Catalytic wet oxidation of chlorinated organics at mild conditions over iron doped nanoceria

Accepted Manuscript Catalytic wet oxidation of chlorinated organics at mild conditions over iron doped nanoceria

Manju Kurian, V.R. Remya, Christy Kunjachan PII: DOI: Reference:

S1566-7367(17)30229-7 doi: 10.1016/j.catcom.2017.05.028 CATCOM 5064

To appear in:

Catalysis Communications

Received date: Revised date: Accepted date:

15 March 2017 29 May 2017 29 May 2017

Please cite this article as: Manju Kurian, V.R. Remya, Christy Kunjachan , Catalytic wet oxidation of chlorinated organics at mild conditions over iron doped nanoceria. The address for the corresponding author was captured as affiliation for all authors. Please check if appropriate. Catcom(2017), doi: 10.1016/j.catcom.2017.05.028

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ACCEPTED MANUSCRIPT Catalytic wet oxidation of chlorinated organics at mild conditions over iron doped nanoceria Manju Kurian* , Remya V.R, Christy Kunjachan

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Department of Chemistry, Mar Athanasius College, Kothamangalam-686666, India.

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Address,

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Department of Chemistry, Mar Athanasius College,

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Kothamangalam,

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India.

E-mail ID: [email protected]

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Tele fax: 91485 2822512

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PIN 686666

ACCEPTED MANUSCRIPT Catalytic wet oxidation of chlorinated organics at mild conditions over iron doped nanoceria Manju Kurian* , Remya V.R, Christy Kunjachan Department of Chemistry, Mar Athanasius College, Kothamangalam-686666, India.

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Abstract Degradation of 4-chlorophenol, 2,4-dichlorophenol and 2,4-dichlorophenoxy acetic acid was

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investigated by wet air oxidation over Cex Fe1-x O2 (x: 0, 0.25, 0.5, 0.75, 1) nanocatalysts. ambient

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Complete removal of target pollutants could be effected at atmospheric pressure and near conditions with considerable decrease in TOC

and

COD.

4-chlorophenol

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(1000mg/L) was completely degraded with 59.66% TOC and 84.9% COD removal at 40℃ over Ce0.75 Fe0.25 O2 catalyst whereas 2,4-dichlorophenol (1250mg/L) conversion with 74.3% TOC and 93.62% COD removal was observed at 50o C over Ce0.75 Fe0.25 O 2 catalyst. The

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activity of the catalysts was found to increase on repeated runs. Keywords: Ce-Fe oxides, catalytic wet air oxidation, 4-chlorophenol, 2,4-dichlorophenol, 2,4-

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dichlorophenoxy acetic acid, catalyst reusability.

ACCEPTED MANUSCRIPT Introduction Degradation of toxic compounds from water bodies is a perpetual problem faced by governments and local bodies worldwide. Chlorophenols(CPs) are a class of persistent pollutants that are toxic, hardly biodegradable and difficult to remove from environment that are commonly used as pesticides, herbicides, and disinfectants [1]. CPs are listed as priority toxic pollutants in both the US EPA Clean Water Act and the European Decision 2455/2001/EC [2-4]. Several methods are available for the elimination of CPs from water

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such as activated carbon adsorption [5], supercritical water oxidation [6], enzymatic degradation [7], Fenton process [8], wet peroxide oxidation [9-10] etc.

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Wet air oxidation (WAO) represents a green technique to treat wastewaters polluted

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by non-biodegradable compounds. It employs molecular oxygen as oxidising agent and generally requires high temperature and pressure for complete degradation of pollutants. With

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the use of oxygen, chlorinated organic contaminants are converted to CO 2 , H2 O and HCl. However, at high temperature and pressure, corrosion problems can arise due to the elimination of HCl and therefore, low temperature and pressure are favoured. Use of catalysts

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for WAO or Catalytic Wet Air Oxidation (CWAO) has been attempted over several catalysts to reduce the operating temperature and pressure, none of which are cost effective [11-14]. In

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this context, catalytic wet air oxidation of 4-chlorophenol (4 CP), 2,4 dichlorophenol (2,4 DCP) and 2,4 dichlorophenoxy acetic acid (2,4 D) was studied at atmospheric pressure with iron doped nanoceria as catalyst. The influence of reaction conditions on the catalyst behavior

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such as temperature, oxygen pressure, pollutant concentration and catalyst load were investigated. Reusability of the catalysts was also checked for five consecutive cycles.

