The document describes the preparation and photocatalytic activity of alkali titanate nano materials. Specifically, it discusses how lithium titanate, sodium titanate, and potassium titanate nano crystals were successfully synthesized using a novel hydrothermal process. Characterization of the materials found they had different morphologies - lithium titanate formed snowflake structures while sodium and potassium titanate formed nanorods. Testing showed the materials had higher photocatalytic activity for degrading chloroform under UV light than a commercial titanium dioxide photocatalyst. The addition of nickel oxide as a cocatalyst further improved the photocatalytic activity, with potassium titanate showing the highest activity.

1. PREPARATION AND PHOTOCATALYTIC
ACTIVITY OF ALKALI TITANATE
NANO MATERIALS
DEPARTMENT OF METALLURGY AND MATERIALS
ENGINEERING
VEER SURENDRA SAI UNIVERSITY OF TECHNOLOGY
BURLA
Under the guidance of-
Gautam Behera
(Assistant Professor)
Submitted by-
Soumya Ranjan Sahoo
15010843

2. ABSTRACT
Photocatalysts nano A2TinO2n+1 (A = Li, Na, K) were
prepared successfully by novel hydrothermal synthesis process.
The nano crystals of Li2TiO3 were self-assembled as
snowflakes while that of Na2Ti3O7 and K2Ti8O17 were
nanorods. The results indicated that alkali titanates as prepared
have higher photocatalytic activities compared with P25TiO2 in
the degradation of chloroform under UV light irradiation. A
combination of K2Ti8O17 and NiO produces a photo catalyst
effective for the degradation of chloroform in aqueous solution.

3. INTRODUCTION
 Alkali titanates with the formula of A2TinO2n+1 consist of
titanium oxide layers and inter-layer cations and have unique
layered and tunnel-like crystal structure, which gives a
effective ion exchange and intercalation properties.
 Applications of alkali titanates are in photo cleavage of water,
photocatalysis, and fuel cell electrolytes.
 In this paper, photocatalysts nano alkali titanates A2TinO2n+1
(A = Li, Na and K) were firstly prepared by a novel
hydrothermal process with titanium tetrachloride as the
titanium source. The structure properties and photocatalytic
activities of the alkali titanates to degrade organic pollutants in
water were investigated.

4. EXPERIMENTAL PROCEDURE
The photocatalysts loaded with cocatalysts NiO by an impregnation
method were reduced by hydrogen at 250 C for 4 h, followed by
oxidization at 200 C for 2 h.
Then washing the product using distilled water and finally dried at 60C
for 3h.
The resulting white precipitate was stirred for 10 min. Transferred into a
Teflon lined stainless autoclave, sealed, and maintained at 180 C for 48h.
In the concentration , 25 mol /l AOH (A = Li, Na and K) aqueous
solution was added. And got a white precipitate.
Titanium tetrachloride (TiCl4) was dissolved in 30 ml acid solution to
get a concentration.

5. CHARACTERIZATION OF
PHOTOCATALYST
 X-ray powder diffraction (XRD) patterns of the
photocatalysts were obtained using a Philip X’pert
diffractometer with Cu Kα radiation.
 Field-emission scanning electron microscope, transmission
electron microscopy were used to observe the morphology
and dimension of the samples.

6. EVALUATION OF PHOTOCATALYTIC
ACTIVITY
 Photocatalytic reactivity of each sample was quantified in
terms of photocatalytically oxidation of CHCl3 to form
CO2 and HCl in the liquid phase, according to the
following reaction:
CHCl3 +H2O + 0:5O2 =CO2 +3HCl
 The yield was determined by measuring the Cl-
concentration by using a chloride ion selective electrode.
 The photocatalytic activities of sodium titanate under
visible irradiation were also carried out. In the
photoreactor shown in Fig. 1b, So the degradation of
colorless pollutant CHCl3 on the Na2Ti3O7 sample was
also evaluated.

8. RESULTS AND DISCUSSION
XRD ANALYSIS-
 Fig. 2a showed the XRD patterns of lithium titanate. It can be
mainly indexed to Li2TiO3 phase with face-centered cubic
structure and a small quantity of LiTiO2 phase with hexagonal
structure. The absence of very sharp peaks suggests that the
Li2TiO3 products are not highly crystalline and crystallite sizes
are small.
 The XRD patterns of sodium and potassium titanates were
shown in Fig. 2b and c, which can be indexed to a pure
Na2Ti3O7 phase with monoclinic structure and a pure
monoclinic phase of K2Ti8O17 respectively.

9. Fig 2 (a): XRD Pattern of Li2TiO3

10. Fig 2(b): XRD Pattern of sodium titanate

11. Fig 2(c): XRD Pattern of potassium titanate

12. ANALYSIS OF MORPHOLOGIES OF ALKALI
TITANATES-
 Fig. 3a shows the morphology of lithium titanate. The
Li2TiO3 nano crystals whose average size is 50 nm self-
assembled as snowflakes.
 Fig. 3b and c shows the morphologies of sodium and
potassium titanates, which have average diameters of 50 nm
and 30 nm, respectively, with lengths up to several
micrometers.

15. Fig. 3. Scanning electron micrographs of alkali titanates. (a) Li2TiO3; (b)
Na2Ti3O7; (c) and (d) K2Ti8O17 samples prepared by hydrothermal
method at 180 8C and 240 8C, respectively.

16. Fig. 4. A TEM image of K2Ti8O17 nano wires prepared by hydrothermal
method. Inset: electron diffraction recorded along the <0 0 1> zone axis
indicates the growth along the (0 1 0) direction.

17. PHOTOCATALYTIC ACTIVITIES OF ALKALI
TITANATES-
 The photocatalytic activities of A2TinO2n+1 (A = Li, Na, K)
increased in the order Na > K > Li.
 Since the sodium titanate has a strong and wide
absorption in the visible-light region, the photocatalytic
activity of Na2Ti3O7 under visible-light irradiation was
also evaluated, which was carried on the basis of the
photodegradation percents of Methene Blue (MB) and
CHCl3 in aqueous solution.

18. EFFECTS OF NIO COCATALYST ON THE
PHOTOCATALYTIC ACTIVITIES OF ALKALI
TITANATES-
 As shown in Fig. 5, the photocatalytic activities of NiO-A2TinO2n+1 (A
= Li, Na, K) increased in the order K > Na > Li. K2Ti8O17 showed the
highest photocatalytic activity when NiO cocatalysts were loaded.
Fig. 5. Degradation of
chloroform on (a) NiO-
K2Ti8O17, (b) NiO- Na2Ti3O7
and (c) NiO- Li2TiO3
photocatalysts under UV light
irradiation.

19. CONCLUSION
 Photocatalysts A2TinO2n+1 (A = Li, Na, K) nano materials
were prepared successfully by hydrothermal synthesis
process.
 The alkali titanates as prepared have higher photocatalytic
activities compared with P25 TiO2 in the degradation of
chloroform under UV light irradiation.
 A combination of K2Ti8O17 and Ni species produces a
photocatalyst effective for the degradation of chloroform in
aqueous solution.
 The framework of the tunnel structure is suitable for
accommodating cocatalysts such as NiO to induce a strong
interaction between the active species and cocatalysts.
 Na2Ti3O7 has high photocatalytic activity under visible-light
irradiation due to its strong absorption in the visible light
region.