Efficient photocatalytic degradation of textile dye pollutants using thermally exfoliated graphitic carbon nitride (TE-g-C3N4).

Graphitic carbon nitride (g-C3N4), an organic photocatalyst was reported to have beneficial properties to be used in wastewater treatment applications. However, g-C3N4, in its bulk form was found to have poor photocatalytic degradation efficiency due to its inherent limitations such as poor specific surface area and fast electron-hole pair recombination rate. In this study, we have tuned the physiochemical properties of bulk g-C3N4 by direct thermal exfoliation (TE-g-C3N4) and examined their photocatalytic degradation efficiency against abundant textile dyes such as methylene blue (MB), methyl orange (MO), and rhodamine B (RhB). The degradation efficiencies for MB, MO, and RhB dyes are 92 ± 0.18%, 93 ± 0.31%, and 95 ± 0.4% respectively in 60 min of UV light irradiation. The degradation efficiency increased with an increase in the exfoliation temperature. The prepared catalysts were characterized using FTIR, XRD, FE-SEM, EDAX, BET, and UV-DRS. In BET analysis, TE-g-C3N4 samples showed improved surface area (48.20 m2/g) when compared to the bulk g-C3N4 (5.03 m2/g). Further, the TE-g-C3N4 had 2.98 times higher adsorption efficiency than the bulk ones. The free radicals scavenging studies revealed that the superoxide radicals played an important role in the photodegradation for dyes, when compared to the hydroxyl radical (.OH) and the photo-induced holes (h+), Photoluminescence (PL) emission and electrochemical impedance spectroscopy (EIS) spectra of TE-g-C3N4 indicated a lowered electron-hole pairs' recombination rate and an increased photo-induced charge transfer respectively. Further, the TE-g-C3N4 were found to have excellent stability for up to 5 cycles with only a minor decrease in the activity from 92% to 86.2%. These findings proved that TE-g-C3N4 was an excellent photocatalyst for the removal and degradation of textile dyes from wastewater.

Mechanical, biocompatibility and antibacterial studies of gelatin/polyvinyl alcohol/silkfibre polymeric scaffold for bone tissue engineering.

The current study focuses on the incorporation of natural polymers (gelatin, silk fibre) and synthetic (polyvinyl alcohol) polymer towards the fabrication of a novel composite for bone tissue engineering. The Electrospinning method was used to fabricate the novel gelatin/polyvinyl alcohol/silk fibre scaffold. XRD, FTIR and SEM-EDAX analysis was performed to characterize the composite. The characterized composite was investigated for its physical properties (porosity and mechanical studies) and biological studies (antimicrobial activity, hemocompatibility, bioactivity). The fabricated composite showed high porosity and the highest tensile strength of 34 MPa, with elongation at a break of 35.82 for the composite. The antimicrobial activity of the composite was studied and the zone of inhibition was measured around 51 ± 0.54 for E. coli, 48 ± 0.48 for S. aureus and 50 ± 0.26 for C. albicans. The hemolytic % was noted around 1.36 for the composite and the bioactivity assay revealed the formation of apatite on composite surfaces.

Bismuth and Vanadium-Substituted Yttrium Phosphates for Cool Coating Applications.

Luminescent yttrium phosphate is engineered into an environmentally benign near infrared (NIR) reflective yellow pigment by the substitution of bismuth and vanadium metals in the host lattice. A series of YP(1-x)V x O4 (x = 0, 0.05, 0.1, 0.15, 0.2, and 0.4), Y(1-y)Bi y PO4 (y = 0.1 and 0.3), and Y(1-y)Bi y P(1-x)V x O4 (x = y = 0.2, 0.4, and 0.6) were prepared by the precipitation method. Secondary phase was noticed at x = 0.2 and y = 0.2 while substituting vanadium and bismuth, respectively, due to high ionic radii of the dopant ions. Co substitution of vanadium and bismuth in the YPO4 lattice enhanced both NIR reflectance and yellow color of all the fabricated materials. XPS spectra proved the presence of trivalent bismuth and pentavalent vanadium in Y0.4Bi0.6P0.4V0.6O4. Due to the substitution effect, a more defined morphology was noticed, which enhanced the scattering co-efficient of the fabricated materials; hence, the NIR reflectance of the materials was increased from 68% (YPO4) to 83% (Y0.4Bi0.6P0.4V0.6O4). Chemical and thermal stability test of Y0.4Bi0.6P0.4V0.6O4 confirmed the color and strength of the designed pigment. With good yellow hue (b* = +56.06), high NIR solar reflectance (R* = 83%), and good stability, Y0.4Bi0.6P0.4V0.6O4 can act as an environmentally benign cool yellow pigment.

Tricomponent composite containing copper-hydroxyapatite/chitosan/polyvinyl pyrrolidone for bone tissue engineering.

