Chris Bode-Aluko | Cape Peninsula University of Technology, Bellville (original) (raw)

Papers by Chris Bode-Aluko

Polymers

Textile single-use products are dominantly used for hygiene and personal care, many of which are ... more Textile single-use products are dominantly used for hygiene and personal care, many of which are non-biodegradable and are frequently discarded into sewerage systems, thus causing blockages. Thus, there is a need to move towards water-soluble textiles. This research study focuses on transforming or repurposing biomass material and synthetic reusable waste plastic materials to improve waste. Chitosan (CS) nanofibers could be used in single-use nonwoven fabric or biodegradable tissues, as the water-soluble properties of chitosan nanofibers make them the perfect material for single-use applications. Furthermore, CS was blended with polyethylene terephthalate (PET) polymer and PET-based waste plastic (CS-WPET) to slow the CS nanofibers’ water degradability and strengthen the durability of the nanofiber which could be used as air filters. The CS-TFA and CS-TFA/DCM nanofiber diameters were 95.58 ± 39.28 nm or 907.94 ± 290.18 nm, respectively, as measured from the HRSEM images. The CS-PET ...

Applied Sciences, 2021

The accumulation of plastic waste products in the environment has adversely affected wildlife and... more The accumulation of plastic waste products in the environment has adversely affected wildlife and human beings. Common plastics that accumulate in the environment are plastics that are made of polyethylene terephthalate (PET) polymer. PET plastic waste products can be recycled for beneficial use, which would reduce their negative impacts. In this study, modified PET or waste PET (WPET) from plastic bottles was blended with powder commercial 2-(aminomethyl)pyridine (SiAMPy) resin and electrospun into composite nanofibres and applied for Cu2+ adsorption. PET-SiAMPy or WPET-SiAMPy composite nanofibres fibre diameters from the HRSEM images were 90–140 nm and 110–155 nm, respectively. In batch adsorption experiments, PET-SiAMPy or WPET-SiAMPy composite nanofibres achieved Cu2+ adsorption equilibrium within 60 secs of contact time with 0.98 mmol/g (89.87%) or 1.24 mmol/g (96.04%) Cu2+ adsorption capacity. The Cu2+ complex formation rate (k) with WPET-SiAMPy was 0.0888 with the mole ratio ...

Colloid and Polymer Science, 2021

In this study, silver nanoparticles (AgNPs) were immobilized on the surface of polyethylene terep... more In this study, silver nanoparticles (AgNPs) were immobilized on the surface of polyethylene terephthalate (PET) membrane using diethylenetriamine (DETA) as a chemical linker. The molecule of DETA was attached to the surface of PET via an amide bond following scission of the polyester ester bond on the PET surface. The AgNPs were immobilized on the surface of diethylenetriamine-modified PET membrane via a silver-nitrogen covalent bond. The silver-coated, DETA-modified and unmodified PET membranes were characterized by Fourier transform infrared (FTIR), x-ray photoelectron spectroscopy (XPS), ulltraviolet-visible spectroscopy (UV-Vis), and scanning electron microscopy (SEM). The results showed that the size of AgNPs also increased with time of immobilization. The percentage of elemental silver also increased with increase in time of immobilization of AgNPs on the surface of DETA-modified PET membrane. The AgNP-coated PET membrane was used as SERS platform to detect acetaminophen in water. The SERS results showed that acetaminophen molecules could be detected with high Raman scattering intensity arising from adsorption of acetaminophen molecules on the silver nanoparticles of the SERS platform.

Journal of Environmental Chemical Engineering, 2021

Abstract The big advantage of functionalised nanofibers is their fast adsorption kinetics and con... more Abstract The big advantage of functionalised nanofibers is their fast adsorption kinetics and considerable interest is currently devoted to developing nanofiber adsorbents for rapid sorption of metal ions. Polyethylene terephthalate nanofibers (PET-nf) functionalised with diglycolic anhydride ligand (PET-DGAnf) were prepared using a simple one-step reaction route. The surface characterisation of the synthesised PET-DGAnf adsorbents was performed using HR-SEM, XRD, TGA, BET, WCA and ATR-FTIR. The electrospinning optimisation was described by response surface methodology (RSM) and the collector distance was statistically significant to describe the production of nanofibers at optimum conditions. The average fiber diameter and the RSM analysis predicted values (113.6 nm) were in good agreement. Experiments in batch mode investigated factors such as the role of pH, solution concentration and contact time to evaluate their application for neodymium (Nd3+) and cerium (Ce3+) adsorption. The maximum PET-DGAnf adsorption capacity using the Langmuir model equation was 135.9 and 123.7 mg/g for Ce3+ and Nd3+ respectively and the equilibrium adsorption was attained within 5 min. The PET-DGAnf demonstrated good selectivity for Ce3+ in the presence of contending ions like Sr2+, Ni2+ and Co2+ ions after four successive adsorption and desorption assessments, and the desorption rate of Ce3+ and Nd3+ was maintained at more than 90% of their adsorption abilities. The PET-DGAnf nanofibers may provide a promising adsorbent for metal adsorption based on their fast binding kinetics and the high selectivity in recovering REE ions from aqueous solution.

