Magnetic cellulose ionomer/layered double hydroxide: An efficient anion exchange platform with enhanced diclofenac adsorption property

Cellulose-based adsorbents for solid phase extraction and recovery of pharmaceutical residues from water

Cellulose has attracted interest from researchers both in academic and industrial sectors due to its unique structural and physicochemical properties. The ease of surface modification of cellulose by the integration of nanomaterials, magnetic components, metal organic frameworks and polymers has made them a promising adsorbent for solid phase extraction of emerging contaminants, including pharmaceutical residues. This review summarizes, compares, and contrasts different types of cellulose-based adsorbents along with their applications in adsorption, extraction and pre-concentration of pharmaceutical residues in water for subsequent analysis. In addition, a comparison in efficiency of cellulose-based adsorbents and other types of adsorbents that have been used for the extraction of pharmaceuticals in water is presented. From our observation, cellulose-based materials have principally been investigated for the adsorption of pharmaceuticals in water. However, this review aims to shift the focus of researchers to the application of these adsorbents in the effective pre-concentration of pharmaceutical pollutants from water at trace concentrations, for quantification. At the end of the review, the challenges and future perspectives regarding cellulose-based adsorbents are discussed, thus providing an in-depth overview of the current state of the art in cellulose hybrid adsorbents for extraction of pharmaceuticals from water. This is expected to inspire the development of solid phase exraction materials that are efficient, relatively cheap, and prepared in a sustainable way.

Nonsteroidal anti-inflammatory drug monitoring in serum: a Tb-MOF-based luminescent mixed matrix membrane detector with high sensitivity and reliability

The identification of drugs or biomolecules for public health monitoring requires facile analytical technologies with excellent sensitivity, portability and reliability. In the past decades, different sensing materials have inspired the development of various bioanalytical strategies. However, sensing platforms based on powder materials are not suitable for medical diagnosis, which limits further exploration and application of biosensors. Herein, a point-of-care testing (POCT) membrane was designed from an energy competition mechanism and achieved the detection of the nonsteroidal antiphlogistic diclofenac, and exhibited remarkable testing efficacy at the ppb level. The mixed matrix membrane (MMM) sensor consists of electrospun polyacrylonitrile nanofibers and luminescent Tb-MOFs and possess the advantages of high stability, outstanding anti-interference ability, efficient detection (LOD = 98.5 ppb) and easy visual recognition. Furthermore, this MMM sensor exhibits excellent recyclability in serum, which is beneficial for developing a portable and convenient device to distinguish diclofenac in practical sensing applications. Meanwhile, the feasibility and mechanism of this recyclable sensor were verified by theory and experiments, indicating that it is a promising device for diclofenac detection in biological environments to evaluate the toxic effect caused by the accumulation of nonsteroidal drugs.

Removal of naproxen and diclofenac using magnetic nanoparticles/nanocomposites

Magnetic iron oxide and iron/copper nanoparticles were synthesized using Lathyrus brachypterus extract, and then magnetic Fe₃O₄–CS, Fe₃O₄–AT, Fe/Cu–CS and Fe/Cu–AT nanocomposite beads were synthesized using chitosan and alginate natural polymers. They were used for both adsorption and heterogeneous catalysts for the catalytic wet peroxidation (CWPO) of naproxen (NPX), diclofenac (DCF) and NPX + DCF drugs which are important micro-organic pollutants, separately and together (NPX + DCF) from aqueous media. In adsorption studies, the drugs were adsorbed very quickly in the first minutes and then, desorbed in between 8 and 10 min. In competitive adsorption, the adsorbents showed selective properties for DCF and NPX. In CWPO technique, drug removal was achieved in 9 min with a conversion capacity of 92% for DCF with Fe/Cu–CS and 84% for NPX with Fe/Cu–AT optimum experimental conditions, such as pH 5, 30% of H₂O₂, 100 mg catalyst and 298 K. Based on reusability of the catalysts, it was seen that there was a slight decrease in the removal efficiencies in the third cycle and the stable and active structure of the catalyst was preserved to the desired extent. Furthermore, the oxidation reaction was in good agreement with the pseudo-first-order kinetic model.