The tricomponent composite chitosan/polyvinyl pyrrolidone (CS/PVP) with different weight ratios of (0, 20, 40, 60, and 80 wt%) of copper-hydroxyapatite (Cu-HAP) were prepared by solvent casting technique, which was characterized by X-ray diffraction, Fourier-transform infrared, and scanning electron microscopy with energy-dispersive X-ray to confirm the formation of Cu-HAP/CS/PVP composite. The Cu-HAP/CS/PVP composite with 80 wt% Cu-HAP showed 98.73 ± 1.14% of porosity with highest tensile strength (101.45 ± 0.98 MPa) and less swelling percentage (19.51 ± 1.03%) compared to others. In vitro antimicrobial activity was investigated against bacteria (Staphylococcus aureus, Bacillus subtilis, and Escherichia coli) and fungus (Candida albicans, Penicillium notatum, and Rhizopus stolonifer). In vitro hemocompatibility study proves that the Cu-HAP/CS/PVP composites are blood compatible with the hemolytic ratio of less than 2%. In vitro bioactivity study revealed the formation of apatite on the optimized Cu-HAP/CS/PVP composite (80 wt% of Cu-HAP) in simulated body fluid (SBF) solution. ICP-OES (Inductively Coupled Plasma-Optical Emission Spectroscopy) analysis was used to find out the leaching of Ca, P, and Cu ions from the SBF. In vitro biocompatibility was studied against human osteosarcoma cell line by MTT (3-(4,5-Dimethylthiazol-2-yl)-2,5-DiphenyltetrazoliumBromide) assay.

Zinc and manganese substituted hydroxyapatite/CMC/PVP electrospun composite for bone repair applications.

Zn-Mn HAP (Zinc and Manganese substituted Hydroxyapatite), CMC (Carboxymethyl cellulose)/PVP (Polyvinyl pyrrolidone) and (Zn-Mn HAP)/CMC/PVP (Zn = Mn = 0.05, 0.1 M) were prepared by hydrothermal and electrospinning methods respectively. The prepared composites were characterized using powder X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR) and Scanning Electron Microscopy (SEM) with Energy Dispersive X-Ray Analysis (EDAX) to examine the phase formation, functional groups and surface morphology. FTIR spectra of the composite confirmed the funcitonal groups present in the composite. SEM images showed the fiber formation and the incorporation of Zn-Mn HAP into the fiber structures. The physical properties like porosity, swelling and tensile strength was studied for the prepared composites. 0.1 M of (Zn-Mn HAP)/CMC/PVP (20, 40, 60 wt% of Zn-Mn HAP composite) showed good physical properties, in which the 60 wt% showed 98% of porosity with least swelling and the tensile strength was measured to be 67 MPa. Highest zone of inhibition was observed against the microbial organisms using this 60 wt% of 0.1 M of (Zn-Mn HAP)/CMC/PVP composite and it was also found to be hemocompatible with hemolysis value less than 3% when compared to other composites. The biocompatibility of the composite was evaluated using human osteoblast cells (HOS).

Copper and cerium co-doped cobalt ferrite nanoparticles: structural, morphological, optical, magnetic, and photocatalytic properties.

A rapid synthetic technique is investigated for magnetic nanoparticles (Co1-yCuyFe2-xCexO4 (x = 0, y = 0), (x = 0.05, y = 0), (x = 0, y = 0.5), and (x = 0.05, y = 0.5)). The structure, morphology, optical and magnetic performance of prepared nanoparticles are analyzed by powder XRD, XPS, FT-IR, SEM-EDAX, TEM, DRS, and VSM. The photocatalytic activity of the synthesized nanoparticles for the removal of the Congo red (CR) dye and bisphenol A (BPA) from aqueous solution is examined by UV-visible spectrometer. Research indicates that the co-doping of Cu2+ and Ce3+ showed marked effect on the structural, optical, magnetic, and photocatalytic properties of the CoFe2O4 nanoparticles. DRS showed that the Co0.5Cu0.5Fe1.95Ce0.05O4 nanoparticles have lower band gap energy (0.78 eV) than other synthesized compounds. High removal percentage of CR and BPA (99.09% and 99.33%) was observed within 30 min and 180 min under visible and UV-light illumination respectively using Co0.5Cu0.5Fe1.95Ce0.05O4. The corresponding photocatalytic degradation kinetics and mechanism are analyzed.

Synthesis of substituted 2H-chromenes by a three-component reaction as potential antioxidants.

A series of alkoxy-substituted 2H-chromenes were synthesized by a one-pot three-component reaction using salicylaldehydes, acetyl acetone and alcohol as reactant and medium with tetra-n-butylammonium fluoride (TBAF) as catalyst. Simple reaction conditions, short reaction time and overall good yield of products make this synthetic strategy an efficient one to synthesize 2H-chromene molecules. All the synthesized compounds were evaluated for antioxidant activities. Among all the new compounds, 5j and 5k showed good inhibition [Formula: see text] and [Formula: see text]) at 100 [Formula: see text] concentrations.