JOURNAL OF SEPARATION SCIENCE AND ENGINEERING
Year:2019 | Volume:11 | Issue:1 |Papers Count:9

In this research, the effect of microwave radiation on the surface chemistry and liberation degree of copper sulfide minerals (Sarcheshmeh and Palangi ores) was investigated. In flotation studies on the effect of microwave radiation on the surface chemistry, after 90 seconds radiation, the concentrate grade and recovery of the Sarcheshmeh samples increased 7 and 2 percent; respectively but the concentrate grade and recovery of the Palangi samples decreased 4 and 8 percent, respectively. Also, in flotation studies on the effect of microwave radiation on the liberation degree, after 180 seconds radiation, the concentrate grade and recovery of the Sarcheshmeh samples increased 4 and 6 percent respectively but for the Palangi samples, a same increase in the grade and recovery was obtained in 600 seconds of microwave radiation. Furthermore, flotation rate constant of the Sarcheshmeh and Palangi samples increased 0. 2 and 0. 1 per minute respectively, after 120 seconds microwave radiation.

In this research, the effect of multiwall carbon nanotubes (MWCNTs) on the performance of polyvinyl chloride (PVC) membrane in the filtration of humic acid solution was investigated. The FESEM results showed that the number of surface pores in nanocomposite membranes is more than that of PVC membrane. The tensile strength and abrasion resistance of membranes increased with increasing MWCNTs up to 053 wt. %. It was also observed that water flux of membrane containing 053 wt. % MWCNTs increases up to 48457 L/m2h. The decrease of water contact angle from 88568 for PVC membrane to 70528 for 053 wt. % MWCNTs membrane showed that the hydrophilicity of membranes increases with increasing MWCNTs. It was also found that the rejection of humic acid solution with MWCNTs membranes is more than that of PVC membrane. The analysis of fouling mechanism of membranes revealed that the cake formation model is dominant mechanism for all membranes and cake filtration-complete blockage model fits the volume-time data.

In this study, to evaluate the performance of aqueous diethanolamine (DEA) CO2 absorption process from flue gas, the volumetric overall gas phase mass transfer coefficient (KGaV) and the volumetric mass flux (NAaV) was investigated under different operating conditions, including: inlet solvent temperature 35-55 ° C, the CO2 concentration in flue gas 5-15 vol. %, flue gas flow rate 50-100 lit/min, solvent flow rate 0. 75-1. 25 lit/min, DEA concentration 15-25 wt. % and reboiler heat load: 1. 4-2. 2 kW. To evaluate the results and optimize the conditions, the Box-Behnken Response Surface methodology was used. The results showed that by increasing solvent flow rate, gas flow rate, reboiler heat load and DEA concentration in the solvent, the NAaV and KGaV values were increased. However, increasing the CO2 concentration in the flue gas increased NAaV, and decreased KGaV. The temperature changes and carbon dioxide concentration through the absorption column showed that carbon dioxide absorption was more in the higher ratio of solvent flow to gas flow rate. However, increasing the length of the column increases the CO2 absorption. Finally, optimization of the operating conditions has been done. The maximization of NAaV and KGaV simultaneously was considered as objective function. At optimal operating conditions, the NAaV and KGaV values reached 15. 01 (kmol/h. m3) and 3. 07 (kmol / h. m3. kPa), respectively.

The adsorption modeling of Methylene Blue dye (MB+) on the modified tea waste (TW) with anionic surfactant (SDS) was performed by the artificial neural network. The FTIR and EDS analyses were used to investigate the presence of SDS on the adsorbent surface and it was determined that the SO3-anions help to MB+ adsorption by the ion exchange mechanism. The adsorption isotherm data were fitted to Langmuir and Freundlich isotherm equations and the Langmuir adsorption capacity (Qmax) was calculated respectively, equal to 124. 3 and 156. 2 mg/g for TW and STW. It was observed that the adsorption kinetics of MB follows the pseudo-second-order kinetic model. The findings of this investigation suggest that physical adsorption also plays a role in controlling the sorption rate of MB. The feedforward ANN model with 5 input parameters and one hidden layer having 15 neurons was designed to predict the adsorptive behavior of sorbents, and it was observed that the model is able to predict the MB removal percentage for the test data series with great R2>0. 97.

