Romana Khan

Removal of reactive blue 19 dye by sono, photo and sonophotocatalytic oxidation using visible light.

An efficient sonophotocatalytic degradation of reactive blue 19 (RB 19) dye was successfully carried out using sulfur-doped TiO2 (S-TiO2) nanoparticles. The effect of various treatment processes that is sonolysis, photolysis, catalysis, sonocatalysis, photocatalysis, and sonophotocatalysis were investigated for RB 19 removal. S-TiO2 were synthesized in 1, 3 and 5 wt.% of sulfur by sol-gel process and characterized by X-ray diffraction (XRD) and scanning electron microscopy coupled with energy dispersive X-ray (SEM-EDX), UV-Visible diffuse reflectance spectra (DRS). The results confirm anatase phase of TiO2, porous agglomerate structure, and a red shift in the absorbance spectra of S-TiO2. The dye degradation was studied by using UV-Vis spectrophotometer at λ max=594 nm. The reaction parameters such as pH, catalyst dosage, initial dye concentration, ultrasonic power and effect of sulfur doping in different weight percent were studied to find out the optimum degradation conditions. Optimum conditions were found as: S-TiO2=5 wt.%, catalyst (S-TiO2 5 wt.%)=50mg, RB 19 solution concentration=20 mg L(-1), pH=3, ultrasound power=100 and operating temperature=25°C. The response of 5 wt.% S-TiO2 was found better than 1 and 3 wt.% S-TiO2 and other forms TiO2. The sonophotocatalysis process was superior to other methods. During this process the ultrasound cavitation and photocatalysis water splitting takes place which leads to the generation of OH. As reveled by the GCMS results the reactive blue 19 (20 mg L(-1)) was degraded to 90% within 120 min. The S-TiO2 sonophotocatalysis system was studied for the first time for dye degradation and was found practicable, efficient and cost effective for the degradation of complex and resistant dyes such as RB19.

Bacterial cellulose-zinc oxide nanocomposites as a novel dressing system for burn wounds

Bacterial cellulose possesses physical and mechanical properties of an ideal wound dressing material but lack of antimicrobial activity limits its biomedical applications. Therefore, in current study, the inherent wound healing characteristics of bacterial cellulose and antimicrobial properties of zinc oxide nanoparticles were combined. The reinforcement (impregnation) of zinc oxide nanoparticles into bacterial cellulose sheets was confirmed through various characterization techniques. The antimicrobial capacity of bacterial cellulose-zinc oxide nanocomposites was tested against common burn pathogens. The in-vivo wound healing and tissue regeneration of the nanocomposites was investigated in burn BALBc mice model. Characterization techniques confirmed the successful impregnation of nanoparticles into bacterial cellulose. Bacterial cellulose-zinc oxide nanocomposites exhibited 90%, 87.4%, 94.3% and 90.9% activity against Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Citrobacter freundii, respectively. Bacterial cellulose-zinc oxide nanocomposites treated animals showed significant (66%) healing activity. The histological analysis revealed fine tissue regeneration in composites treated group. These findings suggest that bacterial cellulose-zinc oxide nanocomposites could be a novel dressing material for burns.

Bacterial cellulose–TiO2 nanocomposites promote healing and tissue regeneration in burn mice model

The development of novel cutaneous wound treatments particularly for burns is of paramount importance due to complex pathophysiology, prevalent infection and clinical complexities associated with burn care. The main focus of the current study was to investigate the in vivo burn wound healing potential of bacterial cellulose (BC) and titanium dioxide (TiO2) nanocomposites (BC–TiO2). The physicochemical characterization of BC–TiO2 was carried out using FE-SEM, XRD and FT-IR. The antimicrobial activity of the nanocomposite was tested against Escherichia coli and Staphylococcus aureus through agar disc diffusion protocol. The in vivo wound healing efficacy was evaluated in burn wound model through wound area measurement, percent contraction and histopathology. The characterization results confirmed the successful incorporation of TiO2 nanoparticles into BC. The nanocomposites exhibited 81 ± 0.4% and 83 ± 0% inhibition against E. coli and S. aureus, respectively. The composite bandage showed good healing pattern with 71 ± 2.41% wound contraction. Histopathological evidence like the formation of healthy granulation tissue and the re-epithelization indicated the healing progression in the composite treated group. In comparison, the BC treated group has partial epithelization and signs of inflammation. These results proved that the composite dressing possesses an excellent healing potential with faster re-epithelization rate and accelerated wound contraction ability and thus could be a candidate for the development of cutaneous wound care products to address the limitations of the conventional wound dressing for burns.

An overview of the reaction conditions for an efficient photoconversion of CO2

Abstract Carbon dioxide (CO2) emission is one of the well-known causes of global warming. Photoconversion of CO2 to useful chemical compounds using solar energy is an attractive approach as it reduces the major greenhouse gas and promises a sustainable energy source. This method involves radical-chain reactions that form cation and anion radicals generated as a result of the reaction with photogenerated electrons (e−) and holes (h+) between metal oxide photocatalyst and the reactants. Therefore, the product distribution of a modified photocatalyst even under specific reaction conditions is difficult to predict. The CO2 photocatalytic reduction process is controlled by several conditions such as reactor configuration, photocatalyst type, and nature of the reducing agents. Here, we review the parameters such as temperature, pH, CO2 pressure, type of reductant, role of co-catalysts, dopants, and type of photocatalysts that influence the end products of the photocatalytic reduction of CO2. In this review, the different modifications recommended for the photocatalysts to improve CO2 reduction and receive maximum valuable end product (methane, ethanol, methanol, hydrogen, and carbon monoxide) have been listed. The discussion also includes specific behaviors of photocatalysts which lead to different product distribution. It has been noted that different metal and nonmetal dopants improve the activity of a photocatalyst and influence the end product distribution by altering the active species. Similarly, the key factors, i.e. size, morphology and doping, which have been ruling the photocatalytic activity of CO2 reduction under UV or visible light irradiation have been identified.

Spectrophotometric determination of methylamine moiety containing pesticides using ninhydrine reagent

A spectrophotometric method has been proposed for the determination of pesticides containing methylamine moiety. These pesticides afforded methylamine upon alkaline hydrolysis, which was subsequently reacted with ninhydrin in the presence of pyridine. The absorbance of the resulting blue-purple product was measured spectrophotometrically at 570 nm. The Beer’s law showed a linear relationship between absorbance and concentration of the pesticide in the range 0.04–5.0 μg/mL. The limit of detection and limit of quantification were 0.012 and 0.02 μg/mL, respectively. The repeatability was 0.22 expressed as RSD. The performance of this newly developed method was compared with the established spectrophotometric methods for the determination of these pesticides. The method has been successfully applied to the evaluation of these pesticides in commercial pesticide formulation and to the determination of monocrotophos in fruit samples.