Proceedings, 2020

The plastic and metal pollution accumulating in the marine environment has given many researchers... more The plastic and metal pollution accumulating in the marine environment has given many researchers motivation to investigate and provide solutions to this problem. [...]

Materials Science and Engineering: B, 2021

Polyacrylonitrile and its TiO 2 composites were electrospun into nanofibers in N, N'-dimethylform... more Polyacrylonitrile and its TiO 2 composites were electrospun into nanofibers in N, N'-dimethylformamide for photocatalysis and antifouling experiments. The resultants nanofibers were characterized using field emission scanning microscope, Fourier transform infrared spectroscopy, x-ray diffraction, x-ray photoelectron spectroscopy and contact angle analyses. Fourier transform infrared spectroscopy confirmed the formation of polyacrylonitrile-TiO 2 composite nanofibers with their diameter ranging from 10 to 340 nm. The x-ray photoelectron spectroscopy results indicate the formation of O-TiC bonds on polyacrylonitrile-TiO 2 matrix. polyacrylonitrile-TiO 2 and polyacrylonitrile nanofiber surfaces showed superhydrophobicity with water contact angle of 155 ± 1 and 154 ± 1, respectively at 120 s. The photocatalytic properties of polyacrylonitrile nanofibers and polyacrylonitrile-TiO 2 nanofibers were investigated under a simulated visible light source of 1000 W/m 2 using methylene blue. About 90% of methylene blue was degraded within 3 h of exposure using polyacrylonitrile-TiO 2 nanofibers while 55% methylene blue degradation was achieved for polyacrylonitrile nanofibers. Photoluminescence experiment conducted on both materials showed that polyacrylonitrile-TiO 2 could produce OH radicals 10-fold compared to polyacrylonitrile nanofibers. Antimicrobial tests were conducted using E. coli and Bacillus sp. The results showed that only polyacrylonitrile-TiO 2 under visible light hindered the growth of these bacteria with a greater effect on the Gram-positive bacterium, Bacillus sp. The photo-degradation and microbial growth inhibition properties of polyacrylonitrile-TiO 2 showed that the material could be used as an antifouling material under visible light.

Proceedings, 2020

Modifying nanofibers with specific ligands for metal chelation or adsorption purpose is no [...]

Proceedings, 2019

Functionalized nanofibers made by electrospinning technique. [...]

Separation and Purification Technology, 2019

Highly selective and stable ligands with fast kinetics for rare earth element extraction are not ... more Highly selective and stable ligands with fast kinetics for rare earth element extraction are not well developed. Durable attachment of ligands to the support would make regeneration possible. Polystyrene nanofiber supports (PS-nF) were prepared using the electrospinning method. Thereafter, PS-nf were chemically modified with diglycolic anhydride (DGA) to produce novel electrospun polystyrene diglycolic acid nanofiber (PS-DGAnf) adsorbents. The immobilisation reaction proceeded via an electrophilic aromatic substitution of the ligand onto the PS nanofiber. The maximum gravimetric loading of DGA on PS nanofiber was 0.827 g g-1. The unmodified and modified nanofibers were characterised by ATR-FTIR, HR-SEM, BET and TGA. After optimising pH, time and concentration, the equilibrium adsorption and binding kinetics of cerium (Ce3+) and neodymium (Nd3+) ions on the nanofibers surface were examined at pH 6. The adsorption capacity of PS-DGAnf for Ce3+ and Nd3+ at pH 6.0 was 152.5 mg g-1 (1.09 mmol/g) and 146.2 mg g-1 (1.01 mmol/g) respectively. Selectivity of Ce3+ over Ni2+, Co2+ and Sr3+ was also studied at pH 6. The amount of Ce3+ adsorbed even in the presence of interfering ions was 100.3 mg g-1, which was only a little lower than 119.4 mg g-1 obtained in a single ion solution. The rapid adsorption kinetics of Ce3+ and Nd3+ ions were achieved within 15 mins. The desorption and regeneration was carried out with 1 M nitric acid and the developed PS-DGAnf adsorbent could be reused for 4 cycles without any substantial loss to its adsorption abilities.

