Bitumen and Paraffin Wax Encapsulated Cigarette Butts: Physical Properties and Leachate Analysis

Littered cigarette butts (CBs) are a form of poorly biodegradable waste. Attempts have been made to prevent the pollution caused by the waste through the recycling of CBs in construction materials. A novel method involving the encapsulation of CBs with paraffin wax and bitumen was developed, which investigated its use in hot-dense asphalt concrete with promising results. The objective of this study was to carry out a comprehensive leachate analysis to examine the effectiveness and efficiency of the encapsulation method for the prevention of heavy metal leachates from CBs and to investigate the physical properties of wax and bitumen encapsulated CBs. The leachate analysis was conducted using the Australian Bottle Leaching Procedure (ABLP) for pH values 2.9, 5.0, and 9.2. The leaching behavior of encapsulated CBs was insignificant compared to fresh CBs due to the immobilization of metals after being encapsulated in bitumen and wax. The findings suggest that the variance in pH influences the behavior of the metal concentration leached. Generally, pH 2.9 resulted in the highest metal contamination for all sample types, followed by pH 5.0 and pH 9.2. The water absorption decreased significantly from 383% for fresh CBs to 4% and 5% for bitumen and wax encapsulated CBs. Micro-X-ray CT imaging was used to study and analyze the porosity and pore structure of CBs, and a substantial decrease in porosity from 66% to 0.5% was determined when CBs were encapsulated with bitumen.