Pl-g-C3N4 Z体系 氧化NO消除

Removal of Nitric Oxide through Visible Light Photocatalysis by

g?C3N4Modi?ed with Perylene Imides

Guohui Dong,*,?,∥Liping Yang,?,?,∥Fu Wang,?Ling Zang,*,§and Chuanyi Wang*,?

?Laboratory of Environmental Sciences and Technology,Xinjiang Technical Institute of Physics&Chemistry,Key Laboratory of Functional Materials and Devices for Special Environments,Chinese Academy of Sciences,Urumqi830011,People’s Republic of China

?The Graduate School of Chinese Academy of Science,Beijing100049,People’s Republic of China

§Nano Institute of Utah and Department of Materials Science and Engineering,University of Utah,Salt Lake City,Utah84112, United States

*Supporting Information

light on the design of visible photocatalysts with tunable

sustainability.

oxygen activation

INTRODUCTION

As a common gaseous pollutant,nitric oxide(NO)causes environmental problems,such as haze,photochemical smog, acid rain,and ozone depletion.1?3The concentration of NO in the atmosphere has greatly increased over the past decades because of the increasing numbers of automobiles and amount of industrial activities.4,5Therefore,developing e?cient and economical technologies to eliminate atmospheric NO has become a global concern.Although some methods,including thermal catalysis reduction and physical or chemical adsorption, have been adopted to remove NO from the atmosphere,most of them su?er from low e?ciency and may produce secondary pollution.6?9As an e?cient catalytic process that can be operated under mild conditions(e.g.,without high temperature or addition of strong oxidizing or reducing reagents), semiconductor photocatalysis has recently been recognized as an attractive alternative technology for NO removal.10Under ambient light irradiation(with energy equal to or higher than the bandgap of the semiconductor),an electron(e?)is excited from the valence band(VB)into the conduction band(CB), leaving a hole(h+)in the valence band.The photogenerated electrons and holes migrate to the photocatalyst surface and initiate subsequent redox reactions.11Through the redox reactions,NO can be eliminated e?ectively.Utilization of solar energy to treat environment problems,such as those via photocatalysis,has been considered to be the most energy-e?cient and cost-e?ective approach.

It was reported that metal oxide semiconductors such as TiO2,SiO2,and Al2O3could function as e?ective photocatalysts for complete removal of NO under UV light irradiation.12?14 However,the wide band gap of these materials limits the photoresponse to the UV region,with no use of visible light, which accounts for about5times higher intensity in comparison to UV light in the solar spectrum.Therefore,it is desirable to develop visible light sensitive photocatalysts for their practical application in NO removal.In this regard,many visible light photocatalysts,such as BiOBr,InVO4,Bi2MoO6, (BiO)2CO3,and graphitic carbon nitride(g-C3N4),have been developed and utilized for NO removal.15?20Among these catalysts,g-C3N4is a metal-free polymeric semiconductor material,which has become increasingly promising for photocatalysis under visible light mainly due to its desirable band gap of2.7eV,strong robustness,and low cost.21?23Our previous work demonstrated that g-C3N4could oxidize NO to Received:June12,2016

Revised:August2,2016

Published:August24,2016

NO 2under

visible light irradiation.24

However,NO 2is a more toxic gas,which is detrimental to the lungs and increases the

risk of bronchitis and pulmonary ?brosis.Recently,we found that modi ?cation of g-C 3N 4with noble metals could change the

?25

method which causes g-C N to deeply oxidize NO to NO ?

state Z-scheme heterojunction structured photocatalyst on g-C 3N 4,with which the photogenerated electrons and holes can be separated into two di ?erent phases,helping spatially isolate the oxidation and reduction reaction sites 26and thus minimizing the catalytic deactivation.Molecules of perylene tetracarboxylic diimide (PTCDI)represent a unique class of n-type organic semiconductor,with strong thermal and light stability.27PTCDI materials have been extensively used in bulk heterojunction (BHJ)solar cells because of their strong visible light absorption,good charge transportation properties,and durable photostability.27?29PTCDI can be synthesized through a one-step reaction between perylene tetracarboxylic dianhydride (PTCDA)and a primary amine (?NH 2).Since the edges of g-C

3N 4are full of ?NH 2groups,PTCDI can be modi ?ed onto g-C 3N 4simply by

reacting PTCDA with g-C 3N 4in solution.In this study,we provide an all-solid-state Z-scheme heterojunction consisting of PI and g-C 3N 4(PI-g -C 3N 4)for the photocatalytic removal of NO under visible light.The structure of the PI-g -C 3N 4heterojunction was characterized by various experimental methods.In comparison to the single-phase g-C 3N 4,PI-g -

C 3N 4demonstrated much improved photocatalytic e ?ciency

for NO removal.The photocatalysis mechanism of the heterojunction structure was deeply explored,as presented below.■EXPERIMENTAL SECTION

Preparation of Photocatalysts.All chemicals were purchased in analytical grade and used without further

puri ?cation.g-C 3N 4was synthesized by direct heating of melamine following a protocol developed in our previous work.30Typically,a given amount of melamine was placed in a covered

crucible and heated to 520°C

at a heating rate of 20°C/min and kept at 520°C for 4h.In order to modify the surface of g-C 3N 4with PTCDI,PTCDA was chosen to react with g-C 3N 4via the condensation

reaction illustrated in Scheme 1.Brie ?y,PTCDA (0.0355g),g-C 3N 4(0.71g),and imidazole (2.5g)were placed in a 100mL three-neck round-bottom ?ask,followed by heating at 140°C for 5h under a nitrogen atmosphere.Then the reaction mixture was cooled to room temperature and 50mL of ethanol was placed in the reaction vessel with stirring.The solution was

then transferred to a 250mL ?ask containing 150mL of 2M hydrochloric acid (HCl).After it was stirred for 12h,the mixture was centrifuged and washed thoroughly with methanol and deionized water.The resulting red solid was transferred to a 100mL round-bottom ?ask containing 50mL of potassium carbonate aqueous solution (K 2CO

3,10%),which was re ?uxed in an oil bath at 100°C for 1h.After it was cooled to 50°C,the solution was centrifuged and washed three times with 300mL of K 2CO 3solution (10%)and then with 50mL of 2M HCl (2mol/L).The sample obtained was ?nally washed thoroughly with methanol and deionized water until the pH of the rinsed water became neutral.The collected solids (PI-g -C 3N 4)were dried under vacuum at 80°C for 12h.Sample Characterization.UV ?vis absorption spectra of g-C 3N 4and PI-g -C 3N 4were recorded on a Solid Spec-3700

