Amjed Javid

Production of rhamnolipid surfactant and its application in bioscouring of cotton fabric

In the present study, a biosurfactant was synthesized by using a bacterial strain of Pseudomonas aeruginosa in minimal media provided with n-heptadecane as sole carbon source under shake-flask conditions. The biosurfactant was isolated (by acid precipitation, solvent extraction, and rotary evaporation), purified (by column chromatography and TLC), identified (by FAB-MS, FTIR, and 1D-(1)H NMR), and chemo-physical characterized (by tensiometry). Two principal rhamnolipid congeners were identified as dirhamnolipid RRC10C10 and monorhamnolipid RC10C10 with a CMC of 50mg/L. The biosurfactant, hence produced, was applied in sole and in combination with pectinase in scouring of cotton fabric in contrast to conventional scouring agents of NaOH and anionic surfactant SDS. The scoured cotton fabric was investigated for its weight loss, residual oil and grease, wettability, whiteness, and tensile strength. The results were compared both for conventional and biological approaches. The scouring with biosurfactant plus pectinase was equivalent to or better in efficiency than conventional alkaline scouring. The former process is additionally environmentally friendly and bio-compatible. Scanning electron microscopy of cotton fabric showed that the alkaline scouring deteriorates the fabric texture whereas bioscouring with biosurfactant plus pectinase gently removes hydrophobic impurities from the cotton fabric.

Chitosan microencapsulation of various essential oils to enhance the functional properties of cotton fabric.

Abstract The present study dealt with emulsive fabrication of chitosan microcapsules encapsulating essential oils in the present of bio/surfactant. The size distribution, morphology and stability of microcapsules were examined by using advanced surface characterisation techniques. At cetyl trimethyl ammonium bromide (CTAB) concentration of 330 mg/L, the smallest average size of microcapsules was observed as12.8 μm; whereas with biosurfactant at 50 mg/L, the microcapsules of smallest average size of 7.5 μm were observed. The fabricated microcapsules were applied on a desized, bleached and mercerised cotton fabric by using pad-dry-cure method by using a modified dihydroxy ethylene urea as a cross-linking agent. The cross-linking was confirmed by using scanning electron microscopy and Fourier transform infrared spectroscopy techniques. The antibacterial activity of finished fabric was evaluated using the turbidity estimation method. The stiffness and wrinkle recovery properties of the treated fabric were also investigated by using the standard methods. In general, antibacterial activity of treated fabric increased with the increase in chitosan and essential oil concentrations, whereas stiffness increased with increase in concentration of chitosan but decreased with increase in essential oil concentration.

Role of surface-electrical properties on the cell-viability of carbon thin films grown in nanodomain morphology

Carbon thin films, having a combination of unique physical and chemical properties, exhibit an interesting biocompatibility and biological response to living entities. Here, the carbon films are developed in the morphology form of nano-domains with nanoscale inter-domain separations, tuned by plasma conditions in the facing target magnetron sputtering process. The wettability and surface energy are found to have a close relation to the inter-domain separations. The chemical structure of carbon films exhibited the relative enhancement of sp3 in comparison to sp2 with the increase of domain separations. The cell-viability of these films shows promising results for L929 mouse fibroblast and Saos-2 bone cells, when inter-domain separation is increased. Electrical conductivity and surface energy are identified to play the key role in different time-scales during the cell-proliferation process. The contribution from electrical conductivity is dominant in the beginning of the cultivation, whereas with the passage of time (~3–5 d) the surface energy takes control over conductivity to enhance the cell proliferation.

