Cellulose fibre (CF) has been widely employed as an adsorbent because of its effective capacity for adsorbing toxic components of cigarette smoke. There is a lack of studies of CF adsorbing ...pharmaceuticals from water. Herein, we evaluated the adsorption of potassium diclofenac (PD) from an aqueous medium by CF. In addition, we developed and prepared CF covered with polypyrrole (PPy) to improve the adsorptive capacity for removal of PD. From the infrared characterization, the main bands related to the functional groups of each component, PPy and CF, were identified; in thermogravimetry it was observed that both the CF and composite support relatively high temperatures and in the scanning electron microscopy it was possible to observe that the composite has a fibrous structure related to CF in which PPy particles are aggregated. In adsorption studies of PD in an aqueous medium, the pH, the contact time between the material and analyte and equilibrium concentration were evaluated. The first study carried out was the influence of pH on the adsorbed amount of PD, the optimum pH chosen for the experiments being 2.0 and 6.0 for CF and PPy/CF, respectively. In the kinetic study, adsorption occurred rapidly and equilibrium times were achieved within 30min (CF) and 15min (PPy/CF). The kinetic data were analysed using four models: pseudo-first-order, pseudo-second-order, Elovich and intraparticle diffusion and the adsorption kinetics were best described by the pseudo-second-order model with R2=0.999 for both materials, indicating that a chemical adsorption occurred. The Langmuir, Freundlich, Sips, single-site Langmuir–Freundlich and dual-site Langmuir–Freundlich models were used to analyse the adsorption equilibrium data obtained by the variation of the PD concentration in the aqueous solution and the dual-site Langmuir–Freundlich model presented the best fits, CF: R2=0.982 and PPy/CF: R2=0.997, indicating that there are two types of sites available for adsorption, homogeneous and heterogeneous, in the assessed materials. In addition, the composite had the best maximum adsorptive capacity, Q=210.07mgg−1, while the CF presented Q=50.33mgg−1.
Herein, we presented the preparation of cellulose fibre (CF) decorated with polypyrrole (PPy) as an efficient adsorbent for removal of potassium diclofenac (PD) from aqueous medium, which can be used in separation process as solid phase extraction and chromatographic and electrophoretic techniques. The kinetics and isotherms studies showed a great potential of this material for this purpose. The PPy/CF were prepared via in situ polymerization and characterized by FTIR, TG and SEM.
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•New composite adsorbent (PPy/CF) was easily synthesized and well characterized.•PPy/CF was efficient for removal of PD from aqueous medium.•Adsorption studies allowed understanding the adsorption mechanism of PD onto PPy/CF.•PPy/CF showed excellent adsorption capacity compared to pure CF.•PPy/CF presented good stability over a wide pH range (pH2–10).
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The purpose of this study was to evaluate the effect of the adsorption of the potassium diclofenac (PD) on a pristine multiwalled carbon nanotube (pristine MWCNT) and on the composite ...formed by the addition of polypyrrole (PPy) to pristine MWCNT, named PPy/MWCNT. They were characterized by scanning electron microscopy, infrared spectroscopy, thermogravimetric analysis, Brunauer–Emmett–Teller, surface wettability and point of zero charge. The adsorption procedure of the PD in the adsorbent materials was analysed by varying some parameters. After optimization, the materials exhibited adsorption of 93.48% and 94.98%, for pristine MWCNT and PPy/MWCNT, respectively. The kinetic data were adequately adjusted to the pseudo-second-order model for the two materials. The results of the isotherm studies showed that the models that best fit the data were the dual-site Langmuir–Freundlich and Fritz-Schlunder models, presenting Q = 59.67 mg g–1 for the pristine MWCNT and Q = 229.93 mg g–1 for the PPy/MWCNT. The thermodynamic study showed that from the values of ΔH and ΔG it was possible to conclude that an endothermic and favourable adsorption process occurred during the study. It can be observed that the addition of PPy in MWCNT causes a significant improvement in the maximum adsorption capacity of pristine MWCNT.