DUV spectrophotometer using BaSO 4as reference and were converted from re ?ection to absorption by the Kubelka ?Munk method.The powder X-ray di ?raction (XRD)measurements were recorded on a Bruker D8di ?ractometer with mono-chromated Cu K αradiation (λ=1.5418?).Fluorescence spectra were monitored with a ?uorescence spectrophotometer (Hitachi,Model F-7000)equipped with a PC recorder.Electron paramagnetic resonance (EPR)spectra were recorded on a Bruker ElexsysE500spectrometer by applying an X-band (9.43GHz,1.5mW)microwave with sweeping magnetic ?eld at 110K in cells that can be connected to a conventional high-

Scheme 1.Synthetic Route of PI-g -C 3N 4

vacuum apparatus (residual pressure <10?4mbar).Surface electronic states were analyzed by an X-ray photoelectron spectrometer (XPS,ESCALAB MK II).All binding energies were calibrated by using the contaminant carbon (C(1s)=284.6eV)as a reference.Transmission electron microscopy (TEM)imaging was performed on a JEOL JSM-2010microscope.For TEM measurements,the samples were suspended in ethanol,and then a drop of this suspension was deposited onto a carbon ?lm supported by a copper grid.Photocatalytic NO Removal Test.Photocatalytic removal of NO was tested over g-C 3N 4,PI-g -C 3N 4,or PTCDA under visible or UV light irradiation.The experiments were performed at ambient temperature in a continuous-?ow reactor with a starting concentration of NO at 600ppb levels.A cylindrical reactor with a volume of 0.785L (πR 2H (π×52cm 2×10cm))was made of Pyrex glass with a top window made of quartz.A glass dish (R =3cm)deposited with a given amount of g-C 3N 4,PI-g -C 3N 4,or PTCDA was placed in the middle of the reactor.A 300W Xe lamp with a 420nm cuto ??lter was vertically placed above the quartz window,so that the incident light can irradiate directly on the sample dish.The glass dish samples were prepared by coating an aqueous suspension of g-C 3N 4,PI-g -C 3N 4,or PTCDA onto the dish.Typically,50mg of g-C 3N 4,PI-g -C 3N 4,or PTCDA was added to 10mL of H 2O and ultrasonicated for 15min.The aqueous suspension was then cast onto the glass dish,followed by drying at 60°C until the water was completely removed.During photocatalytic removal tests,the NO concentration was diluted to about 600ppb by air stream.The ?ow rate was controlled at 1L/min by a mass ?ow controller.The change in NO concentration was continuously measured by using a chemiluminescence NO analyzer (Thermo Scienti ?c,42i).NO removal e ?ciency (η)was calculated as follows:η=?×C C (%)(1/)1000where C and C 0are the concentrations of NO in the outlet stream and feeding stream,respectively.Scavenging Experiments.In general,photocatalytic reactions involve various active species,such as the photo-generated electron (e ?),hole (h +),superoxide (?O 2?),and hydrogen peroxide (H 2O 2).Comparative investigations of the e ?ect of these species on the photocatalysis were performed by using scavenger agents to remove the di ?erent species.Potassium iodide (KI),potassium dichromate (K 2Cr 2O 7),and tert -butyl alcohol (TBA)were employed as scavengers for h +,e ?and ?OH,respectively.Typically,50mg of photocatalyst was mixed with 1mM of the di ?erent trapping agents in 10mL of H 2O and ultrasonicated for 15min.Then,the aqueous suspensions were coated onto the glass dish followed by drying at 60°C until the water was completely removed.The coated dishes were used in the photocatalytic NO removal experiments as described above.Detection of H

2O 2.The concentration of H

2O 2was determined by utilizing a ?uorescence reagent,as reported in our previous work.31Typically,the ?uorescence reagent was prepared by mixing (p -hydroxyphenyl)acetic acid (POHPAA,

2.7mg)and horseradish peroxidase (1mg)in potassium hydrogen phthalate bu ?er solution (10mL,8.2g/L,pH 4.01)with stirring.Photocatalytic reactions (H

2O 2generation reactions)were conducted with a 50mL suspension containing 50mg of the respective catalyst under visible irradiation under

atmosphere (1atm)at 20°C.In the process of the reaction,continuous stirring was applied to keep the photocatalysts well

suspended.About 2mL of the reaction mixture was taken from the reaction cell at given time intervals and centrifuged to remove the photocatalysts.The clear solution thus obtained was added 50μL of the ?uorescence reagent.After 10min of reaction,1mL of 0.1M NaOH solution was added for the subsequent ?uorescence measurements.The reaction product

between

H 2

O 2and the ?uorescence reagent has a strong ?uorescent emission at 409nm on excitation at 315nm.

Photoelectrochemical Experiments.The photoelectro-des were prepared according to our previously reported

method.32Photocatalysts were dispersed in α-naphthol (0.5wt %)solution and ground for 10min.The resultant slurry was then blade coated on a 1×1cm 2

?uorine tin oxide (FTO)glass substrate with a glass slide,using adhesive tapes as spaces.Then the ?lm was dried in air and annealed at 150°C for 15min.Photoelectrochemical experiments were performed in a conventional three-electrode cell with a platinum plate (1×

1cm 2)as the counter electrode and a saturated calomel

electrode (SCE)as the reference electrode on an electro-

chemical workstation (CHI660C,Chenhua,People ’s Republic

of China).The prepared working electrode was positioned in

the middle of a 0.1M KCl aqueous solution with the glass side facing the incident light.A 200W Xe lamp with a 420nm cuto

??lter was chosen as the visible light source.■RESULTS AND DISCUSSION After the synthesis of g-C 3N 4and PI-g -C 3N 4,we found that the

modi ?cation with PTCDI changes the color of g-C 3N 4from

light yellow to pink (Figure 1a),implying increased absorption in visible light.The structure of PI-g -C 3N 4was characterized by X-ray di ?raction (XRD)in comparison with pure g-C 3N 4

and

Figure 1.(a)Photographs of g-C 3N 4(yellow)and PI-g -C 3N 4(pink)solid showing the di ?erent colors.(b)XRD patterns of PI-g -C 3N 4,g-C 3N 4,and

PTCDA.(c)Small-angle XRD patterns of PI-g -C 3N 4,g-C 3N 4,and PTCDA.