Materials Today Communications, 2019

A novel composite membrane was obtained by combining the products of ion-tracking and electrospin... more A novel composite membrane was obtained by combining the products of ion-tracking and electrospinning processes. Swift heavy ions generated from a cyclotron were used to irradiate polyethylene terephthalate (PET) polymer film of thickness 23 µm to create latent tracks which were then chemically etched in an alkaline solution, to produce track-etched membrane. Magnetron sputtering was then used to deposite titanium (Ti) on the membrane to produce PET-TM with Ti thickness of ~45 nm. Polyamide 6 nanofibres (PA6-nfs) or polyacrylonitrile nanofibres (PAN-nfs) were directly electrospun upon the Ti coated PET-TM using an electrospinning process. The average fibre diameter of PA6-nfs or PAN-nfs was 52±9.8 nm or 354±40 nm, respectively. The track-etched membrane, the nanofibres and the novel composite membrane were characterised using SEM, TEM, TGA, ATR-FTIR and adsorption/desorption of nitrogen techniques. The results confirmed the fabrication of nanofibre coated track-etched composite membrane.

Journal of Polymers and the Environment, 2019

Among a wide range of technologies available to separate metal ions, adsorption is a major treatm... more Among a wide range of technologies available to separate metal ions, adsorption is a major treatment technique for removing or recovering metals from aqueous solutions. Electrospun nanofiber adsorbents have attracted research consideration due to the distinctive properties such as their high surface area, high porosity and high adsorption capacity which makes nanofibers a good choice for selective metal recovery applications. Thus, the modification of electrospun nanofiber adsorbents by functionalisation with suitable ligands for selective metal extraction is a growing area of scientific research aiming to improve the selectivity of the adsorption process. This study reviews and summarises available information related to the different nanofiber modification processes for increasing adsorption efficiency, functionality and selectivity of modified nanofiber adsorbents as well as improving their durability and stability during use. The surface properties of an adsorbent is an essential control factor for its metal ion adsorption efficiency. The various techniques available for characterisation of specific properties of nanofiber adsorbents are also considered. Lastly, the recovery of the metal ions after adsorption by regenerating adsorbent materials and understanding the kinetics of nanofiber adsorption processes is summarised and recommendations made for further studies in order to address existing weaknesses of these materials.

DESALINATION AND WATER TREATMENT, 2018

The rare-earth elements (REEs) remain very important due to the growing increase in their demand ... more The rare-earth elements (REEs) remain very important due to the growing increase in their demand and for their critical and indispensable use in many high-tech industries today. This growing demand for REEs has led to an increased environmental exposure and water pollution from numerous REEs commercial products and as a result, the recovery of REEs is a significant issue that requires appropriate consideration. There are diverse and various strategic techniques available to remove metal ions from aqueous solutions, but nanofiber adsorbent appears to be quite innovative due to their outstanding characteristics such as cost effectiveness, flexibility, high surface area, porosity, and the portable nature which makes them a better choice for potential adsorbent applications. This review presents a brief view on several typical removal techniques, new developments and applicable examples of the various technologies used for the removal of rare earth elements from water/ wastewater solutions. The review highlights these developments with a particular focus on innovative physicochemical removal processes like adsorption as the process techniques most widely used.

Water, Air, & Soil Pollution, 2016

Removal of toxic metals from aqueous solutions is of high priority in environmental chemistry. Mo... more Removal of toxic metals from aqueous solutions is of high priority in environmental chemistry. Most of the available techniques for this task are considered expensive; however, the adsorption process has been considered the easiest and the cheapest way of removing toxic metals from aqueous solution. The performance of adsorption setup largely depends on the characteristic of adsorbents. One of these characteristic is availability of large surface area. The more the available sites for chelation, the more the amount of metals removed. Therefore, the production of materials of nanoscale is expedient for adsorption purposes. Electrospinning process is one of the technologies that have been employed to produce polyacrylonitrile nanofibres (PAN-nfs). Moreover, PAN-nfs surfaces have also been chemically modified so as to introduce chelating groups such as amine, carboxyl, imines, etc. Here we review PAN-nfs as metal ion adsorbent. With characteristics such as high surface area as well as good mechanical strength, modified PAN-nfs are considered good adsorbents and have been used to remove toxic metals such as cadmium, lead, chromium, mercury, uranium, silver and copper in different ion states from their aqueous solutions. The ease of immobilization of metal-specific ligands on PAN-nfs has been of great interest in selective extraction of metal ions from their aqueous solutions. Also, toxic metals adsorbed on modified PAN-nfs can be recovered through desorption process using acids or bases of various concentrations.

