MINISTRYOFEDUCATION ANDTRAINING
QUYNHONUNIVERSITY

TRUONGDUYHUONG

SYNTHESISANDMODIFICATIONOFMS2(M=
Mo,W)WITHg-C3N4FORPHOTOCATALYSIS

MAJOR: PHYSICAL AND THEORETICAL
CHEMISTRYCODENo.: 9440119

DOCTORALTHESISINCHEMISTRY

BINHDINH-2021


TRUONGDUYHUONG

SYNTHESISANDMODIFICATIONOFMS2(M=
Mo,W)WITHg-C3N4FORPHOTOCATALYSIS
MAJOR: PHYSICAL AND THEORETICAL
CHEMISTRYCODENO.: 9440119
Reviewer 1:Dr. Nguyen Van
ThangReviewer 2:Assoc. Prof. Nguyen Duc
CuongReviewer3:Assoc.Prof.TranThiVanThi
Supervisor:
Assoc.Prof.VOVIEN–QuyNhonUniversity

BINHDINH–2021

DECLARATION
This thesis has been completed at Quy Nhon University, in
cooperationwithKULeuven,underthesupervisorofAssoc.Prof.VoVien.Iherebyassuret
hatthisresearchprojectismine.Alltheresultsarehonest,havebeenapprovedbycoauthorsandhave not beenreleasedbyanyoneelsebefore.
Supervisor

Author

Assoc.Prof.VOVIEN

TRUONGDUYHUONG


ACKNOWLEDGEMENTS

Firstly, from my heart, I would like to express my gratitude to both
ofmy promoters, Assoc. Prof. Vo Vien and Prof. M. Enis Leblebici not only
fortheir enthusiastic guidance, expertise and invaluable time, but also for
theirencouragement when I encountered difficulties during the time of doing
theresearch. Furthermore, from the beginning to the very end of my study
time

inKULeuven,Belgium,Icould

saythat

without

theconstant


supportfromProf.
M. Enis Leblebici my study would have not accomplished any progress as
Ihave today. Meanwhile, the belief that I have ability to do the research
fromAssoc. Prof. Vo Vien made me more energetic to overcome the tough
time onmyscientificpathway.
Another professor who inspired me a lot and that also the one always
isin my heart, Prof. Tom Van Gerven. He always gave me a warm welcome
anda

lovely

smile

that

made

me

feel

more

confident

and

relax

when


we

hadunforgetablegroupmeetingstogetheralongwithProf.M.EnisLeblebici.Iamnot
exaggerated

when

say

that

the

meeting

time

with

both

of

you

has

been


themostbeautifulmomentsthatIhaveexperiencedinmylife.Eveninthetimeofwriting this
acknowledgement,Istillfeelthathappytimeinmymind.So,itisnoteasytoexpressthatfeelinginwords,especiallyinEnglish,I
justtrytosayhowkindof youare.
Having the opportunity to study in Belgium, a heart of Europe how
canIforgetthefinancialsupportfromVLIR-UOS,BelgiumwithTEAMprojectofcode
ZEIN2016PR431

and

title

“Reinforcing

the

capabilities

of

Quy

NhonUniversity-

Vietnaminsolvinglocalproblemsbybuildingupadoctoral


trainingprogram”.Withoutthisprojectalongwiththeeffortfromalltheprojectmaker
members,

including


Prof.

Do

Ngoc

My

(Rector

of

QNU),

Prof.

NguyenTienTrung,Prof.VuThiNgan,Prof.VoVien,especiallyfromProf.MinhThoNguyen,m
ydreamcouldnotcome true.
Ialsowouldliketothankmyfriendswhostoodwithmeinanycircumstances. Those
from

Vietnam

like

Ms.

