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Pharmaceuticals are used to improve the lives of people across the globe. The high demand for their fabrication and use causes a very serious environmental threat since their presence is ubiquitous in aqueous matrices. For this reason, the synthesis, characterisation, and efficiency of three chitosan-based materials to eliminate pharmaceutical mixtures from aqueous solutions were examined in the present study. The target mixture comprised seven widely used drugs: carbamazepine, cyclophosphamide, adefovir, levofloxacin, metronidazole, glibenclamide, and trimethoprim. The grafting of poly(ethylene imine) and poly(acrylamide) on the chitosan structure allowed its physical characteristics to be controlled. An adsorption assessment was performed at different pH values, and it was concluded that pH = 4 was the optimum value. The adsorption kinetics revealed that the adsorption of a drug mixture involves a combination of physical and chemical adsorption. The adsorption process appeared to be finished after 1 h for all compounds of the studied mixture, with CS-AMI exhibiting the fastest kinetics. Mass adsorption experiments were also carried out to determine its effects. Overall, the grafting process significantly increased the adsorption capacity over the pristine material. Specifically, the highest capacity increase for CS-PEI was ~220% for carbamazepine, and for CS-AMI, it was 158% for trimethoprim. FT-IR, SEM, and XRD were used for the characterisation of the polymers. Based on the findings, the three materials are suggested as very effective adsorbents for the elimination of medicine residues from aqueous matrices. [ABSTRACT FROM AUTHOR]

In this experimental study, the use of 5-hydroxymethyl-furfural (HMF) organic compound as a grafting agent to chitosan natural polymer (CS) was examined. One optimized chitosan derivative was synthesized, and then tested (CS-HMF), in order to uptake nickel, mercury, and barium metal ions from single- and triple-component (multi-component) aqueous solutions. The characterization of the material before and after the metal uptake was achieved by scanning electron microscopy (SEM). The ability of the adsorption of CS-HMF was tested at pH = 6. The adjusting of temperature from 25 to 65 °C caused the increase in the adsorption capacity. The equilibrium data were fitted to the models of Langmuir and Freundlich, while the data from kinetic experiments were fitted to pseudo-1st and pseudo-2nd order models. The best fitting was achieved for the Langmuir model (higher R2). The adsorption capacity for nickel, mercury, and barium removal at 25 °C (single component) was 147, 107, and 64 (mg/g), respectively. However, the total adsorption capacity for the multi-component was 204 mg/g. A thermodynamic study was also done, and the values of ΔG0, ΔH0, and ΔS0 were evaluated. [ABSTRACT FROM AUTHOR]

This work investigates the application of 5-hydroxymethyl-furfural (HMF) as a grafting agent to chitosan (CS). The material produced was further modified by cross-linking. Three different derivatives were tested with molecular ratios CS/HMF of 1:1 (CS-HMF1), 2:1 (CS-HMF2) and 10:1 mol/mol (CS-HMF3)) to remove Cu2+ and Cd2+ from aqueous solutions. CS-HMF derivatives were characterized both before, and after, metal ions adsorption by using scanning electron microscopy (SEM), as well as Fourier-transform infrared (FTIR) spectroscopy thermogravimetric analysis (TGA), and X-Ray diffraction analysis (XRD). The CS-HMF derivatives were tested at pH = 5 and showed higher adsorption capacity with the increase of temperature. Also, the equilibrium data were fitted to Langmuir (best fitting) and Freundlich model, while the kinetic data to pseudo-first (best fitting) and pseudo-second order equations. The Langmuir model fitted better (higher R2) the equilibrium data than the Freundlich equation. By increasing the HMF grafting from 130% (CS-HMF1) to 310% (CS-HMF3), an increase of 24% (26 m/g) was observed for Cu2+ adsorption and 19% (20 mg/g) for Cd2+. By increasing from T = 25 to 65 °C, an increase of the adsorption capacity (metal uptake) was observed. Ten reuse cycles were successfully carried out without significant loss of adsorption ability. The reuse potential was higher of Cd2+, but more stable desorption reuse ability during all cycles for Cu2+. [ABSTRACT FROM AUTHOR]

