Sorption of heavy metal ions by glass beads-immobilized calix[4]arenes derivative

Glass beads (GB) immobilized, 5,11,17,23-tetra-tert-butyl-25,27-diethoxycarbonylmethoxy-26,28-dihydroxycalix[4]arene (CA) are prepared and used as a new sorbent in sorption study of removal heavy metal ions. A calixarene derivative bonded to amino-functionalized glass beads sorbent was synthesized via a self assembly technique for sorbent of selected heavy metal ions in aqueous. In order to absorb selected heavy metal ions in aqueous, a calixarene derivative bonded to amino-functionalized glass beads sorbent was synthesized via a self assembly technique. The sorbent which is named GB-APTS-CA was characterized using infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), elemental analysis and thermal analysis (TGA/DTG). The influences of some experimental parameters including pH of the sample solution, weight of sorbent, concentration and temperature have been investigated. The sorption data were evaluated using the Langmuir, Freundlich and Dubinin Radushkevich (D-R) isotherm. The obtained maximum sorption capacity for Cu(II), and Pb(II) is 0.06 mmol g^?1 and 0.02 mmol g^?1, respectively. Thermodynamic parameters such as the standard free energy change (ΔG○), enthalpy change (ΔH○) and entropy change (ΔS○) were calculated to determine the nature of sorption process. Thus, GB-APTS-CA is favorable and useful for the removal of Cu(II) and Pb(II) metal ions.     

Assembly line balancing with positional constraints,task assignment restrictions and station paralleling: A case in an electronics company

In this paper, we present a real-life Assembly Line Balancing Problem for an electronics manufacturing company. The main characteristics of the problem are as follows: (i) a set of operations are related to the front part of the workpiece and others are related to the back part of the workpiece, which in turn makes all tasks dependent on the position of the workpiece, (ii) some of the tasks must be executed on the same station and no other tasks should be assigned to this station due to technological restrictions, (iii) parallel stations are allowed to increase the line efficiency at the required production rate and to overcome the problem of assigning tasks with operation times that exceed the cycle time. Initially, the problem is formulated as a 0–1 integer programming model and solved using CPLEX solver. Then, the effect of alternative work schedules such as multiple shifts and overtime on the expected labor cost of the line is analyzed. Considering alternative work schedules while balancing the line for corresponding cycle times allows us to select an efficient assembly line for the company, resulting in a lower labor cost and a more balanced line with respect to the operation times and the activity of the workers at each station. Lastly, a computational study is conducted to evaluate the performance of the proposed model. It is found that the model is capable of producing high quality solutions in reasonable solution times.     

AR–ARCH Type Artificial Neural Network for Forecasting

Neural Processing Letters - Real-world time series such as econometric time series are rarely linear and they have characteristics of volatility. Although autoregressive conditional...     

Nested simulated annealing approach to periodic routing problem of a retail distribution system

This paper introduces a real-life variant of a periodic traveling salesman problem (V_PTSP) for a retail distribution system. A warehouse is allocated to serve specified retail districts where a large number of retailers are located and the deliveries are planned according to the visiting frequency of each retailer. The objective is to determine daily vehicle routes over a given planning period adhering to the visiting frequency restrictions while minimizing the total distance traveled. Initially, the V_PTSP is formulated as an integer programming model. Since this model can only solve small size problems, a nested simulated annealing procedure is developed for solving large size V_PTSPs. A series of computational tests are performed for evaluating the performance of the heuristic procedure. The results show that the proposed approach gives good solutions in reasonably short computation times.     

Continuous fixed bed biosorption of reactive dyes by dried Rhizopus arrhizus: determination of column capacity

