Limits...
Direct Synthesis of Novel and Reactive Sulfide-modified Nano Iron through Nanoparticle Seeding for Improved Cadmium-Contaminated Water Treatment.

Su Y, Adeleye AS, Huang Y, Zhou X, Keller AA, Zhang Y - Sci Rep (2016)

Bottom Line: Syntheses monitoring experiments show that seeding accelerates the reduction rate from Fe(2+) to Fe(0) by 19%.Both X-ray diffraction and Mössbauer analyses further confirm that increased nanoparticle seeding results in formation of more Fe(0) crystals.The synthesized nanohybrid has high cadmium removal capacity and holds promising prospects for treatment of metal-contaminated water.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Pollution Control and Resources Reuse, Tongji University, Shanghai 200092, China.

ABSTRACT
Magnetic sulfide-modified nanoscale zerovalent iron (S-nZVI) is of great technical and scientific interest because of its promising application in groundwater remediation, although its synthesis is still a challenge. We develop a new nanoparticle seeding method to obtain a novel and reactive nanohybrid, which contains an Fe(0) core covered by a highly sulfidized layer under high extent of sulfidation. Syntheses monitoring experiments show that seeding accelerates the reduction rate from Fe(2+) to Fe(0) by 19%. X-ray adsorption near edge structure (XANES) spectroscopy and extended X-ray absorption fine structure analyses demonstrate the hexahedral Fe-Fe bond (2.45 and 2.83 Å) formation through breaking down of the 1.99 Å Fe-O bond both in crystalline and amorphous iron oxide. The XANES analysis also shows 24.2% (wt%) of FeS with bond length of 2.4 Å in final nanohybrid. Both X-ray diffraction and Mössbauer analyses further confirm that increased nanoparticle seeding results in formation of more Fe(0) crystals. Nano-SiO2 seeding brings down the size of single Fe(0) grain from 32.4 nm to 18.7 nm, enhances final Fe(0) content from 5.9% to 55.6%, and increases magnetization from 4.7 to 65.5 emu/g. The synthesized nanohybrid has high cadmium removal capacity and holds promising prospects for treatment of metal-contaminated water.

No MeSH data available.


Related in: MedlinePlus

Fe2+ trend in FeCl3•6H2O solution during titration (all the collected samples were passed through a 0.22 um filter.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4837343&req=5

f1: Fe2+ trend in FeCl3•6H2O solution during titration (all the collected samples were passed through a 0.22 um filter.

Mentions: As can be seen in Fig. 1, the synthesis process involves the reduction of ferric ions to ferrous ions first (equation 1), and then nucleation (equation 2)13. The formation of pristine nZVI follows the zero-order reaction model30, which is quite interesting. According to the Finke-Watzky 2-step theory, a slow, continuous nucleation and fast autocatalytic growth should be observed, resulting in a sigma plot22. However, in the case of nZVI synthesis system without a stabilizer, nZVI agglomerate severely, which means autocatalytic growth is much faster than nucleation. In other words, the reaction rate of eq.1 determines the rate of nanoparticle formation. However, formation of S-nZVI is not well-described by a zero-order reaction model. We did not observe any significant influence of reactor material on nucleation. However, nano-SiO2 seeding accelerated iron reduction by about 19%, calculated by comparing the rate between S-nZVI (in glass) and FeSSi (with 0.048 g nano-SiO2) systems. Similar trend of Fe2+ concentration was also observed in the synthesis system with nano TiO2 or nano Al2O3 addition (Fig. S1).


Direct Synthesis of Novel and Reactive Sulfide-modified Nano Iron through Nanoparticle Seeding for Improved Cadmium-Contaminated Water Treatment.

Su Y, Adeleye AS, Huang Y, Zhou X, Keller AA, Zhang Y - Sci Rep (2016)

Fe2+ trend in FeCl3•6H2O solution during titration (all the collected samples were passed through a 0.22 um filter.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4837343&req=5

f1: Fe2+ trend in FeCl3•6H2O solution during titration (all the collected samples were passed through a 0.22 um filter.
Mentions: As can be seen in Fig. 1, the synthesis process involves the reduction of ferric ions to ferrous ions first (equation 1), and then nucleation (equation 2)13. The formation of pristine nZVI follows the zero-order reaction model30, which is quite interesting. According to the Finke-Watzky 2-step theory, a slow, continuous nucleation and fast autocatalytic growth should be observed, resulting in a sigma plot22. However, in the case of nZVI synthesis system without a stabilizer, nZVI agglomerate severely, which means autocatalytic growth is much faster than nucleation. In other words, the reaction rate of eq.1 determines the rate of nanoparticle formation. However, formation of S-nZVI is not well-described by a zero-order reaction model. We did not observe any significant influence of reactor material on nucleation. However, nano-SiO2 seeding accelerated iron reduction by about 19%, calculated by comparing the rate between S-nZVI (in glass) and FeSSi (with 0.048 g nano-SiO2) systems. Similar trend of Fe2+ concentration was also observed in the synthesis system with nano TiO2 or nano Al2O3 addition (Fig. S1).

Bottom Line: Syntheses monitoring experiments show that seeding accelerates the reduction rate from Fe(2+) to Fe(0) by 19%.Both X-ray diffraction and Mössbauer analyses further confirm that increased nanoparticle seeding results in formation of more Fe(0) crystals.The synthesized nanohybrid has high cadmium removal capacity and holds promising prospects for treatment of metal-contaminated water.

View Article: PubMed Central - PubMed

Affiliation: State Key Laboratory of Pollution Control and Resources Reuse, Tongji University, Shanghai 200092, China.

ABSTRACT
Magnetic sulfide-modified nanoscale zerovalent iron (S-nZVI) is of great technical and scientific interest because of its promising application in groundwater remediation, although its synthesis is still a challenge. We develop a new nanoparticle seeding method to obtain a novel and reactive nanohybrid, which contains an Fe(0) core covered by a highly sulfidized layer under high extent of sulfidation. Syntheses monitoring experiments show that seeding accelerates the reduction rate from Fe(2+) to Fe(0) by 19%. X-ray adsorption near edge structure (XANES) spectroscopy and extended X-ray absorption fine structure analyses demonstrate the hexahedral Fe-Fe bond (2.45 and 2.83 Å) formation through breaking down of the 1.99 Å Fe-O bond both in crystalline and amorphous iron oxide. The XANES analysis also shows 24.2% (wt%) of FeS with bond length of 2.4 Å in final nanohybrid. Both X-ray diffraction and Mössbauer analyses further confirm that increased nanoparticle seeding results in formation of more Fe(0) crystals. Nano-SiO2 seeding brings down the size of single Fe(0) grain from 32.4 nm to 18.7 nm, enhances final Fe(0) content from 5.9% to 55.6%, and increases magnetization from 4.7 to 65.5 emu/g. The synthesized nanohybrid has high cadmium removal capacity and holds promising prospects for treatment of metal-contaminated water.

No MeSH data available.


Related in: MedlinePlus