Journal of Polymers and the Environment, 2016

In recent decades, electrospun nanofibres have been applied to different potential fields such as... more In recent decades, electrospun nanofibres have been applied to different potential fields such as sensor devices, tissue engineering scaffolds, wound dressing, filtration, drug delivery, etc. and significant review papers have been published in these fields. However, the use of electrospun nanofibres in metal ion adsorption is emerging and comparatively innovative. Nanofibre materials hold great potential in advancing the growth of metallurgical technologies and progress for the separation of metallic ions from various sources. The physico-chemical removal processes of adsorption use nanofibres due to their large surface area to volume ratio and the availability of a wide variety of chemical and morphological modification methods. In this review paper, research and developments related to electrospun polymer nanofibre for metal ion removal is presented. The review highlights the emerging and increasing use of electrospun nanofibres for metal ion adsorption especially for hazardous metals. Fundamental understanding of the electrospinning fabrication process, working parameters as they affect fibre morphologies, solvents and polymers used in electrospinning is discussed. This work summarizes the current status of process technique development and ideas in the research and use of electrospun nanofibres in heavy metal ion adsorption to address environmental problems from contaminated water.

Polymer Bulletin, 2016

Polyacrylonitrile nanofibers (PAN-nfs) are one of t he most studied nanofibres because of their e... more Polyacrylonitrile nanofibers (PAN-nfs) are one of t he most studied nanofibres because of their excellent characteristics, such as good mechanical strength, chemical resistance, and good thermal stability. Due to the easy dissolution in polar organic solvents, PAN-nfs are mostly produced via electrospinning technique. The electrospun PAN-nfs surfaces are relatively inactive and hydrophobic, and, therefore, hinder some potential applications; however, chemical surface modification reactions, such as amination, reduction, hydrolysis, and amidoximation, have been carried out on them. These reactions bring about functional groups, such as amine, hydroxyl, carboxylic, imine etc, to the surface PAN-nfs and invariably make their surfaces active and hydrophilic. The surface-modified PAN-nfs have been used as supports for organic compounds, enzymes, and antibodies in biological studies. They have also been used for immobilization of various organic ligands for adsorption of metal ions in water. Furthermore, because of their ability to complex metal ions, several surface-modified PAN-nfs have also been used as supports for transition metal catalysts in Fenton's chemistry.

Materials Today Chemistry, 2021

The development of next-generation adsorption, separation, and filtration materials is growing wi... more The development of next-generation adsorption, separation, and filtration materials is growing with an increased research focus on polymer composites. In this study, a novel blend of chitosan (CS) and polyethylene oxide (PEO) nanofiber mats was electrospun on titanium (Ti)-coated polyethylene terephthalate (PET) track-etched membranes (TMs) with after-treatment by glutaraldehyde in the vapor phase for enhancing the nanofiber stability by crosslinking. The prepared composite, titanium-coated track-etched nanofiber membrane (TTM-CPnf) was characterized by Fourier transform infra-red (FTIR), water contact angle, and scanning electron microscopy (SEM) analyses. Smooth and uniform CS nanofibers with an average fiber diameter of 156.55 nm were produced from a 70/30 CS/PEO blend solution prepared from 92 wt. % acetic acid and electrospun at 15 cm needle to collector distance with 0.5 mL/h flow rate and an applied voltage of 30 kV on the TTM-CPnf. Short (15 min) and long (72 h)-term solubility tests showed that after 3 h, crosslinked nanofibers were stable in acidic (pH ¼ 3), basic (pH ¼ 13), and neutral (pH ¼ 7) solutions. The crosslinked TTM-CPnf material was biocompatible based on the low mortality of freshwater crustaceans Daphnia magna. The composite membranes comprised of electrospun nanofiber and TMs proved to be biocompatible and may thus be suitable for diverse applications such as dual adsorptionefiltration systems in water treatment.

Materials Science Forum

Properties of poly(ethylene terephthalate) track membrane (PET TM) exposed to an allyl alcohol ra... more Properties of poly(ethylene terephthalate) track membrane (PET TM) exposed to an allyl alcohol radiofrequency plasma after pre-activation its surface in an oxygen plasma were studied. The influence of plasma treatment conditions on basic membrane characteristics, i.e. pore size and shape, wettability, and water permeability, was studied. It has been shown that the plasma treatment of membrane can significantly improve its performance characteristics.