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2. Experimental

Cerium(III) nitrate hexahydrate (Ce(NO 3 )3 .6H2 O) by Aldrich Chemical Co. Inc. (St. Louis, MO, USA), iron(III) nitrate nonahydrate (Fe(NO 3 )3 .9H2 O) and ammonia (Merck Chemicals, Mumbai,India) were used for the preparation of oxide catalysts. For catalytic activity studies, 4-chlorophenol and 2,4-dichlorophenol (Loba Chemie) 2,4-dichlorophenoxy acetic acid (Himedia Laboratories), silver sulphate, mercury sulphate, sulphuric acid, ferrous ammonium sulfate and potassium dichromate (Merck Chemicals, India) were used as obtained. Requisite quantities of Ce and Fe precursors were dissolved separately in deionized water and mixed together. Dilute aqueous solution of ammonia was added drop wise to this solution with magnetic stirring at ambient temperature until the precipitation was complete (pH~10). The resulting slurry was stirred for further two hours, filtered off and washed

ACCEPTED MANUSCRIPT several times with distilled water until free from anionic impurities. The obtained precipitate was oven dried at 110 ℃ and calcined at 700 ℃ for 5 hours [15]. CWAO experiments were carried out on a down flow fixed bed reactor consisting of a packed bed reactor placed inside a temperature-controlled furnace. The preheated pollutant solution was introduced at the top of the reactor using a HPLC grade water pump. The oxygen source was high purity air containing 21% oxygen, fed to the system through an electronic gas-flow controller. The

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product samples withdrawn at periodic intervals were analysed using Perkin Elmer Clarus 580 Gas Chromatograph equipped with an Elite-5 capillary column. The results are expressed as percentage removal of pollutants. The extent of oxidation and total organic carbon (TOC)

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removal was measured using chemical oxygen demand (COD) measurements with Shimadzu

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TOC-L analyzer and standard dichromate method respectively. Removal percentage of chemical oxygen demand (COD) was calculated as {[COD]0 – [COD]t /[COD]0 }x 100 where

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[COD]0 and [COD]t are CODs at initial and at time of study respectively. The error percentage between the results of analyses is less than 5%. The reaction intermediates of 4CP, DCP and 2,4-D were identified by GC-MS analysis on a Varian 1200 L Single

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Quadruple spectrometer using Helium as the carrier gas. All experiments were repeated and

3. Results and discussions

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averages are reported.

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3.1 Optimisation of reaction variables

The optimization of reaction variables for conducting CWAO in an economical way is of utmost importance and was thoroughly studied attempted with respect to reaction

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parameters such as temperature, oxidant concentration, pollutant concentration, and catalyst dosage. Ce0.75 Fe0.25 O 2 catalyst was selected as model catalyst for the study. To examine the effect of temperature in the air oxidation of the target pollutants, reactions were performed at five different temperatures (35, 40, 50, 60, and 75°C) keeping all other reaction variables constant. The kinetics of removal of 4 CP, DCP and 2,4-D over Cex Fe(1-x)O2 nanocatalyst at different temperatures are presented in Table 1. The kinetic curves show that complete removal of the target pollutants is observed at all temperatures under study. Residual TOC and COD measurements indicate the presence of persistent intermediates. The reaction intermediates

of

chlorinated

organics

identified

by

GC-MS

analysis

are

phenol,

benzoquinone and 2,5-hexane dione. GC-MS data clearly evidence the absence of chlorinated intermediate organic compounds. The temperature for maximum removal of TOC and COD

