Effects of Environmental Factors on the Dynamic Adsorption of n-Hexane by Activated Carbon

n-Hexane, a common low-polarity volatile organic compound (VOC), significantly contributes to atmospheric pollution and poses serious risks to human health. Activated carbon adsorption is the primary industrial method for purifying n-hexane-laden waste gas. However, the performance of industrial adsorption systems varies considerably with changing environmental conditions, and comprehensive quantitative research on this variability is scarce. This study employed bench-scale fixed-bed experiments with single-factor controlled-variable designs to systematically investigate how inlet concentration, bed temperature, and relative humidity influence the dynamic adsorption capacity of activated carbon for n-hexane. The findings indicate a positive correlation between inlet concentration and adsorption capacity, although the marginal gains diminish as concentration increases. Higher temperatures suppress adsorption, with the maximum capacity observed at 15 °C within the tested range (15–55 °C). Considering both performance and industrial cooling costs, an operating temperature range of 15–25 °C is recommended for practical applications. Relative humidity proved to be the most sensitive limiting factor under the tested operating conditions. Water vapor occupies hydrophilic surface sites and induces capillary condensation within micropores, thereby obstructing mass transfer pathways and reducing adsorption efficiency. This study explores the potential microscale mechanisms by which these three critical environmental variables control n-hexane adsorption and proposes targeted strategies for optimizing industrial operating parameters. It provides robust theoretical and experimental support for the efficient industrial treatment of n-hexane-containing waste gas. n-Hexane, a typical low-polarity volatile organic compound (VOC), causes severe atmospheric pollution and poses major hazards to human health. Activated carbon adsorption is the primary industrial purification technology for waste gas containing n-hexane. Industrial adsorption performance fluctuates drastically under changing environmental conditions, yet comprehensive quantitative research on this topic remains limited. This study uses bench-scale fixed-bed experiments with single-factor controlled-variable designs to systematically examine how inlet concentration, bed temperature, and relative humidity affect the dynamic adsorption capacity of activated carbon for n-hexane. The results show that inlet concentration correlates positively with adsorption capacity, though marginal gains gradually decline as concentration rises. Higher temperatures suppress adsorption, with the highest capacity observed at 15 °C among the tested conditions (15–55 °C). Considering both performance and industrial cooling costs, the 15–25 °C range is recommended for practical operation. Relative humidity is the most sensitive limiting factor across the tested operating ranges: water vapor occupies hydrophilic surface sites and triggers capillary condensation inside micropores, clogging mass-transfer pathways and reducing adsorption efficiency. This study discusses the potential microscale mechanisms through which these three key environmental variables control n-hexane adsorption and proposes targeted strategies for optimizing industrial operating parameters. It delivers credible theoretical and experimental backing for high-efficiency industrial treatment of n-hexane-containing waste gas.