Polymers

Textile single-use products are dominantly used for hygiene and personal care, many of which are ... more Textile single-use products are dominantly used for hygiene and personal care, many of which are non-biodegradable and are frequently discarded into sewerage systems, thus causing blockages. Thus, there is a need to move towards water-soluble textiles. This research study focuses on transforming or repurposing biomass material and synthetic reusable waste plastic materials to improve waste. Chitosan (CS) nanofibers could be used in single-use nonwoven fabric or biodegradable tissues, as the water-soluble properties of chitosan nanofibers make them the perfect material for single-use applications. Furthermore, CS was blended with polyethylene terephthalate (PET) polymer and PET-based waste plastic (CS-WPET) to slow the CS nanofibers’ water degradability and strengthen the durability of the nanofiber which could be used as air filters. The CS-TFA and CS-TFA/DCM nanofiber diameters were 95.58 ± 39.28 nm or 907.94 ± 290.18 nm, respectively, as measured from the HRSEM images. The CS-PET ...

Applied Sciences, 2021

The accumulation of plastic waste products in the environment has adversely affected wildlife and... more The accumulation of plastic waste products in the environment has adversely affected wildlife and human beings. Common plastics that accumulate in the environment are plastics that are made of polyethylene terephthalate (PET) polymer. PET plastic waste products can be recycled for beneficial use, which would reduce their negative impacts. In this study, modified PET or waste PET (WPET) from plastic bottles was blended with powder commercial 2-(aminomethyl)pyridine (SiAMPy) resin and electrospun into composite nanofibres and applied for Cu2+ adsorption. PET-SiAMPy or WPET-SiAMPy composite nanofibres fibre diameters from the HRSEM images were 90–140 nm and 110–155 nm, respectively. In batch adsorption experiments, PET-SiAMPy or WPET-SiAMPy composite nanofibres achieved Cu2+ adsorption equilibrium within 60 secs of contact time with 0.98 mmol/g (89.87%) or 1.24 mmol/g (96.04%) Cu2+ adsorption capacity. The Cu2+ complex formation rate (k) with WPET-SiAMPy was 0.0888 with the mole ratio ...

Colloid and Polymer Science, 2021

In this study, silver nanoparticles (AgNPs) were immobilized on the surface of polyethylene terep... more In this study, silver nanoparticles (AgNPs) were immobilized on the surface of polyethylene terephthalate (PET) membrane using diethylenetriamine (DETA) as a chemical linker. The molecule of DETA was attached to the surface of PET via an amide bond following scission of the polyester ester bond on the PET surface. The AgNPs were immobilized on the surface of diethylenetriamine-modified PET membrane via a silver-nitrogen covalent bond. The silver-coated, DETA-modified and unmodified PET membranes were characterized by Fourier transform infrared (FTIR), x-ray photoelectron spectroscopy (XPS), ulltraviolet-visible spectroscopy (UV-Vis), and scanning electron microscopy (SEM). The results showed that the size of AgNPs also increased with time of immobilization. The percentage of elemental silver also increased with increase in time of immobilization of AgNPs on the surface of DETA-modified PET membrane. The AgNP-coated PET membrane was used as SERS platform to detect acetaminophen in water. The SERS results showed that acetaminophen molecules could be detected with high Raman scattering intensity arising from adsorption of acetaminophen molecules on the silver nanoparticles of the SERS platform.

Journal of Environmental Chemical Engineering, 2021

Abstract The big advantage of functionalised nanofibers is their fast adsorption kinetics and con... more Abstract The big advantage of functionalised nanofibers is their fast adsorption kinetics and considerable interest is currently devoted to developing nanofiber adsorbents for rapid sorption of metal ions. Polyethylene terephthalate nanofibers (PET-nf) functionalised with diglycolic anhydride ligand (PET-DGAnf) were prepared using a simple one-step reaction route. The surface characterisation of the synthesised PET-DGAnf adsorbents was performed using HR-SEM, XRD, TGA, BET, WCA and ATR-FTIR. The electrospinning optimisation was described by response surface methodology (RSM) and the collector distance was statistically significant to describe the production of nanofibers at optimum conditions. The average fiber diameter and the RSM analysis predicted values (113.6 nm) were in good agreement. Experiments in batch mode investigated factors such as the role of pH, solution concentration and contact time to evaluate their application for neodymium (Nd3+) and cerium (Ce3+) adsorption. The maximum PET-DGAnf adsorption capacity using the Langmuir model equation was 135.9 and 123.7 mg/g for Ce3+ and Nd3+ respectively and the equilibrium adsorption was attained within 5 min. The PET-DGAnf demonstrated good selectivity for Ce3+ in the presence of contending ions like Sr2+, Ni2+ and Co2+ ions after four successive adsorption and desorption assessments, and the desorption rate of Ce3+ and Nd3+ was maintained at more than 90% of their adsorption abilities. The PET-DGAnf nanofibers may provide a promising adsorbent for metal adsorption based on their fast binding kinetics and the high selectivity in recovering REE ions from aqueous solution.

