetite are associated with inclusions of minerals of these elements. In hematite, the high Ti contents are due to inclusions of rutile or titanite. The correlations between the trace elements in Fe oxides reflect the mineral assemblages characteristic of two stages of sediment transformation: (i) earlier diagenetic with the formation of a hematite-rutile assemblage and early Cu sulphides and Th and REE mineralization and (ii) later metamorphic, which is related to the formation of magnetite metacrysts and recrystallization of Cu sulphides.The Fe-rich sediments formed at a river–sea geochemical barrier as a result both of sedimentation of clastic Fe oxides and flocculation of dissolved iron. The maturation of gel and lithification of sediments were accompanied by desorption of metals that accumulated in the ferruginous sediments. Some of them formed the authigenic phases (like Th), while others were isomorphically incorporated in other authigenic minerals (e.g., Nb, Ta and Sn in rutile).

Performance of molybdenum vanadate loaded on bentonite for retention of cesium-134 from aqueous solutions

This article studied the sorption behavior of Cs(I) ions from aqueous solutions onto molybdenum vanadate@bentonite (MoV@bentonite) composite. MoV@bentonite has been fabricated using the precipitation method and was characterized by different analytical tools including, FT-IR, XRD, and SEM attached with an EDX unit. The sorption studies applied on Cs(I) ions include the effect of contact time, pH, initial metal concentrations, ionic strength, desorption, and recycling. The experimental results revealed that in the adsorption process carried out after equilibrium time (300 min), saturation capacity has a value of 26.72 mg·g−1 and the sorption of Cs(I) ions is dependent on pH values and ionic strength. Sorption kinetic better fit with the pseudo-second-order model; sorption isotherms apply to Langmuir, Freundlich, and Dubinin-Radushkevich (D-R) isotherm models. Data of thermodynamic parameters indicate that sorption is spontaneous and endothermic. Recycling experiments show that MoV@bentonite could be used for 7 cycles and the best eluant for the recovery of Cs(I) ions is 0.1 M HCl (76.9%). All the obtained data clarify that MoV@bentonite is considered a promising sorbent for the sorption of Cs(I) ions from aqueous solutions.

Kinetic and Equilibrium Studies on the Adsorption of Lead and Cadmium from Aqueous Solution Using Scenedesmus sp.

The current study aimed to investigate the viability and characteristics of Scenedesmus sp. as an adsorbent system to remove lead (Pb) and cadmium (Cd) through an in vitro exposure to a metal solution. In batch sorption experiments, the effects of pH, contact time, initial concentration of metal ions, and sorbent dosage on the adsorption process were trialed. The ideal biosorption conditions for each of the two metals were recorded. The biosorption process was quick, and the equilibrium times for the above-mentioned metals were recorded as 90 and 60 min, with removal percentages of 85% and 83%, respectively. The point zero charge of algal biomass was 4.5, which indicates a negative charge on the surface of the biosorbent. The model-based assessment of the biosorption process was revealed to have followed pseudo-second-order kinetics. The adsorption isotherms for lead and cadmium achieved a best fit with the Langmuir model, with monolayer biosorption capacities of 102 and 128 mg g−1, respectively. The desorption of both metals achieved more than 70% by using HCl. The FT-IR revealed the presence of hydroxyl and amine groups on the surface of the adsorbent that are involved in the biosorption process, and morphological changes were assessed by SEM. Hence, Scenedesmus sp. from a Himalayan provenance showed considerable promise as an alternate sorbent for the treatment of heavy-metal-contaminated wastewater.

О переработке ловозерского эвдиалитового концентрата методом сорбционной конверсии

The results of research on the development of the scientific foundations of the complex technology of processing Lovozersky eudialyte concentrate are summarized. The features of the concentrate composition are reported. The regularities of concentrate decomposition by sorption conversion with low-concentration solutions of mineral acids, desorption of metals from sulfocationite, stepwise hydrolytic deposition from eluates of concentrates of rare elements, the use of silicic acid transferred to solutions with simultaneous recirculation of acid solutions were studied. The outlines of the technology of complex processing of eudialyte concentrate are outlined, which provides for the production of concentrates of rare metals and the use of the main part of the silica and alkali metals contained in the concentrate.