PTCDA powders.The XRD spectra (Figure 1b,c)showed only the phase of g-C 3N 4,whereas no di ?raction of the PTCDI phase was observed,indicating that the PTCDI molecules are sparsely distributed on the surface of g-C 3N 4rather than existing as solid π?πstacks.This is consistent with the low density of ?NH 2groups distributed along the edge of g-C 3N 4.The overall platelet-like morphology of g-C 3N 4remained about the same after the surface modi ?cation of PTCDI,as evidenced by the transmission electron microscopy (TEM)imaging (Figure 2a,b).XPS was further employed to investigate the surface chemical composition and chemical states of the g-C 3N 4and PI-g -C 3N 4samples (Figure 3),wherein only carbon,nitrogen,and oxygen species were detected (Figure 3a).Both of the samples show an O 1s peak at 532.2eV,which is likely due to the surface-adsorbed H 2O or hydroxyl group.In comparison,the PI-g -C 3N 4samples show a new O 1s peak at 531.1eV (Figure 3b),which can be ?tted with C ?O and carbonyl groups,indicating

the formation of imide groups of PTCDI.The high-resolution N 1s spectrum of g-C 3N 4is shown in Figure 3c.The observed

peak can be deconvoluted into two peaks which are ascribed to the nitrogen in C ?N ?C (398.4eV)and C ?N

3(400.7eV)

groups,respectively.These two nitrogen peaks are also obtained for PI-g -C 3N 4sample,indicating that the main

skeleton of g-C 3N 4remained unchanged after modi ?cation of PTCDI.Interestingly,an additional N 1s peak at 399.8eV was observed for PI-g -C 3N 4,which can be attributed to the imide nitrogen within the PTCDI part.Modi ?cation of PTCDI extended the absorption of g-C 3N 4in the visible region,as evidenced by the emerging absorption bands around 500and 550nm (Figure 4a),which are characteristic of PTCDI in the solid state.27Moreover,the UV ?vis absorption edges of PI-g -C

3N 4show a red shift in

comparison with that of g-C 3N 4.This phenomenon suggests

that the intermolecular interaction occurs between PTCDI and g-C 3N 4.PTCDA material is not ?uorescent due to the strong π?πstacking,which limits the low-energy excitonic transition.PTCDI becomes ?uorescent when the side groups help

tune

Figure 2.TEM images of g-C 3N 4(a)and PI-g -C 3N 4

(b).

Figure 3.(a)XPS spectra of g-C 3N 4and PI-g -C 3N 4.(b,c)High-resolution XPS spectra of O 1s (b)and N 1s (c)of g-C 3N 4and PI-g -C 3N 4

.Figure 4.(a)UV ?vis absorption spectra of g-C 3N 4,PI-g -C 3N 4,and PTCDA.(b)Photoluminescence (PL)spectra of g-C 3N 4,PI-g -C 3N 4,and PTCDA

(excited at 500nm).

the π?πstacking.27

As shown in Figure 4b,signi ?cant ?uorescence (peak at 571nm)was observed for PI-g -C 3N 4on excitation at 500nm,indicating the existence of PTCDI,whereas the same ?uorescence peak was not measured for g-C 3N 4or PTCDA.These observations further con ?rm the surface modi ?cation of g-C 3N 4by PTCDI,consistent with the XPS results above.The as-prepared PI-g -C 3N 4was employed for photocatalytic removal of NO under visible light irradiation (λ>420nm)to investigate the e ?ect of the heterojunction between PTCDI and g-C 3N 4on the catalysis e ?ciency.Figure 5a shows the relative change of NO concentration (C /C 0)as a function of irradiation time tested over the three di ?erent catalysts PI-g -C 3N 4,g-C 3N 4,and PTCDA.As a control test,the removal of NO was negligible under the same visible light irradiation for 50min,indicating the high photostability of NO to visible light.As shown in Figure 5a,37%of the NO was removed over pure g-C 3N 4after 35min of irradiation,while 47%was removed in only 10min when PI-g -C 3N 4was used as a catalyst under the same irradiation,indicating much improved catalysis e ?ciency.(We selected an optimal relative content ratio of PI to g-C 3N 4in the present work.The photoactivities for NO removal of samples at other ratios can be found in Figure S1in the Supporting Information.)In contrast,PTCDA did not demonstrate any catalysis for NO removal under the same

photoirradiation.In addition to the decrease in NO concentration,the concentration of NO 2produced during the photocatalysis was also monitored (Figure 5c).With g-C 3N 4as the catalyst the

amount of NO 2produced increased gradually and reached a plateau value after about 40min of irradiation,clearly indicating that the main product of the photocatalysis is NO 2.In sharp comparison,when PI-g -C 3N 4was used as catalyst instead,the generation of NO 2quickly reached its equilibrium (within ca.5min)and the accumulated amount of NO 2was 1order of magnitude lower than that in the case of g-C 3N 4.This implies that most of NO 2was further converted (oxidized)to NO 3?.Such conversion was con ?rmed by FTIR spectral measure-ments.The PI-g -C 3N 4sample after photocatalytic tests was collected and analyzed by FTIR.It can be seen that the used PI-g -C 3N 4exhibits new bands at 1457and 1419cm ?1(Figure 5d),which are ascribed to the antisymmetric stretching vibration modes of NO 3?groups,implying that the major product in PI-g -C 3N 4is NO 3?.It was reported that NO

3?can occupy the surface active sites,causing the deactivation of g-C 3N 4.17,25

Therefore,the stability and recyclability of PI-g -C 3N 4were examined and compared with those of g-C 3N 4and Pd-g -C 3N 4

(g-C 3N 4

was modi ?ed by the nanopalladium.The main

product Figure 5.(a)Relative change in NO concentration (C /C 0)as a function of irradiation time tested over g-C 3N 4,PI-g -C 3N 4,and PTCDA.(b)NO 2

concentration changing with irradiation time tested over g-C 3N 4and PI-g -C 3N 4.(c)FTIR spectra of PI-g -C 3N 4before and after use in the photocatalytic removal of NO.In all of the experiments,the initial concentration of NO was 600ppb,the amount of g-C 3N 4,PI-g -C 3N 4,and

PTCDA used was 50mg,and a 300W Xe lamp with a 420nm cuto ??lter was used as the visible light

source.Figure 6.Repeated testing of the photocatalytic NO removal over PI-g -C 3N 4(a),g-C 3N 4(c),and Pd-g -C 3N 4(e)and NO 2concentration changes on

repeated testing over PI-g -C 3N 4(b),g-C 3N 4(d),and Pd-g -C 3N 4(f).