ACCEPTED MANUSCRIPT increases with the complexity of the molecule as expected (2,4 D > DCP > 4 CP). With 4 CP, maximum TOC (36.8%) and COD (76.5%) removal is observed at 40o C. 2,4-DCP removal occur at a maximum at 50o C with 55.1% TOC and 78.9% COD removal respectively. For 2,4-D, the maximum conversion is observed at 80°C with 70.9% TOC and 86.4% COD removal. With increase in temperature, the pollutant molecules undergo instantaneous collision and the adsorption probability between the pollutant molecules and the catalytic active site increases resulting in high conversions. Also, increase in temperatures increases

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the kinetic energy of the molecules thereby facilitating the attainment of the activation energy easily. Therefore, optimized temperatures for the wet air oxidation of 4-CP, 2,4-D and 2,4-D

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were set as 40o C, 50o C and 80o C respectively. Further increase in optimised temperatures

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decreases the reaction rate in all cases. The decrease in removal rate at higher temperatures

4-CP removal %

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was probably because of the auto scavenging mechanism of hydroxyl radicals [16, 17].

2,4-DCP removal %

GC

TOC

Room temperature

100

25.59 49.18 86.69 21.04 35.25

40

100

36.79 76.58 100

50

100

60

100

80

-

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TOC

COD GC

50.55 70.82

TOC

COD

-

-

-

-

-

40.62

54.26 100

55.09 78.95 100

22.3

26.6

53.83 100

48.05 69.43 100

20.51 36.35

27.48 58.42 100

51.94 75.26 100

33.1

62.28

100

70.9

86.54

100

36.3

72.66

-

-

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90

100

GC

26.8

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70

COD

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Temperature (℃)

2,4-D removal %

-

-

-

-

-

-

Table 1. Effect of temperature on the removal of (a) 4-CP (b) 2,4-DCP (c) 2,4-D Reaction conditions: 500mg Ce0.75 Fe0.25 O2 , Airflow: 4-CP- 5ml/min, 2,4-DCP

- 8ml/min,

2,4-D - 2ml/min, 4 CP/ DCP/ 2,4 D concentration- 500 mg/L The effect of pollutant concentration on catalytic wet air oxidation was studied by taking five different concentrations of 250, 500, 750, 1000, 1250mg/L solutions of 4 CP, 2,4 DCP and 2,4 D (Table 2). 4-CP, 2,4-DCP and 2,4-D shows complete conversion at all concentrations under study. TOC removal increases from 33.4 to 59.6% with increase in 4CP concentration from 250 to 1000mg/L which then decreases slightly to 56.3% for 1250mg/L. In the case of 2,4-DCP, maximum TOC (74.3%) and COD (90.3%) removal is

ACCEPTED MANUSCRIPT observed at 1250mg/L. The TOC and COD removal for 2,4 D increases and reaches maximum at 500mg/L, then decreases. The decrease in oxidation efficiency at higher reactant concentrations can be attributed to the fact that at higher pollutant concentration, more number of intermediates are formed which compete for the limited amount of oxygen present in the system as the oxygen partial pressure in constant [18]. In WAO, it must be noted that the degradation rate is strongly limited by the mass transfer of molecular oxygen from the gas to the liquid phase. Also, the rate of degradation depends on the hydroxyl radicals generated

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and these radicals are used up for initial breakdown of the molecule and thus unavailable for

4 CP/ DCP/ 2,4 D 4-CP removal % TOC

250

100

33.4

500

100

750

100

1000

100 100

(mg/L)

COD GC

2,4-D removal %

TOC

COD GC

TOC

COD

70.9

100

24.4

32.6

100

26.4

48.9

36.8

76.5

100

55.1

78.9

100

70.9

86.4

40.9

78.9

100

59.2

84.2

100

59.9

70.8

59.6

84.2

100

55.0

77.3

100

60.4

74.5

56.3

82.4

100

74.3

90.3

100

56.3

64.8

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1250

2,4-DCP removal %

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GC

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concentration

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further degradation.