Nanoscale surface conductivity analysis of plasma sputtered carbon thin films

Understanding of surface conductivity at the nanoscale is very important for surface activities e.g. bio-activity and electronic transportations. In this work, the co-relation of surface properties to surface conductivity has been investigated in carbon films prepared by plasma sputtering. A Field Emission Scanning Electron Microscopy (FE-SEM) study provided evidence of film growth in the form of the nano-domains (NDs). Conductive atomic force microscopy (C-AFM) was used to explore the influence of growth conditions on the local current flow in carbon thin films through the induced current variation across the NDs. It is found that the growth regime of the NDs has a close relation to the power density and the working pressure. The flow of current across the internal area of the ND surface is lower than the boundaries due to the difference of conjugation in sp2 hybridized carbon atoms. The mean current flow through the films as measured by C-AFM is in accordance with the resistivity of the films observed by the van der Pauw method.

Surface Energy in Nanocrystalline Carbon Thin Films: Effect of Size Dependence and Atmospheric Exposure

Surface energy (SE) is the most sensitive and fundamental parameter for governing the interfacial interactions in nanoscale carbon materials. However, on account of the complexities involved of hybridization states and surface bonds, achieved SE values are often less in comparison with their theoretical counterparts and strongly influenced by stability aspects. Here, an advanced facing-target pulsed dc unbalanced magnetron-sputtering process is presented for the synthesis of undoped and H/N-doped nanocrystalline carbon thin films. The time-dependent surface properties of the undoped and H/N-doped nanocrystalline carbon thin films are systematically studied. The advanced plasma process induced the dominant deposition of high-energy neutral carbon species, consequently controlling the intercolumnar spacing of nanodomain morphology and surface anisotropy of electron density. As a result, significantly higher SE values (maximum = 79.24 mJ/m2) are achieved, with a possible window of 79.24-66.5 mJ/m2 by controlling the experimental conditions. The intrinsic (size effects and functionality) and extrinsic factors (atmospheric exposure) are resolved and explained on the basis of size-dependent cohesive energy model and long-range van der Waals interactions between hydrocarbon molecules and the carbon surface. The findings anticipate the enhanced functionality of nanocrystalline carbon thin films in terms of selectivity, sensitivity, and stability.

Development and performance optimization of polyurethane-based multifunctional coatings using Taguchi method:

Inducing multifunctionality is the need of the products used in diverse environments. Here, polyurethane-based water repellent, flame retardant and antibacterial coatings are fabricated on cotton fabrics which sequentially involve the deposition of coating through knife coating, drying and curing of coated fabric. Taguchi design has been used to optimize the parameters for enhanced water repellency, flame retardancy and antibacterial activity. When applied individually, the performance characteristics enhance with the increase in concentration of respective finishing agent. However, a different behaviour was shown by the coated fabric when applied all the finishing agents simultaneously. Taguchi design enabled the monitoring of interdependency of different concentrations of chemicals and finding the most influencing parameters for efficient performance of coated fabrics.

Development of UV Protective, Superhydrophobic and Antibacterial Textiles Using ZnO and TiO2 Nanoparticles

In this research work, multifunctional cotton fabric comprising of UV protection, superhydrophobicity and antibacterial activity has been developed using facile pad-dry-cure method. In the first step, the concentration of repellent chemical has been optimized. Then, formulations containing nanoparticles of ZnO or TiO2 along with optimized concentration of repellent chemical and organic-inorganic binder have been applied to cotton fabric followed by the evaluation of functional properties. The surface morphology and elemental composition of treated fabric has been characterized through SEM and EDX, respectively. The treated samples have shown promising UV protection, superhydrophobicity and antibacterial properties durable upto 20 washing cycles.

Preparation of stable dispersion of ZnO nanorods and its application on cotton fabric for functional properties

In this systematic study, we describe the influence of various surfactants and polymers on aggregation stability of ZnO nanorods. Triton X-100, PVP and PVA were used to disperse nanorods. The surfactant/polymer stabilizing effect was monitored using the sedimentation study and photographic methods based on the decrease in the height of the interface as a function of time. The dispersion of nanorods when applied to cotton fabric, it exhibited functional properties like antibacterial activity and UV protection. The morphologies of nanorods and functionalized cotton were characterized by using SEM.