Presence Of Large Surface Area Research Articles

Synergistic Adsorptive Removal of Urea from Agricultural Effluents Using Ball Clay and Sepiolite Composite

Agriculture effluents have become a big problem since water is the basic component of all operation in agriculture practice. These effluents composed of agrochemicals such as fertilizer, pesticides, herbicides, crop residues are the pollutants of agricultural effluents. Lakes, rivers and streams often receives water run-off from farmlands. Nitrates and urea in the water bodies are toxic to aquatic lives by causing depletion of oxygen in water making it unfit for human and aquatic life. This research assessed the adsorptive removal of urea from agricultural effluent by means of thermally activated ball clay and sepiolite composite (TABCSC) and non-activated ball clay and sepiolite composite (NABCSC) as absorbent. The adsorption process was done at Varying amounts TABCSC (0.6g - 4.5g), pH range of 3 - 11, time (30 - 90 minutes) and temperature (25 – 45°C) as recommended by design expert version 13. TABCSC and NABCSC characterized by means of Fourier transformed infrared spectroscopy (FTIR) and scanning electron microscope (SEM) reveals the presence of large surface area, porosity as well as the functional groups: hydroxyl, carboxylic, hydrogen bonding and aldehyde group that aids adsorptive removal of urea. The highest adsorptive removal efficiency by TABCSC was found to be 99.23% (at pH = 7, temperature = 25°C, dosage = 0.6 g and time = 60 minutes) while that of NABCSC was at 93.23% (at pH = 11, temperature = 35°C, dosage = 0.6 g and time = 60 minutes). The adsorptive removal of urea was found to increase with increase in pH value and contact time. The adsorptive removal mechanism of Urea by TABCSC was more fitting to the second order kinetics (R2 = 0.9770) while removal by NABCSC aligns with the pseudo first order kinetics (R2 = 0.9770). The isotherm of the removal process conforms more to the Freundlich isotherm of TABCSC (R2 = 0.9995) and NABCSC (R2 = 0.9671) respectively.

Enhanced ethanol vapor sensing by 2D CuO-ZnO composite at ambient conditions

Gas sensors find application in the fields of food packaging, medical, agriculture, industries, transport, storage, and warehousing, etc. An efficient gas sensor should be sensitive and selective towards analyte, have fast response and recovery time and operate under moderate conditions. The commercial sensors have an in-built heating element. Thus, there is scope for finding materials that can function as room temperature ethanol sensors. Here, a composite of two-dimensional copper oxide (CuO) with zinc oxide (ZnO) nanoparticles is reported as a potential ethanol (EtOH) vapor sensor under ambient conditions. CuO is synthesized with the help of liquid–liquid phase separation technique yielding architecturally aligned 2D structures. ZnO nanoparticles are synthesized via microwave assisted wet chemical route separately. X-ray diffraction studies show the phase formation of pure CuO and ZnO individually. The CuO and ZnO samples are ground mechanically in 1:1 wt ratio to form a composite referred to as CZC. The optical absorption studies show bandgap of CuO structures as 1.41 eV, ZnO as 3.13 eV, and of CZC as 1.24 eV. A slurry of the composite is then coated on a glass substrate to study the resistance changes after ethanol vapor exposure. It is observed that while pure CuO is almost unresponsive to EtOH vapors, ZnO has sluggish response, the CZC samples responded fast. The best average response time is observed to be ∼ 4 sec while recovery time is ∼ 12 sec. The sensors show good reversibility as they return to their initial state without applying any heat treatment. The change in EtOH sensing in composites is attributed to the formation of heterojunction between CuO-ZnO which facilitates faster electron transfer across the heterojunction and the presence of large surface area renders an increased number of adsorption sites.

Study and optimization of lens shape affecting light patterns of light-emitting diode (LED) street lighting

The aim of this study was to evaluate the effect of lens shape towards the light performance from light-emitting diode (LED) based street light. The other consideration taken into account was the effect of different light-emitting surface (LES) shapes on the light distribution. Three sets of experiments were carried out to figure out the shape of lens as well as the shape of LES suitable to be used in the street light application. Optical characterization was carried out using the Goniophotometer (GO-2000) and Integrating Sphere (PCE-200A). DIALux Evo software was used to perform simulation by taking the ME4A road lighting requirement set by Tenaga Nasional Berhad (TNB) as a benchmarking. In comparison, Lens D possessing short rounded rectangular lens demonstrated a better light performance as compared to long rounded rectangular and triangular lenses, owing to the acquisition of lesser light trespass problems. Besides, a better light performance was demonstrated by square-shaped LES as compared to the round-shaped LES due to the presence of large surface area that was able to distribute light evenly. Detailed investigation was presented.

Preparation of biosensor based on triarylmethane loaded cellulose acetate xerogel for the detection of urea

Urea released by kidney into blood and urine is a major reason for the gradual loss of kidney function. Therefore, it is of great importance to construct a real-time detection method for Urea. On the other side, a sponge-like microporous cellulose acetate (CA) xerogel has been introduced as a low-density biomaterial with various promising applications. In this study, a facile, portable, fast, and highly sensitive microporous CA biopolymer test dipstick, comprising triarylmethane (TAM) as a spectroscopic chromophore and urease (U) enzyme as a catalytic agent, is constructed for colorimetric detection of urea. Identification of urea occurs via proton transfer from the hydroxyl substituent of TAM to ammonia released in an aqueous environment from the hydrolysis of urea/urease reaction. Importantly, TAM probe was in-situ integrated within the generated sponge-like CA dipstick sensor assay (CA-U-TAM). This resulted in ratiometric changes of 131 nm red-shift in the absorption spectra, from 439 nm to 580 nm, as a function of the urea total content in the aqueous medium. Additionally, composition/morphology of the prepared CA-TAM dipstick was explored and revealed the presence of large surface area and high porous scaffolds with a pore size of ∼7.5 μm.

