Search

Water contamination with various kinds of pollutants is a global challenge. Heavy metal contamination causes several health and environmental issues. Several technologies have been developed for the removal of heavy metals from water. The adsorption is advantageous because of its high efficiency, simple operation, and relatively low cost. Natural sorbents are preferable over synthetic sorbents because of the toxicity concerns and leaching issues during the adsorption process. The plant-derived sorbents are easily available, renewable, biodegradable, and in most cases, non-toxic compared to synthetic sorbents. They can present a viable solution for water treatment in low-resource setups. In this work, Conocarpus lancifolius leaves were employed as sorbent for the simultaneous removal of cadmium, chromium, and lead ions from aqueous samples. The sorbent was prepared simply by washing, drying, and grinding the leaves of C. lancifolius and did not involve the use of chemicals and solvents. The sorbent was characterized by Fourier-transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, energy-dispersive X-ray, and X-ray diffraction. The characterization revealed the presence of several functional groups and relatively a rough and porous morphology. The effect of various parameters such as pH, sorbent dosage, contact time, and adsorbate concentration on the percentage removal of metals was investigated. The best results for simultaneous removal were obtained at pH 6, a sorbent dosage of 300 mg, and a contact time of 45 min. It also showed good performance in a column study, and it was capable of completely removing both low- (100 µg/L) and high-level (10 mg/L) concentrations of the metals. The sorbent also showed good reusability potential. [ABSTRACT FROM AUTHOR]

In the study, an adsorptive removal strategy as a straightforward and fast procedure was developed to remove four aflatoxins, including aflatoxin B1 (AF-B1), aflatoxin B2 (AF-B2), aflatoxin G1 (AF-G1), and aflatoxin G2 (AF-G2). A simple and green sorbent consisting of two components (activated nanobentonite and Fe3O4 nanoparticles) was synthesized based on three steps using acidic treatment, ultrasonic procedure, and chemical precipitation method. The sorbent was characterized by several techniques such as FTIR, FESEM, TEM, XRD, and VSM to determine the sorbent structure and morphology. An experimental design based on a central composite design was utilized to optimize factors in the removal of AFs. The optimum values of the factors (pH, sorbent amount, shaking rate) were 6.8, 0.076 g, and 160 rpm, respectively. Three models, including pseudo-first-order, pseudo-second-order, and intra-particle diffusion models, were used to investigate the kinetics of the removal process. The removal of AFs using magnetic nanobentonite was fitted with the pseudo-second-order model better than other models with an equilibrium time lower than 30 min. The thermodynamic data show that the adsorption of AFs on the sorbent is a spontaneous and feasible process due to negative values of the Gibbs-free energy change (ΔG) at different temperatures. Two models (Langmuir and Freundlich models) were chosen to study the isotherm of the removal procedure, indicating that the Freundlich model describes the results better than the Langmuir model. The maximum adsorption capacity of the sorbent for removing AF-B1, AF-B2, AF-G1, and AF-G2 is 357.14, 400.0, 370.37, and 400.0 mg g−1, respectively. The sorbent reusability was also evaluated to study the sorbent's ability for the removal of AFs, indicating that the sorbent was used for 5 cycles without a significant reduction in the ability to remove AFs. [ABSTRACT FROM AUTHOR]

In response to growing concerns about environmental degradation, one of the main areas of research activity in recent years has been to make sample preparation methods more sustainable and eco-friendly. The increasing greenness of this step can be achieved by minimizing the usage of reagents, automating individual stages, saving energy and time, and using non-toxic, biodegradable substances. Therefore, the use of natural materials as sorbents in miniaturized extraction techniques is becoming a main trend. One of the natural material that is increasingly being used, not only due to eco-friendly nature but also because of their easy applicability to various sample preparation techniques, is alginate hydrogel. Following this trend, this review discusses the recent application of alginate-based sorbents in various microextraction techniques, focusing on functionalization approaches that enhance extraction performance. Additionally, the green profile of alginate-based sorbent microextraction approaches, along with the sorbent synthesis, were investigated. [Display omitted] • Alginate-based sorbents serve as an effective sorptive material in microextraction. • Compounding alginate gel with other sorbents to improve sorption performance. • Alginate-based sorbent synthesis are not as green as desirable. [ABSTRACT FROM AUTHOR]