Preparation of amino-modified cellulose aerogels and adsorption on typical diclofenac sodium contaminant

A new functional cellulose aerogel (Cell@PEI) with high adsorption efficiency was prepared for the removal of diclofenac sodium (DCF) by ammonification cross-linked polyethyleneimine (PEI) with the surface of cellulose. The fabricated Cell@PEI adsorbent was characterized using field emission scanning electron microscopy (FESEM), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS), etc. The results demonstrated that the Cell@PEI exhibited a distinct three-dimensional cell structure and was rich in functional groups, i.e., -OH, C = O, -NH₂, and C = C. The Cell@PEI presented a stable crystal structure and large specific surface area (241.41 m²·g^-1), which was approximately 42 times as much as bare cellulose aerogel (5.82 m²·g^-1). In addition, a series of adsorption experiments showed that the adsorbent had good adsorption performance for DCF with a maximum adsorption capacity of 294.12 mg·g^-1. Furthermore, the adsorption of DCF on Cell@PEI was well corresponded with the Langmuir isotherm and pseudo-second-order adsorption model. Thermodynamic study proved that adsorption was a spontaneous exothermic reaction. Moreover, the introduction of PEI into Cell@PEI aerogel enhanced the electrostatic interaction and hydrogen bonding, promoting DCF adsorption. Importantly, the Cell@PEI aerogel could be reused up to five times desorbed by NaOH (0.5 mol/L). Considering the above results, the fabricated aerogel material can be applied to remove organic pollutants.

Preferable phosphate sequestration using polymer-supported Mg/Al layered double hydroxide nanosheets

The efficient removal of phosphate from waters is critical to mitigating eutrophication. Recently, layered double hydroxides (LDHs) have been believed to be promising adsorbents for phosphate removal. Nevertheless, the scaled-up application of LDHs is limited by the difficulties of separation, excessive pressure drops, and potential metal leaching. In this study, a millimeter-sized nanocomposite, MgAl-201, was fabricated by impregnating Mg/Al LDH nanosheets into a polystyrene anion exchanger D201. The resulting MgAl-201 combines the inherent affinity of Mg/Al LDH toward phosphate and the excellent hydrodynamic performance of the support material. Benefiting from the shielding effect from the cross-linked polymeric host, MgAl-201 exhibits satisfactory chemical stability in the range of pH 3-11 with a negligible metal release. Adsorption experiments show that MgAl-201 has superb applicability to neutral phosphate-contaminated waters. It reaches adsorption equilibrium within 270 min, and the maximum adsorption capacity calculated by the double Langmuir model is 52.0 mg/g. Meanwhile, MgAl-201 exhibits more preferable adsorption toward phosphate than D201 when coexisting anions are at relatively high levels. FTIR and XPS surveys revealed that two distinct adsorption interactions were involved in phosphate removal, that is, electrostatic interactions from the quaternary ammonium groups bonded on the host and the interlayer exchangeable anions in the encapsulated Mg/Al LDH, and specific inner-sphere complexation from the -OH groups in the Mg/Al LDH layers. For wastewater application, a satisfactory treatable volume of 580 BV was achieved to reduce the effluents from 2.0 mg/L to 0.5 mg/L, which was up to 8 times that of the traditional anion exchanger D201. Furthermore, MgAl-201 could be easily regenerated using the Na₂CO₃-NaCl binary solution and maintained good reusability without significant capacity loss after 5 adsorption-desorption cycles. The results suggest that MgAl-201 is of great application capability for preferable phosphate sequestration in advanced wastewater treatment.

