scholarly journals Removal of Zinc from Aqueous Solutions by Magnetite Silica Core-Shell Nanoparticles

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
Masoomeh Emadi ◽  
Esmaeil Shams ◽  
Mohammad Kazem Amini
Keyword(s):  
Aqueous Solutions ◽  
Sol Gel ◽  
Freundlich Isotherm ◽  
Second Order ◽  
Isotherm Models ◽  
Core Shell ◽  
Order Kinetic ◽  
Shell Nanoparticles ◽  
Silica Core ◽  
Core Shell Nanoparticles

Magnetite silica core-shell nanoparticles (Fe3O4-SiO2) were synthesized and evaluated as a nanoadsorbent for removing Zn(II) from aqueous solutions. The core-shell nanoparticles were prepared by combining coprecipitation and sol-gel methods. Nanoparticles were characterized by X-ray diffraction, transmission electron microscopy (TEM), and FT-IR. The magnetization values of nanoparticles were measured with vibrating sample magnetometer (VSM). The adsorption of Zn(II) ions was examined by batch equilibrium technique. The effects of pH, initial Zn(II) concentration, and contact time on the efficiency of Zn(II) removal were studied. The equilibrium data, analyzed by using Langmuir and Freundlich isotherm models, showed better agreement with the former model. Using the Langmuir isotherm model, maximum capacity of the nanoadsorbent for Zn(II) was found to be 119 mg g−1at room temperature. Kinetic studies were conducted and the resulting data were analyzed using first- and second-order equations; pseudo-second-order kinetic equation was found to provide the best correlation. The adsorption and sedimentation times were very low. The nanoadsorbent can be easily separated from aqueous solution by a magnet. Repeated adsorption acid regeneration cycles were performed to examine the stability and reusability of the nanoadsorbent. The result of this study proved high stability and reusability of Fe3O4-SiO2as an adsorbent for Zn(II) ions.

Synthesis and Characterization of Silylated Kaolinite/Silica Core–Shell Nanoparticles

2011 ◽  
Vol 105-107 ◽  
pp. 1760-1763
Author(s):  
Qian Zhang ◽  
Bai Mei Zhang
Keyword(s):  
Sol Gel ◽  
Core Shell ◽  
Silane Treatment ◽  
Shell Nanoparticles ◽  
Ultrafine Silica ◽  
Gel Technique ◽  
Silica Core ◽  
Kaolinite Surface ◽  
Core Shell Nanoparticles

Studies were conducted on the production of silane modified kaolinite/silica core-shell nanoparticles (SMKS). The SMKS nanoparticles were prepared via the sol–gel technique using tetraethyl oxysilane (TEOS) as the precursor to form silica shells on the surface of kaolinite particles followed with silane treatment. TEM of the unmodified kaolin (ORK) and SMKS revealed that a layer of ultrafine silica particles were deposited on the kaolinite surface to form a new kind of core–shell structure particles.

scholarly journals Evaluation of Pb (II) Adsorption from Aqueous Solutions Using Brassica nigra as a Biosorbent

2019 ◽  
Vol 13 (1) ◽  
pp. 77-92 ◽  
Author(s):  
Warren Reátegui-Romero ◽  
Walter J. Cadenas-Vásquez ◽  
María E. King-Santos ◽  
Walter F. Zaldivar Alvarez ◽  
Ricardo A. Y. Posadas
Keyword(s):  
Particle Size ◽  
Aqueous Solutions ◽  
Freundlich Isotherm ◽  
Brassica Nigra ◽  
Second Order ◽  
Lead Ion ◽  
Isotherm Models ◽  
Maximum Adsorption Capacity ◽  
Order Kinetic ◽  
Operating Variables

Objectives: The Pb non-biodegradability results in bioaccumulation in living organisms causing serious health disorders. The present study aimed to investigate the capacity of Pb (II) adsorption in aqueous solutions using the Brassica nigra species as biosorbent. Methods: The present study was conducted using a synthetic solution with three Pb (II) concentrations (5, 15, and 30 ppm). The B. nigra was suitably treated until it became dry particles. After sifting it, three ranges of grain sizes were obtained. Samples of dry particles were analyzed before and after the biosorption to analyze their topography (SEM), as well as the elements on their surface (EDS). The influence of different operating variables on the biosorption of Pb (II) were analyzed. Kinetics of Pb (II) biosorption was analyzed with pseudo first and second order models. The biosorption in the equilibrium was studied with the Langmuir isotherm and Freundlich isotherm models. Results: The biosorbent B. nigra showed to be efficient for the adsorption of Pb (II). The most influential variables in the adsorption were pH, particle size, and biosorbent/solution ratio. The optimum pH for the adsorption of lead was 5 and removed 82.10% of lead from solution at 5 ppm, 82.24% at 15 ppm and 57.95% at 30 ppm. The results for the particle size between 177 and 297 μm were 82.65% for 5 ppm, 73.71% for 15 ppm, and 53.54% for 30 ppm. The biosorbent/solution ratio of 0.6 mg/mL or the 30 mg dose of biosorbent removed 80.26% for 5 ppm, 79.32% for 15 ppm, and 59.87% for 30 ppm. Biosorption isothermal data could be well interpreted by the Langmuir model with a maximum adsorption capacity of 53.476 mg/g of lead ion on B. nigra stem and roots biomass. The kinetic experimental data was properly correlated with the second-order kinetic model (R2 = 0.9997). Thus, the best desorbing agent was HNO3 (0.1N) for Pb (II) desorption. Conclusion: Our study showed that the herb B. nigra, without any chemical treatment, can be used to remove heavy metals such as Pb (II) from water and aqueous solution.

