Synthesis and application of restricted access material-ion imprinted poly(allylthiourea) for selective separation of Cd2+ and humic acid exclusion

In Situ Polymerization Strategy for Improving the Stability of Sn-Based Perovskite Solar Cells

Sn-based perovskite solar cells (Sn-PSCs) have received increasing attention due to their nontoxicity and potentially high efficiency. However, the poor stability of Sn2+ ions remains a major problem in achieving stable and efficient Sn-PSCs. Herein, an in situ polymerization strategy using allyl thiourea and ethylene glycol dimethacrylate as cross-linking agents in the Sn-based perovskite precursor is proposed to improve the device performance of Sn-PSCs. The C═S and N-H bonds of the cross-linkers are able to coordinate with SnI2 and inhibit the oxidation of Sn2+, thereby reducing defect density and improving the stability of Sn-based perovskite films. The high quality of the perovskite film induced by the in situ polymerization strategy delivers an improved power conversion efficiency (PCE) from 7.50 to 9.22%. More importantly, the unpackaged device with cross-linkers maintained more than 70% of the initial PCE after 150 h of AM 1.5G light soaking in a nitrogen atmosphere and 80% of the initial PCE after 1800 h in dark conditions. This work demonstrates that the in situ polymerization strategy is an effective method to enhance the stability of Sn-based perovskite films and devices.

Restricted double access ionic imprinted polymer for online extraction and determination of copper from milk samples via FIA-FAAS system

BACKGROUND

Determining metals in complex biological samples, such as milk, typically involves dry or wet decomposition. However, these techniques have limitations, including low selectivity, risk of contamination, and the use of large reagent volumes. To solve these problems, solid-phase extraction (SPE) using multifunctional sorbents has been extensively explored. In this context, this work proposed synthesizing a new restricted double access ionic imprinted polymer (RAIIP-BSA), for online SPE and determination of Cu2+ from untreated milk samples via flow injection analysis and flame atomic absorption spectrometry (FIA-FASS).

RESULTS

Firstly, the polymer was obtained by bulk polymerization using Cu2+ as a template, 4-vinyl pyridine as a functional monomer, and glycidyl methacrylate as a hydrophilic comonomer. Subsequently, it was covered with bovine serum albumin, creating the restricted double access barrier. The obtained material could exclude 97 % of the proteins from milk samples. RAIIP-BSA was chemically and physically characterized. The main extraction variables were optimized via multivariate optimization. The method showed good figures of merit, such as linearity ranging from 0.05 to 1.0 mg L-1, LoD and LoQ of 0.03 and 0.05 mg L-1, intra- and interday precision ranging from 0.73 to 4.14 % and 0.16-3.68 %, and an intra- and interday accuracy ranging from 97.0 to 115.0 % and 103.0-119.0 %, respectively.

SIGNIFICANCE

The developed method demonstrates the effective extraction of Cu2+ from untreated milk samples, exhibiting selectivity, high extraction capacity, prolonged sorbent (RAIIP-BSA) durability, simplicity, and swift operation. This method holds promise as an alternative to conventional metal analysis approaches in complex matrices.

Construction of 1, 10-phenanthroline functionalized magnetic starch as a lead (II) tagged surface imprinted biopolymer for highly selective targeting of toxic lead ions

In this research 1, 10 - phenanthroline functionalized CaFe₂O₄ - starch was employed as a magnetic ion-imprinted polymer (IIP) for highly selective targeting toxic Pb²⁺ ions from aqueous media. VSM analysis revealed that the sorbent has magnetic saturation of 10 emu g^-1 which is appropriate for magnetic separation. Moreover, TEM analysis confirmed that the adsorbent is composed of particles with a mean diameter of 10 nm. According to XPS analysis, lead coordination with phenanthroline is the main adsorption mechanism that is along with electrostatic interaction. A maximum adsorption capacity of 120 mg g^-1 was obtained within 10 min at a pH of 6 and an adsorbent dosage of 20 mg. Kinetic and isotherm studies showed that lead adsorption followed the pseudo-second-order and Freundlich models, respectively. The selectivity coefficient of Pb (II) relative to Cu(II), Co(II), Ni(II), Zn(II), Mn(II), and Cd(II) was 4.7, 14, 20, 36, 13 and 25, respectively. Moreover, the IIP represents the imprinting factor of 1.32. The sorbent showed good regeneration after five cycles of the sorption/desorption process with an efficiency of >93 %. Finally represented IIP was used for lead preconcentration from various matrices i.e., water, vegetable, and fish samples.

