http://blogs.najah.edu/author/amer-elhamouz An-Najah Blogs :: Amer El-Hamouz en-us Thu, 18 Apr 2024 23:09:40 IDT Thu, 18 Apr 2024 23:09:40 IDT [email protected] [email protected] http://blogs.najah.edu/staff/amer-elhamouz/article/Dispersion-of-silicone-oil-in-water-surfactant-solution-Effect-of-impeller-speed-oil-viscosity-and-addition-point-on-drop-size-distributionPublished ArticlesThe preparation of dilute aqueous silicone oil emulsions has been investigated with particular attention to the effect of oil viscosity 049350 mPa s impeller selection equal diameter Sawtooth and pitched blade turbines and the method of addition of the oil Emulsification was found to be sensitive to how the oil was added to the vessel with narrower drop size distributions and smaller Sauter mean diameters d32 obtained when the oil was injected into the impeller region The equilibrium values were also attained in a shorter time with the equilibrium d32 We06 For addition of the oil to the surface the relationship was weaker with equilibrium d32 We04 The viscosity group was particularly useful in describing the behaviour of equilibrium particle sizes for different viscosity oils and also for viscosity changes arising from different process temperatures An unexpected result is that the Sawtooth impellor proved to be more energetically efficient at drop break-up producing smaller droplets than the Pitched Bade Turbine This result is particularly interesting since the power number for the latter is larger and therefore for equivalent operating conditions should produce smaller drop sizes We suggest that one possible reason is that the local shear rates for the Sawtooth impellor are larger Another possible reason is that the Sawtooth geometry provides more points where the local shear rates are high Chemical Engineering and Processing: Process Intensification Volume 48 Issue 2 February 2009 Pages 633-642 http:dxdoiorg101016jcep200807008http://blogs.najah.edu/staff/amer-elhamouz/article/Effect-of-cooling-rate-of-pre-annealed-CdS-thin-film-electrodes-prepared-by-chemical-bath-deposition-Enhancement-of-photoelectrochemical-characteristicsPublished ArticlesThin films of CdS deposited by chemical bath deposition CBD onto films of fluorine-doped tin oxideglass glassFTO substrates were prepared and investigated for photoelectrochemical conversion PEC of light into electricity Knowing the hazardous nature of CdS the focal theme of this work was to modify the electrodes by simple economic ways to maximize their conversion efficiency and minimize their degradation under PEC conditions This was to avoid leaching out of hazardous Cd2 ions Different parameters have been investigated for this purpose Multi-deposition preparation redox couple and electrode etching affected electrode PEC characteristics Consistent with earlier literature annealing the electrode enhanced its conversion efficiency and stability On the other hand effect of cooling rate of pre-annealed CdS electrodes prepared by CBD on their PEC characteristics has been investigated here for the first time Controlling the cooling rate was one major factor that affected CdS surface morphology conversion efficiency and stability under PEC conditions The major recommendation coming out here is that PEC characteristics of CdS thin film electrodes can be significantly enhanced by pre-annealing the electrode at 250C followed by its slow cooling http://blogs.najah.edu/staff/amer-elhamouz/article/Solid-olive-waste-in-environmental-cleanup-Oil-recovery-and-carbon-production-for-water-purification-2Published ArticlesA potentially-economic three-fold strategy to use solid olive wastes in water purification is presented Firstly oil remaining in solid waste higher than 5 of waste was recovered by the Soxhlet extraction technique which can be useful for the soap industry Secondly the remaining solid was processed to yield relatively high-surface area active carbon AC Thirdly the resulting carbon was employed to reversibly adsorb chromate ions from water aiming to establish a water purification process with reusable AC The technique used here enabled oil recovery together with the production of a clean solid suitable for making AC This process also has the advantage of low production costhttp://blogs.najah.edu/staff/amer-elhamouz/article/Chemical-Reaction-Engineering-Analysis-of-the-Blowout-Process-for-Bromine-Manufacture-from-Seawater-2Published ArticlesA chemical reaction engineering model has been constructed to describe the extraction and recovery of bromine from a once-through seawater flow The process uses a closed-loop circulation flow of air This strips out free bromine from pre-chlorinated seawater in a packed column Bromine liberated into the gas reacts with injected sulfur dioxide around a circulation loop to form liquid droplets containing product hydrobromic acid captured by mist elimination Excesses of chlorine and sulfur dioxide compete for bromine and can reduce the recovery efficiency Pseudo-homogeneous gas-phase kinetics accounts for simultaneous absorption and gasliquid reaction of liberated bromine excess chlorine and injected sulfur dioxide Re-circulating sulfur dioxide subsequently absorbs and reacts simultaneously with bromine and chlorine stripping Parameter values are deduced for typical