Adsorption of chromium (VI) ion using zeolite NaA/Fe3O4 composite derived from rice husk ash

In this study, zeolite NaA was fabricated from rice husk ash before combining with Fe3O4 to form a magnetic NaA/Fe3O4 composite. NaA/Fe3O4 composite was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), field emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), and Brunauer Emmett Teller (BET). The surface area and the pore size of zeolite NaA/Fe3O4 was 24.11 m2.g−1 and 23.04 Å. In addition, batch adsorption studies were carried out for the removal of chromium (VI) ion in aqueous solution. The effects of adsorption parameters, including pH solution, initial concentration of Cr (VI) ions, mass of adsorbent, and contact time were investigated. The maximum equilibrium adsorption capacity of zeolite NaA and NaA/Fe3O4 was 22.554 mg.g−1 and 13.722 mg.g−1, respectively. The pseudo-first order kinetic model fitted well to the experimental data. The regeneration of the adsorbent was also investigated for three cycles.

Synthesis and Characterization of NaA Zeolite Using Natural Kaolinite Clays from Nigeria by Low Temperature Hydrothermal Method

Zeolites NaA is one of the most valuable synthetic zeolites widely used as ion-exchange material, catalysts, and adsorbents in industry. There is therefore need to adopt a more energy-efficient route for its synthesis from low-cost and sustainable raw materials. In this present work, zeolites Na-A was synthesized from natural kaolinite clays obtained from three selected regions (Ikere, Okpella and Kankara) in Nigeria. The as-received kaolinite clays (IKclay, OKclay and KAclay) were initially beneficiated thoroughly to obtain pure powders (˂75 μm). The processed kaolinite clay powders were then subjected to heating in a muffle furnace at 850oC for 3 h at a heating rate of 10oC/min to convert the kaolinite clays to their respective metakaolins. The obtained metakaolins were then reacted with NaOH solutions at varying concentrations of 3.0 and 4.0M respectively using a low temperature hydrothermal transformation to obtained Zeolites Na-A powders. The obtained zeolites were then analyzed by scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS) and Fourier-transform infrared spectroscopy (FT-IR). The results showed that zeolite NaA is produced with mixture of hydroxysodalite (HS) while the EDS revealed the presence of Si, Al, O and Na indicating chemical constituents of typical zeolite NaA. All the tested kaolinite clays are therefore suitable for preparation of zeolite NaA as cheaper source of silica and aluminum.

Synthesis and Characterization of Magnetic Fe3O4/Zeolite NaA Nanocomposite for the Adsorption Removal of Methylene Blue Potential in Wastewater Treatment

In this research, the magnetic Fe3O4/zeolite NaA nanocomposite (Fe3O4/ZA), Fe3O4 nanoparticles, and zeolite NaA have been synthesized by facile hydrothermal methods for adsorption removal of methylene blue from aqueous solution. The as-synthesized Fe3O4/ZA nanocomposite was characterized by X-ray diffraction (XRD), MicroRaman analysis, Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, X-ray fluorescence (XRF), N2 adsorption isotherms (BET), and UV-VIS analysis. The results show that with a small weight loading of Fe3O4, the ∼3.3% Fe3O4/ZA sample exhibits a high adsorption capacity (∼40.36 mg·g−1) and removal efficiency (∼96.8%) compared to that of the zeolite NaA (∼32.99 mg·g−1 and 79.11%, respectively). Interestingly, the removal efficiency and the adsorption capacity increase rapidly with the increase of adsorption time (10–60 minutes) and Fe3O4 loading (∼3.3–9.3% wt.) in the Fe3O4/ZA composition. The adsorption mechanism of MB molecules of the Fe3O4/ZA can be addressed at the combination of the interaction between active sites on the surfaces and edges of the invert spinel ferrite Fe3O4 nanoparticles and zeolite NaA with MB molecules. Our approach provides a simple, efficient, and scalable synthesis process that render practical applications of the magnetic Fe3O4/ZA nanocomposite as a lower-cost adsorbent for wastewater treatment.