A facile approach for grafting ion imprinted polymer onto magnetic multi-walled carbon nanotubes for selective removal and preconcentration of cadmium in food and wastewater samples prior to atomic spectrometric determination

A 3D Fe₃O₄@MWCNT-CdIIP was synthesized by the oxidizing surface of multi-walled carbon nanotubes with carboxylic acid end groups and its subsequent termination with an ion imprinted polymer. An artificial neural network manifests better predictability than the central composite design methodology for optimising the adsorption procedure. The adsorption capacity was 109 mg g^-1 (2.5 times more than non-imprinted polymer) under optimized conditions (pH; 5.6, time; 15 min, concentration; 800 μg mL^-1 temperature; 25 °C), which was in accord with Toth isotherm. Fractal-like pseudo-second-order kinetics was found reasonably fast, with 66 % adsorption in 5 min. Solid phase extraction coupled Flame atomic absorption spectrometry method provides selective recognition towards Cd(II), with limit of detection; 1.13 µg/L, limit of quantification; 3.21 µg/L after preconcentration (preconcentration factor; 50) and good robustness. The developed method was applied for Cd(II) determination in food (tea, coffee, bread, tobacco, radish, spinach), water and wastewater (>99 % removal as well). Cd(II) loaded IIP was further utilized to remove anionic dyes with >95 % removal.

Investigation of the performance of cross-linked poly(acrylic acid) and poly(methacrylic acid) as efficient adsorbents in SPE columns for simultaneous preconcentration of tricyclic antidepressants in water samples

A solid phase extraction-based (SPE) procedure for simultaneous preconcentration of five tricyclic antidepressants (TCAs), amitriptyline hydrochloride (AMT), nortriptyline hydrochloride (NOR), doxepin hydrochloride (DOX), imipramine hydrochloride (IMI), and clomipramine hydrochloride (CLO) from water samples with determination by HPLC-DAD is proposed. Polymers were characterized by FT-IR, SEM, and thermogravimetric analysis. SPE-based methods were carried out by the preconcentration of 320.0 mL of TCAs at pH 7.0 (buffered with 0.01 mol L^-1 phosphate buffer) through 70.0 mg of adsorbent packed into a SPE cartridge, followed by elution with 1.0 mL of ACN : MeOH : acetic acid solution (45 : 45 : 10% v/v). Higher preconcentration factors were obtained ranging from 117.9 to 372.2 and 207.1 to 396.1 by using poly(MAA-co-EGDMA) and poly(AA-co-EGDMA), respectively, yielding lower limits of detection (0.03 to 0.12 μg L^-1) and (0.03 to 0.15 μg L^-1). These outcomes show satisfactory detectability of SPE-based methods, with slightly better performance using poly(MAA-co-EGDMA). On the other hand, poly(AA-co-EGDMA) was able to preconcentrate TCAs in the presence of humic acid (7.0 mg L^-1) without interference. The precision of methods assessed as RSD (%) was very similar, ranging from 1.7% to 16.3% for poly(MAA-co-EGDMA) and 1.7% to 13.4% for poly(AA-co-EGDMA). SPE cartridges packed with the polymers showed high reusability (52 cycles of preconcentration and elution) without losing adsorption efficiency. The methods were applied to determine TCAs in tap, lake, and stream water samples and the accuracy was attested by addition and recovery tests (86.7-116.0%), with determined nortriptyline ranging from 0.48 to 0.52 μg L^-1 in lake water samples.