bromine recovery of 70 The model can be used for optimizing the excesses of chlorine and sulfur dioxidehttp://blogs.najah.edu/staff/amer-elhamouz/article/Dye-effect-in-TiO2-catalyzed-contaminant-photo-degradation-Sensitization-vs-charge-transfer-formalism-Published ArticlesAnatase TiO2 surfaces have been treated with 246-triphenylpyrilium hydrogen sulfate TPPHS dye to yield the modified TiO2TPPHS surface The modified TiO2TPPHS surface was then supported onto activated carbon AC surfaces to yield a new class of catalytic system ACTiO2TPPHS The catalytic activities of naked TiO2 TPPHS solution TiO2TPPHS and ACTiO2TPPHS systems were examined in photo-degradation of phenol and benzoic acid in water using both UV and visible regions All studied systems showed low catalytic activity when used in the visible region In UV the ACTiO2TPPHS showed highest activity whereas the naked TiO2 and TPPHS solutions were the least active systems The dye role in enhancing activity of modified surfaces in UV degradation of contaminants is understandable by a charge-transfer catalytic effect rather than a sensitizing effect AC role is explainable by its ability to adsorb contaminant molecules and bringing them closer to catalytic sites Solid State Sciences Volume 9 Issue 1 January 2007 Pages 9-15 http:dxdoiorg101016jsolidstatesciences200610001http://blogs.najah.edu/staff/amer-elhamouz/article/Effect-of-Surfactant-Concentration-and-Operating-Temperature-on-the-Drop-Size-Distribution-of-Silicon-Oil-Water-Dispersion-1Published ArticlesThe effect of sodium lauryl sulphate SLES surfactant and the operating temperature on thedrop size distribution of a 350 cSt Dow Corning 200 series oil water dispersion was successfully studied The dispersion was prepared in a standard 6 litres mixing tank at different impeller speeds A measurement of the SLES critical micelle concentration CMC at 258C was carried out The interfacial tension of silicon oil water under various SLES concentration at a temperature range of 25 to 808C was accomplished Results showed that the interfacial tension of the silicon oil water decreased as the operating temperature increased and as the surfactant concentration increased When the operating temperature was increased at the highest SLES concentration tested a decrease of d32 was observed This was attributed to the possibility of hydration of the surfactant at high temperature Same behavior was observed when measuring the drop size distribution at constant temperature but different SLES concentration It was found that the mean drop size decreases with mixing time Different slopes of the change of the median drop size with time were obtained for different SLES concentration For the same concentration the slope changes after 1 hour The degree change of the slope is due to the change of interfacial area of the oil water as mixing time elapsed and the depletion of the surfactant concentrationhttp://blogs.najah.edu/staff/amer-elhamouz/article/Medical-waste-incineration-in-Nablus-City-West-Bank-A-case-studyPublished ArticlesMedical waste generated in West Bank hospitals and medical centers is collected in plastic bags and then dumped together with other domestic waste without any separation This malpractice usually leads to air pollution and the danger of spreading viruses and bacteria widely It is only in the last three years that medical waste has been separated from municipal waste in Nablus city and disposed of in a medical waste incinerator In this paper the type and quantity of the medical waste generated from four hospitals and two medical centers in Nablus City was recorded on daily basis for one month It was found that PVC plastic waste represents the largest amount of waste A computer reaction program was written to simulate the combustion process taking place during medical waste incineration and to calculate the emission factor and the amount of pollutant emission gases from the medical waste incinerator It has been found that the highest amount of pollutant emission gases was from burning plastic and glass medical waste In addition chlorinated hydrocarbons emissions such as dioxins and furans from the incineration process were also calculated using an existing model from the literature It has been found that the dioxinsfurans emissions increase with increasing HCl concentration and decreasing combustion temperature This confirms the need to control these pollutants from the medical waste incineratorhttp://blogs.najah.edu/staff/amer-elhamouz/article/MEDICAL-WASTE-INCINERATION-IN-NABLUS-CITY-WEST-BANK-A-CASE-STUDYPublished ArticlesMedical waste generated in West Bank hospitals and medical centers is collected inplastic bags and then dumped together with other domestic waste without any separationThis malpractice usually leads to air pollution and the danger of spreading viruses andbacteria widely It is only in the last three years that medical waste has been separated frommunicipal waste in Nablus city and disposed of in a medical waste incinerator In this paper the type and quantity of the medical waste generated from four hospitalsand two medical centers in Nablus City was recorded on daily basis for one month Itwas found that PVC plastic waste represents the largest amount of waste A computerreaction program was written to simulate