H.A. Farag

Fe-Ni alloy/polyamide 6 nanocomposites: effect of nanocrystalline metal particles on the mechanical and physical properties of the polymer

The focus of this study is to explore the potential use of Fe40Ni60/Polyamide 6 (PA6) nanocomposites in engineering applications by providing understanding of how the nanocrystalline (nc) metallic particles are altering physical properties of the polymer and the corresponding reinforcing mechanisms. This is the first study using nc Fe-Ni alloy, which has unique various properties, as a filler for polymers. nc Fe40Ni60 particles were chemically synthesized. The composites with various nanofiller loadings were made by compounding the materials, either by melt mixing (MM) or via solution mixing (SM), and injection molding. The results show that SM composites have remarkable mechanical and thermomechanical properties, but MM ones exhibit deteriorated properties. In addition, morphological and crystalline structure analyses indicate that there is good interfacial interaction between nanofiller and polymer only in SM composites. This is because the ferromagnetism of Fe-Ni alloy could be only overcome by intensive compounding. It is concluded that there are four competing factors determining the overall performance of SM composites: i) degree of agglomeration and particle distribution within PA6 matrix and physical structural changes that occurred in PA6 due to presence of alloy particles including ii) crystallinity; iii) ratio of γ-form to α-form crystals; and iv) Glass transition temperature (Tg) of PA6. Overall, compared to other conventional nanoreinforcements for PA6, nc Fe-Ni alloy shows great promise and can lead to a new class of metal-polymer nanocomposites.

Feed salinity and cost-effectiveness of energy recovery in reverse osmosis desalination☆

For salinities covering the range from brackish water to highly saline sea water (50 fold range of salinities), effect of energy recovery (ER) on unit cost of desalination by reverse osmosis (RO) is sought. Since recovery is a primary factor in this respect, variables affecting recovery are considered in such a way that ensures trouble-free operation of RO units. Limiting conditions such as maximum and minimum allowable brine flow rates, maximum product flow, and limiting brine osmotic pressure are introduced as limiting factors in design calculations for one mgd (3785 m3/d) single stage plant. Results presented graphically show possible working ranges for different feed salinities. Maximum technically feasible recovery (YTF) defined for each salinity is determined and chosen for calculating cost-reduction expected from ER. A sensitivity analysis is also conducted to determine the effect of electrical energy unit cost. Results show that ER is expected to render cost reduction that warrants its use for seawater desalination at all normal levels of salinity. However, energy unit cost higher than 6 cents/kWh may be needed for noticeable cost reductions with brackish waters.

Recovery of nickel from spent catalyst by single- and multi-stage leaching process

Nickel-supported catalyst is used in petroleum, fertiliser and iron industries. This research studied the possibility of recovering nickel by leaching the ground catalyst with sulphuric acid. The leaching was done in single stage and multi-stages. The results obtained in single-stage leaching showed that the percentage recovery of nickel increased with increasing acid concentration used up to 25% and then the percentage recovery of nickel decreased. Also, the percentage recovery of nickel increased as the time of leaching increased. The optimum time was 3 h with three stages, each stage for 1 h. Using multi-stages gave 82% recovery while using two stages with the same acid concentration for 2 h gave 84% recovery. Increasing the number of stages leads to the use of lower acid concentration.

Recovery of some valuable components from industrial waste

ABSTRACT The present work studied several ways for wastewater treatment for the waste from the pulp and paper industries including the recovery of some valuable components from this waste and reaching the acceptable environmental limits for the treatment of waste. The acidification technique showed high efficiency for the removal of solids from the black liquor. A proper treatment for the effluent produced from the pulp and paper industry that used rice straw as raw material. The dose of the alum as a coagulant has an effect on the solid process and is due to the high percentage of solids in the black liquor. Hydrochloric acid is used to control the pH of the solution and separating most of the solids from the black liquor. Sodium hydroxide can be used to remove silica from the other solids by forming sodium silicate. The amount of solids precipitated increased by increasing the stirring time, temperature, rpm of the agitator, and decreasing pH. IR spectroscopy was carried out on the solid to assign the functional groups. Thermal analysis and EDX analysis were done to study the thermal properties of the solids. A proper design of the mixer and drier is accomplished to provide high efficiency of the silica removal process.

A novel one-step synthesis for carbon-based nanomaterials from polyethylene terephthalate (PET) bottles waste

ABSTRACT Nowadays our planet suffers from an accumulation of plastic products that have the potential to cause great harm to the environment in the form of air, water, and land pollution. Plastic water bottles have become a great problem in the environment because of the large numbers consumed throughout the world. Certain types of plastic bottles can be recycled but most of them are not. This paper describes an economical solvent-free process that converts polyethylene terephthalate (PET) bottles waste into carbon nanostructure materials via thermal dissociation in a closed system under autogenic pressure together with additives and/or catalyst, which can act as cluster nuclei for carbon nanostructure materials such as fullerenes and carbon nanotubes. This research succeeded in producing and controlling the microstructure of various forms of carbon nanoparticles from the PET waste by optimizing the preparation parameters in terms of time, additives, and amounts of catalyst. Implications: Plastic water bottles are becoming a growing segment of the municipal solid waste stream in the world; some are recycled but many are left in landfill sites. Recycling PET bottles waste can positively impact the environment in several ways: for instance, reduced waste, resource conservation, energy conservation, reduced greenhouse gas emissions, and decreasing the amount of pollution in air and water sources. The main novelty of the present work is based on the acquisition of high-value carbon-based nanomaterials from PET waste by a simple solvent-free chemical technique. Thus, the prepared materials are considered to be promising, cheap, eco-friendly materials that may find use in different applications.

Modeling of fluidized bed reactor for ethylene polymerization: effect of parameters on the single-pass ethylene conversion

BackgroundIn this study, we present the developments in modeling gas-phase catalyzed olefin polymerization fluidized bed reactors (FBR) using chromium catalyst technique. The model is based on the two-phase theory of gas-solid fluidization: bubble phase and emulsion phase. The model has proved to be the suitable model in many of past studies. In the proposed model, the bed is divided into several sequential sections. The effect of important reactor parameters such as superficial gas velocity, catalyst injection rate, catalyst particle growth, and minimum fluidization velocity on the dynamic behavior of the FBR has been discussed. The conversion of product in a fluidized bed reactor is investigated and compared with the actual data from the plant site.ResultsA good agreement has been observed between the model predictions and the actual plant data. It has been shown that about 0.28% difference between the calculated and actual conversions has been achieved.ConclusionsThe study showed that the computational model was capable of predicting the hydrodynamic behavior of gas-solid fluidized bed flows with reasonable accuracy.