Table 2. Effect of pollutant concentration on wet oxidation

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Reaction conditions: Catalyst- 500mg Ce0.75 Fe0.25 O2, Temperature: 4-CP- 40o C , 2,4-DCP 50o C and 2,4-D - 80o C, Airflow: 4-CP- 5ml/min, 2,4-DCP - 8ml/min, 2,4-D - 2ml/min. Effect of catalyst dosage on the kinetics of wet air oxidation was checked with different catalyst loadings of 0, 250, 500, 750 and 1000 mg (Table 3). In order to study the role of catalyst, a blank run was conducted without catalyst. In the absence of catalyst, 25.2% degradation occur for 4-CP. TOC removal % increases from 17.5 to 52.3%, on increasing catalyst dosage from 0 to 1000mg. 2,4 DCP and 2,4 D are degraded completely in the absence of catalyst, which may be attributed to the higher operating temperatures which were optimised

earlier. On increasing the catalyst loading, TOC and COD removal rates can be

improved. 2,4-DCP shows maximum TOC and COD removal for 250mg catalyst load which

ACCEPTED MANUSCRIPT decreases on increasing the dosage above 250mg. In the case of 2,4-D, maximum TOC and COD removal percentage of 70.9% and 86.4% respectively is observed for 500mg catalyst. The decrease in the oxidation efficiency at higher catalyst loading can be attributed to the fact that at higher catalyst loading the rate of destruction of free radicals also is high [19]. At initial stages, the degradation rate is high due to generation of more free radicals that leads to enhanced mineralization. However, the hydroxyl radicals are short lived species and are destructed by collisions with each other or with other radicals as well as with reactor walls.

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Thus, the oxidation efficiency is reduced at higher catalyst loading. So, considering the TOC and COD removal, 500 mg of catalyst is decided as the optimal dosage for the catalytic wet

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air oxidation.

Catalyst

4-CP removal %

2,4-DCP removal %

2,4-D removal %

load (mg)

GC

TOC

COD

GC

0

25.2

17.5

32.3

250

38.7

32.5

500

100

36.8

750

93.7

47.3

1000

100

52.3

COD

GC

TOC

COD

100

60.9

82.9

100

31.5

56.5

65.8

100

65.8

88.2

100

46.8

60.3

76.5

100

55.1

78.9

100

70.9

86.4

70.2

100

55.0

70.2

100

47.1

63.9

78.4

100

64.3

86.9

100

30.0

52.6

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TOC

Table 3. Effect of catalyst load on removal of (a) 4-CP (b) 2,4-DCP (c) 2,4-D Reaction conditions: Catalyst- Ce0.75 Fe0.25 O2, Temperature: 4-CP- 40o C , 2,4-DCP - 50o C

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and 2,4-D - 80o C, Airflow: 4-CP- 5ml/min, 2,4-DCP - 8ml/min, 2,4-D - 2ml/min, 4 CP/ DCP/ 2,4 D concentration- 500 mg/L The rate of oxidant feed is an important parameter for WAO reactions and the effect of airflow on the catalytic degradation of 4-CP, 2,4-DCP, 2,4-D was checked in the present study by keeping an air feed containing 21% O 2 and 79% N 2 constant (Table 4). In the case of 4-CP, maximum degradation occurred at an airflow of 5ml/min with 36.8% TOC and 76.5% COD removal. Maximum percentage removal of 2,4-DCP occurred at 50o C at airflow 8ml/min with 55.0% TOC and 78.9% COD removal. 2,4-D shows complete conversion with 70.9% TOC and 86.5% COD removal at airflow 2ml/min. Optimized airflow for 4-CP, 2,4DCP and 2,4-D were 5ml/min, 8ml/min and 2ml/min respectively.

ACCEPTED MANUSCRIPT 4-CP removal%

2,4-DCP removal %

2,4-D removal %

(ml/min)

GC

TOC

COD

GC

TOC

COD

GC

TOC

COD

0

100

32.9

65.8

100

42.7

50.9

100

16.9

26.3

2

100

34.2

69.3

100

44.8

52.3

100

70.9

86.4

5

100

36.8

76.5

100

51.3

74.5

100

22.3

41.2

8

100

22.5

42.1

100

55.0

78.9

100

30.9

63.5

10

100

29.3

58.7

100

60.2

80.2

100

25.7

46.6

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Airflow

Table 4. Effect of air flow on removal of (a) 4-CP (b) 2,4-DCP (c) 2,4-D

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Reaction conditions: Catalyst- 500mg Ce0.75 Fe0.25 O2, Temperature: 4-CP- 40o C , 2,4-DCP -

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50o C and 2,4-D - 80o C, 4 CP/ DCP/ 2,4 D concentration- 500 mg/L.

