Synthesis and characterization of hard magnetic composite photocatalyst—Barium ferrite/silica/titania

Lee, Seung-woo; Drwiega, Jack; Mazyck, David W.; Wu, Chang‐Yu; Sigmund, Wolfgang M.

doi:10.1016/j.matchemphys.2005.07.039

Cited by 69 publications

(38 citation statements)

References 22 publications

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“…In the desired case, the calcinations are carried out by crystallizing the amorphous titania layer into the anatase phase. The detailed procedures were shown in previous reports (Abramson et al 2009 ;Chung et al 2004 ;Lee et al 2006 ;Kostedt et al 2010 ;Song and Gao 2007 ;Fu et al 2005 ;Lou et al 2009a, b ;Li et al 2009 ;Ye et al 2010 ;Zhang et al 2009a, b ) . The resulting magnetic photocatalysts did not only gain the activity comparable to the pure titania, but could also be repeatedly reused using the external magnetic force for recovery.…”

Section: Preparation and Cyclic Applicationsmentioning

confidence: 96%

“…According to the structural model, several three-component magnetic photocatalysts were synthesized, such as g -Fe 2 O 3 /SiO 2 /TiO 2 (Chen and Zhao 1999 ;Chen et al 2001 ;Gao et al 2003 ;Tawkaew and Supothina 2008 ;Abramson et al 2009 ;Wang et al 2010 ) , Fe 3 O 4 /SiO 2 /TiO 2 (Beydoun et al 2002 ;Rose et al 2003 ;Watson et al 2005 ;Xu et al 2005Xu et al , 2008aSong and Gao 2007 ;Kurinobu et al 2007 ;Gad-Allah et al 2009 ;Wang et al 2009 ;Ye et al 2010 ) , MFe 2 O 4 /SiO 2 /TiO 2 (Shchukin et al 2004 ;Chung et al 2004 ;Fu et al 2005 ;Lee et al 2006 ;Xu et al 2007a, b ;Zhang et al 2009a ;Kostedt et al 2010 ) , and others (Belessi et al 2009 ;Li et al 2009 ;Chen et al 2009 ) . Their components are listed in Table 4.1 .…”

Section: Structure Of Magnetic Photocatalystsmentioning

confidence: 99%

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Magnetic Nano-photocatalysts: Preparation, Structure, and Application

Liu

2011

Environmental Chemistry for a Sustainable World

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Photocatalytic degradation of organic pollutants using suspended and dispersed nanosemiconductor photocatalysts in wastewater has unique advantages including high activity, low cost, solar utilization, and complete mineralization. However recovery and reuse of photocatalysts are diffi cult because fi ne particles are easily discharged in the waterfl ow. Immobilization of photocatalysts on supports such as glass and zeolite decreases activities due to the low specifi c area and slow mass transfer. Furthermore, a large amount of photocatalysts will lead to color contamination if they are released at industrial scale. Therefore, it is necessary to develop photocatalysts with separation function for reusable and cyclic application. The concept of magnetic photocatalysts with separation function was raised to benefi t from high activity and enable nanosemiconductor photocatalysts to be reused.

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Section: Preparation and Cyclic Applicationsmentioning

confidence: 96%

Section: Structure Of Magnetic Photocatalystsmentioning

confidence: 99%

Magnetic Nano-photocatalysts: Preparation, Structure, and Application

Liu

2011

Environmental Chemistry for a Sustainable World

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“…Typically, a photocatalytic reaction is always conducted in a suspension of submicrometer-sized TiO 2 , and therefore an additional separation step is required to remove the photocatalyst from the treated waters [11][12][13][14]. This presents a main drawback for their widespread applications.…”

Section: Introductionmentioning

confidence: 99%

Synthesis of magnetically separable N, La-doped TiO2 with enhanced photocatalytic activity

Yang

et al. 2015

Separation and Purification Technology

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a b s t r a c tA magnetically separable nitrogen and lanthanum co-doped photocatalyst c-Fe 2 O 3 @SiO 2 @N,La-TiO 2 (FST) with a typical superparamagnetic property was prepared by an effective three-step approach. Specifically, the preformed monodisperse c-Fe 2 O 3 nanoparticles were used as templates for directing the sequential deposition of SiO 2 layer by modified Stöber method and subsequent N,La-TiO 2 layer by hydrothermal method. During the hydrothermal assisted TiO 2 deposition, the interior black Fe 3 O 4 nanoparticles were converted into dark-brown c-Fe 2 O 3 nanoparticles. FST showed a ternary structure with a core of c-Fe 2 O 3 , a SiO 2 mesosphere and a N,La-TiO 2 (anatase) crust. SiO 2 layer can prevent effectively the transfer of charges from TiO 2 to c-Fe 2 O 3 , which avoids electrons and holes recombination at the interface. SiO 2 inter-layer is also a good adsorbent for dye molecules, FST showed higher photocatalytic activity than c-Fe 2 O 3 @N,La-TiO 2 (FT). FST is photoactive under both UV and visible light irradiation and can be easily separated from a slurry in photoreactor by the application of an external magnetic field.

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“…Hard magnetic materials are more difficult to magnetize, but once magnetized can maintain their magnetic characteristics as opposed to the spontaneously induced magnetic behavior of soft magnetic materials. However, they may suffer from some of the same oxidation-related decrease in magnetic properties [14]. Hard magnetic materials can be recovered using a magnet just as soft magnetic materials, but they have the additional capability of being agitated using an oscillating magnetic field gradient.…”

Section: Introductionmentioning

confidence: 99%

“…Beydoun also proposed to solve this problem using a silica insulating layer, but instead performed this coating using the Stöber method with a tetraethylorthosilicate (TEOS) silica precursor [8]. Lee [14] and Kostedt [2] used the Stöber method as well, but chose to use isopropanol instead of ethanol as a solvent, which is likely to produce larger silica particles. Lee found that this method produced a robust silica layer and prevention of photodissolution indicated by ICP analysis and TEM imaging.…”

Section: Introductionmentioning

confidence: 99%

A high surface area magnetic photocatalyst with controlled pore size

Kostedt

Byrne

Mazyck

2010

Env Prog and Sustain Energy

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Magnetic photocatalysts have the benefit of recoverability or even confinement/agitation using an oscillating magnetic field. A high surface area magnetic photocatalyst (HSAMP) was developed consisting of silica-coated barium ferrite and Degussa P25 titanium dioxide dispersed in an acid catalyzed silica xerogel. Through modifying the concentration of hydrofluoric acid catalyst during synthesis, three types of HSAMPs were developed with resulting BET specific surface areas of 374, 543, and 550 m 2 /g. These HSAMPs were assessed for their photocatalytic activity by oxidizing a 6.5 mg/L phenol solution in comparison to Degussa P25 alone. The resulting extent of photocatalysis was greater for the HSAMP than for Degussa P25 although the latter demonstrated a more rapid removal of the phenol parent compound. The HSAMP was capable of removing nearly 100% of the nonpurgeable dissolved organic carbon for 6 repeated uses. Nearly 99% of the HSAMP mass was recoverable with a permanent magnet.

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Synthesis and characterization of hard magnetic composite photocatalyst—Barium ferrite/silica/titania

Cited by 69 publications

References 22 publications

Magnetic Nano-photocatalysts: Preparation, Structure, and Application

Magnetic Nano-photocatalysts: Preparation, Structure, and Application

Synthesis of magnetically separable N, La-doped TiO2 with enhanced photocatalytic activity

A high surface area magnetic photocatalyst with controlled pore size

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