Removal of 3,4-dichlorobut-1-ene using ozone oxidation

The efficiency of ozone oxidation in the removal of 3,4-dichlorobut-1-ene (3,4 DCB), a contaminant often present in the aqueous effluents generated by synthetic rubber processes, was studied. Ozone oxidation removed 3,4 DCB completely from the model solutions with initial concentrations ranging from 4 to 64 mg/l over a maximum ozonation time of 7 min. The complete oxidation of 3,4 DCB was mainly due to the direct reaction with ozone molecules at acidic and neutral pH. At alkaline pH ozone oxidation only reduced the 3,4 DCB concentration by 61% over 15 min of ozonation. Methanol used in preparing the 3,4 DCB solutions did not affect the ozone oxidation rate. Ozone oxidation of a 3,4 DCB/methanol solution with an initial 3,4 DCB concentration of 120 mg/l reduced 95% of the 3,4 DCB concentration but only 4% of the Chemical Oxygen Demand (COD) in the solution. The high COD value in the ozonated solution was probably due to the presence of methanol. Ozone degraded 3,4 DCB and chloroprene (CD) in the effluent samples from a synthetic rubber processing plant and resulted in the maximal reduction of the COD by 45%.