inorganic chemistry

mechanism, in which a surface-adsorbed molecule reacts with a
molecule coming from the bulk.
Even if the L–H mechanism is defined as the reaction of a sur-
face-adsorbed substrate obeying a Langmuir isotherm governing
the overall rate, the frequently reported experimental evidence,
a reciprocal linear relation between concentration of the sub-
strate in solution and rate of photocatalytic reaction is not
always proof of this mechanism. From the linear plot, two
parameters are calculated( 23 ). One (often shown as“k,”not as
“ks”) is a limiting rate of the reaction at the infinite concentration

0246810

0

5 × 106

1 × 107

1.5× 107

2 × 107

1/r

1/C

kSCkKSr

×= + 1 1 11

0 0.2 0.4 0.6 0.8 1

0

2 × 106

4 × 106

6 × 106

8 × 106

C/r

C

k Sr kKS

C (^1) × C += 1
(b)
(a)
FIG. 7. Simulation of linearized plots for kinetics governed by sur-
face concentration of substrates adsorbed on the photocatalyst surface
in a Langmuirian fashion, wherer,C,k,K, andSare rate of reaction
(mol s^1 ), concentration of a substrate (mol L^1 ), rate constant
(10^4 s^1 ), adsorption equilibrium constant (5 L mol^1 ), and saturated
amount of adsorption (2 10 ^3 mol).
PHOTOCATALYSIS BY INORGANIC SOLID MATERIALS 409