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Photo catalytic processes are well known in this age due to its precise and scientific implications. They consent to the opportunity of performing chemical reactions expected at the construction of fuels, the removal of pollutant, inactivation of bacteria etc. devoid of the concourse of elevated temperatures and pressures and by means of light as the energy participation. Heterogeneous photocatalysis on semiconductor surfaces has concerned a lot of consideration due to its immense and vital utilities in degradation, inclusive mineralization of organic contaminants and air purification etc.[1-3]

Newly many transition metals play an important role in photodegradation of dyes like  Amido black -10 B and bismark brown –R and Azure B dye were bleached by photo-fenton and Copper hexacyanoferrate(II) as semiconductor very  effectively and photodegrade different dye molecule to colourless less toxic products.[5]  Photocatalytic degradation of dyes ( methylene blue )using TiO₂ has been studied earlier.[6] Degradation of Copper complex is found step wise degradation ,along with metal- ligand breaking, unsaturated segment and saturated segment bond breaking.[7] The potential of the nanocomposites as aphotocatalyst was evaluated by photodegradation of methylene blue dye under visiblelight irradiation.  Photodegradation Studies of Copper Oxide–Graphene Nanocomposites was studied earlier. [8]

Spectral analysis and synthesis of a biologically vigorous molecule derived from natural edible oil Mustard, its complexation with ligand containing nitrogen and sulphur atom have been studied here. In the present work we have focused photcatalytic degradation of the Copper (II) Mustard Thio Urea complex under various light intensity.

Experimental 

Copper(II) Mustard Thiourea  complex was prepared by refluxing Copper Mustard soap with Thiourea   ligand in 1:1 stoicheomery in benzene for one hour. Firstly Copper Mustard soap was synthesised by refluxing (direct metathesis) Mustard oil in its pure form with alcohol and 1N KOH solution for 3 hour.[9] Neutralization of additional KOH was done by 1N HCl. Saturated solution of Copper sulphate was used for transform of neutralized potassium soap into Copper soap. The degradation was measured using optical density parameter and  decolorization of the solution was observed with definite time interval. Optical density was  measured in the presence of different doses of semiconductor Zinc oxide and irradiation at different light intensities .200 W tungsten lamp was taken for irradiating the complex solution in visible range as a light source for certain time period. Light intensity was deliberate with the support of a solarimeter (Suryamapi model CEL India Model SM 201).  visible spectrophotometer (SYSTRONIC MODEL 106) was used todetermine optical density of the solution at regular time interval. Table:1 has been shown spectral data to represent its structural aspects.

Photocatalytic degradation.

Copper soap and its complex are abbreviated as follows :
Copper- Mustard soap (CM)
Copper-Mustard -Thiourea complex (CMT)
Wave length at λ=680nm of spectrophotometer was applied for photocatalytic degradation of CMT complex. Plot of 2+log O.D. (absorbance) versus time was plotted and found linear.  ZnO was used as catalyst in benzene solution so heterogeneous photocatalysis pursue by pseudo-first-order reaction kinetics practically well.  Rate constants of this reaction were designed by this phrase.[10]
K= 2.303 x slope
Effect of light intensity:
The effect of light intensity on the photocatalytic degradation was at the optimum initial concentration (.0008 M) and catalyst dosage (.02 gm) in polar solvent (benzene) spectrophotmertically. As point out from the data it has been found that rate of photocatalytic degradation of CMT get an increases with rising in  light intensity initially due to the number of photon striking per unit area of semiconductor also raise , further increase in light intensity due to decrease in the degradation rate. Optical density was measured anda typical run has been shown in Figure: 1. Due to thermal-effect photocatalytic degradation was found to decrease with increase in light intensity. [10,11] . The results are tabulated in Table: 2 and presented graphically in Figure:2
Mechanism
On the basis of experimental observation, a tentative mechanism for photocatalytic degradation of Copper(II) Mustard Thiourea complex may be proposed as:
 
spectral and thermal studies also sustain the projected mechanism in which unsaturated  >c=c< site present in all the long chain fatty acid components of the  natural oil division of the complex molecules may reacts/ breaks /degrades first and the soap complex derived from the natural oils degrade comparatively faster than saturated segment of CMT complex [10,12]
The  Copper  Mustard Thiourea complexes become colourless due to some of Cu⁺² ion of the complex may reduced to Cu⁺ or Cu⁰ to some grade during the process of degradation by trapping photogenerated electron in the system.  The literature survey also disclose that the occurrence of oxygen may also influence the photodegradation of  complex  molecules as the main oxidation products of the esters are keto or hydroxy compounds .[13]  

Table:1 IR spectral data for Copper(II) Mustard soaps and Copper(II) Mustard Thiourea complex

Absorption bands	CM  (cm-1)
Corresponding to soap moiety
Olefinic =C-H stretching	3010
CH3 and CH2 , C-H Anti_sym. Streching(υas )	2930.7
CH3 and CH2,  C-H sym. Streching(υas )	2864.5
>C=O Streching	1718
COO-,C-O Anti_sym. Streching	1622.5
CH2 C-H bending(δ) scissoring	1464.2
COO-, C-O sym. Streching	1380
CH2 C-H bending(δ) (Twisting and wagging)	1330
CH3 , C-H Rocking	1118
CH2 C-H Rocking	731
Cu-O stretching
Corresponding to Ligand moiety
NH2 N-H stretching	3400 broad
C-N stretching	1428.6
N-C-S	1280
C=S  stretching	1250

Reported:[13]
Table :  2 Effect of Light intensity

S.No.	Intensity of light in Mwcm-2	K1X10-5	K2X10-5
1	18	10.87	4.31
2	22	14.71	5.91
3	26	18.55	11.35
4	30	12.79	13.75
5	34	14.07	2.23
6	38	12.79	9.91
7	42	12.15	7.99

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