the combustion process taking place duringmedical waste incineration and to calculate the emission factor and the amount ofpollutant emission gases from the medical waste incinerator It has been found that thehighest amount of pollutant emission gases was from burning plastic and glass medicalwaste In addition chlorinated hydrocarbons emissions such as dioxins and furansfrom the incineration process were also calculated using an existing model from theliterature It has been found that the dioxinsfurans emissions increase with increasingHCl concentration and decreasing combustion temperature This con rms the need tocontrol these pollutants from the medical waste incineratorhttp://blogs.najah.edu/staff/amer-elhamouz/article/HYDRODYNAMICS-AND-MASS-TRANSFER-OF-TEXTILE-VIBRATING-VALVE-TRAYSPublished ArticlesNew types of vibrating-va lve trays with textile valves were investigated to determine their optimal construction Hydrodynamic and mass transfer measurements were carried out in a pilot plant with different vibrating-valve and conventional valve trays under identical experimental conditions The total tray pressure drop Dp column efŽ ciency g volumetric mass transfer coefŽ cient KGa and pressure drop per theoretical tray DpNth were measured and comparedThe high mass transfer rate the low investment and operating costs the corrosion and heatresistance make the vibrating-va lve trays attractive for gas absorption and air cleaning inenvironmental protectionhttp://blogs.najah.edu/staff/amer-elhamouz/article/Effect-of-Shear-Produced-by-Pipe-Fittings-on-the-Drop-Size-Distributions-in-Turbulent-Flow-of-KeroseneWater-MixturesPublished ArticlesDrop size distribution data for kerosene-water dispersion were obtained in 1ID pipe at a range of velocities in turbulent flow for a straight horizontal pipe U shaped pipe and an offset pipe fitting oriented horizontally and vertically upward and downward to the main flow A Lightnin in line static mixer was used as a premixer and the drop size distribution was measured by a Malvern 2600 analyzer By changing the number of internal elements from 4 to 18 the mixer produced a primary dispersion with the mean drop sizes in the range of 50-700 um for the flow rates of 20 to Uminute The Sauter mean diameter d32 was found to decrease as the number of elements was increased until an equilibrium drop size was reached This equilibrium drop size varied with the fluid velocity through the mixer For a dispersion of ~05 kerosene in water the correlation of drop site with energy dissipation rate e was found to give a reasonable agreement with Kolmogoroffs theory mm ith au exponent in the range of -047 to -056 for a horizontal pipe and -060 to -072 for U-shaped and offset pipe fittings The Sauter mean diameter was also correlated against Weber number with an exponent in the range of -071 to -083 for all the linings usedhttp://blogs.najah.edu/staff/amer-elhamouz/article/Effect-of-micro-mixing-on-the-yield-of-intermediates-in-triplet-consecutivecompetitive-reactionsPublished ArticlesMicro-mixing calculations based upon a simplified non-deforming one-dimensional diffusion-reaction formulation are presented for the sequence of three reactions denoted by A B -- R B -- S B -- T This tripler reaction under micro-mixing is posed as five simultaneous parabolic partial differential equations which have been solved using a general purpose NAG library algorithm The primary product R has an improved yield under perfect mixing conditions The ultimate product T is shown to be always favoured by the perfect segregation of micro-mixing By contrast the central intermediate S gives high yields under micro-mixing at low conversions but perfect mixing is preferable at higher conversions in addition predictions show that yield improvements for S might be possible by an engineered stretching of fluid lamellae and by the combination of micro-mixing followed by perfect mixing especially at intermediate levels of conversion The calculations are relevant to multi-step halogenations and they help to explain how the anomolous appearance of a tri-halogenated species ahead of mono- and di-halogenated ones in a stirred vessel can be attributed to micro-mixinghttp://blogs.najah.edu/staff/amer-elhamouz/article/Effect-of-chemical-additives-on-the-stability-of-kerosene-water-dispersionsPublished ArticlesInterfacial tension data was obtained for kerosene and water in the presence of a demulsifier DE5010 and a corrosion inhibitor CP1260 used in offshore production Mixtures of these additives exhibited synergistic effects resulting in a decrease in interfacial tension greater than that observed in the presence of single additives The effect of the additives on the stability of kerosene in water emulsions was also determined It was found that when present alone the demulsifier significantly destabilized the mixture but in the presence of the corrosion inhibitor its effectiveness was markedly decreased Drop size distribution data was obtained on-line for the same systems in a pilot plant flow loop This data was compared with the relative stahility of the dispersion determined from laboratory measurementshttp://blogs.najah.edu/staff/amer-elhamouz/article/On-line-drop-size-distribution-measurement-of-oil-water-dispersion-using-a-Par-tec-M300-laser-backscatter-instrumentPublished