Usman Ali Rana

Dissolution of feather keratin in ionic liquids

Keratin from various livestock industries is currently a waste material that has potential as a source of polyamide polymers that could replace fossil fuel derived materials if processing methods can be developed. In this work we have investigated methods for the dissolution and regeneration of keratin. Dissolution of keratin (from turkey feather) in ionic liquids was conducted under nitrogen at 130 °C for 10 hours. It was found that [BMIM]Cl, [AMIM]Cl and [choline][thioglycolate] could dissolve turkey feather keratin without addition of solvent or other chemicals. A significant percentage of solubility was obtained, up to 45% by weight. A water insoluble fraction was recovered by addition of water to the solution (∼50%). The structure and properties of this regenerated, water insoluble fraction were investigated. Compared to the starting material, the regenerated keratin shows structural changes rather than chemical changes within the polypeptide chains. The remaining fraction, consisting of water soluble fragments, was characterised by gel electrophoresis.

Dissolution and regeneration of wool keratin in ionic liquids

Wool keratin, a natural biopolymer, is potentially an important renewable source of raw materials for the polyamide plastics industry. Large quantities of non-spinnable and short fibers of wool are discarded globally and hence are available as low value waste materials. In this study, we have investigated different solvents, including ionic liquids and deep eutectic mixtures, for the dissolution and processing of wool. The results show that substantial dissolution of wool (up to 475 mg wool per gram of solvent) can be obtained in the 1-allyl-3-methylimidazolium dicyanamide [AMIM][dca] ionic liquid at 130 °C. Our studies also indicated enhanced dissolution (an additional 50–100 mg g−1) of wool upon the addition of a reducing agent to the ionic liquids. Water insoluble fractions (20–40%) were obtained on the addition of water to the dissolved wool. This regenerated fraction was characterized for structural and chemical changes and found to contain a larger fraction of β-sheets and random coils than the starting material. The water soluble fraction was characterised and the results indicated the presence of fragments of low molecular weight polypeptide chains.

Protic ionic liquids based on phosphonium cations: comparison with ammonium analogues

Novel protic ionic liquids (PILs) based on a tributyl phosphonium cation have been synthesised and characterised, revealing that the phosphonium based ILs show high thermal stability, high ionic conductivity and facile proton reduction compared to the corresponding ammonium based ILs.

Micelles as Soil and Water Decontamination Agents

Contaminated soil and water pose a serious threat to human health and ecosystem. For the treatment of industrial effluents or minimizing their detrimental effects, preventive and remedial approaches must be adopted prior to the occurrence of any severe environmental, health, or safety hazard. Conventional treatment methods of wastewater are insufficient, complicated, and expensive. Therefore, a method that could use environmentally friendly surfactants for the simultaneous removal of both organic and inorganic contaminants from wastewater is deemed a smart approach. Surfactants containing potential donor ligands can coordinate with metal ions, and thus such compounds can be used for the removal of toxic metals and organometallic compounds from aqueous systems. Surfactants form host-guest complexes with the hydrophobic contaminants of water and soil by a mechanism involving the encapsulation of hydrophobes into the self-assembled aggregates (micelles) of surfactants. However, because undefined amounts of surfactants may be released into the aqueous systems, attention must be paid to their own environmental risks as well. Moreover, surfactant remediation methods must be carefully analyzed in the laboratory before field implementation. The use of biosurfactants is the best choice for the removal of water toxins as such surfactants are associated with the characteristics of biodegradability, versatility, recovery, and reuse. This Review is focused on the currently employed surfactant-based soil and wastewater treatment technologies owing to their critical role in the implementation of certain solutions for controlling pollution level, which is necessary to protect human health and ensure the quality standard of the aquatic environment.

Synthesis of hierarchical porous spinel nickel cobaltite nanoflakes for high performance electrochemical energy storage supercapacitors

Hierarchical porous spinel nickel cobaltite (NiCo2O4) nanoflakes synthesized through a cost-effective and scalable chemical precipitation method exhibited high specific capacitance (1270 F g−1), excellent rate capability (81% capacity retention at 10 A g−1) and cycling stability (only 4.8% loss after 5000 cycles).

Plastic crystal phases with high proton conductivity

The addition of up to 4 mol% of the strong acids, trifluoromethane sulfonic acid (TfOH) and bis-trifluoromethanesulfonyl imide [HN(Tf)2], to the organic ionic plastic crystal (OIPC) [Choline][DHP] has been shown to dramatically increase the ionic conductivity by up to three orders of magnitude whilst still retaining the crystalline structure of the OIPC matrix. This enhanced proton diffusivity led to a significant proton reduction reaction in the electrochemical measurements. Powder XRD and DSC thermal analyses strongly suggest that these mixtures are single phase, crystalline materials. The work here also confirms that an increase in TfOH acid concentration (8 mol% and 12 mol%) results in a higher content of the amorphous phase as previously observed for the H3PO4/[Choline][DHP] system.

In situ hydrogenation of molybdenum oxide nanowires for enhanced supercapacitors

In situ hydrogenation of orthorhombic molybdenum trioxide (α-MoO3) nanowires has been achieved on a large scale by introducing alcohol during the hydrothermal synthesis for electrochemical energy storage supercapacitor devices. The hydrogenated molybdenum trioxide (HxMoO3) nanowires yield a specific capacitance of 168 F g−1 at 0.5 A g−1 and maintain 108 F g−1 at 10 A g−1, which is 36-fold higher than the capacitance obtained from pristine MoO3 nanowires at the same conditions. The electrochemical devices made with HxMoO3 nanowires exhibit excellent cycling stability by retaining 97% of their capacitance after 3000 cycles due to an enhanced electronic conductivity and increased density of hydroxyl groups on the surface of the MoO3 nanowires.

