Kinetic Aspect of Chemical Oxygen Demand

Abstract

The purpose of this work is to reveal the kinetic nature of chemical oxygen demand (COD)determined by acidic permanganate method (JIS K0102-1986-17). Integrating rate equation (3)for the consumption of permanganate,
dx/dt=k(b-x)(c-x) (3)
where b and c are the initial concentration of permanganate and an organic compou nd, respectively, x is the concentration of permanganate consumed by the oxidation of the orga nic compound, k is rate constant, and t is reaction time, equation (4) is obtained.
k=1/(b-c)t In nc b(c-x)/c(b-x) (4)
For a given k value, one can calculate the titrant volume (a) of permanganate for various sample volumes (V), using equation (4). The full logarithmic linear relationship (2) holds between the calculated a and V with correlation coefficients above 0.9985.
log α= logh+nlogV (2)
The n values determined by least-squares method are O.74-1.00 (Table 1), which are in good agreement with the experimental values, n = 0.807-0.907.