ZEÓLITA NaA SINTETIZADA SOBRE FIBRA DE VIDRO COMO ESTRATÉGIA PARA OTIMIZAÇÃO DO ABRANDAMENTO DE ÁGUAS DURAS

NaA ZEOLITE SYNTHESIZED OVER FIBERGLASS AS A STRATEGY FOR OPTIMIZING HARD WATER SOFTENING. Zeolite NaA has been successfully synthesized over glass fiber surface previously activated by alkaline treatment. By varying the time of the treatment and the amount of silica and alumina precursors used in the reaction mixture, a sample with higher zeolite concentration could be obtained. This material was evaluated for water softening process as an alternative substitute for the use of the zeolite in its powder form, in which several drawbacks related to recovery and reuse limit its application. Water softening experiments, carried out in a continuous flow system, with a column containing the glass fiber-zeolite NaA, showed high performance in decreasing the Ca2+ ions, with complete removal achieved for 20 mL of simulated hard water (Ca2+ 100.0 mg L– ¹) by using 200 mg of the sample in form of column (10 mm diameter × 300 mm high). The sample maintained this performance in a wide range of pH (3.0-9.0), and also presented a feasible regenerability, with no decrease in its performance during the first four cycles of use, reaching 87.3% of efficiency over the tenth cycle.

Methanol Dehydration to Dimethyl Ether over Modified γ-Al2O3 with Acid, Base and Zeolite (NaA and NaX)

The effect of acids, bases, zeolite NaA and zeolite NaX impregnation to g-Al2O3 on the catalyst characteristics and activity against methanol dehydration reaction were investigated. The catalyst characteristics include N2 physisorption, X-ray diffraction (XRD), and temperature-programmed desorption of ammonia (NH3-TPD) in addition to catalytic dehydration of methanol performed in a micro fixed-bed reactor at 270°C and 1 atm. The results of XRD characterization showed no changes related to the modification of alumina over acids, bases, and zeolite NaA and zeolite NaX. Therefore, the modification did not have any effect on the crystalline structure of alumina. The textural and surface acidity of g-Al2O3 changed post addition of acids, bases, zeolite NaA and zeolite NaX. NH3-TPD analysis results demonstrated that synthesized g-Al2O3 has three types of acid sites: weak, medium, and strong; however, the weak acid sites were not observed on alumina catalysts modified phosphate, KOH, zeolite NaA, and zeolite NaX. Furthermore, the concentration of strong acid sites increased in the catalyst containing KOH. The catalytic test results showed that the untreated g-Al2O3 catalyst gave prominent activity in dehydration of methanol compared to the treated catalyst following the number and strength of acid sites.

Enhancement of CO2 Adsorption Containing Zinc-ion-exchanged Zeolite NaA Synthesized from Rice Husk Ash

Carbon dioxide is main causes the greenhouse effect and it contributes to global warming. Zeolite NaA is an excellent adsorbent among other materials but its potential as a carbon dioxide adsorption still needs to be developed. Therefore, this research was to synthesize zeolite NaA from rice husk ash under different temperatures and crystallization times. The synthesized zeolite NaA was modified with zinc by an ion exchange method. Adsorbents were tested for the carbon dioxide adsorption at different operating temperatures and flow rates. The results showed that the zeolite NaA was successfully synthesized from rice husk ash under optimal conditions of the crystallization temperature at 333.15 K and time for 2 h. The zeolite NaA can be synthesized at low crystallization temperature and time resulted in this adsorbent has low cost while achieving high efficiency. The results of zeolite NaA modification with zinc playing a key role to increase the BET surface area, micropore volume and total pore volume resulted in an increase of carbon dioxide adsorption capacity. High carbon dioxide adsorption at 89.08% with the operating temperature at 573.15 K and carbon dioxide flow rate of 1 L/h were shown with 5 wt.% zeolite NaA.