Adsorption of Congo Red Dye from Aqueous Solutions by Montmorillonite as a Low-cost Adsorbent

2017 ◽  
Vol 16 (1) ◽  
Author(s):  
Yusef Omidi Khaniabadi ◽  
Hassan Basiri ◽  
Heshmatollah Nourmoradi ◽  
Mohammad Javad Mohammadi ◽  
Ahmad Reza Yari ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Congo Red ◽  
Low Cost ◽  
Aqueous Media ◽  
Freundlich Isotherm ◽  
Second Order ◽  
Isotherm Models ◽  
Order Kinetic ◽  
Effective Option ◽  
Pseudo Second Order

AbstractIn this study, the sorption of Congo red (CR), as a toxic dye, from aqueous media was investigated using montmorillonite (MMT) as a low-cost adsorbent. The influence of several factors such as contact time, pH, adsorbent dosage, dye content, and ionic strength was investigated on the dye removal. MMT was characterized by Fourier transformed infrared (FTIR) spectroscopy and X-ray diffractometer (XRD). Different kinetic and isotherm models including pseudo-first and pseudo-second order kinetic and Langmuir and Freundlich were applied to analyze experimental data, respectively. The results showed that the data were well fitted by pseudo-second-order kinetic and Freundlich isotherm models. The optimum conditions for the sorption of CR were achieved over 40 min and at pH=2. According to the results of the present study, MMT can be used as a low-cost, eco-friendly and effective option for the adsorption of CR from aqueous solutions.

scholarly journals Multi-Component Adsorption of Benzene, Toluene, Ethylbenzene, and Xylene from Aqueous Solutions by Montmorillonite Modified with Tetradecyl Trimethyl Ammonium Bromide

2013 ◽  
Vol 2013 ◽  
pp. 1-10 ◽  
Author(s):  
H. Nourmoradi ◽  
Mehdi Khiadani ◽  
M. Nikaeen
Keyword(s):  
Experimental Data ◽  
Aqueous Solutions ◽  
Structural Changes ◽  
Freundlich Isotherm ◽  
Isotherm Models ◽  
Ammonium Bromide ◽  
Order Kinetic ◽  
Multicomponent Adsorption ◽  
Benzene Toluene ◽  
Kinetic And Isotherm Models

Multicomponent adsorption of benzene, toluene, ethylbenzene, and xylene (BTEX) was assessed in aqueous solutions by montmorillonite modified with tetradecyl trimethyl ammonium bromide (TTAB-Mt). Batch experiments were conducted to determine the influences of parameters including loading rates of surfactant, contact time, pH, adsorbate concentration, and temperature on the adsorption efficiency. Scanning electron microscope (SEM) and X-ray diffractometer (XRD) were used to determine the adsorbent properties. Results showed that the modification of the adsorbent via the surfactant causes structural changes of the adsorbent. It was found that the optimum adsorption condition achieves with the surfactant loading rate of 200% of the cation exchange capacity (CEC) of the adsorbent for a period of 24 h. The sorption of BTEX by TTAB-Mt was in the order ofB<T<E<X. The experimental data were fitted by many kinetic and isotherm models. The results also showed that the pseudo-second-order kinetic model and Freundlich isotherm model could, respectively, be fitted to the experimental data better than other available kinetic and isotherm models. The thermodynamic study indicated that the sorption of BTEX with TTAB-Mt was achieved spontaneously and the adsorption process was endothermic as well as physical in nature. The regeneration results of the adsorbent also showed that the adsorption capacity of adsorbent after one use was 51% to 70% of original TTAB-Mt.

scholarly journals Obtaining of Fe3O4@C Core-Shell Nanoparticles as an Adsorbent of Tetracycline in Aqueous Solutions

2019 ◽  
Vol 22 (suppl 1) ◽  
Author(s):  
Vivian Soares ◽  
Ana Flávia dos Santos de Moraes ◽  
Janaína dos Santos ◽  
Marina Carla Grando ◽  
Cleuzir da Luz ◽  
...  
Keyword(s):  
Aqueous Solutions ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Core Shell Nanoparticles

scholarly journals The phase diagram of colloidal silica–PNIPAm core–shell nanogels

Soft Matter ◽  
2020 ◽  
Vol 16 (2) ◽  
pp. 466-475 ◽  
Author(s):  
Lara Frenzel ◽  
Felix Lehmkühler ◽  
Michael Koof ◽  
Irina Lokteva ◽  
Gerhard Grübel
Keyword(s):  
Phase Diagram ◽  
Colloidal Silica ◽  
Core Shell ◽  
Shell Nanoparticles ◽  
Aqueous Dispersions ◽  
Structure And Dynamics ◽  
Silica Core ◽  
Core Shell Nanoparticles

We study the structure and dynamics of aqueous dispersions of densely packed core–shell nanoparticles composed of a silica core and a poly(N-isoproylacrylamide) (PNIPAm) shell as a function of temperature and concentration.

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