Preparation and Releasing Characteristics of Controlled Release Potassium Permanganate

Abstract

To extend the duration of KMnO4in the groundwater in situ remediation, controlled release oxidant was prepared by dispersing the KMnO4particles in the molten paraffin wax. Preparation conditions, including KMnO4particles size, ultrasonic treatment time and the weight ratio of KMnO4to wax (P/W) were optimized. The results showed that the average volume particle size of 13.20 μm and ultrasonic treatment of 10 min contribute to the most uniform dispersion of the KMnO4particles in the molten paraffin wax. The scanning electron microscope (SEM) images showed that the increased amount of KMnO4caused the crushed structure of paraffin wax, which resulted in the higher porosity of wax to contain more KMnO4. The KMnO4loading amount increased significantly along with the increase of the P/W. However, the loading amount almost reached saturation by 609.63 mg/g when the P/W increased to 2/1. The releasing characteristics of the samples in the distilled water and the KMnO4residual amount at different radial distance in the sample were examined by the bench scale tests. The releasing of KMnO4could be divided into four periods and stable release took place after 40 d. Controlled release KMnO4oxidant with P/W at 1/35 was used to remove COD in the leachate and 82.9% removal efficiency was obtained after 120 d treatment.