Vu


Thi

Lien

Huong,

rector

of

LeKhietHighSchoolfortheGifted,Mr.LeVanTrungchemistrygroupleaderofthe school and
alllovelycolleagues.ToPhamHoangQuan,oneofmyclosestfriendswhotaughtmesomebasicexperimentalskillsfromthe
beginning, thefact that you suddenly passed away made me could not believe, I
promise totake care of your little daughter as much as I can within my ability,
Mr. TranDuc Trung for your help in heating my samples at Dung Quat
Technology andEngineeringandencouragingmeintimewhenIhadtroubles,mystudentsQuoc Nhat and
Quang Tan for your effort to do the experiments in the schoollaboratory in
the early days for the first Vsef that we achieved the best prize,the second
group with Tuan Anh and Nguyen Khang, the third group with VuQuan and
Anh Kiet, Mr. Dinh Trong Nghia and Le Van Phuong for your timein coffee
shops whenever I need someone to talk and those who I worked
andmetinKULeuvensuchasLiefintheAdmissionOffice,AlenaintheSecretaryOffice,C
hristineforyourinstructionsinthelabandcharacterizingmysamples,Michelle for your ordering
chemicals, Ruijun for some wonderful parties,watching a football match of OH Leuven and
XPS analysis, Thomas and Glenforyoursupportinthelab,Mohammedforyourniceconversation,Joris
inMTM for your acceptance and instruction of using inert atmosphere
furnace,the CIT football team which gave me a chance to be a goalkeeper for
the

firstseasonand


thetimefrom

adefenderforthesecond,Tri

who

being

with

meall


CameloTorestoHomeVesalius,thetwonicefamilyofMr.ThanhHai&Mis.MienTrung,
Hung&Hangwithalotofsupportfromtheearlydays,TanHung(little Hung) for your unforgettable
Martini wine party and Hung, Linh, TuyetAnh, brother Giang for the last but beautiful visit. My lovely group, Ms.
Lan,ThanhTam,ToNu,ZoanAn,HuuHa,allofyouarealsostillinmymindtodayandfuture.
Now, I would like to give all of my loving heart to my wife and
twodaughtersHaKhanhandCaoNguyen,whoalwaysgivemeanunlimitedenergysour
ceandthestrongestmotivationtoovercomethedifficultiesduringthetimeofstudying.Tomybeloved
wife,youknow,yoursacrificeandhardworkingto take care our angels during the time I was
away from home is the mostvaluable thing that I have ever had, that
reminded me of the responsibility notonly to our little family but also to
myself to keep my spirit on track withoutgiving up regardless the inevitable
obstacles.

To

my


father,

you

have

alwaysbeenbesidemeonmywayinspiteofthefactthatyouhaveletusaloneonthisplanet for
sixyears,Imissyousomuch.Mama,howcanIshowhowmuchimportant you are to me when now
you are become unique for my life, you donothavedirectcontributiontomywork,butthewayyou
have overcome thebig loss made me feel that you have been hiding your broken
heart

to

help

metofocusmoreonmywork.Ialsowouldliketogivemysinceregratitudetomymotherandfather-inlawforyouruncountablesupportintermsoffinanceandemotion.MysiblingsThuy,Tai,Mis.
Tramandmybrother-in-lawBinh,allofyou

alsoinmymindfor

yoursentimentalvaluethatyougave me.
ItwouldbemybigmistakeifIdonotincludeagreatdealofefforttoreadandcor
rectmythesisfromthemembersoftheBoardofJuriesforbothPremilinaryandPublicDefenc
estothisacknowledgement.T h i s helpsmealot


to realize that my thesis still need to be further revised, especially from
thecarefulreadinganddetailedcorrectionsofthereviewer,Dr.NguyenVanThang.Addition

to this, the useful comments from secretary of the Jury Dr. Tran ThiThu Phuong also help me to pay
much more attention to the last edit beforecompleting the thesis. The others in
the Juries in many ways also gave me theencouragement and positiveenergyto
defensemythesissuccessfully.
Duetothepademic,thePublicDefencewasheldonlineandIwasatthepoint of Le
Khiet

Gifted

High

School.

There

were

some

of

my

colleagues,

theschoolleaders,myteacher(NguyenTruong)andfriends,therefore,attendedtomy defence.
Especially,

Director


of

Education

and

Training

Department

ofQuangNgaiprovinceMr.NguyenNgocThaialsopresentedthere.Thepresence
of the Director made me feel much more excited and the atmosphereofthedefence
become

much

more

formal.