of NO removal over it is NO 3?.25The synthetic process can be found in the Supporting Information .)by running the same photocatalytic removal experiment continuously in multiple cycles.The results evince that the activity of PI-g -C 3N 4does not decline after eight cycles of NO removal under the visible light irradiation (Figure 6a).However,the NO removal on g-C 3N 4and Pd-g -C 3N 4decreased about 10%and 67%,

respectively (Figure 6c,e).The activity decrease of g-C 3N 4and Pd-g -C 3N 4should be attributed to the occupation of active sites caused by the NO 3?.Although the activity of g-C 3N 4did not signi ?cantly decline,it could produce a large amount of NO 2in each cycle of photocatalytic NO removal (Figure 6d).In comparison with g-C 3N 4and Pd-g -C 3N 4,PI-g -C 3N 4can not only greatly alleviate the deactivation of NO removal but also e ?ectively inhibit the second pollution due to the production of NO 2.The catalytic activity of PI-g -C 3N 4remained about the same after eight cycles of test,indicating that the formation of NO 3?may occur at a position segregated from the catalyst.Generally,the photocatalytic removal of NO involves the surface reactions of both photogenerated holes and electrons,which may also produce oxidizing species,such as ?O 2?,H 2O 2and ?OH to further the oxidation reactions.10,33In this study,a DMPO spin-trapping ESR technique was employed to characterize the ?O 2?species generated during photocatalysis.As shown in Figure 7a,four characteristic peaks of DMPO-?O 2?were clearly observed in methanol suspensions of g-C 3N 4,whereas only a trace level

of DMPO-?O 2?could be detected for

the PI-g -C 3N 4under the same conditions.However,the PI-g -C 3N 4system produced about 5times more H 2O 2than the g-

C 3N 4system (Figure 7b).Since in semiconductor photo-catalysis H 2O 2is normally generated through direct reduction (O 2→H 2O 2)or a multistep reaction (O 2→?O 2?→H 2O 2)

from oxygen,31the ESR results suggest that H 2O 2is likely produced via direct reduction in the PI-g -C 3N 4suspension,in comparison to the multistep reaction route in g-C 3N 4.The photocatalytic reactions of NO removal over g-C 3N

4and PI-g -C 3N 4were further

explored through a series of control experiments.With addition of potassium iodide (KI,a hole scavenger 34)the NO removal was signi ?cantly depressed for both g-C 3N 4and PI-g -C 3N 4(Figure 8a,b),suggesting that

the

Figure 7.(a)DMPO

spin-trapping ESR spectra recorded for ?

O 2?in the g-C 3N 4and PI-g -C 3N 4systems (under λ>420nm irradiation),where the

concentration of DMPO was 25mmol L ?1.(b)Comparison of H 2O 2generation in the g-C 3N 4and PI-g -C 3N 4systems under the same photocatalytic

conditions.Figure 8.In ?uence of di ?erent scavengers (KI for h +,K 2Cr 2O 7for e ?,TBA for ?OH,PBQ for ?O 2?,CAT for H 2O 2)on the photocatalytic removal of NO using g-C 3N 4and PI-g -C 3N 4.The photocatalysis conditions are the same as in Figure 5.

photogenerated holes paly a critical role in NO removal in both cases.On the other hand,when potassium dichromate (K 2Cr 2O 7,an electron scavenger 35)was added,the NO removal was inhibited over g-C 3N 4(Figure 8a),whereas the NO removal over PI-g -C 3N 4remained little changed.These observations imply that photogenerated electrons are indis-pensable for NO removal over g-C 3N 4but not PI-g -C 3N 4.Moreover,the production of NO 2during photocatalysis of PI-g -C 3N 4was signi ?cantly increased in the presence of K 2Cr 2O 7(Figure 8d),indicating that the photogenerated holes (increased due to scavenging of electrons)are primarily responsible for oxidizing NO to NO 2in the PI-g -C 3N 4system.Considering the fact that conduction band electrons can be captured by O 2to produce active oxygen species,it is essential to explore the role of these species in conversion of https://www.sodocs.net/doc/2115763849.html,parative investigations were performed by using varying scavengers such as tert -butyl alcohol (TBA)for ?OH,36p -benzoquinone (PBQ)for ?O 2?37and catalase (CAT)for H 2O 238in the photocatalysis.As shown in Figure 8a,b,the addition of TBA did not change the NO removal rate over either g-C 3N 4or PI-g -C 3N 4,suggesting no signi ?cant contribution from ?OH to the photocatalytic removal of NO.Addition of PBQ clearly depressed the NO removal on g-C 3N 4(Figure 8a),but not PI-g -C 3N 4(Figure 8b),implying

di ?erent roles of ?O 2?in the two systems.Also clearly seen from Figure 8is that the addition of CAT did not a ?ect the NO removal rate over either g-C 3N 4or PI-g -C 3N 4.On the other hand,the presence of CAT dramatically increased the NO 2concentration in the PI-g -C 3N 4system (Figure 8d)but brought little e ?ect on

NO 2generation over g-C 3N 4(Figure 8c).These results indicate that H 2O 2facilitates the further conversion (oxidation)of NO 2

to NO 3?in the PI-g -C 3N 4system.On the basis of these comparative observations,we conclude that both the photo-generated hole and H 2O 2are indispensable,playing synergic roles,in the NO removal over PI-g -C 3N 4,enabling ultimate conversion to NO 3?ion,whereas for the NO removal over g-C 3N 4the synergic roles are played by the hole and ?O 2?,resulting in conversion of NO to NO 2(consistent with the previous observation on g-C 3N 424).From the comparative investigations above,the photo-catalytic removal of NO over PI-g -C 3N 4may involve eqs 1?4‐‐+→++?g PI C N visible light h e 34(1)++→+++2h NO H O NO 2H 22(2)++→?+e O 2H H O 222(3)+→+?+2NO H O 2NO 2H 2223(4)The e ?ciency of visible light photocatalysis depends on the visible light absorption of the catalyst.As shown in Figure 4a,

PI-g -C

3N 4(in comparison to g-C 3N 4)has increased absorption in the visible region,particularly above 500nm,which is solely due to the absorption by the PTCDI part.This increased visible absorption caused signi ?cant enhancement in photocatalytic

removal of NO,as shown in Figure 5.Such enhancement could be explained in two possible ways:one is localized on the PTCDI part,and the other is a cooperative process involving both g-C

3N 4and PTCDI parts (Scheme 2).For the ?rst case,visible excitation of the PTCDI (band gap 2.5eV,see the caption of Figure 9)produces electrons and holes,which then initiate the surface redox reactions as observed for other semiconductor photocatalysts.However,the e ?ciency of this catalysis is limited by the fast charge recombination process,which is actually evidenced by the strong ?uorescence of PTCDI measured from the PI-g -C

3N 4sample (Figure 4b).Scheme 2.Two Models of Charge Separation Proposed for PI-g -C 3N 4under Visible Irradiation:(a)Conventional Donor ?Acceptor Charge Transfer and (b)Z-Scheme Electron

Transfer

a a

Energy levels (vs NHE)are obtained from the ?at potential (CB)measured in this study and the band gap values reported in the literature (see Figure 9

).Figure 9.Mott ?Schottky plots for g-C

3N 4and PI-g -C 3N 4at frequency of

1k Hz obtained in darkness.Both g-C 3N 4and PI-g -C 3N 4samples

display n-type semiconductor characteristics.The ?at-band potential (equal to CB

band in n-type semiconductor)was measured at ?1.37

eV

vs NHE for pure g-C 3N 4and ?1.32eV vs NHE for the g-C 3N 4part

in PI-g -C 3N 4.With the known band gap of 2.7eV for g-C 3N 4,20the VB potential

of g-C 3N 4can be calculated to be 1.38eV vs NHE in the PI-

g -C 3N 4composite.The second linear region

in the Mott ?Schottky plot of PI-g -C 3N

4

is attributed

to

the CB band of the PTCDI part,

corresponding to a potential of ?0.64eV vs NHE.With the known band gap of 2.5eV for PTCDI,24the VB potential of PTCDI can be

calculated to be 1.86V vs NHE.

