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RISS 인기검색어
- 검색키워드
- 저자 : Khaled Hosni (검색결과 4 건)
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Khaled Mahmoudi,Khaled Hosni,Noureddine Hamdi,Ezzeddine Srasra 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.2
The adsorption of Methylene blue and Methyl orange by date pits carbon was carried out by varying parameterssuch as agitation time, pH and dye concentration. Equilibrium adsorption data followed both Langmuir and Freundlichisotherms. Adsorption followed second-order rate kinetics. The adsorption capacity was found to be 434 and455mg of methyl orange and methylene blue, respectively, per g of the date pits carbon. Acidic pH is favorable for theadsorption of methyl orange against a basic medium which is favorable for the adsorption of MB. An opposite resultwas found for the methylene blue adsorption.
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Synthesis, structure and photocatalytic activity of calcined Mg-Al-Ti-layered double hydroxides
Khaled Hosni,Omar Abdelkarim,Najoua Frini-Srasra,Ezzeddine Srasra 한국화학공학회 2015 Korean Journal of Chemical Engineering Vol.32 No.1
−Mg-Al-Ti layered double hydroxides (LDH), consisting of di-, tri- and tetra-valent cations with differentAl3+/Ti4+ratio, have been synthesized by co-precipitation which was demonstrated as efficient visible-light photocata-lysts. The structure and chemical composition of the compound were characterized by PXRD, FT-IR, SAA, N2 adsorp-tion-desorption isotherms, and DSC techniques. It is found that no hydrotalcites structure were formed for Ti4+/(Ti4++Al3+)>0.5 and the substitution of Ti(IV) for Al(III) in the layer increases the thermal stability of the resulting LDHmaterials. The calcined sample containing titanium showed relatively high adsorption capacity for MB as compared tothat without titanium. Results show that the pseudo-second-order kinetic model and the Langmuir were found to cor-relate the experimental data well. The photocatalytic activity was evaluated for the degradation of the methylene blue. The photocatalytic activity increased with the increase of the Al/Ti cationic ratio. 71% of the dye could be removed bythe Mg/Al/Ti-LDH with the cationic ratio Al/Ti=0 : 1 and calcined at 500 oC.
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A Model for Assessing Maximum Overtime Rate in Labor Subcontracting Practices
Nassar, Khaled,Hosny, Ossama Korea Institute of Construction Engineering and Ma 2012 Journal of construction engineering and project ma Vol.2 No.2
Despite the rapid development in the construction industry due to the changing new technologies, many projects still fail to meet target deadlines. Shortage in manpower and skilled laborers is one of the main reasons for such delays. Markets with high economic growth and economic expansion (such as Gulf Countries in the Middle East) may have pronounced labor the shortages. Labor subcontracting practices are used sometimes to increase production rates and meet project deadlines. This paper explains and analyses labor subcontracting practices currently being used in many places around the world (and especially in the Gulf Countries) and in particular defines a maximum overtime rate for laborers in the laborer-subcontracting method ensuring that the contractor gains both the time saved during overtime and also reduces the cost per unit produced. The mathematical model used formalizes a closed-form equation for overtime pay in similar situations and as such can be applicable worldwide. Data was collected from representative projects that employed such practices from various trades. Validation of the model and formula has been tested successfully by analyzing historic data. The results prove that contractors often do not reach the optimum use of their practices resulting in a higher cost per unit. The presented model and the analysis should be of interest to many contractors currently involved in the practice or considering its use and to those who wish to find new methods that would help in eliminating as much wastes as possible by allocating their resources in the most efficient way.
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FTIR study of gamma and electron irradiated high-density polyethylene for high dose measurements
Hanan Al-Ghamdi,Khaled Farah,Aljawharah Almuqrin,Faouzi Hosni 한국원자력학회 2022 Nuclear Engineering and Technology Vol.54 No.1
A reliable and well-characterized dosimetry system which is traceable to the international measurementsystem, is the key element to quality assurance in radiation processing with cobalt-60 gamma rays, Xrays,and electron beam. This is specifically the case for health-regulated processes, such as the radiationsterilization of single use medical devices and food irradiation for preservation and disinfestation. Polyethylene is considered to possess a lot of interesting dosimetric characteristics. In this work, adetailed study has been performed to determine the dosimetric characteristics of a commercialized highdensitypolyethylene (HDPE) film using Fourier transformed infrared spectrometry (FTIR). Correlationshave been established between the absorbed dose and radiation induced infrared absorption in polyethylenehaving a maximum at 965 cm 1 (transvinylene band) and 1716 cm 1 (ketone-carbonyl band). We have found that polyethylene dose-response is linear with dose for both bands up to1000 kGy. Fortransvinylene band, the dose-response is more sensitive if irradiations are made in helium. While, forketone-carbonyl band, the dose-response is more sensitive when irradiations are carried out in air. Thedose-rate effect has been found to be negligible when polyethylene samples are irradiated with electronbeam high dose rates. The irradiated polyethylene is relatively stable for several weeks after irradiation.
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