جستجوی مقالات مرتبط با کلیدواژه « سینتیک جذب » در نشریات گروه « مواد و متالورژی »

Industrial wastewater treatment and recycling the treated water are drawn to attention. In this study, the removal of heavy metal cations (e.g. Cu, Ni, Co) as an important pollutants, has been investigated by applying the Nylon6/zirconia nano-composite absorbent. Nano-composite membranes containing different amount of zirconia nano-particles (NPs) were synthesized via electrospinning method. To study the microstructure and functional molecule groups of nano-absorbent, SEM and FTIR techniques were used, respectively. The results showed that the average diameter size of fibers and surface porosity decreased from 387 to 105 nm and 83.1 to 65.6 % with increasing the zirconia content, respectively. Furthermore, zirconia NPs were distributed heterogeneously and also electrospinning defects such as zirconia agglomerates were observed in the mat. Adding the zirconia NPs did not affect the functional molecule groups of Nylon6. According to the homogenous distribution and also creation of active sites by zirconia NPs, the ratio of zirconia to Nylon6 equals to 0.88 (g/g) was selected as the optimized composition. Water contact angle variations on the surface of nano- absorbent indicated that the mentioned surface had hydrophobic behavior at the beginning time of contact and then it switched to the hydrophilic manner. Kinetic study on the adsorption of heavy metal cations showed that it was followed by first-pseudo order model. The maximum adsorption was recorded 9.6, 8.7 and 4.8 mg/cm2 respect to the Cu, Ni, and Co cations. It suggests that the Nylon6/zirconia nano-composite has high efficiency to adsorb heavy metal pollutants. Eventually, the water recycling will be achieved by development of polymer-ceramic nano-composite.

Chromium is one of the most important pollutants in aquatic environments that, at high concentrations, cause different ecological threats and health risks for human society. Thus, it is very necessary to remove it from aquatic Solutions. Therefore, the aim of this study was to investigate the efficiency of removal hexavalent chromium by biological absorbers (oak, pomegranate, and egg shell), and the study of isotherm and kinetics of their absorption. In order to achieve to the optimal removal of chromium, the variables affecting on adsorption process such as pH, coagulation speed, reaction time and initial concentration of adsorbent material were investigated. Also, for adsorption isotherms and kinetics study the first order and second order pseudo kinematic models and Langmuir and Freundlich isotherms were used. The results showed removal efficiency of Cr increased with increasing the dose of adsorbent, contact time, and coagulation speed. But by changing the pH, depending on the absorbent type, the absorption efficiency was changed and the highest absorption efficiency for egg, oak and pomegranate shell was obtained at pH 10, 4 and 2, respectively. The kinetics was second-order for all three adsorbents and absorption isotherms from the Freundlich model for egg and pomegranate and for oak shell was more consistent with Langmuir model. According to the obtained results can be concluded that egg, oak and Pomegranate shell respectively, have high more efficiency in removing hexavalent chromium from aqueous solutions.