As an alternative to traditional adsorbents, mesoporous magnetic polypyrrole (MMPPy) was first used as an adsorbent for the removal of acid, neutral, and basic pharmaceutical compounds considered ...aqueous pollutants. Ibuprofen (IBU, acid), caffeine (CAF, neutral), and bupropion (BUP, basic) were chosen as adsorbates and applied in adsorption studies. They proved to be pH dependent of the aqueous solution and the best results were found at pH 4 for IBU and CAF and pH 7 for BUP and 60 mg was the optimal amount of adsorbent to be used in the studies. Adsorption was extremely fast and the equilibrium was reached up to 180 s. The adsorption data of all analytes could be well interpreted by the pseudo second-order kinetic model and the dual-site Langmuir-Freundlich isotherm model. The adsorption capacities obtained by the dual-site Langmuir-Freundlich model were 53.67 mg g
−1
, 16.74 mg g
−1
, and 24.72 mg g
−1
for IBU, CAF, and BUP, respectively. Thermodynamic parameters revealed that IBU adsorption becomes spontaneous as temperature increases and CAF and BUP adsorption occurs through a non-spontaneous process. In addition, this study shows endothermic nature of the adsorption process. Analytes were desorbed using an aqueous solution at pH 10 for IBU, pH 7 for CAF, and pH 4 for BUP and then the material was regenerated successfully. The results suggest that MMPPy can be efficiently used in the removal of different organic analytes found in contaminated water.
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•Synthesis of the new MIP based on poly(1-VI-co-TMPTMA).•Excellent adsorbent material for analytical selective extraction of AVM and MBM.•Efficient PT-MIP-SPE coupled HPLC-UV method ...was developed.•PT-MIP-SPE is a simple, inexpensive, versatile, and easy to perform technique.•PT-MIP-SPE was used in extraction of AVM and MBM of mineral water and grape juice.
A simple HPLC method was developed for the determination of abamectin (ABA), eprinomectin (EPR), and moxidectin (MOX). Pipette-tip molecularly imprinted polymer solid-phase extraction (PT–MIP–SPE) using poly(1-vinylimidazole-co-trimethylolpropane trimethacrylate) as a selective adsorbent material was studied in detail, including the washing solvent, type and volume of eluent, pH, quantity of adsorbent material and sample volume. The performance criteria for linearity, sensitivity, precision, accuracy, recovery, robustness and stability have been assessed and were within the recommended guidelines. The mean extraction recoveries/relative standard deviation for ABA 1b, EPR, ABA 1a and MOX were 98.77 ± 3.82%, 88.19 ± 2.57%, 110.54 ± 1.52% and 100.42 ± 0.59%, respectively. Finally, the results proved that PT–MIP–SPE coupled to HPLC–UV is an economical, simple and easy-to-perform technique, and presented a high potential for extraction of macrocyclic lactones in mineral water and grape and juice samples.
In this work, we developed a HPLC method for the multidetermination of avermectins (AVM) (abamectin—ABA 1b and ABA 1a, eprinomectin—EPR, and ivermectin—IVM) and milbemycins (moxidectin—MOX) in milk ...samples using polypyrrole (PPy) as adsorbent material in pipette-tip solid-phase extraction (PT–PPy–SPE). PPy was characterized by scanning electron microscopy, thermogravimetric analysis, Fourier transform infrared spectroscopy, and X-ray diffraction and the data agreed with the literature. The sample preparation included the clean-up of the milk by protein precipitation (PP) with acetonitrile and extraction of the analytes by PT–PPy–SPE. The chromatographic method was developed in reverse phase and isocratic mode with flow rate at 1.2 mL min
−1
and ultraviolet detection at 250 nm. The mobile phase composition was acetonitrile:methanol:water (55:25:20,
v
/
v
/
v
). The studied parameters and the optimized conditions for the sample preparation were washing solvent (300 μL water), volume and type of eluent (500 μL methanol), volume and pH of sample (1 mL and pH 10), amount of adsorbent material (50 mg PPy), and without addition of salt (NaCl). The method was linear over the concentration range from 20 to 3000 ng mL
−1
with coefficients of correlation (
r
) ≥ 0.99 for all analytes and recoveries around 100%. The method developed and validated was used for the analyses of real milk samples from cow treated with Ivomec
®
(IVM 3.5%), in which were found 21.51 ± 2.94 ng mL
−1
of IVM. Finally, the results proved that PT–PPy–SPE coupled to HPLC–UV was economical, simple, and easy-to-perform technique.
Graphical abstract
Pipette-tip solid phase extraction using polypirrole as adsorbent material for determination of avermectins and milbemycins in milk
Conductive polymers have been used as adsorbents to remove organic pollutants from aqueous samples. In this study, pristine polypyrrole (PPy) was used for the first time in the removal of potassium ...diclofenac (PD) and moxidectin (MOX) from aqueous solutions.PPy was properly characterised by scanning electron microscopy, thermogravimetric analysis, infrared spectroscopy, textural properties, wettability, and point zero charge. Through the characterisation results, it was observed that the adsorbent showed be favourable to adsorption, high temperature of thermal degradation, bands characteristic of the PPy,mesopore structures, and hydrophilicity. The results pointed that pH 6 favoured the removal, reaching percentages of 95.26% for PD and 99.75% for MOX.The kinetic data followed the model of pseudo second-order (PD: R
2
= 0.872 and MOX: R
2
= 0.887) with equilibrium reached in 20 min for PD and MOX. OThe best fit isotherm model was the dual-site Langmuir-Freundlich (R
2
> 0.99), with maximum capacity adsorption of 221.23 mg g
−1
for PD and 87.46 mg g
−1
for MOX. Finally, the thermodynamic study showed that the adsorption process was spontaneous and endothermic. Through the reuse study, it was possible to show a good cost-benefit ratio when using the developed adsorbent material, since it can be used several times without losing its adsorption capacity. Finally, PPy showed great potential to be used in the adsorption of compounds with different physicochemical properties.
