Formulation of Synthesized Zinc Oxide Nanopowder into Hybrid Beads for Dye Separation

The sol-gel prepared zinc oxide nanopowder was immobilized onto alginate-polyvinyl alcohol polymer blend to fabricate novel biocomposite beads. Various physicochemical characterization techniques have been utilized to identify the crystalline, morphological, and chemical structures of both the fabricated zinc oxide hybrid beads and their corresponding zinc oxide nanopowder. The thermal stability investigations demonstrate that ZnO nanopowder stability dramatically decreased with its immobilization into the polymeric alginate and PVA matrix. The formulated beads had very strong mechanical strength and they are difficult to be broken up to 1500 rpm. Moreover, these hybrid beads are chemically stable at the acidic media (pH < 7) especially within the pH range of 2–7. Finally, the applicability of the formulated ZnO hybrid beads for C.I. basic blue 41 (BB41) decolorization from aqueous solution was examined

Ammonia Decomposition over Alkali Metal (Li, K, Cs)-Promoted Bulk Mo₂N Catalyst

Ammonia (NH3), which has a 17.7 wt% gravimetric hydrogen density, has been considered as a potential hydrogen storage material. This study looked at the thermocatalytic decomposition of NH3 using a bulk Mo2N catalyst that was boosted by alkali metals (AM: 5 wt% Li, K, Cs). The K-Mo2N catalyst outperformed all other catalysts in this experiment in terms of catalytic performance. At 6000 h−1 GHSV, 100% conversion of NH3 was accomplished using the K-Mo2N, Cs-Mo2N, and Mo2N catalysts. However, when compared to other catalysts, K-Mo2N had the highest activity, or 80% NH3 conversion, at a lower temperature, or 550 °C. The catalytic activity exhibited the following trend for the rate of hydrogen production per unit surface area: K-Mo2N > Cs-Mo2N > Li-Mo2N > Mo2N. Up to 20 h of testing the K-Mo2N catalyst at 600 °C revealed no considerable deactivation

Extraction of Picric Acid from Wastewater by a Secondary Amine (Amberlite LA2) in Octan-1-ol: Equilibrium, Kinetics, Thermodynamics, and Molecular Dynamics Simulation

The paper deals with the equilibrium and kinetic studies on the reactive extraction of picric acid (HPc: 0.021–0.061 kmol·m^–3) using Amberlite LA2 (ALA2; 0.235–1.175 kmol·m^–3), a secondary amine, dissolved in an active diluent, octan-1-ol. On the basis of the values of the loading factor (<i>Z</i> < 0.5), the interaction between the molecules of HPc and ALA2 takes place by forming 1:1 solvates in the organic solvent phase and was confirmed from Fourier transfoem infrared analysis. The effect of the temperature (298.2, 308.2, and 318.2 K) on the performance of extraction is evaluated, and the thermodynamic parameters (entropy and enthalpy) are determined. The mass-transfer coefficient (<i>k</i>_L = 7.12 × 10^–4 m·s^–1) of picric acid in octan-1-ol is estimated experimentally to establish the kinetics of the reaction. The Hatta number is found to be in the range of 0.009–0.011, suggesting a very slow extraction reaction occurring in the bulk of the solvent phase. The reaction order is 1.2 with respect to HPc and 0.7 order with respect to ALA2 with rate constants of forward and backward reactions of 18.3 × 10^–6 and 4.94 × 10^–6 (kmol·m^–3)^−1.9·s^–1, respectively. The molecular dynamics behavior of the HPc + ALA2 + octan-1-ol system in the organic solvent phase is predicted from the simulated results

