جستجوی مقالات مرتبط با کلیدواژه "magnetic nano-adsorbent" در نشریات گروه "شیمی"

Recently adsorption by using of modified nano-adsorbents as one of the methods of separating heavy metals from wastewater has been attracted a lot of attention due to the simplicity and high efficiency of the process. In this work, at first a graphene-oxide-based magnetic nanostructure modified by tryptophan was synthesized. The synthesized magnetic graphene oxide has a high absorption capacity for Cu(II) ion (i.e., 118 mg g-1) due to the presence of nitrogen groups of tryptophan exist on the surface of adsorbent. Kinetic parameters and contact time were optimized, and the results showed that the optimal contact time is 60 minutes. Absorption kinetic studies were performed using pseudo-first-order and pseudo-second-order models. The findings indicated that the pseudo-second-order model with a higher regression coefficient (R2=0.9978), compared to the pseudo-first-order model (R2=0.9942), describes the test data better. The adsorption kinetics’ adherence to the pseudo-second-order model demonstrated that the rate-determining step is a chemical interaction. In order to investigate the thermodynamics of absorption, the effects of temperature on the absorption process were explored by using of Van’t Hoff equations, and the results showed that the absorption process is endothermic.

Dyes are scientifically and generally a new type of environmental pollutions, which has caused worldwide concern. Many research has been done in this field to remove dyes from wastewater based on the adsorption process via nano-adsorbents. This study described the synthesis of a new magnetic nano-adsorbent based on chitosan hydrogel beads to remove methylene blue as the cationic dye from aqueous solutions. Chitosan hydrogel beads were cross-linked with cellulose and synthesized in the presence of magnetic bentonite nanoparticles (Fe3O4\Bent). Fe3O4\Bent nanoparticles were obtained from the synthesis of Fe3O4 magnetic nanoparticles in the presence of bentonite nanoclay by co-precipitation and in situ method. The structure of nano-adsorbents were investigated by FT-IR, XRD, FE-SEM, TEM, and VSM techniques. The adsorption capacities of hydrogel beads for Methylene blue dye were studied via different important parameters including the effect of pH, contact time, the effect of initial dye concentration and the effect of temperature. The results showed that the kinetic data and adsorption isotherm were best-correlated to the pseudo-second-order model and Langmuir model, respectively. The thermodynamic data (ΔG, ΔS, and ΔH) indicated that the adsorption process was spontaneous, favorable and endothermic.