Adsorption of Chlorinated Hydrocarbons by Different Kinds of Soils: Kinetics, Influencing Factors, Mechanism

Abstract

Chlorinated hydrocarbon compounds (CHCs), important components of pesticides and organic solvents, have infiltrated groundwater and aquifers through various pathways. Due to their high toxicity, insolubility, and resistance to degradation, they have posed significant threat to the environment and human health. This study utilized batch static adsorption experiments to investigate the adsorption behavior of typical CHCs on different soil types. By employing adsorption kinetic and isothermal models, as well as grey correlation analysis, the study aimed to determine the relative importance of various influencing factors. Results indicated that clay soil exhibited the highest adsorption capacity for CHCs, with the highest adsorption level of 1,2,4-trichlorobenzen. The results of the study showed that clay soil showed the highest adsorption of 58.86 μg/g of the three CHCs, which was greater than loam soil (52.4 μg/g) and sand soil (46.5 μg/g). The maximum adsorbing capacity of 1,2,4-Trichlorobenzene was reaching to 58.86 μg/g, which was greater than that of p-chlorobenzene (50.1 μg/g) and carbon tetrachloride (40.5 μg/g) in the same soil medium. Furthermore, the study revealed that soil pH influenced the adsorption capacity of CHCs, with neutral pH resulting in the weakest adsorption. The analysis also identified the order of importance of influencing factors for different CHCs. For 1,2,4-trichlorobenzene and chlorobenzene, pollutant concentration was the most influential factor, followed by particle size, zeta potential, pH, and organic matter content. On the other hand, for carbon tetrachloride, pollutant concentration was the most significant factor, followed by particle size, organic matter content, zeta potential, and pH. This study effectively remedied the limitations of the research on soil adsorption of chlorinated hydrocarbons at the present stage, and also provided an important scientific basis for environmental risk assessment and soil pollution prevention and control.

Keywords: Differences in soil properties, Typical chlorinated hydrocarbons, Adsorption characteristics, Impact mechanisms, Order of importance.