The present study reports the synthesis of a green sorbent using Araucaria heterophylla resin coated on magnetic nanoparticles for the efficient abatement of herbicides; Mesotrione and Metsulfuron methyl from aqueous solution. Characterisation of the sorbent was done by Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) that confirmed coated nanoparticles as small agglomerates containing various functional groups. Optimisation of pH, initial concentration and contact time were performed to achieve maximum adsorption. In addition to this, Freundlich and Langmuir isotherm models have been applied to study the adsorption behaviour of these herbicides. Maximum percentage removal of 92% and 88% for Mesotrioneand metsulfuron methyl was obtained respectively. Adsorption process followed Langmuir isotherm and qmax of 18.3 mg/g (Mesotrione) and 9.3 mg/g (metsulfuron) were found. The synthesised nanoparticlesare biocompatible, cost effective and can be regenerated for multiple cycles of adsorption. [ABSTRACT FROM AUTHOR]

The present study aims at the development of a green sorbent (MgAl-LDH-biochar) from the municipal solid wastes (cow bones) to remediate water from heavy metals. MgAl-LDH-biochar was characterized using X-ray diffraction (XRD), and it was used to remove lead at different pH, doses, contact time (Ct), and solution temperatures (St). The obtained results proved MgAl-LDH-biochar removes 99% of lead when the initial pH, Ct, St, and dose were 5.0, 80 min, 45°C, and 0.2 g·L–1, respectively.

A film composed of agarose and graphene (G) and magnetic nanoparticles (G-MNPs) is proposed as a sorbent for the extraction and determination of medroxyprogesterone (MED), levonorgestrel (LEV), norethisterone (NOR) and progesterone (PRO) in natural water samples. Both the preparation of the film and the extraction procedure were optimized. The optimal extraction parameters were as follows: isopropyl alcohol as activation solvent, sample pH value of 3.0, extraction time of 30 min, 1.00 mL of acetonitrile as eluent, elution time of 5 min and sample volume of 100.00 mL. HPLC with photodiode array detector was used for the separation and determination. The method presented a linear range between 2.50 and 75.0 μg L−1 for all analytes, and the LODs were between 1.40 and 1.80 μg L−1. The method was applied to natural water samples, obtaining satisfactory recovery values (75–111 %). In conclusion, for the immobilization of the G-MNPs, agarose was used, which is a non-toxic, renewable and biodegradable material. The G-MNPs-agarose film was reused up to 70 times, without losing its extraction capacity significantly and presenting excellent sorbent properties, which allow the extraction and preconcentration of the progestogens under study. [Display omitted] • A single, reusable and biodegradable G-MNPs-agarose film was prepared for progestogens extraction. • The film presented excellent mechanical properties and high extraction efficiency. • The film was reusable for 70 times without losing its extraction capacity. [ABSTRACT FROM AUTHOR]

Herein, for the determination of trace amounts of five petroleum pollutants (TLU, OCT, p-XY, o-XY and AN) in the water samples with complex matrices, first of all, the glass fibers sheet was applicated as a supporting substrate and then the GLA/SO/FS/Ag NPs/AC electrospun nanofibers was prepared (17 kV, 12 cm, 2 μL min−1) on this substrate. Subsequently, the photo crosslinking was accomplished at λ= 366 nm. In the next step, these nanofibers were used as a sorbent under the spin column-micro solid phase extraction (SC-μSPE) of five petroleum pollutants in the sea water, farm water and drinking water samples under obtained optimum conditions with design expert software and on at a time (OAT) method. [Display omitted] • The electrospun nanofibers (GLA/SO/FS/Ag NPs/AC) were used as a sorbent in SC-μSPE. • The preconcentrated solution of five petroleum pollutants was injected into GC-FID. • The optimization step was accomplished with both the design expert and OAT. • The amounts of 5 petroleum pollutants were determined in the various water samples. Herein, green electrospun nanofibers were prepared based on gelatin/soybean oil/fumed silica/Ag NPs/activated carbon (GLA/SO/FS/Ag NPs/AC). Then, the nanofibers were used as an efficacious sorbent in the spin-column-micro solid-phase extraction (SC-µSPE) of trace amounts of five petroleum pollutants (toluene, n-octane, p-xylene, o-xylene, and aniline). The mentioned pollutants were measured in various water samples using GC-FID. GLA/SO/Ag NPs/FS/AC electrospun nanofibers were characterized using field emission-scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy with elemental mapping analysis (EDX-Mapping), Brunauer-Emmett-Teller (BET) surface analysis, Fourier transform-infrared (FT-IR), and X-ray diffraction (XRD), confirming the synthesis of the composite nanofibers. Factors affecting the adsorption and desorption process of SC-µSPE were optimized using design-expert 12.0 software and the one-at-a-time method. A wide linear range of 3–1100 ng mL−1 with R2 ≥ 0.9883 was achieved under the optimum conditions, along with low detection limits ranging from 1.08 to 6.8 ng mL−1 based on S/N = 3 and significant enrichment factors. Intra-day and inter-day RSDs% ranged from 4.23 % to 5.77 % and 5.72 % to 7.39 %, respectively. Lastly, the efficiency of the SC-µSPE method was evaluated to determine these five petroleum pollutants in various water samples, yielding good recoveries ranging from 94.2 % to 102.6 %. [ABSTRACT FROM AUTHOR]

