Synthesis of Activated Carbon from Waste Polymer Char via Microwave-Assisted Chemical Treatment

Abstract

Globally, there is an increasing requirement to address environmental problems with sustainable and green solutions. Tyre waste has escalated into a major environmental and health problem due to its disposal in landfills and stockpiling. Recycling them is crucial because of the issues and harm that waste tyres generate. This study aimed to generate activated carbon made from char produced through the pyrolysis of used tyres followed by microwave chemical activation. In this study, pyrolysis of waste tyre was initially carried out under a Nitrogen atmosphere at 600⸰C for 1 hr to produce char. Potassium hydroxide (KOH) was employed on char as the impregnating agent in the chemical activation method. The impregnated char was placed under the microwave oven at variable conditions of microwave power, radiation duration and impregnation ratios. Using a microwave oven, factors like microwave power, microwave radiation duration, and KOH impregnation ratio (IR) were assessed for their effects on produced activated carbon yield and adsorption capabilities. To find the optimum conditions using the microwave, the effect of yield and iodine number was maximum analyzed found to be 29.5% and 902 mg/g respectively at optimum conditions. The optimum parameters were microwave power of 550W, an activation time of 9 minutes, and IR of 1.75. By using response surface methodology (RSM), interactions between microwave power, radiation duration, and IR were taken into account to find the optimum conditions against their responses to iodine number and yield. The optimum conditions by using RSM were microwave power 588 W, activation time 7.2 minutes, and 1.9 IR. The prepared activated carbon was characterized using Scanning Electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and Brunauer-Emmett-Teller (BET) methods. Consequently, mesoporous activated carbon was obtained with microporous volume and surface area up to 0.139 cm3 /g and 599.77 m2 /g. Furthermore, adsorption characteristics were investigated by methylene blue removal from wastewater by studying the effect of pH and conc.