The catalytic efficacy of iron doped ceria nanoparticles was studied for wet air

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oxidation reaction of 4-CP, 2,4-DCP, 2,4-D under the optimised conditions (Table 5). The order of 4-CP removal is Ce0.75 Fe0.25 O 2 > CeO 2 >Fe2 O3 > Ce0.5 Fe0.5 O2 > Ce0.25 Fe0.75 O 2 . The extent of removal of 2,4-DCP, follows the order of Ce0.75 Fe0.25 O2 > Ce0.25 Fe0.75 O2 > Fe2 O3 >

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Ce0.5 Fe0.5 O2 > CeO 2 . 2,4-D removal follows the order Ce0.75 Fe0.25 O2 > CeO 2 > Ce0.25 Fe0.75 O2 > Ce0.5 Fe0.5 O2 >Fe2 O3 . It can be safely commented that iron loading to the crystal lattice of

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ceria increases the oxidation capacity of ceria nanoparticles. A similar observation was reported for wet peroxide oxidation of 4-CP, 2,4 DCP and 2,4 D over iron doped nanoceria in our previous publication. However, it is quite interesting to note that though iron doping

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increases the catalytic activity of nanoceria, the activities of individual catalysts varies as the oxidant is varied, suggesting a change in mechanism. As reported earlier, the extent of removal

of

4-CP,

TOC

and

COD

follow

the

order

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Ce0.25 Fe0.75 O 2 >Ce0.5 Fe0.5 O2 >Ce0.75 Fe0.25 O2 >Fe2 O3 , >CeO 2 for wet peroxide oxidation whereas for 2,4-DCP the order is Ce0.5 Fe0.5O2>Ce0.25Fe0.75O2>Ce0.75Fe0.25 O 2 >Fe2 O3 >CeO 2 . The efficiency of catalysts follows the order of Ce 0.25 Fe0.75 O2 > Ce0.5 Fe0.5 O2 > Fe2 O3 > Ce0.75 Fe0.25 O2 > CeO 2 for 2,4 D [20]. 4-CP removal%

2,4-DCP removal %

2,4-D removal%

Catalyst

GC

TOC

COD

GC

TOC

COD

GC

TOC

COD

CeO 2

83.5

46.6

68.5

100

30.6

62.5

100

44.9

63.2

Ce0.25 F0.75 O2

78.3

34.2

50.9

100

56.9

82.3

100

40.0

60.5

Ce0.5 Fe0.5 O2

78.4

36.9

53.2

100

45.2

70.2

100

25.1

49.3

Ce0.75 Fe0.25 O2

100

59.6

84.2

100

74.3

93.6

100

62.6

77.3

ACCEPTED MANUSCRIPT Fe2 O 3

69.6

38.8

65.8

100

49.9

73.2

100

22.19 43.5

Table 5. Data on catalytic degradation of 4-CP, 2,4-DCP and 2,4-D under optimised conditions. The determining factors in deciding the catalytic efficiency in heterogeneous catalysis

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are the surface area and the chemical structure of the catalyst. The textural and structural parameters of the catalysts under study were reported in our previous publications [15, 20].

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XRD and TEM analyses of Cex Fe1-x O2 (x: 0, 0.25, 0.5, 0.75, 1) revealed the presence of nanoparticles in all oxides beyond solid solution limit as detailed in our previous publication.