PTCDI alone is unlikely to a ?ord the high e ?ciency of visible photocatalysis.Thereby,the cooperative process (Scheme 2)becomes the reasonable interpretation for the observed enhancement in visible photocatalysis.As shown in Scheme 2(the band potentials were acquired from the Mott ?Schottky plots,Figure 9),both the g-C 3N 4and PTCDI parts are excited under visible light (λ>420nm),followed by electron transfer between g-C 3N 4and PTCDI,which can be classi ?ed into two models.The ?rst is the common donor ?acceptor charge separation as illustrated in Scheme 2a,in which electron transfer occurs from the CB of g-C 3N 4to the CB of PTCDI,leaving a hole in the VB of g-C 3N 4.

If the charge migration occurs via this model,the enhancement of photocatalytic NO removal should also be observed under the UV-light illumination (λ<400nm).The absorption coe ?cient of PTCDI in the UV region is about 15times lower than the maximum in the region of 500?550nm (also note that for PTCDI the absorption coe ?cient does not change with di ?erent side substitutions 39).From the UV ?vis absorption spectrum measured for the PI-g -C 3N 4sample in this study (Figure 4a),the absorption of the PTCDI part in the UV region should be 15times lower than the maximum peak in the region of 500?550nm (where g-C 3N 4has no absorption).By carefully examining the absorption data,we can conclude that the absorption of PI-g -C 3N 4in the UV region is truly dominated by the absorption by g-C 3N 4(>99%in absorption coe ?cient).That is to say,under UV irradiation (λ<400nm)only the g-C 3N 4part is excited.After the excitation,photogenerated electrons will transfer from the CB of g-C 3N 4to the CB of PTCDI,producing electrons and holes located at the PTCDI and g-C 3N 4,respectively,the same charge separation as illustrated in Scheme 2a.However,as shown in Figure 10,under UV irradiation the photocatalytic removal of NO on PI-g -C 3N 4was even slower than that on g-C 3N 4.This observation suggests that the common charge separation model shown in Scheme 2a is not likely the case in the visible photocatalysis of PI-g -C 3N 4.The second model is the Z-scheme charge migration (Scheme 2b),for which the visible excitation initiates the electron transfer from the CB of PTCDI to the VB of g-C 3N 4.This results in a di ?erent way of charge separation with an electron located in the CB of g-C 3N 4and a hole in the VB of PTCDI.40The lower level of VB of PTCDI (by 0.48eV in comparison to that of g-C 3N 4)provides stronger oxidizing power for the hole,thus enabling direct oxidation of NO to NO 2(eq 2),which is consistent with the results shown in Figure 5as discussed above.Meanwhile the electron located in the CB of g-C 3N 4possesses higher reducing power (by 0.68eV in comparison to that of PTCDI),thereby enabling direct reduction of O 2to H 2O 2(eq 3),which is also consistent with the results presented in Figures 7and 8.Because the NO 2,H 2O 2,and NO 3?species are

formed at di ?erent sites in the PI-g -C 3N 4system,the deactivation of catalysis caused by the occupation of active sites could be alleviated greatly (Scheme 3).The heterojunction charge separation as illustrated by the Z-scheme reduces the probability of charge recombination that is often encountered in the single-component photocatalyst,

thus producing an increased density of holes and electrons,

which can act as charge carriers when the catalyst material is employed in a circuit.This is evidenced by the results shown in Figure 11,wherein the photocurrent generated over PI-g -C 3N 4

(4.6μA cm ?2)was about 15times higher than that over g-C 3N 4

(0.3μA cm ?2).

■CONCLUSIONS

In summary,an all-solid-state Z-scheme heterojunction (PI-g -C 3N 4)has been successfully constructed.As tested for photocatalytic removal of NO under visible light,signi ?

cant

Figure 10.Photocatalytic removal of NO under UV light irradiation (λ

<400nm).For UV irradiation (λ<400nm),more than 99%of the irradiation will be absorbed by the g-C 3N 4part.

Scheme 3.NO Photocatalytic Mechanism of PI-g -C 3N 4under Visible Light

Irradiation Figure

11.Photocurrent ?time curves of g-C 3N 4and PI-g -C 3N 4

electrodes in 0.1M KCl aqueous solution under visible light irradiation

(λ>420nm).For comparison,the photocurrent ?time curve of PI was also detected under the same conditions.PI was

prepared in the same manner as for PI-g -C 3N 4,but g-C 3N

4was

replaced by melamine.

enhancement in catalytic activity was observed for PI-g-C3N4in comparison to the pristine g-C3N4.The Z-scheme hetero-junction creates charge separation with the electron populated to the higher CB and hole to the lower VB,thus enhancing the redox reaction power of the charge carriers.The strong hole can directly oxidize NO to NO2,while the strong electron can directly reduce O2to H2O2.Since NO2and H2O2can react at di?erent locations(via di?usion),the NO3?ion produced would cause minimal deactivation to the catalyst.This study provides new insight into the design of e?ective photocatalysts that can be operated under visible light,facilitating the

utilization of solar energy.

■ASSOCIATED CONTENT

*Supporting Information

The Supporting Information is available free of charge on the ACS Publications website at DOI:10.1021/acscatal.6b01657.

Details of the preparation of Pd-g-C3N4and the

photoactivities for NO removal of other samples which

have di?erent content ratios of PI to g-C3N4(PDF)■AUTHOR INFORMATION

Corresponding Authors

*G.D.:e-mail,donggh@https://www.sodocs.net/doc/2115763849.html,;tel,+86-0991-*******; fax,+86-0991-*******.

*L.Z.:e-mail,lzang@https://www.sodocs.net/doc/2115763849.html,.

*C.W.:e-mail,cywang@https://www.sodocs.net/doc/2115763849.html,.