The present study aims at the development of a green sorbent (MgAl-LDH-biochar) from the municipal solid wastes (cow bones) to remediate water from heavy metals. MgAl- -LDH-biochar was characterized using X-ray diffraction (XRD), and it was used to remove lead at different pH, doses, contact time (Ct), and solution temperatures (St). The obtained results proved MgAl-LDH-biochar removes 99% of lead when the initial pH, Ct, St, and dose were 5.0, 80 min, 45°C, and 0.2 g·L–1, respectively. [ABSTRACT FROM AUTHOR]

In the present study, a simple, fast, and economical method was introduced to eliminate methylene blue from dye wastewater water using a non-toxic, inexpensive, stable, and efficient adsorbent. The poly (vinyl alcohol) (PVA)/starch hydrogel nanofiber membrane with high surface area and the three-dimensional structure was fabricated in water via electrospinning strategy, and the cross-linking reaction was done by thermal treatment. The characterization of the nanofibers was carried out using Fourier-transform infrared spectrometer (FT-IR) and field-emission scanning electron microscopy (FE-SEM), and the cross-linked PVA/starch nanofiber was applied as a membrane for the removal of methylene blue (MB). The recovery of MB was performed by methanol solution containing 5% (v/v) HCl. Langmuir isotherm model successfully described the adsorption of MB on nanosorbent, and the maximum adsorption capacity (qm) was 400 mg g−1. Also, the kinetic of adsorption was well fitted by the pseudo-second-order model. In this study, because of the high stability of fabricated membrane (based on the tensile testing), it can be used as a filter for the fast separation of MB (cationic dye) and methyl orange (MO, anionic dye). [ABSTRACT FROM AUTHOR]

Bio-calcite (BC) derived from waste hen eggshell was subjected to thermal treatments (calcined bio-calcite (CBC)). The BC and CBC were further modified via magnesiothermal treatments to produce modified bio-calcite (MBC) and modified calcined bio-calcite (MCBC), respectively, and evaluated as a novel green sorbent for P removal from aqueous solutions in the batch experiments. Modified BC exhibited improved structural and chemical properties, such as porosity, surface area, thermal stability, mineralogy and functional groups, than pristine material. Langmuir and Freundlich models well described the P sorption onto both thermally and magnesiothermally sorbents, respectively, suggesting mono- and multi-layer sorption. Langmuir predicted highest P sorption capacities were in the order of: MCBC (43.33 mg g−1) > MBC (35.63 mg g−1) > CBC (34.38 mg g−1) > BC (30.68 mg g−1). The MBC and MCBC removed 100% P up to 50 mg P L−1, which reduced to 35.43 and 39.96%, respectively, when P concentration was increased up to 1000 mg L−1. Dynamics of P sorption was well explained by the pseudo-second-order rate equation, with the highest sorption rate of 4.32 mg g−1 min−1 for the MCBC. Hydroxylapatite [Ca10(PO4)6(OH)2] and brushite CaH(PO4)·2H2O] were detected after P sorption onto the modified sorbents by X-ray diffraction analysis, suggesting chemisorption as the operating sorption mechanism. [ABSTRACT FROM AUTHOR]

