TiO2-rGO Composite for Photocatalytic Decolorization of Methylene Blue Under the Visible Light Illumination

Titanium dioxide-reduced graphene oxide (TiO2-rGO) was synthesized by hydrothermal method using TiO2 powder and rGO precursor from graphite rod by modified Marcano Method. The obtained TiO2-rGO photocatalyst was characterized by X-Ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FT-IR), and Diffuse reflectance UV (DRUV). Based on XRD diffractogram, it is known that TiO2 has an anatase crystal phase. In the FTIR spectrum, it was observed that there was an absorption peak at the wavenumber of 1630 cm-1 from the vibration (C=C) as an indication that the C atom was incorporated into the TiO2 structure. The incorporation of C atoms into the TiO2 structure to form TiO2-rGO causes the bandgap energy to decrease from 3.29 eV to 3.20 eV. The photocatalytic activity was tested against decolorization of methylene blue solution for 180 minutes under visible light illumination from a 50 watt LED lamp. Every 10 minutes, absorbance was measured using a UV-Vis spectrophotometer at a wavelength of 664 nm. TiO2-rGO photocatalyst has better photocatalytic activity with %D of 96.39% under UV light and 84.32% under visible light illumination, while TiO2 is only able to degrade 93.87% and 36.55%, respectively.

Cyanophycean (Cyanobacterial) diversity from the Lakhimpur-Khiri District of Northern Uttar Pradesh, India

In the present study, the cyanophycean diversity of the Lakhimpur-Khiri district, northern Uttar Pradesh, India, has been investigated for the first time. Algae samples were collected in plastic bottles and preserved in 3-4% formalin from Lakhimpur-Khiri district of northern Uttar Pradesh in different seasons from 2015 to 2016. The field photographs of the selected localities were also taken and the location of each site noted down. For the Microscopic study of Cyanophycean algae, the samples were stained with 1 % aqueous methylene blue solution according to the standard method. The observations and photomicrography were done with help of Nikon Labophot-11 microscope. A total of 31 cyanophycean algal taxa have been recorded from different water bodies of Lakhimpur-Khiri. These algal taxa belong to 14 genera and 9 families of the division Cyanophyata. Of these, Oscillatoria (7), Phormidium (4) and Lyngbya (3) are abundant.

Colorimetric determination of trace orthophosphate in water by using C18-functionalized silica coated magnetite

In this study, we customized magnetic sorbents by functionalizing silica coated magnetite with octadecyl(C18)silane (Fe3O4@SiO2@C18). This sorbent was intended for the determination of trace orthophosphate (o-PO43−) in unpolluted freshwater samples. The o-PO43− was transformed to phosphomolybdenum blue (PMB), a known polyoxometalate ion. Then the PMB were coupled with cetyl trimethyl ammonium bromide (CTAB), cationic surfactant, in order to hydrophobically bound with the Fe3O4@SiO2@C18 particles through dispersive magnetic solid-phase extraction (d-MSPE) as part of sample preconcentration. The PMB–CTAB–magnetic particles are simply separated from the aqueous solution by the external magnet. The acidified ethanol 0.5 mL was used as PMB-CTAB eluent to produce an intense blue solution, which the absorbance was measured using a UV–Vis spectrophotometer at 800 nm. The proposed method (employing 2 mg of Fe3O4@SiO2@C18) yielded an enhancement factor of 32 with a linear range of 1.0–30.0 µg P L−1. Precision at 6.0 µg P L−1 and 25.0 µg P L−1 were 3.70 and 2.49% (RSD, n = 6) respectively. The lower detection limit of 0.3 µg P L−1 and quantification limit of 1.0 µg P L−1 allowed trace levels analysis of o-PO43− in samples. The reliability and accuracy of the proposed method were confirmed by using a certified reference material. Our method offers highly sensitive detection of o-PO43− with simple procedures that can be operated at room temperature and short analysis time.

Preparation of BiOCl/Bi2WO6 Photocatalyst for Efficient Fixation on Cotton Fabric: Applications in UV Shielding and Self-Cleaning Performances

In this work, a visible-light-driven BiOCl/Bi2WO6 photocatalyst was obtained via a facile hydrothermal method and characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS), X-ray photoelectron spectroscopy (XPS), ultraviolet/visible light diffuse reflection spectroscopy (UV/Vis), and photocurrent (PC). BiOCl/Bi2WO6 was modified with (3-chloro-2-hydroxypropyl) trimethyl ammonium chloride to obtain the cationized BiOCl/Bi2WO6. Cotton fabric was pretreated with sodium hydroxide (NaOH) and sodium chloroacetate solution to obtain carboxymethylated cotton fabric, which was further reacted with cationized BiOCl/Bi2WO6 to achieve finished cotton fabric. The cotton fabrics were characterized by Fourier-transform infrared spectroscopy (FT-IR), XRD, SEM, and EDS. The photocatalytic activity of the BiOCl/Bi2WO6 photocatalyst and cotton fabrics was assessed by photocatalytic degradation of MB (methylene blue) solution under simulated visible light. The self-cleaning property of cotton fabrics was evaluated by removing MB solution and red-wine stains. Results revealed that the coated cotton fabrics exhibited appreciable photocatalytic and self-cleaning performance. In addition, anti-UV studies showed that the finished cotton fabrics had remarkable UV blocking properties in the UVA and UVB regions. Therefore, the finished cotton fabric with BiOCl/Bi2WO6 can provide a framework for the development of multifunctional textiles.

