Silanized fiberglass modified by carbon dots as novel and impressive adsorbent for aqueous heavy metal ion removal.

This work discusses the application of a silanized fiberglass (SFG) modified by carbon dots (CDs) as an effective adsorbent for up-taking some heavy metal ions including lead (Pb2+), chromium (Cr3+), cadmium (Cd2+), cobalt (Co2+), and nickel (Ni2+) as pollutant in the aqueous solution by batch method. Removal tests were carried out after optimization of pH, contact time, initial concentration of metal ions, and CDs amount. The SFG modified with CDs (CDs-SFG) was applied for the removal of 10 ppm of each metal ion solution after 100 min and the corresponding results showed the removal efficiencies of 100, 93.2, 91.8, 90, and 88.3% for Pb2+, Cd2+, Cr3+, Co2+, and Ni2+, respectively. The adsorption capacity of CDs-SFG in the metal ion mixed solution was also evaluated, and the results indicated the same trend in the adsorption capacity for metal ions in the mixed solution, though with lower absolute values compared to the single metal solutions. Moreover, the selectivity of this adsorbent for the adsorption of Pb2+ was almost twice of other tested metal ions. The regeneration of the CDs-SFG showed that its adsorption capacity after five cycles was reduced about 3.9, 6.0, 6.8, 6.7, and 8.0% for Pb2+, Cd2+, Cr3+, Co2+, and Ni2+, respectively. Finally, the applicability of the CDs-SFG adsorbent was examined with the analysis of the metal ions in water and wastewater samples.

Trace determination of triazine herbicides in fruit and vegetables using novel hydrophobic deep eutectic solvent-based dispersive liquid-liquid microextraction followed by high-performance liquid chromatography-ultraviolet.

In the present research, a novel hydrophobic deep eutectic solvent-based dispersive liquid-liquid microextraction technique was established and combined with high-performance liquid chromatography-ultraviolet for the determination of triazine herbicides in fruit and vegetable samples. A deep eutectic solvent was synthesized using l-menthol as a hydrogen bond acceptor and ethylene glycol as a hydrogen bond donor and used as a green extractant. The characterization of deep eutectic solvent was investigated by Fourier-transform infrared, nuclear magnetic resonance, and thermogravimetric analysis. Under the optimum conditions, relative standard deviation values for intra-day and inter-day of the method based on seven replicate measurements of 50.0 µg/kg of triazines were in the range of 2.8%-5.5% and 3.7%-7.2%, respectively. The calibration graphs were linear in the range of 3.0-500 µg/kg and the limits of detection were in the range of 1.0-2.0 µg/kg. The relative recoveries of different fruit and vegetable samples that have been spiked with two levels of target compounds were 91.5%-109.8%. The method has good linearity, sensitivity, accuracy, and precision. It is also environmentally friendly and was successfully used to determine the concentrations of triazines in fruit and vegetable samples.

Novel deep eutectic solvent-based liquid phase microextraction for the extraction of estrogenic compounds from environmental samples.

Steroid hormones, such as estrone (E1), 17ß-estradiol (E2), 17ß-ethinylestradiol (EE2) and estriol (E3) are a group of lipophilic active substances, synthesized biologically from cholesterol or chemically. A pH-switchable hydrophobic deep eutectic solvent-based liquid phase microextraction (DES-LPME) technique was established and combined with gas chromatography-mass spectroscopy for the determination of estrogenic compounds in environmental water and wastewater samples. A DES was synthesized using l-menthol as HBA and (1S)-(+)-camphor-10-sulfonic acid (CSA) as HBD, and used as a green extraction solvent. By adjusting the pH of the solution, the unique behavior of the DES in the phase transition and extraction of the desired analytes was investigated. The homogenization process of the mixture is done only by manual shaking in less than 30 seconds and the phase separation is done only by changing the pH and without centrifugation. Some effective parameters on the extraction and derivatization, such as molar ratio of DES components, DES volume, KOH concentration, HCl volume, salt addition, extraction and derivatization time and derivatization prior or after extraction were studied and optimized. Under the optimum conditions, relative standard deviation (RSD) values for intra-day and inter-day of the method based on 7 replicate measurements of 20 ng L-1 of estrogenic compounds and 10 ng L-1 for internal standard in different samples were in the range of 2.2-4.6% and 3.9-5.7%, respectively. The calibration graphs were linear in the range of 0.5-100 ng L-1 and the limits of detection (LODs) were in the range of 0.2-1.0 ng L-1. The relative recoveries of environmental water and wastewater samples which have been spiked with different levels of target compounds were 91.0-108.8%.

A highly selective green supported liquid membrane by using a hydrophobic deep eutectic solvent for carrier-less transport of silver ions.

A new supported liquid membrane (SLM) was designed by using a suitable deep eutectic solvent (DES) as the hydrophobic liquid membrane phase for the selective and facilitated carrier-less transport of Ag+ ions. The deep eutectic solvent was composed of a 4/1 molar ratio of l-menthol/salicylic acid and was impregnated into a microporous polypropylene membrane to prepare a novel carrier-less SLM system. The highly selective facilitated transport of silver ions was accomplished by using sodium thiosulfate as a highly selective stripping agent for Ag+ ions in the aqueous strip phase (SP). Some important factors, including the concentration of picric acid in the feed phase (FP), pH of the two aqueous phases, stirring rate, transport time, and nature and concentration of the stripping agent were also investigated and optimized. In the presence of 2.8 × 10-2 mol L-1 picrate ions as an appropriate ion pairing agent in the FP and 0.025 mol L-1 thiosulfate as a convenient metal ion acceptor in the SP, the amount of Ag+ ion transport found to occur almost quantitatively after 60 min is 90%. Compared with other SLM systems reported in the literature, the designed DES-SLM system exhibited suitable permeability and higher selectivity for Ag+ ion transport from aqueous solutions containing Fe2+, Mn2+, Cu2+, Ni2+, Pb2+, and Cd2+ as competing metal ions.