In this study, MCM-48 mesoporous silica was functionalized with dendrimer amines based on [1,3,5]-triazines (DA-S-Triazines), characterized by FT-IR, XRD, TEM and N2 sorption-desorption isotherm. The results confirmed the successful graft of organic functional groups on the MCM-48 surface. Then, it was used for the selective sorption of Ag (I) from aqueous solution and real wastewater in the batch system. The effect of main parameters on equilibrium sorption capacity and removal percentage including sorbent dose, pH, contact time, initial metal ion concentration and temperature was investigated. The results showed that the sorption of Ag (I) by DA-S-Triazines@MCM-48 was pH independent in the range of 3–8. The sorption capacity of MCM-48 strongly increases from 7.23 to 123 and 169.49 mg/g for HDA-S-Triazines@MCM-48 and DA-S-Triazines@MCM-48, respectively. The equilibrium data were fitted to nonlinear Freundlich, Temkin and Langmuir models, while a better fit was obtained by Freundlich model. According to the kinetic parameters, the sorption process was rapid. To selective sorption of Ag (I) from aqueous solution and real wastewater, the pore size of MCM-48 was exactly adjusted by changing the amount of DA-S-Triazines ligand. The results illustrated that the selective sorption of Ag (I) increased by increasing the amount of DA-S-Triazines ligand grafted on MCM-48 mesoporous silica. The results of sorption-desorption proved the economic synthesis and practical application of DA-S-Triazines@MCM-48 for sorption of Ag (I) from wastewater. DA-S-Triazines@MCM-48 as a potential sorbent showed high sorption capacity for sorption of Ag (I) from electroplating industry wastewater.
It is well known that the number of particles should be scaled up to enable industrial scale simulation. The calculations are more computationally intensive when the motion of the surrounding fluid is considered. Besides the advances in computer hardware and numerical algorithms, the coupling scheme also plays an important role on the computational efficiency. In this study, a particulate immersed boundary method (PIBM) for simulating the fluid-particle multiphase flow was presented and assessed in both two- and three-dimensional applications. The idea behind PIBM derives from the conventional momentum exchange-based Immersed Boundary Method (IBM) by treating each Lagrangian point as a solid particle. This treatment enables Lattice Boltzmann Method (LBM) to be coupled with fine particles residing within a particular grid cell. Compared with the conventional IBM, dozens of times speedup in two-dimensional simulation and hundreds of times in three-dimensional simulation can be expected under the same particle and mesh number. Numerical simulations of particle sedimentation in Newtonian flows were canducted based on a combined LBM-PIBM-Discrete Element Method (DEM) scheme, showing that the PIBM can capture the feature of particulate flows in fluid and is indeed a promising scheme for the solution of the fluid-particle interaction problems.
Zhang, H.; Trias, F. X.; Gorobets, A.; Oliva, A.; Yang, D.; Tan, Y.; Sheng, Y. Powder technology Vol. 269, p. 320-336 DOI: 10.1016/j.powtec.2014.08.070 Data de publicació: 2015-01-01 Article en revista
The effect of collisions on the particle behavior in a fully developed turbulent flow in a straight square duct at Re-r = 300 is numerically investigated. The hydrodynamic modeling of the fluid phase is based on direct numerical simulation. The kinematics and trajectory of the particles as well as the collisions are described by the discrete element method. Three sizes of particles are considered with diameters equal to 50 mu m, 100 mu m and 500 mu m. Firstly, the particle transportation by turbulent flow is studied in the absence of the gravitational effect. It is found that the collisions play an important role in the particle distribution especially in the near-wall regions. The inter-particle collisions enhance the particle diffusion in the direction perpendicular to streamwise flow and make the particles distribute more uniformly near the wall. Then, the particle deposition is studied under the effect of the wall-normal gravity force in which the influence of collisions on the particle resuspension rate and the final stage of particle distribution on the duct floor are discussed, respectively. The collisions are found to have influence on the particle resuspension rate near the duct floor whereas hardly affect the particle behavior near the duct center. Under the gravitational effect the 50 mu m particles deposit more efficiently near the side walls but the 100 mu m and 500 mu m particles preferentially deposit near the center of the duct floor. Moreover, all the sizes of particles tend to concentrate near the center of the duct floor at the final stage of the particle deposition when the inter-particle collisions are considered.