The main purpose of this study was to investigate the synthesis of some cross-linked carboxyl-grafted chitosan derivatives to be used as selective adsorbents for diclofenac (DCF) pharmaceutical compounds from aqueous mixtures. Four different materials were synthesized using succinic anhydride (CsSUC), maleic anhydride (CsMAL), itaconic acid (CsITA), and trans-aconitic acid (CsTACON) as grafting agents. After synthesis, scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), and X-ray diffraction (XRD) were performed before and after DCF adsorption. In addition, a complete adsorption evaluation was carried out for all materials studying some important parameters. The optimum pH was 4; the amino groups of DCF can be protonated at pH = 4 (–NH+), so this groups can easily attract the clear negatively carboxyl moieties (–COO−) of the chitosan adsorbents. The Qm for CsTACON was higher than those of the other materials, at all temperatures studied. By altering the temperature from 25 to 35 °C, an increase (16%) of Qm (from 84.56 to 98.34 mg g−1) was noted, while similar behavior was revealed after a further increase of temperature from 35 to 45 °C, improving by 5% (from 98.34 to 102.75 mg g−1). All isotherms were fitted to Langmuir, Freundlich, and Langmuir-Freundlich (L-F) models). In addition, a kinetic model was proposed taking into account not only the interactions but also the diffusivity of the molecule (DCF) into the polymeric network. The behavior of the prepared chitosan materials in simultaneously removing other compounds (synergetic or antagonistic) was also evaluated by experiments performed in mixtures. DCF presented the highest removal from the mixture in the order: CsTACON (92.8%) > CsITA (89.5%) > CsSUC (80.9%) > CsMAL (66.2%) compared to other pharmaceutical compounds (salicylic acid, ibuprofen and ketoprofen). Desorption was achieved by using different eluants (either water or organic). The highest desorption ability was found for acetone (100% for CsTACON, CsSUC, CsMAL and 77% for CsITA) for all materials. [ABSTRACT FROM AUTHOR]

In this study the adsorption of a mixture of seven pharmaceutical compounds on virgin and aged polylactic acid (PLA) microplastics (MPs) was investigated. PLA MPs were aged under UV radiation and simulated solar light (SSL) creating three types of MPs: i) virgin, ii) UV-aged and iii) SSL-aged PLA-MPs. The different PLA-MPs were characterized with various characterization techniques (FTIR, SEM, TGA) which revealed modifications on the surface of the aged MPs like cracks and pits, creating more adsorption sites. Pseudo-first, pseudo-second and the intraparticle diffusion model were applied to explore the mechanism and the rate limiting step of the adsorption mechanism. Isothermal study was also conducted and revealed better fitting with the Freundlich model indicating a multi-layer coverage on the MPs surface. Aging appears to enhance the adsorption capacity of the target compounds on the PLA-MPs for both types of aged MPs however the UV-aged showed higher uptake. Finally, the effect of other parameters, like the pH or the type of the water matrix were also investigated offering a deeper insight on the adsorption mechanism of the target compounds. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Removal of NSAIDs, anti-epileptic and antihypertensive pharmaceutical mixture from aqueous matrices by using of adsorption. • Synthesis and characterisation of six different chitosan/polyvinyl alcohol/graphene oxide and reduced graphene oxide materials. • The highest adsorption capacity was observed for GO and rGO (0.2%) • The highest adsorption removal was found for valsartan and diclofenac. • Desorption was accomplished by using different aqueous eluents (of pH 2–10) and organic solvents. The main scope of this study is synthesis, characterization and implementation of new bio-based chitosan derivatives for the removal by adsorption of pharmaceutical mixtures from aqueous matrices. Six different materials of chitosan/polyvinyl alcohol were synthesized using an increasing quantity of graphene oxide and reduced graphene oxide (0.05%, 0.1% and 0.2%). A combination of different groups of pharmaceuticals was used as a model pollutant. Within this context, four non-steroidal anti-inflammatory drugs (diclofenac, ibuprofen, ketoprofen, paracetamol), one anti-epileptic (carbamazepine) and two antihypertensives (valsartan and irbesartan) were selected. The highest adsorption capacity was exhibited by the composites with the highest concentration of GO and rGO (0.2%), while the pollutants that presented the highest adsorption removal were valsartan and diclofenac. The adsorption process was appeared to be finished after 3 h for all compounds of the studied mixture (well-fitted to pseudo-2nd order model). The results indicated that the Langmuir model offered better match for the experimental data, while the adsorption capacity of adsorbents increased with the rise of the temperature. Overall, the highest adsorption capacities achieved at pH 10 (55 °C). Desorption was accomplished by using different aqueous eluents (with pH 2–10) and organic solvents. FTIR, SEM, EDS techniques were used to characterize the composition and morphology, and for the compounds detection the UHPLC system was used. [ABSTRACT FROM AUTHOR]