Author Contributions

∥These authors contributed equally to this work.

Notes

The authors declare no competing?nancial interest.■ACKNOWLEDGMENTS

Financial support by the National Nature Science Foundation of China(Grant No.21473248),the CAS/SAFEA Interna-tional Partnership Program for Creative Research Teams,the CAS“Western Light”program(2015-XBQN-B-06),and the NSF(CBET1502433)is gratefully appreciated.

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3205 过氧化氢行业企业安全生产风险分级管控体系实施指南

ICS71.010 G00 DB37 山东省地方标准 DB 37/T 3205—2018 过氧化氢行业企业安全生产风险分级管控 体系实施指南 Implementation Guidelines for the Management and Control System of Risk Classification for Production Safety of Hydrogen peroxide 2018-05-17发布2018-06-17实施

前言 本标准按照GB/T 1.1-2009给出的规则起草。 本标准由山东省安全生产监督管理局提出。 本标准由山东安全生产标准化技术委员会归口。 本标准主要起草单位：山东阳煤恒通化工股份有限公司。 本标准主要起草人：焦荣坤、毛义田、逯登哲、王锦弟、路向宾、李钦超、徐勤、刘义强。

引言 本标准是依据国家安全生产法律法规、标准、规范及山东省地方标准《安全生产风险分级管控体系通则》、《化工企业安全生产风险分级管控体系细则》的要求，充分借鉴和吸收国际、国内风险管理相关标准、现代安全管理理念和过氧化氢行业企业的安全生产风险（以下简称风险）管理经验，融合职业健康安全管理体系及安全生产标准化等相关要求，结合山东省过氧化氢行业企业安全生产特点编制而成。 本标准用于规范和指导山东省过氧化氢行业企业开展安全生产风险分级管控工作，达到有效控制风险，杜绝或减少各种事故隐患，预防生产安全事故发生的目的。

过氧化氢行业企业安全生产风险分级管控体系实施指南 1 范围 本标准规定了过氧化氢行业企业安全生产风险分级管控体系建设的基本要求、工作程序和内容、文件管理、分级管控效果和持续改进等内容。 本标准适用于指导山东省内过氧化氢行业企业安全生产风险分级管控体系的建设。 2 规范性引用文件 下列文件对于本文件的应用是必不可少的。凡是注日期的引用文件，仅所注日期的版本适用于本文件。凡是不注日期的引用文件，其最新版本（包括所有的修改单）适用于本文件。 GB 6441 企业职工伤亡事故分类标准 GB 18218 危险化学品重大危险源辨识 GB 30871 化学品生产单位特殊作业安全规范 GB/T 13861 生产过程危险和有害因素分类与代码 DB37/T 2882-2016 安全生产风险分级管控体系通则 DB37/T 2974-2017 化工企业安全生产风险分级管控体系细则 3 术语和定义 DB37/T 2882-2016 界定的术语和定义适用于本文件。 4 基本要求 4.1 成立组织机构 4.1.1 企业应成立由主要负责人任组长、分管负责人任副组长的安全生产风险分级管控领导小组，小组成员应包括安全、设备、工艺、电气、仪表等各职能部门负责人和各类专业技术人员。 4.1.2 企业应根据规模和运行方式建立车间级和班组级安全生产风险分级管控组织。主要职责如下： ——企业主要负责人全面负责安全生产风险分级管控工作； ——分管负责人负责分管范围内的安全生产风险分级管控工作； ——安全管理部门是安全生产风险分级管控的主管部门，负责制定公司安全生产风险分级管控管理制度、体系运行考核制度、作业指导书等并监督执行； ——各科室（车间）负责组织开展本单位的风险点排查、危险源辨识、风险评价和分级管控具体工作； ——各班组负责组织本班组的风险点排查、危险源辨识、风险评价和分级管控具体工作； ——企业员工、承包商及相关人员，应按照工作要求，参与危险源辨识、风险评价和分级管控相关工作。

无机化学实验(氧化还原平衡)

无机化学实验报告 姓名：黄文轩学号20160182310085 实验名称：氧化还原和电化学 一.实验目的 1.理解电极电势与氧化还原反应的关系 2.掌握介质酸碱性，浓度对电极电势及氧化还原反应的影响 3.了解还原性和氧化性的相对性 4.了解原电池的组成及工作原理学习原电池电动势的测量方法。 二.实验原理 1.氧化还原反应的实质是反应物之间发生了电子转移或偏移。氧化剂在反应中得到电子被还原，元素的氧化值减小，还原剂在反应中被氧化，元素的氧化值增大。物质的氧化还原能力的大小可以根据对应的电对的电极电势的大小来判断。电极电势越大，电对中的氧化型的氧化能力越强，电极电势越小，电对中还原型的还原能力越强。 根据电极电势的大小可以判断氧化还原反应的方向。当氧化剂电对的电极电势大于还原剂电对的电极电势时，即E MF=E(氧化剂）--E(还原剂）>0时，反应能正向自发进行。 由电极的能斯特方程式可以看出浓度对氧化还原反应的电极电势的影响，298.15K时 E=E?+0.0592V Z lg c（氧化型）c（还原型）

1.理解电极电势与氧化还原反应的关系 2.掌握介质酸碱性，浓度对电极电势及氧化还原反应的影响 3.了解还原性和氧化性的相对性 4.了解原电池的组成及工作原理学习原电池电动势的测量方法。 二.实验原理 1.氧化还原反应的实质是反应物之间发生了电子转移或偏移。氧化剂在反应中得到电子被还原，元素的氧化值减小，还原剂在反应中被氧化，元素的氧化值增大。物质的氧化还原能力的大小可以根据对应的电对的电极电势的大小来判断。电极电势越大，电对中的氧化型的氧化能力越强，电极电势越小，电对中还原型的还原能力越强。 根据电极电势的大小可以判断氧化还原反应的方向。当氧化剂电对的电极电势大于还原剂电对的电极电势时，即=E(氧化剂）--E(还原剂）>0时，反应能正向自发进行。 由电极的能斯特方程式可以看出浓度对氧化还原反应的电极 电势的影响，298.15K时 E=?+lg（氧化型） （还原型） 溶液的ph也会影响某些电对的电极电势或氧化还原反应的方向。介质的酸碱性也会影响某些氧化还原反应的产物，如MnO4-在酸性，中性，碱性介质中的还原产物分别为Mn2+,MnO2和MnO4(2-).