Proceedings, 2020

The plastic and metal pollution accumulating in the marine environment has given many researchers... more The plastic and metal pollution accumulating in the marine environment has given many researchers motivation to investigate and provide solutions to this problem. [...]

Materials Science and Engineering: B, 2021

Polyacrylonitrile and its TiO 2 composites were electrospun into nanofibers in N, N'-dimethylform... more Polyacrylonitrile and its TiO 2 composites were electrospun into nanofibers in N, N'-dimethylformamide for photocatalysis and antifouling experiments. The resultants nanofibers were characterized using field emission scanning microscope, Fourier transform infrared spectroscopy, x-ray diffraction, x-ray photoelectron spectroscopy and contact angle analyses. Fourier transform infrared spectroscopy confirmed the formation of polyacrylonitrile-TiO 2 composite nanofibers with their diameter ranging from 10 to 340 nm. The x-ray photoelectron spectroscopy results indicate the formation of O-TiC bonds on polyacrylonitrile-TiO 2 matrix. polyacrylonitrile-TiO 2 and polyacrylonitrile nanofiber surfaces showed superhydrophobicity with water contact angle of 155 ± 1 and 154 ± 1, respectively at 120 s. The photocatalytic properties of polyacrylonitrile nanofibers and polyacrylonitrile-TiO 2 nanofibers were investigated under a simulated visible light source of 1000 W/m 2 using methylene blue. About 90% of methylene blue was degraded within 3 h of exposure using polyacrylonitrile-TiO 2 nanofibers while 55% methylene blue degradation was achieved for polyacrylonitrile nanofibers. Photoluminescence experiment conducted on both materials showed that polyacrylonitrile-TiO 2 could produce OH radicals 10-fold compared to polyacrylonitrile nanofibers. Antimicrobial tests were conducted using E. coli and Bacillus sp. The results showed that only polyacrylonitrile-TiO 2 under visible light hindered the growth of these bacteria with a greater effect on the Gram-positive bacterium, Bacillus sp. The photo-degradation and microbial growth inhibition properties of polyacrylonitrile-TiO 2 showed that the material could be used as an antifouling material under visible light.

Proceedings, 2020

Modifying nanofibers with specific ligands for metal chelation or adsorption purpose is no [...]

Proceedings, 2019

Functionalized nanofibers made by electrospinning technique. [...]

Separation and Purification Technology, 2019

Highly selective and stable ligands with fast kinetics for rare earth element extraction are not ... more Highly selective and stable ligands with fast kinetics for rare earth element extraction are not well developed. Durable attachment of ligands to the support would make regeneration possible. Polystyrene nanofiber supports (PS-nF) were prepared using the electrospinning method. Thereafter, PS-nf were chemically modified with diglycolic anhydride (DGA) to produce novel electrospun polystyrene diglycolic acid nanofiber (PS-DGAnf) adsorbents. The immobilisation reaction proceeded via an electrophilic aromatic substitution of the ligand onto the PS nanofiber. The maximum gravimetric loading of DGA on PS nanofiber was 0.827 g g-1. The unmodified and modified nanofibers were characterised by ATR-FTIR, HR-SEM, BET and TGA. After optimising pH, time and concentration, the equilibrium adsorption and binding kinetics of cerium (Ce3+) and neodymium (Nd3+) ions on the nanofibers surface were examined at pH 6. The adsorption capacity of PS-DGAnf for Ce3+ and Nd3+ at pH 6.0 was 152.5 mg g-1 (1.09 mmol/g) and 146.2 mg g-1 (1.01 mmol/g) respectively. Selectivity of Ce3+ over Ni2+, Co2+ and Sr3+ was also studied at pH 6. The amount of Ce3+ adsorbed even in the presence of interfering ions was 100.3 mg g-1, which was only a little lower than 119.4 mg g-1 obtained in a single ion solution. The rapid adsorption kinetics of Ce3+ and Nd3+ ions were achieved within 15 mins. The desorption and regeneration was carried out with 1 M nitric acid and the developed PS-DGAnf adsorbent could be reused for 4 cycles without any substantial loss to its adsorption abilities.

