Carbon xerogels combined with nanotubes as solid-phase extraction sorbent to determine metaflumizone and seven other surface and drinking water micropollutants

Occurrence of micropollutants in surface waters: Monitoring of Portuguese Lima and Douro River estuaries and interconnecting northwest coast

This study monitored the occurrence of 34 MPs in 2 Portuguese estuaries and adjacent coastal area using solid-phase extraction and liquid chromatography-tandem mass spectrometry, covering: (i) an extensive monitoring study area; (ii) a multi-class group of organic MPs, including some outlined in European Union guidelines for water protection; (iii) a year-long monitoring campaign including different seasons; (iv) samples collected at both flood and ebb tide; and (v) samples taken from the water surface and bottom at each sampling point. Results showed that a specific group of compounds prevailed in the monitored areas, with concentrations depending on season, tide, and location. In general, the MPs found more frequently were isoproturon and perfluorooctanesulfonic acid, along with pharmaceuticals trimethoprim, acetaminophen, tramadol, diclofenac, and ketoprofen, which were mostly detected at higher concentrations. Although most MPs have been detected at very low levels, their persistent and widespread presence highlights the need for mitigation measures and effective water treatment solutions able to address them.

Composite hydrogel based on alginate-g-poly(acrylamide)/carbon nanotubes for solid phase extraction of metals from corn cereal samples

Composite hydrogels containing nanofillers are extensively applied in the sorption of different compounds from aqueous solutions; however, this ability is poorly exploited in the extraction and pre-concentration of analytes from complex matrices. As a contribution to this field, this study reports the synthesis of a composite hydrogel of alginate-g-poly(acrylamide) matrix filled with functionalized multi-walled carbon nanotubes (ALG-g-PAAM/MWCNT-f). This composite served as a solid-phase extractor (SPE) for the separation of Pb²⁺ and Cd²⁺ ions from a digested corn cereal sample before their analytical determination. After composite characterization, a series of experiments using low dosages of ALG-g-PAAM/MWCNT-f demonstrated that the composite has a higher sorption capacity for Pb²⁺ (5.1 mg/g) and Cd²⁺ (3.9 mg/g) under favorable experimental conditions. As demonstrated, the presence of the MWCNT-f benefited the SPE performance of the composite. The sorption of both cations followed the pseudo-first order kinetics, while the experimental data were well-fitted by the Freundlich isotherm. Also, ALG-g-PAAM/MWCNT-f showed selectivity for Pb²⁺, and it is reusable up to 10 times without losing sorption performance. After sorption and extraction, both metals were completely recovered, facilitating their quantification by the MIP OES technique. In short, ALG-g-PAAM/MWCNT-f was an effective SPE for the separation and extraction of Pb²⁺ and Cd²⁺, which can be beneficial for food control and safety.