I

sincerely

yoursignificantsupportinthatday.
ThankyouALL.

thank

Mr.


Thai

and

theothers

for


CONTENTS

DECLARATIONACKNO
WLEDGEMENTSLIST
OFTABLES
LISTOFFIGURES
INTRODUCTION.............................................................................................1
Chapter1.LITERATUREREVIEW....................................................................6
1.1. OVERVIEWOFCURRENTPHOTOCATALYSTS................................6
1.2. MS2-BASED(M=Mo,W)PHOTOCATALYSTS....................................8
1.2.1. StructuresofMS2(M=Mo,W)............................................................8
1.2.2. MS2-basedcomposites....................................................................10
1.2.3. Synthesismethods...........................................................................11
1.2.3.1. MS2(M=Mo,W)synthesis........................................................11
1.2.3.2. MS2/g-C3N4synthesis...............................................................12
1.3. PHOTOCATALYTIC PROCESS, LIGHT SOURCES
ANDASSESSMENTBENCHMARKS.......................................................13
1.3.1. Photocatalyticdegradationmechanism.............................................13
1.3.2. Reactionkinetics.............................................................................15
1.3.3. Adsorptionroleinphotocatalyticprocess...........................................16

1.3.4.Lightsourcesforphotocatalysis–Lightemittingdiodes(LEDs)18
1.3.5. Photocatalyticreactorassessment....................................................19
1.4. PHOTODEGRADATION OF ANTIBIOTICS AND DYES
INAQUEOUSSOLUTION..........................................................................21
1.4.1. Antibioticsphotodegradation...........................................................21
1.4.2. Dyesphotodegradation...................................................................22
1.5. PHOTOCATALYTICPILOTDESIGNOVERVIEW............................24
1.5.1. Slurryreactorsversusimmobilizedcatalystreactors...........................25
1.5.2. Photocatalystseparation.................................................................26


1.5.2.1. Catalystimmobilization...........................................................26
1.5.2.2. Catalystseparation...................................................................27
Chapter2.EXPERIMENTALSECTION......................................................28
2.1. CHEMICALSANDEQUIPMENT........................................................28
2.2. MATERIALSFABRICATION.......................................................29
2.2.1. FabricationofWS2/g-C3N4..............................................................29
2.2.2. FabricationofMoS2/g-C3N4............................................................ 31
2.3. CHARACTERIZATIONS...................................................................34
2.3.1. Materialcharacterizations...............................................................34
2.3.2. Determiningpointofzerocharge................................................34
2.3.3. Lightspectraandintensity..........................................................35
2.4. PHOTOCATALYTICEXPERIMENTS.........................................35
2.4.1. Reactionsystem........................................................................35
2.4.2. Photocatalyticactivityevaluation..............................................36
2.4.3. Calibrationcurves.....................................................................38
2.4.4. Measurement of emitted irradiance using
spectrophotometerprobe....................................................................
39
2.4.5. CODmeasurement....................................................................40

2.4.6. High performance liquid chromatography (HPLC) and
massspectrometry(MS)
40
2.4.7. Activespeciesdetermination.....................................................41
2.4.8. Oxidizingagent.........................................................................41
2.5. PILOTDESIGN..............................................................................42
2.5.1. Pilotdescriptionandoperatingprinciples...........................................42
2.5.2. Detailedinstructions........................................................................43
2.5.3. TimingprogramforArduinocircuit..................................................46
2.5.4. Sedimentationprocedureandcatalystrecoverypercentage.................46
2.6. CALCULATIONS...............................................................................47