氧化还原滴定法原理

四、氧化还原滴定法原理 （一）氧化还原滴定指示剂 常用指示剂有以下几种类型： （1）.自身指示剂 有些标准溶液或被滴定物质本身有颜色，而滴定产物无色或颜色很浅，则滴定时就无需另加指示剂，本身颜色变化起着指示剂的作用叫作自身指示剂。 MnO4-（紫红色）+ 5Fe2+ + 8H+ = Mn2+（肉色，近无色）+ 5Fe3+ + H2O KMnO4的浓度约为2×10-6 mol/L 时就可以看到溶液呈粉红色，KMnO4滴定无色或浅色的还原剂溶液，不须外加指示剂。KMnO4称为自身指示剂。 （2）．显色指示剂 有些物质本身并没有氧化还原性，但它能与滴定剂或被测物质产生特殊的颜色，因而可指示滴定颜色。 I2 + SO2 + 2H2O = 2I- + SO42- + 4H+ 可溶性淀粉与碘溶液反应，生成深蓝色的化合物，可用淀粉溶液作指示剂。在室温下，用淀粉可检出10-5mol/L 的碘溶液。温度升高，灵敏度降低。 （3）．本身发生氧化还原反应的指示剂 这类指示剂的氧化态和还原态具有不同的颜色，在滴定过程中，指示剂由氧化态变为还原态，或由还原态变为氧化态，根据颜色的突变来指示终点。 作用原理：设指示剂氧化还原电对为 式中In(O)和In(R)分别代表具有不同颜色的指示剂的氧化态和还原态。随着滴定的进行，溶液电位值发生变化，指示剂的也按能斯特方程所示的关系发生变化：

变色范围 理论变色点 指示剂选择：使 落在滴定突跃范围之内。例如 Cr 2O 72-(黄色) + 6 Fe 2+ + 14 H + = 2Cr 3+（绿色）+ 6Fe 3+ + 7H 2O 需外加本身发生氧化还原反应的指示剂，如二苯胺磺酸钠指示剂，紫红→无色。 指示剂变色的电势范围为： 'In In 0.059 (V)E E n θ?≤± （考虑离子强度和副反应） 氧化还原指示剂的选择：指示剂的条件电势尽量与反应的化学计量点电势一致。 （4）常用的氧化还原指示剂 ① 二苯胺磺酸钠： H + 氧化剂 二苯胺磺酸钠 二苯胺磺酸 二苯联苯胺磺酸 （还原型） （无色） 氧化剂 二苯联苯胺磺酸紫（紫色）（氧化型） 反应的 n =2，变色电位范围：2059.085.0-~2 059.085.0+ 即 0.82 ~ 0.88 (V) 二苯胺磺酸钠指示剂空白值： 产生原因：a.指示剂用量；b.滴定剂加入速度、被滴定剂浓度及滴定时间等因素有关 消除办法：用含量与分析试样相近的标准试样或标准溶液在同样条件下标定K 2Cr 2O 7 。

线粒体自由基与衰老之间的关系

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一 一、学习第七章第一节，完成： 1、氧化还原反应是一类物质间有的反应。其基本特征是反应前、后元素的发生了变化。失去电子氧化数的物质称为还原剂，获得电子氧化数的物质称为氧化剂。 2、确定氧化值的规则： 3、任何氧化还原反应都是由两个“”组成的。在半反应中，同一元素的两个不同氧化值的物种组成了。任何氧化还原反应系统都是由电对构成的。 4、离子-电子法配平氧化还原反应的步骤及H、O配平规律。 二、学习第七章第二节，完成： 1、原电池是由两个“”组成的。 下列有关Cu-Zn原电池的叙述中错误的是( )。 A.盐桥中的电解质可保持两个半电池中的电荷平衡 B.盐桥用于维持氧化还原反应的进行 C.盐桥中的电解质不能参与电池反应 D．电子通过盐桥流动 KI溶液在空气中放置久了能使淀粉试纸变蓝，其原因涉及到电极反应________与电极反应 . 2、书写原电池符号的规则： （1）由氧化还原反应2FeCl3+Cu→2FeCl2+CuCl2构成的原电池，用

符号表示为 ，负极发生的电极反应为 ，正极发生的电极反应为 。） （2）反应2Mn04 (aq) +l0Br -(aq) +16H +( aq) 2Mn 2+ (aq)+5Br 2 (l)+8H 2 O(l)的电池符号为 。 3、当通过原电池的电流趋于零时，两电极间的最大 被称为原电池的电动势，以 E MF 表示之。可用电压表来测定电池的电动势。测量原电池的电动势与 有关。当电池中各物种均处于各自的标准态时，测定的电动势称为标准电动势，以 θMF E 表示。 反应2HgCl 2( aq) +SnCl 2 (aq) SnCl 4( aq)+ Hg 2 Cl 2(s)的θMF E 为0.503 2 θE （Sn 4+／Sn 2+）=0.153 9 V,则θE (HgCl 2/Hg 2Cl 2)为( )。 A.0. 322 V B O.784 V C.0.798 V D.0.657 1 V 4、原电池的最大功与Gibbs 函数： 4Ag(s)+4HCl(aq)+O 2(g) 4AgCl(s)+2H 2O(1),当c(HCl)=6.0 mol ．L -1,p(O 2)；100 kPa 时,298 K 下该反应的MF E 和θm r G ?分别为 ( )。 A.1. 099 V, -388.6kJ ．mol -1 B 1. 053 V,388.6 kJ.mol -l C 1. 190 V,-114.8 kJ. mol -l D.1.053V,-388.6 kJ. mol -l 三、学习第七章第三节，完成： 1、标准氢电极和甘汞电极的构造、图示、电对、电极反应及标准电极电势值：

氧化还原

§5—1 条件电位 一.能斯特方程 1.电对的分类 (1)可逆电对和不可逆电对 可逆电对:在氧化还原反应的任一瞬间都能迅速地建立起氧化还原平衡且实际电位遵从能斯特方程的电对称为可逆电对,如:Fe2+-e Fe3+、Fe3+/Fe2+ . 不可逆电对:在氧化还原反应的任一瞬间不能真正建立起按氧化还原反应所示的平衡的电对称为不可逆电对,如:MnO4-/Mn2+. (2)对称电对和不对称电对 对称电对:氧化态和还原态的系数相同的电对称为对称电对,如:Fe3++e Fe2+ . 不对称电对:氧化态和还原态系数不相同的电对称为不对称电对,如: Cr2O72-+14H++6e2Cr3++7H20 2.能斯特方程 (1)可逆氧化还原电对电位的计算公式—能斯特方程 对于均相可逆氧化还原电对 aA+bB+…+ne pP+qQ+… 式中E—电对电位,E°—电对的标准电位,a A、a B,…表示A、B,…的活度. R—气体常数,8.314J/(K·mol), T—绝对温度,F—法拉第常 数,96487C/mol,n—反应中的电子转移数. 注意:半反应中所有固态物质的活度为1,稀溶液中水的活度为1. 当t=25° C时, (2)利用平衡常数计算电对电位 例:(略) 二.条件电位 1.定义 由上述讨论知,要根据能斯特方程计算氧化还原电对的电位,必须知道有关组分的活度,这在实际上常常是不可能的.在分析化学中,参与半反应各物质及生成各物质的总浓度是容易知道的,因此若以总浓度代替活度计算氧化还原电对的电位将带来极大的方便,为此,必须校正由(i)离子强度、(ii)有关组分的副反应引起的误差.要校正这两个因素造成的误差就必须在能斯特方程中引入α和γ 对于前述半反应: a A=[A]γA=C AγA/αA a B=[B]γB=C BγB/αB … 当浓度比时, 则 —条件电位,它是在特定的条件下,氧化态和还原态 的条件浓度比(浓度均为1mol/L)为1时的实际电位.在离子强度I、 副反应系数α等条件不变时为一常数.关于需作以下说明: (1)许多情况下,I、α不一定不变,故并不真正是一常数,只能用作一些近似计算,但误差比用E°小得多.