Calcium alginate (CA) beads as a green sorbent were easily fabricated in this study using sodium alginate crosslinking with CaCl2, and the crosslinking pathway was the exchange between the sodium ion of α-L-guluronic acid and Ca(II). The experimental study was conducted on Cu(II), Cd(II), Ni(II) and Zn(II) as the model heavy metals and the concentration was determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The characterization and sorption behavior of the CA beads were analyzed in detail via using scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The adsorption experiments demonstrated that the CA beads exhibited a high removal efficiency for the selective adsorption of Cu(II) from the tetra metallic mixture solution and an excellent adsorption capacity of the heavy metals separately. According to the isotherm studies, the maximum uptake of Cu(II) could reach 107.53 mg/g, which was significantly higher than the other three heavy metal ions in the tetra metallic mixture solution. Additionally, after five cycles of adsorption and desorption, the uptake rate of Cu(II) on CA beads was maintained at 92%. According to the properties mentioned above, this material was assumed to be applied to reduce heavy metal pollution or recover valuable metals from waste water.

Chitin is considered to be the second most abundant naturally-occurring polysaccharide. Also, dimethyl sulfoxide (DMSO) is the second highest dielectric constant polar solvent after water. Despite the low solubility of chitin in common organic solvents, and due to its high nitrogen content, it may serve as a potential scrubbing agent “wet scrubbing” for carbon dioxide (CO 2 ) capturing as an alternative to monoethanolamine “ renewables for renewables approach” . Briefly, a detailed investigation for the utilization of low molecular weight, chitin-acetate (CA) in DMSO for the capturing of CO 2 is reported. As carbonation process takes place, the formation of ionic alkylcarbonate was confirmed throughout spectroscopic and computational studies. Supramolecular chemisorption was proven throughout 1 H Nuclear Magnetic Resonance ( 1 H NMR) together with the absence of sorption of CO 2 by the monomeric repeating unit, glucosamine hydrochloride. Further, Density Functional Theory (DFT) calculations supported the formation of the CA/CO 2 adduct through a newly formed supramolecular ionic interaction and hydrogen bonding along the oligosaccharide backbone between the neighboring ammonium ion and hydroxyl functional groups. The sorption capacity was measured volumetrically within an in situ Attenuated Total Reflectance-Fourier Transform Infrared coupled ( in situ ATR-FTIR) autoclave at 25.0 °C, and 4.0 bar CO 2 , with a maximum sorption capacity of 3.63 mmol CO 2 /g sorbent at 10.0% (w/v). [ABSTRACT FROM AUTHOR]

A new series of [ n]-oligoureas ( [ n]-OUs, n= 4, 7, 10, and 12) green solid sorbents was prepared following a base-catalyzed, microwave-assisted oligomerization reaction. The materials were characterized by NMR and IR spectroscopy, elemental analysis, thermogravimetric analysis, differential scanning calorimetry, and XRD. Decomposition temperatures at 50 % weight loss ( Td50) were ca. 350 °C for all oligomers. Urea and urethane functional groups indicated by IR spectroscopy confirmed the formation of the sorbent. The CO2 capturing capacities were determined at 35 °C and 1.0 bar (gravimetric method). Accordingly, [10]-OU had the highest CO2 sorption capacity among the others (18.90 and 22.70 mg [ABSTRACT FROM AUTHOR]

Herein, we report the development and characterization of a green sorbent material. For the said purpose, the chitosan's capacity of cation sorption was enhanced by incorporating thiocarabamate group, which ultimately increases active sites for attracting the cationic species. The process was carried out by utilizing acrylomorpholine, carbon disulfide and chitosan in a single stage process. The product (CH-ATC) acquired was well characterized with 13C NMR (solid-form), FTIR spectroscopy, elemental investigation, thermogravimetic analysis and scanning electron microscopy. The novel product's ability of sorption was evaluated by applying it to lead and copper solution. The modified chitosan (CH-ATC) exhibited greater sorption capacity of lead (1.58 mmol g−1) over raw chitosan when applied to aqueous solution based on Langmuir sorption isotherm. The new material also showed reasonable sorption capacity for copper (1.25 mmol g−1). The experimentally obtained results associated well to Langmuir model than Temkin and Freundlich isotherms using linear regression method. Different linearization of Langmuir model showed different error functions and isothermal parameters. The nonlinear regression analysis showed lower values of error functions as compared to linear regression analysis. The chitosan with thiocarbamate chain is outstanding material for selected cations decontamination form aqueous solution. [ABSTRACT FROM AUTHOR]