In this research, the performance of photocatalyst/membrane process hybrid system was investigated for the ammonia removal from the wastewater. The prepared membranes were ultrafiltration (UF) using the polyethersulfone (PES) by the phase inversion method. Synthetic fumarate alumoxane nanoparticle was used as the additive in the preparation of membrane. The photocatalyst was zinc oxide (ZnO) fixed on a light expanded clay aggregate support named LECA. The effect of the parameters containing ammonia initial concentration, nanoparticle content and the treatment process duration on the ammonia removal was investigated. The photocatalyst and membrane systems were employed separately and their performance including the flux and rejection was compared with the hybrid system. The results showed that the photocatalyst system was able to remove the ammonia at high flux level, well. By consideration of the ammonia flux and its removal percentage, the best performance was obtained for the membrane prepared by the PES with 2 wt. % nanoparticle. In hybrid system, firstly, the ammonia was reached to the low concentration and then, the membrane process removed this low concentration of ammonia.

According to the experimental observations, airlift reactor with net draft tube provided a suitable medium for microbial reactions, hence improved process efficiency and is a recommended bioreactor for wastewater bio-treatment. However, modeling and simulation of biodegradation process in this special bioreactor seems essential to proper design and optimization of the performance of the reactor. In this work, the biodegradation process of phenol with Ralstonia eutropha cells and microbial growth is simulated in a lab-scale airlift reactor with net draft tube using computational fluid dynamics (CFD). The k-ɛ model, as the most common model used for description of turbulent flow, is used for the simulation of the present bubbly flow. Flow pathlines in the riser and downcomer sections of the airlift reactor is simulated and the phenol concentration variations and biomass distribution in different inlet conditions were demonstrated by simulated concentrations contours. Good agreement was find between simulation and experimental results which validated the model and proved the accuracy of the simulation.

The aim of this present work is the synthesis of the functionalized magnetic activated carbon derived from peach stone for simultaneous removal of heavy metal ions from aqueous solutions. The various tests including XRD, BET, XRF, Boehm, VSM and FTIR were applied to characterize the prepared nano-adsorbent. The results showed the well dispersed spherical magnetite nanoparticles with size of 20 nm were formed over the nano-adsorbent while the surface area was calculated to be 325 m2/g. The Designed experimental data by employing response surface method indicated that the adsorption temperature and pH have the synergic effect on the competitive adsorption of Pb (II), Cr (VI) and Hg (II) in the liquid phase. The maximum removal efficiencies were calculated to be 9115, 62105 and 8217 for Pb (II), Cr (VI) and Hg (II) at the optimal operating conditions, respectively.

Currently water saving and recycling is necessary for construction and development of mineral processing industry, affected by water resources restriction, the cast of waste accumulation and environmental consequences. Thickener is one of the most important elements at water recovery from waste water. In this study, first operating thickener condition is investigated. Computational fluid dynamics is used to simulate thickener operation with the approach of water saving increasement and the simulation is validated by conventional experiments. Devise’ s failure is detected in inability of feedwell at mixing the fluid currents and flocculants. Thickeners capacity increasement due to changes in feed load from design to operating condition is discussed and two short term solution based on flocculant dosage change and long term solution based on feedwell design are presented. 4 new feedwells are designed compatible with operating condition in order to optimize the thickener. The new feedwells by properties of surface dilution (feedwell No. 3) and underground dilution and converging output current (feedwell No. 4) are introduced as optimized feedwells. In order to deployment any of them respectively, water saving will be more than 1. 07 and 1. 34 million m^3 per a year. One of the other advantages of these feedwells is overflow discharge water clarification or in other words high solid concentration at underflow discharge.