Fabrication and Characterization of Cobalt-Pigmented Anodized Zinc for Photocatalytic Application

Population growth and urbanization have led to water scarcity and pollution, which is a health hazard not only to humans but also to the ecosystem in general. This has necessitated coming up with ways of treating water before consumption. Photocatalysis has proved to be one of the most promising cheap techniques that involve chemical utilization of solar energy. TiO2 widely used in photocatalysis absorbs a narrow range of the solar spectrum compared to ZnO. In this regard, this study aimed at preparing and optimizing cobalt-pigmented ZnO, which is applicable in photocatalytic water treatment. The objectives in this study were to fabricate zinc oxide (ZnO) thin films by anodization, pigment the fabricated films with varying cobalt concentrations, characterize the fabricated films optically, and investigate the cobalt-pigmented ZnO’s performance in the methylene blue degradation under UV light irradiation. Mirror-polished zinc plates were sonicated in ethanol and rinsed. Anodization was done at room temperature in 0.5 M oxalic acid at a constant voltage of 10 V for 60 min, and cobalt electrodeposited in the films. Post-deposition treatment was done at 250°C. Optical properties of the films were studied using a UV-VIS- NIR spectrophotometer in the solar range of 300–2500 nm. The photocatalytic activity of the fabricated films was studied in methylene blue solution degradation in the presence of UV light irradiation for 5 h. Cobalt pigmenting was observed to reduce reflectance and optical band gap from 3.34 to 3.10 eV indicating good photocatalytic properties. In this study, ZnO film pigmented with cobalt for 20 s was found to be the most photocatalytic with a rate constant of 0.0317 h−1 and hence had the optimum cobalt concentration for photocatalytic water treatment. This can be applied in small-scale water purification.

Synthesis of titania fibers by electrospinning and its photocatalytic degradation properties

The electrospinning precursor solution was prepared by dissolving polyvinyl pyrrolidone as template, tetrabutyl titanate as titanium source, and acetic acid as inhibitor. The TiO2 nanofilms were prepared by precursor solution electrospinning and subsequent calcination. Thermal gravimetric analysis (TG), scanning electron microscopy (SEM), X-ray powder diffraction (XRD), and transmission electron microscopy (TEM) were used to characterize and analyze the samples. The influence of technological parameters on spinning fiber morphology was also studied. The results indicate that the TiO2 nanofibers morphology is good when the parameters are as follows: voltage 1.4×104 V，spinning distance 0.2 m，translational velocity 2.5×10-3 m·s-1, flow rate 3×10-4 m·s-1, and needle diameter 3×10-4 m. The diameter of the fibers is about 150 nm. With the 1×10-4 mol·L-1 methylene blue solution used as simulated degradation target, the degradation rate is 95.8% after 180 minutes.

Equilibrium kinetic and isotherm studies of dye colour adsorption on the banana peel

Textile, paper, rubber, plastics, leather, cosmetics, pharmaceuticals, and food industries extensively employ dyes. This study aims to determine the best equilibrium kinetic and isotherm model of dye colour adsorption using waste adsorbent. Methylene blue (MB) is a dye colour contaminant that can be removed from wastewater via adsorption due to its ease of usage and cost-effectiveness. This study employed banana peels (BPs), a low-cost and waste adsorbent, to remove MB from synthetic wastewater. A series of batch equilibrium adsorption studies investigated the effect of different dosages of 0.05 to 0.4 grams, contact time of 15 to 150 minutes, and agitation speed of 150 rpm. BPs dosage is added from 0.05 g to 0.4 g in 100 ml of Methylene Blue solution. The concentration of MB in the samples was determined using a HACH DR2800 Spectrometer. According to the kinetic study analysis, the adsorption of MB followed a pseudo-second order kinetic with an R2 of 0.9934. Furthermore, the Freundlich model fit better than others based on the equilibrium isotherm investigation, with an R2 of 0.7688. As a result, BPs can be used as an alternative waste adsorbent media for extracting dye colours from industrial effluent.

Synthesis of Nano-ZnO/Diatomite Composite and Research on Photoelectric Application

The key to the commercialization of sustainable energy conversion technologies is the development of high-performance catalysts. The discovery of a stable, efficient, and low-cost multi-function catalyst is key. We used a simple green precipitation method to load diatomite nanozinc oxide particles onto a diatomite substrate. The ZnO is nano-sized. This precipitation method produces ZnO nanoparticles in situ on diatomite. The catalyst degraded 90% of a Methylene blue solution and also degraded gaseous benzene and acetone. Not only can the catalyst be used for the organic degradation of wastewater, but it also has the potential to degrade volatile organic compounds. Photocatalytic efficiency is closely related to the generation and separation of photosynthetic electrons and holes. The effective suppression of the composite rate of photoliving carriers, and thus improvement of the photocatalytic activity, has become a key research area. At present, At present, photocatalysis is an effective technology to inhibit photocarrier synthesis, which is often studied in sewage treatment. Photocatalytic water treatment reduces the combination of photoelectrons and holes by applying an external bias, thus improving the quantum efficiency for the complete mineralization of organic pollutants. The composite catalyst was used for oxygen and hydrogen extraction reactions, and a comparison of the catalysts with various loading ratios showed that the electrolysis water activity of the in situ loaded catalyst is due to pure ZnO, and the efficiency is highest when the loading ratio is 10%. This work provides new methods for the design and further optimization of the preparation of electrolytic aqueous catalysts.