Mi Deng

A novel substitute for perfluorooctane sulfonate (PFOS), 6:2 Chlorinated polyfluoroalkyl ether acid (6:2 Cl-PFAES, F-53B), has been widely used in the electroplating and firefighting industries, raising concerns due to increasing environmental prevalence. This study systematically investigated the adsorption characteristics of F-53B by coconut shell activated carbon (CSAC) and elucidated the underlying mechanisms through adsorption kinetics, isotherm modeling, and multi-scale characterization. Results show that the maximum adsorption capacity of CSAC for F-53B reached 261.64 mg/g, with the process best described by the pseudo-second-order kinetic model (R² > 0.97) and the Langmuir isotherm (R² > 0.94). Intraparticle diffusion modeling revealed a three-stage adsorption sequence: surface adsorption (0–2 h), pore diffusion (2–8 h), and dynamic equilibrium (8–48 h). Solution pH influenced adsorption efficiency by regulating surface charge. Under acidic conditions (pH < point of zero charge, pHzpc = 4.49), strong electrostatic interactions between protonated CSAC surfaces and anionic F-53B resulted in an 85% removal efficiency. In contrast, alkaline conditions (pH > 7) led to a 70% reduction in adsorption efficiency (p < 0.05) due to electric repulsion. The microporous-dominated structure of CSAC (specific surface area: 857.69 m²/g; pore volume: 0.34 cm³/g) facilitated synergistic adsorption mechanisms. Oxygen-containing functional groups (C-O, -OH) promoted hydrogen bonding and hydrophobic interactions, enhancing F-53B adsorption. Besides, CSAC is optimized for emergency scenarios, it achieves 99.9% removal efficiency for 1 mg/L F-53B within 8 h at room temperature, with a maximum capacity of 261.64 mg/g; also, it maintains > 85% removal efficiency under wide pH conditions and tolerates coexisting ions (e.g., Cl⁻, SO₄²⁻, Ca²⁺).This study highlights the multi-mechanistic synergy of CSAC in theremoval of F-53B, providing theoretical foundations and technical insights for biochar-based remediation of emerging contaminants.

The outbreak of epidemics such as African swine fever has intensified the use of disinfectants in pig farms, resulting in an increasing residual concentration of disinfectants in environmental media; however, the high-frequency excessive use of disinfectants that damage pig farm manure anaerobic fermentation systems and their mechanisms has not attracted enough attention. Especially, the complex effects of residual disinfectants on anaerobic fermentation systems for pig manure remain poorly understood, thus impeding the application of disinfectants in practical anaerobic fermentation systems. Herein, we explored the effects of glutaraldehyde disinfectant on methane production, effluent physicochemical indices, and microbial communities in a fully automated methanogenic potential test system (AMPTSII). The results show that adding glutaraldehyde led to remarkable alterations in methane production, chemical oxygen demand (COD), volatile solids (VS), and polysaccharide and phosphorus concentrations. During the anaerobic process, the production of methane displayed a notable decrease of 5.0–98% in all glutaraldehyde treatments, and the trend was especially apparent for treatments containing high levels of glutaraldehyde. Comparisons of the effluent quality showed that in the presence of 0.002–0.04% glutaraldehyde, the COD and total phosphorus (TP) increased by 12–310% and 15–27%, respectively. Moreover, the addition of 0.01–0.08% glutaraldehyde decreased the ammonium (NH₄⁺-N) concentration and VS degradation rate by 7.7–15% and 4.9–26.2%. Furthermore, microbiological analysis showed that the glutaraldehyde treatments had adverse effects on the microbial community. Notably, certain functional bacteria were restrained, as highlighted by the decreases in relative abundance and microbial diversity by 1.3–17% and 0.06–21%, respectively. This study provides a theoretical basis for the rational use of disinfectants in anaerobic fermentation systems.