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Average crystallite sizes calculated from the corresponding diffraction peaks using DebyeScherrer equation ranged from 12.8 to 32.29 nm. The TEM images confirm the nanometric

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size of the prepared catalysts and average crystallite sizes were in the range of 12-65 nm. BET surface area and pore volume of synthesised composites were in the range of 30-10 m2 /g

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and 0.004-0.01cm3 /g. The surface area and pore volume of the ceria nanoparticles increased as a result of iron substitution. Raman analysis indicated that iron incorporated ceria lattice had improved surface reducibility as a result of oxygen vacancy formation and gradual

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shrinkage of the unit cell. FT-IR spectra revealed the characteristic Ce-O stretching and crystalline water absorption of synthesised nanoparticles. Thermal analysis data showed these

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oxides to be thermally stable.

The stability of the catalyst during repeated uses is of paramount significance in heterogeneous catalysis. Therefore to check the reusability, we used the model catalyst

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Ce0.75 Fe0.25 O 2 catalyst for five continuous runs under the same operating conditions. Complete conversion is observed in all cases and it is interesting to note that the activity actually increases with time as indicated by TOC and COD removal percentages suggesting that the attainment of reaction equilibrium takes some time (Table 6). Slight increases in TOC and COD removal percentages are indicative of changes in intermediates/product selectivity. PXRD pattern of the recycled catalyst compared with the freshly synthesized catalyst indicate that the catalysts retain phase purity (Fig. 1). Average crystallite size remains more or less the same.

ACCEPTED MANUSCRIPT No. of

4-CP removal %

catalytic runs

GC

2,4-DCP removal %

2,4-D removal %

TOC

COD GC

TOC

COD GC

TOC

COD

100

34.4

52.2

100

70.8

85.8

100

52.2

63.2

2

100

40.4

58.3

100

72.5

90.0

100

58.2

70.4

3

100

41.2

55.6

100

72.4

89.5

100

55.6

68.5

4

100

45.2

60.0

100

71.6

88.2

100

60.1

74.2

5

100

45.2

62.3

100

73.4

92.6

100

62.3

76.3

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1

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Table 6. Reusability of Ce0.75 Fe0.25 O2 under optimized reaction conditions

DCP

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Conclusions

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Fig. 1. PXRD pattern of Ce0.75 Fe0.25O 2 before and after catalytic reusability studies of 2,4-

Cex Fe1-x O2 (x: 0, 0.25, 0.5, 0.75, 1) nanocatalysts are effective catalysts for wet air oxidation of 4-CP, 2,4-DCP and 2,4-D pollutants at atmospheric pressure and near ambient conditions. Maximum efficiency for wet air oxidation is observed for Ce0.75 Fe0.25 O2 nanocomposite. The catalytic activity of the catalysts increased on repeated usage. Cex Fe1-x O2 oxides could be good alternatives for degradation of chlorinated organic contaminants to reduce the effluent toxicity. Acknowledgment Financial assistance from Kerala State Council for Science, Technology and Environment, India is gratefully acknowledged.

ACCEPTED MANUSCRIPT References 1. M. Pera-Titus, V. Garcıa-Molina, M.A. Banos, J. Gimenez, S. Esplugas,Degradation of chlorophenols by means of advanced oxidation processes: A general review, Appl. Catal. B: Environ. 47 (2004) 219–256. 2. K. Hayward, Drinking water contaminant hit-list for US EPA, Water 21 (1998) 4. 3. L.H. Keith, W.A. Telliard, Priority pollutants: a prospective view, Environ. Sci. Technol.

PT

13 (4) (1979) 416–424. 4. EC Decision 2455/2001/EC of the European Parliament and of the Council of November

RI

20, 2001 establishing the list of priority substances in the field ofwater policy and amending Directive 2000/60/EC (L 331 of 15–12-2001).

SC

5. Manuel Carmona, M Teresa Garcia, Angel Carnicer, Mercedes Madrid ´ and Juan Francisco Rodr´ıguez, Adsorption of phenol and chlorophenols onto granular activated

NU

carbon and their desorption by supercritical CO 2, J. Chem. Technol. Biotechnol. 2014; 89: 1660–1667

alkalis

on

the

dechlorination

MA

6. Jing Ma, Xiuqin Dong, Yingzhe Yu, Bangxing Zheng, Minhua Zhang, The effects of of o-chlorophenol in

supercritical water: Molecular

dynamics simulation and experiment, Chem. Eng. J., 241, 2014, 268–272

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7. M. Masuda, A. Sakurai, M. Sakakibara, Effect of reaction conditions on phenolremoval by polymerization and precipitation using Coprinuscinereus peroxidase, Enzyme Microb.