• For the first time the use of cork by-products CBPs is proposed for fungicide extraction. • The most critical parameters affecting SPE were optimized by experimental design. • The proposed method was validated for 17 common use fungicides in environmental water. • Water samples collected in vineyards revealed the presence of fungicides at µg L−1. • CBPs is an efficient low-cost, green, ecofriendly alternative for fungicide analysis. During stoppers production, large amounts of cork by-products (CBPs) are generated, being used as low-value material. This project aims to turn CBPs into smart, natural and sustainable materials (sorbent) for solid-phase extraction (SPE) of pesticides from water. The study describes the use of CBPs for the extraction of 17 fungicides (metalaxyl, cyprodinil, tolylfluanid, procymidone, folpet, fludioxonil, myclobutanil, kresoxim methyl, iprovalicarb, benalaxyl, trifloxystrobin, fenhexamid, tebuconazole, iprodione, pyraclostrobin, azoxystrobin and dimethomorph) followed by gas chromatography-tandem mass spectrometry (GC-MS/MS) analysis. The most critical parameters affecting SPE were optimized by experimental design methodology. Under the optimal conditions, the method was successfully validated in terms of linearity, repeatability, and intermediate precision. Fungicide recovery was assessed in different real water samples including river, fountain, rainwater and spring water at 3 concentration levels (0.1, 0.5 and 10 µg L−1). Recoveries ranged between 70-118% with RSD values lower than 20%, and matrix effects were not observed. Finally, the method was applied to samples from irrigation, rain, and river water, all collected in vineyards areas, revealing the presence of 10 of the 17 fungicides, at concentration up to hundreds of µg L−1. The use of CBPs seems to be a promising low-cost and ecofriendly alternative to be employed as sorbent in SPE techniques to extract fungicides from the aquatic environment. [ABSTRACT FROM AUTHOR]

Calcium alginate (CA) beads as a green sorbent were easily fabricated in this study using sodium alginate crosslinking with CaCl2, and the crosslinking pathway was the exchange between the sodium ion of α-L-guluronic acid and Ca(II). The experimental study was conducted on Cu(II), Cd(II), Ni(II) and Zn(II) as the model heavy metals and the concentration was determined by inductively coupled plasma optical emission spectrometry (ICP-OES). The characterization and sorption behavior of the CA beads were analyzed in detail via using scanning electron microscopy (SEM), fourier transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS). The adsorption experiments demonstrated that the CA beads exhibited a high removal efficiency for the selective adsorption of Cu(II) from the tetra metallic mixture solution and an excellent adsorption capacity of the heavy metals separately. According to the isotherm studies, the maximum uptake of Cu(II) could reach 107.53 mg/g, which was significantly higher than the other three heavy metal ions in the tetra metallic mixture solution. Additionally, after five cycles of adsorption and desorption, the uptake rate of Cu(II) on CA beads was maintained at 92%. According to the properties mentioned above, this material was assumed to be applied to reduce heavy metal pollution or recover valuable metals from waste water. [ABSTRACT FROM AUTHOR]

A new series of [n]-oligoureas ([n]-OUs, n=4, 7, 10, and 12) green solid sorbents was prepared following a base-catalyzed, microwave-assisted oligomerization reaction. The materials were characterized by NMR and IR spectroscopy, elemental analysis, thermogravimetric analysis, differential scanning calorimetry, and XRD. Decomposition temperatures at 50 % weight loss (Td50 ) were ca. 350 °C for all oligomers. Urea and urethane functional groups indicated by IR spectroscopy confirmed the formation of the sorbent. The CO2 capturing capacities were determined at 35 °C and 1.0 bar (gravimetric method). Accordingly, [10]-OU had the highest CO2 sorption capacity among the others (18.90 and 22.70 mg CO 2 gsorbent (-1) ) at two different activation temperatures (60 or 100 °C, respectively). Chemisorption was the principal mechanism for CO2 capture. Cyclic CO2 sorption/desorption measurements were carried out to test the recyclability of [10]-OU. Activating the sample at 60 °C, three stable CO2 sorption cycles were achieved after running the first cycle., (© 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.)