2.6.1. Reaction rate constant and photochemical space-time
yield(PSTY)
47
2.6.2. Adsorption capacity.......................................................................47
2.6.3. Flowrate forturbulentregime..........................................................48
2.6.4. Throughput forphotocatalytic pilot................................................48
Chapter3.RESULTSANDDISCUSSION.....................................................49
3.1. MATERIALCHARACTERIZATIONS...............................................49
3.1.1. WS2/g-C3N4characterizations.........................................................49
3.1.1.1. X-raydiffraction......................................................................49
3.1.1.2. Scanning electronmicroscopy.................................................50
3.1.1.3. Energy-dispersiveX-rayelementalmapping.............................51
3.1.1.4. Transmissionelectronmicroscopy...........................................52
3.1.1.5. Infraredspectroscopy...............................................................53
3.1.1.6. Raman spectroscopy...............................................................54
3.1.1.7. X-rayphotoelectronspectroscopy.............................................55
3.1.1.8. Thermogravimetricanalysis....................................................57

3.1.1.9. UV-Visdiffusereflectancespectroscopy..................................58
3.1.2. MoS2/g-C3N4characterizations.......................................................59
3.1.2.1. X-raydiffraction......................................................................59
3.1.2.2. Infraredspectroscopy...............................................................60
3.1.2.3. X-rayphotoelectronspectroscopy.............................................61
3.1.2.4. BETSurfacearea analysis........................................................62
3.1.2.5. Thermogravimetricanalysis....................................................63
3.1.2.6. UV–vis diffusereflectance spectroscopy................................65
3.1.2.7. Energy-dispersiveX-rayelementalmapping.............................65
3.2. MATERIALPHOTOCATALYTICACTIVITY.............................67
3.2.1. Adsorption-desorption equilibriumtime........................................67
3.2.2. Photocatalyticactivitycomparisons.................................................69
3.2.3. Effectofcatalyst loading...........................................................72


3.2.4. Adsorption andphotocatalysis........................................................74
3.2.4.1. Pointofzerochargeandexistedforms ofdye molecules..............74
3.2.4.2. EffectofpHsolution,importantroleofadsorptionstep..................76
3.2.5. A new benchmark for efficiency evaluation of reaction reactor –
Photochemicalspacetimeyield..................................................................81
3.2.5.1. Calculatereactionrateconstantunderoptimalcondition..............81
3.2.5.2. PSTYcalculationsforthechosenreactionsystems.......................82
3.2.6. Mechanisminvestigation.................................................................84
3.2.6.1. Effectofoxidantconcentration..................................................84
3.2.6.2. Reactive species trapping experiments and
proposedphotocatalyticmechanism......................................................86
3.2.7. Applications...................................................................................91
3.2.7.1. Photodegradationofaselectedantibiotic,enrofloxacin................91
3.2.7.2. Designed-pilotevaluation........................................................96
CONCLUSIONS...........................................................................................100

LISTOFPUBLICATIONS.............................................................................102
REFERENCES..............................................................................................103
APPENDIX


LISTOFABBREVIATIONS ANDSYMBOLS
1. Abbreviations
AOPs

:

Advancedoxidationprocesses

BET

:

Brunauer–Emmett –Teller

BQ

:

p-Benzoquinone

CB

:

Conductionband


COD

:

Chemicaloxygendemand

CVD

:

Chemicalvapourdeposition

DMSO

:

Dimethylsulfoxide

DRS

:

Diffusereflectancespectroscopy

EDX

:

Energy-dispersiveX-rayspectroscopy


ENR

:

Enrofloxacin

FTIR

:

Fouriertransforminfrared

IR

:

Infrared

LC-MS

:

Liquid chromatography – Mass

spectrometryLED :

Light-emittingdiode

LP


:

Standardizedlamppower

MB

:

Methyleneblue

MCN

:

MoS2/g-C3N4

MS2

:

MoS2,WS2

PL

:

Photoluminesence

PSTY


:

Photochemicalspace-timeyield

pzc

:

Pointofzerocharge

RhB

:

RhodamineB

SEM

:

Scanningelectronmicroscopy


SSA

:

Specificsurfacearea


STY

:

Space-timeyield

TBA

:

Tert-butylalcohol

TEM

:

Transmissionelectronmicroscopy

TEOA

:

Triethanolamine

TGA

:

Thermalgravimetricanalysis


TMDs

:

Transitionmetalchalcogenides

UV

:

Ultraviolet

WCN

:

WS2/g-C3N4

VB

:

Valenceband

XPS

:

X-rayphotoelectronspectroscopy


XRD

:

X-raydiffraction

C

:

Concentration

D

:

Innerdiameter

Eg

:

Bandgap

h

:

Planckconstant


k

:

Rateconstant

m

:

Mass

P

:

Power

Q

:

Flowrate

q

:

Adsorptioncapacity


Re

:

Reynoldnumber

2. Symbols


r

:

reactionrate

S

:

Surface area

t

:

Time

V

:


Volume

ρ

:

Densityofflowing fluid

π

:

Pinumber

μ

:

Dynamicviscosity

ν

:

Frequency

θ

:


Fractionofreactantabsorbed


LISTOFTABLES
Table2.1.Mainfeaturesoftheusedchemicals......................................................28
Table2.2.Equipmentforpilotbuilding............................................................29
Table3.1.BETspecificsurfacearea(SSA)andporevolumeofthegC3N4,MoS2andMCNxsamples....................................................................63
Table3.2.PSTYdataforthechosenreactionsystems.........................................83


LISTOFFIGURES
Figure 1.1.MoS2structure in three dimensions with the distance between
thetwoadjacentlayers of6.5 Å[142]....................................................................8
Figure1.2.Fourcommon MoS2poly-types[12]...................................................9
Figure1.3.Photocatalysisprinciple[17].............................................................14
Figure1.4.Five-stepflowchartofheterogeneous photocatalysis[17]15
Figure1.5.Molecularstructureofenrofloxacin(left)anditsUV-Visspectrum(right).. .22
Figure 1.6.Methylene blue (a) and rhodamine B (b) structures and
theircorrespondingUV-Vis spectra............................................................23
Figure2.1.Formationofg-C3N4fromthioureabyheating.....................................30
Figure2.2.Imagesofsamplesg-C3N4,WS2,5WCN,7WCN

and10WCN.31Figure

2.3.Images of samples g-C3N4, MoS2, MCN1, MCN2, MCN3 andMCN5.......33
Figure2.4.Photocatalyticreactor.............................................................36
Figure 2.5.Reaction system: (a) black box, (b) DC power supply and
(c)thermostatbath.
..................................................................................................................

36
Figure2.6.Spectrumoflightemittedfromtheincandescentlamp........................37
Figure2.7.SpectrumoftheblueLEDlight.......................................................38
Figure
2.8.Calibrationcurvesforquantitativedeterminationoftargetmolecules......39
Figure2.9.Photocatalyticpilot..........................................................................42
Figure2.10.Schematicrepresentationofthepilot:dischargingvalve(1),chargingv
alvewithfilter(2),controlbox(3),stirrer(4),pumpingvalve(5),
flowsensor(6),deliverytube(7),blueLEDs(8),rechargingtube(9),pump
(10)andsettlingcolumn(11)..............................................................................43


Figure2.11.Controlbox....................................................................................44
Figure2.12.Feed tank.......................................................................................45
Figure2.13.Collector: (a)not working,(b)working............................................45
Figure2.14.Timingprogram..............................................................................46
Figure3.1.XRDpatternsof5WCN,7WCN,10WCN,WS 2,gC 3N4,andthereferencefor WS2(Rf).......................................................................50
Figure3.2.SEMimagesof5WCN(a),7WCN(b),10WCN(c),WS 2(d),andgC3N4(e).............................................................................................................51
Figure3.3.EDXelementalmappingofC(a),N(b),S(c)andW(d)elementsfor10WC
N......................................................................................................................52
Figure3.4.TEM imagesof10WCN(a)andg-C3N4(b)..........................................53
Figure3.5. I R sp ec t r a of 5 WC N, 7W CN , 1 0 W C N , W S 2,an d g .....................................................
C 3N4i n t he wavenumberregionof400-4000cm-1
53
Figure3.6.IRspectraof5WCN,7WCN,10WCN,WS 2inthewavenumber
.........................................................................................
regionof400– 600cm-1
54
Figure3.7.Raman spectrumof 10WCN............................................................55
Figure3.8.High-resolutionXPSofC1s(a),N1s(b),S2p(c),W4d(d),W4f(e)andXPSof