Distinctive adsorption and desorption behaviors of temporal and post-treatment heavy metals by iron nanoparticles in the presence of microplastics

There are increasing concerns about microplastic (MP) pollution in the natural environment. Consequently, numerous physicochemical and toxicological studies have been conducted on the effects of MPs. However, few studies have concerned the potential impact of MPs on contaminated site remediation. We herein investigated the influence of MPs on the temporary and post heavy metal removal by iron nanoparticles, including pristine and sulfurized nano zero-valent irons (nZVI and S-nZVI). MPs inhibited adsorption of most heavy metals during the treatment of iron nanoparticles, and facilitated their desorption, such as Pb (II) from nZVI and Zn (II) from S-nZVI. However, such effects presented by MPs was usually less than those by dissolved oxygen (DO). Most desorption cases are irrelevant to the reduced formats of heavy metals involving redox reactions, such as Cu (I) or Cr (III), suggesting that the influence of MPs on metals are limited to those binding with iron nanoparticles through surface complexation or electrostatic interaction. As another common factor, natural organic matter (NOM) had almost no influence on the heavy metal desorption. These insights shed lights for enhanced remediation of heavy metals by nZVI/S-NZVI in the presence of MPs.

Characterization of ionic liquids removing heavy metals from electroplating sludge: Influencing factors, optimisation strategies and reaction mechanisms

The disposal of electroplating sludge (ES) is a common concern of researchers. Currently, it is difficult to achieve effective fixation of heavy metals (HMs) using traditional ES treatment. As green and effective HMs removal agents, ionic liquids can be used for the disposal of ES. In this study, 1-butyl-3-methyl-imidazole hydrogen sulphate ([Bmim]HSO4) and 1-propyl sulphonic acid-3-methyl imidazole hydrogen sulphate ([PrSO3Hmim]HSO4) were used as washing solvents for the removal of Cr, Ni, and Cu from ES. In reaction with increased agent concentration, solid–liquid ratio, and duration, the amount of HMs eliminated from ES rises, whereas opposite patterns were shown in response to rising pH. The quadratic orthogonal regression optimisation analysis also revealed that the ideal washing specifications for [Bmim]HSO4 were 60 g L−1, 1:40, and 60 min, respectively, for agent concentration, solid–liquid ratio, and washing time, while those for [PrSO3Hmim]HSO4 were 60 g L−1, 1:35, and 60 min, respectively. Under the optimal experimental conditions, the Cr, Ni, and Cu removal efficiencies for [Bmim]HSO4 were 84.3, 78.6, and 89.7%, respectively, and those values for [PrSO3Hmim]HSO4 were 99.8, 90.1, and 91.3%, respectively. This was mainly attributed to that ionic liquids enhance metal desorption through acid solubilisation, chelation, and electrostatic attraction. Overall, ionic liquids are reliable washing reagents for ES contaminated by HMs.

Brown Algal Residue for the Recovery of Metal Ions—Application to La(III), Cd(II), and Ni(II) Sorption

AbstractRemoving hazardous metals and recovering valuable strategic metals from wastewater has become an important challenge for the industry. Herein, brown algal biomass residue (AR, after bio‐stimulant extraction, currently poorly valorized) is tested for the removal of Ni(II), Cd(II), and La(III) from aqueous solutions. This valorization of industrial waste makes profit of residual amounts of alginate‐based materials, which have a strong affinity for metal cations. Fourier transform infrared (FTIR) and X‐ray photoelectron spectroscopy (XPS) techniques are used for characterizing metal/biosorbent interactions. Uptake kinetics are relatively fast (equilibrium being reached in 180–240 min). The Sips equation fits the sorption isotherms; the maximum sorption capacities at pH ≈5 reach up to 0.84 mmol La g−1, 0.92 mmol Cd g−1, and 0.78 mmol Ni g−1. In binary solutions, AR shows marked preference for La(III) over divalent cations. This selectivity may be increased by complexing base metals with EDTA, opening the route for the selective recovery of rare earth elements. HCl solution reveals more efficient (>90% for La(III), ≈82% for Cd(II) and Ni(II)) than CaCl2 solution at pH 2 for metal desorption. This waste residue from biostimulant extraction (in brown algal biomass) can be valorized for the recovery of hazardous and strategic metal ions.