Effect of pure and REM: (Nd, Ce)-doped Dy2O3 NPs via hydrothermal method and their magnetic, optical, electrochemical, antibacterial and photocatalytic activities

Pure Dysprosium oxide (Dy2O3) with the spherical-morphology based material, and the rare earth metal (REM) - doped Dy2O3 nanoparticles (NPs) were synthesized using the reaction of dysprosium (III) nitrate pentahydrate, neodymium (III) nitrate hexahydrate and cerium (III) nitrate hexahydrate by the simple cost-effective hydrothermal method, which exhibits high antibacterial effects and photocatalytic activity. The antibacterial effect of pure and (5 mol% of Nd, Ce) - doped Dy2O3 NPs, on Bacillus subtilis, Staphylococcus aureus, Pseudomonas aeruginosa and Salmonella typhi were studied by using various concentrations. The photocatalytic activity of pure and 5 mol% of cerium doped Dy2O3 NPs were assessed by degrading the methyl orange (MO) dye under UV irradiation. The characterization results indicated that the XRD and TEM studies confirms the size of the prepared Dy2O3 NPs decreased with Nd and Ce insertion into dysprosium oxide. The particle size calculated from the Williamson-Hall (W-H) plot was consistent with TEM results. From VSM analysis, cerium doped NPs shows high saturation (Ms) magnetization than that of pure Dy2O3 NPs. The emission spectra and electrochemical properties are found to be dopant dependent. 5 mol% of Ce-doped Dy2O3 NPs shows good antibacterial effect compared to that of pure and Nd doped sample. From the above, it is observed that cerium doped NPs exhibit high photocatalytic activity than pure NPs. The mineralization of MO dye solution for pure and 5 mol% of Ce-doped samples has been confirmed by chemical oxygen demand (COD) measurements. In addition, the rate of decolorization is also confirmed by the total organic carbon (TOC) study. From the results, cerium doped sample enhances the photocatalytic performance compared to pure Dy2O3 NPs due to the lower recombination rate of electron-hole pairs and the presence of large surface area of the samples act as reactive facets for adsorption of MO dye molecules.

Unconventional magnetism in ZnO nanorods

ABSTRACTWe report room temperature ferromagnetism in vacuum annealed ZnO nanorods. ZnO nanorods were annealed at 600°C for 6 hours in an annealing chamber with a pressure of 10−6 Torr. Our study indicates that ZnO nanorods develop room temperature ferromagnetism due to the presence of oxygen vacancy defects in it. Presence of large surface area of nanorods and oxygen vacancy are mainly responsible for the observed magnetic behavior.

Morphological influence of TiO2 nanostructures (nanozigzag, nanohelics and nanorod) on photocatalytic degradation of organic dyes

Hierarchical nanostructures have drawn significant attention and incredible performance in photodriven chemical conversion area due to its unique physicochemical properties. Herein, we study the morphological influence of TiO2 nanostructures on photocatalytic degradation of different organic dyes methyl blue, methyl violet and methyl orange present in industrial wastewater. Nanorod, nanohelics and nanozigzag TiO2 nanofilms were fabricated by using galancing angle deposition technique (GLAD). TiO2 nanofilms were characterized by scanning electron microscope (SEM), X-ray powder diffraction (XRD), and raman analysis. BET surface area analysis were carried out by using nitrogen adsorption desorption curves. The results show that TiO2 morphology had great influence on photocatalytic degradation of organic dyes due to difference in specific surface area and pore volume of nanostructures. The photocatalytic degradation experiments were carried out for three hours under UV–vis light irradiation. Catalysis recycling and organic dyes concentration influence were also studied. In case of high concentration of organic dyes, negligible degradation rate is observed. TiO2 nanozigzag films show better degradation performance than nanohelics and nanorod due to presence of large surface area for reaction, higher porosity with dispersion of active sites at different length scales of pores and presence of oxygen vacancies.

Electrodeposition of three-dimensional Ni(OH)2 nanoflakes on partially crystallized activated carbon for high-performance supercapacitors

Three-dimensional Ni(OH)2 nanoflakes were prepared via a facile and cost-effective electrodeposition method using commercial activated carbon (AC) as substrate. Nitric acid treatment (NT) and partial crystallization (PC) by metal nickel catalysis were applied for AC. The effects of the oxygen-containing functional groups and the degree of crystallization on the electrochemical performance of the electrode were investigated. The resulting Ni(OH)2/PC–NT–AC/nickel foam electrode exhibits distinct performance with a specific capacitance of 2971 F/g (scaled to the mass of active Ni(OH)2) at a current density of 6 A/g. A high capacitance of 1919 F/g was still achieved even at 40 A/g, which is much higher than Ni(OH)2/AC/nickel foam electrode and Ni(OH)2/NT–AC/nickel foam electrode. The excellent performance of Ni(OH)2/PC–NT–AC/nickel foam electrode can be attributed to the presence of large surface area and highly conductive PC–NT–AC network on nickel foam. This study presents an effective method to improve the dispersion and rate capability of Ni(OH)2 nanostructure electrodes.