Proton transport behaviour and molecular dynamics in the guanidinium triflate solid and its mixtures with triflic acid

Knowledge of the proton transport behaviour in electrolyte materials is crucial for designing and developing novel solid electrolytes for electrochemical device applications such as fuel cells or batteries. In the present work, high proton conductivity (approximately 10−3 S cm−1) was observed in the triflic acid (HTf) containing guanidinium triflate (GTf) composites. The proton transport mechanism in the composite was elucidated by comparing the diffusion coefficients obtained from NMR and conductivity measurements. Several orders of magnitude enhancement of conductivity is observed upon addition of HTf to the organic solid, and this appears to follow percolation behaviour with a percolation threshold of approximately 2% HTf. The data support a structural diffusion (or Grotthuss) mechanism of proton transport with a calculated Haven ratio significantly less than unity. 13C SUPER and 14N overtone NMR experiments were used to study the mobility and symmetry of the triflate anion and guanidinium cation respectively at a molecular level. The former experiment shows that the CF3 group in the anion displays fast and isotropic motion at room temperature. In contrast to the high mobility of the anion group, the 14N overtone experiments indicate that the guanidinium cation is static in both the pure and the acid-containing GTf samples at room temperature. It is anticipated that these solid-state NMR techniques may be also applied to other organic solid state electrolyte materials to achieve a better understanding of their transport mechanisms and molecular dynamics.

Exploration of a library of triazolothiadiazole and triazolothiadiazine compounds as a highly potent and selective family of cholinesterase and monoamine oxidase inhibitors: design, synthesis, X-ray diffraction analysis and molecular docking studies

There is a high demand for the collection of small organic molecules (especially N-heterocycles) with diversity and complexity in the process of drug discovery. This need for privileged scaffolds in medicinal research gives an impetus for the development of nitrogen-containing compounds which are widely encountered in natural products, drugs and pharmaceutically active compounds. In this context, a diverse library of new triazolothiadiazole (4a–l) and triazolothiadiazine (5a–p) compounds was designed, synthesized and evaluated as potent and selective inhibitors of electric eel acetylcholinesterase (EeAChE) and horse serum butyrylcholinesterase (hBChE) by Ellmans method using neostigmine and donepezil as standard inhibitors. Among the screened triazolothiadiazoles, 4j emerged as a lead candidate showing the highest inhibition with an outstanding IC50 value of 0.117 ± 0.007 μM against AChE, which is ∼139-fold greater inhibitory efficacy as compared to neostigmine, whereas 4k displayed ∼506-fold strong inhibition with IC50 of 0.056 ± 0.001 μM against BChE. In the triazolothiadiazine series, 5j and 5e depicted a clear selectivity towards EeAChE with IC50 values of 0.065 ± 0.005 and 0.075 ± 0.001 μM, respectively, which are ∼250- and ∼218-fold stronger inhibition as compared to neostigmine (IC50 = 16.3 ± 1.12 μM). In addition, the synthesized compounds were also tested for their monoamine oxidase (MAO-A and MAO-B) inhibition, where 4a from the triazolothiadiazole series delivered the highest potency against MAO-A with an IC50 value of 0.11 ± 0.005 μM which is ∼33-fold higher inhibition as compared to the standard inhibitor, clorgyline (IC50 = 3.64 ± 0.012 μM), whereas compound 5c from the triazolothiadiazine series turned out to be a lead inhibitor with an IC50 value of 0.011 ± 0.001 μM which is ∼330-fold stronger inhibition. Moreover, compounds 4b (triazolothiadiazole series) and 5o (triazolothiadiazine series) were identified as lead inhibitors against MAO-B. Molecular modelling studies were performed against human AChE and BChE to observe the binding site interactions of these compounds.

Heat treatment of electrodeposited NiO films for improved catalytic water oxidation

Recognizing the superior electrocatalytic properties of nickel oxide (NiO), we prepared cathodically electrodeposited nickel oxide (NiO) on fluorine doped tin oxide (FTO) glass substrates as binder free electrocatalysts for water oxidation. The electrodeposited nickel oxide film (NiO(ED)) showed remarkable improvement for electrocatalytic water oxidation after heat treatment. In particular, the NiO(ED)-400 catalyst (electrodeposited nickel oxide film heat treated at 400 °C) achieved appreciable current density ∼ 5 mA cm−2 for the oxygen evolution reaction (OER) at the overpotential of 0.45 V vs. RHE. These catalyst films were characterized for structural, morphological, thermal and electrochemical properties, where the results reveal that the dehydration during heat treatment permanently removes the structural water with a concomitant amorphous → crystalline transformation in NiO(ED) films, thereby making them more active catalysts for OER. In parallel investigations, nickel metal was electrodeposited on a stainless steel (SS) substrate, and was subsequently annealed in hot air to produce NiO(HA) films at different temperatures. The NiO(HA) films prepared by this method showed relatively high values of Tafel slopes and corresponding high overpotentials and low currents for OER, when compared to the NiO(ED) films. Hence, simple heat treatment of the cathodically electrodeposited nickel oxide (NiO(ED)) films showed remarkable improvements in their catalytic performances for oxygen evolution reaction, thereby making them efficient electrocatalysts for water oxidation.