Nitrogen release properties of urea–kaolinite controlled release fertilizer with chitosan binder

To reduce environmental and economic concerns of feeding crops with traditional fertilizers, a new type of controlled release fertilizer was prepared. In this study, urea–kaolinite was mixed with chitosan as a binder and then was granulated. The granules were incubated in water at room temperature for 30 days and urea release was measured in 5-days intervals using UV/Vis technique and through diacetylmonoxime (DAM) calorimetric method. In this study, different binder concentration was investigated. The results of UV–Vis spectroscopy illustrated that by increasing the chitosan concentration, nitrogen release decreased from 41.23 to 25.25 % after 24 h and from 77.31 to 59.27 % after 30 days incubation in water. By doing this, the prepared controlled release fertilizer (CRF) behaved according to the standard for CRFs. Compressive stress at break was measured for granules with different size and various concentration of chitosan. Results show that the force required to crush the granules is a function of the granule diameter and binder concentration

Assessment of gas flow characteristics and reaction kinetics of chemical vapour deposition reactors for the production of nano-hybrid fibres

Chemical vapour deposition (CVD) had been used to produce carbon nanotube (CNT) coated carbon fibre, referred to in this work as nano-hybrid fibres. In order to understand the gas flow behaviour inside the CVD reactor, computational fluid dynamics (CFD) has been utilised to simulate the process in a horizontal CVD reactor together with a vertical CVD reactor for comparison. For simplicity purposes, the CNT synthesis was represented by ferrocene decomposition into iron, which acts as the catalyst for CNT formation. The gas flow behaviour inside the horizontal reactor was asymmetrical in nature and seen to be dominated by recirculation effects compared with the vertical reactor, which was symmetrical and generally lacking in circulation. The impact of the gas flow characteristics on the reaction rates of the ferrocene decomposition and mass fraction of chemical species was also investigated. The kinetic rate of reaction in the horizontal reactor was found to be 2–3 orders of magnitude larger in the horizontal reactor compared with the vertical reactor. The results provide valuable insight into the best approach for producing nano-hybrid fibres in a one-step continuous process

Green Fabrication of Copper Nanoparticles Dispersed in Walnut Oil Using Laser Ablation Technique

Synthesis of copper nanoparticles was achieved by laser irradiation of copper plate in walnut oil. The copper plate was irradiated using Nd:YAG pulse laser at different ablation time from 5 to 50 minutes, and the prepared samples were characterized using analytical methods to find the optical absorption, morphology, particle size, and capping of copper nanoparticles with walnut oil. Consequently, the absorption peak appeared at about 615, 606, 588, 576, and 561 nm; and the nanoparticles formed in spherical shape in walnut oil. The particle size varied from 25 to 4.01 nm, and the tail of the carbonyl band capped the copper nanoparticles through the electron transfer from the carboxylic group to copper nanoparticles. The refractive indices of the nanofluid were measured using a surface plasmon resonance technique and changed from 1.4691 + 0.008i to 1.4682 + 0.043i as the volume fraction increased from 0.0257 × 10 −5 to 1.26 × 10 −5 . Consequently, the laser ablation method is environmentally sensitive (i.e., green) and thus is suitable for the fabrication of copper nanoparticles in walnut oil without any agent

CVD whiskerization treatment process for the enhancement of carbon fiber composite flexural strength

Carbon fiber composite performance can be enhanced by applying an optimum level of fiber surface treatment such as whiskerization. The main objectives of this study were to conduct whiskerization through carbon nanotube (CNT)-coating of carbon fiber via chemical vapour deposition (CVD) at various conditions (temperature and hydrogen flow rate) and to investigate the enhancement in flexural strength of composites fabricated from these CNT-coated carbon fibers. The results indicated that CNTs were able to grow onto the carbon fibres with the highest amount of whiskerization occurring for samples nearest the reactant gas inlet of the CVD Rig. Various whiskerization behaviours were observed at different reaction temperatures and flow rates. From flexural tests, it was found that whiskerization treatment on carbon fibers increases the flexural strength of its composites between 44-122%

Shear thinning and frequency dependent behaviour of adsorbed polymer layers Part I. Experimental aspects and a first order analysis

Nanorheological measurements were carried out using an oscillatory AFM technique to investigate the viscoelastic properties of adsorbed hydroxypropyl guar (HPG) layers. The oscillations were performed at frequencies between 300 Hz and 1 kHz, with applied oscillation amplitudes of 2 nm. Qualitative data analysis was carried out using complex viscosity and complex modulus transfer functions based on a hydrodynamic lubrication model. The results indicated viscous behaviour at large surface separations and viscoelastic behaviour in the region of polymer layer overlap, as would be expected for adsorbed polymer layers. However, the adsorbed HPG layers also showed an indication of frequency dependent viscoelastic behaviour and shear thinning (reduction of viscosity with frequency). Furthermore, there appeared to be an unanticipated correlation between the apparent thickness of the adsorbed layers and the viscoelastic properties of the system, which may be attributed to the shear thinning behaviour of the layers

