A chitosan polymer was magnetized by coating with magnetite Fe2O3 nanoparticles, and the resultant material (C-Fe2O3) was first characterized through scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy, transmission electron microscopy, atomic force microscopy, thermogravimetric, X-ray diffractometry, Fourier transform infrared spectroscopy, Brunauer-Emmett-Teller, and point of zero charge analyses. C-Fe2O3 was then employed as a separable and efficient adsorptive agent to remove acid blue 113 (AB113) dye from aqueous solution. The removal efficiency was optimized at different environmental parameter values (pH: 3-11, C-Fe2O3 dose: 0.1-1 g/L, initial AB113 dye concentration: 10-100 mg/L, adsorption time: 0-300 min, and temperature: 388-318 K). Under optimum conditions, an AB113 dye removal efficiency of 99.68% was achieved. In addition, the effect of the presence of NaCl, NaNO3, Na2CO3, and MgSO4 ions on the AB113 dye removal efficiency could be ranked as NaCl> NaNO3> MgSO4> Na2CO3. The statistical analysis using the coefficient of determination, root mean square error, chi-square test, sum of squared errors, and average relative error showed that the Freundlich and pseudo-second-order equations were the best mathematical models for fitting the isothermal and kinetics data. Further kinetics analyses showed that the adsorption of AB113 molecules on C-Fe2O3 active sites was dominated by the intraparticle diffusion process. Thermodynamic parameters indicated that the AB113 dye adsorption process was favorable, endothermic, and spontaneous. Furthermore, an increase in temperature had a positive impact on AB113 dye removal. The regeneration study confirmed the excellent shelf life of C-Fe2O3, with only a slight loss in the removal efficiency (<7%) being detected after six operational cycles of AB113 dye adsorption. Compared with other adsorbents, 3 C-Fe2O3 was more effective for the adsorption of AB113 dye, with an adsorption uptake up to 128 mg/g.
This paper is focused on studying the factors affecting the productivity of excavation works in Jordan. In order to investigate this target, a questionnaire was designed considering the most important factors that were proposed in the literature, then distributed to 55 of experts and contractors. Accordingly, the collected data was analyzed using SPSS software in order to evaluate those factors and to arrange them based on their importance sequence.In general, several major factors affect the productivity of excavation works in construction projects. In this research, five of those factors were selected and studied, evaluated, and concluded to be the most major factors that could influence the productivity of excavation works for construction projects in Jordan, and could significantly affect the cost and time of carrying out the project. Accordingly, the results of this research showed that the increase in the productivity for excavation works is related to taking into account the factors recommended according to their priority, in which the first of these was the "the types and readiness of the excavation machines", followed by (in descending order) "the geological nature of the site", "the project site investigation", "the technical expertise specialized in carrying out excavation works", and "the financial liquidity and the payment of dues".
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