10WCN(f)........................................................................................................56
Figure3.9.TGAcurvesofsamples5WCN,7WCN,10WCN,WS2andg-C3N4.
.........................................................................................................................58
Figure3.10.UVVisdiffusereflectance spectraof5WCN, 7WCN,10WCN composites,WS2,a
ndg-C3N4..........................................................................................................59
Figure3.11.XRDpatternsofMoS2,g-C3N4,andMCNx(x=1,2,3,5).60
Figure3.12.F T I R s p e c t r a o f M o S 2,g - C 3N4a n d M C N x ( x = 1 , 2 , 3 , 5 )
samples............................................................................................................61
Figure3 . 1 3 . X P S s p e c t r a o f M o 3 d ( a ) , S 2 p ( b ) a n d ( c ) X P S s u r
v e y spectrumof MCN5sample.
..................................................................................................................
62


Figure3.14.N2adsorptionisothermsofMoS2,g-C3N4andMCNx(x=1,2,3,5)samples
.........................................................................................................................63
Figure3.15.TGAcurvesofsamplesMoS2,g-C3N4,andMCNx(x=1,2,3,5)

in

Ar

atmosphere......................................................................................................64
Figure 3.16.UV-Vis absorption spectra (a) and corresponding Tauc plots
(b)of MoS2,g-C3N4,andMCNx(x =1,2,3,5)......................................................65
Figure 3.17.EDX elemental mapping of C (a), N (b), Mo (c) and S
(d)elementsfor MCN2sample....................................................................66
Figure

3.18.Adsorption-desorption


equilibrium

of

MB

over

WS 2,

5WCN,7WCN, 10WCN and g-C3N4in the dark. Conditions: initial MB
.......................................
concentration30mg.L-1,pH6.4, catalystloading1.1g.L-1
67
Figure 3.19.Adsorption-desorption equilibrium of RhB over MCN5,
MCN3,MCN2, MCN1 and g-C3N4in the dark. Conditions: initial RhB
.......................................
concentration5 mg.L-1,pH3, catalystloading0.7g.L-1
68
Figure3.20.AdsorptiondesorptionequilibriumofRhBoverMoS2inthedark.Conditions:initialMBconcentration25
mg.L-1,pH3,catalystloading0.7g.L-1....................................................................68
Figure 3.21.Photocatalytic degradation of MB on 5WCN, 7WCN,
10WCN,WS2andgC3N4,andwithoutthephotocatalyst.Conditionsofprocess:irradiated volume:
90

mL,

initial


MB

concentration:

mg.L -

30.0

1

,pH6.4,catalystloading:1.1g.L -1,25oC,under100Wincandescentlamp.

.........................................................................................................................69
Figure 3.22.First-order kinetic plots for the photodegradation of MB
over5WCN,7WCN,10WCN, WS2andg-C3N4underspecified conditions7 0
Figure3.23.First-orderkineticplotsforthephotodegradationofRhBoverMCNx
and g-C3N4samples.

Conditions

of

process:

irradiated

25mL,initialRhBconcentration:5.0mg.L-1,pH3.0,catalystloading:0.7g.L-

volume:



1

, 25oC,underbluelight.ExceptforMoS2: initialRhBconcentration:25.0mg.L-1
..................................................................................................................
71
Figure3.24.PLspectraofg-C3N4andMCN1sample........................................72
Figure3 . 2 5 . E f f e c t o f c a t a l y s t l o a d i n g o n ( a ) R h B d e g r a d a t i o n o v e r M
C N 1 catalystintheconditions:irradiatedvolume:25mL,initialRhBconcentration:
5.0 ppm, pH: 3.0, 25oC, under blue light, and (b) MB degradation over
7WCNcatalystintheconditions:irradiatedvolume:90mL,i n i t i a l M B concentra
tion:3 0 . 0 m g . L -1,p H 6 . 4 , 2 5 oC,u n d e r 1 0 0 W i n c a n d e s c e n t l a m p .
.........................................................................................................................73
Figure3 . 2 6 . I r r a d i a n c e o f t r a n s m i t t e d b l u e l i g h t o f d i f f e r e n t R
h B s o l u t i o n heightswithvaryingloadingsofMCN1fromthesolution.................74
Figure3.27.ValuesofpHpzcof(a)MCN1and(b)7WCNsamples..........................75
Figure3.28.RhBmoleculeexistsas(a)cationicformand(b)zwitterionicform.
.........................................................................................................................75
Figure3.29.Thesolelyexisted cationicformof MB.............................................76
Figure3.30.EffectofinitialpHonRhBdegradationoverMCN1photocatalyst.Process
conditions:initialconcentration,5.0ppm;catalystloading:0.7g.L-1;25oC;underbluelight........................76
Figure3.31.EffectofinitialpHonRhBdegradationover7WCNphotocatalyst.Process
conditions:initialconcentration,30.0ppm;catalystloading:1.1g.L-1;25oC;under100 Wincandescentlamp
.........................................................................................................................77
Figure3.32.AdsorptioncapacityofMCN1(a)and7WCN(b)materialstowardRhBatdiff
erentsolutionpHs..............................................................................................78
Figure3.33.(a)EffectofinitialpHonMBdegradationoverMCN1photocatalyst.
Process conditions: initial concentration, 10.0 ppm; catalystloading: 0.7 g.L-1;
25oC;


under

blue

light,

and

(b)

Effect

of

initial

pH

MBdegradationover7WCNphotocatalyst.Process conditions: initial

on


concentration,30.0ppm;catalystloading:1.1g.L1

;25oC;under100Wincandescentlamp.....................................................................79

Figure 3.34.Adsorption capacity of 7WCN and MCN1 materials towards
MBatdifferentsolutionpHs.....................................................................................80
Figure 3.35.First-order kinetic plots for the photodegradation of: (a)

MBover MCN1 material. Conditions of process: irradiated volume: 25
mL,initial MB concentration: 10.0 mg.L -1, pH 10.0, catalyst loading: 0.7
g.L1

,25oC,underbluelight,and(b)MBandRhBover7WCNmaterial.Conditionsof

process:irradiatedvolume:90mL,initialdyeconcentration:
30.0 mg.L-1, pH 2.5 for RhB and 9 for MB , catalyst loading: 0.7 g.L -1,
25oC,under 100Wincandescentlamp..........................................................81
Figure

3.36.Effect

of

H2O2-RhB

molar

ratio,

abbreviated

as

Rnumber.Process conditions: catalyst loading: 0.7 g.L -1, initial RhB
concentration:5.0 ppm,pH: 3.0, 25oC, under blue light............................85
Figure 3.37.Photodegradation of RhB over MCN1 catalyst in the presence
ofdifferent trapping agents TEOA, BQ, TBA, and DMSO as hole,
superoxideradicalanion,hydroxyl radical,electron scavengers,respectively.....86

Figure

3.38.a)

Proposed

photocatalytic

mechanism

over

MoS2/g-

C3N4undervisible light and b) proposed model for relationship between
adsorption andphotocatalysis..........................................................................88
Figure3.39.TimedependentadsorptionspectraofRhBsolution.Conditionso f pr o ce ss : irradi at ed
vol um e: 2 5 mL, i n i t i al RhB c on ce nt r a t i on :
5.0mg.L-1,pH3.0,MCN1catalystloading:0.7g.L-1,25oC,underbluelight.
.........................................................................................................................90
Figure3.40.TransformationofrhodamineBtorhodamine110.............................91
Figure 3.41. Photodegradation of 20 mL ENR of 5 ppm, catalyst
loading:0.5g.L-1,under bluelight(0.2A,3.0V) for2h,25oC atdifferentpHs.91