Herein, graphene (GN) was synthesized, exfoliated by anchoring dodecyl sulfate chain through hydrophobic interaction over its surface (GN-SDS), and was tested to sequester Cu(II) and Mn(II) ions in single-metal system from aqueous phase. Acid-base titrations and elemental analysis results verified successful dodecyl sulfate chain anchoring over GN-SDS surface. Adsorption/desorption isotherms depicted Type-IV isotherm with H3 type hysteretic loop, confirming mesoporous nature of GN-SDS with BET surface area – 242 m2/g. The ID/IG ratios of GN and GN-SDS obtained by RAMAN spectroscopy were 0.8537 and 0.8540, respectively confirming no distortion in structure during modification. Electrostatic interaction between metal ions and negative surface charge and-/or Cπ electrons of GN-SDS was governing the adsorption process. Maximum Cu(II) and Mn(II) adsorption on GN-SDS was observed at pH 5 and 6, respectively. Rapid Cu(II) and Mn(II) adsorption kinetics accomplishing 80–92% and 87–96%, respectively at varied concentration in 60 min was observed. Maximum adsorption capacities for Cu(II) and Mn(II) on GN-SDS were 369.16 and 223.67 mg/g, respectively. Langmuir isotherm and pseudo-second-order kinetic models were fitted to experimental data. Thermodynamically favorable adsorption process was observed. 30–33% drop in GN-SDS adsorption potential for Cu(II) and Mn(II) after five consecutive regeneration cycles was observed.

Although the third wave of democratization overturned autocracies around the world, Libyan and Egyptian regimes stayed afloat for a long period. Libya and Egypt were ruled by dictatorial regimes for decades, but there were varying degrees of tyranny in both countries. One means of comparing political transition in Libya and Egypt is to examine both regimes’ structures. Qaddafi’s regime was a personalistic regime that lacked the genuine institutions that could rein in Qaddafi's singularity by power and by ruling the country. In contrast Mubarak regime was seen as a hybrid regime in that it apparently combined democratic and authoritarian institutions, but in reality, it was a dictatorship regime. Mubarak regime used democratic institutions as a facade to hide the real nature of the regime .The political system is dominated by the president, who has strong legislative powers and can dissolve parliament. Keywords: political transition, military institution, civil war

Medium carbon V-microalloyed steel continuously cooled from the austenitization temperature at still air, with predominantly acicular ferrite structure, has been investigated by means of four-point bending of notched Griffiths–Owens’s type specimens at liquid nitrogen temperature. Local fracture stress and plastic strain were determined by using finite element analysis and fracture surface examination using scanning electron microscope. It was revealed that cleavage fracture initiation, which takes place close to the notch root in the narrow zone of high plastic strains, is not related to any broken coarse second phase particles. It was assumed that microcracks nucleate by strain induced fracture of pearlite nodules. Two effective surface energy values of 24 and 42 J/m2 were estimated according to the Griffith’s equation, indicating the influence of crystallographic orientation between neighboring grains at the origin of fracture. Lower value was attributed to fracture of coarse ferrite–pearlite units with similar crystallographic orientation and higher value to fracture propagation through fine acicular ferrite matrix.

Abstract

The main purpose of catalytic reforming unit is to upgrade low-octane naphtha to high-octane gasoline. In this work, the estimation capacities of the response surface methodology (RSM) and artificial neural network (ANN), to determine the research octane number (RON) of reformates produced from the catalytic naphtha reforming unit were investigated. The article presents a comparative study and combined application between response surface methodology (RSM) and artificial neural networks (ANN) based on design of experiment (DOE) strategy in the modeling and prediction of the research octane number (RON). In this study, DOE⿿CCRD full factorial design was incorporated into the ANN methodology, so the need of a large quantity of training data was avoided. ANN methodology showed a very obvious advantage over RSM for both data fitting and estimation capabilities. Based on the results of analysis of variance (ANOVA), a multiple determination coefficient of 0.8 and 0.99 were obtained for both RSM and ANN respectively. It has been found that by employing RSM approach coupled with ANN model based on DOE strategy, the visualization of the experimental points in three dimensional spaces can disclose qualitatively and quantitatively the activity relationships. This approach of combination of RSM⿿ANN⿿DOE has revealed its ability to solve a quadratic polynomial model involving solving, optimization, complexity and difficult relationships especially nonlinear ones may be investigated without complicated equations involved. The study revealed that, the maximum RON of 88 was obtained at the optimum conditions offered by RSM. Furthermore, at the optimal conditions of (T = 521 °C, P = 37.6 bar, LHSV = 2.02 h⿿1), the maximum RON of 98 was obtained for the ANN model. However, the models were implemented for the construction of 3D response surface plots from the ANN and RSM models in order to show the most effective variables as well as the effects of their interaction on the research octane number.

Abstract. Economic development in line with improvement life style is the ultimate purpose in a modern society. Most low-income and developing Asian countries are facing a number of challenges with respect to sustainable waste managing from their industrial activities. On the other hand, these countries aim to be industrialized and consequently, generate huge industrial solid wastes with an increasing trend. Land fill disposal is the most practiced method for handling industrial solid wastes among Asian countries. It was pointed out that illegal industrial waste disposal has increased sharply due to the land scarcity. Meanwhile, there is less attention to practicing waste minimization as a sustainable and effective strategy for controlling industrial solid wastes in developing Asian countries. The lack of significant factor such as strict regulation and strong enforcement, awareness and knowledge, enough funding, technology and skilled manpower are found as the main hindrances to sustainable industrial waste management among Asian countries. This paper is a mini review paper that aimed to compare the current practicing of different waste management options by industries in Asian countries by highlighting challenges and approaches in sustainable solid waste management.

Keywords: asian countries, waste minimization, industrial wastes, landfill disposal, sustainable waste management, hindrances 

Abstract:

A new trend in catalytic naphtha reforming requires the decrease of aromatics hydrocarbons particularly benzene in reformate, while maintaining high octane rating. At present, production of reformulated gasoline with low content of benzene is one of the main challenges in the transportation fuel industry. In the catalytic reforming of realistic naphtha over bi-functional Pt-Re-S/Al2O3-Cl catalysts the: (i) liquid yield (C5 +), (ii) yield of aromatics, (iii) iso paraffin/aromatics ratio, (iv) side reactions (hydrocracking, hydrogenolysis, coking) as responses can be altered by controlling the independent reaction parameters (Temperature, Pressure, Liquid Hourly space velocity (LHSV), Hydrogen to hydrocarbon ratio (H2/HC ratio), chlorine and the addition of different promoters to the catalyst (Re, Sn, Ir, etc). In the present report, a quadratic polynomial equation for the responses Research Octane Number (RON), Neglect this statement as these models has been removed were obtained by multiple regression analysis and tested using analysis of variance (ANOVA) with 95% degree of confidence. The validation of experimental data was confirmed with the predicted model. The results showed that the reaction temperature and the total operating pressure are the key variables that have the main influence on naphtha reforming reactions by the synergistic effect of linear term (X1, X2), which is in a good agreement with the experimental data reported previously in the literature.

Keywords: Catalytic naphtha reforming, Pt-Re bifunctional catalyst, Research octane number, Response surface methodology (RSM), Central composite design, Optimization. 

To reveal the prior-austenite grain boundaries in micro-alloyed steels there is different techniques. This study has been carried out over a wide range of temperature (950-1150 οC) and it has been found that the tested procedure based on the combination of heat treatment and thermal etching (TE) method give excellent results for the Titanium and Titanium free medium carbon micro-alloyed steels at all the austenitization conditions tested.