Surface modification of carbon-based materials using a double dielectric barrier discharge for efficient removal of OPFRs with different polarity

Abstract

This article utilizes a double dielectric barrier discharge (DBD) technology to enhance the removal of five commonly found highly toxic organophosphorus flame retardants (OPFRs) by modifying carbon-based materials. This study investigated the adsorption performance of carbon-based materials modified under various discharge times, frequencies, and voltage conditions on five different OPFRs. Before the modification, the adsorption amount of TPP was only 0.56 mg/g, but the modification significantly improved the adsorption effect of TPP to 14.8 mg/g. Furthermore, the overall adsorption amount of the flame retardants with five different polarities increased by 70.51 mg/g. The study also examined the adsorption kinetics and isotherms, the dosage effect, and the adsorption mechanism and reusability of the modified carbon materials for OPFRs. In the end, the study found that the optimal adsorption capacity for 5 types of OPFRs was achieved at a voltage frequency of 8 kHz, a voltage of 12 kV, and 15 min. The fitting kinetic and isotherm model determines that chemical adsorption is the main mechanism supplemented by physical adsorption, and Langmuir and Freundlich provide better fitting for the adsorption isotherms. The material exhibits a favorable pore structure, high adsorption capacity, and stable regenerative adsorption performance. The adsorption mechanism for OPFRs involves pore filling, hydrogen bonding, π - π conjugation, and strong electrostatic interaction. The optimal adsorption capacity is 109.81 mg/g. This study provides a new strategy for synthesizing activated carbon materials with broad polarity. The relative standard deviation of all experiments did not exceed 2.88 %.