ArticlesThe scanning laser microscope Par-tec has been used to measure drop size distributions of oil-water mixtures in both batch and on-line operations and the performance of the instrument has been assessed Measurements have been made to determine the influence of the shear produced by pipes and fittings on the dispersion characteristics of oil-water mixtures The influence of oil composition has also been investigated The Par-tec has been found to give reproducible mean chord data for oil-in-water and water-in-oil dispersions in both a batch mixing process and on-line at various dispersed phase concentrations and for both clear and optically dense oil systems However there were some important limitations noted Firstly the drop size measured by the instrument is not a drop diameter as measured by most other particle sizing instruments but a drop chord length; secondly the drop size was found to vary with the focal length of the instrument Changes in drop size due to changes in process conditions can easily detected using the Par-tec instrument In this work the effect of horizontal pipe length and number of bends was investigated It was found that the drop size increased with increasing horizontal pipe length due to drop coalescence The drop size was also found to increase as the number of bends in the pipe was increased in a 15 ID U-pipe fitting indicating that the energy dissipated in the system is not enough to outweigh the effect of coalescence due to the pipe length The sequence of pipe fitting was found to influence the nature of dispersion The value of the mean chord at the exit of a needle valve followed by a small U-pipe fitting was not the same as the mean chord for the U-pipe followed by the needle valve The main advantages of this instrument are its flexibility it can be easily inserted into process streams in most pipes and vessels and its ability to obtain data in two phase systems with high dispersed phase concentrations andor an optically dense continuous phasehttp://blogs.najah.edu/staff/amer-elhamouz/article/Computational-fluid-mixing-for-stirred-vessels-progress-from-seeing-to-believingPublished ArticlesQuantitative visualization of chemical processes and the consequent incorporation of images into process control loops was an idea that ET Woodburn et al pioneered in mineral processing This approach is based on the notion that many chemical processes possess intrinsic visual indicators which are otherwise difficult to instrument Stirred vessels used as chemical reactors have the same potential to benefit from quantitative imaging although in this case not just for control purposes but also as a powerful adjunct to model development and validation We outline developments pursued at UMIST which seek to utilize image reconstruction modelling of mixing to interpret simple tracer diagnostic tests and thereby to predict chemical reactor behaviour under semi-batch operation Progress from small two-dimensional axisymmetric networks-of-zones through larger three-dimensional networks-of-zones to computational fluid dynamics predictions in full three dimensions are outlined Problems requiring more advanced techniques and models to link macro-scale mixing to micro-mixing form a wide set of challenges for future researchhttp://blogs.najah.edu/staff/amer-elhamouz/article/Reactors-Kinetics-and-Catalysis-A-product-distribution-paradox-on-scaling-up-a-stirred-batch-reactorPublished ArticlesFor a triplet competitive-consecutive halogenation sequence forming mono- di- and trihalogenated products of the form A B R B S B T under semibatch operation adding B to A if perfect mixing could be assumed at all scales the product distribution would be unchanged on scaling up However if the reaction rates are reasonably faster than the mixing rate the semibatch addition of B to A will be imperfectly backmixed exhibiting macroscale concentration gradients This partial segregation of the primary reagents is capable of modifying the selectivity and corresponding appearance of R S and T in the course of the batch Imperfect mixing is quantified using the networks-of-zones model The effect of scaling up at equal tip speed is examined for a lab-scale 03-dm3 reactor a semitech 30-dm3 reactor and a production-scale 3000-dm3 vessel The intensity of partial segregation is weak at the lab scale but very severe at the production scale The lab-scale reactor is therefore close to perfectly backmixed and the primary secondary and tertiary products appear in sequence At the semitech scale the increased partial segregation causes the final product to initially precede the secondary product paradoxically but lag the initial product At the large scale the more severe segregation between A and B gives an even greater paradox whereby the final product appears ahead of both the primary and secondary ones The segregated concentration fields of A and B are visualized as sectional image reconstructions for networks comprising on the order of 1000 zones Localized intensive plumes of B emanating from the addition point cause the paradoxical reversals of product sequences The calculations are directly relevant to real industrial miscible liquid halogenations for which product distribution paradoxes have been observed Haywood 1990