Abstract This work aims to develop analytical methods using high-performance liquid chromatography with a diode array detector (HPLC-DAD) for analysis and quantification of avermectins (AVMs) and ...milbemycins (MBMs) in bulk samples. First, the methods were optimized and some parameters such as temperature, flow rate, injection volume and mobile phase with different proportions of solvents were evaluated. The best chromatographic conditions were obtained using the Phenomenex® C18 (150 × 4.60 mm, 5 μm) column at a temperature of 20 °C, flow rate of 1.2 mL min-1, injection volume of 20 μL, and detection at 250 nm. Acetonitrile: ultrapure water (87: 13, v/v) was used as mobile phase for moxidectin and eprinomectin, and acetonitrile: methanol: ultrapure water (53: 35: 12, v/v/v) for abamectin and ivermectin. Under these conditions satisfactory results were obtained, with appropriate limits of detection and quantification, acceptable linearity, precision, accuracy, and robustness. These methods satisfy the need for analytical methods for the multi-determination of MBMs and the B1a and B1b forms of AVMs by HPLC-DAD, which can be considered simple, effective, innovative and should aid in the development of the field.
Herein, poly(aniline‐co‐pyrrole) has been synthetized and investigated to adsorb phenylbutazone (PBZ), ceftiofur (CEF) and prednisolone (PRD) in aqueous medium as proof of concept. After proper ...adsorbent characterization, some studies were carried out in batch process, i. e., contact time, pH, and concentration. The adsorption mechanism has been conducted using kinetic and isothermal models. It was found that the reaction equilibrium was reached in 20 min for all analytes. The best fit for the experimental data were obtained employing the models of dual‐site Langmuir–Freundlich, Fritz–Schlunder and Langmuir, with R2=0.999, 0.952 and 0.974, for PBZ, CEF and PRD, respectively. For PBZ, CEF and PRD, poly(aniline‐co‐pyrrole) provided a Qmax=238.8 mg g−1 and Kmax=0.086 L g−1, Q=0.028 mg g−1 and Kmax=3.258 L g−1, Q=13.66 mg g−1 and KL=0.005 L g−1, respectively. Finally, the copolymer was evaluated in solid phase extraction, which showed recovery around 70 % for PBZ, offering also exciting opportunities for further application in the separation process.
An adsorbent for solid phase extraction of analytical methods and the removal of pollutants from wastewater was synthesized by co‐polymerization between aniline and pyrrole. Significant characteristics of the copolymer, such as its strong adsorptive capacity, resistance to pH changes, heterogeneous surface, improved thermal stability, and reusability, made it suitable for use as stationary phases in separation processes.
The composite polyaniline/multiwalled carbon nanotube (PAni/MWCNT, 1:0.1 w/w) was developed with the intention of binding the adsorbent properties of two materials and using it to adsorb ...pharmaceuticals from aqueous media. PAni/MWCNT was characterized by scanning electron microscopy, thermogravimetry, infrared spectroscopy, pH at the point of zero charge, and the effect on the surface wettability of the material. As proof of concept, adsorption studies were carried out using meloxicam (MLX) as the pharmaceutical and it was evaluated as a function of pH, temperature, ionic strength, contact time and variation in concentration. Kinetics and isothermal models were applied to evaluate the mechanism of the adsorption process. The best MLX adsorption result was at pH 2 with 6 min of contact with PAni/MWCNT. The kinetics models that fitted the experimental data were pseudo-second order and Elovich and the kinetics model was the dual-site Langmuir–Freundlich. Both models suggest that the adsorption occurs by the chemical nature of the surface and in the pores of the energetically heterogeneous composite. The PAni/MWCNT presented an adsorption capacity of 221.2 mg g−1, a very good value when compared with the literature and can be used to remove pharmaceuticals from aqueous environments.
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•New composite based on PAni/MWCNT was synthesized by simple methodology.•Efficient adsorbent for environmental and analytical processes.•PAni/MWCNT can be applicable for removal of pharmaceutical from aqueous media.•PAni/MWCNT showed potential for use in sample preparation.