Materials Today Communications, 2019

A novel composite membrane was obtained by combining the products of ion-tracking and electrospin... more A novel composite membrane was obtained by combining the products of ion-tracking and electrospinning processes. Swift heavy ions generated from a cyclotron were used to irradiate polyethylene terephthalate (PET) polymer film of thickness 23 µm to create latent tracks which were then chemically etched in an alkaline solution, to produce track-etched membrane. Magnetron sputtering was then used to deposite titanium (Ti) on the membrane to produce PET-TM with Ti thickness of ~45 nm. Polyamide 6 nanofibres (PA6-nfs) or polyacrylonitrile nanofibres (PAN-nfs) were directly electrospun upon the Ti coated PET-TM using an electrospinning process. The average fibre diameter of PA6-nfs or PAN-nfs was 52±9.8 nm or 354±40 nm, respectively. The track-etched membrane, the nanofibres and the novel composite membrane were characterised using SEM, TEM, TGA, ATR-FTIR and adsorption/desorption of nitrogen techniques. The results confirmed the fabrication of nanofibre coated track-etched composite membrane.

Journal of Polymers and the Environment, 2019

Among a wide range of technologies available to separate metal ions, adsorption is a major treatm... more Among a wide range of technologies available to separate metal ions, adsorption is a major treatment technique for removing or recovering metals from aqueous solutions. Electrospun nanofiber adsorbents have attracted research consideration due to the distinctive properties such as their high surface area, high porosity and high adsorption capacity which makes nanofibers a good choice for selective metal recovery applications. Thus, the modification of electrospun nanofiber adsorbents by functionalisation with suitable ligands for selective metal extraction is a growing area of scientific research aiming to improve the selectivity of the adsorption process. This study reviews and summarises available information related to the different nanofiber modification processes for increasing adsorption efficiency, functionality and selectivity of modified nanofiber adsorbents as well as improving their durability and stability during use. The surface properties of an adsorbent is an essential control factor for its metal ion adsorption efficiency. The various techniques available for characterisation of specific properties of nanofiber adsorbents are also considered. Lastly, the recovery of the metal ions after adsorption by regenerating adsorbent materials and understanding the kinetics of nanofiber adsorption processes is summarised and recommendations made for further studies in order to address existing weaknesses of these materials.

DESALINATION AND WATER TREATMENT, 2018

The rare-earth elements (REEs) remain very important due to the growing increase in their demand ... more The rare-earth elements (REEs) remain very important due to the growing increase in their demand and for their critical and indispensable use in many high-tech industries today. This growing demand for REEs has led to an increased environmental exposure and water pollution from numerous REEs commercial products and as a result, the recovery of REEs is a significant issue that requires appropriate consideration. There are diverse and various strategic techniques available to remove metal ions from aqueous solutions, but nanofiber adsorbent appears to be quite innovative due to their outstanding characteristics such as cost effectiveness, flexibility, high surface area, porosity, and the portable nature which makes them a better choice for potential adsorbent applications. This review presents a brief view on several typical removal techniques, new developments and applicable examples of the various technologies used for the removal of rare earth elements from water/ wastewater solutions. The review highlights these developments with a particular focus on innovative physicochemical removal processes like adsorption as the process techniques most widely used.

Water, Air, & Soil Pollution, 2016

Removal of toxic metals from aqueous solutions is of high priority in environmental chemistry. Mo... more Removal of toxic metals from aqueous solutions is of high priority in environmental chemistry. Most of the available techniques for this task are considered expensive; however, the adsorption process has been considered the easiest and the cheapest way of removing toxic metals from aqueous solution. The performance of adsorption setup largely depends on the characteristic of adsorbents. One of these characteristic is availability of large surface area. The more the available sites for chelation, the more the amount of metals removed. Therefore, the production of materials of nanoscale is expedient for adsorption purposes. Electrospinning process is one of the technologies that have been employed to produce polyacrylonitrile nanofibres (PAN-nfs). Moreover, PAN-nfs surfaces have also been chemically modified so as to introduce chelating groups such as amine, carboxyl, imines, etc. Here we review PAN-nfs as metal ion adsorbent. With characteristics such as high surface area as well as good mechanical strength, modified PAN-nfs are considered good adsorbents and have been used to remove toxic metals such as cadmium, lead, chromium, mercury, uranium, silver and copper in different ion states from their aqueous solutions. The ease of immobilization of metal-specific ligands on PAN-nfs has been of great interest in selective extraction of metal ions from their aqueous solutions. Also, toxic metals adsorbed on modified PAN-nfs can be recovered through desorption process using acids or bases of various concentrations.