[Display omitted] • Disposal of five NSAIDs compounds mixture from aqueous matrices with adsorption process. • Preparation of three new orange peels-activated carbon materials by pyrolysis method. • Completed adsorbents characterisation and adsorption performance. • Equilibrium, kinetic and thermodynamic parameters were established. • Application of inexpensive biomass waste for environmental reason. In recent years, bio-based carbons derived from environmentally friendly biomass materials have received considerable attention because of their abundance, easy processability, tunable surface properties and relatively low cost. Herein, a simple, less hazardous and low-cost method for the synthesis of ultrahigh surface area activated carbon material was proposed using orange peels as a carbon source. Within this context, three different biosorbents were synthesized: activated carbon samples derived from orange peels after activation with (i) phosphoric acid by pyrolysis at 450 °C (ORPs-H 3 PO 4 (450)) and (ii) at 650 °C (ORPs-H 3 PO 4 (650)), as well as (iii) after activation with potassium hydroxide at 450 °C (ORPs-KOH(450)). Characterisation and morphology of all materials has been conducted using various characterization techniques as FTIR, BET and SEM. The adsorption capacity was evaluated in a multi-component fashion for a mixture of five NSAIDs, namely diclofenac (DCF), ibuprofen (IBF), ketoprofen (KPF), salicylic acid (SAL) and paracetamol (PAR). The evaluation of the adsorption was achieved by investigating several variables like the effect of the solution's pH, of contact time (kinetic modelling) and of the initial pharmaceuticals' concentration. Acidic pH (pH = 2) appeared to be the optimal pH value while the pseudo-second order kinetic model and the Langmuir model demonstrate better fitting to the adsorption kinetics and isotherms respectively. Increase of temperature from 25 to 35 °C appears to have a positive effect on the adsorption capacity and the negative values of ΔG0 indicated that all target pharmaceuticals were adsorbed spontaneously to the synthesized biosorbents. Aqueous eluents with different pH values were used to accomplish desorption while pH = 6 appears to the optimum pH value for the desorption of the target pollutants. [ABSTRACT FROM AUTHOR]

The aim of the present study is the evaluation of graphene oxide (GhO) as adsorbent material for the removal of beta-blockers (pharmaceutical compounds) in aqueous solutions. The composition and morphology of prepared materials were characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). Atenolol (ATL) and propranolol (PRO) were used as model drug molecules and their behavior were investigated in terms of GhO dosage, contact time, temperature and pH. Adsorption mechanisms were proposed and the pH-effect curves after adsorption were discussed. The kinetic behavior of GhO-drugs system was analyzed after fitting to pseudo-first and -second order equations. The adsorption equilibrium data were fitted to Langmuir, Freundlich and Langmuir–Freundlich model calculating the maximum adsorption capacity (67 and 116 mg/g for PRO and ATL (25 °C), respectively). The temperature effect on adsorption was tested carrying out the equilibrium adsorption experiments at three different temperatures (25, 45, 65 °C). Then, the thermodynamic parameters of enthalpy, free energy and entropy were calculated. Finally, the desorption of drugs from GhO was evaluated by using both aqueous eluants (pH 2–10) and organic solvents. [ABSTRACT FROM AUTHOR]

In the present study, two novel molecularly imprinted polymers (MIPs) with remarkable recognition properties for metformin and its transformation product, guanylurea, have been prepared for their selective, enrichment, isolation and removal from aqueous media. The prepared adsorbents were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and swelling experiments. The performance of the prepared MIPs was evaluated by various parameters including the influence of pH, contact time, temperature and initial compound concentration. The effects on the adsorption behavior of the removal process parameters were studied and the equilibrium data were fitted by the Langmuir and Freundlich models. Due to the imprinting effect, adsorption performance of MIPs was always superior to its corresponding NIP (non-imprinted polymer), with maximum adsorption capacity ∼80 mg g −1 for both MIPs. Stability and reusability of the MIPs up to the 5th cycle meant that they could be applied repeatedly without losing substantial removal ability. In the next step, the prepared MIP nanoparticles were evaluated as sorbents in a dispersive solid phase extraction (D-SPE) configuration for selective enrichment and determination of metformin and guanylurea in different aqueous matrices. Under the working extraction conditions, the D-SPE method showed good linearity in the range of 50–1000 ng L −1 , repeatability of the extractions (RSD 2.1–5.1%, n = 3), and low limits of detection (1.5–3.4 ng L −1 ). The expanded uncertainty of the data obtained was estimated following a bottom-up approach. The proposed method combined the advantages of MIPs and D-SPE, and it could become an alternative tool for analyzing the residues of METF and its transformation product GUA in complex water matrices, such as wastewaters. [ABSTRACT FROM AUTHOR]

