Adsorption Phenomenon of VOCs Released from the Fiber-Reinforced Plastic Production onto Carbonaceous Surface

Abstract

The manufacturing of fiber-reinforced plastics has been linked to the discharge of volatile organic compounds (VOCs), particularly toluene and benzene, which have been identified as posing substantial risks to human health and the environment. To counteract this issue, activated carbons have been suggested as a means of reducing VOC emissions through adsorption. The objective of this study was to investigate the adsorption characteristics of toluene and benzene onto activated carbons produced from coal (AC) and coconut shells (CAC). The study was carried out in an aqueous medium. The findings revealed that the AC sample with higher surface characteristics exhibited a higher adsorption capacity (toluene: 196.0784 mg g−1 and benzene: 181.8182 mg g−1) in comparison to the CAC sample (toluene: 135.1351 mg g−1 and benzene: 116.2791 mg g−1). The superior adsorption performance of AC on both VOCs can be attributed to its higher surface characteristics. The Langmuir model was found to be more appropriate than the Freundlich model, as indicated by the higher coefficient of determination (R2) value of the Langmuir isotherm (avg. R2 = 0.9669) compared to that of the Freundlich isotherm (avg. R2 = 0.9654), suggesting the use of a monolayer adsorption mechanism. The adsorption kinetics of the samples were analyzed using the pseudo-first-order and pseudo-second-order models, and the former was found to be more fitting, indicating that the rate of adsorption is directly proportional to the concentration difference between the solution and the sample surface. The adsorption process was found to be spontaneous and favorable based on the positive value of ΔG_ads. Furthermore, the adsorption process was endothermic and disordered, as indicated by the positive values of ΔH_ads and ΔS_ads. The regeneration efficiency of all the samples was secured more than 95% upon the fifth cycle.