Understanding the factors affecting adsorption of pharmaceuticals on different adsorbents - A critical literature update

Remediation of emerging pharmaceutically active compounds (PhACs) as micropollutants in wastewater is of foremost importance as they can cause extremely detrimental effects on life upon bioaccumulation and generation of drug-resistance microorganisms. Presently used physicochemical treatments, such as electrochemical oxidation, nanofiltration and reverse osmosis, are not feasible owing to high operating costs, incomplete removal of contaminants along with toxic by-products formation. Adsorption with the utilization of facile and efficient nanoparticulate adsorbents having distinctive properties of high surface area, excellent adsorption capacity, ability to undergo surface engineering and good regeneration displays great potential in this aspect along with the incorporation of nanotechnology for effective treatment. The application of such nanosorbents provides optimal performance under a wide range of physicochemical conditions, decreased secondary pollution with reduced mechanical stress along with excellent organic compound sequestration capacity, which in turn improves the quality of potable water in a sustainable way compared to current treatments. The present review intends to consolidate the range of factors that affect the process of adsorption of different PhACs on to various nanosorbents and also highlights the adsorption mechanism aiding in the retrieval.

High adsorption of sodium diclofenac on post-synthetic modified zirconium-based metal-organic frameworks: Experimental and theoretical studies

Water pollution by pharmaceuticals is currently a great concern due to their ecological risks. In this study, zirconium-based metal-organic frameworks (UiO-66-(COOH)₂) were used for removal of the nonsteroidal anti-inflammatory drug (NSAID) diclofenac sodium (DCF). They have been synthesized using a hydrothermal method. Copper and iron metal ions were incorporated in the framework using post-synthetic modification techniques to produce UiO-66-(COOCu)₂ and UiO-66-(COOFe)₂. The resulted MOFs were characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FT-IR), scanning/transmission electron microscopy, and Brunauer-Emmett-Teller. The effects of the pH, initial concentration, and adsorption time on the adsorption process of diclofenac were studied. The maximum adsorption capacities obtained on UiO-66-(COOH)₂, UiO-66-(COOCu)₂, and UiO-66-(COOFe)₂ were 480.5, 624.3, and 769.1 mg/g, respectively. The adsorption of diclofenac was found to be better fitted with Langmuir isotherm and pseudo-second-order kinetic models. The adsorption mechanism was investigated using XRD, FT-IR, density functional theory and Monte Carlo simulation, in which the latter method was used to calculate the adsorption energies and determine the possible interactions between diclofenac and the adsorbents. UiO-66-(COOH)₂, UiO-66-(COOCu)₂, and UiO-66-(COOFe)₂ exhibited good recyclability for diclofenac removal, which confirms the sustainability of these materials.

Facile Synthesis of g-C3N4/MoO3 Nanohybrid for Efficient Removal of Aqueous Diclofenac Sodium

Graphitic carbon nitride modified by molybdenum trioxide (g-C₃N_4/MoO₃) as a nanohybrid was synthesized by co-precipitation method. Here, g-C₃N₄/MoO₃ nanohybrid was used for the first time as an adsorbent for the pharmaceutical drug, diclofenac, (an aqueous micropollutant) from water to mitigate its possible environmental toxic effects. Compared to pristine components, the nanohybrid exhibited better adsorptive removal of diclofenac. Adsorption was enhanced with increment in MoO₃ content from 1 to 3 wt %; however further increment in MoO₃ content resulted in lower adsorption capacity due to agglomeration of MoO₃ particles over g-C₃N₄. 162 mg g⁻¹ adsorption capacity was achieved for 300 mg L⁻¹ diclofenac in solution with 1 g L⁻¹ adsorbent at pH = 6. Adsorption of diclofenac over g-C₃N₄ /MoO₃ followed pseudo 2nd order kinetics. Temkin, Langmuir, Dubinin Radushkevich and Freundlich isotherm models were applied on the experimental results concluding that diclofenac adsorption over g-C₃N₄/MoO₃ followed the Langmuir isotherm. The adsorption mechanism could be explained by the π–π interaction between aromatic rings of diclofenac and g-C₃N₄/MoO₃ (3%) nanohybrid, which is also evident by the FTIR results. This study presents the facile fabrication of a 2nd generation adsorbent for the treatment of diclofenac contaminated water that may as well help achieve the removal of other micropollutants form water.