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Technol. 28 (2001) 295–300.

8. M.C. Lu, J.N. Chen, H.H. Huang, Role of goethite dissolution in the oxidationof 2chlorophenol with hydrogen peroxide, Chemosphere 46 (2000)131–136.

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9. M. Kurian, D.S. Nair, On the efficiency of cobalt zinc ferrite nanoparticles for catalytic wet peroxide oxidation of 4-chlorophenol, J. Environ. Chem. Eng. 2 (2014) 63-69. 10. M. Kurian, D.S. Nair, Manganese zinc ferrite nanoparticles as efficient catalysts for Wet Peroxide Oxidation of Organic Aqueous Wastes, J. Chem. Sci. 127(2015) 537-546. 11. Ning Li, Claude Descorme, Michele Besson, Catalytic wet air oxidation of chlorophenols over supported ruthenium catalysts, J. Hazardous Mater., 146 (2007) 602–609 12. Yuting Tu, Ya Xiong, Shuanghong Tian, Lingjun Kong, Claude Descorme, Catalytic wet air oxidation of 2-chlorophenol over sewage sludge-derived carbon-based catalysts, J. Hazardous Mater., 276, 2014, 88–96

ACCEPTED MANUSCRIPT 13. Bharati Deka, K.G. Bhattacharyya, Using coal fly ash as a support for Mn(II), Co(II) and Ni(II) and utilizing the materials as novel oxidation catalysts for 4-chlorophenol mineralization, J. Environ. Management, 150, 2015, 479–488 14. Nirupam

Khanikar, Krishna

G

Bhattacharyya,

Cu(II)-kaolinite

and

Cu(II)-

montmorillonite as catalysts for wet oxidative degradation of 2-chlorophenol, 4chlorophenol and 2,4-dichlorophenol, Chem. Eng. J., 233, 2013, 88–97 15. M. Kurian, C. Kunjachan, Effect of lattice distortion on physical properties and surface with incorporation of iron/zirconium, Nano-

PT

morphology of nanoceria framework

Structures & Nano-Objects 1 (2015) 15–23.

RI

16. Divya S Nair, Manju Kurian, Heterogeneous catalytic oxidation of persistent chlorinated

SC

organics over cobalt substituted zinc ferrite nanoparticles at mild conditions: Reaction kinetics and catalyst reusability studies, Journal of Environmental Chemical Engineering,

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5 (2017) 964–974.

17. Divya S Nair, Manju Kurian, Catalytic peroxide oxidation of persistent chlorinated organics over nickel-zinc ferrite nanocomposites, Journal of Water Process Engineering,

MA

17, (2017) 69–80.

18. G. Ovejero, A. Rodrguez, A. Vallet, J. Garca, Catalytic wet air oxidation of a non-azo dye

19. Anurag

Garg and Alok

ED

with Ni/MgAlO catalyst, Chem. Eng. J., 215-216 (2013) 168–173. Mishra,

Wet

Oxidation—An

Option

for

Enhancing

biodegradability of Leachate Derived From Municipal Solid Waste (MSW) Landfill, Ind.

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Eng. Chem. Res., 2010, 49 (12), pp 5575–5582 20. Manju Kurian, Christy Kunjachan, Asha Sreevalsan, Catalytic degradation of chlorinated organic pollutants over Cex Fe1-x O 2 (x: 0, 0.25, 0.5, 0.75, 1) nanocomposites at mild

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conditions, Chem. Eng. J., 308 (2017) 67–77.

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ACCEPTED MANUSCRIPT

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Graphical abstract

ACCEPTED MANUSCRIPT Highlights

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Iron doped ceria as efficient catalysts for wet air oxidation of chlorinated organics. The reaction occurred at atmospheric pressure and near ambient temperatures. Complete mineralization of target pollutants observed in all runs.

AC C

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