Occurrence and distribution of geochemical elements in Miri estuary, NW Borneo: Evaluating for processes, sources and pollution status

In this study, estuarine water samples were collected at diverse hot spots in Miri River Estuary, East Malaysia to appraise the geochemical processes, which controls the river water quality. The collected water samples were analysed for various physicochemical parameters (insitu parameters, nutrients, major ions and trace metals), including stable isotopes (oxygen and hydrogen). Suspended solids are also extracted from the water samples and analysed for trace metals. Standard graphs, Piper plot, Gibbs diagram, water quality indices, geochemical modelling and statistical analysis were used for the data analysis. The acquired water quality data was compared with national and international guidelines for the suitability of water for various purposes. Interpretation of data reveals that the estuarine water quality is deemed unsuitable to be used for both drinking and irrigation purposes. Overall, the elemental concentrations are increasing from downstream to river mouth. Based on pollution indices (HEI and Cd), downstream region shows high vulnerability to metal pollution due to anthropogenic disturbance. Isotope values of river water indicate direct atmospheric precipitation with minimal evaporation. Factor analysis reveals that seawater influx, urban pollution, domestic and agricultural discharges at the downstream region are the main controlling factors to the river water quality. It is also deduced that suspended solids play a vital role in the adsorption and desorption of trace metals in the estuarine water. The outcome of this study provides a comprehensive information on pollution status of Miri estuary, which helps the policy makers to practice sustainable management of this water resource for Miri community.

The Application of Mineral Kaolinite for Environment Decontamination: A Review

Kaolinite clay mineral with a layered silicate structure is an abundant resource in China. Due to its advantages of excellent stability, high specific surface area and environmental friendliness, kaolinite is widely used in environment decontamination. By using kaolinite as a carrier, the photocatalytic technology in pure photocatalysts of poor activities, narrow spectral responses, and limited electron transport can be overcome, and the nano-Ag disinfectant’s limitation of the growth and aggregation of nanoparticles is released. Moreover, pure kaolinite used as an adsorbent shows poor surface hydroxyl activity and low cation exchange, leading to the poor adsorption selectivity and easy desorption of heavy metals. Current modification methods including heat treatment, acid modification, metal modification, inorganic salt modification, and organic modification are carried out to obtain better adsorption performance. This review systematically summarizes the application of kaolinite-based nanomaterials in environmental decontamination, such as photocatalytic pollutant degradation and disinfection, nano silver (Ag) disinfection, and heavy metal adsorption. In addition, applications on gas phase pollutant, such as carbon dioxide (CO2), capture and the removal of volatile organic compounds (VOCs) are also discussed. This study is the first comprehensive summary of the application of kaolinite in the environmental field. The review also illustrates the efficiency and mechanisms of coupling naturally/modified kaolinite with nanomaterials, and the limitation of the current use of kaolinite.

Microplastic and heavy metal interactions (adsorption and desorption) at different salinities

Heavy metals and microplastics (MPs) are two pollutants that are currently gaining a lot of attention, and it has been observed that they can interact. The objective of this research was to observe the adsorption and desorption of heavy metals concerning various types of MP particles, different heavy metals and concentrations, and salinity. The findings demonstrate that among all particle types, PP particles absorb heavy metals at the highest rate. Contrarily, PP particles release lower heavy metals and more slowly than other particles. Pb consistently absorbed more metal by MPs than Cu, Zn, or Cd. Cd had the highest rate of heavy metal desorption, followed by Pb, Cu, and Zn. The adsorption capacity of MPs particles increases together with the concentration of heavy metals, whereas the adsorption rate decreases. Salinity has an enormous impact on how MPs and heavy metals interact. The adsorption and desorption of heavy metal in MPs particles decreases and takes longer to reach equilibrium at increased salinities. Between the three different salinities, even the adsorption and desorption results demonstrate a significant difference (p<0.05). Finally, our results indicate that MPs particles have the potency as a vector for heavy metal in freshwater, brackish water, and ocean.