A facile synthesis of bismuth oxychloride-graphene oxide composite for visible light photocatalysis of aqueous diclofenac sodium

In this study, bismuth oxychloride/graphene oxide (BiOCl-GO) composite was fabricated by facile one pot hydrothermal method. The pure BiOCl and BiOCl-GO composite was characterized by X-ray diffraction, Transmission electron microscopy X-ray photoelectron spectroscopy and UV-Vis diffuse reflectance spectroscopy. The synthesized composite was then assessed for photocatalytic degradation of diclofenac sodium (DCF) in visible as well as direct solar light and UV irradiation. Results indicated that the photocatalytic removal efficiency of DCF was significantly affected by dose of catalysts, pH value and source of light. The results reveled that degradation efficiency of BiOCl-GO for DCF reduced from 100 to 34.4% with the increases in DCF initial concentration from 5 mg L^-1 to 25 mg L^-1. The solar light degradation of DCF using BiOCl-GO was achieved with apparent rate constant 0.0037 min^-1. The effect of scavengers study revealed that superoxide ions and holes were mainly responsible for DCF degradation. The regeneration study indicates that BiOCl-GO composite can be successfully recycled up to the five cycles. The study revealed the effectiveness of one pot hydrothermal method for the fabrication of BiOCl-GO composite.

Amine functionalized egg albumin hydrogel with enhanced adsorption potential for diclofenac sodium in water

The removal of diclofenac sodium (DFS) from wastewater has attracted increasing attention because it is within the extensively prescribed nonsteroidal anti-inflammatory drugs and pose ecotoxicity. Therefore, fabrication of versatile adsorbents of low-cost, higher-effectiveness and excellent recyclability is significant for the treatment of DFS contaminated wastewater. This work reports a promising biobased egg albumin (ALB) hydrogel functionalized with a large density of adsorptive amine sites via polyethyleneimine (PEI). The composite ALB/PEI hydrogel demonstrated an excellent DFS removal capacity, i.e. 232.5 mg/g, in an optimum experimental condition (pH∼6; contact time∼180 min; adsorbent dosage∼0.5 g/L) which revealed to be considerably higher or competitive than many reported adsorbents. The adsorption isotherms better accorded with the Langmuir model and the kinetics with the pseudo second-order model, indicating the mono-layer chemisorption process. Besides, the regeneration steps up to four sequential adsorption/desorption cycles demonstrated an excellent reusability. The Fourier-transform infrared spectrometry (FTIR), and X-ray photoelectron spectroscopy (XPS) results implied that the adsorption process followed via the electrostatic interactions, hydrogen bonding, and π-π stacking between the functionality of hydrogel and aromatic rings of DFS. Considering the low-cost, and an excellent DFS removal capacity, the natural composite ALB/PEI hydrogel could be a promising adsorbent for the treatment of DFS contaminated wastewater.

Modified biochar from Moringa seed powder for the removal of diclofenac from aqueous solution

In this study, Moringa seed powder (M_SP) was pyrolyzed at 450 °C to synthesize Moringa seed powder biochar (M_SPB) and treated with phosphoric acid (H₃PO₄) to synthesize phosphate-modified Moringa seed powder biochar (M_SPB-HPO) as an adsorbent for the removal of diclofenac (Dfc) from aqueous solution. Fourier transform infrared (FTIR) analysis, energy dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), and pH point of zero charge (pH_pzc) were conducted to give more insight into the adsorbent's properties. The SEM analysis showed the transformations in the surface morphology from the parent material to the synthesized materials after the thermal and acid treatment. EDS analysis revealed the variation in the elemental composition of the materials prior to and after adsorption of Dfc ions. The FTIR analysis showed changes and peak intensities of functional groups involved in Dfc removal. The pH_pzc showed the charge carried by M_SPB-HPO in different pH conditions. Isotherm data best matched the Sips model, and the pseudo-second-order model best described the adsorption kinetics. The maximum adsorption capacity of M_SPB-HPO by Sips model was found to be 100.876 mg g^-1.