Dish concentrator performance based on various materials for hot humid weather

In this paper, three solar dish systems with different reflector materials were experimentally studied for five months. The size each of the solar dish is 32 cm in diameter and 5 cm in depth. The focal length of the dish concentrator was 12.8 cm. The solar dishes were made from aluminum, aluminum covered with chrome and ABS canister covered with 3M aluminum foil on its surface. Experimental measurement for total heat flux showed that 3M aluminum foil is higher than aluminum and chrome. The experimental results indicate that the total efficiency of the system is up to 49.7%

Investigating the effects of using different types of SiO2 nanoparticles on the mechanical properties of binary blended concrete.

The aim of this study was to assess the effects of two different types of SiO2 nanoparticles (N and M series) with different ratios on the workability and compressive strength of developed binary blended concretes cured in water and lime solution as two different curing media. N and M series SiO2 nanoparticles with an average size of 15 nm were used as obtained from the suppliers. Fresh and hardened concretes incorporating 0.5%, 1.0%, 1.5% and 2.0% of N and 2% of M series nanoparticles with constant water to binder ratio and aggregate content were made and tested. Fresh mixtures were tested for workability and hardened concretes were tested for compressive strength at 7, 28 and 90 days of curing. Fresh concrete test results showed that the workability of binary blends was reduced in the presence of both types of SiO2 nanoparticles. Hardened concrete test results revealed that the optimal replacement level of cement by N series of SiO2 nanoparticles for producing concrete with considerably improved strength was set at 1.0 wt.% after curing in water. However, the ultimate strengths of binary blended concretes were gained at 2.0 wt.% replacement of cement by both series after curing in lime solution. It is concluded that SiO2 nanoparticles play significant roles in mechanical properties of concrete by formation of additional calcium silicate hydrate gel during treatment, which played an important role in raising highly the compressive strength of binary blends. The current study sheds light on the implications of nanotechnology in nano-engineering of concrete

Multi-wall carbon nanotubes/styrene butadiene rubber (SBR) nanocomposite

A floating catalyst chemical vapor deposition (FC-CVD) method was designed and fabricated to produce high-quality and -quantity carbon nanotubes. The design parameters like the hydrogen flow rate; reaction time and reaction temperature were optimized to produce high yield and purity of Multi-Wall Carbon Nanotubes (MWCNTs). Multi-Walled Carbon Nanotubes (MWNTs) were used to prepare natural rubber (NR) nanocomposites. Our first efforts to achieve nanostructures in MWNTs/styrene butadiene rubber (SBR) nanocomposites were formed by incorporating carbon nanotubes in a polymer solution and subsequently evaporating the solvent. Using this technique, nanotubes can be dispersed homogeneously in the NR matrix in an attempt to increase the mechanical properties of these nanocomposites. The properties of the nanocomposites such as tensile strength, tensile modulus, elongation at break and hardness were studied. Using different percentages of carbon nanotubes from 1 wt% to 10 wt%, several nanocomposites samples were fabricated. Significant improvements in the mechanical properties of the resulting nanocomposites showed almost 10% increase in the Young’s modulus for 1 wt% of CNTs and up to around 200% increase for 10 wt% of CNTs

Laser Ablation Technique for Synthesis of Metal Nanoparticle in Liquid

Recently, the synthesis and application of metal and ceramic nanoparticle are significant subject in science and engineering. The metal nanoparticles such as silver, gold, and copper nanoparticles have more application in material science, nanomedicine, electronic, photonic, and art. One of the green methods for preparation of metal nanoparticles is laser ablation technique that offers a unique tool for nanofabrication of nanoparticles. In this technique, the high-power laser ablates the metal plate and the nanoparticles are formed in the liquid. The properties of nanoparticles using laser ablation are unique, and they are not reproducible by any other method such as chemical methods. The important parameters to produce the metal nanoparticles are energy, wavelength, repetition rate of laser, ablation time, and absorption of an aqueous solution. Laser ablation is a simple method for fabricating the metal nanoparticles without surfactant or chemical addition. In this chapter, the mechanism of formation of metal nanoparticles in liquid, significant parameters for using the laser ablation technique to prepare the metal nanoparticles, and the preparation of silver, gold and copper nanoparticles will be reviewed