Микроэлементный состав донных отложений водных объектов в условиях городской застройки

Under the urbanization conditions there is an increase in the technogenic impact on water bodies, which is most clearly manifested in water bodies located on the territory of residential development. The value of reservoirs in cities lies in the possibility of using them as recreation places. Pollutants enter such water bodies with organized wastewater from industrial production and urban storm water. However, in a significant part of urban areas, the system of surface runoff is not organized. In this case, rain and snowmelt runoff enters water bodies disorderly (diffusely). Pollutants decrease the quality of natural waters, disrupt the functioning of aquatic ecosystems and reduce the self-purification ability. As a result, there is an intensification of the processes of eutrophication of water bodies, swamping and disturbance of local biocenoses. Pollutants entering surface water bodies accumulate in bottom sediments and create secondary pollution of rivers. Bottom sediments of reservoirs are accumulators of heavy metals. Due to sorption processes, water is purified from heavy metals, but under certain conditions the desorption of metals and their transition, when in the dissolved state, into the water column are observed, thus, secondary pollution occurs. In this study, the influence of the state of the catchment area on water quality in a reservoir, the content of pollutants in water and bottom sediments have been investigated. It is shown that the quality of water and bottom sediments in terms of content of chemical elements is determined by the type of anthropogenic load. For the river sections, not subject to technogenic load, the main influence is the state of the atmosphere and catchment area, from which the diffuse flow of rain and melt water occurs. The composition of heavy metals in water and bottom sediments mainly characterizes the natural geochemical background. The discharge of industrial wastewater leads to an increase of elements of anthropogenic origin in the composition of water and bottom sediments.

Effect of Microplastics on the Adsorption and Desorption Properties of Cadmium in Soil.

This study analyzed the role of micro polyethylene (mPE) and micro polypropylene (mPP) on cadmium (Cd) adsorption and desorption in soil. Cd adsorption in soils reached equilibrium within 240min with or without mPP/mPE. The largest Cd adsorption amount was 923.88mgkg-1 in the control treatment (no MPs). The Cd adsorption amount in the mPP treatment was 872.21mgkg-1, greater than that in the mPE treatment (780.21mgkg-1). MPs reduced the soil adsorption of Cd to some extent. Soils supplemented with mPE were more inhibitory to Cd adsorption than mPP. The pseudo-second-order model equation proved to be the most optimal equation for describing Cd adsorption dynamics in the presence of different MPs, while the Freundlich equation was best for describing isothermal adsorption of Cd in the presence of MPs. MPs facilitate the desorption of metals from the soil.

Adsorption and desorption of heavy metals at water sediment interface based on bayesian model

Estuarine areas are not only the main gathering point for human sewage but also the place where one-way and two-way fluids interact, thus forming a complex and changeable geochemical physical field. Here, heavy metals (HMs) are adsorbed and desorbed due to physical, chemical, and biochemical processes. However, the adsorption and desorption behavior of HMs in the aquatic environment is complex, and physicochemical processes occurring in the estuarine sediment-water interface control the direction and boundaries of the system. This study analyzed the migration and distribution of HMs in rivers and lakes, and established a Bayesian network model to quantitatively understand the impact of nutrients and key environmental factors on the adsorption-desorption behavior of HMs in lake and estuaries, as well as the competitive relationship between environmental factors. The influence of environmental factors and the occurrence of HMs are both important model inputs. Our findings indicated that the migration risk of Cd in Qinghai Lake was high. Environmental factors such as Cation exchange capacity (CEC), Organic matter (OM), Soluble fluoride (SFL), and pH play the most important role in the adsorption and desorption of HMs. Our findings also indicated that the exchange and activity of HMs in sediments were much higher than in the overlying water. The organic matter content was the most complex environmental factor affecting HMS adsorption and desorption at the water-sediment interface. Additionally, the mass concentration of dissolved oxygen (DO) has a linear relationship with bioavailable HMs in river and lake sediments, but has no linear relationship with the concentration of water-soluble HMs. Interestingly, there are synergistic effects between environmental factors, which directly or indirectly affect the release of bioavailable HMs. However, it is important to determine whether the effects of different environmental factors on the exchange of bioavailable HMs are negative or positive. Our findings suggested that Bayesian network (BN) signals (positive or negative) could provide insights into the transfer direction of metals in the water-sediment interface.