A continuous fixed bed study was carried out by using dried Rhizopus arrhizus as a biosorbent for the removal of three reactive dyes; Gemacion (Procion) Red H-E7B (GR), a monoclorotriazine mono-azo type reactive dye; Gemazol Turquise Blue-G (GTB), a vinyl sulfone mono-azo type reactive dye and Gemactive (Reactive) Black HFGR (GB), a vinyl sulfone di-azo type reactive dye from aqueous solution. The effect of operating parameters such as flow rate and inlet dye concentration on the sorption characteristics of R. arrhizus was investigated at pH 2.0 and at 25 degrees C for each dye. Data confirmed that the total amount of sorbed dye decreased with increasing flow rate and increased with increasing inlet dye concentration for each dye. The column biosorption capacity of dried R. arrhizus was 1007.8 mg g(-1) for GR dye, 823.8 mg g(-1) for GTB dye and 635.7 mg g(-1) for GB dye at the highest inlet dye concentration of approximately 750 mg l(-1) and at the minimum flow rate of 0.8 ml min(-1). Thomas and Yoon-Nelson models were applied to experimental data to predict the breakthrough curves and to determine the biosorption capacity of the column for each dye useful for process design. Both models were found suitable for describing the whole dynamic behavior of the column with respect to flow rate and inlet dye concentration.     

Carbon foam production from bio-based polyols of liquefied spruce tree sawdust: Effects of biomass/solvent mass ratio and pyrolytic oil addition

One of the next-generation structural materials is carbon foam. Porous materials have become an intriguing alternative material to traditional ones in many utilizations based on their light weight and incomparable properties. Coal or fossil oils are conventionally used to produce pitch, phenolic resin, and polyurethane as carbon foam precursor. Biomass liquefaction is a developing technique to convert biomass resources into the industrial chemicals. In this study, spruce tree sawdust was liquefied under mild conditions with different solvent type (phenol or phenol + bio-oil mixture). The unique aspect of this work is the synthesis of bio-polyol when pyrolytic oil is used as an alternative to phenol in the solvolysis reaction and its evaluation in carbon foam production with multilayer graphene sheets. Therewithal, the ratios of biomass to solvent were 1/3 as well as 1/5, and the comparison of product characteristics is another originality of the study. Slow pyrolysis of spruce tree sawdust was performed under static atmosphere and bio-oil was characterized with elemental analysis and various chromatographic and spectroscopic techniques. The effect of mass ratio of biomass/solvent on the characteristics of porous resin foams synthesized from liquefaction product. Obtained resin foams were carbonized at 400 °C, and then activated at 800 °C under nitrogen atmosphere. Structure evaluation of resin foams, carbonized foams, and activated carbon foams from liquefied spruce tree sawdust was investigated by using elemental analysis, x-ray diffraction, nitrogen adsorption/desorption isotherms, scanning electron microscopy, true/bulk density, and compressive strength tests. Although the surface area values decreased when bio-oil was added as a solvent, it was determined that the compression strengths of the produced carbon foams (up to 1.080 MPa) were higher than that of conventional phenolic foams. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47185.     

Construction of symmetric supercapacitors using anhydrous electrolytes containing heterocyclic oligomeric structures

The anhydrous electrolytes have become an important part of supercapacitors, which provide temperature-tolerant applications in various electronic devices. This work reports on the fabrication of a wide-temperature-range supercapacitor using 3-amino-1H-1,2,4-triazole (Atri)/1,4-butanediol diglycidyl ether (BG) and imidazole (Imi)/BG–based electrolytes in active carbon-based electrodes. The triazole-terminated BG (BG(Atri)₂) and Imi-terminated BG (BG(Imi)₂) were initially synthesized, and then anhydrous electrolytes were produced by doping BG(Atri)₂ and BG(Imi)₂ with phosphoric acid (H₃PO₄) and ionic liquid (IL) at different molar fractions. The supercapacitors constructed with the anhydrous BG(Atri)₂/H₃PO₄/0.1IL and BG(Imi)₂/H₃PO₄/0.1IL electrolytes provided maximum specific capacitances (Cs) of 114 and 191 F g⁻¹ at 1 A g⁻¹, respectively. The corresponding electrolytes yielded the highest energy densities of 15.8 and 26.7 Wh kg⁻¹ at the power densities of 1150 and 1225 W kg⁻¹, respectively. The Imi-terminated electrolyte-based supercapacitor indicated superior performance and efficiency even after 2300 charge-discharge cycles by holding 20% of its original capacitance. The temperature dependence of the supercapacitors' capacitances was studied, and they increased from 191 to 266 F g⁻¹ for BG(Imi)₂/H₃PO₄/0.1IL and from 114 to 148 F g⁻¹ for BG(Tri)₂/H₃PO₄/0.1IL as the temperature increased from 25°C to 75°C.