Extractive Separation of Pentanedioic Acid by Amberlite LA-2 in Various Solvents

Reactive extraction of pentanedioic acid using Amberlite LA-2 in different diluents, such as hexane, methylbenzene, kerosene, 4-methyl-2-pentanone, 2,6-dimethyl-4-heptanone, n-hexanone, 3-methyl-1-butanol, n-octanol, nnonanol, and n-decanol, respectively, was studied. At lower amine concentrations, K-D values of less than 1 were obtained but it improves as amine concentration was raised. Increase in amine concentration was found to increase the KD by 80-85% in inert diluents (hexane, methylbenzene and kerosene). In the chosen ketones, the extraction percentage follows the following trend 4-methyl-2-pentanone > DIBK > n-hexanone. Among the various diluents used, higher KD was obtained when alcohols were used as diluents. Mass action equilibria, linear solvation energy relationship modeling, and differential evolution (DE) was applied for estimating the model parameter and compare the model values with the experimental results of extraction equilibria.WOS:00037998860003

Investigation of Ternary Phase Diagrams of (Water plus Butyric Acid plus Phenyl Acetate) at Different Temperatures

The system {(water (1) + butyric acid (2) + phenyl acetate (3)} at different temperatures, such as 298.15 K, 308.15 K, 318.15 K, and at a constant pressure (101.3 +/- 0.5 kPa) in terms of liquid liquid phase equilibria were investigated. The solubility curves for each system were found. The consistency for the experiments to determine tie-lines was done by Othmer-Tobias method. NRTL and UNIQUAC equation correlated experimental data with good results. the consistency of UNIQUAC and NRTL for concerning ternary experimental data. The finest results were reached with UNIQUAC model (RMSD value is 0.087 for 298.15 K). Extraction ability of the solvents used in this study were assessed in term of distribution coefficients (D) (highest 5.20) and separation factors (s(f)) (highest 322)

Optimal Synthesis of Property-Based Water Networks Considering Growing Demand Projections

This paper presents a mathematical programming model for the optimal synthesis and retrofitting of water networks based on the properties of the streams that impact the processing in the plant and the environment. One important feature of the proposed approach is that it accounts for changes in the operation through a time horizon with growing demands. The optimization formulation considers changes in the demands and accounts for time-based variations in the flow rates required for the process sinks and constraints for properties in the process sinks and in the environment. Furthermore, the proposed model allows the installation of different units and the retrofitting of the water network over the considered time horizon. The objective function minimizes the total cost associated with the entire life of the project while accounting for the time value of money and the specific demands for the process and the environment that change through the life of the project. Two case studies are solved to show the applicability of the proposed approach

Economic and Technical Analysis of a Hybrid Dry Cooling Cycle to Replace Conventional Wet Cooling Towers for High Process Cooling Loads

Scarcity has made fresh water too economically and socially too valuable to be used by the processing industry without restriction. Wet evaporative cooling cycles offer competitive advantages in terms of CoP compared to other cooling cycles with relatively low cost but requiring extensive quantities of water. Dry cooling, on the other hand, requires large heat-transfer areas, in addition to high power requirements. In this study, a hybrid cycle is proposed for high-end cooling loads of 215 MW. The proposed cycle combines the benefits of phase change to make dry cycles competitive. Furthermore, the proposed cycle also diminishes the extensive use of various chemicals used in wet cooling cycles. The applicable dry bulb temperature range is 25–50 °C. Variations in cooling fluid cold temperature due to ambient conditions are curtailed to a maximum of 2 °C by the proposed cycle. A technoeconomic comparison of the proposed solution to wet evaporative cooling is presented, and the effects are summarized without providing extensive design calculations. ASPEN modules are used design and simulation

Optimal Synthesis of Refinery Property-Based Water Networks with Electrocoagulation Treatment Systems

This paper presents an optimization approach to the incorporation of electrocoagulation in the design of integrated water networks for oil refineries. A disjunctive programming formulation is developed to minimize the cost of the water-management system while including the characteristics of process water streams, recycle, reuse, and treatment of wastewater streams, performance of candidate technologies, and composition and property constraints for the process units and the environmental discharges. The performance of electrocoagulation was related to temperature pH and the concentration of phenols and sodium chloride. Ancillary units including pH adjustment, reverse osmosis, and heat exchangers were used to support the electrocoagulation unit. Two case studies are presented to show the applicability of the proposed model and the feasibility of using electrocoagulation as part of an integrated water management scheme for oil refineries