Iron-rich microorganism-enabled synthesis of magnetic biocarbon for efficient adsorption of diclofenac from aqueous solution

Microorganisms in nature have been suggested as effective synthetic platform for functional materials construction. In this study, we cultured a typical white rot fungus of Phanerochaete chrysosporium in iron-containing medium to obtain iron-rich biomass, serving as sole precursor for magnetic biocarbon synthesis. The accumulated iron in biomass reached to 4.6 wt%. After carbonization and activation, microporous magnetic biocarbon (Fe/BC) with high specific surface area of 1986 m² g^-1 was obtained. When applied as adsorbent for a model pharmaceutical (diclofenac sodium, DCF) removal from aqueous solution, a high adsorption capacity of 361.25 mg g^-1 was found for the developed Fe/BC. Systematic isotherm, kinetic, thermodynamic and recycle studies were conducted to investigate adsorption behaviors of DCF onto Fe/BC. This work not only provides a novel strategy for magnetic biocarbon construction, but also envisions new perspective on the utilization of a variety of microorganisms in nature for functional materials preparation.

Adsorptive decontamination of diclofenac by three-dimensional graphene-based adsorbent: Response surface methodology, adsorption equilibrium, kinetic and thermodynamic studies

Pharmaceutical residues are emerging pollutants in the aquatic environment and their removal by conventional wastewater treatment methods has proven to be ineffective. This research aimed to develop a three-dimensional reduced graphene oxide aerogel (rGOA) for the removal of diclofenac in aqueous solution. The preparation of rGOA involved facile self-assembly of graphene oxide under a reductive environment of L-ascorbic acid. Characterisation of rGOA was performed by Fourier transform infrared, scanning electron microscope, transmission electron microscopy, nitrogen adsorption-desorption, Raman spectroscopy and X-ray diffraction. The developed rGOA had a measured density of 20.39 ± 5.28 mg/cm³, specific surface area of 132.19 m²/g, cumulative pore volume of 0.5388 cm³/g and point of zero charge of 6.3. A study on the simultaneous interactions of independent factors by response surface methodology suggested dosage and initial concentration as the dominant parameters influencing the adsorption of diclofenac. The highest diclofenac adsorption capacity (596.71 mg/g) was achieved at the optimum conditions of 0.25 g/L dosage, 325 mg/L initial concentration, 200 rpm shaking speed and 30 °C temperature. The adsorption equilibrium data were best fitted to the Freundlich model with correlation coefficient (R²) varying from 0.9500 to 0.9802. The adsorption kinetic data were best correlated to the pseudo-first-order model with R² ranging from 0.8467 to 0.9621. Thermodynamic analysis showed that the process was spontaneous (∆G = - 7.19 to - 0.48 kJ/mol) and exothermic (∆H = - 12.82 to - 2.17 kJ/mol). This research concluded that rGOA is a very promising adsorbent for the remediation of water polluted by diclofenac.

Fast sono assisted ferrofluid mediated silver super - Adsorption over magnesium ferrite-copper sulfide chalcogenide with the aid of multivariate optimization

This research focuses on the development of a fast ultrasonic assisted ferrofluid mediated methodology to obtain the optimum conditions for silver adsorption from aqueous solutions. For this purpose magnesium ferrite-copper sulfide chalcogenide was synthesized and employed as an efficient nanosorbent. The sorbent was characterized with energy-dispersive X-ray spectroscopy (EDX), field emission scanning electron microscopy (FE-SEM), X-ray powder diffraction (XRD) and vibrational sample magnetometry (VSM) techniques. For obtaining the optimal operating conditions of silver adsorption, response surface methodology (RSM) was used. Tests were performed by Box-Behnken design (BBD). The value of optimum conditions for silver adsorption include pH=2.5, adsorbent dosage=10.0mg, sonicating time=1min and ionic strength=2.2%. According optimum conditions, percentage of removal should be 99.34%. With replication of similar experiment (n=6) average percentage of 100±0.95% was obtained for Ag⁺ adsorption which shows good agreement between predicted and experimental results. Silver ion adsorption follow Langmuir model with maximum sorption capacity of 2113mgg^-1. Ultrasonic power helped to prepare ferrofluid and demonstrated that had an important role in better dispersing of it in solution and efficient adsorption of analyte.