Ultra-sensitive detection of multiplexed heavy metal ions by MOF-derived carbon film encapsulating BiCu alloy nanoparticles in potable electrochemical sensing system

In this work, we report the development of a new type of highly active and stable Bi-based electrode material, i.e., BiCu metal-organic frames (MOF) derived carbon film (CF) encapsulating BiCu alloy nanoparticles (BiCu-ANPs) for electrochemical sensing. The integration of Bi with Cu to form BiCu-ANPs can improve their electrocatalytic activity as well as the acid resistance. Meanwhile, the carbon film that encapsulates BiCu-ANPs not only guarantees the BiCu-ANPs with high electrical conductivity and fast electrochemical kinetics but also effectively alleviates the volume change during the adsorption and desorption of heavy metal (HM) ions. Therefore, the as-obtained CF encapsulating BiCu-ANPs (BiCu-ANPs@CF) exhibits fully exposed active sites, facile charge transfer, high stability and conductivity, which gives rise to enhanced sensitivity and stability for the electrochemical detection of HM ions. When integrated into a potable electrochemical sensing system for simultaneous detection of Pb2+, Cd2+ and Zn2+, the BiCu-ANPs@CF modified electrode exhibits low detection limit (i.e., 0.081 ppb for Pb2+, 0.95 ppb for Cd2+, 35 ppb for Zn2+), wide detection range (i.e., 0.5–700 ppb for Pb2+, 5–900 ppb for Cd2+, 150–600 ppb for Zn2+) and good anti-interference. Finally, the system has been used for on-site detection of multiplexed HM ions in human biological liquids and environmental water with a good spiked recovery rate, which demanstrates its promise application in the future for on-site monitoring of human health and pollutants in water quality.

Removal of Pb2+, CrT, and Hg2+ Ions from Aqueous Solutions Using Amino-Functionalized Magnetic Nanoparticles.

In this paper, a circular economy approach with the adsorption and desorption of heavy metal (HM) ions-i.e., lead (Pb2+), chromium (CrT), and mercury (Hg2+)-from aqueous solutions was studied. Specific and selective binding of HM ions was performed on stabilized and amino-functionalized iron oxide magnetic nanoparticles (γ-Fe2O3@NH2 NPs) from an aqueous solution at pH 4 and 7. For this purpose, γ-Fe2O3@NH2 NPs were characterized by thermogravimetric analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), specific surface area (BET), transmission electron microscopy (TEM), EDXS, and zeta potential measurements (ζ). The effects of different adsorbent amounts (mads = 20/45/90 mg) and the type of anions (NO3-, Cl-, SO42-) on adsorption efficiency were also tested. The desorption was performed with 0.1 M HNO3. The results showed improvement of adsorption efficiency for CrT, Pb2+, and Hg2+ ions at pH 7 by 45 mg of g-Fe2O3@NH2 NPs, and the sequence was as follows: CrT > Hg2+ > Pb2+, with adsorption capacities of 90.4 mg/g, 85.6 mg/g, and 83.6 mg/g, respectively. The desorption results showed the possibility for the reuse of γ-Fe2O3@NH2 NPs with HNO3, as the desorption efficiency was 100% for Hg2+ ions, 96.7% for CrT, and 91.3% for Pb2+.