In the present study, carrageenan microparticles were synthesized using spray-drying method and used as biosorbents for the removal of pharmaceutical compounds. The cross-linking reaction of iota -carrageenan (iCAR) and kappa -carrageenan (kCAR) with glutaraldehyde (GLA) at different concentrations (2.5% or 5% (w/w), mass of GLA per mass of CAR) was studied (iCAR/GLA2.5, iCAR/GLA5, kCAR/GLA2.5, kCAR/GLA5). The physicochemical properties of the novel cross-linked polymers were investigated by scanning electron microscopy (SEM), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FT-IR). Swelling studies were in accordance with the polymer properties, showing the lowest swelling degree (19%) by using the iCAR/GLA5 microparticles. The optimal kCAR/GLA5 microparticles were successfully employed for the removal of Metoprolol (MTPL) from aqueous samples. The adsorption capacity of the adsorbents was investigated using a batch adsorption procedure and the kinetics and thermodynamics of the adsorption process were further investigated. It was found that the adsorption isotherms agree well with the Langmuir–Freundlich model. The maximum adsorption capacity ( Q m ) was achieved in pH 6, whereas an increase of Q m was observed increasing the temperature (from 109 at 20 °C to 178 mg/g at 40 °C). Kinetic studies showed that the adsorption process on iCAR/GLA5 microparticles followed pseudo-second-order rate mechanism. Finally, a new phenomenological model of the adsorption process was proposed in order to extract information on the relevant sub-processes. [ABSTRACT FROM AUTHOR]

In this experimental study, the use of acrylic acid, and 1-vinylimidazole as monomers for the synthesis of one polymer (PVI) and one copolymer (PVI- co -PAA) was examined using trimethylolpropane trimethacrylate as the cross-linking agent. The synthesized polymeric materials were characterized using Fourier transform infrared spectroscopy (FTIR), BET analysis, Thermogravimetric analysis (TGA) and scanning electron microscopy (SEM) and were evaluated towards their adsorption efficiency for the removal of two non-steroidal anti-inflammatory drugs, ibuprofen (IBU) and diclofenac (DCF), from single-component aqueous solutions. Parameters like pH, contact time, initial concentration of the drug and temperature were examined for their possible effect to the process. Acidic conditions appear to favor the uptake of the studied compounds. Moreover, the adsorption equilibrium data were fitted to Langmuir and Freundlich models calculating the maximum adsorption capacity, while Langmuir model exhibited a better fit indicating monolayer coverage of the pharmaceuticals onto the surface of synthesized derivatives. Furthermore, increase of temperature from 25 to 65 ℃ caused an enhancement of the adsorption ability, for both polymeric materials. while thermodynamic analysis revealed the spontaneous and endothermic nature of the process. [Display omitted] • PVI and PVI- co -PAA polymers were synthesized. • Characterization was conducted with FTIR, TGA, BET and SEM analysis. • Acid pH appears to favor the process. • Equilibrium data exhibited better fitting to Langmuir model. • Thermodynamic analysis showed the spontaneous and endothermic nature of the process. [ABSTRACT FROM AUTHOR]

The goal of this work was the application of a synthesized cross-linked and grafted zwitterionic chitosan derivative to the removal of a mixture of five anti-inflammatory compounds from aqueous matrix. This floating polymer supported nanocomposite material consisting of bio-based chitosan (CS) and was synthesized by free radical polymerization, using acrylic monomer [2-(Methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (MEDSP) as grafting agent. The composition and morphology of new CS-MEDSP material was characterized before and after adsorption, by using different procedures, for instance Fourier Transform Infrared spectroscopy (FTIR), X-ray powder diffraction (XRD) and Scanning electron microscopy (SEM). As model pollutants a mixture of pharmaceuticals from the group of anti-inflammatories was employed: diclofenac, ibuprofen, ketoprofen, paracetamol and salicylic acid (equal concentrations). An adsorption assessment was performed at different pH values concluding that pH = 4 was the optimum value. By testing different isotherm equations, the equilibrium data for the adsorption of the target compounds were evaluated. For the detection of compounds, an LC-MS system was utilized, in both ionization modes. Accordingly, results indicated a high adsorption/desorption ability of tested material being suitable for disposal of the certain remedies from aqueous systems. [Display omitted] [ABSTRACT FROM AUTHOR]