Journal of Polymers and the Environment, 2016

In recent decades, electrospun nanofibres have been applied to different potential fields such as... more In recent decades, electrospun nanofibres have been applied to different potential fields such as sensor devices, tissue engineering scaffolds, wound dressing, filtration, drug delivery, etc. and significant review papers have been published in these fields. However, the use of electrospun nanofibres in metal ion adsorption is emerging and comparatively innovative. Nanofibre materials hold great potential in advancing the growth of metallurgical technologies and progress for the separation of metallic ions from various sources. The physico-chemical removal processes of adsorption use nanofibres due to their large surface area to volume ratio and the availability of a wide variety of chemical and morphological modification methods. In this review paper, research and developments related to electrospun polymer nanofibre for metal ion removal is presented. The review highlights the emerging and increasing use of electrospun nanofibres for metal ion adsorption especially for hazardous metals. Fundamental understanding of the electrospinning fabrication process, working parameters as they affect fibre morphologies, solvents and polymers used in electrospinning is discussed. This work summarizes the current status of process technique development and ideas in the research and use of electrospun nanofibres in heavy metal ion adsorption to address environmental problems from contaminated water.

Polymer Bulletin, 2016

Polyacrylonitrile nanofibers (PAN-nfs) are one of t he most studied nanofibres because of their e... more Polyacrylonitrile nanofibers (PAN-nfs) are one of t he most studied nanofibres because of their excellent characteristics, such as good mechanical strength, chemical resistance, and good thermal stability. Due to the easy dissolution in polar organic solvents, PAN-nfs are mostly produced via electrospinning technique. The electrospun PAN-nfs surfaces are relatively inactive and hydrophobic, and, therefore, hinder some potential applications; however, chemical surface modification reactions, such as amination, reduction, hydrolysis, and amidoximation, have been carried out on them. These reactions bring about functional groups, such as amine, hydroxyl, carboxylic, imine etc, to the surface PAN-nfs and invariably make their surfaces active and hydrophilic. The surface-modified PAN-nfs have been used as supports for organic compounds, enzymes, and antibodies in biological studies. They have also been used for immobilization of various organic ligands for adsorption of metal ions in water. Furthermore, because of their ability to complex metal ions, several surface-modified PAN-nfs have also been used as supports for transition metal catalysts in Fenton's chemistry.

Materials Today Chemistry, 2021

The development of next-generation adsorption, separation, and filtration materials is growing wi... more The development of next-generation adsorption, separation, and filtration materials is growing with an increased research focus on polymer composites. In this study, a novel blend of chitosan (CS) and polyethylene oxide (PEO) nanofiber mats was electrospun on titanium (Ti)-coated polyethylene terephthalate (PET) track-etched membranes (TMs) with after-treatment by glutaraldehyde in the vapor phase for enhancing the nanofiber stability by crosslinking. The prepared composite, titanium-coated track-etched nanofiber membrane (TTM-CPnf) was characterized by Fourier transform infra-red (FTIR), water contact angle, and scanning electron microscopy (SEM) analyses. Smooth and uniform CS nanofibers with an average fiber diameter of 156.55 nm were produced from a 70/30 CS/PEO blend solution prepared from 92 wt. % acetic acid and electrospun at 15 cm needle to collector distance with 0.5 mL/h flow rate and an applied voltage of 30 kV on the TTM-CPnf. Short (15 min) and long (72 h)-term solubility tests showed that after 3 h, crosslinked nanofibers were stable in acidic (pH ¼ 3), basic (pH ¼ 13), and neutral (pH ¼ 7) solutions. The crosslinked TTM-CPnf material was biocompatible based on the low mortality of freshwater crustaceans Daphnia magna. The composite membranes comprised of electrospun nanofiber and TMs proved to be biocompatible and may thus be suitable for diverse applications such as dual adsorptionefiltration systems in water treatment.

Materials Science Forum

Properties of poly(ethylene terephthalate) track membrane (PET TM) exposed to an allyl alcohol ra... more Properties of poly(ethylene terephthalate) track membrane (PET TM) exposed to an allyl alcohol radiofrequency plasma after pre-activation its surface in an oxygen plasma were studied. The influence of plasma treatment conditions on basic membrane characteristics, i.e. pore size and shape, wettability, and water permeability, was studied. It has been shown that the plasma treatment of membrane can significantly improve its performance characteristics.