Enhancement of heavy metals desorption from the soil by eddy deep leaching in hydrocyclone

An eddy deep leaching technology was developed in this paper to address the challenge of treating heavy metal contaminants in industrial mining areas. The desorption effect of As, Cd, Sb and Pb was investigated utilizing chemical leaching and physical eddy techniques. It was found that the heavy metals concentration increased with decreasing particle size. The highest proportion of Cd in the form distribution of soil was in the bound to iron and manganese oxides, while the maximum proportion of As, Sb and Pb were in the residual. The optimal solid-liquid ratio of the hydrocyclone was 1:20, and the corresponding separation efficiency and flow rate were 84.7% and 1.76 m3/hr, respectively. The grade efficiency of soil particle separation increases with particle size and exceeds 99% for particles above 1,000 µm. Leaching experiments have revealed that oxalic acid (OA) and a combination of oxalic acid and EDTA (OAPE) were more efficient than citric acid (CA) and a combination of citric acid and EDTA (CAPE) for the desorption of heavy metals, respectively. The comparison of OAPE and eddy leaching found that the latter improved the desorption efficiency by 9.4%, 7.5%, 7.2% and 7.8% for As, Cd, Sb and Pb compared to the former, respectively. The results demonstrated that the eddy leaching technique could further enhance the desorption efficiency of heavy metals. It is expected to provide technical support for soil remediation with reduced usage of leaching agents.

Laser-based techniques: Novel tools for the identification and characterization of aged microplastics with developed biofilm

Microplastics found in the environment are often covered with a biofilm, which makes their analysis difficult. Therefore, the biofilm is usually removed before analysis, which may affect the microplastic particles or lead to their loss during the procedure. In this work, we used laser-based analytical techniques and evaluated their performance in detecting, characterizing, and classifying pristine and aged microplastics with a developed biofilm. Five types of microplastics from different polymers were selected (polyamide, polyethylene, polyethylene terephthalate, polypropylene, and polyvinyl chloride) and aged under controlled conditions in freshwater and wastewater. The development of biofilm and the changes in the properties of the microplastic were evaluated. The pristine and aged microplastics were characterized by standard methods (e.g., optical and scanning electron microscopy, and Raman spectroscopy), and then laser-induced breakdown spectroscopy (LIBS) and laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) were used. The results show that LIBS could identify different types of plastics regardless of the ageing and major biotic elements of the biofilm layer. LA-ICP-MS showed a high sensitivity to metals, which can be used as markers for various plastics. In addition, LA-ICP-MS can be employed in studies to monitor the adsorption and desorption (leaching) of metals during the ageing of microplastics. The use of these laser-based analytical techniques was found to be beneficial in the study of environmentally relevant microplastics.

Poly-condensation of N-(2-acetamido)-2-aminoethanesulfonic acid with formaldehyde for the synthesis of a highly efficient sorbent for Cs(I)

A new sorbent (ACES-F micro-particles) is readily synthesized by the one-pot reaction of N-(2-acetamido)-2-aminoethanesulfonic acid with formaldehyde (poly-condensation reaction). The mesoporous sorbent is characterized by BET analysis (SBET: ≈6 m2 g−1), SEM-EDX (N: ≈7–8 % and S: 5 %), FTIR spectroscopy (identification of amine, sulfonic groups and their interactions with metal ions), TGA, elemental analysis, and titration (pHPZC: ≈5.7). The study of pH effect on Cs(I) shows an optimum close to 8 (with intermediary optimum at pH 4, associated with different reactive groups). The micron-size sorbent shows fast sorption (equilibrium in 60 min) and the pseudo-first order rate equation fits the kinetic profile. The sorption isotherm reaches up to 1.99 mmol Cs g−1; the Langmuir equation models isotherm profiles. The sorption decreases with increasing temperature; sorption is exothermic. Cesium uptake is affected by the presence of NaCl; however, even in large excess of salt (i.e., 4 M) sorption remains relatively high (loss <60 %). Selectivity is confirmed by the remarkable preference of the sorbent for Cs against alkali and other competitor metal ions, especially at pHeq ≈7. Metal desorption is highly effective using 0.3 M HNO3 solutions: complete desorption occurs in 30 min. The sorbent can be recycled for at least five cycles (losses <3 %). The interest of ACES-F for cesium recovery from seawater is confirmed by the study of Cs(I) sorption (and other major elements) from Vietnam and Egypt samples. The safety of the sorbent for aqueous bodies is evaluated by the cytotoxicity of the sorbent (limited against normal cells but highly reactive for cancerous cells); while the sorbent shows interesting antimicrobial properties for Gram+, Gram- and pathogenic yeast.