丙烯酰胺水溶液聚合的几种氧化还原引发体系的研究.

1997年1月 精细石油化工 第1期 SPEC I AL IT Y CH E M I CAL S 丙烯酰胺水溶液聚合的几种氧化还原引发体系的研究 (, 100083 4种重要氧化还原引发体系进行了研究。从引发机理出发, 通过实验探讨了引发剂种类、引发剂浓度对聚丙烯酰胺分子量的影响。 关键词:丙烯酰胺聚丙烯酰胺引发剂聚合分子量 丙烯酰胺(AM 单体在水溶液中聚合时, 其聚合物分子量的大小与引发剂种类及浓度、引发温度、体系pH 值、单体浓度及单体质量等诸多因素都有密切的关系。通过使用不同的引发体系, 可以合成不同分子量的聚丙烯酰胺(PAM 。不同分子量的PAM 在不同的领域有不同的应用。研究引发体系与分子量的关系, 以便合成不同分子量的PAM 产品, 以满足不同领域的需要具有重要意义。迄今为止, 国内外大量报道了有关不同分子量PAM 的合成方法, 分子量范围从几万到上千万。目前国内的研究热点主要集中在高分子量PAM 的研制。本文主要对AM 水溶液聚合的四 酸铈铵, A R ; 硫脲, CP ; 去离子水。 聚合瓶, 通氮装置, 恒温水浴, 乌氏粘度计。1. 2实验方法 将AM 溶于去离子水中, 配成一定浓度的溶液, 加入pH 调节物质, 在适当温度下加入适量引发剂引发聚合, 得聚合物胶状样品。在1M N aC l 溶液中用乌氏粘度

计测得聚合物分子量[1]。用[Γ]=3. 73×10-4MW 0. 66计算分子量。式中[Γ]为特性粘数, MW 为PAM 分子量。2实验结果和讨论 AM 在水溶液中聚合时, 主要使用的是水溶性的氧化剂和还原剂; 氧化剂和还原剂构成了氧化还原体系。氧化还原体系通过电子转移反应, 生成中间产物自由基而引发聚合。氧化还原引发体系的活化能较低, 可使引发剂分解速率和聚合速率大大提高, 使诱导期缩短, 在较短的时间内, 就 收稿日期:19960414; 修改稿收到日期:19961202。 种氧化还原引发体系进行了研究。1实验部分 1. 1实验原料和仪器 丙烯酰胺, 工业品, 日本三井氰胺公司产; 过硫酸铵, A R ; 亚硫酸氢钠, A R ; 过氧化氢叔丁基, CP ; 亚硫酸钠, A R ; 硫酸亚铁, CP ; 氯酸钠, A R ; 硝 terpo lym er (EPDM w as characterized by infrared sp ectra , chem ical analysis and con tact angle again st w ater . T he graft copo lym erizati on of bu tylene acrylate on to random ethylene p ropylene diene ter 2 po lym er w ith benzoyl p erox ide as in itiato r and xylene as so lven t w as studied by o rthogond op ti m um design techn ique , and the conditi on of graft copo lym erizati on fo r h ighest grafting yield w as ob tained , m o reover , the effects of the conditi on s on the grafting yield w ere p reli m inary discu ssed . Keywords :graft copo lym erizati on ; grafting yield ; o rthogond op ti m um design techn ique ; EPDM ; BA

实验氧化还原反应和氧化还原平衡

实验氧化还原反应和氧化 还原平衡 The Standardization Office was revised on the afternoon of December 13, 2020

实验15 氧化还原反应和氧化还原平衡 [实验目的] 1. 学会装配原电池； 2. 掌握电极的本性、电对的氧化型或还原型物质的浓度、介质的酸度等因素对 电极电势、氧化还原反应的方向、产物、速率的影响； 3. 通过实验了解化学电池电动势。 [基本操作] 1. 试管操作 要用专用滴管取液体，不得引入杂质。清洗滴管时，里外都要冲洗干净。滴瓶上的滴管不得用于别的液体的取用，滴加液体时磨口以下部分不得接触接收容器的器壁。装有药品的滴管不得横放或滴管口向上斜放，以免液体流入橡皮头中。在通常的性质实验中，反应液一般取3~5滴。正常滴管中的一滴溶液约 mL ，例如，取 mL 的溶液，需要大约10滴。 2. 盐桥的制法 3. 伏特计的使用（区分正负极，伏特计和电极要接触良好） [实验原理] 对于电极反应： 氧化态（Ox ）+ ne ? = 还原态（Red ） 根据能斯特公式，有 ] [] [lg 0.05915][][ln F R o o 还原型氧化型还原型氧化型n E n T E E +=+ = 其中，R = J·mol -1·K -1，T = K ，F = 96485 C·mol -1 电极电势的大小与E o （电极本性）、氧化态和还原态的浓度，溶液的温度以及介质酸度等有关。 对于电池反应， aA + bB = cC + dD 对应的能斯特方程是 b a d c n E E B] [[A]D][[C]lg 0.05915o -=池 池 电极电势愈大，表明电对中氧化态氧化能力愈强，而还原态还原能力愈弱，电极电势大的氧化态能氧化氧化电极电势比它小的还原态。E + > E －是氧化还原 反应自发进行的判椐。在实际应用中，若o +E 与o -E 的差值大于Ｖ，可以忽略浓 度、温度等因素的影响，直接用o 池E 数值的大小来确定该反应进行的方向。 [实验内容]

呼吸链依赖性纯化线粒体氧化应激活性氧高质荧光测定试剂盒

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